WorldWideScience

Sample records for semicarbazone synthesis electrochemical

  1. Design synthesis and biological evaluation of 2-methylphenyl semicarbazone derivatives

    Directory of Open Access Journals (Sweden)

    Manmohan Singhal

    2011-03-01

    Full Text Available We have used pharmacophore hybridization technique of drug design and designed a pharmacophore model 2-methylphenylsemicarbazone which is having hydrogen acceptor site, hydrogen donor site, lipophilic site etc using ligandscout-2.02 software. A series of 2-methylphenyl-semicarbazone was synthesized and evaluated for their antipyretic activity using boiled cow milk induced pyrexia in rabbits. Compound 11 was the most active compound. The possible metabolites of some selected synthesized chalconesemicarbazones were predicted by computational method using Pallas version-3.1 ADME-Tox prediction software. The major pathway of metabolism was found to be p-hydroxylation and amide hydrolysis.

  2. Synthesis, characterization and biological activities of semicarbazones and their copper complexes.

    Science.gov (United States)

    Venkatachalam, Taracad K; Bernhardt, Paul V; Noble, Chris J; Fletcher, Nicholas; Pierens, Gregory K; Thurecht, Kris J; Reutens, David C

    2016-09-01

    Substituted semicarbazones/thiosemicarbazones and their copper complexes have been prepared and several single crystal structures examined. The copper complexes of these semicarbazone/thiosemicarbazones were prepared and several crystal structures examined. The single crystal X-ray structure of the pyridyl-substituted semicarbazone showed two types of copper complexes, a monomer and a dimer. We also found that the p-nitrophenyl semicarbazone formed a conventional 'magic lantern' acetate-bridged dimer. Electron Paramagnetic Resonance (EPR) of several of the copper complexes was consistent with the results of single crystal X-ray crystallography. The EPR spectra of the p-nitrophenyl semicarbazone copper complex in dimethylsulfoxide (DMSO) showed the presence of two species, confirming the structural information. Since thiosemicarbazones and semicarbazones have been reported to exhibit anticancer activity, we examined the anticancer activity of several of the derivatives reported in the present study and interestingly only the thiosemicarbazone showed activity while the semicarbazones were not active indicating that introduction of sulphur atom alters the biological profile of these thiosemicarbazones. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Synthesis, Characterization and Antimicrobial Evaluation of some Thiazole-Derived Carbamates, Semicarbazones, Amides and Carboxamide

    International Nuclear Information System (INIS)

    Balawi, N.A.A.; ALShaikh, M.A.A.; Alafeefy, A.M.; Khan, K.M.

    2016-01-01

    This study comprises the synthesis and characterization of twenty thiazole-derived carbamates (3a-e), N-substituted amides (8a-h) and carboxamide (10) from 2-aminothiazoles (1a, b) via nucleophilic substitution reactions with activated carbonyl compounds including, chloroformates (2a-d), acid chlorides (7a-e) and glutaric anhydride (9), respectively. Sequential hydrazinolysis of carbamate (3e) and condensation with a variety of aldehydes and ketones (5a d) afforded the corresponding semicarbazones (6a-d). Some selected synthesized compounds were subjected to in vitro antimicrobial evaluation against common pathogens including, Gram+ve bacteria Bacillus subtilis (NRRL B-543) and Staphylococcus aureus, Gram-ve bacteria Escherichia coli (NRRLB-21), yeasts-Candida albicans (NRRLY-477) and Saccharomyces cercvisiae (NRRL Y-567) and fungs Asperigillus niger (NRRL 599). Screening results revealed that most of the tested compounds possess good antimicrobial activity compared to standard drugs. The highest inhibitory effects against Gram-ve Escherichia coli, Gram+ve Staphylococcus aureus, yeast Candida albicans and fungus Aspergillus niger was displayed by amide (8g) bearing the thiophene moiety. (author)

  4. Synthesis, EPR, Electronic and Magnetic Studies on Cobalt (II) Complexes of Semicarbazone and Thiosemicarbazone

    International Nuclear Information System (INIS)

    Chandra, S.; Gupta, L.K.; Sharma, K.K.

    2005-01-01

    Cobalt (II) complexes having the general composition Co(L2) X2 [where Lisopropyl methyl ketone semicarbazone (LLA), isopropyl methyl ketone thiosemicarbazone (LLB), 4-aminoacetophenone semicarbazone (LLC) and4-aminoacetophenone thiosemicarbazone (LLD) and X=Cl] have been synthesized. All the Co(II) complexes reported here have been characterized by elemental analyses, magnetic moments, IR, electronic and EPR spectral studies. All the complexes were found to have magnetic moments corresponding to three unpaired electrons. The possible geometries of the complexes were assigned on the basis of electronic infrared and EPR spectral studies. (author) = = = = = = = = = = = = = = =

  5. Two coordination polymers based on semicarbazone Schiff base and azide: synthesis, crystal structure, electrochemistry, magnetic properties and biological activity

    Czech Academy of Sciences Publication Activity Database

    Shaabani, B.; Khandar, A.A.; Dušek, Michal; Pojarová, Michaela; Mahmoudi, F.; Feher, A.; Kajňaková, M.

    2013-01-01

    Roč. 66, č. 5 (2013), s. 748-762 ISSN 0095-8972 Grant - others:AV ČR(CZ) AP0701 Program:Akademická prémie - Praemium Academiae Institutional support: RVO:68378271 Keywords : Schiff bases * semicarbazone * coordination polymer * structure analyses Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 2.224, year: 2013

  6. Template synthesis of two new supramolecular zinc(II) complexes containing pentadentate N.sub.3./sub.O.sub.2./sub. semicarbazone ligand: Nanostructure synthesis, Hirshfeld surface analysis, and DFT studies

    Czech Academy of Sciences Publication Activity Database

    Tyula, Y.A.; Zabardasti, A.; Goudarziafshar, H.; Roudsari, M.S.; Dušek, Michal; Eigner, Václav

    2017-01-01

    Roč. 1150, Dec (2017), s. 383-394 ISSN 0022-2860 R&D Projects: GA ČR(CZ) GA14-03276S Institutional support: RVO:68378271 Keywords : sonochemical synthesis * Hirshfeld surface analysis * DFT calculations * bis(semicarbazone) * pentagonal-bipyramidal Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 1.753, year: 2016

  7. Synthesis, spectral and thermal studies of some dioxouranium(VI) coordination compounds of 4[N -( 4- hydroxy -3- methoxybenzalidene ) amino] antipyrine semicarbazone and 4[N-(3,4,5- trimethoxybenzalidene) amino] antipyrine semicarbazone

    International Nuclear Information System (INIS)

    Singh, Lakshman; Singh, U.P.; Chakraborti, Indranil

    2001-01-01

    In view of high coordination compounds formed by actinide metal ions, the present work describes the 8, 9 and 10-coordinated compounds of dioxouranium(IV) with 4[N-(4-hydroxy-3-methoxy-benzalidene) amino] antipyrine semicarbazone (HMBAAPS) and 4[N-(3,4,5-trimethoxybenzalidene) amino] antipyrine semicarbazone (TMBAAPS) with the general composition UO 2 X 2 .L (X = Br - , I - , NCS - or ClO 4 ) and UO 2 X 2 .L (X = NO 3 - or CH 3 COO - , and L HMBAAPS or TMBAAPS). All these complexes were characterized through elemental, spectral and thermal studies. (author)

  8. Imidazole incorporated semicarbazone derivatives as a new class of anticonvulsants: design, synthesis and in-vivo screening.

    Science.gov (United States)

    Amir, Mohammad; Ali, Israr; Hassan, Mohd Zaheen

    2013-06-01

    A series of novel imidazole incorporated semicarbazones was synthesized using an appropriate synthetic route and characterized by spectral analysis (IR, 1H NMR, 13C NMR and Mass). The anticonvulsant activity of the synthesized compounds was determined using doses of 30, 100, and 300 mg kg-1 against maximal electroshock seizure (MES), subcutaneous pentylenetetrazole (scPTZ) induced seizure and minimal neurotoxicity test. Six compounds exhibited protection in both models and 2-(1-(4-chlorophenyl)-2-(1H-imidazol-1-yl)ethylidene)-N-p-tolylsemicarbazone emerged as the most active compound of the series without any neurotoxicity and significant CNS depressant effect. Liver enzyme estimations (SGOT, SGPT, Alkaline phosphatase) of the compound also showed no significant change in the enzymes levels. Moreover, it caused 80% elevation of γ-amino butyric acid (GABA) levels in the whole mice brain, thus indicating that it could be a promising candidate in designing of a potent anticonvulsant drug.

  9. Ni(II, Pd(II and Pt(II complexes with ligand containing thiosemicarbazone and semicarbazone moiety: synthesis, characterization and biological investigation

    Directory of Open Access Journals (Sweden)

    SULEKH CHANDRA

    2008-07-01

    Full Text Available The synthesis of nickel(II, palladium(II and platinum(II complexes with thiosemicarbazone and semicarbazone of p-tolualdehyde are reported. All the new compounds were characterized by elemental analysis, molar conductance measurements, magnetic susceptibility measurements, mass, 1H-NMR, IR and electronic spectral studies. Based on the molar conductance measurements in DMSO, the complexes may be formulated as [Ni(L2Cl2] and [M(L2]Cl2 (where M = Pd(II and Pt(II due to their non-electrolytic and 1:2 electrolytic nature, respectively. The spectral data are consistent with an octahedral geometry around Ni(II and a square planar geometry for Pd(II and Pt(II, in which the ligands act as bidentate chelating agents, coordinated through the nitrogen and sulphur/oxygen atoms. The ligands and their metal complexes were screened in vitro against fungal species Alternaria alternata, Aspergillus niger and Fusarium odum, using the food poison technique.

  10. (E-1-Phenylethanone semicarbazone

    Directory of Open Access Journals (Sweden)

    Hoong-Kun Fun

    2009-08-01

    Full Text Available In the title compound, C9H11N3O, the benzene ring is disordered over two positions with refined occupancies of 0.922 (5 and 0.078 (5. The program PLATON [Spek (2009. Acta Cryst. D65, 148–155] recommends the solution in the space group C2/m with a = 7.3050 (3, b = 6.6745 (2, c = 18.3853 (6 Å and β = 96.986 (2°. However, the large number of non-extinct reflections needed to be ignored if C2/m is chosen suggested that the space group is incorrect, even though the R values are lower than that for P21/c. The semicarbazone group is essentially planar, with a maximum deviation of 0.046 (1 Å for one of the N atoms. The mean plane of the semicarbazone group forms dihedral angles of 33.61 (8 and 39.1 (9° with the benzene ring of the major and minor components, respectively. In the crystal structure, molecules are linked by intermolecular N—H...O hydrogen bonds into extended chains along the c axis. The crystal structure is further stabilized by weak intermolucular C—H...π interactions.

  11. Synthesis and In Vitro and In Vivo Evaluation of a New 68Ga-Semicarbazone Complex: Potential PET Radiopharmaceutical for Tumor Imaging

    Directory of Open Access Journals (Sweden)

    N. S. Al-Hokbany

    2014-01-01

    Full Text Available In an attempt to develop new tumor imaging radiotracers with favorable biochemical properties, we have synthesized new 68Ga-2-acetylpyridine semicarbazone (68Ga-[APSC]2 as a potential positron emission tomography (PET tumor imaging agent using a straightforward and a one-step simple reaction. Radiochemical yield and purity were quantitative without HPLC purification. Biodistribution studies in nude mice model bearing human MDA-MB-231 cell line xenografts displayed significant tumor uptake of 68Ga-[APSC]2 radiotracer after 2 h postinjection (p.i.. The initial results demonstrate that 68Ga-[APSC]2 radiotracer may be useful probe for detecting and staging of hypoxic tumor using PET imaging modality.

  12. Direct electrochemical synthesis of metal alcoholates

    International Nuclear Information System (INIS)

    Shrejder, V.A.; Turevskaya, E.P.; Kozlova, N.I.; Turova, N.Ya.

    1981-01-01

    Conditions of electrochemical synthesis of Ga, Sc, Y, Ge, Ti, Zr, Nb and Ta alcoholates during anodic metal dissolution in absolute alcohols in the presence of background electrolyte are studied. R 4 NBr and R 4 NBF 4 salts are optimum background electrolytes. Application limits of this synthetical method using different metals as anode are determined. It is supposed that alkoxyhalogenides the nature of which determines further direction of electrode process, are the primary products of anodic oxidation of metals [ru

  13. Carbon Onions: Synthesis and Electrochemical Applications

    Energy Technology Data Exchange (ETDEWEB)

    McDonough, John K. [Drexel Univ., Philadelphia, PA (United States). Dept. of Materials Science and Engineering; Gogotsi, Y. [Drexel Univ., Philadelphia, PA (United States). Dept. of Materials Science and Engineering

    2013-01-01

    Onion-like carbon structures have been synthesized in many ways and large scale production is currently under study. The annealing method can satisfy the need for large scale production, though the ideal spherical shape is unachievable, and the temperature attainable in this method is not sufficient for treating the entire particle. The arc-discharge method provides an alternate pathway toward large scale synthesis. Due to its structure and electrochemical properties, carbon onions can be used as materials for electrochemical double layer capacitors (EDLC) and can be used to store energy across a much wider temperature range, which gives these materials advantages over conventional EDLCs. This and other aspects of carbon onions are discussed in this article.

  14. Spectroscopic studies on Isatin-3-Semicarbazone and Isatin-3 ...

    African Journals Online (AJOL)

    ... bombardment (FAB) and negative ion chemical ionization (NICI) mass spectra are also reported. Fragmentation of molecular and pseudomolecular ions are tabulated and rationalized. KEY WORDS: IH NMR, 13C NMR, Semicarbazone thiosemicarbazone, mass spectra, negative ion chemical ionization, fragmentation.

  15. Synthesis of magnetite nanoparticles using electrochemical oxidation

    Directory of Open Access Journals (Sweden)

    Ye. Ya. Levitin

    2014-08-01

    Full Text Available The monodisperse magnetite nanoparticles are promising for use in the biomedical industry for targeted drug delivery, cell separation and biochemical products, Magnetic Resonance Imaging, immunological studies, etc. Classic method for the synthesis of magnetite is the chemical condensation Elmore’s, it is simple and cheap, but it is complicated by the formation of side compounds which impair the magnetic properties of the final product. Biological and medical purposes require high purity magnetite nanoparticles. Electrochemical methods of producing nanoparticles of magnetite acquire significant spread. The kinetics of electrochemical processes are a function of a larger number of parameters than the kinetics of conventional chemical reaction, thus electrochemical reactions can be thinner and more completely adjusted to give a predetermined size nanoparticles. In the kinetics of the electrochemical oxidation and reduction the important role is played by the nature of the electrode. In many industrial processes, it is advisable to use lead dioxide anodes with titanium current lead. Purpose of the work To determine the optimum conditions of electrochemical oxidation of Fe2+ Fe3+to produce magnetite with high purity and improved magnetic characteristics. Materials and methods Electrochemical studies were carried out in a glass cell ЯСЭ-2 using a potentiostat ПИ-50-1.1 and a recording device ПДА1. Reference electrode - silver chloride ЭВЛ1М 3.1, potentials listed on the hydrogen scale. The test solution contained 80 g/ l FeSO4×7H2O and H2SO4(to pH 1. The pH of the solution was measured with a pH–meter « рН–150». Concentration ratio of Fe3+/Fe2+in the solution was measured by permanganometric method. Magnetite particle sizes were measured by an electron microscope computer ЭВМ-100Л, an increasing is 2×105. Saturation magnetization was evaluated by the magnetization curve, for the measured sample in the field with strength

  16. Electrochemically Active Biofilms Assisted Nanomaterial Synthesis for Environmental Applications

    KAUST Repository

    Ahmed, Elaf

    2017-01-01

    Nanomaterials have a great potential for environmental applications due to their high surface areas and high reactivity. This dissertation investigated the use of electrochemically active biofilms (EABs) as a synthesis approach for the fabrication

  17. Research progress in the electrochemical synthesis of ferrate(VI)

    International Nuclear Information System (INIS)

    Macova, Zuzana; Bouzek, Karel; Hives, Jan; Sharma, Virender K.; Terryn, Raymond J.; Baum, J. Clayton

    2009-01-01

    There is renewed interest in the +6 oxidation state of iron, ferrate (VI) (Fe VI O 4 2- ), because of its potential as a benign oxidant for organic synthesis, as a chemical in developing cleaner ('greener') technology for remediation processes, and as an alternative for environment-friendly battery cathodes. This interest has led many researchers to focus their attention on the synthesis of ferrate(VI). Of the three synthesis methods, electrochemical, wet chemical and thermal, electrochemical synthesis has received the most attention due to its ease and the high purity of the product. Moreover, electrochemical processes use an electron as a so-called clean chemical, thus avoiding the use of any harmful chemicals to oxidize iron to the +6 oxidation state. This paper reviews the development of electrochemical methods to synthesize ferrate(VI). The approaches chosen by different laboratories to overcome some of the difficulties associated with the electrochemical synthesis of ferrate(VI) are summarized. Special attention is paid to parameters such as temperature, anolyte, and anode material composition. Spectroscopic work to understand the mechanism of ferrate(VI) synthesis is included. Recent advances in two new approaches, the use of an inert electrode and molten hydroxide salts, in the synthesis of ferrate(VI) are also reviewed. Progress made in the commercialization of ferrate(VI) continuous production is briefly discussed as well

  18. Controlled synthesis and electrochemical properties of vanadium ...

    Indian Academy of Sciences (India)

    Vanadium oxides (V3O7·H2O and VO2) with different morphologies have been selectively synthesized ... appeared at around 68 ◦C. Furthermore, the electrochemical properties of V3O7·H2O nanobelts, VO2(B) .... morphologies of shape-controlled orthorhombic V3O7·H2O ..... condition, as shown in figures S14i and j.

  19. Progress in electrochemical synthesis of magnetic iron oxide nanoparticles

    International Nuclear Information System (INIS)

    Ramimoghadam, Donya; Bagheri, Samira; Hamid, Sharifah Bee Abd

    2014-01-01

    Recently, magnetic iron oxide particles have been emerged as significant nanomaterials due to its extensive range of application in various fields. In this regard, synthesis of iron oxide nanoparticles with desirable properties and high potential applications are greatly demanded. Therefore, investigation on different iron oxide phases and their magnetic properties along with various commonly used synthetic techniques are remarked and thoroughly described in this review. Electrochemical synthesis as a newfound method with unique advantages is elaborated, followed by design approaches and key parameters to control the properties of the iron oxide nanoparticles. Additionally, since the dispersion of iron oxide nanoparticles is as important as its preparation, surface modification issue has been a serious challenge which is comprehensively discussed using different surfactants. Despite the advantages of the electrochemical synthesis method, this technique has been poorly studied and requires deep investigations on effectual parameters such as current density, pH, electrolyte concentration etc. - Highlights: • IONPs are applied in chemical industries, medicine, magnetic storage etc. • Electrochemical synthesis (EC) is convenient, eco-friendly, selective and low-cost. • EC key factors are current density, pH, electrolyte concentration, electrode type. • Organic, inorganic and biological materials can be used to modify IONPs’ surface. • The physicochemical properties of IONPs can be controlled by adding surfactants

  20. Synthesis and characterization of poly aniline for electrochemical biosensor construction

    International Nuclear Information System (INIS)

    Magalhaes, Gleice S.L.; Southgate, Erica F.; Alhadeff, Eliana M.; Guimaraes, Maria Jose O.C.

    2011-01-01

    Conductors polymers have many attractive interests to the industry due their highly technological applications. This work treats specially of polyaniline because it's large electrical conductivity, electrochemical properties, associate to the chemical stability in environmental conditions and synthesis facility. The main of this work is the application in a construction of an electrochemical biosensor for ethanol detection and quantification. Different conditions of synthesis of the conductor emeraldine polyaniline form were studied, investigated the influence of the dopant agent and the reactional environment conditions temperature on the reaction yield and conductivities. The polyaniline that showed the best conductivity were characterized by differential and thermal gravimetric analysis, infrared spectroscopy, X ray diffraction, and cycle voltammetry, comparing with the commercial polyaniline. (author)

  1. Electrochemical Synthesis of Ammonia in Solid Electrolyte Cells

    International Nuclear Information System (INIS)

    Garagounis, Ioannis; Kyriakou, Vasileios; Skodra, Aglaia; Vasileiou, Eirini; Stoukides, Michael

    2014-01-01

    Developed in the early 1900s, the “Haber–Bosch” synthesis is the dominant NH 3 synthesis process. Parallel to catalyst optimization, current research efforts are also focused on the investigation of new methods for ammonia synthesis, including the electrochemical synthesis with the use of solid electrolyte cells. Since the first report on Solid State Ammonia Synthesis (SSAS), more than 30 solid electrolyte materials were tested and at least 15 catalysts were used as working electrodes. Thus far, the highest rate of ammonia formation reported is 1.13 × 10 -8 mol s -1 cm -2 , obtained at 80°C with a Nafion solid electrolyte and a mixed oxide, SmFe 0.7 Cu 0.1 Ni 0.2 O 3 , cathode. At high temperatures (>500°C), the maximum rate was 9.5 × 10 −9 mol s -1 cm -2 using Ce 0.8 Y 0.2 O 2-δ –[Ca 3 (PO 4 ) 2 –K 3 PO 4 ] as electrolyte and Ag–Pd as cathode. In this paper, the advantages and the disadvantages of SSAS vs. the conventional process and the requirements that must be met in order to promote the electrochemical process into an industrial level are discussed.

  2. Electrochemical Synthesis of Ammonia in Solid Electrolyte Cells

    Energy Technology Data Exchange (ETDEWEB)

    Garagounis, Ioannis; Kyriakou, Vasileios [Department of Chemical Engineering, Aristotle University of Thessaloniki, Thessaloniki (Greece); Chemical Processes and Energy Resources Institute, Center for Research and Technology Hellas, Thessaloniki (Greece); Skodra, Aglaia [Chemical Processes and Energy Resources Institute, Center for Research and Technology Hellas, Thessaloniki (Greece); Vasileiou, Eirini; Stoukides, Michael, E-mail: stoukidi@cperi.certh.gr [Department of Chemical Engineering, Aristotle University of Thessaloniki, Thessaloniki (Greece); Chemical Processes and Energy Resources Institute, Center for Research and Technology Hellas, Thessaloniki (Greece)

    2014-01-17

    Developed in the early 1900s, the “Haber–Bosch” synthesis is the dominant NH{sub 3} synthesis process. Parallel to catalyst optimization, current research efforts are also focused on the investigation of new methods for ammonia synthesis, including the electrochemical synthesis with the use of solid electrolyte cells. Since the first report on Solid State Ammonia Synthesis (SSAS), more than 30 solid electrolyte materials were tested and at least 15 catalysts were used as working electrodes. Thus far, the highest rate of ammonia formation reported is 1.13 × 10{sup -8} mol s{sup -1} cm{sup -2}, obtained at 80°C with a Nafion solid electrolyte and a mixed oxide, SmFe{sub 0.7}Cu{sub 0.1}Ni{sub 0.2}O{sub 3}, cathode. At high temperatures (>500°C), the maximum rate was 9.5 × 10{sup −9} mol s{sup -1} cm{sup -2} using Ce{sub 0.8}Y{sub 0.2}O{sub 2-δ}–[Ca{sub 3}(PO{sub 4}){sub 2}–K{sub 3}PO{sub 4}] as electrolyte and Ag–Pd as cathode. In this paper, the advantages and the disadvantages of SSAS vs. the conventional process and the requirements that must be met in order to promote the electrochemical process into an industrial level are discussed.

  3. Electrochemical Synthesis of Ammonia in Solid Electrolyte Cells

    Directory of Open Access Journals (Sweden)

    Ioannis eGaragounis

    2014-01-01

    Full Text Available Developed in the early 1900's, the Haber-Bosch synthesis is the dominant NH3 synthesis process. Parallel to catalyst optimization, current research efforts are also focused on the investigation of new methods for ammonia synthesis, including the electrochemical synthesis with the use of solid electrolyte cells. Since the first report on Solid State Ammonia Synthesis (SSAS, more than 30 solid electrolyte materials were tested and at least 15 catalysts were used as working electrodes. Thus far, the highest rate of ammonia formation reported is 1.13×10−8 mol s−1 cm−2, obtained at 80°C with a Nafion solid electrolyte and a mixed oxide, SmFe0.7Cu0.1Ni0.2O3, cathode. At high temperatures (>500oC the maximum rate was 9.5*10-9 mol s−1 cm−2 using Ce0.8Y0.2O2-δ -[Ca3(PO42 -K3PO4] as electrolyte and Ag-Pd as cathode. In this paper, the advantages and the disadvantages of SSAS vs the conventional process and the requirements that must be met in order to promote the electrochemical process into an industrial level, are discussed.

  4. Electrochemical synthesis of highly crystalline copper nanowires

    International Nuclear Information System (INIS)

    Kaur, Amandeep; Gupta, Tanish; Kumar, Akshay; Kumar, Sanjeev; Singh, Karamjeet; Thakur, Anup

    2015-01-01

    Copper nanowires were fabricated within the pores of anodic alumina template (AAT) by template synthesis method at pH = 2.9. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to investigate the structure, morphology and composition of fabricated nanowires. These characterizations revealed that the deposited copper nanowires were highly crystalline in nature, dense and uniform. The crystalline copper nanowires are promising in application of future nanoelectronic devices and circuits

  5. A new inorganic-organic nanohybrid based on a copper(II) semicarbazone complex and the PMo.sub.12./sub.O.sup.3-./sup..sub.40./sub. polyanion: synthesis, characterization, crystal structure and photocatalytic activity for degradation of cationic dyes

    Czech Academy of Sciences Publication Activity Database

    Farhadi, S.; Mahmoudi, F.; Dušek, Michal; Eigner, Václav; Kučeráková, Monika

    2017-01-01

    Roč. 122, Jan (2017), s. 247-256 ISSN 0277-5387 R&D Projects: GA ČR(CZ) GA14-03276S; GA MŠk LO1603 EU Projects: European Commission(XE) CZ.2.16/3.1.00/24510 Institutional support: RVO:68378271 Keywords : inorganic-organic hybrid * semicarbazone complex * nanohybrid * photodegradation * cationic dyes Subject RIV: CA - Inorganic Chemistry OBOR OECD: Inorganic and nuclear chemistry Impact factor: 1.926, year: 2016

  6. Zr (IV COMPLEXES OF SOME NITROGEN-OXYGEN DONOR LIGANDS (SEMICARBAZONES & SALICYLALDAZINE

    Directory of Open Access Journals (Sweden)

    Z F DAWOOD

    2002-06-01

    Full Text Available Complexes containing mixed ligands of zirconium (IV have been synthesized by the reaction of zirconium (IV nitrate (Zr(NO34, 5H2O with salicylaldazine (SAH2 and semicarbazone ligands benzaldehyde semicarbazone (BSCH, 4-methoxybenzaldehyde semicarbzone (MBSCH, 2-chlorobenzaldehyde semicrbazone (CISCH and cinnamaldehyde semicarbazone (CinSCH forming complexes of the type [Zr2(SAH2(SCH2](NO38 and [Zr2(SA2 (SC2](NO32 in neutral and basic medium respectively. The ligands and their complexes are characterized physico-chemically.

  7. Electrochemical synthesis and characterization of copper (I oxide

    Directory of Open Access Journals (Sweden)

    Bugarinović Sanja J.

    2009-01-01

    Full Text Available The quest and need for clean and economical energy sources have increased interest in the development of thin film cells technologies. Electrochemical deposition is an attractive method for synthesis of thin films. It offers the advantages of low synthesis temperature, low cost and high purity. Copper (I oxide or cuprous oxide is an oxide semiconductor which is used as the anodic material in the form of thin film in lithium batteries and solar cells. The cathodic process of synthesis of cuprous oxide thin film is carried out in a potentiostatic mode from the organic electrolyte. The process parameters are chosen in that way to accomplish maximum difference between the potentials at which Cu2O and CuO are obtained. The electrochemical characterization was carried out by cyclic voltammetry. The electrodeposition techniques are particularly well suited for the deposition of single elements but it is also possible to carry out simultaneous depositions of several elements and syntheses of well-defined alternating layers of metals and oxides with thicknesses down to a few nm. Nanomaterials exhibit novel physical properties and play an important role in fundamental research. In addition, cuprous oxide is commonly used as a pigment, a fungicide, and an antifouling agent for marine paints. It is insoluble in water and organic solvents. This work presents the examinations of the influence of bath, temperature, pH and current density on the characteristics of electrochemically synthesized cuprous oxide. In the 'classic' process of synthesis, which is carried out under galvanostatic conditions on the anode, the grain size of the powder decreases with the increase in current density while the grain colour becomes lighter. The best commercial quality of the Cu2O (grain size, colour, content of choride was obtained at the temperature of 80°C, concentration of NaCl of 3 mol/dm3 and current density of 400 A/m2.

  8. Nickel-cobalt hydroxide nanosheets: Synthesis, morphology and electrochemical properties.

    Science.gov (United States)

    Schneiderová, Barbora; Demel, Jan; Zhigunov, Alexander; Bohuslav, Jan; Tarábková, Hana; Janda, Pavel; Lang, Kamil

    2017-08-01

    This paper reports the synthesis, characterization, and electrochemical performance of nickel-cobalt hydroxide nanosheets. The hydroxide nanosheets of approximately 0.7nm thickness were prepared by delamination of layered nickel-cobalt hydroxide lactate in water and formed transparent colloids that were stable for months. The nanosheets were deposited on highly oriented pyrolytic graphite by spin coating, and their electrochemical behavior was investigated by cyclic voltammetry in potassium hydroxide electrolyte. Our method of electrode preparation allows for studying the electrochemistry of nanosheets where the majority of the active centers can participate in the charge transfer reaction. The observed electrochemical response was ascribed to mutual compensation of the cobalt and nickel response via electron sharing between these metals in the hydroxide nanosheets, a process that differentiates the behavior of nickel-cobalt hydroxide nanosheets from single nickel hydroxide or cobalt hydroxide nanosheets or their physical mixture. The presence of cobalt in the nickel-cobalt hydroxide nanosheets apparently decreases the time of electrochemical activation of the nanosheet layer, which for the nickel hydroxide nanosheets alone requires more potential sweeps. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Synthesis, Characterization, and Electrochemical Properties of Polyaniline Thin Films

    Science.gov (United States)

    Rami, Soukaina

    Conjugated polymers have been used in various applications (battery, supercapacitor, electromagnetic shielding, chemical sensor, biosensor, nanocomposite, light-emitting-diode, electrochromic display etc.) due to their excellent conductivity, electrochemical and optical properties, and low cost. Polyaniline has attracted the researchers from all disciplines of science, engineering, and industry due to its redox properties, environmental stability, conductivity, and optical properties. Moreover, it is a polymer with fast electroactive switching and reversible properties displayed at low potential, which is an important feature in many applications. The thin oriented polyaniline films have been fabricated using self-assembly, Langmuir-Blodgett, in-situ self-assembly, layer-by-layer, and electrochemical technique. The focus of this thesis is to synthesize and characterize polyaniline thin films with and without dyes. Also, the purpose of this thesis is to find the fastest electroactive switching PANI electrode in different electrolytic medium by studying their electrochemical properties. These films were fabricated using two deposition techniques: in-situ self-assembly and electrochemical deposition. The characterization of these films was done using techniques such as Fourier Transform Infrared Spectroscopy (FTIR), UV-spectroscopy, Scanning Electron Microscope (SEM), and X-Ray Diffraction (XRD). FTIR and UV-spectroscopy showed similar results in the structure of the polyaniline films. However, for the dye incorporated films, since there was an addition in the synthesis of the material, peak locations shifted, and new peaks corresponding to these materials appeared. The 1 layer PANI showed compact film morphology, comparing to other PANI films, which displayed a fiber-like structure. Finally, the electrochemical properties of these thin films were studied using cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) in

  10. Electrochemical synthesis of nanosized hydroxyapatite by pulsed direct current method

    Energy Technology Data Exchange (ETDEWEB)

    Nur, Adrian; Rahmawati, Alifah; Ilmi, Noor Izzati; Affandi, Samsudin; Widjaja, Arief [Departement of Chemical Engineering, Faculty of Industrial Technology, Sepuluh Nopember Institute of Technology, Kampus ITS Sukolilo, Surabaya 60111 (Indonesia)

    2014-02-24

    Synthesis of nanosized of hydroxyapatite (HA) by electrochemical pulsed direct current (PDC) method has been studied. The aim of this work is to study the influence of various PDC parameters (pH initial, electrode distance, duty cycle, frequency, and amplitude) on particle surface area of HA powders. The electrochemical synthesis was prepared in solution Ca{sup 2+}/EDTA{sup 4−}/PO{sub 4}{sup 3+} at concentration 0.25/0.25/0.15 M for 24 h. The electrochemical cell was consisted of two carbon rectangular electrodes connected to a function generator to produce PDC. There were two treatments for particles after electrosynthesized, namely without aging and aged for 2 days at 40 °C. For both cases, the particles were filtered and washed by demineralized water to eliminate the impurities and unreacted reactants. Then, the particles were dried at 100 °C for 2 days. The dried particles were characterized by X-ray diffraction, surface area analyzer, scanning electron microscopy (SEM), Fourier transform infrared spectra and thermogravimetric and differential thermal analysis. HA particles can be produced when the initial pH > 6. The aging process has significant effect on the produced HA particles. SEM images of HA particles showed that the powders consisted of agglomerates composed of fine crystallites and have morphology plate-like and sphere. The surface area of HA particles is in the range of 25 – 91 m{sup 2}/g. The largest particle surface area of HA was produced at 4 cm electrode distance, 80% cycle duty, frequency 0.1 Hz, amplitude 9 V and with aging process.

  11. Electrochemically Active Biofilms Assisted Nanomaterial Synthesis for Environmental Applications

    KAUST Repository

    Ahmed, Elaf

    2017-12-01

    Nanomaterials have a great potential for environmental applications due to their high surface areas and high reactivity. This dissertation investigated the use of electrochemically active biofilms (EABs) as a synthesis approach for the fabrication and environmental applications of different nanomaterials. Bacteria in EABs generate electrons upon consuming electron donor and have the ability to transport these electrons to solid or insoluble substrates through extracellular electron transport (EET) mechanism. The extracellularly transported electrons, once utilized, can lead to nanoparticle synthesis. In this dissertation, noble metal (i.e., Au, Pd, and Pt) ultra-small nanoparticles (USNPs) were first synthesized with the assistance by the EABs. The assynthesized USNPs had a size range between 2 and 7 nm and exhibited excellent catalytic performance in dye decomposition. Also in this research, a two-dimensional (2D) cobalt nanosheet was successfully synthesized in the presence of EABs. A simple biogenic route led to the transformation of cobalt acetate to produce a green, toxic free homogeneous 2D cobalt nanosheet structure. Further, TiO2 nanotubes were successfully combined with the noble metal USNPs to enhance their photocatalytic activity. In this work, for the first time, the noble metal USNPs were directly reduced and decorated on the internal surfaces of the TiO2 nanotubes structure assisted by the EABs. The USNPs modified TiO2 nanotubes generated significantly improved photoelectrocatatlyic performances. This dissertation shines lights on the use of EABs in ultra-small nanoparticle synthesis.

  12. Alternating voltage-induced electrochemical synthesis of colloidal Au nanoicosahedra

    Energy Technology Data Exchange (ETDEWEB)

    McCann, Kevin; Cloud, Jacqueline E.; Yang, Yongan, E-mail: yonyang@mines.edu [Colorado School of Mines, Department of Chemistry and Geochemistry (United States)

    2013-11-15

    A simple method of alternating voltage-induced electrochemical synthesis has been developed to synthesize highly dispersed colloidal Au nanoicosahedra of 14 ± 3 nm in size. This simple and effective method uses a common transformer to apply a zero-offset alternating voltage to a pair of identical Au electrodes that are immersed in an electrolyte solution containing ligands. The obtained Au nanoicosahedra in this work are among the smallest Au icosahedra synthesized in aqueous solutions. A series of experimental conditions have been studied, such as voltage, the electrolyte identity and concentration, stabilizer identity and concentration, and reaction temperature. The mechanistic study indicates that Au nanoicosahedra are produced on electrode surfaces through an intermediate state of AuO{sub x}. The kinetic rate constant of these Au icosahedra in catalyzing the reduction of 4-nitrophenol with sodium borohydride is found much larger than the literature values of similar Au nanocrystals. In addition, the synthesis of Au–Pd-alloyed NCs has also been attempted.Graphical Abstract.

  13. Electrochemical Synthesis of a Microporous Conductive Polymer Based on a Metal-Organic Framework Thin Film

    KAUST Repository

    Lu, Chunjing; Ben, Teng; Xu, Shixian; Qiu, Shilun

    2014-01-01

    A new approach to preparing 3D microporous conductive polymer has been demonstrated in the electrochemical synthesis of a porous polyaniline network with the utilization of a MOF thin film supported on a conducting substrate. The prepared porous

  14. Characterization and optimization of cathodic conditions for H2O2 synthesis in microbial electrochemical cells

    Science.gov (United States)

    Cathode potential and O2 supply methods were investigated to improve H2O2 synthesis in an electrochemical cell, and optimal cathode conditions were applied for microbial electrochemical cells (MECs). Using aqueous O2 for the cathode significantly improved current density, but H2...

  15. Electrochemical synthesis of magnetic nanostructures using anodic aluminum oxide templates

    Science.gov (United States)

    Gong, Jie

    In this dissertation, template electrodeposition was employed to fabricate high quality magnetic nanostructures suited for the reliable investigation of novel spintronics phenomena such as CIMS, BMR, and CPP-GMR. Several critical aspects/steps relating to the synthesis process were investigated in this work. In order to obtain high quality magnetic nanostructures, free-standing and Si-supported anodic aluminum oxide templates with closely controlled pore diameters, lengths, as well as constriction sizes, were synthesized by anodization, followed by appropriate post-processing. The pore opening size on the barrier layer can be controlled down to 5 nm by ion beam etching. After optimization of the compositional, structural, and magnetic properties of homogeneous FeCoNiCu layers electrodeposited under different conditions, the pulsed deposition process of FeCoNI/Cu multilayers on n-Si was studied. The influence of Cu deposition potential and Fe2+ concentration on microstructure, chemical and electrochemical properties, magnetic properties, and hence magnetotransport properties were assessed. The dissolution of the FM layer during potential transition was minimized in order to control interface sharpness. Combined with the systematic sublayer thickness and FM layer composition optimization, unprecedented GMR sensitivity of 0.11%/Oe at 5-15 Oe was obtained. Growth of multilayer nanowires was performed, and contact to a single wire was attempted using an electrochemical technique. We succeeded in addressing a small number of nanowires and measured a CPP-GMR of 17%. Template electrodeposition thus provides a promising way to repeatably fabricate prototypes for spin dependent transport studies.

  16. Conversion of Carbon Dioxide to Ethanol by Electrochemical Synthesis Method Using Brass as A Cathode

    Directory of Open Access Journals (Sweden)

    Septian Ramadan

    2017-09-01

    Full Text Available The effect of potential and gas flow rate were investigated to determine the optimum conditions of the electrochemical synthesis process to convert carbon dioxide to ethanol. The conversion process is carried out using a NaHCO3 electrolyte solution in an electrochemical reactor equipped with a cathode and anode. As cathode is used brass, while as anode is used carbon. The result of the electrochemical synthesis process was analyzed by gas chromatography to determine the content of the compounds produced qualitatively and quantitatively. The optimum electrochemical synthesis conditions to convert carbon dioxide to ethanol are potential and gas flow rate are 3 volts and 0.5 L/minutes with ethanol concentration yielded 1.32%.

  17. The antimicrobial activity of lapachol and its thiosemicarbazone and semicarbazone derivatives

    Directory of Open Access Journals (Sweden)

    Marina Azevedo Souza

    2013-05-01

    Full Text Available Lapachol was chemically modified to obtain its thiosemicarbazone and semicarbazone derivatives. These compounds were tested for antimicrobial activity against several bacteria and fungi by the broth microdilution method. The thiosemicarbazone and semicarbazone derivatives of lapachol exhibited antimicrobial activity against the bacteria Enterococcus faecalis and Staphylococcus aureus with minimal inhibitory concentrations (MICs of 0.05 and 0.10 µmol/mL, respectively. The thiosemicarbazone and semicarbazone derivatives were also active against the pathogenic yeast Cryptococcus gattii (MICs of 0.10 and 0.20 µmol/mL, respectively. In addition, the lapachol thiosemicarbazone derivative was active against 11 clinical isolates of Paracoccidioides brasiliensis, with MICs ranging from 0.01-0.10 µmol/mL. The lapachol-derived thiosemicarbazone was not cytotoxic to normal cells at the concentrations that were active against fungi and bacteria. We synthesised, for the first time, thiosemicarbazone and semicarbazone derivatives of lapachol. The MICs for the lapachol-derived thiosemicarbazone against S. aureus, E. faecalis, C. gattii and several isolates of P. brasiliensis indicated that this compound has the potential to be developed into novel drugs to treat infections caused these microbes.

  18. Electrochemical oxidation of 4-morpholinoaniline in aqueous solutions: Synthesis of a new trimer of 4-morpholinoaniline

    International Nuclear Information System (INIS)

    Esmaili, Roya; Nematollahi, Davood

    2011-01-01

    Research highlights: → Electrochemical study of 4-morpholinoaniline in various pHs. → Electrochemical trimerization of 4-morpholinoaniline in aqueous solution. → Green method for the synthesis of '4-morpholinoaniline-trimer'. → Potential-pH diagram for 4-morpholinoaniline. - Abstract: Electrochemical oxidation of 4-morpholinoaniline has been studied in various pHs using cyclic voltammetry and controlled-potential coulometry. The electrochemical trimerization of 4-morpholinoaniline is described and its mechanism has been studied in aqueous solution. This method provides a green, reagent-less, and environmentally friendly procedure with high atom economy, for the synthesis of '4-morpholinoaniline-trimer' using a carbon electrode in an undivided cell in good yield and purity.

  19. Conversion of Carbon Dioxide into Ethanol by Electrochemical Synthesis Method Using Cu-Zn Electrode

    Science.gov (United States)

    Riyanto; Ramadan, S.; Fariduddin, S.; Aminudin, A. R.; Hayatri, A. K.

    2018-01-01

    Research on conversion of carbon dioxide into ethanol has been done. The conversion process is carried out in a sodium bicarbonate electrolyte solution in an electrochemical synthesis reactor. As cathode was used Cu-Zn, while as anode carbon was utilized. Variations of voltage, concentration of sodium bicarbonate electrolyte solution and time of electrolysis were performed to determine the optimum conditions to convert carbon dioxide into ethanol. Sample of the electrochemical synthesis process was analyzed by gas chromatography. From the result, it is found that the optimum conditions of the electrochemical synthesis process of carbon dioxide conversion into ethanol are voltage, concentration of sodium bicarbonate electrolyte solution and time of electrolysis are 3 volts, 0.4 M and 90 minutes with the ethanol concentration of 10.44%.

  20. Synthesis of graphene platelets by chemical and electrochemical route

    Energy Technology Data Exchange (ETDEWEB)

    Ramachandran, Rajendran; Felix, Sathiyanathan [Centre for Nanotechnology Research, VIT University, Vellore 632014, Tamil Nadu (India); Joshi, Girish M. [Materials Physics Division, School of Advanced Sciences, VIT University, Vellore 632014, Tamil Nadu (India); Raghupathy, Bala P.C., E-mail: balapraveen2000@yahoo.com [Centre for Nanotechnology Research, VIT University, Vellore 632014, Tamil Nadu (India); Research and Advanced Engineering Division (Materials), Renault Nissan Technology and Business Center India (P) Ltd., Chennai, Tamil Nadu (India); Jeong, Soon Kwan, E-mail: jeongsk@kier.re.kr [Climate Change Technology Research Division, Korea Institute of Energy Research, Yuseong-gu, Daejeon 305-343 (Korea, Republic of); Grace, Andrews Nirmala, E-mail: anirmalagrace@vit.ac.in [Centre for Nanotechnology Research, VIT University, Vellore 632014, Tamil Nadu (India); Climate Change Technology Research Division, Korea Institute of Energy Research, Yuseong-gu, Daejeon 305-343 (Korea, Republic of)

    2013-10-15

    Graphical abstract: A schematic showing the overall reduction process of graphite to reduced graphene platelets by chemical and electrochemical route. - Highlights: • Graphene was prepared by diverse routes viz. chemical and electrochemical methods. • NaBH{sub 4} was effective for removing oxygen functional groups from graphene oxide. • Sodium borohydride reduced graphene oxide (SRGO) showed high specific capacitance. • Electrochemical rendered a cheap route for production of graphene in powder form. - Abstract: Graphene platelets were synthesized from graphene oxide by chemical and electrochemical route. Under the chemical method, sodium borohydride and hydrazine chloride were used as reductants to produce graphene. In this paper, a novel and cost effective electrochemical method, which can simplify the process of reduction on a larger scale, is demonstrated. The electrochemical method proposed in this paper produces graphene in powder form with good yield. The atomic force microscopic images confirmed that the graphene samples prepared by all the routes have multilayers of graphene. The electrochemical process provided a new route to make relatively larger area graphene sheets, which will have interest for further patterning applications. Attempt was made to quantify the quantum of reduction using cyclic voltammetry and choronopotentiometry techniques on reduced graphene samples. As a measure in reading the specific capacitance values, a maximum specific capacitance value of 265.3 F/g was obtained in sodium borohydride reduced graphene oxide.

  1. Synthesis of graphene platelets by chemical and electrochemical route

    International Nuclear Information System (INIS)

    Ramachandran, Rajendran; Felix, Sathiyanathan; Joshi, Girish M.; Raghupathy, Bala P.C.; Jeong, Soon Kwan; Grace, Andrews Nirmala

    2013-01-01

    Graphical abstract: A schematic showing the overall reduction process of graphite to reduced graphene platelets by chemical and electrochemical route. - Highlights: • Graphene was prepared by diverse routes viz. chemical and electrochemical methods. • NaBH 4 was effective for removing oxygen functional groups from graphene oxide. • Sodium borohydride reduced graphene oxide (SRGO) showed high specific capacitance. • Electrochemical rendered a cheap route for production of graphene in powder form. - Abstract: Graphene platelets were synthesized from graphene oxide by chemical and electrochemical route. Under the chemical method, sodium borohydride and hydrazine chloride were used as reductants to produce graphene. In this paper, a novel and cost effective electrochemical method, which can simplify the process of reduction on a larger scale, is demonstrated. The electrochemical method proposed in this paper produces graphene in powder form with good yield. The atomic force microscopic images confirmed that the graphene samples prepared by all the routes have multilayers of graphene. The electrochemical process provided a new route to make relatively larger area graphene sheets, which will have interest for further patterning applications. Attempt was made to quantify the quantum of reduction using cyclic voltammetry and choronopotentiometry techniques on reduced graphene samples. As a measure in reading the specific capacitance values, a maximum specific capacitance value of 265.3 F/g was obtained in sodium borohydride reduced graphene oxide

  2. Electrochemical synthesis of polydiphenylamine nanofibrils through AAO template

    International Nuclear Information System (INIS)

    Zhao Yanchun; Chen Miao; Liu Xiang; Xu Tao; Liu Weimin

    2005-01-01

    Highly ordered polydiphenylamine (PDPA) nanofibrils arrays have been fabricated within the pores of porous anodic aluminum oxide (AAO) template membrane by electrochemical polymerization. The morphology of PDPA nanofibrils array was observed using transmission electron microscopy (TEM) and its electrochemical behavior and structure were examined by cyclic voltammetry, UV-vis spectroscopy and Fourier transmission infrared spectrum. The result of TEM revealed that the obtained PDPA nanofibrils had uniform and well-aligned array. The UV-vis spectroscopy and electrochemical experimental result indicated that the spatial restraint in the pores of AAO membrane is sufficient to induce the formation of more ordered PDPA chains in the AAO membrane

  3. Electrochemical synthesis of polydiphenylamine nanofibrils through AAO template

    Energy Technology Data Exchange (ETDEWEB)

    Yanchun, Zhao [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Miao, Chen [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Xiang, Liu [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Tao, Xu [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Weimin, Liu [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

    2005-06-15

    Highly ordered polydiphenylamine (PDPA) nanofibrils arrays have been fabricated within the pores of porous anodic aluminum oxide (AAO) template membrane by electrochemical polymerization. The morphology of PDPA nanofibrils array was observed using transmission electron microscopy (TEM) and its electrochemical behavior and structure were examined by cyclic voltammetry, UV-vis spectroscopy and Fourier transmission infrared spectrum. The result of TEM revealed that the obtained PDPA nanofibrils had uniform and well-aligned array. The UV-vis spectroscopy and electrochemical experimental result indicated that the spatial restraint in the pores of AAO membrane is sufficient to induce the formation of more ordered PDPA chains in the AAO membrane.

  4. Bio-electrochemical synthesis of commodity chemicals by ...

    Indian Academy of Sciences (India)

    2016-08-02

    Aug 2, 2016 ... be exploited in a bio-electrochemical system for current generation or to provide ..... fiber was desorbed directly to GC injector for 3 min. This ..... The authors are grateful to COMSATS Institute of Information. Technology ...

  5. Electrochemical synthesis of CORE-shell magnetic nanowires

    KAUST Repository

    Ovejero, Jesú s G.; Bran, Cristina; Vidal, Enrique Vilanova; Kosel, Jü rgen; Morales, Marí a P.; Vazquez, Manuel

    2015-01-01

    (Fe, Ni, CoFe) @ Au core-shell magnetic nanowires have been synthesized by optimized two-step potentiostatic electrodeposition inside self-assembled nanopores of anodic aluminium templates. The optimal electrochemical parameters (e.g., potential

  6. Synthesis and characterization of electrochemically-reduced graphene

    Indian Academy of Sciences (India)

    Keywords. Graphene; electrochemical deposition; heat treatment; conductivity. 1. Introduction ... solar cells (Wu et al 2008; Sima et al 2011), molecular gas sensors ... solved in deionized (DI) water to obtain 0·01 M of electrolyte solution (Su et ...

  7. Electrochemical synthesis of mesoporous Pt-Au binary alloys with tunable compositions for enhancement of electrochemical performance.

    Science.gov (United States)

    Yamauchi, Yusuke; Tonegawa, Akihisa; Komatsu, Masaki; Wang, Hongjing; Wang, Liang; Nemoto, Yoshihiro; Suzuki, Norihiro; Kuroda, Kazuyuki

    2012-03-21

    Mesoporous Pt-Au binary alloys were electrochemically synthesized from lyotropic liquid crystals (LLCs) containing corresponding metal species. Two-dimensional exagonally ordered LLC templates were prepared on conductive substrates from diluted surfactant solutions including water, a nonionic surfactant, ethanol, and metal species by drop-coating. Electrochemical synthesis using such LLC templates enabled the preparation of ordered mesoporous Pt-Au binary alloys without phase segregation. The framework composition in the mesoporous Pt-Au alloy was controlled simply by changing the compositional ratios in the precursor solution. Mesoporous Pt-Au alloys with low Au content exhibited well-ordered 2D hexagonal mesostructures, reflecting those of the original templates. With increasing Au content, however, the mesostructural order gradually decreased, thereby reducing the electrochemically active surface area. Wide-angle X-ray diffraction profiles, X-ray photoelectron spectra, and elemental mapping showed that both Pt and Au were atomically distributed in the frameworks. The electrochemical stability of mesoporous Pt-Au alloys toward methanol oxidation was highly improved relative to that of nonporous Pt and mesoporous Pt films, suggesting that mesoporous Pt-Au alloy films are potentially applicable as electrocatalysts for direct methanol fuel cells. Also, mesoporous Pt-Au alloy electrodes showed a highly sensitive amperometric response for glucose molecules, which will be useful in next-generation enzyme-free glucose sensors.

  8. Electrochemical Synthesis of Ammonia from Water and Nitrogen using a Pt/GDC/Pt Cell

    International Nuclear Information System (INIS)

    Kim, Jong Nam; Yoo, Chung-Yul; Joo, Jong Hoon; Yu, Ji Haeng; Sharma, Monika; Yoon, Hyung Chul; Jeoung, Hana; Song, Ki Chang

    2014-01-01

    Electrochemical ammonia synthesis from water and nitrogen using a Pt/GDC/Pt cell was experimentally investigated. Electrochemical analysis and ammonia synthesis in the moisture-saturated nitrogen environment were performed under the operating temperature range 400-600 .deg. C and the applied potential range OCV (Open Circuit Voltage)-1.2V. Even though the ammonia synthesis rate was augmented with the increase in the operating temperature (i.e.. increase in the applied current) under the constant potential, the faradaic efficiency was decreased because of the limitation of dissociative chemisorption of nitrogen on the Pt electrode. The maximum synthesis rate of ammonia was 3.67x10 -11 mols -1 cm -2 with 0.1% faradaic efficiency at 600 .deg. C

  9. Electrochemical Synthesis of Ammonia from Water and Nitrogen using a Pt/GDC/Pt Cell

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jong Nam; Yoo, Chung-Yul; Joo, Jong Hoon; Yu, Ji Haeng; Sharma, Monika; Yoon, Hyung Chul [Korea Institute of Energy Research, Daejeon (Korea, Republic of); Jeoung, Hana; Song, Ki Chang [Konyang University, Nonsan (Korea, Republic of)

    2014-02-15

    Electrochemical ammonia synthesis from water and nitrogen using a Pt/GDC/Pt cell was experimentally investigated. Electrochemical analysis and ammonia synthesis in the moisture-saturated nitrogen environment were performed under the operating temperature range 400-600 .deg. C and the applied potential range OCV (Open Circuit Voltage)-1.2V. Even though the ammonia synthesis rate was augmented with the increase in the operating temperature (i.e.. increase in the applied current) under the constant potential, the faradaic efficiency was decreased because of the limitation of dissociative chemisorption of nitrogen on the Pt electrode. The maximum synthesis rate of ammonia was 3.67x10{sup -11} mols{sup -1}cm{sup -2} with 0.1% faradaic efficiency at 600 .deg. C.

  10. Total synthesis of TMG-chitotriomycin based on an automated electrochemical assembly of a disaccharide building block.

    Science.gov (United States)

    Isoda, Yuta; Sasaki, Norihiko; Kitamura, Kei; Takahashi, Shuji; Manmode, Sujit; Takeda-Okuda, Naoko; Tamura, Jun-Ichi; Nokami, Toshiki; Itoh, Toshiyuki

    2017-01-01

    The total synthesis of TMG-chitotriomycin using an automated electrochemical synthesizer for the assembly of carbohydrate building blocks is demonstrated. We have successfully prepared a precursor of TMG-chitotriomycin, which is a structurally-pure tetrasaccharide with typical protecting groups, through the methodology of automated electrochemical solution-phase synthesis developed by us. The synthesis of structurally well-defined TMG-chitotriomycin has been accomplished in 10-steps from a disaccharide building block.

  11. Total synthesis of TMG-chitotriomycin based on an automated electrochemical assembly of a disaccharide building block

    Directory of Open Access Journals (Sweden)

    Yuta Isoda

    2017-05-01

    Full Text Available The total synthesis of TMG-chitotriomycin using an automated electrochemical synthesizer for the assembly of carbohydrate building blocks is demonstrated. We have successfully prepared a precursor of TMG-chitotriomycin, which is a structurally-pure tetrasaccharide with typical protecting groups, through the methodology of automated electrochemical solution-phase synthesis developed by us. The synthesis of structurally well-defined TMG-chitotriomycin has been accomplished in 10-steps from a disaccharide building block.

  12. Synthesis, characterization and electrochemical investigation of hetaryl chromium(0) aminocarbene complexes

    Czech Academy of Sciences Publication Activity Database

    Metelková, R.; Tobrman, T.; Kvapilová, Hana; Hoskovcová, I.; Ludvík, Jiří

    2012-01-01

    Roč. 82, SI (2012), s. 470-477 ISSN 0013-4686 R&D Projects: GA AV ČR IAA400400813 Institutional support: RVO:61388955 Keywords : Fischer aminocarbene complexes * synthesis * Electrochemical oxidation and reduction Subject RIV: CG - Electrochemistry Impact factor: 3.777, year: 2012

  13. Synthesis, characterization and electrochemical performance of Li 2 ...

    Indian Academy of Sciences (India)

    Positive electrodes; lithium metal silicates; electrical conductivity; cyclic performance ... Furthermore, electrochemical impedance spectra measurements are performed ... It was observed that Li–Li 2 Ni 0.4 Fe 0.6 SiO 4 battery has initial discharge ... Central Metallurgical Research and Development Institute (CMRDI), Tebbin, ...

  14. Synthesis and characterization of electrochemically-reduced graphene

    Indian Academy of Sciences (India)

    Graphene has superior electrical conductivity than graphite and other allotropes of carbon because of its high surface area and chemical tolerance. Electrochemically processed graphene sheets were obtained through the reduction of graphene oxide from hydrazine hydrate. The prepared samples were heated to different ...

  15. V2O5 xerogel-poly(ethylene oxide) hybrid material: Synthesis, characterization, and electrochemical properties

    International Nuclear Information System (INIS)

    Guerra, Elidia M.; Ciuffi, Katia J.; Oliveira, Herenilton P.

    2006-01-01

    In this work, we report the synthesis, characterization, and electrochemical properties of vanadium pentoxide xerogel-poly(ethylene oxide) (PEO) hybrid materials obtained by varying the average molecular weight of the organic component as well as the components' ratios. The materials were characterized by X-ray diffraction, ultraviolet/visible and infrared spectroscopies, thermogravimetric analysis, scanning electron microscopy, electron paramagnetic resonance, and cyclic voltammetry. Despite the presence of broad and low intensity peaks, the X-ray diffractograms indicate that the lamellar structure of the vanadium pentoxide xerogel is preserved, with increase in the interplanar spacing, giving evidence of a low-crystalline structure. We found that the electrochemical behaviour of the hybrid materials is quite similar to that found for the V 2 O 5 xerogel alone, and we verified that PEO leads to stabilization and reproducibility of the Li + electrochemical insertion/de-insertion into the V 2 O 5 xerogel structure, which makes these materials potential components of lithium ion batteries. - Graphical abstract: The synthesis, structural and electrochemical properties of vanadium pentoxide xerogel-poly(ethylene oxide) hybrid materials have been described. Despite the presence of broad and low intensity peaks, the X-ray diffractograms indicate that the lamellar structure of the vanadium pentoxide xerogel is preserved. The cyclic voltammetry technique demonstrated that PEO intercalation provides an improvement in the electrochemical properties, mainly with respect to the lithium electroinsertion process into the oxide matrix

  16. Synthesis and utilization of carbon nanotubes for fabrication of electrochemical biosensors

    International Nuclear Information System (INIS)

    Lawal, Abdulazeez T.

    2016-01-01

    Graphical abstract: Carbon nanotubes. - Highlights: • This review discusses synthesis and applications of carbon nanotubes sensors. • The review summarizes contributions of carbon nanotube to electrochemical biosensor. • Good electrical conductivity makes carbon nanotubes a good material for biosensors. • Carbon nanotubes promotes electron transfer that aids biosensing of biomolecules. - Abstract: This review summarizes the most recent contributions in the fabrication of carbon nanotubes-based electrochemical biosensors in recent years. It discusses the synthesis and application of carbon nanotubes to the assembly of carbon nanotube-based electrochemical sensors, its analytical performance and future expectations. An increasing number of reviews and publications involving carbon nanotubes sensors have been reported ever since the first design of carbon nanotube electrochemical biosensors. The large surface area and good electrical conductivity of carbon nanotubes allow them to act as “electron wire” between the redox center of an enzyme or protein and an electrode's surface, which make them very excellent material for the design of electrochemical biosensors. Carbon nanotubes promote the different rapid electron transfers that facilitate accurate and selective detection of cytochrome-c, β-nicotinamide adenine dinucleotide, hemoglobin and biomolecules, such as glucose, cholesterol, ascorbic acid, uric acid, dopamine pesticides, metals ions and hydrogen peroxide.

  17. Synthesis and utilization of carbon nanotubes for fabrication of electrochemical biosensors

    Energy Technology Data Exchange (ETDEWEB)

    Lawal, Abdulazeez T., E-mail: abdul.lawal@yahoo.com

    2016-01-15

    Graphical abstract: Carbon nanotubes. - Highlights: • This review discusses synthesis and applications of carbon nanotubes sensors. • The review summarizes contributions of carbon nanotube to electrochemical biosensor. • Good electrical conductivity makes carbon nanotubes a good material for biosensors. • Carbon nanotubes promotes electron transfer that aids biosensing of biomolecules. - Abstract: This review summarizes the most recent contributions in the fabrication of carbon nanotubes-based electrochemical biosensors in recent years. It discusses the synthesis and application of carbon nanotubes to the assembly of carbon nanotube-based electrochemical sensors, its analytical performance and future expectations. An increasing number of reviews and publications involving carbon nanotubes sensors have been reported ever since the first design of carbon nanotube electrochemical biosensors. The large surface area and good electrical conductivity of carbon nanotubes allow them to act as “electron wire” between the redox center of an enzyme or protein and an electrode's surface, which make them very excellent material for the design of electrochemical biosensors. Carbon nanotubes promote the different rapid electron transfers that facilitate accurate and selective detection of cytochrome-c, β-nicotinamide adenine dinucleotide, hemoglobin and biomolecules, such as glucose, cholesterol, ascorbic acid, uric acid, dopamine pesticides, metals ions and hydrogen peroxide.

  18. Electrochemical synthesis of CORE-shell magnetic nanowires

    KAUST Repository

    Ovejero, Jesús G.

    2015-04-16

    (Fe, Ni, CoFe) @ Au core-shell magnetic nanowires have been synthesized by optimized two-step potentiostatic electrodeposition inside self-assembled nanopores of anodic aluminium templates. The optimal electrochemical parameters (e.g., potential) have been firstly determined for the growth of continuous Au nanotubes at the inner wall of pores. Then, a magnetic core was synthesized inside the Au shells under suitable electrochemical conditions for a wide spectrum of single elements and alloy compositions (e.g., Fe, Ni and CoFe alloys). Novel opportunities offered by such nanowires are discussed particularly the magnetic behavior of (Fe, Ni, CoFe) @ Au core-shell nanowires was tested and compared with that of bare TM nanowires. These core-shell nanowires can be released from the template so, opening novel opportunities for biofunctionalization of individual nanowires.

  19. Synthesis and electrochemical study of Pt-based nanoporous materials

    International Nuclear Information System (INIS)

    Wang Jingpeng; Holt-Hindle, Peter; MacDonald, Duncan; Thomas, Dan F.; Chen Aicheng

    2008-01-01

    In the present work, a variety of Pt-based bimetallic nanostructured materials including nanoporous Pt, Pt-Ru, Pt-Ir, Pt-Pd and Pt-Pb networks have been directly grown on titanium substrates via a facile hydrothermal method. The as-fabricated electrodes were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction and electrochemical methods. The active surface areas of these nanoporous Pt-based alloy catalysts are increased by over 68 (Pt-Pd), 69 (Pt-Ru) and 113 (Pt-Ir) fold compared to a polycrystalline Pt electrode. All these synthesized nanoporous electrodes exhibit superb electrocatalytic performance towards electrochemical oxidation of methanol and formic acid. Among the five nanoporous Pt-based electrodes, the Pt-Ir shows the highest peak current density at +0.50 V, with 68 times of enhancement compared to the polycrystalline Pt for methanol oxidation, and with 86 times of enhancement in formic acid oxidation; whereas the catalytic activity of the nanoporous Pt-Pb electrode outperforms the other materials in formic acid oxidation at the low potential regions, delivering an enhanced current density by 280-fold compared to the polycrystalline Pt at +0.15 V. The new approach described in this study is suitable for synthesizing a wide range of bi-metallic and tri-metallic nanoporous materials, desirable for electrochemical sensor design and potential application in fuel cells

  20. Synthesis and electrochemical study of Pt-based nanoporous materials

    Energy Technology Data Exchange (ETDEWEB)

    Wang Jingpeng [Department of Chemistry, Lakehead University, Thunder Bay, Ontario P7B 5E1 (Canada); Department of Chemistry, University of Guelph, Guelph, Ontario N1G 2W1 (Canada); Holt-Hindle, Peter; MacDonald, Duncan [Department of Chemistry, Lakehead University, Thunder Bay, Ontario P7B 5E1 (Canada); Thomas, Dan F. [Department of Chemistry, University of Guelph, Guelph, Ontario N1G 2W1 (Canada); Chen Aicheng [Department of Chemistry, Lakehead University, Thunder Bay, Ontario P7B 5E1 (Canada)], E-mail: aicheng.chen@lakeheadu.ca

    2008-10-01

    In the present work, a variety of Pt-based bimetallic nanostructured materials including nanoporous Pt, Pt-Ru, Pt-Ir, Pt-Pd and Pt-Pb networks have been directly grown on titanium substrates via a facile hydrothermal method. The as-fabricated electrodes were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction and electrochemical methods. The active surface areas of these nanoporous Pt-based alloy catalysts are increased by over 68 (Pt-Pd), 69 (Pt-Ru) and 113 (Pt-Ir) fold compared to a polycrystalline Pt electrode. All these synthesized nanoporous electrodes exhibit superb electrocatalytic performance towards electrochemical oxidation of methanol and formic acid. Among the five nanoporous Pt-based electrodes, the Pt-Ir shows the highest peak current density at +0.50 V, with 68 times of enhancement compared to the polycrystalline Pt for methanol oxidation, and with 86 times of enhancement in formic acid oxidation; whereas the catalytic activity of the nanoporous Pt-Pb electrode outperforms the other materials in formic acid oxidation at the low potential regions, delivering an enhanced current density by 280-fold compared to the polycrystalline Pt at +0.15 V. The new approach described in this study is suitable for synthesizing a wide range of bi-metallic and tri-metallic nanoporous materials, desirable for electrochemical sensor design and potential application in fuel cells.0.

  1. Synthesis and electrochemical study of Pt-based nanoporous materials

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jingpeng [Department of Chemistry, Lakehead University, Thunder Bay, Ontario P7B 5E1 (Canada); Department of Chemistry, University of Guelph, Guelph, Ontario N1G 2W1 (Canada); Holt-Hindle, Peter; MacDonald, Duncan; Chen, Aicheng [Department of Chemistry, Lakehead University, Thunder Bay, Ontario P7B 5E1 (Canada); Thomas, Dan F. [Department of Chemistry, University of Guelph, Guelph, Ontario N1G 2W1 (Canada)

    2008-10-01

    In the present work, a variety of Pt-based bimetallic nanostructured materials including nanoporous Pt, Pt-Ru, Pt-Ir, Pt-Pd and Pt-Pb networks have been directly grown on titanium substrates via a facile hydrothermal method. The as-fabricated electrodes were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction and electrochemical methods. The active surface areas of these nanoporous Pt-based alloy catalysts are increased by over 68 (Pt-Pd), 69 (Pt-Ru) and 113 (Pt-Ir) fold compared to a polycrystalline Pt electrode. All these synthesized nanoporous electrodes exhibit superb electrocatalytic performance towards electrochemical oxidation of methanol and formic acid. Among the five nanoporous Pt-based electrodes, the Pt-Ir shows the highest peak current density at +0.50 V, with 68 times of enhancement compared to the polycrystalline Pt for methanol oxidation, and with 86 times of enhancement in formic acid oxidation; whereas the catalytic activity of the nanoporous Pt-Pb electrode outperforms the other materials in formic acid oxidation at the low potential regions, delivering an enhanced current density by 280-fold compared to the polycrystalline Pt at +0.15 V. The new approach described in this study is suitable for synthesizing a wide range of bi-metallic and tri-metallic nanoporous materials, desirable for electrochemical sensor design and potential application in fuel cells. (author)

  2. Polymer-directed synthesis of metal oxide-containing nanomaterials for electrochemical energy storage

    Science.gov (United States)

    Mai, Yiyong; Zhang, Fan; Feng, Xinliang

    2013-12-01

    Metal oxide-containing nanomaterials (MOCNMs) of controllable structures at the nano-scale have attracted considerable interest because of their great potential applications in electrochemical energy storage devices, such as lithium-ion batteries (LIBs) and supercapacitors. Among many structure-directing agents, polymers and macromolecules, including block copolymers (BCPs) and graphene, exhibit distinct advantages in the template-assisted synthesis of MOCNMs. In this feature article, we introduce the controlled preparation of MOCNMs employing BCPs and graphene as structure-directing agents. Typical synthetic strategies are presented for the control of structures and sizes as well as the improvement of physical properties and electrochemical performance of MOCNMs in LIBs and supercapacitors.

  3. Electrochemical Study of Bromide in the Presence of 1,3-Indandione. Application to the Electrochemical Synthesis of Bromo Derivatives of 1,3-Indandione

    OpenAIRE

    Nematollahi, D.; Akaberi, N.

    2001-01-01

    The electrochemical oxidation of bromide in the presence of 1,3-indandione (1) in water/acetic acid and methanol/acetic acid mixtures has been studied by cyclic voltammetry and controlled-potential coulometry. The results indicate the participation of 1,3-indandione in the bromination reaction. On the basis of the electroanalytical and preparative results a reaction mechanism including electron transfer, chemical reaction and regeneration of bromide was discussed. The electrochemical synthesi...

  4. Nanocrystalline CdTe thin films by electrochemical synthesis

    Directory of Open Access Journals (Sweden)

    Ramesh S. Kapadnis

    2013-03-01

    Full Text Available Cadmium telluride thin films were deposited onto different substrates as copper, Fluorine-doped tin oxide (FTO, Indium tin oxide (ITO, Aluminum and zinc at room temperature via electrochemical route. The morphology of the film shows the nanostructures on the deposited surface of the films and their growth in vertical direction. Different nanostructures developed on different substrates. The X-ray diffraction study reveals that the deposited films are nanocrystalline in nature. UV-Visible absorption spectrum shows the wide range of absorption in the visible region. Energy-dispersive spectroscopy confirms the formation of cadmium telluride.

  5. Facile electrochemical synthesis of tellurium nanorods and their photoconductive properties

    Energy Technology Data Exchange (ETDEWEB)

    Li, H.H. [Center for Photon Manufacturing Science and Technology, School of Materials Science and Engineering, Jiangsu University, Zhenjiang - 212013 (China); Zhang, P. [Dongguan University of Technology, Dongguan-523808 (China); School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou - 510275 (China); Liang, C.L. [Instrumental Analysis and Research Center, SunYat-sen University, Guangzhou - 510275 (China); Yang, J. [School of Materials Science and Engineering, Jiangsu University, Zhenjiang - 212013 (China); Zhou, M. [Center for Photon Manufacturing Science and Technology, School of Materials Science and Engineering, Jiangsu University, Zhenjiang - 212013 (China); The State Key Laboratory of Tribology, Tsinghua University, Beijing - 10084 (China); Lu, X.H. [School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou - 510275 (China); Hope, G.A. [School of Biomolecular and Physical Sciences, Griffith University, Nathan - Qld 4111 (Australia)

    2012-10-15

    Tellurium nanorods have been successfully fabricated by template and surfactant-free electrochemical technique from an aqueous solution at room temperature. The as-prepared tellurium nanorods were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectrometry, UV-vis spectroscopy and photoluminescence spectroscopy. Films based on tellurium nanorods were constructed to study the photoresponse and I-V curves. These photoresponse measurements demonstrate that tellurium nanorods exhibited enhanced conductivity under illumination compared to in the dark measurement. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Facile electrochemical synthesis of few layered graphene from discharged battery electrode and its

    Directory of Open Access Journals (Sweden)

    Santosh K. Tiwari

    2017-05-01

    Full Text Available A cost-effective, simple and non-hazardous route for synthesis of few-layered graphene from waste zinc carbon battery (ZCB electrodes via electrochemical expansion (ECE has been reported. In this synthesis, we have electrochemically exfoliated the graphene layers, by intercalating sodium dodecyl benzenesulfonate (SDBS surfactant into graphitic layers at different D.C. voltages with a constant SDBS concentration. The graphene sheets were isolated, purified and characterized by Transmission electron microscopy (TEM, Scanning electron microscopy (SEM, Fourier transform infrared spectrometry (FTIR, X-ray diffraction (XRD, Raman spectrometry, Ultraviolet absorption (UV, Selected area electron diffraction (SAED and Cyclic voltammetry. Best result was obtained at 4.5 V of D.C. A possible mechanism for the intercalation process has been proposed. A promising application of the produced material for supercapacitor application has also been explored in combination with polyaniline.

  7. One step paired electrochemical synthesis of iron and iron oxide nanoparticles

    Directory of Open Access Journals (Sweden)

    Ordoukhanian Juliet

    2016-09-01

    Full Text Available In this study, a new one step paired electrochemical method is developed for simultaneous synthesis of iron and iron oxide nanoparticles. iron and iron oxide are prepared as cathodic and anodic products from iron (ii sulfate aqueous solution in a membrane divided electrolytic cell by the pulsed current electrosynthesis. Because of organic solvent-free and electrochemical nature of the synthesis, the process could be considered as green and environmentally friendly. The reduction of energy consumption and low cost are the other significant advantages of this new method that would have a great application potential in the chemical industry. The nanostructure of prepared samples was characterized by Fourier transform infrared spectroscopy (FT-IR, X-ray diffraction (XRD, scanning electron microscopy (SEM and transmission electron microscopy (TEM. The magnetic properties were studied by vibrating sample magnetometer (VsM.

  8. Electrochemical synthesis of transition element complexes with carboxyl- and carbonyl-containing ligands

    International Nuclear Information System (INIS)

    Frolov, V.Yu.; Bolotin, S.N.; Panyushkin, V.T.

    2005-01-01

    Complexes of d- and f-elements (E = Cu, Ni, Zn, Nd, Tb, Pr, Gd, Er) with carboxyl- and carbonyl-containing ligands were synthesized by the electrochemical method. The products were characterized by elemental analysis, thermal gravimetric analysis and IR spectra. The influence exerted by a number of factors on the process course was studied. The dependence of the electro synthesis parameters on the composition of the forming compounds was established. A new method for anodic synthesis of these compounds was developed [ru

  9. Novel Electrochemical Synthesis of Polypyrrole/Ag Nanocomposite and Its Electrocatalytic Performance towards Hydrogen Peroxide Reduction

    OpenAIRE

    Ruma Gupta; Kavitha Jayachandran; J. S. Gamare; B. Rajeshwari; Santosh K. Gupta; J. V. Kamat

    2015-01-01

    A simple electrochemical method of synthesis of polypyrrole/silver (PPy/Ag) nanocomposite is presented. The method is based on potentiodynamic polymerization of pyrrole followed by electrodeposition of silver employing a single potentiostatic pulse. The synthesized PPy film has embedded Ag nanocubes. The morphology and structure of the resulting nanocomposite were characterized by field emission scanning electron microscopy and X-ray diffraction. Electron paramagnetic resonance studies showed...

  10. Electrochemical synthesis of polypyrrole on ferrous and non-ferrous metals from sweet aqueous electrolytic medium

    International Nuclear Information System (INIS)

    Bazzaoui, M.; Martins, J.I.; Reis, T.C.; Bazzaoui, E.A.; Nunes, M.C.; Martins, L.

    2005-01-01

    The electrodeposition of polypyrrole (PPy) on oxidizable metals such as aluminum and iron has been achieved in aqueous medium of saccharin and pyrrole. Scanning electron microscopy and X-ray photoelectron spectroscopy analysis reveal a good homogeneity of the obtained PPy film. The electrochemical synthesis of PPy coating has been achieved successfully under potentiodynamic, galvanostatic and potentiostatic techniques. The corrosion experiments performed in HCl show that the PPy coating increases the corrosion potential and decreases the corrosion current density

  11. Electrochemical synthesis of nanosized TiO2 nanopowder involving choline chloride based ionic liquids

    International Nuclear Information System (INIS)

    Anicai, Liana; Petica, Aurora; Patroi, Delia; Marinescu, Virgil; Prioteasa, Paula; Costovici, Stefania

    2015-01-01

    Highlights: • TiO 2 nanopowder electrochemically prepared using choline chloride based ionic liquids. • The new proposed method allowed high anodic synthesis efficiencies of minimum 92%. • High surface area of the electrochemically synthesized titania nanopowders. • Enhanced photocatalytic activity. - Abstract: The paper presents some experimental results regarding the electrochemical synthesis of TiO 2 nanopowders through anodic dissolution of Ti metal in choline chloride based eutectic mixtures (DES). A detailed characterization of the obtained titania has been performed, using various techniques, including XRD, Raman spectroscopy, XPS, SEM associated with EDX analysis, BET and UV–vis diffuse reflectance spectra. The anodic behavior of Ti electrode in DES has been also investigated. The photoreactivity of the synthesized materials was evaluated for the degradation of Orange II dye under UV (λ = 365 nm) and visible light irradiation. An anodic synthesis efficiency of minimum 92% has been determined. The as-synthesized TiO 2 showed amorphous structure and a calcination post-treatment at temperatures between 400 and 600 °C yielded anatase. The anodically obtained nanocrystalline oxides have crystallite sizes of 8–18 nm, a high surface area and enhanced photocatalytic effect

  12. Electrochemical synthesis of nanosized TiO{sub 2} nanopowder involving choline chloride based ionic liquids

    Energy Technology Data Exchange (ETDEWEB)

    Anicai, Liana, E-mail: lanicai@itcnet.ro [POLITEHNICA University of Bucharest, Center of Surface Science and Nanotechnology, Splaiul Independentei 313, Bucharest, 060042 (Romania); Petica, Aurora [Leather and Footwear Research Institute (ICPI), Ion Minulescu 93, Bucharest, 031215 (Romania); Patroi, Delia; Marinescu, Virgil; Prioteasa, Paula [INCDIE ICPE-Advanced Research, Splaiul Unirii 313, Bucharest (Romania); Costovici, Stefania [POLITEHNICA University of Bucharest, Center of Surface Science and Nanotechnology, Splaiul Independentei 313, Bucharest, 060042 (Romania)

    2015-09-15

    Highlights: • TiO{sub 2} nanopowder electrochemically prepared using choline chloride based ionic liquids. • The new proposed method allowed high anodic synthesis efficiencies of minimum 92%. • High surface area of the electrochemically synthesized titania nanopowders. • Enhanced photocatalytic activity. - Abstract: The paper presents some experimental results regarding the electrochemical synthesis of TiO{sub 2} nanopowders through anodic dissolution of Ti metal in choline chloride based eutectic mixtures (DES). A detailed characterization of the obtained titania has been performed, using various techniques, including XRD, Raman spectroscopy, XPS, SEM associated with EDX analysis, BET and UV–vis diffuse reflectance spectra. The anodic behavior of Ti electrode in DES has been also investigated. The photoreactivity of the synthesized materials was evaluated for the degradation of Orange II dye under UV (λ = 365 nm) and visible light irradiation. An anodic synthesis efficiency of minimum 92% has been determined. The as-synthesized TiO{sub 2} showed amorphous structure and a calcination post-treatment at temperatures between 400 and 600 °C yielded anatase. The anodically obtained nanocrystalline oxides have crystallite sizes of 8–18 nm, a high surface area and enhanced photocatalytic effect.

  13. JV Task-121 Electrochemical Synthesis of Nitrogen Fertilizers

    Energy Technology Data Exchange (ETDEWEB)

    Junhua Jiang; Ted Aulich

    2008-11-30

    An electrolytic renewable nitrogen fertilizer process that utilizes wind-generated electricity, N{sub 2} extracted from air, and syngas produced via the gasification of biomass to produce nitrogen fertilizer ammonia was developed at the University of North Dakota Energy & Environmental Research Center. This novel process provides an important way to directly utilize biosyngas generated mainly via the biomass gasification in place of the high-purity hydrogen which is required for Haber Bosch-based production of the fertilizer for the production of the widely used nitrogen fertilizers. Our preliminary economic projection shows that the economic competitiveness of the electrochemical nitrogen fertilizer process strongly depends upon the cost of hydrogen gas and the cost of electricity. It is therefore expected the cost of nitrogen fertilizer production could be considerably decreased owing to the direct use of cost-effective 'hydrogen-equivalent' biosyngas compared to the high-purity hydrogen. The technical feasibility of the electrolytic process has been proven via studying ammonia production using humidified carbon monoxide as the hydrogen-equivalent vs. the high-purity hydrogen. Process optimization efforts have been focused on the development of catalysts for ammonia formation, electrolytic membrane systems, and membrane-electrode assemblies. The status of the electrochemical ammonia process is characterized by a current efficiency of 43% using humidified carbon monoxide as a feedstock to the anode chamber and a current efficiency of 56% using high-purity hydrogen as the anode gas feedstock. Further optimization of the electrolytic process for higher current efficiency and decreased energy consumption is ongoing at the EERC.

  14. Synthesis and electrochemical characterization of stabilized nickel nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Dominguez-Crespo, M.A.; Ramirez-Meneses, E.; Torres Huerta, A.M. [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, CICATA-IPN Unidad Altamira, Carretera Tampico-Puerto Industrial, C.P. 89600 Altamira, Tamaulipas (Mexico); Montiel-Palma, V. [Centro de Investigaciones Quimicas, Universidad Autonoma del Estado de Morelos, Av. Universidad 1001, Colonia Chamilpa, C.P.62201 Cuernavaca, Morelos (Mexico); Dorantes Rosales, H. [Departamento de Metalurgia, Escuela Superior de Ingenieria Quimica e Industrias Extractivas - IPN, C.P. 07300, D.F. (Mexico)

    2009-02-15

    Nickel stabilized nanoparticles produced by an organometallic approach (Chaudret's method) starting from the complex Ni(1,5-COD){sub 2} were used as electrode materials for hydrogen evolution in NaOH at two temperatures (298 and 323 K). The synthesis of the nickel nanoparticles was performed in the presence of two different stabilizers, 1,3-diaminopropane (DAP) and anthranilic acid (AA), by varying the molar ratios (1:1, 1:2 and 1:5 metal:ligand) in order to evaluate their influence on the shape, dispersion, size and electrocatalytic activity of the metallic particles. The presence of an appropriate amount of stabilizer is an effective alternative to the synthesis of small monodispersed metal nanoparticles with diameters around 5 and 8 nm for DAP and AA, respectively. The results are discussed in terms of morphology and the surface state of the nanoparticles. The importance of developing a well-controlled synthetic method which results in higher performances of the resulting nanoparticles is highlighted. Herein we found that the performance with respect to the HER of the Ni electrodes dispersed on a carbon black Vulcan substrate is active and comparable to that reported in the literature for the state-of-the-art electrocatalysts. Appreciable cathodic current densities of {proportional_to}240 mA cm{sup -2} were measured with highly dispersed nickel particles (Ni-5{sub DAP}). This work demonstrates that the aforementioned method can be extended to the preparation of highly active stabilized metal particles without inhibiting the electron transfer for the HER reaction, and it could also be applied to the synthesis of bimetallic nanoparticles. (author)

  15. Electrochemical method for rapid synthesis of Zinc Pentacyanonitrosylferrate Nanotubes

    Directory of Open Access Journals (Sweden)

    Rogaieh Bargeshadi

    2014-10-01

    Full Text Available In this paper, a rapid and simple approach was developed for the preparation of zinc pentacyanonitrosylferrate nanotubes (ZnPCNF NTs within the cylindrical pores of anodic aluminum oxide (AAO template by electrochemical method. The AAO was fabricated in two steps anodizing from aluminum foil. The first anodization of aluminum foil was performed in 0.2 mol L-1 H2C2O4 followed by removal of the formed porous oxide film by a solution of 6 wt% of phosphoric acid. The second anodization step was then performed using the same conditions as the previous step. Scanning electron microscope (SEM and X-ray diffraction (XRD method were employed to characterize the resulting highly oriented uniform hollow tube array which its diameter was in the range of 25-75 nm depending on the applied voltage and the length of nanotubes was equal to the thickness of AAO which was about 2 m. The growth properties of the ZnPCNF NTs array film can be achieved by controlling the structure of the template and applied potential across the cell.

  16. Synthesis of cationic star polymers by simplified electrochemically mediated ATRP

    Directory of Open Access Journals (Sweden)

    P. Chmielarz

    2016-10-01

    Full Text Available Cyclodextrin-based cationic star polymers were synthesized using β-cyclodextrin (β-CD core, and 2-(dimethylamino ethyl methacrylate (DMAEMA as hydrophilic arms. Star-shaped polymers were prepared via a simplified electrochemically mediated ATRP (seATRP under potentiostatic and galvanostatic conditions. The polymerization results showed molecular weight (MW evolution close to theoretical values, and maintained narrow molecular weight distribution (MWD of obtained stars. The rate of the polymerizations was controlled by applying more positive potential values thereby suppressing star-star coupling reactions. Successful chain extension of the ω-functional arms with a hydrophobic n-butyl acrylate (BA formed star block copolymers and confirmed the living nature of the β-CD-PDMAEMA star polymers prepared by seATRP. Novelty of this work is that the β-CD-PDMAEMA-b-PBA cationic star block copolymers were synthesized for the first time via seATRP procedure, utilizing only 40 ppm of catalyst complex. The results from 1H NMR spectral studies support the formation of cationic star (copolymers.

  17. Electrolytes and Electrodes for Electrochemical Synthesis of Ammonia

    DEFF Research Database (Denmark)

    Lapina, Alberto

    In order to make Denmark independent of fossil fuels by 2050 the share of renewable energy in electricity production, in particular wind energy, is expected to increase significantly. Since the power output of renewable energy sources heavily fluctuates over time there is a pressing need to find...... technology is based on the Haber-Bosch process, which is energy intensive and requires large-scale plants. One possible way to produce ammonia from sustainable electricity, nitrogen and hydrogen/water is using an electrochemical cell. This thesis studies a number of electrolytes and electrocatalysts...... state proton conductors are briefly reviewed and defect chemistry and partial conductivities of Y-doped BaZrO3-BaCeO3 solid solutions are studied as a function of temperature, pH2O and chemical compositions by means of defect chemistry modelling. BaCe0.2Zr0.6Y0.2O2.9 (BCZY26) is chosen as electrolyte...

  18. Fluorinated Phosphorene: Electrochemical Synthesis, Atomistic Fluorination, and Enhanced Stability.

    Science.gov (United States)

    Tang, Xian; Liang, Weiyuan; Zhao, Jinlai; Li, Zhongjun; Qiu, Meng; Fan, Taojian; Luo, Crystal Shaojuan; Zhou, Ye; Li, Yu; Guo, Zhinan; Fan, Dianyuan; Zhang, Han

    2017-12-01

    Phosphorene has attracted great interest due to its unique electronic and optoelectronic properties owing to its tunable direct and moderate band-gap in association with high carrier mobility. However, its intrinsic instability in air seriously hinders its practical applications, and problems of technical complexity and in-process degradation exist in currently proposed stabilization strategies. A facile pathway in obtaining and stabilizing phosphorene through a one-step, ionic liquid-assisted electrochemical exfoliation and synchronous fluorination process is reported in this study. This strategy enables fluorinated phosphorene (FP) to be discovered and large-scale, highly selective few-layer FP (3-6 atomic layers) to be obtained. The synthesized FP is found to exhibit unique morphological and optical characteristics. Possible atomistic fluorination configurations of FP are revealed by core-level binding energy shift calculations in combination with spectroscopic measurements, and the results indicate that electrolyte concentration significantly modulates the fluorination configurations. Furthermore, FP is found to exhibit enhanced air stability thanks to the antioxidation and antihydration effects of the introduced fluorine adatoms, and demonstrate excellent photothermal stability during a week of air exposure. These findings pave the way toward real applications of phosphorene-based nanophotonics. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Towards a carbon independent and CO2-free electrochemical membrane process for NH3 synthesis.

    Science.gov (United States)

    Kugler, K; Ohs, B; Scholz, M; Wessling, M

    2014-04-07

    Ammonia is exclusively synthesized by the Haber-Bosch process starting from precious carbon resources such as coal or CH4. With H2O, H2 is produced and with N2, NH3 can be synthesized at high pressures and temperatures. Regrettably, the carbon is not incorporated into NH3 but emitted as CO2. Valuable carbon sources are consumed which could be used otherwise when carbon sources become scarce. We suggest an alternative process concept using an electrochemical membrane reactor (ecMR). A complete synthesis process with N2 production and downstream product separation is presented and evaluated in a multi-scale model to quantify its energy consumption. A new micro-scale ecMR model integrates mass, species, heat and energy balances with electrochemical conversions allowing further integration into a macro-scale process flow sheet. For the anodic oxidation reaction H2O was chosen as a ubiquitous H2 source. Nitrogen was obtained by air separation which combines with protons from H2O to give NH3 using a hypothetical catalyst recently suggested from DFT calculations. The energy demand of the whole electrochemical process is up to 20% lower than the Haber-Bosch process using coal as a H2 source. In the case of natural gas, the ecMR process is not competitive under today's energy and resource conditions. In future however, the electrochemical NH3 synthesis might be the technology-of-choice when coal is easily accessible over natural gas or limited carbon sources have to be used otherwise but for the synthesis of the carbon free product NH3.

  20. Nanostructured inorganic materials: Synthesis and associated electrochemical properties

    Science.gov (United States)

    Yau, Shali Zhu

    Synthetic strategy for preparing potential battery materials at low temperature was developed. Magnetite (Fe3O4), silver hollandnite (AgxMn8O16), magnesium manganese oxide (MgxMnO 2˙yH2O), and silver vanadium phosphorous oxide (Ag 2VO2PO4) were studied. Magnetite (Fe3O4) was prepared by coprecipitation induced by triethylamine from aqueous iron(II) and iron(III) chloride solutions of varying concentrations. Variation of the iron(II) and iron(III) concentrations results in crystallite size control of the Fe3O4 products. Materials characterization of the Fe3O4 samples is reported, including Brunauer-Emmitt-Teller (BET) surface area, x-ray powder diffraction (XRD), transmission electron microscopy (TEM), particle size, and saturation magnetization results. A strong correlation between discharge capacity and voltage recovery behavior versus crystallite size was observed when tested as an electrode material in lithium electrochemical cells. Silver hollandite (AgxMn8O16) was successfully synthesized through a low temperature reflux reaction. The crystallite size and silver content of AgxMn8O16 by varying the reactant ratio of silver permanganate (AgMnO4) and manganese sulfate monohydrate (MnSO4˙H2O). Silver hollandite was characterized by Brunauer-Emmitt-Teller (BET) surface area, inductively coupled plasma-optical emission (ICP-OES) spectrometry, helium pycnometry, simultaneous thermogravimetric analysis/differential scanning calorimetry (TGA/DSC), and x-ray powder diffraction (XRD). The crystallite size showed a strong correlation with silver content, BET surface area, and particle sizes. The silver hollandite cathode showed good discharge capacity retention in 30 cycles of discharge-charge. There were a good relationship between crystallite size and rate capability and pulse ability. Magnesium manganese oxide (MgxMnO2˙yH 2O) was made by redox reaction by mixing sodium hydroxide (NaOH), manganese sulfate monohydrate (MnSO4˙HO2), and potassium persulfate (K2S2O8

  1. Investigation of electrochemical synthesis of ferrate, Part I: Electrochemical behavior of iron and its several alloys in concentrated alkaline solutions

    Directory of Open Access Journals (Sweden)

    Čekerevac Milan I.

    2009-01-01

    Full Text Available In recent years, considerable attention has been paid to various applications of Fe(VI due to its unique properties such as oxidizing power, selective reactivity, stability of the salt, and non-toxic decomposition by-products of ferric ion. In environmental remediation processes, Fe(VI has been proposed as green oxidant, coagulant, disinfectant, and antifoulant. Therefore, it is considered as a promising multi-purpose water treatment chemical. Fe(VI has also potential applications in electrochemical energy source, as 'green cathode'. The effectiveness of ferrate as a powerful oxidant in the entire pH range, and its use in environmental applications for the removal of wide range of contaminants has been well documented by several researchers. There is scientific evidence that ferrate can effectively remove arsenic, algae, viruses, pharmaceutical waste, and other toxic heavy metals. Although Fe(VI was first discovered in early eighteen century, detailed studies on physical and chemical properties of Fe(VI had to wait until efficient synthetic and analytical methods of Fe(VI were developed by Schreyer et al. in the 1950s. Actually, there have been developed three ways for the preparation of Fe(VI compounds : the wet oxidation of Fe(II and Fe(III compounds, the dry oxidation of the same, and the electrochemistry method, mainly based on the trans passive oxidation of iron. High purity ferrates Fe(VI can be generated when electrode of the pure iron metal or its alloys are anodized in concentrated alkaline solution. It is known that the efficiency of electrochemical process of Fe(VI production depends on many factors such as current density, composition of anode material, types of electrolyte etc. In this paper, the electrochemical synthesis of ferrate(VI solution by the anodic dissolution of iron and its alloys in concentrated water solution of NaOH and KOH is investigated. The process of transpassive dissolution of iron to ferrate(VI was studied by

  2. Water-based synthesis of hydrophobic ionic liquids for high-energy electrochemical devices

    International Nuclear Information System (INIS)

    Montanino, Maria; Alessandrini, Fabrizio; Passerini, Stefano; Appetecchi, Giovanni Battista

    2013-01-01

    Highlights: ► Water-based synthesis of ionic liquids with high yield. ► Full recycling of reagents. ► High purity pyrrolidinium-based ionic liquids with exceptional electrochemical stability window. ► Lithium plating from pyrrolidinium-based ionic liquids. -- Abstract: In this work is described an innovative synthesis route for hydrophobic ionic liquids (ILs) composed of N-methyl-N-alkylpyrrolidinium (or piperidinium) or imidazolium or tetralkylammonium cations and (perfluoroalkylsulfonyl)imide, ((C n F 2n+1 SO 2 )(C m F 2m+1 SO 2 )N − ), anions. This synthesis does not require the use of any environmental unfriendly solvent such as acetone, acetonitrile or halogen-containing compounds, which is not welcome in industrial applications. Only water is used as the process solvent throughout the entire process. In addition, the commonly used iodine-containing reagents were replaced by the cheaper, more chemically stable and less toxic bromine-containing compounds. A particular care was devoted to the development of the purification route, which is especially important for ILs to be used in high-energy electrochemical devices such as high voltage supercapacitors and lithium batteries. The effect of the reaction temperature, the time and the stoichiometry in the various steps of the synthesis have been investigated in detail. This novel procedure allowed obtaining ultrapure (>99.9 wt.%), clear, colourless, inodorous ILs with an overall yield above 92 wt.% and moisture content below 1 ppm. NMR measurements were run to confirm the chemical structure whereas elemental analysis and electrochemical tests were performed to check the purity of the synthesized ILs

  3. Microwave assisted synthesis of MnO2 on nickel foam-graphene for electrochemical capacitor

    International Nuclear Information System (INIS)

    Bello, A.; Fashedemi, O.O.; Fabiane, M.; Lekitima, J.N.; Ozoemena, K.I.; Manyala, N.

    2013-01-01

    Highlights: •Three-dimensional synthesis of graphene using CVD. •Hydrothermal deposition (microwave irradiation) of MnO 2 on graphene. •Morphologies of the composite reveals flower-like nanostructures of MnO 2 on graphene. •Composite exhibit excellent electrochemical performance. -- Abstract: A green chemistry approach (hydrothermal microwave irradiation) has been used to deposit manganese oxide on nickel foam-graphene. The 3D graphene was synthesized using nickel foam template by chemical vapor deposition (CVD) technique. Raman spectroscopy, X-ray diffraction (XRD), scanning electron and transmission electron microscopies (SEM and TEM) have been used to characterize structure and surface morphology of the composite, respectively. The Raman spectroscopy measurements on the samples reveal that 3D graphene consists of mostly few layers with low defect density. The composite was tested in a three electrode configuration for electrochemical capacitor, and exhibited a specific capacitance of 305 F g −1 at a current density of 1 A g −1 and showed excellent cycling stability. The obtained results demonstrate that microwave irradiation technique could be a promising approach to synthesis graphene based functional materials for electrochemical applications

  4. The self-assembly of redox active peptides: Synthesis and electrochemical capacitive behavior.

    Science.gov (United States)

    Piccoli, Julia P; Santos, Adriano; Santos-Filho, Norival A; Lorenzón, Esteban N; Cilli, Eduardo M; Bueno, Paulo R

    2016-05-01

    The present work reports on the synthesis of a redox-tagged peptide with self-assembling capability aiming applications in electrochemically active capacitive surfaces (associated with the presence of the redox centers) generally useful in electroanalytical applications. Peptide containing ferrocene (fc) molecular (redox) group (Ac-Cys-Ile-Ile-Lys(fc)-Ile-Ile-COOH) was thus synthesized by solid phase peptide synthesis (SPPS). To obtain the electrochemically active capacitive interface, the side chain of the cysteine was covalently bound to the gold electrode (sulfur group) and the side chain of Lys was used to attach the ferrocene in the peptide chain. After obtaining the purified redox-tagged peptide, the self-assembly and redox capability was characterized by cyclic voltammetry (CV) and electrochemical impedance-based capacitance spectroscopy techniques. The obtained results confirmed that the redox-tagged peptide was successfully attached by forming an electroactive self-assembled monolayer onto gold electrode. The design of redox active self-assembly ferrocene-tagged peptide is predictably useful in the development of biosensor devices precisely to detect, in a label-free platform, those biomarkers of clinical relevance. © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 357-367, 2016. © 2016 Wiley Periodicals, Inc.

  5. Recent progress in layered double hydroxide based materials for electrochemical capacitors: design, synthesis and performance.

    Science.gov (United States)

    Zhao, Mingming; Zhao, Qunxing; Li, Bing; Xue, Huaiguo; Pang, Huan; Chen, Changyun

    2017-10-19

    As representative two-dimensional (2D) materials, layered double hydroxides (LDHs) have received increasing attention in electrochemical energy storage and conversion because of the facile tunability between their composition and morphology. The high dispersion of active species in layered arrays, the simple exfoliation into monolayer nanosheets and chemical modification offer the LDHs an opportunity as active electrode materials in electrochemical capacitors (ECs). LDHs are favourable in providing large specific surface areas, good transport features as well as attractive physicochemical properties. In this review, our purpose is to provide a detailed summary of recent developments in the synthesis and electrochemical performance of the LDHs. Their composites with carbon (carbon quantum dots, carbon black, carbon nanotubes/nanofibers, graphene/graphene oxides), metals (nickel, platinum, silver), metal oxides (TiO 2 , Co 3 O 4 , CuO, MnO 2 , Fe 3 O 4 ), metal sulfides/phosphides (CoS, NiCo 2 S 4 , NiP), MOFs (MOF derivatives) and polymers (PEDOT:PSS, PPy (polypyrrole), P(NIPAM-co-SPMA) and PET) are also discussed in this review. The relationship between structures and electrochemical properties as well as the associated charge-storage mechanisms is discussed. Moreover, challenges and prospects of the LDHs for high-performance ECs are presented. This review sheds light on the sustainable development of ECs with LDH based electrode materials.

  6. Synthesis and characterization of a nanocomposite of goethite nanorods and reduced graphene oxide for electrochemical capacitors

    International Nuclear Information System (INIS)

    Shou Qingliang; Cheng Jipeng; Zhang Li; Nelson, Bradley J.; Zhang Xiaobin

    2012-01-01

    We report a one-step synthesis of a nanocomposite of goethite (α-FeOOH) nanorods and reduced graphene oxide (RGO) using a solution method in which ferrous cations serve as a reducing agent of graphite oxide (GO) to graphene and a precursor to grow goethite nanorods. As-prepared goethite nanorods have an average length of 200 nm and a diameter of 30 nm and are densely attached on both sides of the RGO sheets. The electrochemical properties of the nanocomposite were characterized by cyclic voltammetry (CV) and chronopotentiometry (CP) charge–discharge tests. The results showed that goethite/RGO composites have a high electrochemical capacitance of 165.5 F g −1 with an excellent recycling capability making the material promising for electrochemical capacitors. - Graphical abstract: The reduced graphene oxide sheets are decorated with goethite nanorods. The as-prepared composite exhibits a high electrochemical capacitance with good recycling capability, which is promising for supercapacitor applications. Higlights: ► Ferrous ions act as reductant of graphite oxide and precursor of goethite nanorods. ► Goethite nanorods are attached on both sides of the reduced graphene oxide sheets. ► Composite exhibits a high specific capacitance and a good recycling capability. ► Composite is promising for supercapacitor applications.

  7. Electrochemical synthesis of poly(pyrrole-co-o-anisidine)/chitosan composite films

    Science.gov (United States)

    Yalçınkaya, Süleyman; Çakmak, Didem

    2017-05-01

    In this study, poly(pyrrole-co-o-anisidine)/chitosan composite films were electrochemically synthesized in various monomers feed ratio (pyrrole: o-anisidine; 9:1, 7:3, 1:1, 3:7 and 1:9) of pyrrole and o-anisidine on the platinum electrode. Electrochemical synthesis of the composite films was carried out via cyclic voltammetry technique. They were characterized by FT-IR, cyclic voltammetry, SEM micrographs, digital images, TGA and DSC techniques. The SEM results indicated that the particle size of the composite decreased with increasing o-anisidine ratio and the films became more likely to be smooth morphology. The TGA results proved that the film of the composite with 1:1 ratio showed highest final degradation temperature and lowest weight loss (83%) compared to copolymer and 9:1 1:9 composite films. The 1:1 composite film had higher thermal stability than copolymer and the other composite films (9:1 1:9). Meanwhile, electrochemical studies exhibited that the 1/9 composite film had good electrochemical stability as well.

  8. One-step electrochemical synthesis and photoelectric conversion of a ZnO/Se/RGO composite

    International Nuclear Information System (INIS)

    Wang, Lei; Zhang, Chunyan; Zhang, Shengyi; Niu, Helin; Song, Jiming; Mao, Changjie; Jin, Baokang; Tian, Yupeng

    2015-01-01

    Using Zn(NO 3 ) 2 , H 2 SeO 3 and graphene oxide as precursors, the zinc oxide/selenium/reduced graphene oxide (ZnO/Se/RGO) composite was facilely electrodeposited on the surface of indium tin oxide glass. The conditions for electrochemical synthesis such as electrodeposition potential and electrolyte composition were studied. The morphology and crystallization of the products as-prepared were characterized using scanning electron microscopy (SEM) and x-ray diffractometry (XRD) respectively. The light absorption and conductivity of the products were studied by UV-visible spectroscopy (UV-vis) and electrochemical impedance spectroscopy (EIS). Based on a series of experimental results, the photoelectrical conversion mechanism and effect factors of the products were explored. By means of synergistic action of n-type ZnO, p-type Se and conductive RGO, the ZnO/Se/RGO composite showed excellent photoelectric conversion under visible light irradiation. (paper)

  9. Electrochemical synthesis and characterization of stable colloidal suspension of graphene using two-electrode cell system

    Energy Technology Data Exchange (ETDEWEB)

    Danial, Wan Hazman, E-mail: hazmandanial@gmail.com; Majid, Zaiton Abdul, E-mail: zaiton@kimia.fs.utm.my; Aziz, Madzlan [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia (UTM), 81310 Skudai, Johor (Malaysia); Chutia, Arunabhiram [Institute of Fluid Sciences, Tohoku University, Sendai 980-8577 (Japan); Sahnoun, Riadh [Ibnu Sina Institute for Fundamental Science Studies, Universiti Teknologi Malaysia (UTM), 81310 Skudai, Johor (Malaysia)

    2015-07-22

    The present work reports the synthesis and characterization of graphene via electrochemical exfoliation of graphite rod using two-electrode system assisted by Sodium Dodecyl Sulphate (SDS) as a surfactant. The electrochemical process was carried out with sequence of intercalation of SDS onto the graphite anode followed by exfoliation of the SDS-intercalated graphite electrode when the anode was treated as cathode. The effect of intercalation potential from 5 V to 9 V and concentration of the SDS surfactant of 0.1 M and 0.01 M were investigated. UV-vis Spectroscopic analysis indicated an increase in the graphene production with higher intercalation potential. Transmission Electron Microscopy (TEM) analysis showed a well-ordered hexagonal lattice of graphene image and indicated an angle of 60° between two zigzag directions within the honeycomb crystal lattice. Raman spectroscopy analysis shows the graphitic information effects after the exfoliation process.

  10. Synthesis and electrochemical properties of peripheral carbazole functional Ter(9,9-spirobifluorene)s.

    Science.gov (United States)

    Tang, Shi; Liu, Meirong; Gu, Cheng; Zhao, Yang; Lu, Ping; Lu, Dan; Liu, Linlin; Shen, Fangzhong; Yang, Bing; Ma, Yuguang

    2008-06-06

    A facile approach for synthesis of spirobifluorene trimers with peripheral carbazole functional groups by utilizing Suzuki coupling as the key reaction has been developed. These novel compounds exhibit blue emission with high quantum yields in solution and thin films, and excellent spectral stability upon photoirradiation and annealing in air. By the introduction of carbazole groups, the oxidation potentials of spirobifluorene trimers S TCPC-6 and STCPC-4 were significantly lower than that of model compound STHPH without peripheral carbazole groups, which reflect that the title compounds process higher HOMO energy level and better hole-injection ability. Highly luminescent films were obtained by electrochemical coupling between carbazole units. Pure blue-emission single-layer LEDs based on electrochemical deposition films as light emitting layers were achieved.

  11. Synthesis, photophysical and electrochemical properties of water–soluble phthalocyanines bearing 8-hydroxyquinoline-5-sulfonicacid derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Günsel, Armağan; Kocabaş, Sibel; Bilgiçli, Ahmet T. [Department of Chemistry, Sakarya University, 54140 Esentepe, Sakarya (Turkey); Güney, Sevgi [Department of Chemistry, Istanbul Technical University, 34469 Maslak, Istanbul (Turkey); Kandaz, Mehmet, E-mail: mkandaz@sakarya.edu.tr [Department of Chemistry, Sakarya University, 54140 Esentepe, Sakarya (Turkey)

    2016-08-15

    We have presented in this paper, the synthesis, characterization, photophysical properties and electrochemical characterization of water soluble phthalocyanines (Pcs) bearing 8-hydroxyquinoline-5-sulfonicacid conjugates and their cationic quaternized counterpart that play important roles their application in photodynamic therapy (PDT). The periphery and non-periphery substituted phthalocyanines show high solubility and low aggregation tendency due to bulky 8-hydroxyquinoline-5-sulfonicacid steric hindrance moieties and axially bound counter chlorine anion. Singlet oxygen quantum yields, photodegradation quantum yields, photophysical properties and also the nature of the substituent and solvent effect on the photophysical and photochemical parameters of α-ZnPc and β-ZnPc are reported. In electrovalent cobalt (II) and manganese (III) compounds, metal based electron transfer reactions have been observed in addition to the common phthalocyanine ring-based electron transfer processes. The effect of point of substitution on the electrochemical properties of newly synthesized phthalocyanines substituted with 8-hydroxyquinoline-5-sulfonicacid group were evaluated.

  12. Direct on-chip DNA synthesis using electrochemically modified gold electrodes as solid support

    Science.gov (United States)

    Levrie, Karen; Jans, Karolien; Schepers, Guy; Vos, Rita; Van Dorpe, Pol; Lagae, Liesbet; Van Hoof, Chris; Van Aerschot, Arthur; Stakenborg, Tim

    2018-04-01

    DNA microarrays have propelled important advancements in the field of genomic research by enabling the monitoring of thousands of genes in parallel. The throughput can be increased even further by scaling down the microarray feature size. In this respect, microelectronics-based DNA arrays are promising as they can leverage semiconductor processing techniques with lithographic resolutions. We propose a method that enables the use of metal electrodes for de novo DNA synthesis without the need for an insulating support. By electrochemically functionalizing gold electrodes, these electrodes can act as solid support for phosphoramidite-based synthesis. The proposed method relies on the electrochemical reduction of diazonium salts, enabling site-specific incorporation of hydroxyl groups onto the metal electrodes. An automated DNA synthesizer was used to couple phosphoramidite moieties directly onto the OH-modified electrodes to obtain the desired oligonucleotide sequence. Characterization was done via cyclic voltammetry and fluorescence microscopy. Our results present a valuable proof-of-concept for the integration of solid-phase DNA synthesis with microelectronics.

  13. Optimization on electrochemical synthesis of HKUST-1 as candidate catalytic material for Green diesel production

    Science.gov (United States)

    Lestari, W. W.; Nugraha, R. E.; Winarni, I. D.; Adreane, M.; Rahmawati, F.

    2016-04-01

    In the effort to support the discovery of new renewable energy sources in Indonesia, biofuel is one of promising options. The conversion of vegetable oil into ready-biofuel, especially green diesel, needs several steps, one of which is a hydrogenation or hydro-deoxygenation reaction. In this case, the catalyst plays a very important role regarding to its activity and selectivity, and Metal-Organic Frameworks (MOFs) becoming a new generation of heterogeneous catalyst in this area. In this research, a preliminary study to optimize electrochemical synthesis of the catalytic material based on MOFs, namely HKUST-1 [Cu3(BTC)2], has been conducted. Some electrochemical reaction parameters were tested, for example by modifying the electrochemical synthetic conditions, i.e. by performing variation of voltages (12, 13, 14, and 15 Volt), temperatures (RT, 40, 60, and 80 °C) and solvents (ethanol, water, methanol and dimethyl-formamide (DMF)). Material characterization was carried out by XRD, SEM, FTIR, DTA/TG and SAA. The results showed that the optimum synthetic conditions of HKUST-1 are performed at room temperature in a solvent combination of water: ethanol (1: 1) and a voltage of 15 Volt for 2 hours. The XRD-analysis revealed that the resulted peaks are identical to the simulated powder pattern generated from single crystal data and comparable to the peaks of solvothermal method. However, the porosity of the resulting material through electrochemical method is still in the range of micro-pore according to IUPAC and 50% smaller than the porosity resulted from solvothermal synthesis. The corresponding compounds are thermally stable until 300 °C according to TG/DTA.

  14. Synthesis of Pt nanoparticles on electrochemically reduced graphene oxide by potentiostatic and alternate current methods

    Energy Technology Data Exchange (ETDEWEB)

    Molina, J.; Fernández, J.; Río, A.I. del; Bonastre, J.; Cases, F., E-mail: fjcases@txp.upv.es

    2014-03-01

    Reduced graphene oxide (RGO) has been synthesized on Pt wires by means of a potentiodynamic method between + 0.6 V and − 1.4 V for 20 scans. Cyclic voltammetry characterization of the coatings showed the typical capacitative behavior of graphene. Pt nanoparticles were synthesized on Pt–RGO electrodes by means of potentiostatic methods and a comparison between different synthesis potentials (− 0.16, 0, + 0.2 and + 0.4 V) for the same synthesis charge (mC·cm{sup −2}) was established. The electrodes obtained were characterized in 0.5 M H{sub 2}SO{sub 4} solution to observe the characteristic oxidation and reduction processes of the Pt surface. A 0.5 M H{sub 2}SO{sub 4}/0.5 M CH{sub 3}OH solution was used to measure the catalytic properties of the deposits against methanol oxidation. The most appropriate potential to perform the synthesis was 0 V followed by − 0.16 V and + 0.2 V. The morphology of the coatings varied depending on the potential applied as observed by scanning electron microscopy. Alternate current methods were also used to synthesize Pt nanoparticles and compare the results with the traditional potentiostatic method. Different frequencies were used: 0.1, 1, 10, 100, 1000 and 10 000 Hz. Alternate current synthesis is more efficient than traditional potentiostatic methods, obtaining more electroactive coatings with less effective synthesis time. - Highlights: • Reduced graphene oxide has been obtained by electrochemical reduction on Pt wires. • Pt nanoparticles have been obtained potentiostatically at different potentials. • Pt nanoparticles have been obtained by ac methods with different frequencies. • ac synthesis is a better synthesis method than potentiostatic synthesis.

  15. Synthesis of Pt nanoparticles on electrochemically reduced graphene oxide by potentiostatic and alternate current methods

    International Nuclear Information System (INIS)

    Molina, J.; Fernández, J.; Río, A.I. del; Bonastre, J.; Cases, F.

    2014-01-01

    Reduced graphene oxide (RGO) has been synthesized on Pt wires by means of a potentiodynamic method between + 0.6 V and − 1.4 V for 20 scans. Cyclic voltammetry characterization of the coatings showed the typical capacitative behavior of graphene. Pt nanoparticles were synthesized on Pt–RGO electrodes by means of potentiostatic methods and a comparison between different synthesis potentials (− 0.16, 0, + 0.2 and + 0.4 V) for the same synthesis charge (mC·cm −2 ) was established. The electrodes obtained were characterized in 0.5 M H 2 SO 4 solution to observe the characteristic oxidation and reduction processes of the Pt surface. A 0.5 M H 2 SO 4 /0.5 M CH 3 OH solution was used to measure the catalytic properties of the deposits against methanol oxidation. The most appropriate potential to perform the synthesis was 0 V followed by − 0.16 V and + 0.2 V. The morphology of the coatings varied depending on the potential applied as observed by scanning electron microscopy. Alternate current methods were also used to synthesize Pt nanoparticles and compare the results with the traditional potentiostatic method. Different frequencies were used: 0.1, 1, 10, 100, 1000 and 10 000 Hz. Alternate current synthesis is more efficient than traditional potentiostatic methods, obtaining more electroactive coatings with less effective synthesis time. - Highlights: • Reduced graphene oxide has been obtained by electrochemical reduction on Pt wires. • Pt nanoparticles have been obtained potentiostatically at different potentials. • Pt nanoparticles have been obtained by ac methods with different frequencies. • ac synthesis is a better synthesis method than potentiostatic synthesis

  16. Electrochemical Study of Bromide in the Presence of 1,3-Indandione. Application to the Electrochemical Synthesis of Bromo Derivatives of 1,3-Indandione

    Directory of Open Access Journals (Sweden)

    N. Akaberi

    2001-06-01

    Full Text Available The electrochemical oxidation of bromide in the presence of 1,3-indandione (1 in water/acetic acid and methanol/acetic acid mixtures has been studied by cyclic voltammetry and controlled-potential coulometry. The results indicate the participation of 1,3-indandione in the bromination reaction. On the basis of the electroanalytical and preparative results a reaction mechanism including electron transfer, chemical reaction and regeneration of bromide was discussed. The electrochemical synthesis of bromo derivatives of 1,3-indandione (2-3 has been successfully performed at constant current, in an undivided cell, in good yield and purity.

  17. Room-temperature Electrochemical Synthesis of Carbide-derived Carbons and Related Materials

    Energy Technology Data Exchange (ETDEWEB)

    Gogotsi, Yury [Drexel Univ., Philadelphia, PA (United States). Nanomaterials Group. Materials Science and Engineering Dept.

    2015-02-28

    This project addresses room-temperature electrochemical etching as an energy-efficient route to synthesis of 3D nanoporous carbon networks and layered 2D carbons and related structures, as well as provides fundamental understanding of structure and properties of materials produced by this method. Carbide-derived-carbons (CDCs) are a growing class of nanostructured carbon materials with properties that are desirable for many applications, such as electrical energy and gas storage. The structure of these functional materials is tunable by the choice of the starting carbide precursor, synthesis method, and process parameters. Moving from high-temperature synthesis of CDCs through vacuum decomposition above 1400°C and chlorination above 400°C, our studies under the previous DOE BES support led to identification of precursor materials and processing conditions for CDC synthesis at temperatures as low as 200°C, resulting in amorphous and highly reactive porous carbons. We also investigated synthesis of monolithic CDC films from carbide films at 250-1200°C. The results of our early studies provided new insights into CDC formation, led to development of materials for capacitive energy storage, and enabled fundamental understanding of the electrolyte ions confinement in nanoporous carbons.

  18. Electrochemical Synthesis of a Microporous Conductive Polymer Based on a Metal-Organic Framework Thin Film

    KAUST Repository

    Lu, Chunjing

    2014-05-22

    A new approach to preparing 3D microporous conductive polymer has been demonstrated in the electrochemical synthesis of a porous polyaniline network with the utilization of a MOF thin film supported on a conducting substrate. The prepared porous polyaniline with well-defined uniform micropores of 0.84 nm exhibits a high BET surface area of 986 m2 g−1 and a high electric conductivity of 0.125 S cm−1 when doped with I2, which is superior to existing porous conducting materials of porous MOFs, CMPs, and COFs.

  19. An electrochemical procedure coupled with a Schiff base method; application to electroorganic synthesis of new nitrogen-containing heterocycles

    International Nuclear Information System (INIS)

    Dowlati, Bahram; Othman, Mohamed Rozali

    2013-01-01

    The synthesis of Nitrogen-containing heterocycles has been achieved using chemical and electrochemical methods, respectively. The direct chemical synthesis of nucleophiles proceeds through the Schiff base chemical reaction. This procedure offers an alternate reaction between dicarbonyl compounds and diamines leads to the formation of products. The results indicate that the Schiff base chemical method for synthesis of the product has successfully performed in excellent overall yield. In the electrochemical step, a series of Nitrogen-containing compounds were electrosynthesized. Various parameters such as the applied potential, pH of the electrolytic solution, cell configuration and also purification techniques, were carried out to optimize the yields of corresponding products. New Nitrogen-containing heterocycle derivatives were synthesized using an electrochemical procedure coupled with a Schiff base as a facile, efficient and practical method. The products have been characterized after purification by IR, 1 H NMR, 13 C NMR and ESI-MS 2

  20. Electrodeposition synthesis and electrochemical properties of nanostructured γ-MnO 2 films

    Science.gov (United States)

    Chou, Shulei; Cheng, Fangyi; Chen, Jun

    The thin films of carambola-like γ-MnO 2 nanoflakes with about 20 nm in thickness and at least 200 nm in width were prepared on nickel sheets by combination of potentiostatic and cyclic voltammetric electrodeposition techniques. The as-prepared MnO 2 nanomaterials, which were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), were used as the active material of the positive electrode for primary alkaline Zn/MnO 2 batteries and electrochemical supercapacitors. Electrochemical measurements showed that the MnO 2 nanoflake films displayed high potential plateau (around 1.0 V versus Zn) in primary Zn/MnO 2 batteries at the discharge current density of 500 mA g -1 and high specific capacitance of 240 F g -1 at the current density of 1 mA cm -2. This indicated the potential application of carambola-like γ-MnO 2 nanoflakes in high-power batteries and electrochemical supercapacitors. The growth process for the one- and three-dimensional nanostructured MnO 2 was discussed on the basis of potentiostatic and cyclic voltammetric techniques. The present synthesis method can be extended to the preparation of other nanostructured metal-oxide films.

  1. Solvothermal synthesis of Li–Al layered double hydroxides and their electrochemical performance

    International Nuclear Information System (INIS)

    Wei, Jinbo; Gao, Zan; Song, Yanchao; Yang, Wanlu; Wang, Jun; Li, Zhanshuang; Mann, Tom; Zhang, Milin; Liu, Lianhe

    2013-01-01

    In this paper, for the first time, Li/Al layered double hydroxides (LDHs) were synthesized by a facile and environment-friendly solvothermal approach. X-ray diffraction patterns show that the as-prepared products belong to the hexagonal phase. Well-defined LDHs particles with spiral-shape (1–2 μm), hexagonal (2–3 μm) and petal-like structures (10–15 μm) have been successfully fabricated by adjusting the content of water/ethanol in the synthesis process. A possible growth mechanism was proposed for the formation of these structures. Their electrochemical performances were investigated by cyclic voltammetry, galvanostatic charge/discharge test and electrochemical impedance spectroscopy. The hexagonal Li/Al LDHs calcined at 450 °C exhibit the specific capacitance of 848 F g −1 at a current density of 1.25 A g −1 . The high specific capacitance and remarkable rate capacity of Li/Al LDHs are promising for applications in capacitors and low-cost aqueous lithium ion batteries. - Graphical abstract: Hexagonal Li/Al layered double hydroxides (LDHs) with high specific surface area and remarkable rate capacity via a facile and environmentally friendly solvothermal approach. Highlights: ► Li/Al LDHs with different morphologies were fabricated by a solvothermal method. ► Hexagonal Li/Al LDHs display better electrochemical performance. ► A possible growth mechanism to explain the different morphology is proposed

  2. Excellent electrochemical performances of cabbage-like polyaniline fabricated by template synthesis

    Science.gov (United States)

    Hu, Chenglong; Chen, Shaoyun; Wang, Yuan; Peng, Xianghong; Zhang, Weihong; Chen, Jian

    2016-07-01

    In this article, we explore a novel route to fabricate cabbage-like polyaniline (PANI) by in situ polymerization of aniline using the hydroxylated poly (methyl methacrylate) nanospheres (i.e. PMMAsbnd OHsbnd NS) as a template. A maximum specific capacitance of 584 F/g (the current density is 0.1 A/g) is achieved at 10 mV s-1 as well as a high stability of over 3000 cycles (the decrease in the SC is ∼9.1%), which suggests the potential application of the cabbage-like polyaniline in supercapacitors. The predominant electrochemical performances of the cabbage-like polyaniline can be attributed to their large surface area and larger-scale π-π conjugated system present in the quinoid structure of the PANI molecular chain, which can drastically facilitate electron diffusion and improve the utilization of the electroactive PANI during the charge/discharge processes. Accordingly, the facility of charge transfer can decrease resistance along with the PANI molecular chain to improve the electrochemical stability and achieve high-capacitance response characteristics. The present study introduces a new synthesis method for the development of various morphology of other conducting polymer, which may find potential applications in a variety of high-performance electrochemical devices.

  3. One pot synthesis of dandelion-like polyaniline coated gold nanoparticles composites for electrochemical sensing applications.

    Science.gov (United States)

    Lu, Zhiwei; Dai, Wanlin; Liu, Baichen; Mo, Guangquan; Zhang, Junjun; Ye, Jiaping; Ye, Jianshan

    2018-04-18

    In this work, we report a facile and green strategy for one pot and in-situ synthesis of a dandelion-like conductive polyaniline coated gold nanoparticle nanocomposites (Au@PANI). The Au@PANI was characterized by SEM, TEM, XRD, TGA, FTIR, UV-vis and conductivity measurement, respectively. Newly-designed Au@PANI materials possessed a significantly high conductivity and strong adsorption capability. Thus, the Au@PANI modified glassy carbon electrode (GCE) was utilized for construct a novel electrochemical sensor for the simultaneous assay of Pb 2+ and Cu 2+ using square wave anodic stripping voltammetry (SWASV). Under the optimized conditions, an excellent electrochemical response in the simultaneous of Pb 2+ and Cu 2+ with detection limit of 0.003 and 0.008 μM (S/N = 3), respectively. Moreover, the prepared sensors realized an excellent reproducibility, repeatability and long term stability, as well as reliable practical assays in real water samples. Besides, the possible formation mechanism and sensing mechanism of Au@PANI nanocomposites have been discussed in detail. We believe this study provides a novel method of fabrication of noble metal nanoparticles decorated conducting polymer materials for the electrochemical sensing applications. Copyright © 2018 Elsevier Inc. All rights reserved.

  4. Electrodeposition synthesis and electrochemical properties of nanostructured {gamma}-MnO{sub 2} films

    Energy Technology Data Exchange (ETDEWEB)

    Chou, Shulei; Cheng, Fangyi; Chen, Jun [Institute of New Energy Material Chemistry, Nankai University, Tianjin 300071 (China)

    2006-11-08

    The thin films of carambola-like {gamma}-MnO{sub 2} nanoflakes with about 20nm in thickness and at least 200nm in width were prepared on nickel sheets by combination of potentiostatic and cyclic voltammetric electrodeposition techniques. The as-prepared MnO{sub 2} nanomaterials, which were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), were used as the active material of the positive electrode for primary alkaline Zn/MnO{sub 2} batteries and electrochemical supercapacitors. Electrochemical measurements showed that the MnO{sub 2} nanoflake films displayed high potential plateau (around 1.0V versus Zn) in primary Zn/MnO{sub 2} batteries at the discharge current density of 500mAg{sup -1} and high specific capacitance of 240Fg{sup -1} at the current density of 1mAcm{sup -2}. This indicated the potential application of carambola-like {gamma}-MnO{sub 2} nanoflakes in high-power batteries and electrochemical supercapacitors. The growth process for the one- and three-dimensional nanostructured MnO{sub 2} was discussed on the basis of potentiostatic and cyclic voltammetric techniques. The present synthesis method can be extended to the preparation of other nanostructured metal-oxide films. (author)

  5. A Simple Synthesis of Two-Dimensional Ultrathin Nickel Cobaltite Nanosheets for Electrochemical Lithium Storage

    International Nuclear Information System (INIS)

    Zhu, Youqi; Cao, Chuanbao

    2015-01-01

    We report a simple microwave-assisted method to fabricate high-quality two-dimensional (2D) ultrathin NiCo 2 O 4 nanosheets with a geometrically graphene-like architecture. The unique large-area nanostructures represent an ultrahigh surface atomic ratio with almost all active elements exposed outside for surface-dependent electrochemical reaction processes. Experimental results reveal that the as-synthesized ultrathin NiCo 2 O 4 nanosheets show excellent electrochemical performances for lithium storage application. The ultrathin NiCo 2 O 4 nanosheets could deliver a high first discharge capacity (1287.1 mAh g −1 ) with initial Coulombic efficiency of 80.0% at 200 mA g −1 current density. The reversible lithium storage capacity still retains at 804.8 mAh g −1 in the 100th cycle, suggesting a good cycling stability. The excellent electrochemical properties of the as-synthesized NiCo 2 O 4 nanosheets could be ascribed to the unique ultrathin 2D architecture, which could offer large exposed active surface with more lithium-insertion channels and significantly reduce lithium ion diffusion distance. The cost-efficient synthesis and excellent lithium storage properties make the 2D NiCo 2 O 4 nanosheets as a promising anode material for high-performance lithium ion batteries

  6. Bio-electrochemical synthesis of commodity chemicals by autotrophic acetogens utilizing CO2 for environmental remediation.

    Science.gov (United States)

    Jabeen, Gugan; Farooq, Robina

    2016-09-01

    Bio-electrochemical synthesis (BES) is a technique in which electro-autotrophic bacteria such as Clostridium ljungdahlii utilize electric currents as an electron source from the cathode to reduce CO2 to extracellular, multicarbon, exquisite products through autotrophic conversion. The BES of volatile fatty acids and alcohols directly from CO2 is a sustainable alternative for non-renewable, petroleum-based polymer production. This conversion of CO2 implies reduction of greenhouse gas emissions. The synthesis of heptanoic acid, heptanol, hexanoic acid and hexanol, for the first time, by Clostridium ljungdahlii was a remarkable achievement of BES. In our study, these microorganisms were cultivated on the cathode of a bio-electrochemical cell at -400 mV by a DC power supply at 37 degree Centrigrade, pH 6.8, and was studied for both batch and continuous systems. Pre-enrichment of bio-cathode enhanced the electroactivity of cells and resulted in maximizing extracellular products in less time. The main aim of the research was to investigate the impact of low-cost substrate CO2, and the longer cathode recovery range was due to bacterial reduction of CO2 to multicarbon chemical commodities with electrons driven from the cathode. Reactor design was simplified for cost-effectiveness and to enhance energy efficiencies. The Columbic recovery of ethanoic acid, ethanol, ethyl butyrate, hexanoic acid, heptanoic acid and hexanol being in excess of 80 percent proved that BES was a remarkable technology.

  7. Electrochemically shape-controlled synthesis in deep eutectic solvents of Pt nanoflowers with enhanced activity for ethanol oxidation

    International Nuclear Information System (INIS)

    Wei Lu; Fan Youjun; Wang Honghui; Tian Na; Zhou Zhiyou; Sun Shigang

    2012-01-01

    Highlights: ► The electrochemically shape-controlled synthesis in deep eutectic solvents (DESs) has been applied to produce the uniform Pt nanoflowers with sharp single crystal petals and high density of atomic steps. ► The as-prepared Pt nanoflowers exhibit higher electrocatalytic activity and stability than commercial Pt black catalyst toward ethanol electrooxidation. ► The growth of Pt nanoflowers in DESs by the simple electrochemical route is straightforward and controllable in terms of nanoflowers’ shape and size. - Abstract: The electrochemically shape-controlled synthesis in deep eutectic solvents (DESs) has been applied to produce the electrocatalyst of Pt nanoflowers. The uniform Pt nanoflowers with sharp single crystal petals and high density of atomic steps were characterized by SEM, TEM, XRD, XPS and electrochemical tests. The results illustrated that the as-prepared Pt nanoflowers exhibit higher electrocatalytic activity and stability than commercial Pt black catalyst toward ethanol electrooxidation. The growth of Pt nanoflowers in DESs by the simple electrochemical route is straightforward and controllable in terms of nanoflowers’ shape and size, which can be applied in shape-controlled synthesis of other noble metal nanoparticles with high catalytic activity.

  8. One pot electrochemical synthesis of polymer/CNT/metal nanoparticles for fuel cell applications

    Science.gov (United States)

    Ventrapragada, Lakshman; Zhu, Jingyi; Karakaya, Mehmet; Podila, Ramakrishna; Rao, Apparao; Clemson Nanomaterials center Team

    Carbon nanotubes (CNTs) have become a key player in the design of materials for energy applications. They gained their popularity in industrial and scientific research due to their unique properties like excellent conductivity, high surface area, etc. Here we used chemical vapor deposition (CVD) to synthesize two types of CNTs namely, helically coiled CNTs and vertically aligned CNTs. These CNTs were subsequently used to make composites with conducting polymers and metal nanoparticles. One pot electrochemical synthesis was designed to electropolymerize aniline, pyrrole etc. on the surface of the electrode with simultaneous deposition of platinum and gold metal nanoparticles, and CNTs in the polymer matrix. The as synthesized composite materials were characterized with scanning electron microscope for surface morphology and spectroscopic techniques like Raman, UV-Vis for functionality. These were used to study electrocatalytic oxidation of methanol and ethanol for alkaline fuel cell applications. Electrodes fabricated from these composites not only showed good kinetics but also exhibited excellent stability. Uniqueness of this composite lies in its simple two step synthesis and it doesn't involve any surfactants unlike conventional chemical synthesis routes.

  9. Electrochemical synthesis of gold nanorods in track-etched polycarbonate membrane using removable mercury cathode

    International Nuclear Information System (INIS)

    Sharma, Manoj K.; Ambolikar, Arvind S.; Aggarwal, Suresh K.

    2012-01-01

    The electrochemical template synthesis of gold nanorods within the cylindrical pores of track-etched polycarbonate (PC) membrane using a removable mercury cathode is reported. The novelty of this new approach is that it eliminates the requirement of coating an approximately 500 nm–1 μm-thick metallic layer, as conducting substrate, onto one surface of the insulating template membrane by the sputter deposition technique. A two-compartment electrochemical cell was designed and used for this work. The PC membrane was placed between the two compartments separating the aqueous solution of HAuCl 4 from mercury. Mercury, filled in one of the compartments, is in contact with one surface of the membrane (similar to sputter-deposited metallic layer) and serves as the conducting substrate/cathode for the electrochemical deposition of gold in the nanopores of track-etched PC membrane. Once the electrodeposition is completed, the mercury and the HAuCl 4 solution are removed from the compartments, and a malleable track-etched PC membrane embedded with free-standing gold nanorods is obtained. The ensemble of the metal nanorods grown in the template membrane is not attached to any conducting substrate, and gold nanorods can be freed from the template membrane after the dissolution. The Au-deposited PC membrane and free-standing Au nanorods were characterized by EDXRF, XRD, UV–Visible spectroscopy, AFM, and FEG-TEM. The EDXRF and XRD studies confirmed the deposition of the face-centered cubic phase of Au in the pores of the PC membrane. The TEM studies showed the formation of a cigar-shaped gold nanorod in the cylindrical pores of the PC membrane. The diameter of gold nanorods ranges from 100 to 200 nm. The new approach is simple, cost-effective, and saves time.

  10. Rapid synthesis of Co, Ni co-doped ZnO nanoparticles: Optical and electrochemical properties

    Energy Technology Data Exchange (ETDEWEB)

    Romeiro, Fernanda C.; Marinho, Juliane Z.; Lemos, Samantha C.S. [Instituto de Química, Universidade Federal de Uberlândia, 38400-902 Uberlândia, MG (Brazil); Moura, Ana P. de [LIEC, Instituto de Química, Universidade Estadual Paulista, 14800-900 Araraquara, SP (Brazil); Freire, Poliana G. [Instituto de Química, Universidade Federal de Uberlândia, 38400-902 Uberlândia, MG (Brazil); Silva, Luis F. da; Longo, Elson [LIEC, Instituto de Química, Universidade Estadual Paulista, 14800-900 Araraquara, SP (Brazil); Munoz, Rodrigo A.A. [Instituto de Química, Universidade Federal de Uberlândia, 38400-902 Uberlândia, MG (Brazil); Lima, Renata C., E-mail: rclima@iqufu.ufu.br [Instituto de Química, Universidade Federal de Uberlândia, 38400-902 Uberlândia, MG (Brazil)

    2015-10-15

    We report for the first time a rapid preparation of Zn{sub 1−2x}Co{sub x}Ni{sub x}O nanoparticles via a versatile and environmentally friendly route, microwave-assisted hydrothermal (MAH) method. The Co, Ni co-doped ZnO nanoparticles present an effect on photoluminescence and electrochemical properties, exhibiting excellent electrocatalytic performance compared to undoped ZnO sample. Photoluminescence spectroscopy measurements indicated the reduction of the green–orange–red visible emission region after adding Co and Ni ions, revealing the formation of alternative pathways for the generated recombination. The presence of these metallic ions into ZnO creates different defects, contributing to a local structural disorder, as revealed by Raman spectra. Electrochemical experiments revealed that the electrocatalytic oxidation of dopamine on ZnO attached to multi-walled carbon nanotubes improved significantly in the Co, Ni co-doped ZnO samples when compared to pure ZnO. - Graphical abstract: Rapid synthesis of Co, Ni co-doped ZnO nanoparticles: optical and electrochemical properties. Co, Ni co-doped ZnO hexagonal nanoparticles with optical and electrocatalytic properties were successfully prepared for the first time using a microwave hydrothermal method at mild conditions. - Highlights: • Co{sup 2+} and Ni{sup 2+} into ZnO lattice obtained a mild and environmentally friendly process. • The heating method strongly influences in the growth and shape of the particles. • Short-range defects generated by the ions insertion affects the photoluminescence. • Doped ZnO nanoparticles improve the electrocatalytic properties of pure oxide.

  11. Synthesis and electrochemical properties of {alpha}-MnO{sub 2} microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Wang Hongen [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Zhengzhou Research Institute of CHALCO, Zhengzhou Research Institute of Light Metals, Zhengzhou 450041 (China); Qian Dong [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China)], E-mail: qiandong6@yahoo.com.cn

    2008-06-15

    We report the synthesis of {alpha}-MnO{sub 2} microspheres by a low-temperature hydrothermal method involving no templates or catalysts. The products were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy-dispersive X-ray spectrum (EDX), transmission electron microscopy (TEM), Fourier transform infrared spectrum (FT-IR), and Brunauer-Emmett-Teller (BET). The results show that the as-synthesized products are mainly composed of large quantities of {alpha}-MnO{sub 2} microspheres having a sea-urchin shape and a few microspheres constructed of small nanorods. Electrochemical characterization indicates that the resulting {alpha}-MnO{sub 2} microspheres display promising discharge properties than the commercial electrolytic manganese dioxides (EMD) when used as cathodes in alkaline Zn-MnO{sub 2} batteries.

  12. Electrochemical synthesis of poly(aniline-co-fluoroaniline) films and their application as humidity sensing material

    International Nuclear Information System (INIS)

    Sharma, Amit L.

    2009-01-01

    In the present manuscript, humidity sensing properties of a copolymer, poly(aniline-co-fluoroaniline) have been reported. The copolymer was prepared on indium-tin-oxide coated glass plates as well as platinum surface in the form of films using electrochemical technique (versus standard calomel electrode) in acidic medium. Synthesis of copolymer films was supported by Fourier transform infra-red, ultraviolet-visible, scanning electron microscope and cyclic voltammetry techniques. Molecular weight and electrical conductivity of these films were measured at different temperature. Polyaniline and poly(2-fluoroaniline) films were also synthesized using the same technique to compare the data with copolymer film. On exposure to humid atmosphere, the response behaviour of copolymer film exhibited a change in resistance with respect to relative humidity (RH). This copolymer film was found to be most sensitive in the 30-65% RH range and shows a linear behaviour with in this range.

  13. Fused 1,2,3-Dithiazoles: Convenient Synthesis, Structural Characterization, and Electrochemical Properties

    Directory of Open Access Journals (Sweden)

    Lidia S. Konstantinova

    2016-05-01

    Full Text Available A new general protocol for synthesis of fused 1,2,3-dithiazoles by the reaction of cyclic oximes with S2Cl2 and pyridine in acetonitrile has been developed. The target 1,2,3-dithiazoles fused with various carbocycles, such as indene, naphthalenone, cyclohexadienone, cyclopentadiene, and benzoannulene, were selectively obtained in low to high yields. In most cases, the hetero ring-closure was accompanied by chlorination of the carbocyclic moieties. With naphthalenone derivatives, a novel dithiazole rearrangement (15→13 featuring unexpected movement of the dithiazole ring from α- to β-position, with respect to keto group, was discovered. Molecular structure of 4-chloro-5H-naphtho[1,2-d][1,2,3]dithiazol-5-one 13 was confirmed by single-crystal X-ray diffraction. Electrochemical properties of 13 were studied by cyclic voltammetry and a complex behavior was observed, most likely including hydrodechlorination at a low potential.

  14. In situ chemical synthesis of ruthenium oxide/reduced graphene oxide nanocomposites for electrochemical capacitor applications.

    Science.gov (United States)

    Kim, Ji-Young; Kim, Kwang-Heon; Yoon, Seung-Beom; Kim, Hyun-Kyung; Park, Sang-Hoon; Kim, Kwang-Bum

    2013-08-07

    An in situ chemical synthesis approach has been developed to prepare ruthenium oxide/reduced graphene oxide (RGO) nanocomposites. It is found that as the C/O ratio increases, the number density of RuO2 nanoparticles decreases, because the chemical interaction between the Ru ions and the oxygen-containing functional groups provides anchoring sites where the nucleation of particles takes place. For electrochemical capacitor applications, the microwave-hydrothermal process was carried out to improve the conductivity of RGO in RuO2/RGO nanocomposites. The significant improvement in capacitance and high rate capability might result from the RuO2 nanoparticles used as spacers that make the interior layers of the reduced graphene oxide electrode available for electrolyte access.

  15. Electrochemical synthesis of self-organized TiO2 crystalline nanotubes without annealing

    Science.gov (United States)

    Giorgi, Leonardo; Dikonimos, Theodoros; Giorgi, Rossella; Buonocore, Francesco; Faggio, Giuliana; Messina, Giacomo; Lisi, Nicola

    2018-03-01

    This work demonstrates that upon anodic polarization in an aqueous fluoride-containing electrolyte, TiO2 nanotube array films can be formed with a well-defined crystalline phase, rather than an amorphous one. The crystalline phase was obtained avoiding any high temperature annealing. We studied the formation of nanotubes in an HF/H2O medium and the development of crystalline grains on the nanotube wall, and we found a facile way to achieve crystalline TiO2 nanotube arrays through a one-step anodization. The crystallinity of the film was influenced by the synthesis parameters, and the optimization of the electrolyte composition and anodization conditions (applied voltage and time) were carried out. For comparison purposes, crystalline anatase TiO2 nanotubes were also prepared by thermal treatment of amorphous nanotubes grown in an organic bath (ethylene glycol/NH4F/H2O). The morphology and the crystallinity of the nanotubes were studied by field emission gun-scanning electron microscopy (FEG-SEM) and Raman spectroscopy, whereas the electrochemical and semiconducting properties were analyzed by means of linear sweep voltammetry, impedance spectroscopy, and Mott-Schottky plots. X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) allowed us to determine the surface composition and the electronic structure of the samples and to correlate them with the electrochemical data. The optimal conditions to achieve a crystalline phase with high donor concentration are defined.

  16. Characterization and optimization of cathodic conditions for H2O2 synthesis in microbial electrochemical cells.

    Science.gov (United States)

    Sim, Junyoung; An, Junyeong; Elbeshbishy, Elsayed; Ryu, Hodon; Lee, Hyung-Sool

    2015-11-01

    Cathode potential and O2 supply methods were investigated to improve H2O2 synthesis in an electrochemical cell, and optimal cathode conditions were applied for microbial electrochemical cells (MECs). Using aqueous O2 for the cathode significantly improved current density, but H2O2 conversion efficiency was negligible at 0.3-12%. Current density decreased for passive O2 diffusion to the cathode, but H2O2 conversion efficiency increased by 65%. An MEC equipped with a gas diffusion cathode was operated with acetate medium and domestic wastewater, which presented relatively high H2O2 conversion efficiency from 36% to 47%, although cathode overpotential was fluctuated. Due to different current densities, the maximum H2O2 production rate was 141 mg H2O2/L-h in the MEC fed with acetate medium, but it became low at 6 mg H2O2/L-h in the MEC fed with the wastewater. Our study clearly indicates that improving anodic current density and mitigating membrane fouling would be key parameters for large-scale H2O2-MECs. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Synthesis and Electrochemical Study of a TCAA Derivative – A potential bipolar redox-active material

    International Nuclear Information System (INIS)

    Hagemann, Tino; Winsberg, Jan; Wild, Andreas; Schubert, Ulrich S.

    2017-01-01

    The 2,3,7,8-tetracyano-1,4,5,6,9,10-hexazaanthracene (TCAA) derivatives represent an interesting substance class for future research on organic electronic devices, such as solar cells, organic batteries or redox-flow batteries (RFBs). Because of their multivalent redox behavior they are potentially “bipolar”, usable both as cathode and anode activ charge-storage materials. Furthermore, they show a strong absorption and fluorescence behavior both in solution and solid state, rendering them a promising emitter for electroluminescence devices, like lamps or displays. In order to evaluate a TCAA for electrochemical applications the derivative 2,3,7,8-tetracyano-5,10-diphenyl-5,10-dihydrodipyrazino[2,3-b:2′,3′-e] pyrazine (2) was synthesized in two straightforward synthesis steps. The electrochemical behavior of 2 was initially determined by density functional theory (DFT) calculation and afterwards investigated via rotating disc electrode (RDE), UV–vis–NIR spectroelectrochemical as well as cyclic voltammetry (CV) measurements. It features a quasi-reversible oxidation and re-reduction at E ½ = 1.42 V vs. Fc + /Fc with a peak split of 96 mV and a quasi-reversible reduction and re-oxidation at E ½ = −1.49 V vs. Fc + /Fc with a peak split of 174 mV, which lead to a theoretical potential difference of 2.91 V.

  18. Hydrothermal synthesis of mesoporous metal oxide arrays with enhanced properties for electrochemical energy storage

    International Nuclear Information System (INIS)

    Xiao, Anguo; Zhou, Shibiao; Zuo, Chenggang; Zhuan, Yongbing; Ding, Xiang

    2015-01-01

    Highlights: • NiO mesoporous nanowall arrays are prepared via hydrothermal method. • Mesoporous nanowall arrays are favorable for fast ion/electron transfer. • NiO mesoporous nanowall arrays show good supercapacitor performance. - Abstract: Mesoporous nanowall NiO arrays are prepared by a facile hydrothermal synthesis method with a following annealing process. The NiO nanowall shows continuous mesopores ranging from 5 to 10 nm and grows vertically on the substrate forming a porous net-like structure with macropores of 20–300 nm. A plausible mechanism is proposed for the growth of mesoporous nanowall NiO arrays. As cathode material of pseudocapacitors, the as-prepared mesoporous nanowall NiO arrays show good pseudocapacitive performances with a high capacitance of 600 F g −1 at 2 A g −1 and impressive high-rate capability with a specific capacitance of 338 F g −1 at 40 A g −1 . In addition, the mesoporous nanowall NiO arrays possess good cycling stability. After 6000 cycles at 2 A g −1 , a high capacitance of 660 F g −1 is attained, and no obvious degradation is observed. The good electrochemical performance is attributed to its highly porous morphology, which provides large reaction surface and short ion diffusion paths, leading to enhanced electrochemical properties

  19. Synthesis, characterisation and electrochemical evaluation of reduced graphene oxide modified antimony nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Silwana, Bongiwe; Horst, Charlton van der [Natural Resources and the Environment (NRE), Council for Scientific and Industrial Research (CSIR), Stellenbosch 7600 (South Africa); SensorLab, Department of Chemistry, University of the Western Cape, Bellville 7535 (South Africa); Iwuoha, Emmanuel [SensorLab, Department of Chemistry, University of the Western Cape, Bellville 7535 (South Africa); Somerset, Vernon, E-mail: vsomerset@csir.co.za [Natural Resources and the Environment (NRE), Council for Scientific and Industrial Research (CSIR), Stellenbosch 7600 (South Africa)

    2015-10-01

    This paper demonstrates some aspects on the synthesis and characterisation of nanoparticles of metallic alloys using polyvinyl alcohol as a stabiliser, which combines high surface area and superior hybrid properties. The present experimental design was to synthesise a nanocomposite of reduced graphene oxide and antimony nanoparticles to be used as thin films for macro- and micro-carbon electrodes for enhancing sensing of different toxic metal pollutants in the environment. The synthetic process of reduced graphene oxide was done using the modified Hummers method while antimony pentachloride was reduced with sodium borohydride into nanoparticles of antimony using polyvinyl-alcohol as a stabiliser. The systematic investigation of morphology was done by scanning electron microscopy and high resolution-transmission electron microscope, which revealed the synthesis of a product, consists of reduced graphene oxide antimony nanoparticles. The electrochemical behaviour of the reduced graphene oxide antimony nanoparticles coated on a glassy carbon electrode was performed using voltammetric and impedance techniques. Electrochemical impedance measurements showed that the overall resistance, including the charge–transfer resistance, was smaller with reduced graphene oxide antimony nanoparticles than reduced graphene oxide and antimony nanoparticles, on their own. Evaluation of the reduced graphene oxide antimony nanoparticle sensor in the stripping voltammetry has shown a linear working range for concentration of platinum (II) between 6.0 × 10{sup −6}–5.4 × 10{sup −5} μg L{sup −1} with limit of detection of 6 × 10{sup −6} μg L{sup −1} (signal-to-noise ratio = 3), which is below the World Health Organisation guidelines for freshwater. - Highlights: • Reduced graphene oxide modified antimony nanoparticles were chemically synthesised. • TEM results show rGO-Sb nanoparticles with a diameter range of between 2 and 20 nm. • Impedance results confirm

  20. Synthesis of microsphere silicon carbide/nanoneedle manganese oxide composites and their electrochemical properties as supercapacitors

    Science.gov (United States)

    Kim, Myeongjin; Yoo, Youngjae; Kim, Jooheon

    2014-11-01

    Synthesis of microsphere silicon carbide/nanoneedle MnO2 (SiC/N-MnO2) composites for use as high-performance materials in supercapacitors is reported herein. The synthesis procedure involves the initial treatment of silicon carbide (SiC) with hydrogen peroxide to obtain oxygen-containing functional groups to provide anchoring sites for connection of SiC and the MnO2 nanoneedles (N-MnO2). MnO2 nanoneedles are subsequently formed on the SiC surface. The morphology and microstructure of the as-prepared composites are characterized via X-ray diffractometry, field-emission scanning electron microscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy. The characterizations indicate that MnO2 nanoneedles are homogeneously formed on the SiC surface in the composite. The capacitive properties of the as-prepared SiC/N-MnO2 electrodes are evaluated using cyclic voltammetry, galvanostatic charge/discharge testing, and electrochemical impedance spectroscopy in a three-electrode experimental setup using a 1-M Na2SO4 aqueous solution as the electrolyte. The SiC/N-MnO2(5) electrode, for which the MnO2/SiC feed ratio is 5:1, displays a specific capacitance as high as 273.2 F g-1 at 10 mV s-1.

  1. Electrochemical Processes

    DEFF Research Database (Denmark)

    Bech-Nielsen, Gregers

    1997-01-01

    The notes describe in detail primary and secondary galvanic cells, fuel cells, electrochemical synthesis and electroplating processes, corrosion: measurments, inhibitors, cathodic and anodic protection, details of metal dissolution reactions, Pourbaix diagrams and purification of waste water from...

  2. The Effects of Voltage and Concentration of Sodium Bicarbonate on Electrochemical Synthesis of Ethanol from Carbon Dioxide Using Brass as Cathode

    Science.gov (United States)

    Ramadan, Septian; Fariduddin, Sholah; Rizki Aminudin, Afianti; Kurnia Hayatri, Antisa; Riyanto

    2017-11-01

    The effects of voltage and concentration of sodium bicarbonate were investigated to determine the optimum conditions of the electrochemical synthesis process to convert carbon dioxide into ethanol. The conversion process is carried out using a sodium bicarbonate electrolyte solution in an electrochemical synthesis reactor equipped with a cathode and anode. As the cathode was used brass, while as the anode carbon was utilized. Sample of the electrochemical synthesis process was analyzed by gas chromatography to determine the content of the compounds produced. The optimum electrochemical synthesis conditions to convert carbon dioxide into ethanol are voltage and concentration of sodium bicarbonate are 3 volts and 0.4 M with ethanol concentration of 1.33%.

  3. Chemical and Electrochemical Synthesis of Polypyrrole Using Carrageenan as a Dopant: Polypyrrole/Multi-Walled Carbon Nanotube Nanocomposites

    Directory of Open Access Journals (Sweden)

    Mostafizur Rahaman

    2018-06-01

    Full Text Available In this article, iota-carrageenan (IC and kappa-carrageenan (KC are used as dopants for the chemical and electrochemical synthesis of polypyrrole (PPy. The composites of chemically synthesized PPy with multi-walled carbon nanotubes (MWNTs were prepared using an in situ technique. Both the dialyzed and non-dialyzed IC and KC were used as dopants for electrochemical polymerization of pyrrole. Chemically synthesized PPy and PPy/MWNTs composites were studied by ultraviolet visible (UV-vis absorption spectra to investigate the effect of the concentration and the incorporation of MWNTs. In addition, the electrical, thermal, mechanical, and microscopic characterizations of these films were performed to examine the effect of the dopants and MWNTs on these properties, along with their surface morphology. The films of electrochemically polymerized PPy were characterized using UV-vis absorption spectra, scanning electron microscopy, and cyclic voltammetry (CV. The results were then compared with the chemical polymerized PPy.

  4. Controllable synthesis of porous LiFePO4 for tunable electrochemical Li-insertion performance

    International Nuclear Information System (INIS)

    Tian, Xiaohui; Zhou, Yingke; Wu, Guan; Wang, Pengcheng; Chen, Jian

    2017-01-01

    Highlights: • A templated freeze-drying method is developed to prepare the porous LiFePO 4 . • The pore size and porosity can be controlled by adjusting the conditions. • The effects of the porous properties on the Li-insertion performances are studied. • The optimized composite presents excellent specific capacity and rate capability. - Abstract: A templated freeze-drying method is developed to prepare the porous LiFePO 4 materials with the controlled pore size and porosity, by conveniently adjusting the size and content of the template in the precursor solution. The morphology and structure of the porous LiFePO 4 materials are characterized and the relavant electrochemical lithium-insertion performances are systematically studied. It’s found that the porous characteristics play a critical role in the lithium-ion intercalation processes and significantly affect the power capability of LiFePO 4 . The optimized porous LiFePO 4 material presents remarkable specific capacity (167 mAh g −1 at 0.1 C), rate capability (151 mAh g −1 at 1 C and 110 mAh g −1 at 10 C) and cycling stability (99.3% retention after 300 cycles at 1 C). These findings demonstrate that the electrochemical performance of the electrode material can be purposely tuned and remarkably improved by the rational design and introduction of the suitable pores, which open up new strategies for the synthesis of advanced porous materials for the lithium-ion power battery applications.

  5. Identification of semicarbazones, thiosemicarbazones and triazine nitriles as inhibitors of Leishmania mexicana cysteine protease CPB.

    Directory of Open Access Journals (Sweden)

    Jörg Schröder

    Full Text Available Cysteine proteases of the papain superfamily are present in nearly all eukaryotes. They play pivotal roles in the biology of parasites and inhibition of cysteine proteases is emerging as an important strategy to combat parasitic diseases such as sleeping sickness, Chagas' disease and leishmaniasis. Homology modeling of the mature Leishmania mexicana cysteine protease CPB2.8 suggested that it differs significantly from bovine cathepsin B and thus could be a good drug target. High throughput screening of a compound library against this enzyme and bovine cathepsin B in a counter assay identified four novel inhibitors, containing the warhead-types semicarbazone, thiosemicarbazone and triazine nitrile, that can be used as leads for antiparasite drug design. Covalent docking experiments confirmed the SARs of these lead compounds in an effort to understand the structural elements required for specific inhibition of CPB2.8. This study has provided starting points for the design of selective and highly potent inhibitors of L. mexicana cysteine protease CPB that may also have useful efficacy against other important cysteine proteases.

  6. Water/ionic liquid/organic three-phase interfacial synthesis of coral-like polypyrrole toward enhanced electrochemical capacitance

    International Nuclear Information System (INIS)

    Hou Linrui; Yuan Changzhou; Li Diankai; Yang Long; Shen Laifa; Zhang Fang; Zhang Xiaogang

    2011-01-01

    Highlights: → Interfacial synthesis strategies are proposed to synthesize PPy samples. → Water/ionic liquid /organic three-phase interface for preparing coral-like PPy. → Coral-like PPy with more ordered structure and better electronic conductivity. → Coral-like PPy owns higher rate performance and better electrochemical stability. - Abstract: Two interfacial synthesis strategies are proposed to synthesize polypyrrole samples for electrochemical capacitors (ECs). In contrast to water/organic two-phase route, unique water/ionic liquid (IL)/organic three-phase interface strategy is first performed to prepare coral-like polypyrrole with even better electrochemical capacitance, where 1-Ethyl-3-methylimidazolium tetrafluoroborate IL, as a 'buffering zone', is set between the water and organic phases to control the morphology and micro-structure of the polypyrrole phase during polymerization. The polypyrrole synthesized by three-phase interfacial route owns more ordered structure, less charge transfer resistance and better electronic conductivity, compared with two-phase method, and delivers larger specific capacitance, higher rate performance and better electrochemical stability at large current densities in 3 M KCl aqueous electrolyte.

  7. Synthesis and Electrochemical Performance of LixMn2-yCoyO4-dCld Cathode Material

    Science.gov (United States)

    2016-06-13

    Synthesis and Electrochemical Performance of LixMn2-yCoyO4-dCld Cathode Material Terrill B. Atwater, Paula C. Latorre, and Ashley L. Ruth U.S...low toxicity, comparable capacity, and low cost. However, this spinel suffers from capacity fading due to fracturing of the cell structure...dopants of interest include compounds containing Group VIII Row 4 (Fe, Co, and Ni) elements, cobalt in particular. In addition to fabrication method

  8. Electrochemical co-reduction synthesis of graphene/nano-gold composites and its application to electrochemical glucose biosensor

    International Nuclear Information System (INIS)

    Wang, Xiaolin; Zhang, Xiaoli

    2013-01-01

    Graphical abstract: - Highlights: • Graphene/nano-Au composite was synthesized by electrochemical co-reduction method in one step. • Glucose oxidase achieves direct electrochemistry on the graphene/nano-Au composite film. • The glucose biosensor shows a high sensitivity of 56.93 μA mM −1 cm −2 toward glucose. • Glucose was detected with a wide linear range and low detection limit. - Abstract: A simple, green and controllable approach was employed for electrochemical synthesize of the graphene/nano-Au composites. The process was that graphene oxide and HAuCl 4 was electrochemically co-reduced onto the glassy carbon electrode (GCE) by cyclic voltammetry in one step. The obtained graphene/nano-Au/GCE exhibited high electrocatalytic activity toward H 2 O 2 , which resulted in a remarkable decrease in the overpotential of H 2 O 2 electrochemical oxidation compared with bare GCE. Such electrocatalytic behavior of the graphene/nano-Au/GCE permitted effective low-potential amperometric biosensing of glucose via the incorporation of glucose oxidase (GOD) with graphene/nano-Au. An obvious advantage of this enzyme electrode (graphene/nano-Au/GOD/GCE) was that the graphene/nano-Au nanocomposites provided a favorable microenvironment for GOD and facilitated the electron transfer between the active center of GOD and electrode. The immobilized GOD showed a direct, reversible redox reaction. Furthermore, the graphene/nano-Au/GOD/GCE was used as a glucose biosensor, displaying a low detection limit of 17 μM (S/N = 3), a high sensitivity of 56.93 μA mM −1 cm −2 , acceptable reproducibility, very good stability, selectivity and anti-interference ability

  9. MnWO{sub 4} nanocapsules: Synthesis, characterization and its electrochemical sensing property

    Energy Technology Data Exchange (ETDEWEB)

    Muthamizh, Selvamani; Suresh, Ranganathan; Giribabu, Krishnamoorthy; Manigandan, Ramadoss; Praveen Kumar, Sivakumar; Munusamy, Settu; Narayanan, Vengidusamy, E-mail: vnnara@yahoo.co.in

    2015-01-15

    Highlights: • Synthesis of MnWO{sub 4} nanocapsules without use of any other external reagent. • High crystalline MnWO{sub 4} was obtained with phase purity. • Electrochemical sensing platform based on MnWO{sub 4} for sensing quercetin. • Micromolar detection ability of MnWO{sub 4} modified GCE. - Abstract: Manganese tungstate (MnWO{sub 4}) was synthesized by surfactant free precipitation method. MnWO{sub 4} was characterized by using various spectroscopic techniques. The phase, crystalline nature and the morphological analysis were carried out using XRD, scanning electron microscopy (SEM), and high resolution transmission electron microscopy (HR-TEM). Further, FT-IR, Raman, and DRS-UV–Vis spectral analysis were carried out in order to ascertain the optical property and the presence of functional groups. From the analysis, the morphology of the MnWO{sub 4} was observed to be in capsules with breadth and thickness were in nm range. The oxidation state of tungsten (W), and manganese (Mn) were investigated using X-ray photo electron spectroscopy (XPS) and electron paramagnetic resonance spectroscopy (EPR). The synthesized MnWO{sub 4} nanocapsules were used to modify glassy carbon electrode (GCE) to detect quercetin.

  10. Facile Synthesis of Flowerlike LiFe5O8 Microspheres for Electrochemical Supercapacitors.

    Science.gov (United States)

    Lin, Ying; Dong, Jingjing; Dai, Jingjing; Wang, Jingping; Yang, Haibo; Zong, Hanwen

    2017-12-18

    Facile synthesis of porous and hollow spinel materials is very urgent due to their extensive applications in the field of energy storage. In present work, flowerlike porous LiFe 5 O 8 microspheres etched for 15, 30, and 45 min (named as p-LFO-15, p-LFO-30, and p-LFO-45, respectively) are successfully synthesized through a facile chemical etching method based on bulk LiFe 5 O 8 (LFO) particles as precursors, and they are applied as electrode materials for high-performance electrochemical capacitors. In particular, the specific surface area of p-LFO-45 reaches 46.13 m 2 g -1 , which is 112 times greater than that of the unetched counterpart. Therefore, the p-LFO-45 electrode can achieve a higher capacitance of 278 F g -1 at a scan rate of 5 mV s -1 than the unetched counterpart. Furthermore, the p-LFO-45 electrode presents a good cycling stability with 78.3% of capacitive retention after 2000 cycles, which is much higher than that of the unetched LFO particles (66%). Therefore, the flowerlike porous LFO microspheres are very promising candidate materials for supercapacitor applications.

  11. Optical properties of cadmium sulfide nanocrystal film prepared by electrochemical synthesis at liquid-liquid interface

    International Nuclear Information System (INIS)

    Luan Yemei; An Maozhong; Lu Guoqi

    2006-01-01

    Dendritic nanocrystalline CdS film was deposited at liquid-liquid interface of surfactants and an electrolyte containing 4 mmol L -1 cadmium chloride (CdCl 2 ) and 16 mmol L -1 thioacetamide (CH 3 CSNH 2 ) with an initial pH value of 5 at 15 deg. C by electrochemical synthesis. The nanofilm was characterized by transmission electron microscopy (TEM), field emission scanning electron microscope (FE-SEM), atomic force microscopy (AFM), ultraviolet visible (UV-vis) absorption spectroscopy and fluorescence spectroscopy. The surface morphology and particle size of the nanofilm were investigated by AFM, SEM and TEM, and the crystalline size was 30-50 nm. The thickness of the nanofilm calculated by optical absorption spectrum was 80 nm. The microstructure and composition of the nanofilm was investigated by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), showing its polycrystalline structure consisting of CdS and Cd. Optical properties of the nanofilm were investigated systematically by UV-vis absorption and fluorescence spectroscopy. A λ onset blue shift compared with bulk CdS was observed in the absorption spectra. Fluorescence spectra of the nanofilm indicated that the CdS nanofilm emitted blue and green light. The nanocomposites film electrode will bring about anodic photocurrent during illumination, showing that the transfer of cavities produces photocurrent

  12. Low-temperature direct synthesis of mesoporous vanadium nitrides for electrochemical capacitors

    Science.gov (United States)

    Lee, Hae-Min; Jeong, Gyoung Hwa; Kim, Sang-Wook; Kim, Chang-Koo

    2017-04-01

    Mesoporous vanadium nitrides are directly synthesized by a one-step chemical precipitation method at a low temperature (70 °C). Structural and morphological analyses reveal that vanadium nitride consist of long and slender nanowhiskers, and mesopores with diameters of 2-5 nm. Compositional analysis confirms the presence of vanadium in the VN structure, along with oxidized vanadium. The cyclic voltammetry and charge-discharge tests indicate that the obtained material stores charges via a combination of electric double-layer capacitance and pseudocapacitance mechanisms. The vanadium nitride electrode exhibits a specific capacitance of 598 F/g at a current density of 4 A/g. After 5000 charge-discharge cycles, the electrode has an equivalent series resistance of 1.42 Ω and retains 83% of its initial specific capacitance. This direct low-temperature synthesis of mesoporous vanadium nitrides is a simple and promising method to achieve high specific capacitance and low equivalent series resistance for electrochemical capacitor applications.

  13. Synthesis and Electrochemical Performance of SiOC-Carbon Nanotube Composite Coatings

    Science.gov (United States)

    Bhandavat, Romil; Cologna, Marco; Raj, Rishi; Singh, Gurpreet

    2012-02-01

    Rechargeable battery anodes made from crystalline Si-based nanostructures have been shown to possess high experimental first cycle capacities (3000 mAh/g), but face challenges in sustaining these capacities beyond initial cycles mainly due to large volume expansion (400 percent) and chemical degradation (pulverization). Polymer-derived ceramic SiOC due to its high thermodynamic stability and nano domain structure could present a viable alternative. Additionally, functionalization of SiOC with carbon nanotubes could result in increased electronic and ionic conductivities in the ceramic. Here, we demonstrate synthesis and electrochemical characterization of SiOC-CNT composite coatings for use in Li-ion battery anode. Materials characterization performed using electron microscopy, Infrared (FT-IR), and X-ray photoelectron spectroscopy suggests non-covalent functionalization of CNT with oxygen moieties in SiOC. Sustained battery capacities of over 700 mAh/g and first cycle columbic efficiencies of about 75 percent were achieved. Future work will involve determination of lithium ion intercalation sites characterized by electron microscopy whereas cyclic voltammetry analysis will access the sequential change in anode chemistry.

  14. Electrochemical synthesis of highly ordered polypyrrole on copper modified aluminium substrates

    International Nuclear Information System (INIS)

    Siddaramanna, Ashoka; Saleema, N.; Sarkar, D.K.

    2014-01-01

    Fabrication of highly ordered conducting polymers on metal surfaces has received a significant interest owing to their potential applications in organic electronic devices. In this context, we have developed a simple method for the synthesis of highly ordered polypyrrole (PPy) on copper modified aluminium surfaces via electrochemical polymerization process. A series of characteristic peaks of PPy evidenced on the infrared spectra of these surfaces confirm the formation of PPy. The X-ray diffraction (XRD) pattern of PPy deposited on copper modified aluminium surfaces also confirmed the deposition of PPy as a sharp and intense peak at 2θ angle of 23° attributable to PPy is observed while this peak is absent on PPy deposited on as-received aluminium surfaces. An atomic model of the interface of PPy/Cu has been presented based on the inter-atomic distance of copper–copper of (1 0 0) plane and the inter-monomer distance of PPy, to describe the ordering of PPy on Cu modified Al surfaces.

  15. Synthesis of naturally-derived macromolecules through simplified electrochemically mediated ATRP

    Directory of Open Access Journals (Sweden)

    Paweł Chmielarz

    2017-11-01

    Full Text Available The flavonoid-based macroinitiator was received for the first time by the transesterification reaction of quercetin with 2-bromoisobutyryl bromide. In accordance with the “grafting from” strategy, a naturally-occurring star-like polymer with a polar 3,3',4',5,6-pentahydroxyflavone core and hydrophobic poly(tert-butyl acrylate (PtBA side arms was synthesized via a simplified electrochemically mediated ATRP (seATRP, utilizing only 78 ppm by weight (wt of a catalytic CuII complex. To demonstrate the possibility of temporal control, seATRP was carried out utilizing a multiple-step potential electrolysis. The rate of the polymerizations was well-controlled by applying optimal potential values during preparative electrolysis to prevent the possibility of intermolecular coupling of the growing polymer arms. This appears to be the first report using on-demand seATRP for the synthesis of QC-(PtBA-Br5 pseudo-star polymers. The naturally-derived macromolecules showed narrow MWDs (Đ = 1.08–1.11. 1H NMR spectral results confirm the formation of quercetin-based polymers. These new flavonoid-based polymer materials may find applications as antifouling coatings and drug delivery systems.

  16. Synthesis of water dispersible polyaniline/poly(styrenesulfonic acid) modified graphene composite and its electrochemical properties

    International Nuclear Information System (INIS)

    Luo, Jing; Jiang, Sisi; Liu, Ren; Zhang, Yongjie; Liu, Xiaoya

    2013-01-01

    A novel water-dispersible polyaniline (PANI)/graphene composite was prepared by the in situ polymerization of aniline on the surface of poly(styrenesulfonic acid) (PSS) coated graphene nanosheets (PSS-GR). The characterization of atomic force microscopy (AFM), transmission electron microscopy (TEM), Raman spectroscopy and Fourier transform infrared (FTIR) spectroscopy confirmed the successful synthesis of PANI/PSS-GR composites and strong interaction between PANI and PSS-GR. The as-synthesized PANI/PSS-GR composite is readily dispersible in water and forms a homogeneous aqueous dispersion which is stable for more than one month. More interestingly, PSS-GR can dope PANI effectively and shift its electroactivity to a neutral or even alkaline environment, making them promising candidates for biological application. In addition, the PANI/PSS-GR composite shows improved electrical conductivity and electrochemical stability compared to the neat polyaniline. Furthermore, the potential use of this composite for detection of ascorbic acid (AA) was investigated. A low detection limit of 5 × 10 −6 M and a linear detection range between 1 × 10 −4 M and 1 × 10 −3 M was attained, indicating the high electrocatalytic ability of this composite. Anticipatedly, the synthesized composite will find promising applications as a novel electrode material in sensors and other devices in virtue of their outstanding characteristics of water-dispersibility, good cycle stability, electroactivity in neutral solution and excellent electrocatalytic ability

  17. Low-temperature direct synthesis of mesoporous vanadium nitrides for electrochemical capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hae-Min [Institute of NT-IT Fusion Technology, Ajou University, 206 Worldcup-ro, Yeongtong-gu, Suwon 16499 (Korea, Republic of); Jeong, Gyoung Hwa [Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Banyeon 100, Ulsan 44919 (Korea, Republic of); Kim, Sang-Wook [Department of Molecular Science and Technology, Ajou University, 206 Worldcup-ro, Yeongtong-gu, Suwon 16499 (Korea, Republic of); Kim, Chang-Koo, E-mail: changkoo@ajou.ac.kr [Department of Chemical Engineering and Department of Energy Systems Research, Ajou University, 206 Worldcup-ro, Yeongtong-gu, Suwon 16499 (Korea, Republic of)

    2017-04-01

    Highlights: • Vanadium nitrides were directly synthesized by a one-step chemical precipitation method. • This method was carried out at a low temperature of 70 °C. • Vanadium nitrides had a specific capacitance of 598 F/g. • The equivalent series resistance of the vanadium nitride electrode was 1.42 Ω after 5000 cycles. - Abstract: Mesoporous vanadium nitrides are directly synthesized by a one-step chemical precipitation method at a low temperature (70 °C). Structural and morphological analyses reveal that vanadium nitride consist of long and slender nanowhiskers, and mesopores with diameters of 2–5 nm. Compositional analysis confirms the presence of vanadium in the VN structure, along with oxidized vanadium. The cyclic voltammetry and charge-discharge tests indicate that the obtained material stores charges via a combination of electric double-layer capacitance and pseudocapacitance mechanisms. The vanadium nitride electrode exhibits a specific capacitance of 598 F/g at a current density of 4 A/g. After 5000 charge-discharge cycles, the electrode has an equivalent series resistance of 1.42 Ω and retains 83% of its initial specific capacitance. This direct low-temperature synthesis of mesoporous vanadium nitrides is a simple and promising method to achieve high specific capacitance and low equivalent series resistance for electrochemical capacitor applications.

  18. Synthesis, structure and electrochemical properties of polyaniline/MoO3 nanobelt composite for lithium battery

    International Nuclear Information System (INIS)

    Mohan, Varishetty Madhu; Chen, Wen; Murakami, Kenji

    2013-01-01

    Graphical abstract: Hydrothermal method was introduced for the synthesis of MoO 3 nanobelts and polyaniline (PANI)/MoO 3 nanobelt composites. The structure and morphology of the samples were studied by X-ray diffraction (XRD), Fourier transform infrared radiation (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis. We can see the presence of polyaniline on the MoO 3 nanobelts surface in the TEM pictures as shown in Fig. (a). The pure MoO 3 nanobelts exhibit the initial specific capacity 276 mAhg −1 , whereas PANI/MoO 3 nanobelt composite shows little low initially 228 mAhg −1 after that it has more stabilized specific capacity with increasing cycle numbers as shown in Fig. (b). The cyclic voltammograms of the PANI/MoO 3 nanobelt composite show better cyclic performance compared to pure MoO 3 nanobelts. The electrochemical impedance spectres were studied for both the pure and PANI/MoO 3 samples at 2.0 and 3.5 potentials. The role of the PANI polymeric component of the composite material seems to be the stabilization of the specific capacity due to probable homogeneous distribution of the induced stress during cycling. Display Omitted Highlights: ► Hydrothermal synthesis of MoO 3 , PANI/MoO 3 nanobelts. ► Samples were characterised by XRD, FTIR, DSC, SEM, TEM, CV and impedance. ► MoO 3 nanobelts cathode battery shows initial specific capacity 276 mAhg −1 . ► PANI/MoO 3 nanobelts show initial specific capacity 228 mAhg −1 but high stability. ► PANI/MoO 3 sample studies by impedance at the potentials of 2.0 and 3.5 V. -- Abstract: The MoO 3 nanobelts and polyaniline (PANI)/MoO 3 nanobelt composite were synthesized using hydrothermal method. The crystal structure and morphology of the samples were studied by X-ray diffraction (XRD), Fourier transform infrared radiation (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Differential scanning calorimetric (DSC) and thermo

  19. Synthesis and electrochemical characterization of nano-sized Ag_4Sn particles as anode material for lithium-ion batteries

    International Nuclear Information System (INIS)

    Schmuelling, Guido; Oehl, Nikolas; Fromm, Olga; Knipper, Martin; Kolny-Olesiak, Joanna; Plaggenborg, Thorsten; Parisi, Jürgen; Winter, Martin; Placke, Tobias

    2016-01-01

    For the first time, sub 10 nm sized intermetallic Ag_4Sn particles are prepared via an aqueous synthesis route in order to improve the electrochemical performance of pure Sn nanoparticles. High-resolution transmission electron microscopy, X-ray diffraction and thermogravimetric analysis are used to investigate the morphology, crystal structure and particle surface of the as prepared Ag_4Sn nanoparticles. In addition, galvanostatic cycling and cyclic voltammetry measurements are carried out to characterize the electrochemical behavior of the particles. Upon lithiation and de-lithiation a phase transformation from Ag_4Sn to Ag_3Sn is observed, which has not been reported so far. The intermetallic nanoparticle-based anode delivers a specific de-lithiation capacity of 460 mAhg"−"1 for more than 150 cycles.

  20. Synthesis and electrochemical performance of surface-modified nano-sized core/shell tin particles for lithium ion batteries

    International Nuclear Information System (INIS)

    Schmuelling, Guido; Meyer, Hinrich-Wilhelm; Placke, Tobias; Winter, Martin; Oehl, Nikolas; Knipper, Martin; Kolny-Olesiak, Joanna; Plaggenborg, Thorsten; Parisi, Jürgen

    2014-01-01

    Tin is able to lithiate and delithiate reversibly with a high theoretical specific capacity, which makes it a promising candidate to supersede graphite as the state-of-the-art negative electrode material in lithium ion battery technology. Nevertheless, it still suffers from poor cycling stability and high irreversible capacities. In this contribution, we show the synthesis of three different nano-sized core/shell-type particles with crystalline tin cores and different amorphous surface shells consisting of SnO x and organic polymers. The spherical size and the surface shell can be tailored by adjusting the synthesis temperature and the polymer reagents in the synthesis, respectively. We determine the influence of the surface modifications with respect to the electrochemical performance and characterize the morphology, structure, and thermal properties of the nano-sized tin particles by means of high-resolution transmission electron microscopy, x-ray diffraction, and thermogravimetric analysis. The electrochemical performance is investigated by constant current charge/discharge cycling as well as cyclic voltammetry. (paper)

  1. Controlled synthesis of MnSn(OH)6/graphene nanocomposites and their electrochemical properties as capacitive materials

    International Nuclear Information System (INIS)

    Wang Gongkai; Sun Xiang; Lu Fengyuan; Yu Qingkai; Liu Changsheng; Lian Jie

    2012-01-01

    We report the synthesis of novel MnSn(OH) 6 /graphene nanocomposites produced by a co-precipitation method and their potential application for electrochemical energy storage. The hydroxide decorated graphene nanocomposites display better performance over pure MnSn(OH) 6 nanoparticles because the graphene sheets act as conductive bridges improving the ionic and electronic transport. The crystallinity of MnSn(OH) 6 nanoparticles deposited on the surface of graphene sheets also impacts the capacitive properties as electrodes. The maximum capacitance of 31.2 F/g (59.4 F/g based on the mass of MnSn(OH) 6 nanoparticles) was achieved for the sample with a low degree of crystallinity. No significant degradation of capacitance occurred after 500 cycles at a current density of 1.5 A/g in 1 M Na 2 SO 4 aqueous solution, indicating an excellent electrochemical stability. The results serve as an example demonstrating the potential of integrating highly conductive graphene networks into binary metal hydroxide in improving the performance of active electrode materials for electrochemical energy storage applications. - Graphical abstract: Graphite oxide (GO) can be synthesized by oxidizing graphite using Hummers method. Graphene was reduced from GO by thermal exfoliation. In this work, MnSn(OH) 6 /graphene nano-composites were synthesized by a simple co-precipitation method and their electrochemical performances have been explored. Highlights: ► Noval MnSn(OH) 6 /graphene nano-composites were synthesized. ► Microstructure can be tailored by changing the reaction temperature and time. ► Crystallinity of MnSn(OH) 6 nanoparticles impacts capacitive properties as electrode. ► Nano-composites display improved electrochemical performance over MnSn(OH) 6 alone. ► Results serve as an example demonstrating the potential for energy storage.

  2. Rapid synthesis of graphene/amorphous α-MnO2 composite with enhanced electrochemical performance for electrochemical capacitor

    International Nuclear Information System (INIS)

    Pang, Mingjun; Long, Guohui; Jiang, Shang; Ji, Yuan; Han, Wei; Wang, Biao; Liu, Xilong; Xi, Yunlong

    2015-01-01

    Highlights: • Graphene/MnO 2 is successfully fabricated by a facile co-precipitation method. • The graphene/MnO 2 electrode reaches 367 Fg −1 in 1 M KOH electrolyte. • The electrode exhibits good cycling performance of 73.9% retention after 1000 cycles. - Abstract: Nanostructured graphene/amorphous α-MnO 2 composites have been synthesized by a facile co-precipitation method under the alkaline condition, in which graphene nanosheets as a supporting substrate to grow MnO 2 . Characterizations of prepared samples’ morphology and microstructures indicate MnO 2 is successfully formed on the surface of graphene by electrostatic interaction. Moreover, the electrochemical properties of the synthesized electrode materials for supercapacitors are studied in a three-electrode experimental setup using a 1 M KOH aqueous solution as the electrolyte. As a result, the specific capacitance of graphene/MnO 2 composite (weight ratio of graphene to MnO 2 is 1:1) determined by a galvanostatic charge–discharge method at a current density of 1 Ag −1 reaches 367 Fg −1 , which is 1.8 and 4.6 fold higher than that of pure graphene and MnO 2 . The capacity retention of the graphene/MnO 2 composite is 73.9% of the original capacitance after 1000 cycles, indicating graphene/MnO 2 composite is a promising electrode material for supercapacitors

  3. Effect of the synthesis method on the microstructure, morphology and electrochemical characteristics of α-Fe2O3 anodes for Lithium ion batteries

    International Nuclear Information System (INIS)

    Uzunov, I.; Klissurski, D.; Uzunova, S.; Aleksandrova, A.

    2009-01-01

    Effect of the synthesis method and temperature on some structural characteristics and electrochemical behaviour was investigated for samples of α-Fe 2 O 3 prepared from different precursors. The phase composition, morphology and crystallinity of the obtained materials were determined by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). The electrochemical behaviour of the synthesized samples was studied within voltage range 0.01-2.5V and various current densities. The electrochemical behaviour of the obtained active anode materials was found to depend mostly on the ratio between mean particle size (MPS) and mean coherent domain size (MCDS). It was found that the ratio depends on the synthesis method and calcination temperature. By optimization of the synthesis processes α-Fe 2 O 3 was prepared with optimal microstructure and particle size, a promising anode material for lithium ion batteries. (authors)

  4. Rapid synthesis of graphene/amorphous α-MnO{sub 2} composite with enhanced electrochemical performance for electrochemical capacitor

    Energy Technology Data Exchange (ETDEWEB)

    Pang, Mingjun [Key Laboratory of Physics and Technology for Advanced Batteries, Ministry of Education, College of Physics, Jilin University, Jiefang Road 2519, Changchun 130012 (China); Long, Guohui [College of Life Sciences, Jilin Agricultural University, Changchun 130118 (China); Jiang, Shang [State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012 (China); Ji, Yuan, E-mail: jiyuan@jlu.edu.cn [Key Laboratory of Physics and Technology for Advanced Batteries, Ministry of Education, College of Physics, Jilin University, Jiefang Road 2519, Changchun 130012 (China); Han, Wei [Key Laboratory of Physics and Technology for Advanced Batteries, Ministry of Education, College of Physics, Jilin University, Jiefang Road 2519, Changchun 130012 (China); Wang, Biao [Key Laboratory of Physics and Technology for Advanced Batteries, Ministry of Education, College of Physics, Jilin University, Jiefang Road 2519, Changchun 130012 (China); School of Science, University of Science and Technology Liaoning, Anshan 114051 (China); Liu, Xilong; Xi, Yunlong [Key Laboratory of Physics and Technology for Advanced Batteries, Ministry of Education, College of Physics, Jilin University, Jiefang Road 2519, Changchun 130012 (China)

    2015-04-15

    Highlights: • Graphene/MnO{sub 2} is successfully fabricated by a facile co-precipitation method. • The graphene/MnO{sub 2} electrode reaches 367 Fg{sup −1} in 1 M KOH electrolyte. • The electrode exhibits good cycling performance of 73.9% retention after 1000 cycles. - Abstract: Nanostructured graphene/amorphous α-MnO{sub 2} composites have been synthesized by a facile co-precipitation method under the alkaline condition, in which graphene nanosheets as a supporting substrate to grow MnO{sub 2}. Characterizations of prepared samples’ morphology and microstructures indicate MnO{sub 2} is successfully formed on the surface of graphene by electrostatic interaction. Moreover, the electrochemical properties of the synthesized electrode materials for supercapacitors are studied in a three-electrode experimental setup using a 1 M KOH aqueous solution as the electrolyte. As a result, the specific capacitance of graphene/MnO{sub 2} composite (weight ratio of graphene to MnO{sub 2} is 1:1) determined by a galvanostatic charge–discharge method at a current density of 1 Ag{sup −1} reaches 367 Fg{sup −1}, which is 1.8 and 4.6 fold higher than that of pure graphene and MnO{sub 2}. The capacity retention of the graphene/MnO{sub 2} composite is 73.9% of the original capacitance after 1000 cycles, indicating graphene/MnO{sub 2} composite is a promising electrode material for supercapacitors.

  5. Electrochemical Synthesis of Graphene/MnO2 Nano-Composite for Application to Supercapacitor Electrode.

    Science.gov (United States)

    Jeong, Kwang Ho; Lee, Hyeon Jeong; Simpson, Michael F; Jeong, Mun

    2016-05-01

    Graphene/MnO2 nano-composite was electrochemically synthesized for application to an electrode material for electrochemical supercapacitors. The nanosized needle-like MnO2 was obtained by use of a graphene substrate. The prepared composite exhibited an ideal supercapacitive behavior. A capacitance retention of 94% was achieved with a 4 h deposition time (an initial capacitance of 574 mF/cm2 at a scan rate of 20 mV/s) and the retention declined with further deposition time. The results demonstrate enhanced contact between the electrode and electrolyte and improved power density as an electrochemical capacitor.

  6. Synthesis and electrochemical properties of tin oxide-based composite by rheological technique

    International Nuclear Information System (INIS)

    He Zeqiang; Li Xinhai; Xiong Lizhi; Wu Xianming; Xiao Zhuobing; Ma Mingyou

    2005-01-01

    Novel rheological technique was developed to synthesize tin oxide-based composites. The microstructure, morphology, and electrochemical performance of the materials were investigated by X-ray diffraction, scanning electron microscopy and electrochemical methods. The particles of tin oxide-based materials form an inactive matrix. The average size of the particles is about 150 nm. The material delivers a charge capacity of more than 570 mAh g -1 . The capacity loss per cycle is about 0.15% after being cycled 30 times. The good electrochemical performance indicates that this kind of tin oxide-based material is promising anode for lithium-ion battery

  7. The electrochemical synthesis of poly(pyrrole-co-o-anisidine) on 3102 aluminum alloy and its corrosion protection properties

    International Nuclear Information System (INIS)

    Mert, B. Dogru; Yazici, B.

    2011-01-01

    Research highlights: → The electrochemical synthesis of strongly adherent, uniform polypyrrole (PPy) and poly(pyrrole-co-o-anisidine) coatings were successfully achieved on 3102 aluminum alloy from 0.1 M monomer (pyrrole and pyrrole:o-anisidine, 8:2) containing oxalic acid by means of the cyclic voltammetry technique. → The results were showed that the water permeation of copolymer coating is lower than PPy. → This study was showed that copolymer is suitable coating for protection of 3102 Al alloy against corrosion. - Abstract: The electrochemical syntheses of polypyrrole (PPy) and poly(pyrrole-co-o-anisidine) were achieved on 3102 aluminum alloy (Al) from 0.1 M monomer (pyrrole:o-anisidine, 8:2) containing 0.4 M oxalic acid solution using the cyclic voltammetry technique. The synthesized films were characterized by FT-IR spectroscopy. The thermal stability of films was determined by thermogravimetric analysis (TGA) technique. Surface morphologies were characterized by scanning electron microscope (SEM) images. The potential of zero charge (pzc) of Al was determined using electrochemical impedance spectroscopy (EIS). The corrosion behavior of samples was investigated with open circuit potential (E ocp )-time, EIS, and anodic polarization techniques. It was found that copolymer coated Al provides better barrier property against of corrosion in 3.5% NaCl solution.

  8. Electrochemical synthesis of 1D core-shell Si/TiO2 nanotubes for lithium ion batteries

    Science.gov (United States)

    Kowalski, Damian; Mallet, Jeremy; Thomas, Shibin; Nemaga, Abirdu Woreka; Michel, Jean; Guery, Claude; Molinari, Michael; Morcrette, Mathieu

    2017-09-01

    Silicon negative electrode for lithium ion battery was designed in the form of self-organized 1D core-shell nanotubes to overcome shortcomings linked to silicon volume expansion upon lithiation/delithiation typically occurring with Si nanoparticles. The negative electrode was formed on TiO2 nanotubes in two step electrochemical synthesis by means of anodizing of titanium and electrodeposition of silicon using ionic liquid electrolytes. Remarkably, it was found that the silicon grows perpendicularly to the z-axis of nanotube and therefore its thickness can be precisely controlled by the charge passed in the electrochemical protocol. Deposited silicon creates a continuous Si network on TiO2 nanotubes without grain boundaries and particle-particle interfaces, defining its electrochemical characteristics under battery testing. In the core-shell system the titania nanotube play a role of volume expansion stabilizer framework holding the nanostructured silicon upon lithiation/delithiation. The nature of Si shell and presence of titania core determine stable performance as negative electrode tested in half cell of CR2032 coin cell battery.

  9. Controllable Electrochemical Synthesis of Reduced Graphene Oxide Thin-Film Constructed as Efficient Photoanode in Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Soon Weng Chong

    2016-01-01

    Full Text Available A controllable electrochemical synthesis to convert reduced graphene oxide (rGO from graphite flakes was introduced and investigated in detail. Electrochemical reduction was used to prepare rGO because of its cost effectiveness, environmental friendliness, and ability to produce rGO thin films in industrial scale. This study aimed to determine the optimum applied potential for the electrochemical reduction. An applied voltage of 15 V successfully formed a uniformly coated rGO thin film, which significantly promoted effective electron transfer within dye-sensitized solar cells (DSSCs. Thus, DSSC performance improved. However, rGO thin films formed in voltages below or exceeding 15 V resulted in poor DSSC performance. This behavior was due to poor electron transfer within the rGO thin films caused by poor uniformity. These results revealed that DSSC constructed using 15 V rGO thin film exhibited high efficiency (η = 1.5211% attributed to its higher surface uniformity than other samples. The addition of natural lemon juice (pH ~ 2.3 to the electrolyte accelerated the deposition and strengthened the adhesion of rGO thin film onto fluorine-doped tin oxide (FTO glasses.

  10. One-step electrochemical synthesis of a graphene–ZnO hybrid for improved photocatalytic activity

    International Nuclear Information System (INIS)

    Wei, Ang; Xiong, Li; Sun, Li; Liu, Yanjun; Li, Weiwei; Lai, Wenyong; Liu, Xiangmei; Wang, Lianhui; Huang, Wei; Dong, Xiaochen

    2013-01-01

    Graphical abstract: - Highlights: • Graphene–ZnO hybrid was synthesized by one-step electrochemical deposition. • Graphene–ZnO hybrid presents a special structure and wide UV–vis absorption spectra. • Graphene–ZnO hybrid exhibits an exceptionally higher photocatalytic activity for the degradation of dye methylene blue. - Abstract: A graphene–ZnO (G-ZnO) hybrid was synthesized by one-step electrochemical deposition. During the formation of ZnO nanostructure by cathodic electrochemical deposition, the graphene oxide was electrochemically reduced to graphene simultaneously. Scanning electron microscope images, X-ray photoelectron spectroscopy, X-ray diffraction, Raman spectra, and UV–vis absorption spectra indicate the resulting G-ZnO hybrid presents a special structure and wide UV–vis absorption spectra. More importantly, it exhibits an exceptionally higher photocatalytic activity for the degradation of dye methylene blue than that of pure ZnO nanostructure under both ultraviolet and sunlight irradiation

  11. Process Design for Size-Controlled Flame Spray Synthesis of Li4Ti5O12 and Electrochemical Performance

    Directory of Open Access Journals (Sweden)

    Waser Oliver

    2017-03-01

    Full Text Available Inexpensive synthesis of electroceramic materials is required for efficient energy storage. Here the design of a scalable process, flame spray pyrolysis (FSP, for synthesis of size-controlled nanomaterials is investigated focusing on understanding the role of air entrainment (AE during their aerosol synthesis with emphasis on battery materials. The AE into the enclosed FSP reactor is analysed quantitatively by computational fluid dynamics (CFD and calculated temperatures are verified by Fourier transform infrared spectroscopy (FTIR. Various Li4Ti5O12 (LTO particle compositions are made and characterized by N2 adsorption, electron microscopy and X-ray diffraction while the electrochemical performance of LTO is tested at various charging rates. Increasing AE decreases recirculation in the enclosing tube leading to lower reactor temperatures and particle concentrations by air dilution as well as shorter and narrower residence time distributions. As a result, particle growth by coagulation - coalescence decreases leading to smaller primary particles that are mostly pure LTO exhibiting high C-rate performance with more than 120 mAh/g galvanostatic specific charge at 40C, outperforming commercial LTO. The effect of AE on FSP-made particle characteristics is demonstrated also in combustion synthesis of LiFePO4 and ZrO2.

  12. Spectroscopic evaluation of Co(II), Ni(II) and Cu(II) complexes derived from thiosemicarbazone and semicarbazone

    Science.gov (United States)

    Chandra, Sulekh; Kumar, Anil

    2007-12-01

    Co(II), Ni(II) and Cu(II) complexes were synthesized with thiosemicarbazone (L 1) and semicarbazone (L 2) derived from 2-acetyl furan. These complexes were characterized by elemental analysis, molar conductance, magnetic moment, mass, IR, electronic and EPR spectral studies. The molar conductance measurement of the complexes in DMSO corresponds to non-electrolytic nature. All the complexes are of high-spin type. On the basis of different spectral studies six coordinated geometry may be assigned for all the complexes except Co(L) 2(SO 4) and Cu(L) 2(SO 4) [where L = L 1 and L 2] which are of five coordinated square pyramidal geometry.

  13. Facile synthesis of reduced graphene oxide/CoWO4 nanocomposites with enhanced electrochemical performances for supercapacitors

    International Nuclear Information System (INIS)

    Xu, Xiaowei; Shen, Jianfeng; Li, Na; Ye, Mingxin

    2014-01-01

    Highlights: • RGO/CoWO 4 composites were successfully prepared through a facile hydrothermal method. • RGO/CoWO 4 composites show much higher specific capacitances than pure CoWO 4 . • Enhanced electrical conductivity leads to superior electrochemical performance. - Abstract: A facile one-pot hydrothermal method was provided for synthesis of the reduced graphene oxide-cobalt tungstate (RGO/CoWO 4 ) nanocomposites with the enhanced electrochemical performances for supercapacitors for the first time. The resulting nanocomposites are comprised of CoWO 4 nanospheres that are well-anchored on graphene sheets by in situ reducing. The prepared RGO/CoWO 4 nanocomposites have been thoroughly characterized by Fourier–transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, Thermogravimetric analysis, Scanning electron microscopy, Transmission electron microscopy, X-ray photoelectron spectroscopy, and N 2 adsorption–desorption. Importantly, the prepared nanocomposites exhibit superior electrochemical performance to CoWO 4 as electrodes for supercapacitors. As a result, RGO/CoWO 4 nanocomposites with 91.6 wt% CoWO 4 content achieved a specific capacitance about 159.9 F g −1 calculated from the CV curves at 5 mV s −1 , which was higher than that of CoWO 4 (60.6 F g −1 ). The good electrochemical performance can be attributed to the increased electrical conductivity and the creation of new active sites due to the synergetic effect of RGO and CoWO 4 nanospheres. The cyclic stability tests demonstrated capacitance retention of about 94.7% after 1000 cycles, suggesting the potential application of RGO/CoWO 4 nanocomposites in energy-storage devices

  14. Synthesis and electrochemical properties of binary MgTi and ternary MgTiX (X=Ni, Si) hydrogen storage alloys

    NARCIS (Netherlands)

    Gobichettipalayam Manivasagam, T.; Iliksu, M.; Danilov, D.L.; Notten, P.H.L.

    2017-01-01

    Mg-based hydrogen storage alloys are promising candidate for many hydrogen storage applications because of the high gravimetric hydrogen storage capacity and favourable (de)hydrogenation kinetics. In the present study we have investigated the synthesis and electrochemical hydrogen storage properties

  15. Effects of size reduction on the structure and magnetic properties of core-shell Ni3Si/silica nanoparticles prepared by electrochemical synthesis

    Czech Academy of Sciences Publication Activity Database

    Pigozzi, G.; Mukherji, D.; Elerman, Y.; Strunz, Pavel; Gilles, R.; Hoelzel, M.; Barbier, B.; Schmutz, P.

    2014-01-01

    Roč. 584, JAN (2014), s. 119-127 ISSN 0925-8388 Institutional support: RVO:61389005 Keywords : intermetallics * nanostructured materials * transition metal alloys and compounds * electrochemical synthesis * crystal structure * magnetic measurements Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.999, year: 2014

  16. Synthesis of palladium@gold nanoalloys/nitrogen and sulphur-functionalized multiple graphene aerogel for electrochemical detection of dopamine

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ruiyi; Yang, Tingting [School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122 (China); Li, Zaijun, E-mail: zaijunli@jiangnan.edu.cn [School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122 (China); Key Laboratory of Food Colloids and Biotechnology, Ministry of Education, Wuxi 214122 (China); Gu, Zhiguo; Wang, Guangli; Liu, Junkang [School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122 (China)

    2017-02-15

    Integration of noble metal nanomaterials on graphene nanosheets potentially paves one way to improve their electronic, chemical and electrochemical properties. The study reported synthesis of palladium@gold nanoalloys/nitrogen and sulphur-functionalized multiple graphene aerogel composite (Pd@Au/N,S-MGA). The as-prepared composite offers a well-defined three-dimensional architecture with rich of mesopores. The Pd@Au nanoalloys were dispersed on the graphene framework networks and their active sites were fully exposed. The unique structure achieves to ultra high electron/ion conductivity, electrocatalytic activity and structural stability. The sensor based on the Pd@Au/N,S-MGA creates ultrasensitive electrochemical response towards dopamine due to significantly electrochemical synergy between Pd, Au and N,S-MGA. Its differential pulse voltammetric signal linearly increases with the increase of dopamine concentration in the range from 1.0 × 10{sup −9} M to 4.0 × 10{sup −5} M with the detection limit of 3.6 × 10{sup −10} M (S/N = 3). The analytical method provides the advantage of sensitivity, reproducibility, rapidity and long-term stability. It has been successfully applied in the detection of trace dopamine in biological samples. The study also opens a window on the electronic properties of graphene aerogel and metal nanomaterials as well their nanohybrids to meet needs of further applications as nanoelectronics in diagnosis, bioanalysis and catalysis. - Graphical abstract: We reported a new palladium@gold nanoalloys/nitrogen and sulphur-functionalized multiple graphene aerogel. The sensor based on the nanohybrid exhibits ultrahigh sensitivity, reproducibility and stability to electrochemical detection of dopamine. - Highlights: • We reported Pd@A/nitrogen and sulphur-functionalized multiple graphene aerogel. • The nanohybrid offers unique three-dimensional architecture with rich of mesopores. • The architecture achieve to ultrahigh

  17. Synthesis of palladium@gold nanoalloys/nitrogen and sulphur-functionalized multiple graphene aerogel for electrochemical detection of dopamine

    International Nuclear Information System (INIS)

    Li, Ruiyi; Yang, Tingting; Li, Zaijun; Gu, Zhiguo; Wang, Guangli; Liu, Junkang

    2017-01-01

    Integration of noble metal nanomaterials on graphene nanosheets potentially paves one way to improve their electronic, chemical and electrochemical properties. The study reported synthesis of palladium@gold nanoalloys/nitrogen and sulphur-functionalized multiple graphene aerogel composite (Pd@Au/N,S-MGA). The as-prepared composite offers a well-defined three-dimensional architecture with rich of mesopores. The Pd@Au nanoalloys were dispersed on the graphene framework networks and their active sites were fully exposed. The unique structure achieves to ultra high electron/ion conductivity, electrocatalytic activity and structural stability. The sensor based on the Pd@Au/N,S-MGA creates ultrasensitive electrochemical response towards dopamine due to significantly electrochemical synergy between Pd, Au and N,S-MGA. Its differential pulse voltammetric signal linearly increases with the increase of dopamine concentration in the range from 1.0 × 10"−"9 M to 4.0 × 10"−"5 M with the detection limit of 3.6 × 10"−"1"0 M (S/N = 3). The analytical method provides the advantage of sensitivity, reproducibility, rapidity and long-term stability. It has been successfully applied in the detection of trace dopamine in biological samples. The study also opens a window on the electronic properties of graphene aerogel and metal nanomaterials as well their nanohybrids to meet needs of further applications as nanoelectronics in diagnosis, bioanalysis and catalysis. - Graphical abstract: We reported a new palladium@gold nanoalloys/nitrogen and sulphur-functionalized multiple graphene aerogel. The sensor based on the nanohybrid exhibits ultrahigh sensitivity, reproducibility and stability to electrochemical detection of dopamine. - Highlights: • We reported Pd@A/nitrogen and sulphur-functionalized multiple graphene aerogel. • The nanohybrid offers unique three-dimensional architecture with rich of mesopores. • The architecture achieve to ultrahigh electron

  18. Microwave synthesis of metal nanocatalysts for the electrochemical oxidation of small biomolecules

    DEFF Research Database (Denmark)

    Jensen, Kathrine Schiørring Steen; Sun, Hongyu; Werchmeister, Rebecka Maria Larsen

    2017-01-01

    Electrochemical oxidation of small biomolecules provides an approach to generate clean energy from a sustainable resource. It serves as a principle for anode reactions in fuel cells to convert energy stored in chemical bonds into electrical power. Efficient and robust nanocatalysts are essential ...

  19. Synthesis and characterization of Nitrogen-doped &CaCO3-decorated reduced graphene oxide nanocomposite for electrochemical supercapacitors

    International Nuclear Information System (INIS)

    Ghouri, Zafar Khan; Barakat, Nasser A.M.; Alam, Al-Mahmnur; Alsoufi, Mohammad S.; Bawazeer, Tahani M.; Mohamed, Ahmed F.; Kim, Hak Yong

    2015-01-01

    Alone, it is expected, and also was experimentally proved, that calcium carbonate and reduced graphene oxide do have negligible specific capacitance due to the chemical composition of both materials. However, synthesis of CaCO 3 on the form of very thin sporadic layer attaching rGO results in dramatic increase in the specific capacitance of the obtained composite due to formation of the electrochemical double layer at the interfacial area. Moreover, the specific capacitance could be further enhanced by nitrogen-doping of the rGO sheets. Typically, a novel N-rGO/CaCO 3 composite has been successfully synthesized by heat reflux strategy with graphite powder, calcium acetate and urea as raw materials.The composite was characterized by X-Ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), field-emission scanning electron microscopy (FESEM), coupled with rapid EDAX (energy dispersive analysis of X-Ray) and X-ray photoelectron spectroscopy. The utilized physiochemical characterizations indicated that the final prepared composite can be demonstrated as N-doped rGO decorated by very thin discrete layer from calcium carbonate. Supercapacitive performance of N-rGO/CaCO 3 composite has been investigated by cyclic voltammetry (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy in 1 M KOH solution. The results reveal that the N-rGO/CaCO 3 composite delivers a large specific capacitance of as high as 214 Fg −1 and 188 Fg −1 at 5 mV s −1 and 1.0 Ag −1 , according to CV and galvanostatic charge-discharge tests, respectively; while the CaCO 3 , rGO, rGO/CaCO 3 , N-rGO based electrodes has a poor electrochemical performance at the same conditions. Moreover, the as-prepared composite exhibited excellent long cycle stability with about 88.7% specific capacitance retained after 10,000 cycles.

  20. Electrochemical synthesis, in situ spectroelectrochemistry of conducting indole-titanium dioxide and zinc oxide polymer nanocomposites for rechargeable batteries

    International Nuclear Information System (INIS)

    Parvin, Mohammad Hadi; Pirnia, Mahsa; Arjomandi, Jalal

    2015-01-01

    Highlights: • Two novel hybrid materials-based conducting PIn rechargeable batteries were developed. • The charge-discharging behavior of PIn-nanocomposite batteries were studied. • The characterization of samples has been done by in situ spectroelectrochemical method. • PIn-TiO 2 and ZnO nanocomposites were synthesized electrochemically on Au and ITO. • The PIn-TiO 2 and ZnO nanocomposites resistances were less than PIn. - Abstract: Electrochemical synthesis, in situ spectroelectrochemistry of conducting polyindole (PIn), polyindole-TiO 2 (PIn-TiO 2 ) and polyindole-ZnO (PIn-ZnO) nanocomposites were investigated. The PIn and polymer nanocomposites were tested electrochemically for rechargeable batteries. The films were characterized by means of CVs, in situ UV-visible, FT-IR spectroscopies, in situ resistivity measurements, energy dispersive X-ray (EDX), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The charge-discharging behavior of a Zn/1 M ZnSO 4 /PIn cell with a capacity of around 90 Ah Kg −1 and on open circuit potential of around 1.45 V was compared with Zn/1 M ZnSO 4 /PIn-nanocomposite. The potential differences of redox couples (ΔE) for nanocomposites films show very good reversibility. A positive shift of potential was observed for polymer nanocomposites during redox scan. A significant variability was observed for in situ conductivity of the PIn and polymer nanocomposites. During in situ UV-visible and FT-IR measurements, intermediate spectroscopic behavior and positive shifts of wavelengths were observed for PIn and polymer nanocomposites. The SEM, TEM and EDX of nanocomposite films show the presence of nano particle in PIn.

  1. Solvothermal Synthesis of Fe2O3 Loaded Activated Carbon as Electrode Materials for High-performance Electrochemical Capacitors

    International Nuclear Information System (INIS)

    Li, Ying; Kang, Litao; Bai, Gailing; Li, Peiyang; Deng, Jiachun; Liu, Xuguang; Yang, Yongzhen; Gao, Feng; Liang, Wei

    2014-01-01

    This article describes a facile solvothermal synthesis method to prepare Fe 2 O 3 /AC composites for electrochemical capacitors from Iron (III) chloride hexahydrate (FeCl 3 ·6H 2 O), activated carbon (AC, from petroleum coke), and four different precipitants (i.e., NaOH, CH 3 COONa, HMT, CO(NH 2 ) 2 ). X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS) and Thermogravimetric (TG) analysis show that the products consisted of nanosized α-Fe 2 O 3 (weight ratios: 48.1, 47.9, 44.2, 44.3%) loaded onto AC particles (∼ 20 μm). Significantly, both kind and dosage of precipitants exhibit effects on the specific capacitances of Fe 2 O 3 /AC composites. The highest specific capacitance reaches up to 240 F g −1 (at a current density of 1 A g −1 in 6 M KOH aqueous electrolyte) when the molar ratio of CH 3 COONa: FeCl 3 is 9. On the other hand, the sample prepared with NaOH: FeCl 3 molar ratio being 1.5 exhibits excellent rate capability with specific capacitance of 215 F g −1 at 1 A g −1 , and 89.3, 82.3, 78.1, 72.6 and 65.1% capacity retention at 2, 5, 10, 20, and 40 A g −1 , respectively. These electrochemical performances are superior to other materials consisted of Fe 2 O 3 /carbon nanotube (CNT), graphene oxide (GO) or reduced graphene oxide (rGO) composites, demonstrating the great potential of Fe 2 O 3 /AC composites in the development of high-performance electrode materials for electrochemical capacitors

  2. Synthesis and electrochemical properties of novel, donor–acceptor pyrrole derivatives with 1,8-naphthalimide units and their polymers

    International Nuclear Information System (INIS)

    Ledwon, Przemyslaw; Brzeczek, Alina; Pluczyk, Sandra; Jarosz, Tomasz; Kuznik, Wojciech; Walczak, Krzysztof; Lapkowski, Mieczyslaw

    2014-01-01

    A new class of bipolar monomers with pyrrole or thiophene–pyrrole–thiophene as electron donor and 1,8-naphthalimide as electron acceptor unit is reported. Donor–acceptor conjugated polymers were generated electrochemically. The synthesis of monomers, optical, electrochemical and spectroelectrochemical properties supported by theoretical calculations are presented. 1,8-naphthalimide units were attached directly to pyrrole in compounds 1a and 2a or by different bridges in the case of 1b and 2b. Intra-molecular donor–acceptor interactions of the monomers and its polymers were investigated using cyclic voltammetry, in-situ UV–Vis-NIR, electron spin resonance (ESR) spectroelectrochemistry and fluorescence spectroscopy. Studied compounds present large discrepancy (up to 1.31 eV for 2a) between energy gap values determined through electrochemical and optical measurements. The Time-dependent density functional theory (TDDFT) calculations help to explain this discrepancy. This is caused by weak HOMO to LUMO transition, 2000 times weaker than HOMO −2 to LUMO or HOMO to LUMO +1 transition. Altering the structure of monomers yields different stability and properties of obtained polymers. The p- and n-doping processes are separated. Anions are localized mainly on 1,8-naphthalimide units. Cations are localized mainly on pyrrole or thiophene–pyrrole–thiophene moiety and their polymer chains. Attachment of the additional thiophene units decreases the oxidation potential of the monomer and reduces the influence of the steric hindrance between 1,8-naphthalimide moiety and polymer/oligomers chain. This new class of model compounds is promising for use as a material with enhanced charge separation for wide range of optoelectronic, electrochromic and photovoltaic applications

  3. Chromium(III) Complex Obtained from Dipicolinic Acid: Synthesis, Characterization, X-Ray Crystal Structure and Electrochemical Studies

    Energy Technology Data Exchange (ETDEWEB)

    Ghasemi, Khaled; Rezvani, Ali Reza; Ghasemi, Fatemeh [Univ. of Sistan and Baluchestan, Zahedan (Iran, Islamic Republic of); Razak, Ibrahim Abdul; Rosli, Mohd Mustaqim [Universiti Sains Malaysia, Penang (Malaysia)

    2013-10-15

    The synthesis, X-ray crystallography, spectroscopic (IR, UV-vis), and electrochemical properties of the title compound, [H{sub 3}O][Cr(dipic){sub 2}] [H{sub 3}O{sup +}.Cl{sup -}] (1), (H{sub 2}dipic = 2,6-pyridinedicarboxylic acid), are reported. This complex crystallizes in the monoclinic space group Cc with a = 14.9006(10) A, b = 12.2114(8) A, c = 8.6337(6) A, α = 90.00 .deg., β = 92.7460(10) .deg., γ = 90.00 .deg., and V = 1569.16(18) A3 with Z = 4. The hydrogen bonding and noncovalent interactions play roles in the stabilization of the structure. In order to gain a better understanding of the most important geometrical parameters in the structure of the complex, atoms in molecules (AIM) method at B3LYP/6-31G level of theory has been employed.

  4. Chemical and electrochemical synthesis of nano-sized TiO{sub 2} anatase for large-area photon conversion

    Energy Technology Data Exchange (ETDEWEB)

    Babasaheb, Raghunath Sankapal; Shrikrishna, Dattatraya Sartale; Lux-Steiner, M.Ch.; Ennaoui, A. [Hahn-Meitner-Institut, Div. of Solar Energy Research, Berlin (Germany)

    2006-05-15

    We report on the synthesis of nanocrystalline titanium dioxide thin films and powders by chemical and electrochemical deposition methods. Both methods are simple, inexpensive and suitable for large-scale production. Air-annealing of the films and powders at T = 500 C leads to densely packed nanometer sized anatase TiO{sub 2} particles. The obtained layers are characterized by different methods such as: X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Titanium dioxide TiO{sub 2} (anatase) phase with (101) preferred orientation has been obtained for the films deposited on glass; indium doped tin oxide (ITO) and quartz substrates. The powder obtained as the byproduct consists of TiO{sub 2} with anatase-phase as well. (authors)

  5. Chemical and electrochemical synthesis of nano-sized TiO2 anatase for large-area photon conversion

    International Nuclear Information System (INIS)

    Babasaheb, Raghunath Sankapal; Shrikrishna, Dattatraya Sartale; Lux-Steiner, M.Ch.; Ennaoui, A.

    2006-01-01

    We report on the synthesis of nanocrystalline titanium dioxide thin films and powders by chemical and electrochemical deposition methods. Both methods are simple, inexpensive and suitable for large-scale production. Air-annealing of the films and powders at T = 500 C leads to densely packed nanometer sized anatase TiO 2 particles. The obtained layers are characterized by different methods such as: X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Titanium dioxide TiO 2 (anatase) phase with (101) preferred orientation has been obtained for the films deposited on glass; indium doped tin oxide (ITO) and quartz substrates. The powder obtained as the byproduct consists of TiO 2 with anatase-phase as well. (authors)

  6. Electrochemical synthesis and spectroscopic characterization of poly(N-phenylpyrrole coatings in an organic medium on iron and platinum electrodes

    Directory of Open Access Journals (Sweden)

    A.K.D. Diaw

    2008-12-01

    Full Text Available The electrochemical synthesis of poly(N-phenylpyrrole film was achieved on pretreated iron and platinum electrodes in acetonitrile solutions containing 0.1 M N-phenylpyrrole as the monomer and 0.1 M tetrabutylammonium trifluoromethane sulfonate (Bu4NCF3SO3 as the supporting-salt. The results showed that a surface treatment by 10 % aqueous nitric acid inhibits iron dissolution without preventing the N-phenylpyrrole oxidation. Very strongly adherent films were obtained at constant-potential, constant-current and cyclic voltammetry. XPS measurements, infrared (FT-IR and electronic absorption (UV-vis spectroscopies were used to characterize the iron and platinum-coated electrodes. Finally the anticorrosion properties of the PΦP film were evidenced.

  7. Low Temperature Synthesis, Chemical and Electrochemical Characterization of LiNi(x)Co(1-x)O2 (0 less than x less than 1)

    Science.gov (United States)

    Nanjundaswamy, K. S.; Standlee, D.; Kelly, C. O.; Whiteley, R. V., Jr.

    1997-01-01

    A new method of synthesis for the solid solution cathode materials LiNi(x)Co(1-x)O2 (0 less than x less than 1) involving enhanced reactions at temperatures less than or equal to 700 deg. C, between metal oxy-hydroxide precursors MOOH (M = Ni, Co) and Li-salts (Li2CO3, LiOH, and LiNO3) has been investigated. The effects of synthesis conditions and sources of Li, on phase purity, microstructure, and theoretical electrochemical capacity (total M(3+) content) are characterized by powder X-ray diffraction analysis, scanning electron microscopy, chemical analysis and room temperature magnetic susceptibility. An attempt has been made to correlate the electrochemical properties with the synthesis conditions and microstructure.

  8. In situ synthesis of N and Cu functionalized mesoporous FDU-14 resins and carbons for electrochemical hydrogen storage

    Energy Technology Data Exchange (ETDEWEB)

    Kong, AiGuo; Wang, WenJuan; Yang, Fan; Ding, HanMing; Shan, YongKui [Department of Chemistry, East China Normal University, ShangHai 200062 (China)

    2010-07-15

    N and Cu cooperatively functionalized mesoporous resin and carbon materials with bicontinuous cubic structure (FDU-14) were obtained by a novel synthesis method. In this method, block copolymers were used as the templates as well as the precursors for the preparation of these modifying mesoporous materials. The CuC{sub 2}O{sub 4} in the channels of mesoporous FDU-14 resins was gotten by in situ oxidation of the templates in a catalytic redox system containing Cu{sup 2+}, Al{sup 3+}, NO{sub 3}{sup -}, PO{sub 4}{sup 3-}, SO{sub 4}{sup 2-} ions. Simultaneously, the phenol-formaldehyde resin frameworks were in situ functionalized by the amine group resulting from the reduction of NO{sub 3}{sup -}, leading to the formation of N and CuC{sub 2}O{sub 4} modified mesoporous FDU-14 resin materials. Its pyrolysis at the different temperatures resulted in the production of N and Cu cooperatively functionalized mesoporous FDU-14 resin and carbon materials. The structure and composition of these materials were characterized by the X-ray power diffraction, transmission electron microscopy, N{sub 2} adsorption-desorption analysis, X-ray photoelectron spectroscopy, infrared spectroscopy, thermogravimetry analysis, and inductive coupled plasma emission spectroscopy. The electrochemical measurement indicated that N and Cu cooperatively functionalized mesoporous FDU-14 carbon materials possessed the enhanced electrochemical hydrogen storage performance. (author)

  9. Magnetic-field-assisted synthesis of Co{sub 3}O{sub 4} nanoneedles with superior electrochemical capacitance

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Tao; Xie, Yan; Zhang, Guoxiong; He, Zhenni; Lu, Yisheng; Guo, Haibo [Shanghai University, Department of Electronic Information Materials, School of Materials Science and Engineering (China); Lin, Chuan [GE Global Research, China Technology Center (China); Chen, Yigang, E-mail: yigangchen@shu.edu.cn [Shanghai University, Department of Electronic Information Materials, School of Materials Science and Engineering (China)

    2015-12-15

    Nanostructured Co{sub 3}O{sub 4} films have been deposited on nickel foam in a magnetic-field-assisted hydrothermal process followed by annealing in air. The magnetic field strength is varied to study its relationship with nanostructures, morphology, and electrochemical properties of the Co{sub 3}O{sub 4} electrodes. The Co{sub 3}O{sub 4} films synthesized in the weak magnetic fields consist of dispersed nanoneedles, which are different from clustered nanoneedles when the magnetic field is absent. Moreover, the magnetic fields (of several millitesla) induced substantial changes in the nanostructures and electrochemical properties of the Co{sub 3}O{sub 4} films. A possible formation mechanism of Co{sub 3}O{sub 4} nanoneedles is proposed by comparing the morphologies and nanostructures of the films synthesized with and without the magnetic fields. Among these electrodes, the optimal one has a high specific capacitance (970.8 F g{sup −1} at 0.5 A g{sup −1}), good power capability (847.5 F g{sup −1} at 6.0 A g{sup −1}), and an excellent retention ratio (93.7 % over 1000 cycles). All these impressive results demonstrate that magnetic fields may be an economic and effective tool in hydrothermal synthesis of Co{sub 3}O{sub 4} electrodes for high-performance supercapacitors.

  10. Facile synthesis of reduced graphene oxide nanosheets by a sodium diphenylamine sulfonate reduction process and its electrochemical property

    International Nuclear Information System (INIS)

    Ji, Yunzhou; Liu, Qi; Cheng, Meiling; Lai, Lifang; Li, Zhanfeng; Peng, Yuxin; Yang, Yong

    2013-01-01

    We report a new method to convert graphene oxide (GO) to stable colloidal dispersion of reduced graphene oxide nanosheets (RGONS) using sodium diphenylamine sulfonate (SDAS) as a reductant, as well as itself and its redox product as the stabilizer. The as-prepared RGONS have been characterized by X-ray diffraction, Fourier transform infrared spectroscopy, UV–visible spectroscopy, thermo-gravimetric analysis, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, atomic force microscopy and Raman spectroscopy. The results indicate that the bulk of oxygen-containing functional groups from GO have been removed. Based on the cyclic voltammogram (CV) analyses, it is found that the RGONS-based material exhibits better electrochemical activity in sensing ascorbic acid than GO. The simple method provides a new efficient route for the synthesis of water-soluble RGONS on a large scale and novel composites. - Highlights: • We report a new environment-friendly reductant for the reduction of graphene oxide. • The reduction process needn't use other stabilizer except for using reductant. • The reduced graphene oxide nanosheet (RGONS) aqueous dispersion is stable. • The RGONS shows a high electrochemical activity in sensing ascorbic acid

  11. Synthesis of binary bismuth-cadmium oxide nanorods with sensitive electrochemical sensing performance

    International Nuclear Information System (INIS)

    Wen, Yong; Pei, Lizhai; Wei, Tian

    2017-01-01

    Binary bismuth-cadmium oxide nanorods have been synthesized by a simple hydrothermal process without templates and additives. X-ray diffraction and high-resolution transmission electron microscopy reveal that the nanorods possess single crystalline tetragonal Bi 2 CdO 4 phase. Scanning electron microscopy and transmission electron microscopy images show that the length and diameter of the nanorods are 20-300 nm and 5-10 μm, respectively. The formation of the binary bismuth-cadmium oxide nanorods is closely related to the hydrothermal parameters. The electrochemical sensing performance of the binary bismuth-cadmium oxide nanorods has been investigated using the nanorods as glassy carbon electrode modifiers. The detection limit is 0.19 μM with a linear range of 0.0005-2 mM. The nanorod-modified glassy carbon electrode exhibits good electrocatalytic activity toward L-cysteine and great application potential for electrochemical sensors.

  12. Facile synthesis of polypyrrole nanofiber and its enhanced electrochemical performances in different electrolytes

    Directory of Open Access Journals (Sweden)

    C. K. Das

    2012-12-01

    Full Text Available A porous nanocomposite based on polypyrrole (PPy and sodium alginate (SA has been synthesized by easy, inexpensive, eco-friendly method. As prepared nanocomposite showed fibrillar morphology in transmission electron microscopic (TEM analysis. The average diameter of ~100 nm for the nanofibers was observed from scanning electron microscopic (SEM analysis. As prepared nanofiber, was investigated as an electrode material for supercapacitor application in different aqueous electrolyte solutions. PPy nanofiber showed enhanced electrochemical performances in 1M KCl solution as compared to 1M Na2SO4 solution. Maximum specific capacitance of 284 F/g was found for this composite in 1 M KCl electrolyte. It showed 76% specific capacitance retention after 600 cycles in 1 M KCl solution. Electrochemical Impedance Spectra showed moderate capacitive behavior of the composite in both the electrolytes. Further PPy nanofiber demonstrated higher thermal stability as compared to pure PPy.

  13. Synthesis of binary bismuth-cadmium oxide nanorods with sensitive electrochemical sensing performance

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Yong [Xinjiang Univ., Xinjiang (China). School of Civil Engineering and Architecture; Pei, Lizhai; Wei, Tian [Anhui Univ. of Technology, Anhui (China). School of Materials Science and Engineering

    2017-07-15

    Binary bismuth-cadmium oxide nanorods have been synthesized by a simple hydrothermal process without templates and additives. X-ray diffraction and high-resolution transmission electron microscopy reveal that the nanorods possess single crystalline tetragonal Bi{sub 2}CdO{sub 4} phase. Scanning electron microscopy and transmission electron microscopy images show that the length and diameter of the nanorods are 20-300 nm and 5-10 μm, respectively. The formation of the binary bismuth-cadmium oxide nanorods is closely related to the hydrothermal parameters. The electrochemical sensing performance of the binary bismuth-cadmium oxide nanorods has been investigated using the nanorods as glassy carbon electrode modifiers. The detection limit is 0.19 μM with a linear range of 0.0005-2 mM. The nanorod-modified glassy carbon electrode exhibits good electrocatalytic activity toward L-cysteine and great application potential for electrochemical sensors.

  14. Synthesis, spectroscopic characterization and pH dependent photometric and electrochemical fate of Schiff bases.

    Science.gov (United States)

    Rauf, Abdur; Shah, Afzal; Abbas, Saghir; Rana, Usman Ali; Khan, Salah Ud-Din; Ali, Saqib; Zia-Ur-Rehman; Qureshi, Rumana; Kraatz, Heinz-Bernhard; Belanger-Gariepy, Francine

    2015-03-05

    A new Schiff base, 1-((4-bromophenylimino) methyl) naphthalen-2-ol (BPIMN) was successfully synthesized and characterized by (1)H NMR, (13)C NMR, FTIR and UV-Vis spectroscopy. The results were compared with a structurally related Schiff base, 1-((4-chlorophenylimino) methyl) naphthalen-2-ol (CPIMN). The photometric and electrochemical fate of BPIMN and CPIMN was investigated in a wide pH range. The experimental findings were supported by quantum mechanical approach. The redox mechanistic pathways were proposed on the basis of results obtained electrochemical techniques. Moreover, pH dependent UV-Vis spectroscopy of BPIMN and CPIMN was carried out and the appearance of isosbestic points indicated the existence of these compounds in different tautomeric forms. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Synthesis of fully and partially sulfonated polyanilines derived from ortanilic acid: An electrochemical and electromicrogravimetric study

    International Nuclear Information System (INIS)

    Cano Marquez, Abraham Guadalupe; Torres Rodriguez, Luz Maria; Montes Rojas, Antonio

    2007-01-01

    The electrochemical polymerization of 2-aminobenzene sulfonic acid, also called ortanilic acid (o-ASA), on a gold electrode precoated with polyaniline (PANI), has been carried out. We proved that the electropolymerization of o-ASA is enhanced on PANI electrodes, resulting in thicker films obtained in aqueous media at room temperature. The electrosynthesized film (P(o-ASA)) was characterized by cyclic voltammetry, FTIR and nuclear magnetic resonance. The compensation of P(o-ASA) charge was evaluated using electrochemical quartz crystal microbalance combined with cyclic voltammetry, which showed that the electroneutralization process mainly involves cations. Additionally, copolymers of aniline and o-ASA were electrosynthesized, using a metallic electrode modified with PANI also as a working electrode. The degree of sulfanation of copolymers has been modulated with the proportions of monomers in the electrosynthesis solution. The studies reveal a more important participation of cations in fully sulfonated polyaniline than in partially sulfonated polyaniline

  16. Synthesis and electrochemical behavior of nanostructured cauliflower-shape Co-Ni/Co-Ni oxides composites

    International Nuclear Information System (INIS)

    Gupta, Vinay; Kawaguchi, Toshikazu; Miura, Norio

    2009-01-01

    Nanostructured Co-Ni/Co-Ni oxides were electrochemically deposited onto stainless steel electrode by electrochemical method and characterized for their structural and supercapacitive properties. The SEM images indicated that the obtained Co-Ni/Co-Ni oxides had cauliflower-type nanostructure. The X-ray diffraction pattern showed the formation of Co 3 O 4 , NiO, Co and Ni. The EDX elemental mapping images indicated that Ni, Co and O are distributed uniformly. The deposited Co-Ni/Co-Ni oxides showed good supercapacitive characteristics with a specific capacitance of 331 F/g at 1 mA/cm 2 current density in 1 M KOH electrolyte. A mechanism of the formation of cauliflower-shape Co-Ni/Co-Ni oxides was proposed. A variety of promising applications in the fields such as energy storage devices and sensors can be envisioned from Co-Ni/Co-Ni oxides

  17. Synthesis of Some Novel Pyrimidine Derivatives and Investigation of their Electrochemical Behavior

    International Nuclear Information System (INIS)

    Akbas, Esvet; Gumus, Selcuk; Sumer, Mehmet Rauf; Akyaz, Inci; Levent, Abdulkadir

    2010-01-01

    2-Iminopyrimidines (1a-e) and 2-thioxopyrimidine (2) were synthesized using the Biginelli three component cyclocondensation reaction of an appropriate β-diketone, arylaldehyde, and guanidine (for 1a-e) or thiourea (for 2). The electrochemical properties of the novel systems were investigated by CV and DPV. Moreover, B3LYP/6-31G(d,p) method was applied to the present structures in order to gather some structural and physicochemical data

  18. Synthesis of graphene nanomaterials and their application in electrochemical energy storage

    Science.gov (United States)

    Xiong, Guoping

    The need to store and use energy on diverse scales in a modern technological society necessitates the design of large and small energy systems, among which electrical energy storage systems such as batteries and capacitors have attracted much interest in the past several decades. Supercapacitors, also known as ultracapacitors, or electrochemical capacitors, with fast power delivery and long cycle life are complementing or even replacing batteries in many applications. The rapid development of miniaturized electronic devices has led to a growing need for rechargeable micro-power sources with high performance. Among different sources, electrochemical micro-capacitors or micro-supercapacitors provide higher power density than their counterparts and are gaining increased interest from the research and engineering communities. Rechargeable Li ion batteries with high energy and power density, long cycling life, high charge-discharge rate (1C - 3C) and safe operation are in high demand as power sources and power backup for hybrid electric vehicles and other applications. In the present work, graphene-based graphene materials have been designed and synthesized for electrochemical energy storage applications, e.g., conventional supercapacitors (macro-supercapacitors), microsupercapacitors and lithium ion batteries. Factors influencing the formation and structure of graphitic petals grown by microwave plasma-enhanced chemical vapor deposition on oxidized silicon substrates were investigated through process variation and materials analysis. Insights gained into the growth mechanism of these graphitic petals suggest a simple scribing method can be used to control both the location and formation of petals on flat Si substrates. Transitional metal oxides and conducting polymers have been coated on the graphitic petal-based electrodes by facile chemical methods for multifunctional energy storage applications. Detailed electrochemical characterization (e.g., cyclic voltammetry and

  19. Tricobalt tetroxide nanoplate arrays on flexible conductive fabric substrate: Facile synthesis and application for electrochemical supercapacitors

    Science.gov (United States)

    Nagaraju, Goli; Ko, Yeong Hwan; Yu, Jae Su

    2015-06-01

    Tricobalt tetroxide (Co3O4) nanoplate arrays (NPAs) were synthesized on flexible conductive fabric substrate (FCFs) by a facile two-electrode system based electrochemical deposition method, followed by a simple heat treatment process. Initially, cobalt hydroxide (Co(OH)2) NPAs were electrochemically deposited on FCFs by applying an external voltage of -1.5 V for 30 min. Then, the Co3O4 NPAs on FCFs was obtained by thermal treatment of as-deposited Co(OH)2 NPAs on FCFs at 200 °C for 2 h. From the analysis of morphological and crystal properties, the Co3O4 NPAs were well integrated and uniformly covered over the entire surface of substrate with good crystallinity in the cubic phase. Additionally, the fabricated sample was directly used as a binder-free electrode to examine the feasibility for electrochemical supercapacitors using cyclic voltammetry and galvanic charge-discharge measurements in 1 M KOH electrolyte solution. The Co3O4 NPAs coated FCFs electrode exhibited a maximum specific capacitance of 145.6 F/g at a current density of 1 A/g and an excellent rate capability after 1000 cycles at a current density of 3 A/g. This facile fabrication method for integrating the Co3O4 nanostructures on FCFs could be a promising approach for advanced flexible electronic and energy-storage device applications.

  20. Synthesis, spectroscopic and electrochemical performance of pasted β-nickel hydroxide electrode in alkaline electrolyte

    Science.gov (United States)

    Shruthi, B.; Bheema Raju, V.; Madhu, B. J.

    2015-01-01

    β-Nickel hydroxide (β-Ni(OH)2) was successfully synthesized using precipitation method. The structure and property of the β-Ni(OH)2 were characterized by X-ray diffraction (XRD), Fourier Transform infra-red (FT-IR), Raman spectra and thermal gravimetric-differential thermal analysis (TG-DTA). The results of the FTIR spectroscopy and TG-DTA studies indicate that the β-Ni(OH)2 contains water molecules and anions. The microstructural and composition studies have been performed using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX) analysis. A pasted-type electrode is prepared using β-Ni(OH)2 powder as the active material on a nickel sheet as a current collector. Cyclic voltammetry (CV) and Electrochemical impedance spectroscopy (EIS) studies were performed to evaluate the electrochemical performance of the β-Ni(OH)2 electrode in 6 M KOH electrolyte. CV curves showed a pair of strong redox peaks as a result of the Faradaic redox reactions of β-Ni(OH)2. The proton diffusion coefficient (D) for the present β-Ni(OH)2 electrode material is found to be 1.44 × 10-12 cm2 s-1. Further, electrochemical impedance studies confirmed that the β-Ni(OH)2 electrode reaction processes are diffusion controlled.

  1. EDTA assisted synthesis of hydroxyapatite nanoparticles for electrochemical sensing of uric acid

    Energy Technology Data Exchange (ETDEWEB)

    Kanchana, P.; Sekar, C., E-mail: Sekar2025@gmail.com

    2014-09-01

    Hydroxyapatite nanoparticles have been synthesized using EDTA as organic modifier by a simple microwave irradiation method and its application for the selective determination of uric acid (UA) has been demonstrated. Electrochemical behavior of uric acid at HA nanoparticle modified glassy carbon electrode (E-HA/GCE) has been investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), linear sweep voltammetry (LSV) and amperometry. The E-HA modified electrode exhibits efficient electrochemical activity towards uric acid sensing without requiring enzyme or electron mediator. Amperometry studies revealed that the fabricated electrode has excellent sensitivity for uric acid with the lowest detection limit of 142 nM over a wide concentration range from 1 × 10{sup −7} to 3 × 10{sup −5} M. Moreover, the studied E-HA modified GC electrode exhibits a good reproducibility and long-term stability and an admirable selectivity towards the determination of UA even in the presence of potential interferents. The analytical performance of this sensor was evaluated for the detection of uric acid in human urine and blood serum samples. - Highlights: • EDTA- hydroxyapatite (HA) nanoparticles have been synthesized by microwave irradiation method. • A novel amperometric Uric Acid biosensor has been fabricated using E-HA/GCE. • The fabricated sensor exhibits a wide linear range, good stability and high reproducibility. • The sensor was applied for the detection of UA in human blood serum and urine.

  2. EDTA assisted synthesis of hydroxyapatite nanoparticles for electrochemical sensing of uric acid

    International Nuclear Information System (INIS)

    Kanchana, P.; Sekar, C.

    2014-01-01

    Hydroxyapatite nanoparticles have been synthesized using EDTA as organic modifier by a simple microwave irradiation method and its application for the selective determination of uric acid (UA) has been demonstrated. Electrochemical behavior of uric acid at HA nanoparticle modified glassy carbon electrode (E-HA/GCE) has been investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), linear sweep voltammetry (LSV) and amperometry. The E-HA modified electrode exhibits efficient electrochemical activity towards uric acid sensing without requiring enzyme or electron mediator. Amperometry studies revealed that the fabricated electrode has excellent sensitivity for uric acid with the lowest detection limit of 142 nM over a wide concentration range from 1 × 10 −7 to 3 × 10 −5 M. Moreover, the studied E-HA modified GC electrode exhibits a good reproducibility and long-term stability and an admirable selectivity towards the determination of UA even in the presence of potential interferents. The analytical performance of this sensor was evaluated for the detection of uric acid in human urine and blood serum samples. - Highlights: • EDTA- hydroxyapatite (HA) nanoparticles have been synthesized by microwave irradiation method. • A novel amperometric Uric Acid biosensor has been fabricated using E-HA/GCE. • The fabricated sensor exhibits a wide linear range, good stability and high reproducibility. • The sensor was applied for the detection of UA in human blood serum and urine

  3. EDTA assisted synthesis of hydroxyapatite nanoparticles for electrochemical sensing of uric acid.

    Science.gov (United States)

    Kanchana, P; Sekar, C

    2014-09-01

    Hydroxyapatite nanoparticles have been synthesized using EDTA as organic modifier by a simple microwave irradiation method and its application for the selective determination of uric acid (UA) has been demonstrated. Electrochemical behavior of uric acid at HA nanoparticle modified glassy carbon electrode (E-HA/GCE) has been investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), linear sweep voltammetry (LSV) and amperometry. The E-HA modified electrode exhibits efficient electrochemical activity towards uric acid sensing without requiring enzyme or electron mediator. Amperometry studies revealed that the fabricated electrode has excellent sensitivity for uric acid with the lowest detection limit of 142 nM over a wide concentration range from 1 × 10(-7) to 3 × 10(-5)M. Moreover, the studied E-HA modified GC electrode exhibits a good reproducibility and long-term stability and an admirable selectivity towards the determination of UA even in the presence of potential interferents. The analytical performance of this sensor was evaluated for the detection of uric acid in human urine and blood serum samples. Copyright © 2014. Published by Elsevier B.V.

  4. Electrochemical Synthesis of Nitro-Chitosan and Its Performance in Chromium Removal

    Directory of Open Access Journals (Sweden)

    Scott M. McLennan

    2013-07-01

    Full Text Available A synthesized polymeric form of chitosan, electrochemically precipitated and photochemically modified, has been found to have significant value in removal of toxic chromate oxyanions from solution. Fourier Transform Infra-Red (FTIR, Raman and X-ray photoelectron spectroscopy (XPS indicated that a significant percentage of the amine functional groups were oxidized to nitro groups as a result of reactions with hydroxyl ions formed in the electrochemical process with additional oxidation occurring as a result of exposure to ultra-violet light. The adsorption capacity of the modified chitosan for chromate was investigated in a batch system by taking into account effects of initial concentration, pH of the solution and contact time. Nitro-chitosan showed greater adsorption capacity towards Cr (VI than other forms of chitosan, with a maximum adsorption of 173 mg/g. It was found that pH 3 is the optimum for adsorption, a Langmuir model is the best fit for the adsorption isotherm, and the kinetics of reaction followed a pseudo second order function. Overall, our results indicate that electrochemical modification of chitosan is an effective method to enhance the reactivity of chitosan towards metals.

  5. Synthesis and electrochemical properties of MnO2 nanorods/graphene composites for supercapacitor applications

    International Nuclear Information System (INIS)

    Deng, SiXu; Sun, Dan; Wu, ChunHui; Wang, Hao; Liu, JingBing; Sun, YuXiu; Yan, Hui

    2013-01-01

    MnO 2 nanorods/graphene composite materials have been fabricated using a facile hydrothermal method for supercapacitor applications. The prepared composite materials are characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and transmission electron microscope (TEM). Electrochemical performances are evaluated using cyclic voltammetry (CV), galvanostatic charge–discharge and electrochemical impedance spectrometry (EIS). It indicates that ratio of MnO 2 nanorods to graphene in composite materials has significant influence on the electrochemical performance of composite electrodes. We have achieved the maximum specific capacitance of 218 F g −1 at the scan rate of 5 mV s −1 in 1 M Na 2 SO 4 aqueous solution. Additionally, MnO 2 nanorods/graphene composite materials exhibit highest energy density of 16 Wh kg −1 at power density of 95 W kg −1 and excellent capacitance retention with no more than 6% capacitance loss after 1000 cycles at the most favorable composites ratio

  6. Estrone specific molecularly imprinted polymeric nanospheres: synthesis, characterization and applications for electrochemical sensor development.

    Science.gov (United States)

    Congur, Gulsah; Senay, Hilal; Turkcan, Ceren; Canavar, Ece; Erdem, Arzum; Akgol, Sinan

    2013-06-28

    The aim of this study is (i) to prepare estrone-imprinted nanospheres (nano-EST-MIPs) and (ii) to integrate them into the electrochemical sensor as a recognition layer. N-methacryloyl-(l)-phenylalanine (MAPA) was chosen as the complexing monomer. Firstly, estrone (EST) was complexed with MAPA and the EST-imprinted poly(2-hyroxyethylmethacrylate-co-N-methacryloyl-(l)-phenylalanine) [EST-imprinted poly(HEMA-MAPA)] nanospheres were synthesized by surfactant- free emulsion polymerization method. The specific surface area of the EST-imprinted poly(HEMA-MAPA) nanospheres was found to be 1275 m2/g with a size of 163.2 nm in diameter. According to the elemental analysis results, the nanospheres contained 95.3 mmole MAPA/g nanosphere. The application of EST specific MIP nanospheres for the development of an electrochemical biosensor was introduced for the first time in our study by using electrochemical impedance spectroscopy (EIS) technique. This nano-MIP based sensor presented a great specificity and selectivity for EST.

  7. Synthesis and electrochemical analysis of AlVMoO7 oxide prepared ...

    Indian Academy of Sciences (India)

    2018-05-16

    May 16, 2018 ... solid solution and two-phase regimes. In the voltage ... LiMn2O4) [1]. Among these compounds, olivine LiFePO4, ... polyanions provide numerous metal oxidation states, struc- tural stability ... 2.1a Sol–gel synthesis (SG): In SG synthesis method, ... AlVMoO7 and confirms that only a single phase is formed.

  8. Hydrothermal synthesis and electrochemical characterization of VO2 (B) with controlled crystal structures

    International Nuclear Information System (INIS)

    Jiang Wentao; Ni Juan; Yu Ke; Zhu Ziqiang

    2011-01-01

    Three different VO 2 (B) nanostructures, including urchin-like VO 2 (B), VO 2 (B) honeycombs and VO 2 (B) nanorods have been successfully fabricated through hydrothermal process by adjusting the concentrations of the oxalic acid. The microstructure and morphology of the VO 2 nanostructures were evaluated by using X-ray diffraction and scanning and transmission electron microscopies. Electrochemical properties measurements of urchin-like VO 2 (B) and VO 2 (B) honeycombs showed excellent cycling performance, especially the urchin-like VO 2 (B) exhibited higher discharge capacity and better capacity retention.

  9. Facile synthesis and photo electrochemical performance of SnSe thin films

    Science.gov (United States)

    Pusawale, S. N.; Jadhav, P. S.; Lokhande, C. D.

    2018-05-01

    Orthorhombic structured SnSe thin films are synthesized via SILAR (successive ionic layer adsorption and reaction) method on glass substrates. The structural properties of thin films are characterized by x-ray diffraction, scanning electron microscopy studies from which nanoparticles with an elongated shape and hydrophilic behavior are observed. UV -VIS absorption spectroscopy study showed the maximum absorption in the visible region with a direct band gap of 1.55 eV. The photo electrochemical study showed p-type electrical conductivity.

  10. Synthesis and Microstructural Characterization of Manganese Oxide Electrodes for Application as Electrochemical Supercapacitors

    Science.gov (United States)

    Babakhani, Banafsheh

    The aim of this thesis work was to synthesize Mn-based oxide electrodes with high surface area structures by anodic electrodeposition for application as electrochemical capacitors. Rod-like structures provide large surface areas leading to high specific capacitances. Since templated electrosynthesis of rods is not easy to use in practical applications, it is more desirable to form rod-like structures without using any templates. In this work, Mn oxide electrodes with rod-like structures (˜1.5 µm in diameter) were synthesized from a solution of 0.01 M Mn acetate under galvanostatic control without any templates, on Au coated Si substrates. The electrochemical properties of the synthesized nanocrystalline electrodes were investigated to determine the effect of morphology, chemistry and crystal structure on the corresponding electrochemical behavior of Mn oxide electrodes. Mn oxides prepared at different current densities showed a defective antifluoritetype crystal structure. The rod-like Mn oxide electrodes synthesized at low current densities (5 mAcm.2) exhibited a high specific capacitance due to their large surface areas. Also, specific capacity retention after 250 cycles in an aqueous solution of 0.5 M Na2SO4 at 100 mVs -1 was about 78% of the initial capacity (203 Fg-1 ). To improve the electrochemical capacitive behavior of Mn oxide electrodes, a sequential approach and a one-step method were adopted to synthesize Mn oxide/PEDOT electrodes through anodic deposition on Au coated Si substrates from aqueous solutions. In the former case, free standing Mn oxide rods (about 10 µm long and less than 1.5 µm in diameter) were first synthesized, then coated by electro-polymerization of a conducting polymer (PEDOT) giving coaxial rods. The one-step, co-electrodeposition method produced agglomerated Mn oxide/PEDOT particles. The electrochemical behavior of the deposits depended on the morphology and crystal structure of the fabricated electrodes, which were affected

  11. Hydrothermal Synthesis and Electrochemical Performance of Manganese Oxide (Na-OMS-2) Nanorods.

    Science.gov (United States)

    Zhang, Qing; Xu, Shan; Zheng, Hao; Luo, Zhaohui; Liu, Kang; Wang, Wei; Li, Guohua; Wang, Shiquan; Liu, Jianwen; Feng, Chuanqi

    2017-02-01

    Sodium octahedral molecular sieve nanorods (Na-OMS-2) were prepared through a facile hydrothermal method. The effects of reaction temperature and duration on particle sizes of the products were investigated. The electrochemical performance of samples was studied by constant current charge–discharge tests as cathode material for Li-ion batteries (LIBs). The initial discharge capacity of Na-OMS-2 is 123.4 mAh g−1 and the capacity retention was 123.9 mAh g−1 after 100 cycles. The result demonstrates that Na-OMS-2 cathode material behaves a good cycling stability.

  12. On the mechanism of electrochemical ammonia synthesis on the Ru catalyst.

    Science.gov (United States)

    Back, Seoin; Jung, Yousung

    2016-04-07

    We theoretically investigate the electrochemical N2 reduction reaction (NRR) mechanism to produce NH3 on the Ru catalyst. All possible N-N dissociation steps during the reduction processes were evaluated along with the conventional associative and dissociative pathways. Based on the calculated free energy diagrams, it is revealed that the kinetically facile intermediate dissociative pathways during the NRR require a thermodynamic limiting potential (-0.71 V) similar to the associative pathway (-0.68 V), although the initial dissociative pathway as in the Haber-Bosch process has a substantial kinetic barrier for the N-N bond dissociation. The competitive hydrogen evolution is found to be a major hurdle for achieving a high efficiency for the electrochemical nitrogen reduction. In the low overpotential region, the hydrogen adsorption is thermodynamically more favorable than the protonation of N2, thereby reducing the number of active sites for the N2 activation. A comparison of free energies in the presence of different H-coverages on the Ru further demonstrates that the H-coverage can significantly increase the energy barrier for the first protonation of N2, resulting in a change of the potential determining step and an increase in the overpotentials.

  13. Electrochemical Synthesis of Mesoporous CoPt Nanowires for Methanol Oxidation

    Directory of Open Access Journals (Sweden)

    Albert Serrà

    2014-03-01

    Full Text Available A new electrochemical method to synthesize mesoporous nanowires of alloys has been developed. Electrochemical deposition in ionic liquid-in-water (IL/W microemulsion has been successful to grow mesoporous CoPt nanowires in the interior of polycarbonate membranes. The viscosity of the medium was high, but it did not avoid the entrance of the microemulsion in the interior of the membrane’s channels. The structure of the IL/W microemulsions, with droplets of ionic liquid (4 nm average diameter dispersed in CoPt aqueous solution, defined the structure of the nanowires, with pores of a few nanometers, because CoPt alloy deposited only from the aqueous component of the microemulsion. The electrodeposition in IL/W microemulsion allows obtaining mesoporous structures in which the small pores must correspond to the size of the droplets of the electrolytic aqueous component of the microemulsion. The IL main phase is like a template for the confined electrodeposition. The comparison of the electrocatalytic behaviours towards methanol oxidation of mesoporous and compact CoPt nanowires of the same composition, demonstrated the porosity of the material. For the same material mass, the CoPt mesoporous nanowires present a surface area 16 times greater than compact ones, and comparable to that observed for commercial carbon-supported platinum nanoparticles.

  14. Synthesis and photo-electrochemical properties of spinel-ferrite-coated hematite for solar water splitting

    Science.gov (United States)

    Selvaraj, Seenivasan; Moon, Hee; Kim, Do-Heyoung

    2018-01-01

    Photo-electrochemical water splitting with hematite photo-anodes under solar irradiation has attracted considerable attention as regards the production of renewable hydrogen energy. However, many challenges remain unresolved, as the full contribution of the catalytic over-layers has not been fully realized. Herein, we incorporate uniform spinel nickel-ferrite over-layers in hematite photo-anodes to obtain an improved understanding of the associated intrinsic changes. We achieve a 1.5-mA/cm2 photo-current density at 1.23 VRHE (RHE: reversible hydrogen electrode) under one-sun illumination conditions, along with a negative shift of 200 mV in the onset potential, for NiFe2O4-coated Sn-doped hematite photo-anodes. Fundamental electrochemical analyses clearly show that the shift in the onset potential is predominantly due to the enhanced photo-voltage development inside the hematite, rather than being purely caused by the interfacial kinetics. These insights reveal a new direction for fundamental research on photo-anodes towards fabrication of more efficient photo-anode systems.

  15. Novel polymeric potassium complex: Its synthesis, structural characterization, photoluminescence and electrochemical properties

    Energy Technology Data Exchange (ETDEWEB)

    Ceyhan, Goekhan [Chemistry Department, K.Maras Suetcue Imam University, 46100 K.Maras (Turkey); Tuemer, Mehmet, E-mail: mtumer@ksu.edu.tr [Chemistry Department, K.Maras Suetcue Imam University, 46100 K.Maras (Turkey); Koese, Muhammet; McKee, Vickie [Chemistry Department, Loughborough University, LE11 3TU Leicestershire (United Kingdom)

    2012-03-15

    In this paper, we obtained a novel poly(vanillinato potassium) complex (PVP) as a single crystal and characterized by analytical and spectroscopic methods. A single crystal of the PVP was obtained from the acetone solution. X-ray structural data show that crystals contain polymeric K{sup +} complex of vanillin. Each potassium ion in the polymeric structure is identical and seven-coordinate, bonded to two methoxy, two phenoxy and three aldehyde oxygen atoms from four vaniline molecules. Two aldehyde oxygen atoms are bridging between potassium ions. It crystallizes in the monoclinic system, space group P2{sub 1}/c, with lattice parameters a=9.6215(10) A, b=17.4139(19) A, c=9.6119(10) A, {beta}=100.457(2) Degree-Sign and Z=4. Thermal properties of the PVP were investigated by TGA, DTA and DSC methods. The electrochemical properties of the complex were studied in different solvents and at various scan rates. The luminescence properties of the complex in different solvents and at different pH values have been investigated. The results show that the complex exhibits more efficient luminescence property in CH{sub 3}CN and n-butanol. - Highlights: Black-Right-Pointing-Pointer Novel polymeric potassium complex was prepared and fully characterized. Black-Right-Pointing-Pointer X-ray crystal structure of complex was reported. Black-Right-Pointing-Pointer Electrochemical properties of compound were investigated. Black-Right-Pointing-Pointer Thermal and DSC measurements of complex were examined.

  16. Synthesis and electrochemical performance of polyaniline-MnO2 nanowire composites for supercapacitors

    Science.gov (United States)

    Chen, Ling; Song, Zhaoxia; Liu, Guichang; Qiu, Jieshan; Yu, Chang; Qin, Jiwei; Ma, Lin; Tian, Fengqin; Liu, Wei

    2013-02-01

    Polyaniline-MnO2 nanowire (PANI-MNW) composites were prepared by in situ chemical oxidative polymerization of aniline monomer in a suspension of MnO2 nanowires. The structure and morphology of the PANI-MNW composites were characterized by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). Their electrochemical properties were investigated using cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy in 1 mol/L KOH electrolyte. The PANI-MNW composites show significantly better specific capacity and redox performance in comparison to the untreated MnO2 nanowires. The enhanced properties can be mainly attributed to the composite structure wherein high porosity is created between MnO2 nanowires and PANI during the process of fabricating the PANI-MNW nanocomposites. A specific capacitance as high as 256 F/g is obtained at a current density of 1 A/g for PANI-MNW-5, and the composite also shows a good cyclic performance and coulomb efficiency.

  17. Hydrothermal synthesis of flower-like MoS2 nanospheres for electrochemical supercapacitors.

    Science.gov (United States)

    Zhou, Xiaoping; Xu, Bin; Lin, Zhengfeng; Shu, Dong; Ma, Lin

    2014-09-01

    Flower-like MoS2 nanospheres were synthesized by a hydrothermal route. The structure and surface morphology of the as-prepared MoS2 was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The supercapacitive behavior of MoS2 in 1 M KCl electrolyte was studied by means of cyclic voltammetry (CV), constant current charge-discharge cycling (CD) and electrochemical impedance spectroscopy (EIS). The XRD results indicate that the as-prepared MoS2 has good crystallinity. SEM images show that the MoS2 nanospheres have uniform sizes with mean diameter about 300 nm. Many nanosheets growing on the surface make the MoS2 nanospheres to be a flower-like structure. The specific capacitance of MoS2 is 122 F x g(-1) at 1 A x g(-1) or 114 F x g(-1) at 2 mv s(-1). All the experimental results indicate that MoS2 is a promising electrode material for electrochemical supercapacitors.

  18. Microwave synthesis and electrochemical properties of lithium manganese borate as cathode for lithium ion batteries

    Science.gov (United States)

    Ma, Ting; Muslim, Arzugul; Su, Zhi

    2015-05-01

    Nano structured LiMnBO3/C cathode materials are synthesized by a fast microwave solid-state reaction method using MnCO3, Li2CO3, H3BO3 and glucose as starting materials for the first time. The crystal structure, morphology and electrochemical properties of LiMnBO3/C composites are characterized by X-ray diffraction (XRD), raman spectroscopy (Ramon), scanning electron microscopy (SEM), transmission electron microscopy (TEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and charge-discharge tests. The result shows that not only monoclinic LiMnBO3/C but also hexagonal LiMnBO3/C cathode materials can be successfully synthesized by microwave solid-state method with power of 240 W in different time. Compared with h-LiMnBO3/C and mixed phase LiMnBO3/C, m-LiMnBO3/C displays lower charge-transfer resistance and the Warburg impedance, so it reveals a higher first discharge capacity of 156.3 mAh g-1 at 0.05 C within 1.8V-4.6 V, The value increases up to 173.2 mAh g-1 caused by the activation process. Even after 50 cycles, the discharge capacity of m-LiMnBO3/C still remains at 148.2 mAh g-1.

  19. Synthesis of Biokerosene through Electrochemical Hydrogenation of Terpene Hydrocarbons from Turpentine Oil

    Directory of Open Access Journals (Sweden)

    Tedi Hudaya

    2016-12-01

    Full Text Available Indonesia possesses great potential for developing renewable resources as alternative fuels. For example, turpentine oil obtained from Pinus merkusii, which contains mostly monoterpene hydrocarbons (C10H16. The oil is highly suitable to be processed for biokerosene or even jet biofuel. It consists of hydrocarbons within the range of C10 to C15. However, it contains insufficient H and thus needs to be upgraded. In the present work, electrochemical hydrogenation was used for upgrading. In the electrochemical cell, stainless steel, silver, and carbon were used alternately for the anode, while copper and silver Raschig rings were used for the cathode. An electrolyte solution of cuprous ammonium formate was utilized not only as a source of H but also to draw the unsaturated hydrocarbons into the aqueous phase. The electrolyte : oil ratio (up to 2:1, electrolyte concentration (between 0.4 and 2 M and reaction time were varied throughout the experiments. The bromine number (unsaturation level of the turpentine oil, which was initially 1,86 (mole Br2/mole, was lowered significantly to 0.69-0.90. Promising increase of smoke point values were observed from 11 mm to 16-24 mm, indicating a higher H content of the processed oil, thus making it suitable as a substitute for petroleum kerosene.

  20. Microwave synthesis of copper network onto lithium iron phosphate cathode materials for improved electrochemical performance

    Energy Technology Data Exchange (ETDEWEB)

    Hsieh, Chien-Te, E-mail: cthsieh@saturn.yzu.edu.tw [Department of Chemical Engineering and Materials Science, Yuan Ze University, Taoyuan 320, Taiwan (China); Liu, Juan-Ru [Department of Chemical Engineering and Materials Science, Yuan Ze University, Taoyuan 320, Taiwan (China); Juang, Ruey-Shin [Department of Chemical and Materials Engineering, Chang Gung University, Taoyuan 333, Taiwan (China); Lee, Cheng-En; Chen, Yu-Fu [Department of Chemical Engineering and Materials Science, Yuan Ze University, Taoyuan 320, Taiwan (China)

    2015-03-01

    Herein reported is an efficient microwave-assisted (MA) approach for growing Cu network onto LiFePO{sub 4} (LFP) powders as cathode materials for high-performance Li-ion batteries. The MA approach is capable of depositing highly-porous Cu network, fully covered the LFP powders. The electrochemical performance of Cu-coated LFP cathodes are well characterized by charge/discharge cycling and electrochemical impedance spectroscopy (EIS). The Cu network acts as the key role in improving the specific capacity, rate capability, electrode polarization, as compared to fresh LFP cathode without the Cu coating. The EIS incorporated with equivalent circuit reveals that the completed Cu network obviously suppresses the charge transfer resistance. This result can be attributed to the fact that the Cu network ensures the LFP crystals to get electron easily, alleviating the electrode polarization in view of one-dimensional Li{sup +} ion mobility in the olivine crystals. Based on the analysis of Randles plots, the relatively higher Li{sup +} diffusion coefficient reflects the more efficient Li{sup +} pathway in the LFP powders through the aid of porous Cu network. - Highlights: • An efficient route was used to prepare Cu/LiFePO{sub 4} (LFP) hybrid as cathode material. • The Cu/LFP cathodes exhibit an improved performance as compared to fresh LFP one. • The microwave approach can deposit Cu network, fully covered the LFP powders. • The Cu network ensures LFP to get electrons, alleviating electrode polarization.

  1. Synthesis of polyaniline/SnO2 nanocomposite and its improved electrochemical performance

    International Nuclear Information System (INIS)

    Luo, Zhenyu; Zhu, Yinhai; Liu, Enhui; Hu, Tiantian; Li, Zengpeng; Liu, Tiantian; Song, Longchu

    2014-01-01

    Highlights: • Supercapacitors based on PANI/SnO 2 nanocomposite were reported. • Supercapacitors using this material gave a specific capacitance of 501 F g −1 . • Capacitance retention was 85.8% over 2000 charge–discharge cycles. - Abstract: SnO 2 was prepared by the hydrothermal route. Aniline monomer was polymerized in the suspension of SnO 2 to form inorganic–organic nanocomposite materials, in which SnO 2 particles were embedded within polyaniline (PANI). Morphological and structural characterizations of the prepared samples were carried out using scanning electron microscope; transmission electron microscope; power X-ray diffraction and Fourier transform infrared spectroscopy. Their electrochemical properties were also investigated using cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy. The as-prepared nanocomposites had excellent properties in the capacitance, and its specific capacitance was up to 501 F g −1 with a specific energy density of 66.8 W h kg −1 at a power density of 960.6 W kg −1 . The device fulfilled the requirement of long durability necessary for an energy storage system, since after 2000 galvanostatic charge–discharge cycles, retention of 85.8% in capacitance was observed. These results indicated that the PANI/SnO 2 had a synergistic effect of the complementary properties of both components

  2. Controllable synthesis of hierarchical nickel cobalt sulfide with enhanced electrochemical activity

    Science.gov (United States)

    Tie, Jinjin; Han, Jiaxi; Diao, Guiqiang; Liu, Jiwen; Xie, Zhuopeng; Cheng, Gao; Sun, Ming; Yu, Lin

    2018-03-01

    The composition of nickel cobalt sulfide has great influence on its electrochemical performance. Herein, the nickel cobalt sulfide with different composition and mixed phase were synthesized by one-step solvothermal method through changing the molar ratio of Ni to Co in the reaction system. The electrochemical measurements showed that the nickel cobalt sulfide with a theoretical molar ratio of Ni/Co to be 1.5:1.5 (NCS-2) demonstrates the superior pseudocapacitive performance with a high specific capacitance (6.47 F cm-2 at 10 mA cm-2) and a favorable Coulombic efficiency (∼99%). Whereas, when applied as the catalyst for hydrogen evolution reaction in 1 M KOH aqueous electrolyte, the nickel cobalt sulfide with a theoretical molar ratio of Ni/Co is 1:2 (NCS-1) displays better catalytic activity, and it requires a relatively lower overpotential of 282 mV to deliver the current density of 10 mA cm-2.

  3. One-pot synthesis and electrochemical reactivity of carbon coated LiFePO4 spindles

    International Nuclear Information System (INIS)

    Yu Juanjuan; Hu Juncheng; Li Jinlin

    2012-01-01

    Highlights: ► Carbon coated LiFePO 4 spindles have been successfully synthesized via a novel supercritical method. ► The concentrations of lithium have an effect on the morphology of carbon coated LiFePO 4 . ► Amorphous carbon layer formed on the surface of LiFePO 4 by adding glucose. ► The carbon coating is responsible for the enhanced electrochemical performance. - Abstract: Spindle-like carbon coated LiFePO 4 (LiFePO 4 /C) composites have been successfully synthesized via a novel one-pot supercritical methanol method. The products were characterized by X-ray power diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA). The particle size, morphology and electrochemical reactivity changed with the concentration of lithium and carbon source. A possible morphology evolution process was also proposed. The glucose not only facilitates the formation of single crystalline LiFePO 4 , but also gives an amorphous carbon layer on the surface LiFePO 4 spindles.

  4. Carbonization-dependent nitrogen-doped hollow porous carbon nanospheres synthesis and electrochemical study for supercapacitors

    Science.gov (United States)

    Zhou, Lingyun; Xie, Guohong; Chen, Xiling

    2018-05-01

    In this paper, a nitrogen-doped hollow microporous carbon nanospheres was synthesized via the combination of hyper-crosslinking mediated self-assembly and further pyrolysis using polylactide-b-polystyrene (PLA-b-PS) copolymers and aniline monomers as precursor. The pore structure and the correlative electrochemical performance of nitrogen-doped hollow microporous carbon nanospheres were affected by the molar mass ratio of aniline and PS in block copolymers and the carbonization conditions. The electrochemical measurements results showed that the obtained PLA150-PS250-N4-900-10H sample with nitrogen content of 3.57% and the BET surface area of 945 m2 g-1 displays the best capacitance performance. At a current density of 1.0 Ag-1, the resultant specific capacitance is 250 Fg-1. In addition, it also exhibits high capacitance retention of 98% after charging-discharging 1500 times at 25 Ag-1. The results demonstrate the nitrogen-doped hollow microporous carbon nanospheres can be used as promising supercapacitor electrode materials for high performance energy storage devices.

  5. Hydrothermal-reduction synthesis of manganese oxide nanomaterials for electrochemical supercapacitors.

    Science.gov (United States)

    Zhang, Xiong; Chen, Yao; Yu, Peng; Ma, Yanwei

    2010-11-01

    In the present work, amorphous manganese oxide nanomaterials have been synthesized by a common hydrothermal method based on the redox reaction between MnO4(-) and Fe(2+) under an acidic condition. The synthesized MnO2 samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and electrochemical studies. XRD results showed that amorphous manganese oxide phase was obtained. XPS quantitative analysis revealed that the atomic ratio of Mn to Fe was 3.5 in the MnO2 samples. TEM images showed the porous structure of the samples. Electrochemical properties of the MnO2 electrodes were studied using cyclic voltammetry and galvanostatic charge-discharge cycling in 1 M Na2SO4 aqueous electrolyte, which showed excellent pseudocapacitance properties. A specific capacitance of 192 Fg(-1) at a current density of 0.5 Ag(-1) was obtained at the potential window from -0.1 to 0.9 V (vs. SCE).

  6. Facile solvothermal synthesis of a graphene nanosheet-bismuth oxide composite and its electrochemical characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Wang Huanwen [Key Laboratory of Eco-Environment-Related Polymer Materials of Ministry of Education, Key Laboratory of Polymer Materials of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China); Hu Zhongai, E-mail: zhongai@nwnu.edu.c [Key Laboratory of Eco-Environment-Related Polymer Materials of Ministry of Education, Key Laboratory of Polymer Materials of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China); Chang Yanqin; Chen Yanli; Lei Ziqiang; Zhang Ziyu; Yang Yuying [Key Laboratory of Eco-Environment-Related Polymer Materials of Ministry of Education, Key Laboratory of Polymer Materials of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China)

    2010-12-01

    This work demonstrates a novel and facile route for preparing graphene-based composites comprising of metal oxide nanoparticles and graphene. A graphene nanosheet-bismuth oxide composite as electrode materials of supercapacitors was firstly synthesized by thermally treating the graphene-bismuth composite, which was obtained through simultaneous solvothermal reduction of the colloidal dispersions of negatively charged graphene oxide sheets in N,N-dimethyl formamide (DMF) solution of bismuth cations at 180 {sup o}C. The morphology, composition, and microstructure of the composites together with pure graphite oxide, and graphene were characterized using powder X-ray diffraction (XRD), FT-IR, field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), thermogravimetry and differential thermogravimetry (TG-DTG). The electrochemical behaviors were measured by cyclic voltammogram (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS). The specific capacitance of 255 F g{sup -1} (based on composite) is obtained at a specific current of 1 A g{sup -1} as compared with 71 F g{sup -1} for pure graphene. The loaded-bismuth oxide achieves a specific capacitance as high as 757 F g{sup -1} even at 10 A g{sup -1}. In addition, the graphene nanosheet-bismuth oxide composite electrode exhibits the excellent rate capability and well reversibility.

  7. Facile solvothermal synthesis of a graphene nanosheet-bismuth oxide composite and its electrochemical characteristics

    International Nuclear Information System (INIS)

    Wang Huanwen; Hu Zhongai; Chang Yanqin; Chen Yanli; Lei Ziqiang; Zhang Ziyu; Yang Yuying

    2010-01-01

    This work demonstrates a novel and facile route for preparing graphene-based composites comprising of metal oxide nanoparticles and graphene. A graphene nanosheet-bismuth oxide composite as electrode materials of supercapacitors was firstly synthesized by thermally treating the graphene-bismuth composite, which was obtained through simultaneous solvothermal reduction of the colloidal dispersions of negatively charged graphene oxide sheets in N,N-dimethyl formamide (DMF) solution of bismuth cations at 180 o C. The morphology, composition, and microstructure of the composites together with pure graphite oxide, and graphene were characterized using powder X-ray diffraction (XRD), FT-IR, field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), thermogravimetry and differential thermogravimetry (TG-DTG). The electrochemical behaviors were measured by cyclic voltammogram (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS). The specific capacitance of 255 F g -1 (based on composite) is obtained at a specific current of 1 A g -1 as compared with 71 F g -1 for pure graphene. The loaded-bismuth oxide achieves a specific capacitance as high as 757 F g -1 even at 10 A g -1 . In addition, the graphene nanosheet-bismuth oxide composite electrode exhibits the excellent rate capability and well reversibility.

  8. Synthesis and electrochemical evaluation of an amorphous titanium dioxide derived from a solid state precursor

    Science.gov (United States)

    Joyce, Christopher D.; McIntyre, Toni; Simmons, Sade; LaDuca, Holly; Breitzer, Jonathan G.; Lopez, Carmen M.; Jansen, Andrew N.; Vaughey, J. T.

    Titanium oxides are an important class of lithium-ion battery electrodes owing to their good capacity and stability within the cell environment. Although most Ti(IV) oxides are poor electronic conductors, new methods developed to synthesize nanometer scale primary particles have achieved the higher rate capability needed for modern commercial applications. In this report, the anionic water stable titanium oxalate anion [TiO(C 2O 4) 2] 2- was isolated in high yield as the insoluble DABCO (1,4-diazabicyclo[2.2.2]octane) salt. Powder X-ray diffraction studies show that the titanium dioxide material isolated after annealing in air is initially amorphous, converts to N-doped anatase above 400 °C, then to rutile above 600 °C. Electrochemical studies indicate that the amorphous titanium dioxide phase within a carbon matrix has a stable cycling capacity of ∼350 mAh g -1. On crystallizing at 400 °C to a carbon-coated anatase the capacity drops to 210 mAh g -1, and finally upon carbon burn-off to 50 mAh g -1. Mixtures of the amorphous titanium dioxide and Li 4Ti 5O 12 showed a similar electrochemical profile and capacity to Li 4Ti 5O 12 but with the addition of a sloping region to the end of the discharge curve that could be advantageous for determining state-of-charge in systems using Li 4Ti 5O 12.

  9. Synthesis of cadmium oxide doped ZnO nanostructures using electrochemical deposition

    International Nuclear Information System (INIS)

    Singh, Trilok; Pandya, D.K.; Singh, R.

    2011-01-01

    Research highlights: → Ternary ZnCdO alloy semiconductor nanostructures were grown using electrochemical deposition. → X-ray diffraction measurements showed that the nanostructures were of wurtzite structure and possessed a compressive stress along the c-axis direction. → The cut-off wavelength shifted from blue to red on account of the Cd incorporation in the ZnO and the average transmittance decreased by ∼31%. → The bandgap tuning for 4-16 at% Cd in the initial solution was achieved in the range of 3.08-3.32 eV (up to 0.24 eV). - Abstract: Ternary ZnCdO alloy semiconductor nanostructures were grown using electrochemical deposition. Crystalline nanostructures/nanorods with cadmium concentration ranging from 4 to 16 at% in the initial solution were electrodeposited on tin doped indium oxide (ITO) conducting glass substrates at a constant cathodic potential -0.9 V and subsequently annealed in air at 300 deg. C. X-ray diffraction measurements showed that the nanostructures were of wurtzite structure and possessed a compressive stress along the c-axis direction. The elemental composition of nanostructures was confirmed by energy dispersive spectroscopy (EDS). ZnO nanostructures were found to be highly transparent and had an average transmittance of 85% in the visible range of the spectrum. After the incorporation of Cd content into ZnO the average transmittance decreased and the bandgap tuning was also achieved.

  10. Synthesis, characterization and electrochemical investigations of mixed-ligand copper(II)-organic supramolecular frameworks

    Science.gov (United States)

    Singh, Sandeep K.; Srivastava, Ashish Kumar; Srivastava, Krishna; Banerjee, Rahul; Prasad, Jagdish

    2017-11-01

    Two mixed-ligand copper(II)-organic coordination compounds with 5,5‧-dimethyl-2,2‧-bipyridine (5,5‧-Me2bpy) as a primary ligand while aliphatic malonate (Hmal) and aromatic 2-hydroxynicotinate (2-OHNA) as secondary ligands, were synthesized. These complexes are formulated as: [Cu(Hmal)(5,5‧-Me2bpy)(H2O)](ClO4) 1 and [Cu2(2-OHNA)2(5,5‧-Me2bpy)2(NO3)](NO3) 2. These two complexes were structurally characterized by single crystal X-ray diffraction analysis. Characterization was further supported by powder X-ray diffraction analysis, elemental analyses, FT-IR, FAB-MASS and TGA, DSC studies. Cyclic voltammetric and UV-visible spectral studies of these two complexes have also been done. The electrochemical studies of complex 1 in DMSO and DMF have shown that this complex undergoes quasi-reversible diffusion-controlled one-electron transfer reaction without any chemical complication while complex 2 in DMSO undergoes quasi-reversible diffusion-controlled one electron transfer reaction, following EC mechanism. The electrochemical behaviour of complex 2 in DMF is complicated probably due to presence of more than one species in solution phase.

  11. Electrochemical synthesis of hydrogen peroxide: Rotating disk electrode and fuel cell studies

    International Nuclear Information System (INIS)

    Lobyntseva, Elena; Kallio, Tanja; Alexeyeva, Nadezda; Tammeveski, Kaido; Kontturi, Kyoesti

    2007-01-01

    The electrochemical reduction of oxygen on various catalysts was studied using the thin-layer rotating disk electrode (RDE) method. High-surface-area carbon was modified with an anthraquinone derivative and gold nanoparticles. Polytetrafluoroethylene (PTFE) and cationic polyelectrolyte (FAA) were used as binders in the preparation of thin-film electrodes. Our primary goal was to find a good electrocatalyst for the two-electron reduction of oxygen to hydrogen peroxide. All electrochemical measurements were carried out in 0.1 M KOH. Cyclic voltammetry was used in order to characterise the surface processes of the modified electrodes in O 2 -free electrolyte. The RDE results revealed that the carbon-supported gold nanoparticles are active catalysts for the four-electron reduction of oxygen in alkaline solution. Anthraquinone-modified high-area carbon catalyses the two-electron reduction at low overpotentials, which is advantageous for hydrogen peroxide production. In addition, the polymer electrolyte fuel cell technology was used for the generation of hydrogen peroxide. The cell was equipped with a bipolar membrane which consisted of commercial Nafion 117 as a cation-exchange layer and FT-FAA as an anion-exchange layer. The bipolar membranes were prepared by a hot pressing method. Use of the FAA ionomer as a binder for the anthraquinone-modified carbon catalyst resulted in production of hydrogen peroxide

  12. Facile synthesis of MnO{sub 2}/CNT nanocomposite and its electrochemical performance for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Wang Hongjuan, E-mail: cehjwang@scut.edu.cn [School of Chemistry and Chemcial Engineering, South China University of Technology, Guangzhou, 510640 (China); Peng Cheng [School of Chemistry and Chemcial Engineering, South China University of Technology, Guangzhou, 510640 (China); Peng Feng, E-mail: cefpeng@scut.edu.cn [School of Chemistry and Chemcial Engineering, South China University of Technology, Guangzhou, 510640 (China); Yu Hao; Yang Jian [School of Chemistry and Chemcial Engineering, South China University of Technology, Guangzhou, 510640 (China)

    2011-08-25

    Highlights: > MnO{sub 2}/CNTs are prepared by direct redox reaction between KMnO{sub 4} and carbon nanotubes. > This preparation method is a simple and green without any other additives. > MnO{sub 2}/CNTs show specific capacitance of 162.2 F g{sup -1} at the current density of 0.2 A g{sup -1}. > MnO{sub 2}/CNTs exhibit excellent charge-discharge property. - Abstract: A nanocomposite of manganese dioxide coated on the carbon nanotubes (MnO{sub 2}/CNTs) was synthesized by a facile direct redox reaction between potassium permanganate and carbon nanotubes without any other oxidant or reductant addition. The morphology, microstructure and crystalline form of this MnO{sub 2}/CNT nanocomposite were characterized by scanning electron microscopy (SEM), transition electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The electrochemical properties are characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge/discharge (GCD). The results show that the facile prepared MnO{sub 2}/CNTs nanocomposite shows specific capacitance of 162.2 F g{sup -1} at the current density of 0.2 A g{sup -1} and excellent charge/discharge property with 90% of its specific capacitance kept after 2000 cycles at the current density of 5 A g{sup -1}.

  13. Microwave synthesis of molybdenum doped LiFePO4/C and its electrochemical studies.

    Science.gov (United States)

    Naik, Amol; P, Sajan C

    2016-05-10

    A Mo-doped LiFePO4 composite was prepared successfully from an iron carbonyl complex by adopting a facile and rapid microwave assisted solid state method. The evolution of gases from the iron precursor produces a highly porous product. The formation and substitution of Mo in LiFePO4 were confirmed by X-ray diffraction; surface analysis was carried out by scanning electron microscopy, field emission scanning electron microscopy, and transmission electron microscopy. The electrochemical properties of the substituted LiFePO4 were examined by cyclic voltammetry, electrochemical impedance spectroscopy and by recording charge-discharge cycles. It was observed that the as prepared composites consisted of a single phase orthorhombic olivine-type structure, where Mo(6+) was successfully introduced into the M2(Fe) sites. Incorporation of supervalent Mo(6+) introduced Li(+) ion vacancies in LiFePO4. The synthesized material facilitated lithium ion diffusion during charging/discharging due to the charge compensation effect and porosity. The battery performance studies showed that LiMo0.05Fe0.095PO4 exhibited a maximum capacity of 169.7 mA h g(-1) at 0.1 C current density, with admirable stability retention. Even at higher current densities, the retention of the specific capacity was exceptional.

  14. Microwave synthesis of copper network onto lithium iron phosphate cathode materials for improved electrochemical performance

    International Nuclear Information System (INIS)

    Hsieh, Chien-Te; Liu, Juan-Ru; Juang, Ruey-Shin; Lee, Cheng-En; Chen, Yu-Fu

    2015-01-01

    Herein reported is an efficient microwave-assisted (MA) approach for growing Cu network onto LiFePO 4 (LFP) powders as cathode materials for high-performance Li-ion batteries. The MA approach is capable of depositing highly-porous Cu network, fully covered the LFP powders. The electrochemical performance of Cu-coated LFP cathodes are well characterized by charge/discharge cycling and electrochemical impedance spectroscopy (EIS). The Cu network acts as the key role in improving the specific capacity, rate capability, electrode polarization, as compared to fresh LFP cathode without the Cu coating. The EIS incorporated with equivalent circuit reveals that the completed Cu network obviously suppresses the charge transfer resistance. This result can be attributed to the fact that the Cu network ensures the LFP crystals to get electron easily, alleviating the electrode polarization in view of one-dimensional Li + ion mobility in the olivine crystals. Based on the analysis of Randles plots, the relatively higher Li + diffusion coefficient reflects the more efficient Li + pathway in the LFP powders through the aid of porous Cu network. - Highlights: • An efficient route was used to prepare Cu/LiFePO 4 (LFP) hybrid as cathode material. • The Cu/LFP cathodes exhibit an improved performance as compared to fresh LFP one. • The microwave approach can deposit Cu network, fully covered the LFP powders. • The Cu network ensures LFP to get electrons, alleviating electrode polarization

  15. Synthesis, electrochemical, structural and theoretical study of new derivatives of OABAN and OABAO heterocycles

    Czech Academy of Sciences Publication Activity Database

    Mikysek, T.; Kvapilová, Hana; Doušová, H.; Josefík, F.; Šimůnek, P.; Růžičková, Z.; Ludvík, Jiří

    2017-01-01

    Roč. 455, č. 2 (2017), s. 465-472 ISSN 0020-1693 R&D Projects: GA MŠk LD14129 Institutional support: RVO:61388955 Keywords : boron heterocycles * synthesis * electrochemistry Subject RIV: CG - Electrochemistry OBOR OECD: Electrochemistry (dry cells, batteries, fuel cells, corrosion metals, electrolysis) Impact factor: 2.002, year: 2016

  16. Synthesis, crystal structure and electrochemical properties of the manganese-doped LiNaFe[PO{sub 4}]F materials

    Energy Technology Data Exchange (ETDEWEB)

    Ben Yahia, Hamdi, E-mail: benyahia.hamdi@aist.go.jp; Shikano, Masahiro, E-mail: shikano.masahiro@aist.go.jp; Sakaebe, Hikari; Kobayashi, Hironori

    2013-08-15

    The new compounds LiNaFe{sub 1−x}Mn{sub x}[PO{sub 4}]F (x ≤ 1/4) were synthesized by a solid state reaction route. The crystal structure of LiNaFe{sub 3/4}Mn{sub 1/4}[PO{sub 4}]F was determined from single crystal X-ray diffraction data. LiNaFe{sub 3/4}Mn{sub 1/4}[PO{sub 4}]F crystallizes with the Li{sub 2}Ni[PO{sub 4}]F-type structure, space group Pnma, a = 10.9719(13), b = 6.3528(7), c = 11.4532(13) Å, V = 798.31(16) Å{sup 3}, and Z = 8. The structure consists of edge-sharing (Fe{sub 3/4}Mn{sub 1/4})O{sub 4}F{sub 2} octahedra forming (Fe{sub 3/4}Mn{sub 1/4})FO{sub 3} chains running along the b-axis. These chains are interlinked by PO{sub 4} tetrahedra forming a three-dimensional framework with the tunnels and the cavities filled by the well-ordered sodium and lithium atoms, respectively. The manganese-doped phases show poor electrochemical behavior comparing to the iron pure phase LiNaFe[PO{sub 4}]F. - Highlights: • We investigated the synthesis of LiNaFe{sub 1−x}Mn{sub x}[PO{sub 4}]F by solid state reaction. • We demonstrated that a solid solution exist only for x ≤ 1/4. • We solved the crystal structure of LiNaFe{sub 3/4}Mn{sub 1/4}[PO{sub 4}]F using single crystal data. • We studied the electrochemical performances of LiNaFe{sub 1−x}Mn{sub x}[PO{sub 4}]F. • The Mn-doped phases have poor electrochemical performances comparing to LiNaFe[PO{sub 4}]F.

  17. Synthesis of Bi2WO6 nanoparticles and its electrochemical properties in different electrolytes for pseudocapacitor electrodes

    International Nuclear Information System (INIS)

    Nithya, V.D.; Kalai Selvan, R.; Kalpana, D.; Vasylechko, Leonid; Sanjeeviraja, C.

    2013-01-01

    Highlights: • A simple, economical and environmentally benign sonochemical technique was utilized for the synthesis of homogeneous Bi 2 WO 6 nanoparticles. • This is the first attempt to employ Bi 2 WO 6 as a supercapacitor electrode material. • Effect of electrolyte on the capacitive behaviour of the material is studied. • Bi 2 WO 6 displays good capacitive behaviour in 1 M KOH compared with 1 M NaOH and 1 M LiOH and possess sufficient capacity retention. • It presented an energy density of 67 Wh/kg in the potential range from −0.9 V to 0.1 V and it would be a promising negative electrode for supercapacitor. -- Abstract: Nanosized Bi 2 WO 6 particles were successfully synthesized by sonochemical method with an objective to develop an inexpensive and eco-friendly electrode material for supercapacitors. The prepared material was subjected to various thermal, structural, morphological, compositional, electrical and electrochemical studies. Bi 2 WO 6 nanoparticle with homogeneous distribution was achieved through sonochemical process. The lattice parameter and atomic positions of Bi 2 WO 6 structure were refined through Reitveld analysis. The electrochemical performance of Bi 2 WO 6 nanoparticles was investigated in various aqueous electrolytes such as 1 M NaOH, 1 M LiOH, 1 M Na 2 SO 4 , 1 M KOH and 6 M KOH solutions. Among these, the material exhibited an enhanced electrochemical performance in KOH electrolyte due to its smaller hydration sphere radius, high ionic mobility and lower equivalent series resistance. The charge–discharge studies rendered a specific capacitance of 608 F/g in 1 M KOH at a current density of 0.5 mA/cm 2 . Bi 2 WO 6 exhibited an excellent coulombic efficiency and specific capacitance of around 304 F/g at 3 mA/cm 2 in the potential range from −0.9 to 0.1 V vs Hg/HgO in 1 M KOH electrolyte. The above results assured that Bi 2 WO 6 could be utilized as suitable negative electrode material for supercapacitor applications and 1 M

  18. Highly stable copper oxide composite as an effective photocathode for water splitting via a facile electrochemical synthesis strategy

    KAUST Repository

    Zhang, Zhonghai

    2012-01-01

    . Thus, the electrochemical strategy proposed in this study for the synthesis of the Cu 2O/CuO composite opens a new way to use copper oxides as photocathode materials in PEC cells for a highly stable and effective water splitting. © 2012 The Royal Society of Chemistry.

  19. Synthesis and electrochemical properties of different sizes of the CuO particles

    International Nuclear Information System (INIS)

    Zhang Xiaojun; Zhang Dongen; Ni Xiaomin; Song Jimei; Zheng Huagui

    2008-01-01

    Well-dispersed cupric oxide (CuO) nanoparticles with the size from 10 to 100 nm were successfully synthesized by thermal decomposition of CuC 2 O 4 precursor at 400 deg. C. The prepared CuO nanoparticles of different sizes used as anode materials for Li ion battery all exhibit high electrochemical capacity at the first discharge. However, with the particles size changing, an interesting phenomenon appears. That is, the larger size of the particles is, the discharge capacity of the first time smaller is, while that of the second time is larger. At the same time, the mechanism of the above phenomenon is discussed in this paper. Surprisingly, we have synthesized the copper nanoparticles with different sizes by the CuO of different sizes as the electrodes

  20. Electrochemical synthesis of mesoporous gold films toward mesospace-stimulated optical properties

    Science.gov (United States)

    Li, Cuiling; Dag, Ömer; Dao, Thang Duy; Nagao, Tadaaki; Sakamoto, Yasuhiro; Kimura, Tatsuo; Terasaki, Osamu; Yamauchi, Yusuke

    2015-03-01

    Mesoporous gold (Au) films with tunable pores are expected to provide fascinating optical properties stimulated by the mesospaces, but they have not been realized yet because of the difficulty of controlling the Au crystal growth. Here, we report a reliable soft-templating method to fabricate mesoporous Au films using stable micelles of diblock copolymers, with electrochemical deposition advantageous for precise control of Au crystal growth. Strong field enhancement takes place around the center of the uniform mesopores as well as on the walls between the pores, leading to the enhanced light scattering as well as surface-enhanced Raman scattering (SERS), which is understandable, for example, from Babinet principles applied for the reverse system of nanoparticle ensembles.

  1. Electrochemical synthesis and characterization of hierarchically branched ZnO nanostructures on ensembles of gold nanowires

    International Nuclear Information System (INIS)

    Ongaro, Michael; Gambirasi, Arianna; Favaro, Monica; Ugo, Paolo

    2012-01-01

    Highlights: ► ZnO branched nanofibres for photoelectrochemical applications. ► Branched nanostructures are obtained by electrochemical deposition of ZnO on gold template nanowires. ► Branched nanowires crystallographic phase determined by electron back scatter diffraction. ► Branched structures display improved performances for the photoelectrochemical oxidation of water. - Abstract: This study presents an electrosynthetic methodology to obtain hierarchically structured ZnO electrodes with improved surface area, by exploiting gold nanowires ensembles (3D-NEEs) as the growing substrate. By this way, semiconductor electrodes organized in the shape of fir-like branches are obtained. Branched nanofibres are characterized by electron microscopy and electron backscatter diffraction (EBSD), the latter technique allowing the determination of the crystalline habit of individual nanostructures. The hierarchical branched nanowires show enhanced performances with respect to water photooxidation in comparison with already known nanostructured materials such as 1D-ZnO nanowires.

  2. Synthesis and electrochemical properties of tetrathienyl-linked branched polymers with various aromatic cores

    International Nuclear Information System (INIS)

    Idzik, Krzysztof R.; Frydel, Jaroslaw; Beckert, Rainer; Ledwon, Przemyslaw; Lapkowski, Mieczyslaw; Fasting, Carlo; Müller, Carsten; Licha, Tobias

    2012-01-01

    A series of various tris(2,2′-bithiophen-5-yl)-aromatic derivatives were synthesized by Stille cross-coupling procedure. Their structures were characterized by 1 H NMR, 13 C NMR, and elemental analysis. DFT calculations for monomers were also performed. The optical properties of the synthesized materials as well as their energy levels were investigated by UV–vis absorption supported by fluorescence spectra and CV analysis. Oligomers obtained in the process of electropolymerization, possess a tetrathienyl bond with various aromatic and heteroaromatic cores. Electrochemical results confirm that the gained materials can apply successfully for a diversity of organic–electronic devices like organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs), and organic solar cells.

  3. Electrochemical synthesis of birnessite-type layered manganese oxides for rechargeable lithium batteries

    Science.gov (United States)

    Nakayama, Masaharu; Kanaya, Taku; Lee, Jong-Won; Popov, Branko N.

    Layered manganese dioxide (MnO 2) films intercalated with Li +, Na + or Mg 2+ ions were synthesized by a one-step electrochemical method. The electrodeposition was potentiostatically performed by applying an anodic potential of 1.0 V vs. Ag/AgCl in an aqueous MnSO 4 solution containing a perchlorate salt of the cation. The electrodeposited oxide films have a birnessite-type layered structure with alkali cations and water molecules between manganese oxide layers. The galvanostatic charge-discharge experiments performed in 1 M LiPF 6-DME/PC solution indicated that the Mg 2+-intercalated MnO 2 electrode exhibits an initial discharge capacity as large as 140 mAh g -1 and it shows a better capacity retention during cycling as compared with the Li +- or Na +-intercalated MnO 2 electrode.

  4. The Challenge of Electrochemical Ammonia Synthesis: A New Perspective on the Role of Nitrogen Scaling Relations.

    Science.gov (United States)

    Montoya, Joseph H; Tsai, Charlie; Vojvodic, Aleksandra; Nørskov, Jens K

    2015-07-08

    The electrochemical production of NH3 under ambient conditions represents an attractive prospect for sustainable agriculture, but electrocatalysts that selectively reduce N2 to NH3 remain elusive. In this work, we present insights from DFT calculations that describe limitations on the low-temperature electrocatalytic production of NH3 from N2 . In particular, we highlight the linear scaling relations of the adsorption energies of intermediates that can be used to model the overpotential requirements in this process. By using a two-variable description of the theoretical overpotential, we identify fundamental limitations on N2 reduction analogous to those present in processes such as oxygen evolution. Using these trends, we propose new strategies for catalyst design that may help guide the search for an electrocatalyst that can achieve selective N2 reduction. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Clean and Green Synthesis of New Benzothiazole Derivatives via Electrochemical Oxidation of Catechol Derivatives

    Directory of Open Access Journals (Sweden)

    Mansour Arab Chamjangali

    2016-06-01

    Full Text Available Electrochemical oxidation of the catechols 1a and 1b is studied in the presence of 6-methyl-2-thouracil (3b and 6-propyl-2-thiouracil (3a as nucleophiles in a phosphate buffer (0.15 mol L−1, pH = 6.8/DMF (95:5 solution using cyclic voltammetry and controlled-potential coulometry. The results obtained indicate that the quinones derived from the catechols participate in 1,4-Michael-addition reactions with the nucleophiles to form the corresponding new benzothiazole compounds. In this work, we derive a variety of products with good yields using controlled potential at graphite electrodes in an undivided cell. This work is licensed under a Creative Commons Attribution 4.0 International License.

  6. Controllable synthesis of MnO2/polyaniline nanocomposite and its electrochemical capacitive property

    Science.gov (United States)

    Meng, Fanhui; Yan, Xiuling; Zhu, Ye; Si, Pengchao

    2013-04-01

    Polyaniline (PANI) and MnO2/PANI composites are simply fabricated by one-step interfacial polymerization. The morphologies and components of MnO2/PANI composites are modulated by changing the pH of the solution. Formation procedure and capacitive property of the products are investigated by XRD, FTIR, TEM, and electrochemical techniques. We demonstrate that MnO2 as an intermedia material plays a key role in the formation of sample structures. The MnO2/PANI composites exhibit good cycling stability as well as a high capacitance close to 207 F g-1. Samples fabricated with the facile one-step method are also expected to be adopted in other field such as catalysis, lithium ion battery, and biosensor.

  7. Electrochemical Sensing, Photocatalytic and Biological Activities of ZnO Nanoparticles: Synthesis via Green Chemistry Route

    Science.gov (United States)

    Yadav, L. S. Reddy; Archana, B.; Lingaraju, K.; Kavitha, C.; Suresh, D.; Nagabhushana, H.; Nagaraju, G.

    2016-05-01

    In this paper, we have successfully synthesized ZnO nanoparticles (Nps) via solution combustion method using sugarcane juice as the novel fuel. The structure and morphology of the synthesized ZnO Nps have been analyzed using various analytical tools. The synthesized ZnO Nps exhibit excellent photocatalytic activity for the degradation of methylene blue dye, indicating that the ZnO Nps are potential photocatalytic semiconductor materials. The synthesized ZnO Nps also show good electrochemical sensing of dopamine. ZnO Nps exhibit significant bactericidal activity against Klebsiella aerogenes, Pseudomonas aeruginosa, Eschesichia coli and Staphylococcus aureus using agar well diffusion method. Furthermore, the ZnO Nps show good antioxidant activity by potentially scavenging 1-diphenyl-2-picrylhydrazyl (DPPH) radicals. The above studies clearly demonstrate versatile applications of ZnO synthesized by simple eco-friendly route.

  8. Electrochemical synthesis of gold nanoparticles onto indium tin oxide glass and application in biosensors

    Energy Technology Data Exchange (ETDEWEB)

    Hu Yanling; Song Yan; Wang Yuan; Di Junwei, E-mail: djw@suda.edu.cn

    2011-07-29

    A simple one-step method for the electrochemical deposition of gold nanoparticles (GNPs) onto bare indium tin oxide film coated glass substrate without any template or surfactant was investigated. The effect of electrolysis conditions such as potential range, temperature, concentration and deposition cycles were examined. The connectivity of GNPs was analyzed by UV-Vis absorption spectroscopy and scanning electron microscopy. The nanoparticles were found to connect in pairs or to coalesce in larger numbers. The twin GNPs display a transverse and a longitudinal localized surface plasmon resonance (LSPR) band, which is similar to that of gold nanorods. The presence of longitudinal LSPR band correlates with high refractive index sensitivity. Conjugation of the twin-linked GNPs with albumin bovine serum-biotin was employed for the detection of streptavidin as a model based on the specific binding affinity in biotin/streptavidin pairs. The spectrophotometric sensor showed concentration-dependent binding for streptavidin.

  9. Synthesis and electrochemical properties of silicon nanosheets by DC arc discharge for lithium-ion batteries.

    Science.gov (United States)

    Yu, Xiuhong; Xue, Fanghong; Huang, Hao; Liu, Chunjing; Yu, Jieyi; Sun, Yuejun; Dong, Xinglong; Cao, Guozhong; Jung, Youngguan

    2014-06-21

    Two-dimensional (2D) ultrathin silicon nanosheets (Si NSs) were synthesized by DC arc discharge method and investigated as anode material for Li-ion batteries. The 2D ultrathin characteristics of Si NSs is confirmed by means of transmission electron microscopy (TEM) and atomic force microscopy (AFM). The average size of Si NSs is about 20 nm, with thickness less than 2.5 nm. The characteristic Raman peak of Si NSs is found to have an appreciable (20 nm) shift to low frequency, presumably due to the size effect. The synergistic effects of Ar(+) and H(+) lead to 2D growth of Si NSs under high temperature and energy. Electrochemical analyses reveal that Si NSs anode possesses stable cycling performance and fast diffusion of Li-ions with insertion/extraction processes. Such Si NSs might be a promising candidate for anode of Li-ion batteries.

  10. Synthesis of hydrothermally reduced graphene/MnO2 composites and their electrochemical properties as supercapacitors

    Science.gov (United States)

    Li, Zhangpeng; Wang, Jinqing; Liu, Sheng; Liu, Xiaohong; Yang, Shengrong

    2011-10-01

    Hydrothermally reduced graphene/MnO2 (HRG/MnO2) composites were synthesized by dipping HRG into the mixed aqueous solution of 0.1 M KMnO4 and 0.1 M K2SO4 for different periods of time at room temperature. The morphology and microstructure of the as-prepared composites were characterized by field-emission scanning electron microscopy, X-ray diffraction, Raman microscope, and X-ray photoelectron spectroscopy. The characterizations indicate that MnO2 successfully deposited on HRG surfaces and the morphology of the HRG/MnO2 shows a three-dimensional porous structure with MnO2 homogenously distributing on the HRG surfaces. Capacitive properties of the synthesized composite electrodes were studied using cyclic voltammetry and electrochemical impedance spectroscopy in a three-electrode experimental setup using 1 M Na2SO4 aqueous solution as electrolyte. The main results of electrochemical tests are drawn as follows: the specific capacitance value of HRG/MnO2-200 (HRG dipped into the mixed solution of 0.1 M KMnO4 and 0.1 M K2SO4 for 200 min) electrode reached 211.5 F g-1 at a potential scan rate of 2 mV s-1; moreover, this electrode shows a good cyclic stability and capacity retention. It is anticipated that the synthesized HRG/MnO2 composites will find promising applications in supercapacitors and other devices in virtue of their outstanding characters of good cycle stability, low cost and environmentally benign nature.

  11. Synthesis, characterization, magnetic and electrochemical properties of a new 3D hexa-copper-substituted germanotungstate

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yanzhou; Luo, Jie; Zhang, Yanting [Institute of Molecular and Crystal Engineering, Henan Key Lab of Polyoxometalate Chemistry, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China); Zhao, Junwei, E-mail: zhaojunwei@henu.edu.cn [Institute of Molecular and Crystal Engineering, Henan Key Lab of Polyoxometalate Chemistry, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China); Basic Experiment Teaching Center, Henan University, Kaifeng, Henan 475004 (China); Chen, Lijuan, E-mail: ljchen@henu.edu.cn [Institute of Molecular and Crystal Engineering, Henan Key Lab of Polyoxometalate Chemistry, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China); State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Ma, Pengtao; Niu, Jingyang [Institute of Molecular and Crystal Engineering, Henan Key Lab of Polyoxometalate Chemistry, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China)

    2013-09-15

    An inorganic–organic hybrid hexa-copper-substituted germanotungstate Na{sub 2}[Cu(dap){sub 2}]{sub 2}[Cu(dap){sub 2}] ([Cu{sub 6}(H{sub 2}O){sub 2}(dap){sub 2}][B-α-GeW{sub 9}O{sub 34}]{sub 2})·4H{sub 2}O (1) (dap=1,2-diaminopropane) has been hydrothermally prepared and characterized by elemental analyses, inductively coupled plasma atomic emission spectrometry (ICP–AES) analyses, IR spectra, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA) and single-crystal X-ray diffraction. 1 displays the six-connected 3D network with the long topological (O′Keefe) vertex symbol is 4·4·6{sub 4}·4·4·4·4·6{sub 4}·4·4·4·6{sub 4}·4·4·4 and the short vertex (Schläfli) symbol of 4{sup 12}6{sup 3}. Magnetic measurements indicate that there are the overall ferromagnetic exchange interactions in the belt-like hexa-Cu{sup II} cluster in 1. Furthermore, the electrochemical behavior and electrocatalysis of 1 modified carbon paste electrode (1-CPE) have been studied. The reductions of nitrite, bromate and hydrogen peroxide are principally mediated by the W{sup VI}-based wave. - Graphical abstract: A hexa-Cu{sup II} sandwiched germanotungstate has been synthesized and structurally characterized. The magnetic, solid-state electrochemical and electrocatalytic properties have been investigated. Display Omitted - Highlights: • Transition-metal substituted polyoxometalates. • Hexa-copper-substituted germanotungstate. • Six-connected 3D network. • Electrocatalytic reduction of nitrite, bromate and hydrogen peroxide.

  12. Facile synthesis and electrochemical performances of binder-free flexible graphene/acetylene black sandwich film

    International Nuclear Information System (INIS)

    Xu, Juan; Wei, Xicheng; Cao, Jianyu; Dong, Yuanzhu; Wang, Guoxin; Xue, Yufei; Wang, Wenchang; Chen, Zhidong

    2015-01-01

    Graphene/acetylene black sandwich film was fabricated by a simple vacuum filtration procedure using a stable complex suspension of graphene oxide (GO) and acetylene black followed by a hydroiodic acid (HI) immersion process to fully reduce the GO to graphene sheets. The self-restacking of individual graphene sheets were greatly alleviated and electric conductivity was obviously improved using the acetylene black nanoparticles as both effective spacers to expand the inter-layer interval of the individual graphene sheets during the film assembly course and highly conducting bridges to facilitate the electron/ion transfer between the upper and lower graphene sheets. The flexible graphene/acetylene black film was utilized as supercapacitor electrode without additional conductive additives, binders and current collectors, which achieved an obviously higher specific capacitance (ca. 136.6 F g −1 at 0.5 A g −1 ) and much better specific capacitance retention at high current densities than that of the pure graphene film electrode, indicating that such a novel sandwich film structure allows for a higher charge storage capability. More importantly, the assembled symmetric supercapacitor device displayed a satisfactory specific capacitance of 59.2 F g −1 at 0.1 A g −1 , 47.6 F g −1 at 0.5 A g −1 and 42.8 F g −1 at 1 A g −1 , and only negligible 4.05% capacitance degradation have been found after 1000 continuous charge-discharge cycles at 0.5 A g −1 , revealing outstanding rate capability, excellent electrochemical reversibility and long-term cyclability. These results proved that such a flexible and highly conductive graphene/acetylene black film can be promising electroactive materials in the development of advanced electrochemical energy storage devices

  13. Synthesis, characterization, magnetic and electrochemical properties of a new 3D hexa-copper-substituted germanotungstate

    International Nuclear Information System (INIS)

    Li, Yanzhou; Luo, Jie; Zhang, Yanting; Zhao, Junwei; Chen, Lijuan; Ma, Pengtao; Niu, Jingyang

    2013-01-01

    An inorganic–organic hybrid hexa-copper-substituted germanotungstate Na 2 [Cu(dap) 2 ] 2 [Cu(dap) 2 ] ([Cu 6 (H 2 O) 2 (dap) 2 ][B-α-GeW 9 O 34 ] 2 )·4H 2 O (1) (dap=1,2-diaminopropane) has been hydrothermally prepared and characterized by elemental analyses, inductively coupled plasma atomic emission spectrometry (ICP–AES) analyses, IR spectra, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA) and single-crystal X-ray diffraction. 1 displays the six-connected 3D network with the long topological (O′Keefe) vertex symbol is 4·4·6 4 ·4·4·4·4·6 4 ·4·4·4·6 4 ·4·4·4 and the short vertex (Schläfli) symbol of 4 12 6 3 . Magnetic measurements indicate that there are the overall ferromagnetic exchange interactions in the belt-like hexa-Cu II cluster in 1. Furthermore, the electrochemical behavior and electrocatalysis of 1 modified carbon paste electrode (1-CPE) have been studied. The reductions of nitrite, bromate and hydrogen peroxide are principally mediated by the W VI -based wave. - Graphical abstract: A hexa-Cu II sandwiched germanotungstate has been synthesized and structurally characterized. The magnetic, solid-state electrochemical and electrocatalytic properties have been investigated. Display Omitted - Highlights: • Transition-metal substituted polyoxometalates. • Hexa-copper-substituted germanotungstate. • Six-connected 3D network. • Electrocatalytic reduction of nitrite, bromate and hydrogen peroxide

  14. Synthesis, characterization and electrochemical behavior of Sb-doped ZnO microsphere film

    Energy Technology Data Exchange (ETDEWEB)

    Li, Qian [Department of Materials Science and Engineering, State Key Laboratory of Silicon Materials, Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, Hangzhou, 310027 (China); Cheng, Kui, E-mail: chengkui@zju.edu.cn [Department of Materials Science and Engineering, State Key Laboratory of Silicon Materials, Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, Hangzhou, 310027 (China); Weng, Wenjian, E-mail: wengwj@zju.edu.cn [Department of Materials Science and Engineering, State Key Laboratory of Silicon Materials, Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, Hangzhou, 310027 (China); The Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai, 200050 (China); Du, Piyi; Han, Gaorong [Department of Materials Science and Engineering, State Key Laboratory of Silicon Materials, Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, Hangzhou, 310027 (China)

    2013-10-01

    Sb-doped ZnO microsphere film was fabricated by a carboxylate ion assisted hydrothermal route coupled with a post-calcination process. The structure, chemical composition and optical band gap of the Sb-doped ZnO microsphere film were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, inductively couple plasma optical emission spectroscopy and UV–visible spectrophotometry, and compared with the un-doped ZnO microsphere film. The results suggest that the formation of zinc–antimony tartrate complex species during hydrothermal growth is the key to realize Sb-doped ZnO microstructures, and the present hydrothermal method with post-calcination is an effective way to dope Sb into ZnO. Furthermore, the Sb-doped ZnO microsphere film based electrochemical biosensor exhibits a good sensing performance for the detection of hydrogen peroxide, with a sensitivity of 271 μA mM{sup −1} cm{sup −2} which is more than three times higher than that of the un-doped ZnO biosensor. - Highlights: • Sb-doped ZnO microsphere (SZM) films were grown by hydrothermal deposition. • Carboxylate ions were used to form complex during hydrothermal growth. • The formation of Zn–Sb tartrate complex is the key to realize SZM. • The biosensors based on SZM film are feasible and sensitive to detect H{sub 2}O{sub 2}. • The Sb doping could improve the electrochemical property of ZnO.

  15. Synthesis and characterization of oligobenzimidazoles: Electrochemical, electrical, optical, thermal and rectification properties

    Science.gov (United States)

    Anand, Siddeswaran; Muthusamy, Athianna

    2018-03-01

    A series of benzimidazole monomers, (2-(2, 4-dihydroxyphenyl)-1H-benzimidazol-5-yl)(phenyl) methanone (BIKH), 2-(3-ethoxy-2-hydroxyphenyl)-1H-benzo [d]imidazole-5-yl) (phenyl) methanone (BIKE) and 2-(5-bromo-2-hydroxyphenyl)-1H-benzo [d]imidazole-5-yl) (phenyl) methanone (BIKB) were prepared by condensing three substituted aromatic aldehydes with 3, 4-diaminobenzophenone. In aqueous alkaline medium the benzimidazoles were converted in to oligomers by oxidative polycondensation using NaOCl as oxidant. The formation of monomers and oligomers were confirmed with 1H, 13C NMR, FT-IR, and UV-visible spectroscopic techniques. The oligomers were investigated for their optical, electrical, electrochemical and thermal properties. The electrochemical and optical band gaps of monomers and oligomers were calculated using both UV-visible spectroscopy and cyclic voltametry respectively. The band gap values of monomers are compared with band gap values obtained from quantum theoretical calculations with DFT. The electrical conductivity studies of iodine doped and undoped oligomers were done using two point probe technique. It is found that these values are showing good correlation with the charge densities on imidazole nitrogen obtained from Huckel method. The conductivity of oligomers increases with increase in iodine vapour contact time. The dielectric properties of oligomers have been investigated at different temperature and frequency. The dielectric measurement data were used to calculate the AC conductivity and activation energy of oligomers. Oligomer OBIKH is having greater thermal stability due to its number of chain propagation sites than other oligomers and is shown by its high carbines residue of around 60% at 600 °C in thermogravimetric analysis. I-V characteristics of oligobenzimidazole p-n diodes have shown good rectifying nature in the range -4 to 4 V.

  16. Cyclization of 1,2:3,4-di-O-isopropylidene-α-D-galacto-1,6-hexodialdo-1,5-pyranose acylhydrazone and semicarbazone

    OpenAIRE

    Martins Alho, Miriam Amelia; Baggio, Ricardo Fortunato; D'accorso, Norma Beatriz

    2015-01-01

    Cyclization of 1,2:3,4-di-O-isopropylidene-α-D-galacto-1,6-hexodialdo-1,5-pyranose benzoylhydrazone using acetylating mixtures led us to the corresponding (2R)- and (2S)-5- phenyl-1,3,4-oxadiazoline derivatives. The same conditions applied to the semicarbazone produced the 5-methyl-1,3,4-oxadiazoline derivative as the main compound, which is formed with acetylating mixtures even at room temperature. X-Ray analysis and NMR techniques were used to determine the stereochemistry of the new asymme...

  17. A fast chemical route for the synthesis of TBHQ functionalized reduced graphene oxide and its electrochemical performances

    Energy Technology Data Exchange (ETDEWEB)

    Rana, Subhasis; Sen, Pintu, E-mail: psen@vecc.gov.in; Bandyopadhyay, S.K.

    2016-02-01

    A fast chemical route for the synthesis of tertiary butyl hydroquinone (TBHQ) functionalized reduced graphene oxide (FRGO) and their application as high performance electrode materials for supercapacitors have been reported. Reductions of chemically exfoliated graphene oxides (GO) in the presence of small amount of TBHQ (1–2 wt % with respect to GO) at various time periods were investigated through XRD, FTIR and Raman studies. Reappearance of broad diffraction peak close to graphite peak (002) reveals an efficient method of reduction of different oxygen containing functional groups present in GO/FGO resulting in a decrease of interlayer d-spacing (∼3.5 Å). Absence of the absorption peaks in FTIR for –C=O, t-O–H, epoxide and alkoxy groups supports the complete reduction of GO to FRGO by hydrazine hydrate within a short time period of 4 h reduction under reflux condition. A large red shift in UV spectrum of FRGO – 4 h (270 nm) reveals the complete reduction of graphene oxide. The average crystallite sp{sup 2} domains sizes have been estimated through Raman spectroscopy. Plausible mechanism of TBHQ assisted fast chemical reduction of FGO has been enumerated. 1.5 wt % TBHQ in FRGO shows the best electrochemical performance where TBHQ not only acts as a reducing agent during functionalization, but also plays as an active redox molecule for enhanced capacitance of 200 F/g. - Highlights: • A fast chemical route has been adopted for the synthesis of TBHQ functionalized RGO. • The kinetics of chemical reduction becomes faster in the presence of TBHQ. • The FTIR spectrum of functionalized RGO supports the complete reduction process. • TBHQ also plays a vital role for enhancing capacitance of functionalized RGO.

  18. A simple biogenic route to rapid synthesis of Au-TiO{sub 2} nanocomposites by electrochemically active biofilms

    Energy Technology Data Exchange (ETDEWEB)

    Kalathil, Shafeer; Khan, Mohammad Mansoob [Yeungnam University, School of Chemical Engineering (Korea, Republic of); Banerjee, Arghya Narayan [Yeungnam University, School of Mechanical Engineering (Korea, Republic of); Lee, Jintae; Cho, Moo Hwan, E-mail: mhcho@ynu.ac.kr [Yeungnam University, School of Chemical Engineering (Korea, Republic of)

    2012-08-15

    Deposition of gold on titanium dioxide (TiO{sub 2}) nanoparticles is highly beneficial for maximizing the efficiency of many photocatalytic reactions. In this study, we have reported for the first time the use of an electrochemically active biofilm (EAB) for the synthesis of Au-TiO{sub 2} nanocomposite with sodium acetate as the electron donor. The EAB acts as an electron generator for the reduction of gold ions on the surface of TiO{sub 2} nanoparticles. It was observed that the TiO{sub 2} plays not only as a support for the gold nanoparticles but also as a storage of electrons produced by the EAB within the particles. These stored electrons dramatically increase the reduction of gold ions and hence we have observed the formation of the Au-TiO{sub 2} nanocomposites within 90 min. A mechanism of the nanocomposite formation is also proposed. The as-synthesized nanocomposites were characterized by UV-Vis absorption spectroscopy to monitor the proper formation of the nanocomposites. X-ray diffraction and transmission electron microscopic analyses were performed to determine the structural and microstructural properties of the nanocomposites. High-resolution transmission electron micrographs depict the proper formation of the Au-TiO{sub 2} nanocomposites with gold nanoparticle size varying from 5 to 10 nm with an increase in the gold precursor concentration. Zeta potential measurements were used to investigate surface charges of the as-synthesized nanocomposites. This novel biogenic route represents a unique pathway for the low cost, eco-friendly, rapid, and controlled synthesis of nanostructured Au-TiO{sub 2} hybrid systems which will truly revolutionize the synthetic fields of nanocomposites.

  19. Synthesis And Electrochemical Characteristics Of Mechanically Alloyed Anode Materials SnS2 For Li/SnS2 Cells

    Directory of Open Access Journals (Sweden)

    Hong J.H.

    2015-06-01

    Full Text Available With the increasing demand for efficient and economic energy storage, tin disulfide (SnS2, as one of the most attractive anode candidates for the next generation high-energy rechargeable Li-ion battery, have been paid more and more attention because of its high theoretical energy density and cost effectiveness. In this study, a new, simple and effective process, mechanical alloying (MA, has been developed for preparing fine anode material tin disulfides, in which ammonium chloride (AC, referred to as process control agents (PCAs, were used to prevent excessive cold-welding and accelerate the synthesis rates to some extent. Meanwhile, in order to decrease the mean size of SnS2 powder particles and improve the contact areas between the active materials, wet milling process was also conducted with normal hexane (NH as a solvent PCA. The prepared powders were both characterized by X-ray diffraction, Field emission-scanning electron microscopeand particle size analyzer. Finally, electrochemical measurements for Li/SnS2 cells were takenat room temperature, using a two-electrode cell assembled in an argon-filled glove box and the electrolyte of 1M LiPF6 in a mixture of ethylene carbonate(EC/dimethylcarbonate (DMC/ethylene methyl carbonate (EMC (volume ratio of 1:1:1.

  20. Polypyrrole–titanium(IV) doped iron(III) oxide nanocomposites: Synthesis, characterization with tunable electrical and electrochemical properties

    International Nuclear Information System (INIS)

    Nandi, Debabrata; Ghosh, Arup Kumar; Gupta, Kaushik; De, Amitabha; Sen, Pintu; Duttachowdhury, Ankan; Ghosh, Uday Chand

    2012-01-01

    Highlights: ► Synthesis and characterization of polymer nanocomposite based on titanium doped iron(III) oxide. ► Electrical conductivity increased 100 times in composite with respect to polymer. ► Electrochemical capacitance of polymer composites increased with nanooxide content. ► Thermal stability of the polymer enhanced with nano oxide content. -- Abstract: Titanium(IV)-doped synthetic nanostructured iron(III) oxide (NITO) and polypyrrole (PPy) nanocomposites was fabricated by in situ polymerization using FeCl 3 as initiator. The polymer nanocomposites (PNCs) and pure NITO were characterized by X-ray diffraction, Föurier transform infrared spectroscopy, scanning electron microscopy, electron dispersive X-ray spectroscopy, transmission electron microscopy, etc. Thermo gravimetric and differential thermal analyses showed the enhancement of thermal stability of PNCs than the pure polymer. Electrical conductivity of the PNCs had increased significantly from 0.793 × 10 −2 S/cm to 0.450 S/cm with respect to the PPy, and that had been explained by 3-dimensional variable range hopping (VRH) conduction mechanisms. In addition, the specific capacitance of PNCs had increased from 147 F/g to 176 F/g with increasing NITO content than that of pure NITO (26 F/g), presumably due to the growing of mesoporous structure with increasing NITO content in PNCs which reduced the charge transfer resistance significantly.

  1. In situ self-sacrificed template synthesis of vanadium nitride/nitrogen-doped graphene nanocomposites for electrochemical capacitors.

    Science.gov (United States)

    Liu, Hong-Hui; Zhang, Hong-Ling; Xu, Hong-Bin; Lou, Tai-Ping; Sui, Zhi-Tong; Zhang, Yi

    2018-03-15

    Vanadium nitride and graphene have been widely used as pseudo-capacitive and electric double-layer capacitor electrode materials for electrochemical capacitors, respectively. However, the poor cycling stability of vanadium nitride and the low capacitance of graphene impeded their practical applications. Herein, we demonstrated an in situ self-sacrificed template method for the synthesis of vanadium nitride/nitrogen-doped graphene (VN/NGr) nanocomposites by the pyrolysis of a mixture of dicyandiamide, glucose, and NH 4 VO 3 . Vanadium nitride nanoparticles of the size in the range of 2 to 7 nm were uniformly embedded into the nitrogen-doped graphene skeleton. Furthermore, the VN/NGr nanocomposites with a high specific surface area and pore volume showed a high specific capacitance of 255 F g -1 at 10 mV s -1 , and an excellent cycling stability (94% capacitance retention after 2000 cycles). The excellent capacitive properties were ascribed to the excellent conductivity of nitrogen-doped graphene, high surface area, high pore volume, and the synergistic effect between vanadium nitride and nitrogen-doped graphene.

  2. Controllable synthesis and electrochemical hydrogen storage properties of Sb₂Se₃ ultralong nanobelts with urchin-like structures.

    Science.gov (United States)

    Jin, Rencheng; Chen, Gang; Pei, Jian; Sun, Jingxue; Wang, Yang

    2011-09-01

    The controlled synthesis of one-dimensional and three-dimensional Sb(2)Se(3) nanostructures has been achieved by a facile solvothermal process in the presence of citric acid. By simply controlling the concentration of citric acid, the nucleation, growth direction and exposed facet can be readily tuned, which brings the different morphologies and nanostructures to the final products. The as-prepared products have been characterized by means of X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM and selected area electron diffraction. Based on the electron microscope observations, a possible growth mechanism of Sb(2)Se(3) with distinctive morphologies including ultralong nanobelts, hierarchical urchin-like nanostructures is proposed and discussed in detail. The electrochemical hydrogen storage measurements reveal that the morphology plays a key role on the hydrogen storage capacity of Sb(2)Se(3) nanostructures. The Sb(2)Se(3) ultralong nanobelts with high percentage of {-111} facets exhibit higher hydrogen storage capacity (228.5 mA h g(-1)) and better cycle stability at room temperature.

  3. Graphene–Gold Nanoparticles Hybrid—Synthesis, Functionalization, and Application in a Electrochemical and Surface-Enhanced Raman Scattering Biosensor

    Directory of Open Access Journals (Sweden)

    Ibrahim Khalil

    2016-05-01

    Full Text Available Graphene is a single-atom-thick two-dimensional carbon nanosheet with outstanding chemical, electrical, material, optical, and physical properties due to its large surface area, high electron mobility, thermal conductivity, and stability. These extraordinary features of graphene make it a key component for different applications in the biosensing and imaging arena. However, the use of graphene alone is correlated with certain limitations, such as irreversible self-agglomerations, less colloidal stability, poor reliability/repeatability, and non-specificity. The addition of gold nanostructures (AuNS with graphene produces the graphene–AuNS hybrid nanocomposite which minimizes the limitations as well as providing additional synergistic properties, that is, higher effective surface area, catalytic activity, electrical conductivity, water solubility, and biocompatibility. This review focuses on the fundamental features of graphene, the multidimensional synthesis, and multipurpose applications of graphene–Au nanocomposites. The paper highlights the graphene–gold nanoparticle (AuNP as the platform substrate for the fabrication of electrochemical and surface-enhanced Raman scattering (SERS-based biosensors in diverse applications as well as SERS-directed bio-imaging, which is considered as an emerging sector for monitoring stem cell differentiation, and detection and treatment of cancer.

  4. First examples of organosilica-based ionogels: synthesis and electrochemical behavior

    Directory of Open Access Journals (Sweden)

    Andreas Taubert

    2017-03-01

    Full Text Available The article describes the synthesis and properties of new ionogels for ion transport. A new preparation process using an organic linker, bis(3-(trimethoxysilylpropylamine (BTMSPA, yields stable organosilica matrix materials. The second ionogel component, the ionic liquid 1-methyl-3-(4-sulfobutylimidazolium 4-methylbenzenesulfonate, [BmimSO3H][PTS], can easily be prepared with near-quantitative yields. [BmimSO3H][PTS] is the proton conducting species in the ionogel. By combining the stable organosilica matrix with the sulfonated ionic liquid, mechanically stable, and highly conductive ionogels with application potential in sensors or fuel cells can be prepared.

  5. Synthesis, exploration of energy storage and electrochemical sensing properties of hematite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ramasami, Alamelu K. [Centre for Nano and Material Sciences, Jain University, Bangalore 562112 (India); Department of Physics, Advanced Batteries Lab, National University of Singapore, 117542 (Singapore); Ravishankar, T.N.; Sureshkumar, K. [Centre for Nano and Material Sciences, Jain University, Bangalore 562112 (India); Reddy, M.V.; Chowdari, B.V.R. [Department of Physics, Advanced Batteries Lab, National University of Singapore, 117542 (Singapore); Ramakrishnappa, T. [Centre for Nano and Material Sciences, Jain University, Bangalore 562112 (India); Balakrishna, Geetha R., E-mail: br.geetha@jainuniversity.ac.in [Centre for Nano and Material Sciences, Jain University, Bangalore 562112 (India)

    2016-06-25

    Gel-combustion, solution combustion and molten salt methods were used to synthesize hematite nanoparicles. Two weight ratios of precursor (Ferric nitrate) to fuel (Cassava Starch) (1:0.5, 1:1) were used in gel-combustion technique. Ferric nitrate as a precursor and ethylenediamine tetraacetic acid as fuel (in stoichiometric proportions) were used in the solution combustion method. Ferric oxalate was the precursor in molten salt method. The structural parameters of the hematite nanoparticles were studied by X-ray diffraction. The optical properties, including band gap studies were done by UV–Visible spectroscopy. The morphological studies were carried out by Scanning Electron Microscope. The energy storage capacity of the molten salt method-hematite nanoparticles surpassed (920 mAhg{sup −1}) the others while the equal-weight- ratio-hematite nanoparticles synthesized by gel-combustion method exhibited better dopamine sensor properties. - Highlights: • Hematite nanoparticles were synthesized by gel, solution combustion and molten salt methods. • Gel-combustion involved the use of natural fuel extracted from the root tubers of Manihot esculenta. • Two ratios of fuel to precursors were attempted in gel combustion method. • The product formed from the equal weight ratio of fuel to precursor was a very good electrochemical dopamine sensor. • The product formed by molten salt method exhibited good battery behaviour (Li-ion battery).

  6. Synthesis, exploration of energy storage and electrochemical sensing properties of hematite nanoparticles

    International Nuclear Information System (INIS)

    Ramasami, Alamelu K.; Ravishankar, T.N.; Sureshkumar, K.; Reddy, M.V.; Chowdari, B.V.R.; Ramakrishnappa, T.; Balakrishna, Geetha R.

    2016-01-01

    Gel-combustion, solution combustion and molten salt methods were used to synthesize hematite nanoparicles. Two weight ratios of precursor (Ferric nitrate) to fuel (Cassava Starch) (1:0.5, 1:1) were used in gel-combustion technique. Ferric nitrate as a precursor and ethylenediamine tetraacetic acid as fuel (in stoichiometric proportions) were used in the solution combustion method. Ferric oxalate was the precursor in molten salt method. The structural parameters of the hematite nanoparticles were studied by X-ray diffraction. The optical properties, including band gap studies were done by UV–Visible spectroscopy. The morphological studies were carried out by Scanning Electron Microscope. The energy storage capacity of the molten salt method-hematite nanoparticles surpassed (920 mAhg"−"1) the others while the equal-weight- ratio-hematite nanoparticles synthesized by gel-combustion method exhibited better dopamine sensor properties. - Highlights: • Hematite nanoparticles were synthesized by gel, solution combustion and molten salt methods. • Gel-combustion involved the use of natural fuel extracted from the root tubers of Manihot esculenta. • Two ratios of fuel to precursors were attempted in gel combustion method. • The product formed from the equal weight ratio of fuel to precursor was a very good electrochemical dopamine sensor. • The product formed by molten salt method exhibited good battery behaviour (Li-ion battery).

  7. Hydrothermal Synthesis and Electrochemical Properties of Spherical α-MnO2 for Supercapacitors.

    Science.gov (United States)

    Chen, Ya; Qin, Wenqing; Fan, Ruijuan; Wang, Jiawei; Chen, Baizhen

    2015-12-01

    In the present work, spherical α-MnO2 with a high specific capacitance was synthesized by a two-step hydrothermal route. MnCO3 precursors were first prepared by a common hydrothermal method, and then converted to α-MnO2 via a hydrothermal reaction between the precursors and KMnO4 solutions. The effects of hydrothermal temperature on the morphology, crystal structure and specific area of the MnO2 were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and BET measurements. The electrochemical capacitive properties of the manganese dioxides with different morphologies and structures were evaluated by cyclic voltammetry and galvonostatic charge-discharge tests. The results showed that the temperature in the second hydrothermal step had prominent impact on the capacitive properties of a-MnO2. The MnO2 synthesized at 150 *C exhibited a highest specific capacitance of 328.4 Fx g(-1) at a charge-discharge current density of 100 mA x g(-1).

  8. Facile synthesis of porous Pt botryoidal nanowires and their electrochemical properties

    International Nuclear Information System (INIS)

    Huang, Zhongyuan; Zhou, Haihui; Chen, Zhongxue; Zeng, Fanyan; Chen, Liang; Luo, Wucheng; Kuang, Yafei

    2014-01-01

    Highlights: • Porous Pt nanowires were synthesized by combination of soft and hard templets. • Te nanowires were used as the hard templet and reductant. • The Pt nanowires are composed of many small Pt nanoparticles and pores. • The Pt nanowires have very good electrochemical activity and stability. - Abstract: Long and porous Pt botryoidal nanowires (Pt BNWs) were facilely synthesized by combination of soft and hard templates accompanying chemical reduction of ascorbic acid and replacement of Te nanowires. This bis-template and bis-reductant method is proved to be an effective way to prepare nanowires with special structure. The scanning electron microscopy and transmission electron microscopy images show the as-prepared product is botryoidal nanowires with diameter of 20–30 nm and length of several micrometers. High resolution transmission electron microscopy shows the Pt botryoidal nanowires are composed of many small Pt nanoparticles (about 3 nm in diameter), which is just like that many grapes grow on the branch. These small nanoparticles make Pt nanowires have botryoidal and porous structure. Moreover, the diameter of Pt BNWs can be adjusted by changing the dosage of Pt precursor, polyvinylpyrrolidone and L-ascorbic acid. The electrocatalytic performance of Pt botryoidal nanowires is studied, which shows that the as-prepared Pt botryoidal nanowires have not only high activity but also good stability for oxygen reduction reaction

  9. Electrochemical zinc insertion into W18O49: Synthesis and characterization of new bronzes

    International Nuclear Information System (INIS)

    Martinez-de la Cruz, A.; Amador, U.; Rodriguez-Carvajal, J.; Garcia-Alvarado, F.

    2005-01-01

    Divalent zinc ions have been electrochemically inserted into W 18 O 49 , producing zinc bronzes. Under our experimental conditions, W 18 O 49 accepts zinc reversibly as a guest up to 0.9 ions per formula. The reaction seems to proceed through the formation of a solid solution in which the W-O framework of the parent oxide is maintained. The location of the Zn 2+ ions in the framework of W 18 O 49 has been determined by neutron diffraction on a chemically prepared sample having the composition Zn 0.34 W 18 O 49 . As a main result, we found that Zn prefers to insert in one of the four types of quadrangular tunnels. More precisely, it is displaced from the center to occupy a low coordination site. This result indicates that a significant covalent character exists in the Zn-O bond. - Graphical Abstract: The structure of Zn 0.36 W 18 O 49 projected along the b-axis

  10. Solvothermal synthesis and electrochemical performance of hollow LiFePO{sub 4} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Zhenmiao [School of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Pang, Wei Kong [Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong, NSW 2522 (Australia); Australian Nuclear Science and Technology Organization, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia); Tang, Xincun, E-mail: tangxincun@163.com [School of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Jia, Dianzeng; Huang, Yudai [Institute of Applied Chemistry, Xinjiang University, Urumqi 840046 (China); Guo, Zaiping [Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong, NSW 2522 (Australia)

    2015-08-15

    Highlights: • Hollow LiFePO{sub 4} nanoparticles were successfully synthesized via solvothermal method. • The shorter b lattice parameter allows the shorter diffusion path of lithium ion. • Hollow LiFePO{sub 4} nanoparticles show better rate capability than solid LiFePO{sub 4}. - Abstract: Hollow LiFePO{sub 4} nanoparticles were synthesized via a solvothermal technique, using ammonium tartrate as additive and carbon source, and ethylene glycol/water as solvent. The as-prepared samples were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, Raman spectroscopy, scanning and transmission electron microscopies, and Brunauer–Emmett–Teller specific surface area measurements. The electrochemical properties of the LiFePO{sub 4} cathode were examined in coin-type cell configuration and the cathode exhibited excellent rate capability (i.e., discharge capacity of 120.9 mA h g{sup −1} at 10 C) and cycling performance (i.e., >98% of capacity retention rate after 50 cycles). It is believed that the enhanced performance is correlated to the hollow structure, small crystallite and particle sizes, and relatively shorter lattice parameter b.

  11. Electrochemical synthesis of novel {pi}-extended phenoxazine derivatives of porphyrincatecholes

    Energy Technology Data Exchange (ETDEWEB)

    Osati, Samira; Davarani, Saied Saeed Hosseiny [Department of Chemistry, Faculty of Science, Shahid Beheshti University, G.C, Evin, 1983963113 Tehran (Iran, Islamic Republic of); Safari, Nasser, E-mail: n-safari@cc.sbu.ac.ir [Department of Chemistry, Faculty of Science, Shahid Beheshti University, G.C, Evin, 1983963113 Tehran (Iran, Islamic Republic of); Banitaba, Mohammad Hossein [Department of Chemistry, Faculty of Science, Shahid Beheshti University, G.C, Evin, 1983963113 Tehran (Iran, Islamic Republic of)

    2011-10-30

    Three new functionalized phenoxazine-catechol porphyrins 7a-c have been synthesized by a green one-pot method and structurally characterized by spectroscopic analysis. The electro-oxidation of 5,10,15,20-tetrakis(2,3-dihydroxyphenyl) porphyrins(1a-c) with four catechol units in the presence of 2-aminophenol 8 as bidentate nucleophile has been done and phenoxazine rings have been formed by intermolecular and intramolecular Michael addition reactions. Spectroscopic characterization and voltammetry results have allowed us to propose four independent ECEC mechanisms for the electrochemical oxidation pathway. The functionalization of the porphyrins affected their photophysical properties. Expansion of the UV-vis spectrum range and the decrease of the fluorescence intensity of the products would support the energy transfer between the porphyrin core excited states to the four substitutions as the electron acceptor subunits. SEM images indicate that this method produces regularly shaped manganese porphyrin nano-particles 7c that possess a cubic nano structure.

  12. Controlled synthesis and electrochemical properties of vanadium oxides with different nanostructures

    International Nuclear Information System (INIS)

    Zhang, Yifu; Zhou, Min; Huang, Chi; Chen, Chongxue; Cao, Yuliang; Fan, Meijuan; Li, Houbin; Liu, Xinghai; Xie, Guangyong

    2012-01-01

    Vanadium oxides (V 3 O 7 .H 2 O and VO 2 ) with different morphologies have been selectively synthesized by a facile hydrothermal approach using glucose as the reducing and structure-directing reagent. The as-obtained V 3 O 7 .H 2 O nanobelts have a length up to several tens of micrometers, width of about 60-150 nm and thickness of about 5-10 nm, while the as-prepared VO 2 (B) nanobelts have a length of about 1.0- 7 μm, width, 80-140 nm and thickness, 2-8 nm. It was found that the quantity of glucose, the reaction temperature and the reaction time had significant influence on the compositions and morphologies of final products. Vanadium oxides with different morphologies were easily synthesized by controlling the concentration of glucose. The formation mechanism was also briefly discussed, indicating that glucose played different roles in synthesizing various vanadium oxides. The phase transition from VO 2 (B) to VO 2 (M) were investigated and the phase transition temperature of the VO 2 (M) appeared at around 68 deg C. Furthermore, the electrochemical properties of V 3 O 7 .H 2 O nanobelts, VO 2 (B) nanobelts and VO 2 (B) nanosheets were investigated and they exhibited a high initial discharge capacity of 296, 247 and 227 mAh/g, respectively. (author)

  13. Highly Soluble Monoamino-Substituted Perylene Tetracarboxylic Dianhydrides: Synthesis, Optical and Electrochemical Properties

    Directory of Open Access Journals (Sweden)

    Kew-Yu Chen

    2014-12-01

    Full Text Available Three dialkylamino-substituted perylene tetracarboxylic dianhydrides with different n-alkyl chain lengths (n = 6, 12 or 18, 1a–1c, were synthesized under mild conditions in high yields and were characterized by 1H NMR, 13C NMR and high resolution mass spectroscopy. Their optical and electrochemical properties were measured using UV-Vis and emission spectroscopic techniques, as well as cyclic voltammetry (CV. This is the first time that the structures and the properties of monoamino-substituted perylene tetracarboxylic dianhydrides have been reported. These molecules show a deep green color in both solution and the solid state and are soluble in most organic solvents. They all show a unique charge transfer emission in the near-infrared region, and the associated peaks exhibit solvatochromism. The dipole moments of the compounds have been estimated using the Lippert-Mataga equation, and upon excitation, they show slightly larger dipole moment changes than those of corresponding perylene diimides, 2a–2c. Additionally, Compounds 1a–1c undergo two quasi-reversible one-electron oxidations and two quasi-reversible one-electron reductions in dichloromethane at modest potentials. Complementary density functional theory calculations performed on these chromophores are reported in order to gain more insight into their molecular structures and optical properties.

  14. Ionic Liquid-Assisted Synthesis of a NiO/CNTs Composite and Its Electrochemical Capacitance

    Directory of Open Access Journals (Sweden)

    Yitong Chen

    2014-01-01

    Full Text Available A novel solid-state method has been developed for synthesizing nickel oxide (NiO/carbon nanotubes (CNTs composite using an ionic liquid (IL, 1-butyl-3-methylimidazolium chloride as the reaction medium. Ultraviolet-visible (UV-vis absorbance spectroscopy, infrared spectroscopy (IR, and scanning electron microscopy (SEM were employed to investigate the structure, morphology, and formation mechanism of the synthesized sample. The results demonstrated that the IL is effective for dispersing CNTs, which allows the tethering of nickel (II ions onto the surfaces of the CNTs and facilitates the subsequent chemical deposition of NiO to obtain the NiO/CNTs composite. The electrochemical properties of the composite were determined using cyclic voltammetry and galvanostatic charge/discharge measurements in 6 M KOH. Because of its unique structure, the prepared NiO/CNTs electrode exhibited good capacitive behavior and cyclability. The high specific capacitance (521 F g−1 and good rate capability (91% capacity retention at 0.5 A g−1 of the NiO/CNTs composite enable its use as a practical supercapacitor electrode material.

  15. Synthesis and Electrochemical Performance of Polyacrylonitrile Carbon Nanostructure Microspheres for Supercapacitor Application

    Directory of Open Access Journals (Sweden)

    Mimgjie Ma

    2015-01-01

    Full Text Available Polyacrylonitrile (PAN carbon nanostructure microspheres (CNM with the average particle size of 200 nm were prepared in the range of 500 to 800°C. The precursors of CNM were obtained through soap-free emulsion polymerization followed by freeze drying, oxidative stabilization, and half-carbonization. KOH was employed as the activation agent of the precursor material, and the ratio between KOH and the precursor was selected as 2 : 1. The element content, pore structure, nitrogen-containing functional groups, and microstructure characterization were characterized via elemental analysis, N2 adsorption at low temperature, X-ray photoelectron spectroscopy (XPS, scanning electron microscopy (SEM, and transmission electron microscopy (TEM, and the electrochemical properties were examined as well. The results revealed that the CNM displayed specific surface area as high as 2134 m2/g and the total pore volume could reach 2.01 cm3/g when the activation temperature was 700°C. Furthermore, its specific capacitance in 3 M KOH and 1 M organic electrolyte could reach 311 F/g and 179 F/g, respectively. And, also, abundant functional groups of N-5 and N-6 were rich in the surface of the material, which could cause Faraday reaction and got the increasing specific capacitance via improvement of the wettability of the electrode material.

  16. Synthesis and Electrochemical Properties of Two-Dimensional RGO/Ti3C2Tx Nanocomposites

    Directory of Open Access Journals (Sweden)

    Changjie Shen

    2018-01-01

    Full Text Available MXene is a new type of two-dimensional layered material. Herein, a GO/Ti3C2Tx nanocomposite was prepared by a simple liquid phase method, and the obtained GO/Ti3C2Tx was transformed into RGO/Ti3C2Tx under high temperature with Ar/H2. The prepared samples were characterized using X-ray diffraction (XRD, Raman measurement, scanning electron microscopy (SEM, energy disperse spectroscopy (EDS, and X-ray photoelectron spectroscopy (XPS. As an electrode material in lithium-ion batteries, the RGO/Ti3C2Tx nanocomposite exhibited an excellent electrochemical performance and an excellent rate performance. Compared to pure Ti3C2Tx, the nanocomposite had a better reversible capacity at different current densities and had no attenuation after 200 cycles, which is one time higher than pure Ti3C2Tx. The improvement in the specific capacity was due to the excellent electrical conductivity and the unique structure of RGO, in which a charge transfer bridge was built among the Ti3C2Tx flakes. Such a bridge shortened the transmission distance of the electrons and ions and effectively controlled the restacking of the laminated materials.

  17. Synthesis and Electrochemical Studies of ReO3 Type Phase Nb3O7F

    Directory of Open Access Journals (Sweden)

    D. Saritha

    2018-04-01

    Full Text Available In latest era, explore for alternative materials to carbonaceous negative electrodes working at higher potential in lithium ion batteries is given enormous significance to avoid lithium plating and electrolyte decomposition. Niobium based oxides show enhanced results as choice to carbonaceous anodes and also Nb5+/4+ redox couple working at approximately 1.5V vs. lithium.The redox potential of the niobium metal ion (~1.5V and the structure of Nb3O7F encourage us lithium insertion studies. Nb3O7F compound has been synthesized through a simple solid state method to explore as anode material. A structural and electrochemical property of this compound is studied in detail.The charge-discharge curves are obtained galvanostatically at C/5 rate. In first discharge step, 5.3 Li can be inserted into four step process between 3.0 – 1.0 V with a specific capacity of 350 mAhg-1. Four plateaus are observed at 1.65, 1.3,1.2 and 1.1V. During charge 1.3 Li can be extracted with an irreversible capacity loss. The total first-charge capacity is 86 mAhg-1 corresponding to the extraction of 1.3 Li. These cells show a reversible capacity 86 mAhg-1 after 25 cycles. The detailed results will be described and discussed.

  18. Synthesis and Characterization of Novel Polythiophenes Containing Pyrene Chromophores: Thermal, Optical and Electrochemical Properties

    Directory of Open Access Journals (Sweden)

    Bianca X. Valderrama-García

    2016-01-01

    Full Text Available A novel series of pyrene containing thiophene monomers TPM1–5 were synthesized and fully characterized by FTIR, MS, 1H- and 13C-NMR spectroscopy; their thermal properties were determined by TGA and DSC. These monomers were chemically polymerized using FeCl3 as oxidizing agent to give the corresponding oligomers TPO1–5 and they were electrochemically polymerized to obtain the corresponding polymer films deposited onto ITO. All oligomers exhibited good thermal stability, with T10 values between 255 and 299 °C, and Tg values varying from 36 to 39 °C. The monomers showed an absorption band at 345 nm due to the S0 → S2 transition of the pyrene group, whereas the fluorescence spectra showed a broad emission band arising from the “monomer” emission at 375–420 nm. The obtained polymers exhibited two absorption bands at 244 and 354 nm, due to the polythiophene and the pyrene moieties, respectively. The fluorescence spectra of polymers showed a broad “monomer” emission at 380–420 nm followed by an intense excimer emission band at 570 nm, due to the presence of intramolecular pyrene-pyrene interactions in these compounds.

  19. Synthesis and characterization of spray deposited CZTS thin films for photo-electrochemical application

    Science.gov (United States)

    Chavda, Arvind; Patel, Biren; Mukhopadhyay, Priyanka Marathey Indrajit; Ray, Abhijit

    2018-05-01

    Cu2ZnSnS4 (CZTS) is one of the most promising light absorber materials for photovoltaic and photo-electrochemical applications. We synthesized CZTS thin films on a F:SnO2 and soda lime glass substrates by very simple, cost effective and highly scalable spray pyrolysis technique. The films were post treated by rapid thermal processing route of sulfurization to enhance the stoichiometry and crystallinity of the film. The structural, morphological, optical and electrical properties of RTP sulfurized films were studied. The X-ray diffraction (XRD) pattern revealed the formation of tetragonal CZTS phase, which confirmed by Raman analysis with a major peak at 336 cm-1 without the presence of the principle vibration mode of any other secondary phases, such as Cu2SnS3, CuxS(x=1.8,2) etc. The sulfurized film exhibited increased crystallinity and better stoichiometry. The optical and electrical data reveal the direct optical band gap, bulk carrier concentration and resistivity of 1.5 eV, 2.28×1018 cm-3 and 1.21 Ω/cm2, respectively. Finally the photoactivity of CZTS thin films was tested by forming photoelectrochemical cell in 0.1M Na2S2O3 electrolyte (pH=7.72), showing a cathodic photocurrent of nearly 20 µA/cm2 at 0V RHE.

  20. Synthesis and Electrochemical Performance of a Lithium Titanium Phosphate Anode for Aqueous Lithium-Ion Batteries

    KAUST Repository

    Wessells, Colin

    2011-01-01

    Lithium-ion batteries that use aqueous electrolytes offer safety and cost advantages when compared to today\\'s commercial cells that use organic electrolytes. The equilibrium reaction potential of lithium titanium phosphate is -0.5 V with respect to the standard hydrogen electrode, which makes this material attractive for use as a negative electrode in aqueous electrolytes. This material was synthesized using a Pechini type method. Galvanostatic cycling of the resulting lithium titanium phosphate showed an initial discharge capacity of 115 mAh/g and quite good capacity retention during cycling, 84% after 100 cycles, and 70% after 160 cycles at a 1 C cycling rate in an organic electrolyte. An initial discharge capacity of 113 mAh/g and capacity retention of 89% after 100 cycles with a coulombic efficiency above 98% was observed at a C/5 rate in pH -neutral 2 M Li2 S O4. The good cycle life and high efficiency in an aqueous electrolyte demonstrate that lithium titanium phosphate is an excellent candidate negative electrode material for use in aqueous lithium-ion batteries. © 2011 The Electrochemical Society.

  1. Continuous synthesis of colloidal silver nanoparticles by electrochemical discharge in aqueous solutions

    International Nuclear Information System (INIS)

    Tseng, Kuo-Hsiung; Chen, Yu-Chun; Shyue, Jing-Jong

    2011-01-01

    This article presents an electrochemical discharge (ECD) method that consists of a combination of chemical methods and electric arc discharges. In the method, 140 V is applied to an Ag electrode from a DC power supply. The arc-discharge between the electrodes produces metallic silver nanoparticles and silver ions in the aqueous solution. Compared with the original arc discharge, this ECD method creates smaller nanoparticles, prevents clumping of the nanoparticles, and shortens the production time. The citrate ions also reduce the silver ions to silver nanoparticles. In addition, the citrate ions cap the surface of the produced silver nanoparticles and the zeta potential increases. In this article, the weight loss of the electrodes and the reduction of silver ions to silver nanoparticles as a function of citrate concentration and electric conductivity of the medium are discussed. Furthermore, the properties of the colloidal silver prepared with ECD are analyzed by UV–Vis spectroscopy, dynamic light scattering, electrophoresis light scattering, and scanning electron microscopy. Finally, a continuous production apparatus is presented for the continuous production of colloidal silver.

  2. Sonochemical synthesis, characterization, and electrochemical properties of MnMoO4 nanorods for supercapacitor applications

    International Nuclear Information System (INIS)

    Veerasubramani, Ganesh Kumar; Krishnamoorthy, Karthikeyan; Sivaprakasam, Radhakrishnan; Kim, Sang Jae

    2014-01-01

    In this article, we reported the preparation of manganese molybdate (MnMoO 4 ) nanorods by a facile sonochemical method and investigated its electrochemical properties for supercapacitor applications. The microstructure, surface morphology and composition were characterized by using field emission scanning electron microscope (FE-SEM), high resolution-transmission electron microscopy (HR-TEM), X-ray diffraction analysis (XRD), Raman spectroscopy and X-ray photo electron microscopy (XPS). The cyclic voltammetry (CV) curves of sonochemically synthesized α-MnMoO 4 nanorods revealed the presence of redox pairs suggesting the pseudocapacitive nature of MnMoO 4 . A maximum specific capacitance of the α-MnMoO 4 nanorods was about 168.32 F g −1 as observed from the galvanostatic charge–discharge (GCD) analysis at a constant current density of 0.5 mA cm −2 . Long term cyclic stability study revealed that about 96% of initial capacitance was retained after 2000 cycles. - Highlights: • MnMoO 4 nanorods were synthesized by sonochemical method. • FE-SEM studies show the rod like morphology of MnMoO 4 . • XRD studies show the presence of monoclinic phase of α-MnMoO 4 . • Specific capacitance of 168.32 F g −1 was achieved using charge–discharge analysis

  3. Synthesis and Electrochemical Properties of LiFePO4/C for Lithium Ion Batteries.

    Science.gov (United States)

    Gao, Hong; Wang, Jiazhao; Yin, Shengyu; Zheng, Hao; Wang, Shengfu; Feng, Chuanqi; Wang, Shiquan

    2015-03-01

    LiFePO4/C was prepared through a facile rheological phase reaction method by using Fe3(PO4)2, Li3PO4 · 8H2O, and glucose as reactants. The LiFePO4/C samples were characterized by X-ray diffraction, scanning electron microscopy, and thermogravimetric analysis. The electrochemical properties of the samples were investigated. The results show that the LiFePO4/C samples have single-phase olivine-type structure, and their particles feature a spherical shape. The carbon coating on the particles of LiFePO4 is about 1.8% of the LiFePO4/C by weight. The particle size was distributed from 0.2 to 1 µm. The initial discharge capacity of LiFePO4/C reached 154 mA h/g at 0.1 C. The retained discharge capacity of LiFePO4/C was 152.9 mA h g(-1) after 50 cycles. The LiFePO4/C also showed better cycling performance than that of the bare LiPeO4 at a higher charge/discharge rate (1 C). The LIFePO4/C prepared in this way could be a promising cathode material for lithium ion battery application.

  4. 6-Aminocoumarin-naphthoquinone conjugates: design, synthesis, photophysical and electrochemical properties and DFT calculations

    Energy Technology Data Exchange (ETDEWEB)

    Miranda, Fabio S.; Ronconi, Celia M.; Sousa, Mikaelly O.B.; Silveira, Gleiciani Q.; Vargas, Maria D., E-mail: miranda@vm.uff.br, E-mail: mdvargascp@gmail.com [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Inst. de Quimica

    2014-01-15

    Four novel 6-aminocoumarin-naphthoquinone conjugates were synthesized and their photophysical and electrochemical properties, investigated. 2-Chloro-3-(2-oxo-2H-chromen-6- ylamino)-1,4-naphthoquinone 1 did not present appreciable fluorescence in solution in comparison with 6-aminocoumarin, 6-AC. In order to understand the reasons for the fluorescence quenching in this compound, two strategies were attempted. Firstly, compound 1 was N-methylated to remove the intramolecular N-H...O=C electrostatic interaction that maintained the two units fixed, but the emission properties of the product 2 were not significantly different from those of 1. Time-dependent density functional theory (TD-DFT) calculations of compounds 1 and 2 indicate that the fluorescence quenching is related to the electron acceptor character of the naphthoquinone ring. The second strategy, therefore, involved the substitution of the chlorine atom in position 2 of the naphthoquinone nucleus for different electron donor groups (compounds 3-5), but again the emission properties did not change significantly. To explain these experimental findings, TD-DFT calculations of the ground (S{sub 0}) and excited (S{sub 1}) states of all molecules in solution were carried out. The results suggest that the energy states in these conjugates are such that the fluorescent group (6-AC) donates electrons to the naphthoquinone LUMO resulting in an oxidative photoinduced electron transfer (oxidative-PET). (author)

  5. Synthesis, characterization and electrochemical performance of Al-substituted Li_2MnO_3

    International Nuclear Information System (INIS)

    Torres-Castro, Loraine; Shojan, Jifi; Julien, Christian M.; Huq, Ashfia; Dhital, Chetan; Paranthaman, Mariappan Parans; Katiyar, Ram S.; Manivannan, Ayyakkannu

    2015-01-01

    Graphical abstract: Comparison of the cycling performances for pure Li_2MnO_3 and Al-substituted Li_2MnO_3 compounds at a current density of 10 mAh g"−"1 for 100 cycles. Al-substitution increases the spinel phase and hence improves the cycling behavior. - Highlights: • Pure and Al-doped Li_2MnO_3 compounds were synthesized by a Pechini method. • Presence of monoclinic and spinel phases confirmed by Raman and Neutron diffraction. • Al substitution occurs at both Mn and Li sites in Li_2MnO_3 structure. • Al substitution reduces Mn valence state and promotes spinel phase formation. • Stable cycling capacity of 70 mAh g"−"1 was observed for nominal Li_0_._5Al_0_._5MnO_3. - Abstract: Li_2MnO_3 is known to be electrochemically inactive due to Mn in tetravalent oxidation state. Several compositions such as Li_2MnO_3, Li_1_._5Al_0_._1_7MnO_3, Li_1_._0Al_0_._3_3MnO_3 and Li_0_._5Al_0_._5MnO_3 were synthesized by a sol–gel Pechini method. All the samples were characterized with XRD, Raman, XPS, SEM, Tap density and BET analyzer. XRD patterns indicated the presence of monoclinic phase for pristine Li_2MnO_3 and mixed monoclinic/spinel phases (Li_2_−_xMn_1_−_yAl_x_+_yO_3_+_z) for Al-substituted Li_2MnO_3 compounds. The Al substitution seems to occur both at Li and Mn sites, which could explain the presence of spinel phase. XPS analysis for Mn 2p orbital reveals a significant decrease in binding energy for Li_1_._0Al_0_._3_3MnO_3 and Li_0_._5Al_0_._5MnO_3 compounds. Cyclic voltammetry, charge/discharge cycles and electrochemical impedance spectroscopy were also performed. A discharge capacity of 24 mAh g"−"1 for Li_2MnO_3, 68 mAh g"−"1 for Li_1_._5Al_0_._1_7MnO_3, 58 mAh g"−"1 for Li_1_._0Al_0_._3_3MnO_3 and 74 mAh g"−"1 for Li_0_._5Al_0_._5MnO_3 were obtained. Aluminum substitutions increased the formation of spinel phase which is responsible for cycling.

  6. Hexagonal nanorods of tungsten trioxide: Synthesis, structure, electrochemical properties and activity as supporting material in electrocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Salmaoui, Samiha; Sediri, Faouzi; Gharbi, Neji [Laboratoire de Chimie de la Matiere Condensee, Institut Preparatoire aux Etudes d' Ingenieurs, Universite de Tunis (Tunisia); Perruchot, Christian; Aeiyach, Salah [Interfaces, Traitements, Organisation et DYnamique des Systemes (ITODYS), UMR 7086, Universite Paris Diderot Paris 7, 15, rue Jean de Baif, 75205 Paris Cedex 13 (France); Rutkowska, Iwona A.; Kulesza, Pawel J. [Department of Chemistry, University of Warsaw, Pasteura 1, PL-02-093 Warsaw (Poland); Jouini, Mohamed, E-mail: jouini@univ-paris-diderot.fr [Interfaces, Traitements, Organisation et DYnamique des Systemes (ITODYS), UMR 7086, Universite Paris Diderot Paris 7, 15, rue Jean de Baif, 75205 Paris Cedex 13 (France)

    2011-07-15

    Tungsten trioxide, unhydrated with hexagonal structure (h-WO{sub 3}), has been prepared by hydrothermal method at a temperature of 180 {sup o}C in acidified sodium tungstate solution. Thus prepared h-WO{sub 3} has been characterized by X-ray diffraction (XRD) method and using electrochemical techniques. The morphology has been examined by scanning and transmission electron microscopies (SEM and TEM) and it is consistent with existence of nanorods of 50-70 nm diameter and up to 5 {mu}m length. Cyclic voltammetric characterization of thin films of h-WO{sub 3} nanorods has revealed reversible redox behaviour with charge-discharge cycling corresponding to the reversible lithium intercalation/deintercalation into the crystal lattice of the h-WO{sub 3} nanorods. In propylene carbonate containing LiClO{sub 4}, two successive redox processes of hexagonal WO{sub 3} nanorods are observed at the scan rate of 50 mV/s. Such behaviour shall be attributed to the presence of at least two W atoms of different surroundings in the lattice structure of h-WO{sub 3} nanorods. On the other hand, in aqueous LiClO{sub 4} solution, only one redox process is observed at the scan rate of 10 mV/s. The above observations can be explained in terms of differences in the diffusion of ions inside two types of channel cavities existing in the structure of the h-WO{sub 3} nanorods. Moreover, the material can be applied as active support for the catalytic bi-metallic Pt-Ru nanoparticles during electrooxidation of ethanol in acid medium (0.5 mol dm{sup -3} H{sub 2}SO{sub 4}).

  7. Synthesis of tantalum carbide and nitride nanoparticles using a reactive mesoporous template for electrochemical hydrogen evolution

    KAUST Repository

    Alhajri, Nawal Saad; Yoshida, Hiroshi; Anjum, Dalaver H.; Garcia Esparza, Angel T.; Kubota, Jun; Domen, Kazunari; Takanabe, Kazuhiro

    2013-01-01

    Tantalum carbide and nitride nanocrystals were prepared through the reaction of a tantalum precursor with mesoporous graphitic (mpg)-C 3N4. The effects of the reaction temperature, the ratio of the Ta precursor to the reactive template (mpg-C3N4), and the selection of the carrier gas (Ar, N2 and NH3) on the resultant crystal phases and structures were investigated. The produced samples were characterized using powder X-ray diffraction (XRD), CHN elemental analyses, thermogravimetric analyses (TGA), nitrogen sorption, a temperature-programmed reaction with mass spectroscopy (MS), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The results indicate that the different tantalum phases with cubic structure, TaN, Ta2CN, and TaC, can be formed under a flow of nitrogen when formed at different temperatures. The Ta3N5 phase with a Ta5+ oxidation state was solely obtained at 1023 K under a flow of ammonia, which gasified the C 3N4 template and was confirmed by detecting the decomposed gaseous products via MS. Significantly, the formation of TaC, Ta2CN, and TaN can be controlled by altering the weight ratio of the C 3N4 template relative to the Ta precursor at 1573 K under a flow of nitrogen. The high C3N4/Ta precursor ratio generally resulted in high carbide content rather than a nitride one, consistent with the role of mpg-C3N4 as a carbon source. Electrochemical measurements revealed that the synthesized nanomaterials were consistently able to produce hydrogen under acidic conditions (pH 1). The obtained Tafel slope indicates that the rate-determining step is the Volmer discharge step, which is consistent with adsorbed hydrogen being weakly bound to the surface during electrocatalysis. © 2013 The Royal Society of Chemistry.

  8. Hexagonal nanorods of tungsten trioxide: Synthesis, structure, electrochemical properties and activity as supporting material in electrocatalysis

    International Nuclear Information System (INIS)

    Salmaoui, Samiha; Sediri, Faouzi; Gharbi, Neji; Perruchot, Christian; Aeiyach, Salah; Rutkowska, Iwona A.; Kulesza, Pawel J.; Jouini, Mohamed

    2011-01-01

    Tungsten trioxide, unhydrated with hexagonal structure (h-WO 3 ), has been prepared by hydrothermal method at a temperature of 180 o C in acidified sodium tungstate solution. Thus prepared h-WO 3 has been characterized by X-ray diffraction (XRD) method and using electrochemical techniques. The morphology has been examined by scanning and transmission electron microscopies (SEM and TEM) and it is consistent with existence of nanorods of 50-70 nm diameter and up to 5 μm length. Cyclic voltammetric characterization of thin films of h-WO 3 nanorods has revealed reversible redox behaviour with charge-discharge cycling corresponding to the reversible lithium intercalation/deintercalation into the crystal lattice of the h-WO 3 nanorods. In propylene carbonate containing LiClO 4 , two successive redox processes of hexagonal WO 3 nanorods are observed at the scan rate of 50 mV/s. Such behaviour shall be attributed to the presence of at least two W atoms of different surroundings in the lattice structure of h-WO 3 nanorods. On the other hand, in aqueous LiClO 4 solution, only one redox process is observed at the scan rate of 10 mV/s. The above observations can be explained in terms of differences in the diffusion of ions inside two types of channel cavities existing in the structure of the h-WO 3 nanorods. Moreover, the material can be applied as active support for the catalytic bi-metallic Pt-Ru nanoparticles during electrooxidation of ethanol in acid medium (0.5 mol dm -3 H 2 SO 4 ).

  9. Hexagonal nanorods of tungsten trioxide: Synthesis, structure, electrochemical properties and activity as supporting material in electrocatalysis

    Science.gov (United States)

    Salmaoui, Samiha; Sediri, Faouzi; Gharbi, Néji; Perruchot, Christian; Aeiyach, Salah; Rutkowska, Iwona A.; Kulesza, Pawel J.; Jouini, Mohamed

    2011-07-01

    Tungsten trioxide, unhydrated with hexagonal structure (h-WO 3), has been prepared by hydrothermal method at a temperature of 180 °C in acidified sodium tungstate solution. Thus prepared h-WO 3 has been characterized by X-ray diffraction (XRD) method and using electrochemical techniques. The morphology has been examined by scanning and transmission electron microscopies (SEM and TEM) and it is consistent with existence of nanorods of 50-70 nm diameter and up to 5 μm length. Cyclic voltammetric characterization of thin films of h-WO 3 nanorods has revealed reversible redox behaviour with charge-discharge cycling corresponding to the reversible lithium intercalation/deintercalation into the crystal lattice of the h-WO 3 nanorods. In propylene carbonate containing LiClO 4, two successive redox processes of hexagonal WO 3 nanorods are observed at the scan rate of 50 mV/s. Such behaviour shall be attributed to the presence of at least two W atoms of different surroundings in the lattice structure of h-WO 3 nanorods. On the other hand, in aqueous LiClO 4 solution, only one redox process is observed at the scan rate of 10 mV/s. The above observations can be explained in terms of differences in the diffusion of ions inside two types of channel cavities existing in the structure of the h-WO 3 nanorods. Moreover, the material can be applied as active support for the catalytic bi-metallic Pt-Ru nanoparticles during electrooxidation of ethanol in acid medium (0.5 mol dm -3 H 2SO 4).

  10. Synthesis, crystal structure and electrochemical and DNA binding studies of oxygen bridged-copper(II) carboxylate

    Science.gov (United States)

    Iqbal, Muhammad; Ali, Saqib; Tahir, Muhammad Nawaz; Muhammad, Niaz; Shah, Naseer Ali; Sohail, Manzar; Pandarinathan, Vedapriya

    2015-08-01

    A new binuclear O-bridged Cu(II) complex with 4-chlorophenyl acetate and 2,2‧-bipyridine has been synthesized and characterized using FT-IR, powder and single crystal XRD and electrochemical solution studies. The results revealed that the two penta-coordinated Cu(II) centers are linked by two carboxylate ligands in end-on bonding fashion. The coordination geometry is slightly distorted square pyramidal (SP) with bridging oxygen atoms occupying the apical position and other ligands lying in the equatorial plane. The striking difference in Cu-O bond distance of the bridging oxygen atom in the complex may be responsible for the SP geometry of Cu(II) ion. The complex gave rise to metal centered irreversible electro-activity where one electron Cu(II)/Cu(III) oxidation process and a single step two electron Cu(II)/Cu(0) reduction process was observed. The redox processes were found predominantly adsorption controlled. The values of diffusion coefficient and heterogeneous rate constant for oxidation process were 6.98 × 10-7 cm2 s-1 and 4.60 × 10-5 cm s-1 while the corresponding values for reduction were 5.30 × 10-8 cm2 s-1 and 5.41 × 10-6 cm s-1, respectively. The formal potential and charge transfer coefficient were also calculated. The DNA-binding ability was explored through cyclic voltammetry and UV-Visible spectroscopy. Diminution in the value of Do for oxidation indicated the binding of the complex with DNA corresponding to Kb = 8.58 × 104 M-1. UV-Visible spectroscopy yielded ε = 49 L mol-1 cm-1 and Kb = 2.96 × 104 M-1. The data of both techniques support each other. The self-induced redox activation of the complex, as indicated by cyclic voltammetry heralds its potential applications in redox catalysis and anticancer activity.

  11. Anderson-Type Polyoxometalates Functionalized by Tetrathiafulvalene Groups: Synthesis, Electrochemical Studies, and NLO Properties.

    Science.gov (United States)

    Boulmier, Amandine; Vacher, Antoine; Zang, Dejin; Yang, Shu; Saad, Ali; Marrot, Jérôme; Oms, Olivier; Mialane, Pierre; Ledoux, Isabelle; Ruhlmann, Laurent; Lorcy, Dominique; Dolbecq, Anne

    2018-04-02

    Three polyoxometalates (POMs) functionalized by tetrathiafulvalene (TTF) molecules have been synthesized by a coupling reaction between the Anderson-type POMs [MnMo 6 O 18 {(OCH 2 ) 3 CNH 2 } 2 ] 3- or [AlMo 6 O 18 (OH) 3 {(OCH 2 ) 3 CNH 2 }] 3- and the TTF carboxylic acid derivative (MeS) 3 TTF(S-CH 2 -CO 2 H). The monofunctionalized TTF-AlMo 6 POM contains one TTF group covalently grafted on an Al Anderson platform. The symmetrical TTF-MnMo 6 -TTF POM possesses two TTF groups grafted on each side of a Mn Anderson derivative while the asymmetrical TTF-MnMo 6 -SP POM contains a TTF and a spiropyran groups. These three trianionic species have been characterized by elemental analysis, 1 H and 13 C NMR, FT-IR spectroscopy, ESI-MS spectrometry, and single-crystal X-ray diffraction (for TTF-MnMo 6 -TTF). In the solid state, the grafted TTF molecules of TTF-MnMo 6 -TTF POMs interact via S···S and π···π interactions and form chains. The electrochemical properties of the complexes reflect the contributions of both the inorganic POM and the TTF moieties. Despite adsorption of the oxidized hybrid species on the Pt grid working electrode, UV-vis-NIR spectroelectrochemical investigations evidence peaks characteristic of the oxidation of the TTF units. Finally, hyper-Rayleigh scattering (HRS) measurements show that the three novel TTF derivatives exhibit β values between 20 and 37 × 10 -30 esu. Moreover it is observed that the oxidation of the TTF moieties by Fe 3+ ions increases the NLO response. These values are in the order of magnitude of that found for the well-known 4-dimethylamino- N-methyl-4-stilbazolium (DAS + ) cation (β = 60 × 10 -30 esu).

  12. Synthesis and transport characterization of electrochemically deposited CdTe nanowires

    Science.gov (United States)

    Kaur, Jaskiran; Kaur, Harmanmeet; Singh, R. C.

    2018-04-01

    This paper reports the synthesis and characterization of CdTe nanowires. A thin polymeric films were irradiated with 80MeV Ag ions at a fluence of 8E7 ions/cm2, followed by UV irradiation and chemically etching in aqueous NaOH. Nanosizes go-through pores so formed were filled using a specially designed cell via electrodeposition. Nanowires so formed were further studied using SEM, I-V, UV and XRD analysis. SEM images show very smooth and uniform CdTe nanowires freely standing on the substrate. The in-situ I-V characteristics of nano-/micro structures was carried out at room temperature by leaving the structures embedded in the insulating template membrane itself.

  13. Sonochemical synthesis of nanostructured nickel hydroxide as an electrode material for improved electrochemical energy storage application

    Directory of Open Access Journals (Sweden)

    Arshid Numan

    2017-08-01

    Full Text Available A facile and fast approach for the synthesis of a nanostructured nickel hydroxide (Ni(OH2 via sonochemical technique is reported in the present study. The X-ray diffraction results confirmed that the synthesized Ni(OH2 was oriented in β-phase of hexagonal brucite structure. The nanostructured Ni(OH2 electrode exhibited the maximum specific capacitance of 1256 F/g at a current density of 200 mA/g in 1 M KOH(aq. Ni(OH2 electrodes exhibited the pseudocapacitive behavior due to the presence of redox reaction. It also exhibited long-term cyclic stability of 85% after 2000 cycles, suggesting that the nanostructured Ni(OH2 electrode will play a promising role for high performance supercapacitor application.

  14. Electrochemical synthesis of metallic microstructures using etched ion tracks in nuclear track filters

    International Nuclear Information System (INIS)

    Sanjeev Kumar; Shyam Kumar; Rajesh Kumar; Chakravarti, K.

    2004-01-01

    Interest in nano/microstructures results from their numerous potential applications in various areas such as materials and biomedical sciences, electronics, optics, magnetism, energy storage and electrochemistry. Materials with micro/nanoscopic dimensions not only have potential technological applications in areas such as device technology and drug delivery, but also are of fundamental interest in that the properties of a material can change in this regime of transition between the bulk and molecular scales. Electrodeposition is a versatile technique combining low processing cost with ambient conditions that can be used to prepare metallic, polymeric and semiconducting microstructures. In the present work ion track membranes of Makrofol (KG) have been used as templates for synthesis of metallic microstructures using the technique of electrodeposition. (author)

  15. Morphology-Controlled Synthesis of Hematite Nanocrystals and Their Optical, Magnetic and Electrochemical Performance

    Science.gov (United States)

    Li, Bangquan; Sun, Qian; Fan, Hongsheng; Cheng, Ming; Shan, Aixian; Cui, Yimin; Wang, Rongming

    2018-01-01

    A series of α-Fe2O3 nanocrystals (NCs) with fascinating morphologies, such as hollow nanoolives, nanotubes, nanospindles, and nanoplates, were prepared through a simple template-free hydrothermal synthesis process. The results showed that the morphologies could be easily controlled by SO42− and H2PO4−. Physical property analysis showed that the α-Fe2O3 NCs exhibited shape- and size-dependent ferromagnetic and optical behaviors. The absorption band peak of the α-Fe2O3 NCs could be tuned from 320 to 610 nm. Furthermore, when applied as electrode material for supercapacitor, the hollow olive-structure exhibited the highest capacitance (285.9 F·g−1) and an excellent long-term cycling stability (93% after 3000 cycles), indicating that it could serve as a candidate electrode material for a supercapacitor. PMID:29342929

  16. Characterization and electrochemical performances of MoO2 modified LiFePO4/C cathode materials synthesized by in situ synthesis method

    International Nuclear Information System (INIS)

    He, Jichuan; Wang, Haibin; Gu, Chunlei; Liu, Shuxin

    2014-01-01

    Graphical abstract: The MoO 2 modified LiFePO 4 /C cathode materials were synthesized by in situ synthesis method. MoO 2 can sufficiently coat on the LiFePO 4 /C particles surface and does not alter LiFePO 4 crystal structure, and the adding of MoO 2 decreases the particles size and increases the tap density of cathode materials. The existence of MoO 2 improves electrochemical performance of LiFePO 4 cathode materials in specific capability and lithium ion diffusion and charge transfer resistance of cathode materials. - Highlights: • The MoO 2 modified LiFePO 4 /C cathode materials were synthesized by in situ synthesis method. • The existence of MoO 2 decreases the particles size and increases the tap density of cathode materials. • MoO 2 can sufficiently coat on the surface of LiFePO 4 /C cathode materials. • The existence of MoO 2 enhanced electrochemical performance of LiFePO 4 /C cathode materials. - Abstract: The MoO 2 modified LiFePO 4 /C cathode materials were synthesized by in situ synthesis method. Phase compositions and microstructures of the products were characterized by X-ray powder diffraction (XRD), SEM, TEM and EDS. Results indicate that MoO 2 can sufficiently coat on the LiFePO 4 surface and does not alter LiFePO 4 crystal structure, the existence of MoO 2 decreases the particles size and increases the tap density of cathode materials. The electrochemical behavior of cathode materials was analyzed using galvanostatic measurement, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results show that the existence of MoO 2 improves electrochemical performance of LiFePO 4 cathode materials in specific capability and lithium ion diffusion and charge transfer resistance. The initial charge–discharge specific capacity and apparent lithium ion diffusion coefficient increase, the charge transfer resistance decreases with MoO 2 content and maximizes around the MoO 2 content is 5 wt%. It has been had further proved that

  17. Spectral characterization of a newly synthesized fluorescent semicarbazone derivative and its usage as a selective fiber optic sensor for copper(II).

    Science.gov (United States)

    Oter, Ozlem; Ertekin, Kadriye; Kirilmis, Cumhur; Koca, Murat

    2007-02-19

    In this work photoluminescent properties of highly Cu(2+) selective organic fluoroionophore, semicarbazone derivative; bis(naphtho[2,1-b]furan-2-yl)methanone semicarbazone (BNF) was investigated in different solvents (dichloromethane, tetrahydrofuran, toluene and ethanol) and in polymer matrices of polyvinylchloride (PVC) and ethyl cellulose (EC) by absorption and emission spectrometry. The BNF derivative displayed enhanced fluorescence emission quantum yield, Q(f)=6.1 x 10(-2) and molar extinction coefficient, epsilon=29,000+/-65 cm(-1)M(-1) in immobilized PVC matrix, compared to 2.6 x 10(-3) and 24,573+/-115 in ethanol solution. The offered sensor exhibited remarkable fluorescence intensity quenching upon exposure to Cu(2+) ions at pH 4.0 in the concentration range of 1.0 x 10(-9) to 3.0 x 10(-4)M [Cu(2+)] while the effects of the responding ions (Ca(2+), Hg(+), Pb(2+), Al(3+), Cr(3+), Mn(2+), Mg(2+), Sn(2+), Cd(2+), Co(2+) and Ni(2+)) were less pronounced.

  18. Study of the aqueous synthesis, optical and electrochemical characterization of alloyed Zn{sub x}Cd{sub 1-x}Te nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Matos, Charlene Regina Santos [Postgraduate Program in Materials Science and Engineering, Federal University of Sergipe, São Cristóvão, SE (Brazil); Candido, Luan P.M.; Souza, Helio Oliveira [Department of Chemistry, Federal University of Sergipe, São Cristóvão, SE (Brazil); Pereira da Costa, Luiz [Institute of Technology and Research (ITP), Tiradentes University, Aracaju, SE (Brazil); Sussuchi, Eliana Midori [Department of Chemistry, Federal University of Sergipe, São Cristóvão, SE (Brazil); Gimenez, Iara F., E-mail: gimenez@ufs.br [Postgraduate Program in Materials Science and Engineering, Federal University of Sergipe, São Cristóvão, SE (Brazil); Department of Chemistry, Federal University of Sergipe, São Cristóvão, SE (Brazil); Postgraduate Program in Chemistry, Federal University of Sergipe, São Cristóvão, SE (Brazil)

    2016-08-01

    The effects of experimental factors such as initial reaction pH, capping ligand, and heating method on the optical and electrochemical properties of aqueous alloyed Zn{sub x}Cd{sub 1-x}Te nanocrystals were evaluated. Here the type of capping ligand (glutathione GSH and 3-mercaptopropionic acid MPA) was found to be the most significant factor in controlling the range of photoluminescence emission. Also a pronounced pH effect on the emission wavelength has been verified in the presence of GSH, in contrast to MPA for which only a minor pH effect was observed. The heating method (microwave or hydrothermal) was found to be irrelevant for the emission wavelength at the conditions studied. The electrochemical characterization in aqueous medium (cyclic voltammetry and differential pulse voltammetry) evidenced a good correlation between electrochemical and optical band gap values and allowed estimation of band edge positions. - Highlights: • ZnCdTe quantum dots were obtained by aqueous synthesis. • Nature of capping ligand was the most relevant factor. • Optical and electrochemical band gaps were well correlated.

  19. Octa- and nonanuclear nickel(II) polyoxometalate clusters: synthesis and electrochemical and magnetic characterizations.

    Science.gov (United States)

    Pichon, Céline; Mialane, Pierre; Dolbecq, Anne; Marrot, Jérôme; Rivière, Eric; Bassil, Bassem S; Kortz, Ulrich; Keita, Bineta; Nadjo, Louis; Sécheresse, Francis

    2008-12-01

    Three high-nuclearity NiII-substituted polyoxometalate compounds functionalized by exogenous ligands have been synthesized and characterized. The octanuclear complexes in Na15[Na{(A-R-SiW9O34)Ni4(CH3COO)3(OH)3}2] . 4NaCl . 36H2O (1) and Na15[Na{(A-R-SiW9O34)Ni4(CH3COO)3(OH)2(N3)}2] . 32H2O (2) can be described as two {Ni4} subunits connected via a {Na(CH3COO)6} group, with the acetato ligands also ensuring in each subunit the connection between the paramagnetic centers. In 2, two azido groups replace two of the six mu-hydroxo ligands present in 1. The nonanuclear complex K7Na7[(A-R-SiW9O34)2Ni9(OH)6(H2O)6(CO3)3] . 42H2O (3) exhibits a double cubanestructure with two [(A-R-SiW9O34)Ni4(OH)3]5- subunits linked by three carbonato ligands. A ninth NiII center connected to one subunit via a carbonato ligand and a O=W group completes this asymmetric polyoxometalate.Electronic spectroscopy and electrochemical studies indicate that, while compounds 1-3 decompose in a pure aqueous medium, these complexes are very stable in a pH 6 acetate medium. The cyclic voltammetry pattern of each complex is constituted by a first eight-electron reduction wave followed by a second large-current intensity wave. The characteristics of the first waves of the complexes are clearly distinct from those obtained for their lacunary precursor [A-R-SiW9O34]10-, a feature that is due to the Ni centers in the complexes. Such observations of electroactive, stable, and highly nickel-rich polyoxometalates are not common. Measurements of the magnetic susceptibility revealed the occurrence of concomitant ferromagnetic and antiferromagnetic interactions in 1 and 3.For both of these compounds, the extension of the magnetic exchange has been determined by means of a spin Hamiltonian with three and four J constants, respectively.

  20. Synthesis and characterization of electrochemically deposited nanocrystalline CdTe thin films

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Ragini Raj, E-mail: raginirajsingh@gmail.com [Department of Physics, Bhopal University, Bhopal-462026 (India); Department of Physical Electronics, Iby and Aladar Fleishman Faculty of Engineering, Tel-Aviv University, Tel-Aviv-69978 (Israel); Painuly, Diksha [Centre for Nanoscience and Nanotechnology, University of Kerala, Thiruanantpuram, Kerala (India); Pandey, R.K. [Department of Physics, Bhopal University, Bhopal-462026 (India)

    2009-07-15

    Electrodeposition is emerging as a method for the synthesis of semiconductor thin films and nanostructures. In this work we prepared the nanocrystalline CdTe thin films on indium tin oxide coated glass substrate from aqueous acidic bath at the deposition temperature 50 {+-} 1 deg. C. The films were grown potentiostatically from -0.60 V to -0.82 V with respect to saturated calomel reference electrode. The structural, compositional, morphological and optical properties were investigated using X-ray diffraction (XRD), energy dispersive analysis by X-rays (EDAX), atomic force microscopy (AFM), and UV-vis spectroscopy respectively and cyclic voltammetery. The structural and optical studies revealed that films are nanocrystalline in nature and possess cubic phase, also the films are preferentially oriented along the cubic (1 1 1) plane. The effect of cadmium composition on the deposited morphology was also investigated. The size dependent blue shift in the experimentally determined absorption edge has been compared with the theoretical predictions based on the effective mass approximation and tight binding approximation. It is shown that the experimentally determined absorption edges depart from the theoretically calculated values.

  1. Design, synthesis and structure of new potential electrochemically active boronic acid-based glucose sensors

    DEFF Research Database (Denmark)

    Norrild, Jens Chr.; Søtofte, Inger

    2002-01-01

    In the course of our investigations on new boronic acid based carbohydrate sensors three new boronic acids 3, 7 and 11 containing a ferrocene moiety were synthesised. Their design includes an intramolecular B-N bonding motif in order to facilitate binding at physiological pH. We report the synthe......In the course of our investigations on new boronic acid based carbohydrate sensors three new boronic acids 3, 7 and 11 containing a ferrocene moiety were synthesised. Their design includes an intramolecular B-N bonding motif in order to facilitate binding at physiological pH. We report...... the synthesis of the compounds and our investigations on glucose complexation as studied by C-13 NMR spectroscopy. The crystal structure of 2,4,6-tris[2-(N-ferrocenylmethyl-N-methylaminomethyl) phenyl] boroxin (13) (boroxin of boronic acid 3) (boroxin = cyclotriboroxane) was obtained and compared...... with structures obtained of 2,4,6-tris[2-(N,N-dimethylaminomethyl)phenyl]boroxin (14) and 2,2-dimethyl-1,3-diyl[2-(N,N-dimethylaminomethyl)phenyl]boronate (15). The structure of 13 shows the existence of intramolecular B-N bonds in the solid phase....

  2. Electrochemical synthesis and characterization of zinc carbonate and zinc oxide nanoparticles

    Science.gov (United States)

    Pourmortazavi, Seied Mahdi; Marashianpour, Zahra; Karimi, Meisam Sadeghpour; Mohammad-Zadeh, Mohammad

    2015-11-01

    Zinc oxide and its precursor i.e., zinc carbonate is widely utilized in various fields of industry, especially in solar energy conversion, optical, and inorganic pigments. In this work, a facile and clean electrodeposition method was utilized for the synthesis of zinc carbonate nanoparticles. Also, zinc oxide nanoparticles were produced by calcination of the prepared zinc carbonate powder. Zinc carbonate nanoparticles with different sizes were electrodeposited by electrolysis of a zinc plate as anode in the solution of sodium carbonate. It was found that the particle size of zinc carbonate might be tuned by process parameters, i.e., electrolysis voltage, carbonate ion concentration, solvent composition and stirring rate of the electrolyte solution. An orthogonal array design was utilized to identify the optimum experimental conditions. The experimental results showed that the minimum size of the electrodeposited ZnCO3 particles is about 24 nm whereas the maximum particle size is around 40 nm. The TG-DSC studies of the nanoparticles indicated that the main thermal degradation of ZnCO3 occurs in two steps over the temperature ranges of 150-250 and 350-400 °C. The electrosynthesized ZnCO3 nanoparticles were calcined at the temperature of 600 °C to prepare ZnO nanoparticles. The prepared ZnCO3 and ZnO nanoparticles were characterized by SEM, X-ray diffraction (XRD), and FT-IR techniques.

  3. Solvothermal synthesis and electrochemical performance of Li2MnSiO4/C cathode materials for lithium ion batteries

    International Nuclear Information System (INIS)

    Wang, Yan-Chao; Zhao, Shi-Xi; Zhai, Peng-Yuan; Li, Fang; Nan, Ce-Wen

    2014-01-01

    Highlights: • Li 2 MnSiO 4 /C nanocomposite has been synthesized by the solvothermal method. • The particles of Li 2 MnSiO 4 /C are much smaller and more uniform. • The presence of Ni improves discharge capacity of Li 2 MnSiO 4 /C cathode material. • The initial discharge capacity of Ni-modified Li 2 MnSiO 4 /C is 274.5 mAh g −1 at 25 °C. - Abstract: Orthorhombic structure Li 2 MnSiO 4 /C with Pmn2 1 space group is synthesized by the solvothermal method. Carbon coating and Ni 2+ doping are used to improve the electronic conductivity and the cycling performance of Li 2 MnSiO 4 cathode material, respectively. The particles of Li 2 MnSiO 4 /C are much smaller and more uniform than those of Li 2 MnSiO 4 due to the carbon coating. It is shown that Ni 2+ has been reduced into metal Ni during the synthesis process. The synthesized Ni-modified Li 2 MnSiO 4 /C (denoted as (LMS@Ni)/C) cathode material exhibits better electrochemical performance in comparison with Li 2 MnSiO 4 /C, attributing to higher lithium ion diffusion coefficient as well as electronic conductivity. The initial discharge capacity of (LMS@Ni)/C is 274.5 mA h g −1 and the reversible capacity after 20 cycles is 119.8 mA h g −1 at 25 °C

  4. Organic-inorganic hybrid polymer electrolytes based on polyether diamine, alkoxysilane, and trichlorotriazine: Synthesis, characterization, and electrochemical applications

    Science.gov (United States)

    Saikia, Diganta; Wu, Cheng-Gang; Fang, Jason; Tsai, Li-Duan; Kao, Hsien-Ming

    2014-12-01

    A new type of highly conductive organic-inorganic hybrid polymer electrolytes has been synthesized by the reaction of poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol) bis(2-aminopropyl ether), 2,4,6-trichloro-1,3,5-triazine and alkoxysilane precursor 3-(glycidyloxypropyl)trimethoxysilane, followed by doping of LiClO4. The 13C and 29Si solid-sate NMR results confirm the successful synthesis of the organic-inorganic hybrid structure. The solid hybrid electrolyte thus obtained exhibits a maximum ionic conductivity of 1.6 × 10-4 S cm-1 at 30 °C, which is the highest among the organic-inorganic hybrid electrolytes. The hybrid electrolytes are electrochemically stable up to 4.2 V. The prototype electrochromic device with such a solid hybrid electrolyte demonstrates a good coloration efficiency value of 183 cm2 C-1 with a cycle life over 200 cycles. For the lithium-ion battery test, the salt free solid hybrid membrane is swelled with a LiPF6-containing electrolyte solution to reach an acceptable ionic conductivity value of 6.5 × 10-3 S cm-1 at 30 °C. The battery cell carries an initial discharge capacity of 100 mAh g-1 at 0.2C-rate and a coulombic efficiency of about 95% up to 30 cycles without the sign of cell failure. The present organic-inorganic hybrid electrolytes hold promise for applications in electrochromic devices and lithium ion batteries.

  5. Synthesis, characterization and electrochemical properties of the V2O5.nH2O/AlO(OH).nH2O xerogel composite

    International Nuclear Information System (INIS)

    Zampronio, Elaine C.; Lassali, Tania A.F.; Oliveira, Herenilton P.

    2005-01-01

    In this work, we report the synthesis, characterization and electrochemical properties of a new multicomponent material obtained from the polymerization of vanadium pentoxide in an inorganic matrix (alumina xerogel), forming a xerogel composite. The material has been characterized by X-ray diffraction, infrared spectroscopy, thermogravimetric analysis, electron microscopy, energy dispersive X-ray spectrometry, cyclic voltammetry and impedance spectroscopy. It was found that the V 2 O 5 xerogel is dispersed in the alumina matrix, but its lamellar structure is not strongly affected, thus, its conductivity properties are maintained. Moreover, the electrochemical behaviour of the V 2 O 5 xerogel dispersed in the alumina matrix is quite similar to that found for the V 2 O 5 xerogel alone and the inorganic matrix leads to stabilization of V 2 O 5 xerogel structure

  6. Synthesis of CdS flower-like hierarchical microspheres as electrode material for electrochemical performance

    International Nuclear Information System (INIS)

    Kaviyarasu, K.; Manikandan, E.; Maaza, M.

    2015-01-01

    We report in this paper, a facile hydrothermal route for the preparation of CdS nanocrystals at room temperature (RT). Composition, structure and morphology of the products were analyzed and characterized by X-ray diffraction (XRD) confirms that the hydrothermal treatment at 180 °C for periods ranging from 0 to 1440 min caused no significant modification of the long range order structure subjected to hydrothermal treatment. From the XRD analysis the diffraction peaks pertaining to 26.75°, 43.89° and 52.34° are attributed to the (111), (220) and (311) planes of cubic zinc blende structure. The Photoluminescence (PL) spectra are dominated by a strong narrow band edge emission tunable in the blue region of the visible spectra indicating the narrow size distribution of CdS nanocrystals. TEM observation shows that the CdS nanocrystals synthesized by hydrothermal synthesis are well dispersed and the average crystallite size was found to be ∼10 nm. The confocal microscopic studies reveal that each flower like spheres is due to Ostwald's ripening with numerous nanoparticles aggregating a surface. - Highlights: • The adjacent particle coalesces together forming spherical particles. • The average crystalline size of CdS nanoparticles was found to be ∼3 nm. • In the case of spherical crystallite, is given by L = 3/4 D. • The CdS nanocrystal exhibits a direct band gap of 2.4 eV. • The microspheres are dispersed with good monodispersity

  7. Synthesis of TiO2 by electrochemical method from TiCl4 solution as anode material for lithium-ion batteries

    International Nuclear Information System (INIS)

    Nur, Adrian; Purwanto, Agus; Jumari, Arif; Dyartanti, Endah R.; Sari, Sifa Dian Permata; Hanifah, Ita Nur

    2016-01-01

    Metal oxide combined with graphite becomes interesting composition. TiO 2 is a good candidate for Li ion battery anode because of cost, availability of sufficient materials, and environmentally friendly. TiO 2 gravimetric capacity varied within a fairly wide range. TiO 2 crystals form highly depends on the synthesis method used. The electrochemical method is beginning to emerge as a valuable option for preparing TiO 2 powders. Using the electrochemical method, the particle can easily be controlled by simply adjusting the imposed current or potential to the system. In this work, the effects of some key parameters of the electrosynthesis on the formation of TiO 2 have been investigated. The combination of graphite and TiO 2 particle has also been studied for lithium-ion batteries. The homogeneous solution for the electrosynthesis of TiO 2 powders was TiCl 4 in ethanol solution. The electrolysis was carried out in an electrochemical cell consisting of two carbon electrodes with dimensions of (5 × 2) cm. The electrodes were set parallel with a distance of 2.6 cm between the electrodes and immersed in the electrolytic solution at a depth of 2 cm. The electrodes were connected to the positive and negative terminals of a DC power supply. The electrosynthesis was performed galvanostatically at 0.5 to 2.5 hours and voltages were varied from 8 to 12 V under constant stirring at room temperature. The resulted suspension was aged at 48 hrs, filtered, dried directly in an oven at 150°C for 2 hrs, washed 2 times, and dried again 60 °C for 6 hrs. The particle product has been used to lithium-ion battery as anode. Synthesis of TiO 2 particle by electrochemical method at 10 V for 1 to 2.5 hrs resulted anatase and rutile phase

  8. Lithium-deficient Li YMn2O4 spinels (0.9 ≤ Y < 1): Lithium content, synthesis temperature, thermal behaviour and electrochemical properties

    International Nuclear Information System (INIS)

    Pascual, Laura; Perez-Revenga, M. Luz; Rojas, Rosa M.; Rojo, Jose M.; Amarilla, J. Manuel

    2006-01-01

    Lithium-deficient Li Y Mn 2 O 4 spinels (LD-Li Y Mn 2 O 4 ) with nominal composition (0.9 ≤ Y 2 O 3 and LiNO 3 at temperatures ranging from 700 deg. C to 850 deg. C. X-ray diffraction data show that LD-Li Y Mn 2 O 4 spinels are obtained as single phases in the range Y = 0.975-1 at 700 deg. C and 750 deg. C. Morphological characterization by transmission electron microscopy shows that the particle size of LD-Li Y Mn 2 O 4 spinels increases on decreasing the Li-content. The influence of the Li-content and the synthesis temperature on the thermal and electrochemical behaviours has been systematically studied. Thermal analysis studies indicate that the temperature of the first thermal effect in the differential thermal analysis (DTA)/thermogravimetric (TG) curves, T C1 , linearly increases on decreasing the Li-content. The electrochemical properties of LD-Li Y Mn 2 O 4 spinels, determined by galvanostatic cycling, notably change with the synthesis conditions. So, the first discharge capacity, Q disch. , at C rate increases on rising the Li-content and the synthesis temperature. The sample Li 0.975 Mn 2 O 4 synthesized at 700 deg. C has a Q disch. = 123 mAh g -1 and a capacity retention of 99.77% per cycle. This LD-Li Y Mn 2 O 4 sample had the best electrochemical characteristics of the series

  9. Semicarbazone EGA Inhibits Uptake of Diphtheria Toxin into Human Cells and Protects Cells from Intoxication

    Directory of Open Access Journals (Sweden)

    Leonie Schnell

    2016-07-01

    Full Text Available Diphtheria toxin is a single-chain protein toxin that invades human cells by receptor-mediated endocytosis. In acidic endosomes, its translocation domain inserts into endosomal membranes and facilitates the transport of the catalytic domain (DTA from endosomal lumen into the host cell cytosol. Here, DTA ADP-ribosylates elongation factor 2 inhibits protein synthesis and leads to cell death. The compound 4-bromobenzaldehyde N-(2,6-dimethylphenylsemicarbazone (EGA has been previously shown to protect cells from various bacterial protein toxins which deliver their enzymatic subunits from acidic endosomes to the cytosol, including Bacillus anthracis lethal toxin and the binary clostridial actin ADP-ribosylating toxins C2, iota and Clostridium difficile binary toxin (CDT. Here, we demonstrate that EGA also protects human cells from diphtheria toxin by inhibiting the pH-dependent translocation of DTA across cell membranes. The results suggest that EGA might serve for treatment and/or prevention of the severe disease diphtheria.

  10. Synthesis of Ultra-Small Platinum, Palladium and Gold Nanoparticles by Shewanella loihica PV-4 Electrochemically Active Biofilm and Their Enhanced Catalytic Activities

    KAUST Repository

    Ahmed, Elaf

    2018-02-21

    Ultra-small nanoparticles (USNPs) of noble metals have a great potential in a variety of applications due to their high surface areas and high reactivity. This works employed electrochemically active biofilms (EABs) composed of a single bacterium strain of Shewanella loihica PV-4 and successfully synthesized USNPs of noble metal Au, Pd, and Pt. The synthesized USNPs had a size range between 2 and 7 nm and exhibited excellent catalytic performance in dye decomposition. The results of this work shine lights on the use of EABs in nanoparticle synthesis.

  11. Method and electrochemical cell for synthesis and treatment of metal monolayer electrocatalysts metal, carbon, and oxide nanoparticles ion batch, or in continuous fashion

    Science.gov (United States)

    Adzic, Radoslav; Zhang, Junliang; Sasaki, Kotaro

    2015-04-28

    An apparatus and method for synthesis and treatment of electrocatalyst particles in batch or continuous fashion is provided. In one embodiment, the apparatus comprises a sonication bath and a two-compartment chamber submerged in the sonication bath. The upper and lower compartments are separated by a microporous material surface. The upper compartment comprises a cover and a working electrode (WE) connected to a Pt foil contact, with the foil contact connected to the microporous material. The upper chamber further comprises reference counter electrodes. The lower compartment comprises an electrochemical cell containing a solution of metal ions. In one embodiment, the method for synthesis of electrocatalysts comprises introducing a plurality of particles into the apparatus and applying sonication and an electrical potential to the microporous material connected to the WE. After the non-noble metal ions are deposited onto the particles, the non-noble metal ions are displaced by noble-metal ions by galvanic displacement.

  12. Synthesis and electrochemical properties of Na-rich Prussian blue analogues containing Mn, Fe, Co, and Fe for Na-ion batteries

    Science.gov (United States)

    Bie, Xiaofei; Kubota, Kei; Hosaka, Tomooki; Chihara, Kuniko; Komaba, Shinichi

    2018-02-01

    Electrochemical performance of Prussian blue analogues (PBAs) as positive electrode materials for non-aqueous Na-ion batteries is known to be highly dependent on their synthesis conditions according to the previous researches. Na-rich PBAs, NaxM[Fe(CN)6]·nH2O where M = Mn, Fe, Co, and Ni, are prepared via precipitation method under the same condition. The structure, chemical composition, morphology, valence of the transition metals, and electrochemical property of these samples are comparatively researched. The PBA with Mn shows large reversible capacity of 126 mAh g-1 in 2.0-4.2 V at a current density of 30 mA g-1 and the highest working voltage owning to high redox potential of Mn2+/3+ in MnN6 and Fe2+/3+ in FeC6. While, the PBA with Ni exhibits the best cyclability and rate performance though only 66 mAh g-1 is delivered. The significant differences in electrochemical behaviors of the PBAs originate from the various properties depending on different transition metals.

  13. Electrochemical synthesis of novel polymer based on (4-(2,3-dihydrothieno[3,4-6][1,4][dioxin-5-yl) aniline) in aqueous solution: Characterization and application

    International Nuclear Information System (INIS)

    Shahhosseini, Leyla; Nateghi, Mohammad Reza; Kazemipour, Maryam; Borhani Zarandi, Mahmoud

    2016-01-01

    4-(2,3-dihydrothieno[3,4-6][1,4][dioxin-5-yl) aniline, an interesting novel monomer was successfully synthesized in which α-carbon on ethylenedioxythiophene was linked to aniline at para position. The structure of the monomer was approved by infrared (IR), gas chromatography-mass spectrometry (GC-MS) and "1H nuclear magnetic resonance ("1H NMR) spectroscopies. Poly (4-(2,3-dihydrothieno[3,4-6][1,4][dioxin-5-yl) aniline) and its composite with graphene were electrochemically synthesized in aqueous solution by cyclic potential sweep method. The Polymer was characterized by IR and UV–vis spectroscopies, scanning electron microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy techniques. Electrochemical synthesis conditions were optimized to prepare high conducting and porous polymer so it can be efficiently used as a counter electrode in fabrication of dye sensitized solar cells. Photovoltaic experiments revealed that energy conversion efficiency of the solar cell fabricated using polymer composite (7.52%) is 21% greater than that prepared by Pt counter electrode (6.19%). - Highlights: • A Novel monomer comprising aniline and EDOT was synthesized by a simple process. • Poly (ANI-EDOT) was synthesized and characterized by cyclic potential sweep method. • The copolymer changes from yellow at −0.9 V to dark green color at +0.9 V reversibly. • Poly (ANI-EDOT)/graphene is porous with electrocatalytic effect on I_3"− reduction.

  14. One-pot hydrothermal synthesis, characterization and electrochemical properties of CuS nanoparticles towards supercapacitor applications

    International Nuclear Information System (INIS)

    Krishnamoorthy, Karthikeyan; Rao, Alluri Nagamalleswara; Jae Kim, Sang; Kumar Veerasubramani, Ganesh

    2014-01-01

    In this article, we have investigated the electrochemical properties of CuS nanoparticles for supercapacitor applications. The CuS nanoparticles are prepared by a facile one-pot hydrothermal approach using copper nitrate and thiourea as starting materials. The x-ray diffraction study revealed the formation of covellite CuS. The field-emission scanning electron microscope studies suggested the formation of cubic shaped CuS nanoparticles. The electrochemical studies such as cyclic voltammetry, galvanostatic charge-discharge analysis and electrochemical impedance spectroscopy confirmed the pseudocapacitive nature of the CuS electrodes. The CuS electrode shows a specific capacitance of about 101.34 F g −1 from the cyclic voltammetry at a scan rate of 5 mV s −1 . The electrochemical impedance spectra analyzed using Nyquist plot confirmed the pseudocapacitive behavior of the CuS electrodes. (paper)

  15. Synthesis and Thermophysical Properties of Ether-Functionalized Sulfonium Ionic Liquids as Potential Electrolytes for Electrochemical Applications.

    Science.gov (United States)

    Coadou, Erwan; Goodrich, Peter; Neale, Alex R; Timperman, Laure; Hardacre, Christopher; Jacquemin, Johan; Anouti, Mérièm

    2016-12-05

    During this work, a novel series of hydrophobic room temperature ionic liquids (ILs) based on five ether functionalized sulfonium cations bearing the bis{(trifluoromethyl)sulfonyl}imide, [NTf 2 ] - anion were synthesized and characterized. Their physicochemical properties, such as density, viscosity and ionic conductivity, electrochemical window, along with thermal properties including phase transition behavior and decomposition temperature, have been measured. All of these ILs showed large liquid range temperature, low viscosity, and good conductivity. Additionally, by combining DFT calculations along with electrochemical characterization it appears that these novel ILs show good electrochemical stability windows, suitable for the potential application as electrolyte materials in electrochemical energy storage devices. ©2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  16. Synthesis and electrochemical properties of porous double-shelled Mn2O3 hollow microspheres as a superior anode material for lithium ion batteries

    International Nuclear Information System (INIS)

    Qiao, Yu; Yu, Yan; Jin, Yi; Guan, Yi-Biao; Chen, Chun-Hua

    2014-01-01

    Highlights: • Double-shelled Mn 2 O 3 hollow microspheres are prepared by a multi-step. • synthesis procedure. • Solid, hollow and yolk-structured Mn 2 O 3 spheres are prepared for comparison. • The double-shelled hollow Mn 2 O 3 is superior in electrochemical properties. - Abstract: By means of a specially designed multi-step synthesis procedure involving steps of precipitation, controlled oxidation, selective etching and calcination, porous double-shelled Mn 2 O 3 hollow microspheres are synthesized. Solid, hollow and yolk-structured Mn 2 O 3 are also similarly synthesized for comparison. X-ray diffraction, scanning and transmission electron microscopies, IR spectroscopy, thermogravimetry, and Brunauer-Emmett-Teller measurements are employed to investigate their structures and compositions. Galvanostatic cell cycling and impedance spectroscopy are used to characterize the electrochemical properties of Mn 2 O 3 /Li cells. The results show that the hierarchical hollow structured (double-shelled, hollow and yolk-structured) Mn 2 O 3 anode materials deliver higher reversible capacities and excellent cycling stabilities than the solid Mn 2 O 3 . Moreover, among the three hierarchical hollow structured samples, the double shelled sample possesses the best cycling performance, especially at a high current density

  17. The influence of the synthesis method of Ti/RuO2 electrodes on their stability and catalytic activity for electrochemical oxidation of the pesticide carbaryl

    International Nuclear Information System (INIS)

    Santos, T.É.S.; Silva, R.S.; Carlesi Jara, C.; Eguiluz, K.I.B.; Salazar-Banda, G.R.

    2014-01-01

    In this study, we developed dimensionally stable anodes of titanium covered with ruthenium oxides (Ti/RuO 2 ) using sol–gel, Pechini and ionic liquid (IL) methodologies. The electrochemical efficiency of these electrodes was then evaluated regarding electrochemical degradation of the pesticide carbaryl. The UV–visible spectroscopy measurements showed that the electrodes obtained by the IL and Pechini methods were more effective at pesticide degradation compared with the sol–gel electrode, especially at high current density values. Carbaryl degradation after 2 h of electrolysis at 30 mA cm −2 was 96.4% and 95.5% for the electrodes obtained by the IL and Pechini methods, respectively, while the degradation was 65.0% for the electrodes obtained by the sol–gel method. Additionally, the electrodes prepared by the IL and Pechini methods showed greater physical and electrochemical stability when compared to electrodes obtained by the sol–gel method. Electrodes prepared by the IL method with a few covering layers (three) achieved an elevated and constant area in a more efficient way than electrodes prepared by the Pechini and sol–gel methods. This fact can be attributed to the higher viscosity of the ionic liquid-based precursor solution, which transfers a higher amount of Ru in one single layer, compared to the other methods studied, thus reducing the time for synthesis, the number of calcination steps and the production costs of electrodes. - Highlights: • We developed dimensionally stable anodes containing ruthenium oxides. • Sol–gel, Pechini and ionic liquid methodologies were used. • The ionic liquid method covers the surfaces more efficiently and with few layers. • The proposed method reduces the time and production cost for synthesis of electrodes. • The electrodes synthesized present high stability and pesticide degradation activity

  18. The influence of the synthesis method of Ti/RuO{sub 2} electrodes on their stability and catalytic activity for electrochemical oxidation of the pesticide carbaryl

    Energy Technology Data Exchange (ETDEWEB)

    Santos, T. É.S. [Laboratório de Eletroquímica e Nanotecnologia, Instituto de Tecnologia e Pesquisa (ITP)/Programa de Pós-Graduação em Engenharia de Processos, Universidade Tiradentes, 49032–490 Aracaju, SE (Brazil); Silva, R. S. [Laboratório de Materiais Cerâmicos Avançados, Departamento de Física, Universidade Federal de Sergipe, 49.100-000 São Cristóvão, SE (Brazil); Carlesi Jara, C. [Escuela de Ingeniería Química, Pontificia Universidad Católica de Valparaíso, Av. Brasil No 2147, 2362804 Valparaíso (Chile); Eguiluz, K. I.B. [Laboratório de Eletroquímica e Nanotecnologia, Instituto de Tecnologia e Pesquisa (ITP)/Programa de Pós-Graduação em Engenharia de Processos, Universidade Tiradentes, 49032–490 Aracaju, SE (Brazil); Salazar-Banda, G.R., E-mail: gianrsb@gmail.com [Laboratório de Eletroquímica e Nanotecnologia, Instituto de Tecnologia e Pesquisa (ITP)/Programa de Pós-Graduação em Engenharia de Processos, Universidade Tiradentes, 49032–490 Aracaju, SE (Brazil)

    2014-11-14

    In this study, we developed dimensionally stable anodes of titanium covered with ruthenium oxides (Ti/RuO{sub 2}) using sol–gel, Pechini and ionic liquid (IL) methodologies. The electrochemical efficiency of these electrodes was then evaluated regarding electrochemical degradation of the pesticide carbaryl. The UV–visible spectroscopy measurements showed that the electrodes obtained by the IL and Pechini methods were more effective at pesticide degradation compared with the sol–gel electrode, especially at high current density values. Carbaryl degradation after 2 h of electrolysis at 30 mA cm{sup −2} was 96.4% and 95.5% for the electrodes obtained by the IL and Pechini methods, respectively, while the degradation was 65.0% for the electrodes obtained by the sol–gel method. Additionally, the electrodes prepared by the IL and Pechini methods showed greater physical and electrochemical stability when compared to electrodes obtained by the sol–gel method. Electrodes prepared by the IL method with a few covering layers (three) achieved an elevated and constant area in a more efficient way than electrodes prepared by the Pechini and sol–gel methods. This fact can be attributed to the higher viscosity of the ionic liquid-based precursor solution, which transfers a higher amount of Ru in one single layer, compared to the other methods studied, thus reducing the time for synthesis, the number of calcination steps and the production costs of electrodes. - Highlights: • We developed dimensionally stable anodes containing ruthenium oxides. • Sol–gel, Pechini and ionic liquid methodologies were used. • The ionic liquid method covers the surfaces more efficiently and with few layers. • The proposed method reduces the time and production cost for synthesis of electrodes. • The electrodes synthesized present high stability and pesticide degradation activity.

  19. Electrochemical polymer electrolyte membranes

    CERN Document Server

    Fang, Jianhua; Wilkinson, David P

    2015-01-01

    Electrochemical Polymer Electrolyte Membranes covers PEMs from fundamentals to applications, describing their structure, properties, characterization, synthesis, and use in electrochemical energy storage and solar energy conversion technologies. Featuring chapters authored by leading experts from academia and industry, this authoritative text: Discusses cutting-edge methodologies in PEM material selection and fabricationPoints out important challenges in developing PEMs and recommends mitigation strategies to improve PEM performanceAnalyzes the cur

  20. Novel synthesis of methoxymethyl benzene by electrochemical coupling reaction of toluene with methanol in ionic liquid media.

    Science.gov (United States)

    Chen, Fengtao; Wang, Bo; Ma, Hongzhu

    2009-06-15

    An ionic liquid (1-butyl-3-methylimidazolium dibutyl phosphate) was prepared and characterized by cyclic voltammogram (CV) and Fourier transform infrared spectrometer (FT-IR). The ionic liquid exhibited good catalytic activity for the electrochemical reaction of toluene with methanol assisted with a pair of porous graphite plane electrodes and product yield higher than 56% was observed. In addition, the electrochemical process was detected by UV-vis spectrum and the products were analyzed by gas chromatography/mass spectrometry (GC/MS). According to the experimental results, a possible free radical reaction mechanism was proposed. It may be concluded that a simply and feasible electrochemical coupling reaction at room temperature and atmospheric pressure may be possible. Compared with methyl tert-butyl ether (MTBE), the main product (methoxymethyl benzene) used as booster to improve fuel combustion was also studied.

  1. Synthesis, characterization and electrochemical performance of core/shell structured carbon coated silicon powders for lithium ion battery negative electrodes

    Directory of Open Access Journals (Sweden)

    Tuğrul Çetinkaya

    2017-06-01

    Full Text Available Surface of nano silicon powders were coated with amorphous carbon by pyrolysis of polyacronitrile (PAN polymer. Microstructural characterization of amorphous carbon coated silicon powders (Si-C were carried out using scanning electron microscopy (SEM and thickness of carbon coating is defined by transmission electron microscopy (TEM. Elemental analyses of Si-C powders were performed using energy dispersive X-ray spectroscopy (EDS. Structural and phase characterization of Si-C composite powders were investigated using X-ray diffractometer (XRD and Raman spectroscopy. Produced Si-C powders were prepared as an electrode on the copper current collector and electrochemical tests were carried out using CR2016 button cells at 200 mA/g constant current density. According to electrochemical test results, carbon coating process enhanced the electrochemical performance by reducing the problems stem from volume change and showed 770 mAh/g discharge capacity after 30 cycles.

  2. Synthesis of TiO{sub 2} by electrochemical method from TiCl{sub 4} solution as anode material for lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Nur, Adrian, E-mail: adriannur@staff.uns.ac.id; Purwanto, Agus; Jumari, Arif; Dyartanti, Endah R.; Sari, Sifa Dian Permata; Hanifah, Ita Nur [Research Group of Advanced Material, Department of Chemical Engineering, Sebelas Maret University, Jl. Ir. Sutami 36 A Kentingan, Surakarta Indonesia 57126 (Indonesia)

    2016-02-08

    Metal oxide combined with graphite becomes interesting composition. TiO{sub 2} is a good candidate for Li ion battery anode because of cost, availability of sufficient materials, and environmentally friendly. TiO{sub 2} gravimetric capacity varied within a fairly wide range. TiO{sub 2} crystals form highly depends on the synthesis method used. The electrochemical method is beginning to emerge as a valuable option for preparing TiO{sub 2} powders. Using the electrochemical method, the particle can easily be controlled by simply adjusting the imposed current or potential to the system. In this work, the effects of some key parameters of the electrosynthesis on the formation of TiO{sub 2} have been investigated. The combination of graphite and TiO{sub 2} particle has also been studied for lithium-ion batteries. The homogeneous solution for the electrosynthesis of TiO{sub 2} powders was TiCl{sub 4} in ethanol solution. The electrolysis was carried out in an electrochemical cell consisting of two carbon electrodes with dimensions of (5 × 2) cm. The electrodes were set parallel with a distance of 2.6 cm between the electrodes and immersed in the electrolytic solution at a depth of 2 cm. The electrodes were connected to the positive and negative terminals of a DC power supply. The electrosynthesis was performed galvanostatically at 0.5 to 2.5 hours and voltages were varied from 8 to 12 V under constant stirring at room temperature. The resulted suspension was aged at 48 hrs, filtered, dried directly in an oven at 150°C for 2 hrs, washed 2 times, and dried again 60 °C for 6 hrs. The particle product has been used to lithium-ion battery as anode. Synthesis of TiO{sub 2} particle by electrochemical method at 10 V for 1 to 2.5 hrs resulted anatase and rutile phase.

  3. Synthesis, characterization and electrochemical performances of new antimony-containing graphite compounds used as anodes for lithium-ion batteries

    International Nuclear Information System (INIS)

    Dailly, A.; Willmann, P.; Billaud, D.

    2002-01-01

    Graphite intercalation intercalated with metal alloys able to alloy reversibly lithium constitute a large set of new anodic materials for lithium-ion batteries of significantly improved reversible capacities. Especially, graphite intercalated with cesium-antimony alloys can be used as materials for anodes in lithium-ion batteries. Electrochemical insertion of lithium in such chemically modified precursors shows that lithium both intercalates in the empty van der Waals spaces of graphite and alloys reversibly with antimony. The total electrochemical reversible capacities, measured between 0 and 2 V vs Li + /Li, close to 700 mAh g -1 have been currently obtained

  4. Synthesis and electrochemical characterization of hybrid membrane Nafion-SiO2 for application as polymer electrolyte in PEM fuel cell

    International Nuclear Information System (INIS)

    Dresch, Mauro Andre

    2009-01-01

    In this work, the effect of sol-gel synthesis parameters on the preparation and polarization response of Nafion-SiO 2 hybrids as electrolytes for proton exchange membrane fuel cells (PEMFC) operating at high temperatures (130 degree C) was evaluated. The inorganic phase was incorporated in a Nafion matrix with the following purposes: to improve the Nafion water uptake at high temperatures (> 100 degree C); to increase the mechanical strength of Nafion and; to accelerate the electrode reactions. The hybrids were prepared by an in-situ incorporation of silica into commercial Nafion membranes using an acid-catalyzed sol-gel route. The effects of synthesis parameters, such as catalyst concentration, sol-gel solvent, temperature and time of both hydrolysis and condensation reactions, and silicon precursor concentration (Tetraethyl orthosilicate - TEOS), were evaluated as a function on the incorporation degree and polarization response. Nafion-SiO 2 hybrids were characterized by gravimetry, thermogravimetric analysis (TGA), scanning electron microscopy and X-ray dispersive energy (SEM-EDS), electrochemical impedance spectroscopy (EIS), and X-ray small angle scattering (SAXS). The hybrids were tested as electrolyte in single H 2 /O 2 fuel cells in the temperature range of 80 - 130 degree C and at 130 degree C and reduced relative humidity (75% and 50%). Summarily, the hybrid performance showed to be strongly dependent on the synthesis parameters, mainly, the type of alcohol and the TEOS concentration. (author)

  5. High power Nb-doped LiFePO4 Li-ion battery cathodes; pilot-scale synthesis and electrochemical properties

    Science.gov (United States)

    Johnson, Ian D.; Blagovidova, Ekaterina; Dingwall, Paul A.; Brett, Dan J. L.; Shearing, Paul R.; Darr, Jawwad A.

    2016-09-01

    High power, phase-pure Nb-doped LiFePO4 (LFP) nanoparticles are synthesised using a pilot-scale continuous hydrothermal flow synthesis process (production rate of 6 kg per day) in the range 0.01-2.00 at% Nb with respect to total transition metal content. EDS analysis suggests that Nb is homogeneously distributed throughout the structure. The addition of fructose as a reagent in the hydrothermal flow process, followed by a post synthesis heat-treatment, affords a continuous graphitic carbon coating on the particle surfaces. Electrochemical testing reveals that cycling performance improves with increasing dopant concentration, up to a maximum of 1.0 at% Nb, for which point a specific capacity of 110 mAh g-1 is obtained at 10 C (6 min for the charge or discharge). This is an excellent result for a high power cathode LFP based material, particularly when considering the synthesis was performed on a large pilot-scale apparatus.

  6. Facile synthesis of Co3O4 nanowires grown on hollow NiO microspheres with superior electrochemical performance

    International Nuclear Information System (INIS)

    Fan, Meiqing; Ren, Bo; Yu, Lei; Song, Dalei; Liu, Qi; Liu, Jingyuan; Wang, Jun; Jing, Xiaoyan; Liu, Lianhe

    2015-01-01

    Graphical abstract: Display Omitted - Highlights: • The NiO hollow spheres were decorated by Co 3 O 4 nanowires. • The NiO hollow spheres were comprised of many NiO particles. • The Co 3 O 4 nanowires were composed of nanoparticles. • The NiO/Co 3 O 4 core/shell nanocomposites have good electrochemical properties. - Abstract: The NiO/Co 3 O 4 core/shell composites as a promising supercapacitor material have been fabricated by facile hydrothermal process. The structure and morphology of the NiO/Co 3 O 4 core/shell composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results indicated that the NiO hollow spheres were decorated by Co 3 O 4 nanowires, and the nanowires were composed of nanoparticles. Electrochemical properties were characterized by cyclic voltammetry, galvanostatic charge/discharge measurements, and electrochemical impedance spectroscopy. The results suggested that the NiO/Co 3 O 4 core/shell composites had good electrochemical reversibility and displayed superior capacitive performance with large capacitance (510 F g −1 ). Moreover, NiO/Co 3 O 4 core/shell composites showed excellent cyclic performanceafter 1000 cycles

  7. Electrochemical Synthesis of Polypyrrole, Reduced Graphene Oxide, and Gold Nanoparticles Composite and Its Application to Hydrogen Peroxide Biosensor

    Directory of Open Access Journals (Sweden)

    Baoyan Wu

    2016-11-01

    Full Text Available Here we report a facile eco-friendly one-step electrochemical approach for the fabrication of a polypyrrole (PPy, reduced graphene oxide (RGO, and gold nanoparticles (nanoAu biocomposite on a glassy carbon electrode (GCE. The electrochemical behaviors of PPy–RGO–nanoAu and its application to electrochemical detection of hydrogen peroxide were investigated by cyclic voltammetry. Graphene oxide and pyrrole monomer were first mixed and casted on the surface of a cleaned GCE. After an electrochemical processing consisting of the electrooxidation of pyrrole monomer and simultaneous electroreduction of graphene oxide and auric ions (Au3+ in aqueous solution, a PPy–RGO–nanoAu biocomposite was synthesized on GCE. Each component of PPy–RGO–nanoAu is electroactive without non-electroactive substance. The obtained PPy–RGO–nanoAu/GCE exhibited high electrocatalytic activity toward hydrogen peroxide, which allows the detection of hydrogen peroxide at a negative potential of about −0.62 V vs. SCE. The amperometric responses of the biosensor displayed a sensitivity of 40 µA/mM, a linear range of 32 µM–2 mM, and a detection limit of 2.7 µM (signal-to-noise ratio = 3 with good stability and acceptable reproducibility and selectivity. The results clearly demonstrate the potential of the as-prepared PPy–RGO–nanoAu biocomposite for use as a highly electroactive matrix for an amperometric biosensor.

  8. Synthesis and Electrochemical Properties of Fe-doped V6O13 as Cathode Material for Lithium-ion Battery

    Directory of Open Access Journals (Sweden)

    YUAN Qi

    2018-01-01

    Full Text Available Fe-doped V6O13 was synthesized via a facile hydrothermal method after preparing precursor in order to improve the discharge capacity and cycle performance of V6O13 cathode material at high-lithium state. XRD, SEM and XPS were employed to characterize the phase, morphology and valence of the Fe-doped V6O13. Meanwhile, the electrochemical performance was analyzed and researched. Different morphologies and electrochemical performances of Fe-doped V6O13 were obtained via doping different contents of Fe3+ ion. The sample 0.02 presented the largest thickness of nanosheets (the thickness of 600-900nm and clearance between layers. The Fe-doped V6O13 has a better electrochemical performance than that of pure V6O13. The sample 0.02 exhibits the best electrochemical performance, the initial discharge specific capacity is 433mAh·g-1 and the capacity retention is 47.1% after 100 cycles.

  9. Synthesis of palladium nanoparticle modified reduced graphene oxide and multi-walled carbon nanotube hybrid structures for electrochemical applications

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Jie, E-mail: hujie@tyut.edu.cn [Micro and Nano System Research Center, Key Lab of Advanced Transducers and Intelligent Control System (Ministry of Education) & College of Information Engineering, Taiyuan University of Technology, Taiyuan, 030024, Shanxi (China); Zhao, Zhenting; Zhang, Jun; Li, Gang; Li, Pengwei; Zhang, Wendong [Micro and Nano System Research Center, Key Lab of Advanced Transducers and Intelligent Control System (Ministry of Education) & College of Information Engineering, Taiyuan University of Technology, Taiyuan, 030024, Shanxi (China); Lian, Kun, E-mail: liankun@tyut.edu.cn [Micro and Nano System Research Center, Key Lab of Advanced Transducers and Intelligent Control System (Ministry of Education) & College of Information Engineering, Taiyuan University of Technology, Taiyuan, 030024, Shanxi (China); School of Nano-Science and Nano-Engineering, Suzhou & Collaborative Innovation Center of Suzhou Nano Science and Technology, Xi' an Jiaotong University, Xi' an, 710049 (China); Center for Advanced Microstructures and Devices, Louisiana State University, LA, 70806 (United States)

    2017-02-28

    Graphical abstract: A sensitive hydrazine electrochemical sensor was fabricated by using palladium (Pd) nanoparticle functionalized reduced graphene oxide (rGO) and multi-walled carbon nanotube (MWCNTs) hybrid structures (Pd/rGO-MWCNTs). - Highlights: • rGO-MWCNTs hybrid structures and Pd nanoparticles are prepared using electrochemical methods. • rGO-MWCNTs hybrid films are used as supports and co-catalysts for Pd nanoparticles. • The Pd/rGO-MWCNTs hybrid structure based sensor shows an ultra-high sensitivity of 7.09 μA μM{sup −1} cm{sup −2} and a low detection limit of 0.15 μM. • The proposed electrochemical sensor exhibits excellent selectivity. - Abstract: In this work, palladium (Pd) nanoparticles functionalized reduced graphene oxide (rGO) and multi-walled carbon nanotubes (MWCNTs) hybrid structures (Pd/rGO-MWCNTs) were successfully prepared by a combination of electrochemical reduction with electrodeposition method. The morphology, structure, and composition of the Pd/rGO-MWCNTs hybrid were characterized by scanning electron microscopy, transmission electron microscopy and energy dispersive spectroscopy. The as-synthesized hybrid structures were modified on the glassy carbon electrode (GCE) and further utilized for hydrazine sensing. Electrochemical impedance spectroscopic, cyclic voltammetry and single-potential amperometry experiments were carried out on Pd/rGO-MWCNTs hybrid structures to investigate the interface properties and sensing performance. The measured results demonstrate that the fabricated Pd/rGO-MWCNTs/GCE sensor show a high sensitivity of 7.09 μA μM{sup −1} cm{sup −2} in a large concentration range of 1.0 to 1100 μM and a low detection limit of 0.15 μM. Moreover, the as-prepared sensor exhibits good selectivity and stability for the determination of hydrazine under interference conditions.

  10. Synthesis of palladium nanoparticle modified reduced graphene oxide and multi-walled carbon nanotube hybrid structures for electrochemical applications

    International Nuclear Information System (INIS)

    Hu, Jie; Zhao, Zhenting; Zhang, Jun; Li, Gang; Li, Pengwei; Zhang, Wendong; Lian, Kun

    2017-01-01

    Graphical abstract: A sensitive hydrazine electrochemical sensor was fabricated by using palladium (Pd) nanoparticle functionalized reduced graphene oxide (rGO) and multi-walled carbon nanotube (MWCNTs) hybrid structures (Pd/rGO-MWCNTs). - Highlights: • rGO-MWCNTs hybrid structures and Pd nanoparticles are prepared using electrochemical methods. • rGO-MWCNTs hybrid films are used as supports and co-catalysts for Pd nanoparticles. • The Pd/rGO-MWCNTs hybrid structure based sensor shows an ultra-high sensitivity of 7.09 μA μM"−"1 cm"−"2 and a low detection limit of 0.15 μM. • The proposed electrochemical sensor exhibits excellent selectivity. - Abstract: In this work, palladium (Pd) nanoparticles functionalized reduced graphene oxide (rGO) and multi-walled carbon nanotubes (MWCNTs) hybrid structures (Pd/rGO-MWCNTs) were successfully prepared by a combination of electrochemical reduction with electrodeposition method. The morphology, structure, and composition of the Pd/rGO-MWCNTs hybrid were characterized by scanning electron microscopy, transmission electron microscopy and energy dispersive spectroscopy. The as-synthesized hybrid structures were modified on the glassy carbon electrode (GCE) and further utilized for hydrazine sensing. Electrochemical impedance spectroscopic, cyclic voltammetry and single-potential amperometry experiments were carried out on Pd/rGO-MWCNTs hybrid structures to investigate the interface properties and sensing performance. The measured results demonstrate that the fabricated Pd/rGO-MWCNTs/GCE sensor show a high sensitivity of 7.09 μA μM"−"1 cm"−"2 in a large concentration range of 1.0 to 1100 μM and a low detection limit of 0.15 μM. Moreover, the as-prepared sensor exhibits good selectivity and stability for the determination of hydrazine under interference conditions.

  11. Electrochemical synthesis of novel polymer based on (4-(2,3-dihydrothieno[3,4-6][1,4][dioxin-5-yl) aniline) in aqueous solution: Characterization and application

    Energy Technology Data Exchange (ETDEWEB)

    Shahhosseini, Leyla [Chemistry Department, Kerman Branch, Islamic Azad University, Kerman (Iran, Islamic Republic of); Nateghi, Mohammad Reza, E-mail: mnateghi@iauyazd.ac.ir [Chemistry Department, Yazd Branch, Islamic Azad University, Yazd (Iran, Islamic Republic of); Kazemipour, Maryam [Chemistry Department, Kerman Branch, Islamic Azad University, Kerman (Iran, Islamic Republic of); Borhani Zarandi, Mahmoud [Department of Physics, Yazd University, P.O. Box 97175/615, Yazd (Iran, Islamic Republic of)

    2016-07-01

    4-(2,3-dihydrothieno[3,4-6][1,4][dioxin-5-yl) aniline, an interesting novel monomer was successfully synthesized in which α-carbon on ethylenedioxythiophene was linked to aniline at para position. The structure of the monomer was approved by infrared (IR), gas chromatography-mass spectrometry (GC-MS) and {sup 1}H nuclear magnetic resonance ({sup 1}H NMR) spectroscopies. Poly (4-(2,3-dihydrothieno[3,4-6][1,4][dioxin-5-yl) aniline) and its composite with graphene were electrochemically synthesized in aqueous solution by cyclic potential sweep method. The Polymer was characterized by IR and UV–vis spectroscopies, scanning electron microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy techniques. Electrochemical synthesis conditions were optimized to prepare high conducting and porous polymer so it can be efficiently used as a counter electrode in fabrication of dye sensitized solar cells. Photovoltaic experiments revealed that energy conversion efficiency of the solar cell fabricated using polymer composite (7.52%) is 21% greater than that prepared by Pt counter electrode (6.19%). - Highlights: • A Novel monomer comprising aniline and EDOT was synthesized by a simple process. • Poly (ANI-EDOT) was synthesized and characterized by cyclic potential sweep method. • The copolymer changes from yellow at −0.9 V to dark green color at +0.9 V reversibly. • Poly (ANI-EDOT)/graphene is porous with electrocatalytic effect on I{sub 3}{sup −} reduction.

  12. Electrochemical Synthesis, Structure Elucidation and Antibacterial Evaluation of 9a-aza-9a-chloro-9a-homoerythromycin A

    Directory of Open Access Journals (Sweden)

    Zoran Mandic

    2014-09-01

    Full Text Available Electrochemical synthesis, structure elucidation and antibacterial evaluation of 9a-aza-9a-chloro-9a-homoerythromycin A were carried out. It was found that the anodic oxidation of 9a-aza-9a-homoerythromycin A via electrogenerated reactive chlorine species leads to the chlorination of lactam nitrogen in high yield provided the pH of the reaction mixture is maintained above 3. NOESY spectra reveal the existence of the mixture of two conformational families in the solution, the "folding-out" conformer being slightly more abundant comparing to 9a-Aza-9a-homoerythromycin A. The chlorine substitution of lactam hydrogen resulted in improved antimicrobial potency against Sreptococcus pyogenes PSCB0542, Moraxella catarrhalis ATCC 25238, Haemophilus  influenzae ATCC 49247 and Enteroccocus faecalis ATCC 29212.

  13. MOF-derived Cu-Pd/nanoporous carbon composite as an efficient catalyst for hydrogen evolution reaction: A comparison between hydrothermal and electrochemical synthesis

    Science.gov (United States)

    Mandegarzad, Sakineh; Raoof, Jahan Bakhsh; Hosseini, Sayed Reza; Ojani, Reza

    2018-04-01

    In this study, a novel catalyst based on Cu-Pd bimetallic nanoparticles supported on nanoporous carbon composite (NPCC) is successfully fabricated through three-step process and used as an electrocatalyst towards hydrogen evolution reaction (HER). At the first step, MOF-199 is synthesized via two distinct strategies; (1) hydrothermal (HT) and (2) electrochemical (EC). Next, the synthesized MOF-199 is used as a template in order to prepare Cu/NPCC by direct carbonization under N2 atmosphere followed by galvanic replacement reaction of Cu metals by PdII ions. All the prepared materials are characterized by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), and nitrogen adsorption/desorption measurements. The effect of synthesis method of MOF-199 on the electrocatalytic activity of the final product towards HER is investigated. The electrochemical measurements indicate that Cu-Pd/NPCC derived from the MOF prepared by EC method (Cu-Pd/NPCC/EC) exhibits an enhanced catalytic activity towards HER in H2SO4 solution than the Cu-Pd/NPCC/HT. This improvement may be attributed to using of supporting electrolyte in the preparation of Cu-Pd/NPCC/EC.

  14. High surface area synthesis, electrochemical activity, and stability of tungsten carbide supported Pt during oxygen reduction in proton exchange membrane fuel cells

    Science.gov (United States)

    Chhina, H.; Campbell, S.; Kesler, O.

    The oxidation of carbon catalyst supports to carbon dioxide gas leads to degradation in catalyst performance over time in proton exchange membrane fuel cells (PEMFCs). The electrochemical stability of Pt supported on tungsten carbide has been evaluated on a carbon-based gas diffusion layer (GDL) at 80 °C and compared to that of HiSpec 4000™ Pt/Vulcan XC-72R in 0.5 M H 2SO 4. Due to other electrochemical processes occurring on the GDL, detailed studies were also performed on a gold mesh substrate. The oxygen reduction reaction (ORR) activity was measured both before and after accelerated oxidation cycles between +0.6 V and +1.8 V vs. RHE. Tafel plots show that the ORR activity remained high even after accelerated oxidation tests for Pt/tungsten carbide, while the ORR activity was extremely poor after accelerated oxidation tests for HiSpec 4000™. In order to make high surface area tungsten carbide, three synthesis routes were investigated. Magnetron sputtering of tungsten on carbon was found to be the most promising route, but needs further optimization.

  15. High surface area synthesis, electrochemical activity, and stability of tungsten carbide supported Pt during oxygen reduction in proton exchange membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Chhina, H. [Automotive fuel cell corporation, 9000 Glenlyon Parkway, Burnaby, BC (Canada); Department of Mechanical and Industrial Engineering, 5 King' s College Road, University of Toronto, Toronto, Ontario (Canada); Campbell, S. [Automotive fuel cell corporation, 9000 Glenlyon Parkway, Burnaby, BC (Canada); Kesler, O. [Department of Mechanical and Industrial Engineering, 5 King' s College Road, University of Toronto, Toronto, Ontario (Canada)

    2008-04-15

    The oxidation of carbon catalyst supports to carbon dioxide gas leads to degradation in catalyst performance over time in proton exchange membrane fuel cells (PEMFCs). The electrochemical stability of Pt supported on tungsten carbide has been evaluated on a carbon-based gas diffusion layer (GDL) at 80 C and compared to that of HiSpec 4000 trademark Pt/Vulcan XC-72R in 0.5 M H{sub 2}SO{sub 4}. Due to other electrochemical processes occurring on the GDL, detailed studies were also performed on a gold mesh substrate. The oxygen reduction reaction (ORR) activity was measured both before and after accelerated oxidation cycles between +0.6 V and +1.8 V vs. RHE. Tafel plots show that the ORR activity remained high even after accelerated oxidation tests for Pt/tungsten carbide, while the ORR activity was extremely poor after accelerated oxidation tests for HiSpec 4000 trademark. In order to make high surface area tungsten carbide, three synthesis routes were investigated. Magnetron sputtering of tungsten on carbon was found to be the most promising route, but needs further optimization. (author)

  16. Synthesis of LiFePO4/Graphene Nano composite and Its Electrochemical Properties as Cathode Material for Li-Ion Batteries

    International Nuclear Information System (INIS)

    Ma, X.; Chen, G.; Liu, Q.; Zeng, G.; Wu, T.

    2014-01-01

    LiFePO 4 /graphene nano composite was successfully synthesized by rheological phase method and its electrochemical properties as the cathode materials for lithium ion batteries were measured. As the iron source in the synthesis, FeOOH nano rods anchored on graphene were first synthesized. The FeOOH nano rods precursors and the final LiFePO 4 /graphene nano composite products were characterized by XRD, SEM, and TEM. While the FeOOH precursors were nano rods with 5-10 nm in diameter and 10-50 nm in length, the LiFePO 4 were nanoparticles with 20-100 nm in size. Compared with the electrochemical properties of LiFePO 4 particles without graphene nano sheets, it is clear that the graphene nano sheets can improve the performances of LiFePO 4 as the cathode material for lithium ion batteries. The as-synthesized LiFePO 4 /graphene nano composite showed high capacities and good cyclabilities. When measured at room temperature and at the rate of 0.1 C (1 C = 170 mA g -1 ), the composite showed a discharge capacity of 156 mA h g -1 in the first cycle and a capacity retention of 96% after 15 cycles. The improved performances of the composite are believed to be the result of the three-dimensional conducting network formed by the flexible and planar graphene nano sheets.

  17. Synthesis and electrochemical characterization of mesoporous Li2FeSiO4/C composite cathode material for Li-ion batteries

    Science.gov (United States)

    Kumar, Ajay; Jayakumar, O. D.; Bazzi, Khadije; Nazri, Gholam-Abbas; Naik, Vaman M.; Naik, Ratna

    2015-03-01

    Lithium iron silicate (Li2FeSiO4) has the potential as cathode for Li ion batteries due to its high theoretical capacity (~ 330 mAh/g) and improved safety. The application of Li2FeSiO4 as cathode material has been challenged by its poor electronic conductivity and slow lithium ion diffusion in the solid phase. In order to solve these problems, we have synthesized mesoporous Li2FeSiO4/C composites by sol-gel method using the tri-block copolymer (P123) as carbon source. The phase purity and morphology of the composite materials were characterized by x-ray diffraction, SEM and TEM. The XRD pattern confirmed the formation of ~ 12 nm size Li2FeSiO4 crystallites in composites annealed at 600 °C for 6 h under argon atmosphere. The electrochemical properties are measured using the composite material as positive electrode in a standard coin cell configuration with lithium as the active anode and the cells were tested using AC impedance spectroscopy, cyclic voltammetry, and galvanostatic charge/discharge cycling. The Li2FeSiO4/C composites showed a discharge capacity of ~ 240 mAh/g at a rate of C/30 at room temperature. The effect of different annealing temperature and synthesis time on the electrochemical performance of Li2FeSiO4/C will be presented.

  18. One-step and low-temperature synthesis of iodine-doped graphene and its multifunctional applications for hydrogen evolution reaction and electrochemical sensing

    International Nuclear Information System (INIS)

    Chu, Ke; Wang, Fan; Zhao, Xiao-lin; Wei, Xiao-ping; Wang, Xin-wei; Tian, Ye

    2017-01-01

    Iodine (I) has emerged as a powerful heteroatom dopant for efficiently tailoring the electrocatalytic properties of graphene. However, the preparation methods of I-doped graphene (I-G) and its electrocatalysis applications remain largely unexplored. Herein, a one-step and low-temperature hydrothermal approach was developed for the successful synthesis of I-G with a high I-doping level (0.52 at.%). The resulting I-G was then applied as a metal-free catalyst for hydrogen evolution reaction (HER) and electrochemical sensing. It was shown that the I-G exhibited a dramatically enhanced HER activity compared to undoped graphene, attributed to the critical role of I-doping in offering large exposed active sites and high electron transfer capability. Furthermore, I-G also displayed attractive sensing performances for highly sensitive and selective detection of dopamine. These findings demonstrate that the hydrothermally synthesized I-G can be a promising electrocatalyst for multifunctional applications in water-splitting and electrochemical sensing.

  19. Use of Dendrimers during the Synthesis of Pt-Ru Electrocatalysts for PEM Fuel Cells: Effects on the Physical and Electrochemical Properties

    Directory of Open Access Journals (Sweden)

    J. C. Calderón

    2011-01-01

    Full Text Available In this work, Pt-Ru catalysts were synthesized by a novel methodology which includes the use as encapsulating molecules of dendrimers of different generation: zero (DN-0, one (DN-1, two (DN-2, and three (DN-3. Synthesized catalysts were heat-treated at 350°C, and the effects of this treatment was established from the physical (X-ray dispersive energy (XDE and X-ray diffraction (XRD and electrochemical characterization (cyclic voltammetry and chronoamperometry. Results showed that the heat-treatment benefits the catalytic properties of synthesized materials in terms of CO and methanol electrochemical oxidation. The curves for CO stripping were more defined for heat-treated catalysts, and methanol oxidation current densities were higher for these materials. These changes are principally explained from the removal of organic residues remaining on the surface of the Pt-Ru nanoparticles after the synthesis procedure. After the activation of the catalysts by heating at 350°C, the real importance of the use of these encapsulating molecules and the effect of the generation of the dendrimer become visible. From these results, it can be concluded that synthesized catalysts are good catalytic anodes for direct methanol fuel cells (DMFCs.

  20. Synthesis of LiFePO4/Graphene Nanocomposite and Its Electrochemical Properties as Cathode Material for Li-Ion Batteries

    Directory of Open Access Journals (Sweden)

    Xiaoling Ma

    2015-01-01

    Full Text Available LiFePO4/graphene nanocomposite was successfully synthesized by rheological phase method and its electrochemical properties as the cathode materials for lithium ion batteries were measured. As the iron source in the synthesis, FeOOH nanorods anchored on graphene were first synthesized. The FeOOH nanorods precursors and the final LiFePO4/graphene nanocomposite products were characterized by XRD, SEM, and TEM. While the FeOOH precursors were nanorods with 5–10 nm in diameter and 10–50 nm in length, the LiFePO4 were nanoparticles with 20–100 nm in size. Compared with the electrochemical properties of LiFePO4 particles without graphene nanosheets, it is clear that the graphene nanosheets can improve the performances of LiFePO4 as the cathode material for lithium ion batteries. The as-synthesized LiFePO4/graphene nanocomposite showed high capacities and good cyclabilities. When measured at room temperature and at the rate of 0.1C (1C = 170 mA g−1, the composite showed a discharge capacity of 156 mA h g−1 in the first cycle and a capacity retention of 96% after 15 cycles. The improved performances of the composite are believed to be the result of the three-dimensional conducting network formed by the flexible and planar graphene nanosheets.

  1. Synthesis and electrochemical properties of nanosized LiFeO2 particles with a layered rocksalt structure for lithium batteries

    International Nuclear Information System (INIS)

    Hirayama, Masaaki; Tomita, Hiroki; Kubota, Kei; Ido, Hidekazu; Kanno, Ryoji

    2012-01-01

    Highlights: ► 40-nm-sized O3-LiFeO 2 exhibits higher discharge capacities and rate characteristics than 400-nm-sized O3-LiFeO 2 . ► The cation disorder of Li and Fe ions might have affected the electrochemical activity of the O3-LiFeO 2 nanoparticles. ► A phase change from a layered structure to a cubic structure during electrochemical cycling. ► The new cubic phase allowed a stable electrochemical reaction between 4.5 and 1.0 V. -- Abstract: Layered rocksalt-type LiFeO 2 particles (O3-LiFeO 2 ) with average particle sizes of ca. 40 and 400 nm were synthesized by an ion exchange reaction from α-NaFeO 2 precursors. X-ray diffraction (XRD) patterns and scanning electron microscopy (SEM) images confirmed the formation of nanosized O3-LiFeO 2 . 40-nm LiFeO 2 exhibited a higher discharge capacity (115 mAh g −1 ) than 400-nm LiFeO 2 (80 mAh g −1 ), and also had better rate characteristics. The downsizing effect and cation disorder between the lithium and iron layers may have improved the electrochemical activity of the LiFeO 2 particles. Transmission electron microscopy (TEM) observation indicated a phase transition from O3-LiFeO 2 to a cubic lattice system during the electrochemical process. The cubic lithium iron oxide exhibited stable electrochemical reactions based on the Fe 2+ /Fe 3+ and Fe 2+ /Fe 0 redox couples at voltages between 4.5 and 1.0 V. The discharge capacities of 40-nm LiFeO 2 were ca. 115, 210, and 390 mAh g −1 under cutoff voltages of 4.5–2.0 V, 4.5–1.5 V, and 4.5–1.0 V, respectively.

  2. Synthesis of new copper nanoparticle-decorated anchored type ligands: Applications as non-enzymatic electrochemical sensors for hydrogen peroxide

    Energy Technology Data Exchange (ETDEWEB)

    Ensafi, Ali A., E-mail: Ensafi@cc.iut.ac.ir; Zandi-Atashbar, N.; Ghiaci, M.; Taghizadeh, M.; Rezaei, B.

    2015-02-01

    In this work, copper nanoparticles (CuNPs) decorated on two new anchored type ligands were utilized to prepare two electrochemical sensors. These ligands are made from bonding amine chains to silica support including SiO{sub 2}–pro–NH{sub 2} (compound I) and SiO{sub 2}–pro–NH–cyanuric–NH{sub 2} (compound II). The morphology of synthesized CuNPs was characterized by transmission electron microscopy (TEM). The nano-particles were in the range of 13–37 nm with the average size of 23 nm. These materials were used to modify carbon paste electrode. Different electrochemical techniques, including cyclic voltammetry, electrochemical impedance spectroscopy and hydrodynamic chronoamperometry, were used to study the sensor behavior. These electrochemical sensors were used as a model for non-enzymatic detection of hydrogen peroxide (H{sub 2}O{sub 2}). To evaluate the abilities of the modified electrodes for H{sub 2}O{sub 2} detection, the electrochemical signals were compared in the absence and presence of H{sub 2}O{sub 2}. From them, two modified electrodes showed significant responses vs. H{sub 2}O{sub 2} addition. The amperograms illustrated that the sensors were selective for H{sub 2}O{sub 2} sensing with linear ranges of 5.14–1250 μmol L{sup −1} and 1.14–1120 μmol L{sup −1} with detection limits of 0.85 and 0.27 μmol L{sup −1} H{sub 2}O{sub 2}, sensitivities of 3545 and 11,293 μA mmol{sup −1} L and with response times less than 5 s for I/CPE and II/CPE, respectively. As further verification of the selected sensor, H{sub 2}O{sub 2} contained in milk sample was analyzed and the obtained results were comparable with the ones from classical control titration method. - Highlights: • Copper nanoparticles decorating on two new anchored type ligands were prepared. • Ligands are bonding to silica support as SiO{sub 2}–pro–NH{sub 2} and SiO{sub 2}–pro–NH–cyanuric–NH{sub 2}. • These materials were used as electrochemical sensors for H

  3. Synthesis and electrochemical properties of a new benzimidazole derivative as the acceptor unit in donor–acceptor–donor type polymers

    International Nuclear Information System (INIS)

    Ozelcaglayan, Ali Can; Sendur, Merve; Akbasoglu, Naime; Apaydin, Dogukan Hazar; Cirpan, Ali; Toppare, Levent

    2012-01-01

    A new benzimidazole unit, 4′-(tert-butyl)spiro[benzo[d]imidazole-2,1′-cyclohexane] was synthesized and coupled with different donor units like 3-hexylthiophene and 3,4-ethylenedioxythiophene (EDOT) via Stille coupling. The donor–acceptor–donor (D–A–D) type monomers, 4′-(tert-butyl)-4,7-bis(4-hexylthiophen-2-yl) spiro[benzo[d]imidazole-2,1′-cyclohexane] (BIHT) and 4′-(tert-butyl)-4,7-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl) spiro[benzo[d]imidazole-2,1′-cyclohexane] (BIED) were electrochemically polymerized, their electrochemical and optical properties were investigated by cyclic voltammetry, UV–vis-NIR spectroscopy techniques. Effect of donor groups on the optical and electronic properties of polymer was studied.

  4. Hydrothermal synthesis of reduced graphene sheets/Fe2O3 nanorods composites and their enhanced electrochemical performance for supercapacitors

    Science.gov (United States)

    Yang, Wanlu; Gao, Zan; Wang, Jun; Wang, Bin; Liu, Lianhe

    2013-06-01

    Reduced graphene nanosheets/Fe2O3 nanorods (GNS/Fe2O3) composite has been fabricated by a hydrothermal route for supercapacitor electrode materials. The obtained GNS/Fe2O3 composite formed a uniform structure with the Fe2O3 nanorods grew on the graphene surface and/or filled between the graphene sheets. The electrochemical performances of the GNS/Fe2O3 hybrid supercapacitor were tested by cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge-discharge tests in 6 M KOH electrolyte. Comparing with the pure Fe2O3 electrode, GNS/Fe2O3 composite electrode exhibits an enhanced specific capacitance of 320 F g-1 at 10 mA cm-2 and an excellent cycle-ability with capacity retention of about 97% after 500 cycles. The simple and cost-effective preparation technique of this composite with good capacitive behavior encourages its potential commercial application.

  5. Synthesis of multilayered structure of nano-dimensional silica glass/reduced graphene oxide for advanced electrochemical applications.

    Science.gov (United States)

    Ghosh, Arnab; Miah, Milon; Majumder, Chinmoy; Bag, Shekhar; Chakravorty, Dipankar; Saha, Shyamal Kumar

    2018-03-28

    During the past few years, intensive research has been carried out to design new functional materials for superior electrochemical applications. Due to low storage capacity and low charge transport, silica based glasses have not yet been investigated for their supercapacitive behavior. Therefore, in the present study, a multilayered structure of silica-based nanoglass and reduced graphene oxide has been designed to remarkably enhance the specific capacitance by exploiting the porosity, large surface area, sufficient dangling bonds in the nanoglass and high electrical conductivity of rGO. The charge transport in the composite structure is also investigated to understand the electrochemical properties. It is found that Simmons tunneling or direct tunneling is the dominant mechanism of charge conduction between the graphene layers via the potential barrier of silica nanoglass phase. We believe that this study will open up a new area in the design of glass-based two-dimensional nanocomposites for superior supercapacitor applications.

  6. Electrochemical oxidation of 3,5-di-tert-butylcatechol: Synthesis and characterization of the formed ortho-benzoquinhydrone derivative

    International Nuclear Information System (INIS)

    Nematollahi, D.; Shayani-Jam, H.

    2006-01-01

    Electrochemical oxidation of 3,5-di-tert-butylcatechol (1) has been studied in ethanol/water mixtures by means of cyclic voltammetry and controlled-potential coulometry. The results revealed that 3,5-di-tert-butyl-1,2-benenzoquinone (2) derived from oxidation of 3,5-di-tert-butylcatechol participate in noncovalently linked interactions with 1 converted to an ortho-benzoquinhydrone (3). The structure of 3 was characterized by MS, IR, 1 H NMR and 13 C NMR. The 1 H NMR studies reveal that the benzoquinhydrone complex 3 is stabilized by one H-bonding interaction. In this work we derived a novel ortho-bezoquinhydrone type complex (3) based on electrochemical oxidation of 3,5-di-tert-butylcatechol at carbon electrode in an undivided cell

  7. One step electrochemical synthesis of bimetallic PdAu supported on nafion–graphene ribbon film for ethanol electrooxidation

    Energy Technology Data Exchange (ETDEWEB)

    Shendage, Suresh S., E-mail: sureshsshendage@gmail.com; Singh, Abilash S.; Nagarkar, Jayashree M., E-mail: jm.nagarkar@ictmumbai.edu.in

    2015-10-15

    Highlights: • Electrochemical deposition of bimetallic PdAu NPs. • Highly loaded PdAu NPs are obtained. • Nafion–graphene supported PdAu NPs shows good activity for ethanol electrooxidation. - Abstract: A nafion–graphene ribbon (Nf–GR) supported bimetallic PdAu nanoparticles (PdAu/Nf–GR) catalyst was prepared by electrochemical codeposition of Pd and Au at constant potential. The prepared catalyst was characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), transmission electron microscopy (TEM) and X-ray diffraction analysis (XRD). The average particle size of PdAu nanoparticles (NPs) determined from XRD was 3.5 nm. The electrocatalytic activity of the PdAu/Nf–GR catalyst was examined by cyclic voltametry. It was observed that the as prepared catalyst showed efficient activity and good stability for ethanol electrooxidation in alkaline medium.

  8. Synthesis and electrochemical characteristics of Sn-Sb-Ni alloy composite anode for Li-ion rechargeable batteries

    International Nuclear Information System (INIS)

    Guo Hong; Zhao Hailei; Jia Xidi; Qiu Weihua; Cui Fenge

    2007-01-01

    Micro-scaled Sn-Sb-Ni alloy composite was synthesized from oxides of Sn, Sb and Ni via carbothermal reduction. The phase composition and electrochemical properties of the Sn-Sb-Ni alloy composite anode material were studied. The prepared alloy composite electrode exhibits a high specific capacity and a good cycling stability. The lithiation capacity was 530 mAh g -1 in the first cycle and maintained at 370-380 mAh g -1 in the following cycles. The good electrochemical performance may be attributed to its relatively large particle size and multi-phase characteristics. The former reason leads to the lower surface impurity and thus the lower initial capacity loss, while the latter results in a stepwise lithiation/delithiation behavior and a smooth volume change of electrode in cycles. The Sn-Sb-Ni alloy composite material shows a good candidate anode material for the rechargeable lithium ion batteries

  9. Facile synthesis of core–shell structured PANI-Co_3O_4 nanocomposites with superior electrochemical performance in supercapacitors

    International Nuclear Information System (INIS)

    Hai, Zhenyin; Gao, Libo; Zhang, Qiang; Xu, Hongyan; Cui, Danfeng; Zhang, Zengxing; Tsoukalas, Dimitris; Tang, Jun; Yan, Shubin; Xue, Chenyang

    2016-01-01

    Graphical abstract: - Highlights: • PANI-Co_3O_4 is synthesized by carbon-assisted and in situ polymerization methods. • PANI coating improves the properties of Co_3O_4 affecting electrochemical performance. • The nanocomposites exhibit a high specific capacitance of 1184 F g"−"1 at 1.25 A g"−"1. - Abstract: Core–shell structured PANI-Co_3O_4 nanocomposites for supercapacitor applications were synthesized by combination of carbon-assisted method and in situ polymerization method. The crystalline structure, optical band gap, morphology, and hydrophilic property, as the major factors affecting the performances of supercapacitors, were investigated by X-ray diffraction (XRD), UV–vis spectrophotometry (UV–vis), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and water contact angle (WCA). The core–shell structured PANI-Co_3O_4 nanocomposites are characterized by amorphous PANI, small bandgaps, large surface area and favorable hydrophilicity, which indicates the superior electrochemical performances of the nanocomposites as electrode material for supercapacitors. Cyclic voltammetry (CV), galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS) measurements were conducted in 6 M KOH aqueous solution to evaluate the electrochemical performances. The results shows that core–shell structured PANI-Co_3O_4 nanocomposites exhibit a high specific capacitance of 1184 F g"−"1 at 1.25 A g"−"1, excellent cycling stability of a capacitance retention of 84.9% after 1000 galvanostatic charge/discharge cycles, good electrical conductivity and ion diffusion behavior.

  10. Synthesis and enhanced electrochemical performance of the honeycomb TiO2/LiMn2O4 cathode materials

    DEFF Research Database (Denmark)

    Zhang, J.Y.; Shen, J.X.; Wei, C.B.

    2016-01-01

    angle compare to LiMn2O4, implying that TiO2 doping induced a change of crystal structure. By performing electrochemical measurements, we observed an enhancement of specific capacity (127.28 mAhg−1) and an improvement of cycling stability in the TiO2/LiMn2O4 hybrid materials. After 100 cycles of charge...

  11. Shape-controlled synthesis of Au@Pd core-shell nanoparticles and their corresponding electrochemical properties

    KAUST Repository

    Song, Hyon Min; Anjum, Dalaver H.; Khashab, Niveen M.

    2012-01-01

    The shape-controlled synthesis of Au@Pd core-shell nanoparticles (NPs) was successfully achieved through the emulsion phase generated during the phase transfer from organic to aqueous medium. Contrary to conventional epitaxial growth for obtaining

  12. Green synthesis of cobalt (II, III) oxide nanoparticles using Moringa Oleifera natural extract as high electrochemical electrode for supercapacitors

    Science.gov (United States)

    Matinise, N.; Mayedwa, N.; Fuku, X. G.; Mongwaketsi, N.; Maaza, M.

    2018-05-01

    The research work involved the development of a better, inexpensive, reliable, easily and accurate way for the fabrication of Cobalt (II, III) oxide (Co3O4) nanoparticles through a green synthetic method using Moringa Oleifera extract. The electrochemical activity, crystalline structure, morphology, isothermal behaviour and optical properties of Co3O4 nanoparticles were studied using various characterization techniques. The X-ray diffraction (XRD) and Energy Dispersive X-ray Spectroscopy (EDS) analysis confirmed the formation of Co3O4 nanoparticles. The pseudo-capacitor behaviour of spinel Co3O4 nanoparticles on Nickel foam electrode was investigated by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) in 3M KOH solution. The CV curve revealed a pairs of redox peaks, indicating the pseudo-capacitive characteristics of the Ni/Co3O4 electrode. EIS results showed a small semicircle and Warburg impedance, indicating that the electrochemical process on the surface electrode is kinetically and diffusion controlled. The charge-discharge results indicating that the specific capacitance Ni/Co3O4 electrode is approximately 1060 F/g at a discharge current density of at 2 A/g.

  13. Facile synthesis and strongly microstructure-dependent electrochemical properties of graphene/manganese dioxide composites for supercapacitors

    Science.gov (United States)

    Zhang, Caiyun; Zhu, Xiaohong; Wang, Zhongxing; Sun, Ping; Ren, Yinjuan; Zhu, Jiliang; Zhu, Jianguo; Xiao, Dingquan

    2014-09-01

    Graphene has attracted much attention since it was firstly stripped from graphite by two physicists in 2004, and the supercapacitor based on graphene has obtained wide attention and much investment as well. For practical applications of graphene-based supercapacitors, however, there are still many challenges to solve, for instance, to simplify the technological process, to lower the fabrication cost, and to improve the electrochemical performance. In this work, graphene/MnO2 composites are prepared by a microwave sintering method, and we report here a relatively simple method for the supercapacitor packaging, i.e., dipping Ni-foam into a graphene/MnO2 composite solution directly for a period of time to coat the active material on a current collector. It is found that the microwave reaction time has a significant effect on the microstructure of graphene/MnO2 composites, and consequently, the electrochemical properties of the supercapacitors based on graphene/MnO2 composites are strongly microstructure dependent. An appropriately longer microwave reaction time, namely, 15 min, facilitates a very dense and homogeneous microstructure of the graphene/MnO2 composites, and thus, excellent electrochemical performance is achieved in the supercapacitor device, including a high specific capacitance of 296 F/g and a high capacitance retention of 93% after 3,000 times of charging/discharging cycles.

  14. Facile synthesis of cuprous oxide nanowires decorated graphene oxide nanosheets nanocomposites and its application in label-free electrochemical immunosensor.

    Science.gov (United States)

    Wang, Huan; Zhang, Yong; Wang, Yulan; Ma, Hongmin; Du, Bin; Wei, Qin

    2017-01-15

    In this work, the assembly between one-dimensional (1D) nanomaterials and two-dimensional (2D) nanomaterials was achieved by a simple method. Cuprous oxide nanowires decorated graphene oxide nanosheets (Cu 2 O@GO) nanocomposites were synthesized for the first time by a simple electrostatic self-assembly process. The nanostructure was well confirmed by scanning electron microscope (SEM) and transmission electron microscope (TEM) images. Taking advantages of good electrocatalytic activity and high specific surface area of Cu 2 O@GO nanocomposites, a label-free electrochemical immunosensor was developed by employing Cu 2 O@GO as signal amplification platform for the quantitative detection of alpha fetoprotein (AFP). In addition, toluidine blue (TB) was used as the electron transfer mediator to provide the electrochemical signal, which was adsorbed on graphene oxide nanosheets (GO NSs) by electrostatic attraction. The detection mechanism was based on the monitoring of the electrochemical current response change of TB by the square wave voltammetry (SWV) when immunoreaction occurred on the surface of electrode. Under optimal conditions, the proposed immunosensor displayed a high sensitivity and a low detection limit. This designed method may provide an effective method in the clinical diagnosis of AFP and other tumor markers. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Facile synthesis and strongly microstructure-dependent electrochemical properties of graphene/manganese dioxide composites for supercapacitors

    Science.gov (United States)

    2014-01-01

    Graphene has attracted much attention since it was firstly stripped from graphite by two physicists in 2004, and the supercapacitor based on graphene has obtained wide attention and much investment as well. For practical applications of graphene-based supercapacitors, however, there are still many challenges to solve, for instance, to simplify the technological process, to lower the fabrication cost, and to improve the electrochemical performance. In this work, graphene/MnO2 composites are prepared by a microwave sintering method, and we report here a relatively simple method for the supercapacitor packaging, i.e., dipping Ni-foam into a graphene/MnO2 composite solution directly for a period of time to coat the active material on a current collector. It is found that the microwave reaction time has a significant effect on the microstructure of graphene/MnO2 composites, and consequently, the electrochemical properties of the supercapacitors based on graphene/MnO2 composites are strongly microstructure dependent. An appropriately longer microwave reaction time, namely, 15 min, facilitates a very dense and homogeneous microstructure of the graphene/MnO2 composites, and thus, excellent electrochemical performance is achieved in the supercapacitor device, including a high specific capacitance of 296 F/g and a high capacitance retention of 93% after 3,000 times of charging/discharging cycles. PACS 81.05.ue; 78.67.Sc; 88.80.fh PMID:25258609

  16. Facile synthesis of Co(OH)2/Al(OH)3 nanosheets with improved electrochemical properties for asymmetric supercapacitor

    Science.gov (United States)

    Zhao, Cuimei; Ren, Fang; Cao, Yang; Xue, Xiangxin; Duan, Xiaoyue; Wang, Hairui; Chang, Limin

    2018-01-01

    Sheet-like Co(OH)2/Al(OH)3 or Co(OH)2 nanomaterial has been synthesized on conducting carbon fiber paper (CFP) by a facile one-step electrochemical deposition. The binder-free Co(OH)2/Al(OH)3/CFP displays an improved electrical conductivity, electrochemical activity and material utilization than solitary Co(OH)2, therefore Co(OH)2/Al(OH)3 nanomaterial exhibits improved electrochemical properties (a maximum capacitance of 1006 Fg-1 at 2 Ag-1, with 77% retention even at a high current density of 32 Ag-1, and more than 87% of the capacitance retention after 10000 cycles at 32 Ag-1) in comparison to that of the Co(OH)2/CFP (709 Fg-1, 65%, 79%). In addition, an asymmetric supercapacitor (ASC) fabricated with Co(OH)2/Al(OH)3/CFP positive electrode and AC/CFP negative electrode demonstrates ultrahigh specific capacitance (75.8 Fg-1) and potential window (1.7 V). These encouraging results make these low-cost and eco-friendly materials promising for high-performance energy storage application.

  17. Synthesis and electrochemical properties of Ti-doped DLC films by a hybrid PVD/PECVD process

    Science.gov (United States)

    Jo, Yeong Ju; Zhang, Teng Fei; Son, Myoung Jun; Kim, Kwang Ho

    2018-03-01

    Low electrical conductivity and poor adhesion to metallic substrates are the main drawbacks of diamond-like carbon (DLC) films when used in electrode applications. In this study, Ti-doped DLC films with various Ti contents were synthesized on metal Ti substrates by a hybrid PVD/PECVD process, where PECVD was used for deposition of DLC films and PVD was used for Ti doping. The effects of the Ti doping ratio on the microstructure, adhesion strength, and electrical and electrochemical properties of the DLC films were systematically investigated. An increase in the Ti content led to increased surface roughness and a higher sp2/sp3 ratio of the Ti-DLC films. Ti atoms existed as amorphous-phase Ti carbide when the Ti doping ratio was less than 2.8 at.%, while the nanocrystalline TiC phase was formed in DLC films when the Ti doping ratio was exceeded 4.0 at.%. The adhesion strength, electrical resistivity, electrochemical activity and reversibility of the DLC films were greatly improved by Ti doping. The influence of Ti doping ratio on the electrical and electrochemical properties of the DLC films were also investigated and the best performance was obtained at a Ti content of 2.8 at.%.

  18. Synthesis of Ni(OH)2 Nanoflakes Through a Novel Ion Diffusion Method Controlled by Ion Exchange Membrane and Electrochemical Supercapacitive Properties

    International Nuclear Information System (INIS)

    Zhao, Jiangshan; Zhang, Qiang

    2015-01-01

    Highlights: • We synthesized β-Ni(OH) 2 nanoflakes through a novel ion diffusion method. • The possible formation mechanism of the Ni(OH) 2 nanoflakes was discussed. • The temperature influence on growth of Ni(OH) 2 nanocrystals and its subsequent effect on electrochemical supercapacitive properties were examined. • The β-Ni(OH) 2 nanoflakes prepared at 50 °C for 12 h exhibits the highest specific capacitance of 2102 F g −1 . - Abstract: A novel method, ion diffusion method controlled by ion exchange membrane was reported for the synthesis of Ni(OH) 2 nanomaterials in the absence of any template or organic surfactant. The structure and morphology of as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), BET specific surface area and pore size distribution analyzer. It can be observed that β-Ni(OH) 2 nanoflake-like structure was obtained, and the sheet size, thickness and pore size of as-prepared samples can be controlled by altering reaction time and reaction temperature. The BET specific surface area of Ni(OH) 2 nanomaterials obtained by this method can be up to 280.5 m 2 /g at 30 °C. The electrochemical supercapacitive properties of Ni(OH) 2 nanostructures have been investigated by cyclic voltammetry, chronopotentiometry and electrochemical impedance spectroscopy techniques. All these Ni(OH) 2 samples exhibit good capacity for electrochemical supercapacitor in KOH electrolyte. The flake nanostructures synthesized at 50 °C for 12 h exhibit a highest specific capacitance of 2102 F g −1 at a current density of 20 mA cm −2 within the potential range of 0.5 V and the Ni(OH) 2 sample retains 85.1% of the initial capacitance even after 1000 continuous charge–discharge cycles. The results indicate that ion diffusion method controlled by ion exchange membrane is a useful method for synthesizing inorganic nanomaterials.

  19. Synthesis of bismuth sulfide/reduced graphene oxide composites and their electrochemical properties for lithium ion batteries

    International Nuclear Information System (INIS)

    Zhang, Zhian; Zhou, Chengkun; Huang, Lei; Wang, Xiwen; Qu, Yaohui; Lai, Yanqing; Li, Jie

    2013-01-01

    Graphical abstract: The Bi 2 S 3 /reduced graphene oxide composites were synthesized by a one-pot hydrothermal route and exhibited an extraordinary capacity of 1073.1 mAh g −1 with excellent cycling stability and high rate capability as anode material of lithium ion battery. The enhancement in the electrochemical performance could be attributed to the introduction of RGO sheets that not only buffer the large volume changes during the alloy/dealloy reaction of Li and Bi, but also provide a highly conductive network for rapid electron transport in electrode during electrochemical reaction. -- Highlights: •Bi 2 S 3 /RGO composites were in situ prepared by one-pot hydrothermal route. •The Bi 2 S 3 nanoparticles are homogeneous dispersion on the RGO sheets. •Bi 2 S 3 /RGO exhibits excellent cycling stability and high rate capability. •This work will also of interest for supercapacitor and solar cells. -- Abstract: A simple one-pot hydrothermal route was developed to synthesize bismuth sulfide/reduced graphene oxide composites (Bi 2 S 3 /RGO composites) in this work. The morphology and crystalline structure of the obtained products were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and high resolution transmission electron microscopy (HRTEM). The results of Raman spectra and Fourier transform infrared (FTIR) spectra demonstrated that graphite oxide (GO) sheets were in situ reduced to a certain extent. Transmission electron microscopy (TEM) observation indicated that the Bi 2 S 3 nanoparticles, with a size of 80–100 nm in length, are anchored on RGO sheets. Electrochemical tests show the Bi 2 S 3 /RGO composite exhibits an extraordinary capacity of 1073.1 mAh g −1 with excellent cycling stability and high rate capability compared to pure Bi 2 S 3 particles prepared by a similar route in the absence of GO. The enhancement in the electrochemical performance could be attributed to the introduction of RGO sheets

  20. Freeze drying synthesis of Li{sub 3}MnO{sub 4} cathode material for Li-ion batteries: A physico-electrochemical study

    Energy Technology Data Exchange (ETDEWEB)

    Surace, Yuri; Simões, Mário; Karvonen, Lassi; Yoon, Songhak; Pokrant, Simone [Laboratory Materials for Energy Conversion, EMPA – Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf (Switzerland); Weidenkaff, Anke, E-mail: weidenkaff@imw.uni-stuttgart.de [Materials Chemistry, Institute for Materials Science, University of Stuttgart, Heisenbergstrasse 3, DE-70569 Stuttgart (Germany)

    2015-09-25

    Highlights: • Facilitated synthesis of Li{sub 3}MnO{sub 4} with a smaller thermal budget via freeze drying. • Electrochemical activity enhanced by micro- and nanostructure modifications. • Capacity increase of 30% at 1st discharge versus standard synthesis process. - Abstract: Li{sub 3}MnO{sub 4}, a lithium rich phase containing manganese (V), is a promising cathode material for Li-ion batteries due to its very high theoretical capacity (698 A h kg{sup −1}). Li{sub 3}MnO{sub 4} was synthesized from freeze dried precursors at 398 K. Combined structural, morphological and chemical characterization by XRD, TGA, SEM, TEM and XPS revealed improvements in the micro- and nanostructure in comparison to the material synthesized by a standard solid state chemistry route. The average particle size decreased from 10 μm to 3.5 μm and the average crystallite size from close to 100 nm to around 30 nm. These modifications enhanced the capacity (23% at 10 A kg{sup −1} and up to 31% at 50 A kg{sup −1} with a maximum discharge capacity of 290 A h kg{sup −1}) and the rate capability.

  1. Synthesis, characterization and electrochemical properties of 4.8 V LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} cathode material in lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Chi, Le Ha [Faculty of Engineering Physics and NanoTechnology, College of Technology, 144 Xuan Thuy Road, Hanoi (Viet Nam)] [Vietnamese Academy of Science and Technology, 18 Hoang Quoc Viet Street, Cau Giay District, Hanoi (Viet Nam); Dinh, Nguyen Nang [Faculty of Engineering Physics and NanoTechnology, College of Technology, 144 Xuan Thuy Road, Hanoi (Viet Nam); Brutti, Sergio, E-mail: sergio.brutti@uniroma1.i [Department of Chemistry, University of Rome ' La Sapienza' , P.le Aldo Moro 5, 00185 Rome (Italy); Scrosati, Bruno [Department of Chemistry, University of Rome ' La Sapienza' , P.le Aldo Moro 5, 00185 Rome (Italy)

    2010-07-15

    In this work the synthesis of a nickel doped cubic manganese spinel has been studied for application as cathode material in secondary lithium batteries. Six different experimental approaches have been tested in order to carry out a screening of the various possible synthetic routes. The used synthetic strategies were wet chemistry (WC), solid state (SS), combustion synthesis (CS), cellulose-based sol-gel synthesis (SG-C), ascorbic acid-based sol-gel synthesis (SG-AA) and resorcinol/formaldehyde-based sol-gel synthesis (SG-RF). The goal of our study is to obtain insights about how the synthesis conditions can be modified in order to achieve a material with improved electrochemical performances in such devices, especially in high current operating regimes. The synthesized materials have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), atomic absorption, inductively coupled plasma (ICP-MS) atomic emission spectroscopy, surface area measurements and tested as high voltage cathodes in Li-ion electrochemical devices.

  2. Synthesis of nitrogen doped microporous carbons prepared by activation-free method and their high electrochemical performance

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ki-Seok [Department of Chemistry, Inha University, Incheon 402-751 (Korea, Republic of); Park, Soo-Jin, E-mail: sjpark@inha.ac.kr [Department of Chemistry, Inha University, Incheon 402-751 (Korea, Republic of)

    2011-11-30

    Graphical abstract: This describes the increase of specific capacitance in hybrid electrodes as a function of melamine content. Display Omitted Highlights: > For N-enriched hybrid carbons, co-precursors, PVDF/melamine composites, were used. > Microporous carbons were formed by only carbonization without chemical activation. > The nitrogen content of microporous carbons was controlled by melamine content. > N-doped carbons showed higher specific capacitance compared to microporous carbons. > It was attributed to the easy electron transfer and pseudocapacitance. - Abstract: Nitrogen-doped microporous carbons (N-MCs) were prepared by the carbonization of the polyvinylidene fluoride (PVDF)/melamine mixture without chemical activation. The electrochemical performance of the N-MCs was investigated as a function of PVDF/melamine ratio. It was found that, without additional activation, the N-MCs had a high specific surface area (greater than 560 m{sup 2}/g) because of the micropore formation by the release of fluorine groups. In addition, although the specific surface area decreased, nitrogen groups were increased with increasing melamine content, leading to an enhanced electrochemical performance. Indeed, the N-MCs showed a better electrochemical performance than that of microporous carbons (MCs) prepared by PVDF alone, and the highest specific capacitance (310 F/g) was obtained at a current density of 0.5 A/g, as compared to a value of 248 F/g for MCs. These results indicate that the microporous features of N-MC lead to feasible ion transfer during charge/discharge duration and the presence of nitrogen groups as strong electron donor on the N-MC electrode in electrolyte could provide a pseudocapacitance by the redox reaction.

  3. Synthesis of nitrogen doped microporous carbons prepared by activation-free method and their high electrochemical performance

    International Nuclear Information System (INIS)

    Kim, Ki-Seok; Park, Soo-Jin

    2011-01-01

    Graphical abstract: This describes the increase of specific capacitance in hybrid electrodes as a function of melamine content. Display Omitted Highlights: → For N-enriched hybrid carbons, co-precursors, PVDF/melamine composites, were used. → Microporous carbons were formed by only carbonization without chemical activation. → The nitrogen content of microporous carbons was controlled by melamine content. → N-doped carbons showed higher specific capacitance compared to microporous carbons. → It was attributed to the easy electron transfer and pseudocapacitance. - Abstract: Nitrogen-doped microporous carbons (N-MCs) were prepared by the carbonization of the polyvinylidene fluoride (PVDF)/melamine mixture without chemical activation. The electrochemical performance of the N-MCs was investigated as a function of PVDF/melamine ratio. It was found that, without additional activation, the N-MCs had a high specific surface area (greater than 560 m 2 /g) because of the micropore formation by the release of fluorine groups. In addition, although the specific surface area decreased, nitrogen groups were increased with increasing melamine content, leading to an enhanced electrochemical performance. Indeed, the N-MCs showed a better electrochemical performance than that of microporous carbons (MCs) prepared by PVDF alone, and the highest specific capacitance (310 F/g) was obtained at a current density of 0.5 A/g, as compared to a value of 248 F/g for MCs. These results indicate that the microporous features of N-MC lead to feasible ion transfer during charge/discharge duration and the presence of nitrogen groups as strong electron donor on the N-MC electrode in electrolyte could provide a pseudocapacitance by the redox reaction.

  4. Synthesis, spectroscopic analysis and electrochemical performance of modified β-nickel hydroxide electrode with CuO

    Directory of Open Access Journals (Sweden)

    B. Shruthi

    2017-03-01

    Full Text Available In the present work, a modified β-nickel hydroxide (β-Ni(OH2 electrode material with CuO has been prepared using a co-precipitation method. The structure and property of the modified β-Ni(OH2 with CuO were characterized by X-ray diffraction (XRD, Fourier Transform infra-red (FT-IR, Raman and thermal gravimetric-differential thermal analysis (TG-DTA techniques. The results of the FT-IR spectroscopy and TG-DTA indicate that the modified β-Ni(OH2 electrode materials contain intercalated water molecules and anions. A pasted–type electrode was prepared using nickel hydroxide powder as the main active material on a nickel sheet as a current collector. Cyclic voltammetry (CV and Electrochemical impedance spectroscopy (EIS studies were undertaken to assess the electrochemical behavior of pure β-Ni(OH2 and modified β-Ni(OH2 electrode with CuO in a 6 M KOH electrolyte. The addition of CuO into β-nickel hydroxide was found to enhance the reversibility of the electrode reaction and also increase the separation of the oxidation current peak of the active material from the oxygen evolution current. The modified nickel hydroxide with CuO was also found to exhibit a higher proton diffusion coefficient and a lower charge transfer resistance. These findings suggest that the modified β-Ni(OH2 with CuO possesses an enhanced electrochemical response and thus can be recognized as a promising candidate for battery electrode applications.

  5. One–pot synthesis and electrochemical properties of polyaniline nanofibers through simply tuning acid–base environment of reaction medium

    International Nuclear Information System (INIS)

    Li, Tao; Zhou, Yi; Liang, Banglei; Jin, Dandan; Liu, Na; Qin, Zongyi; Zhu, Meifang

    2017-01-01

    Highlights: •Presenting a facile one–pot approach to prepare polyaniline nanofibers through simply tuning acid–base environment of reaction medium. •Determining the role of aniline oligomers play in the formation of polyaniline nanofibers. •Demonstrating the feasibility of polyaniline nanofibers as high–performance electrode materials for supercapacitors. -- Abstract: A facile and efficient one–pot approach was presented to prepare polyaniline (PANi) nanofibers through simply tuning acid–base environment of reaction medium without the assistance of templates or use of organic solvents, in which aniline oligomers formed in the alkaline solution were used as “seeds” for the oriented growth of PANi chains under acidic conditions. The as–prepared PANi nanofibers were investigated by field–emission scanning electron microscopy, ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy and X–ray diffraction technology. Furthermore, the electrochemical properties were evaluated by cyclic voltammetry, galvanostatic charge–discharge test, and electrochemical impedance spectroscopy. More attentions were paid to the influence of aniline concentrations in alkaline and acidic reaction medium on the morphology, microstructure and properties of PANi nanofibers. It can be found that aniline concentration in alkaline medium has a stronger impact on the electrical and electrochemical properties of final products, however, their morphologies obviously depend on aniline concentration in acidic solution. Moreover, PANi nanofibers prepared at aniline concentrations of 48 mM in alkaline medium and 0.2 M in acidic medium exhibits the largest specific capacitance of 857.2 F g −1 at the scan rate of 5 mV s −1 , and capacitance retention of 63.8% after 500 cycles. It is demonstrated that such one–pot approach can present a low cost and environmental friendly route to fabricate PANi nanofibers in fully aqueous solution as high

  6. Facile surfactant- and template-free synthesis and electrochemical properties of SnO{sub 2}/graphene composites

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jing, E-mail: xy13787103391@126.com [School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Zhang, Xia, E-mail: zyx02090229@163.com [School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Guo, Jianqiang; Peng, Rufang [School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Xie, Ruishi [Analytical and Testing Center, Southwest University of Science and Technology, Mianyang 621010 (China); Huang, Yeju; Qi, Yongcheng [School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China)

    2016-07-25

    In this work, we demonstrate a facile and green hydrothermal process without using any surfactant or template to synthesize SnO{sub 2} nanoflowers (NFs)/graphene nanosheets (GNSs) composites as a high-performance electrode material for electric double layer capacitors (EDLCs). The crystal structure and morphology of the products were characterized by X-ray diffraction, scanning electron microscopy, and transition electron microscopy. The electrochemical properties were investigated by galvanostatic charge/discharge cycling and cycling voltammetry in a voltage range of −0.2–0.8 V. The results exhibit that the addition of GNSs did not change the tetragonal crystal structure of SnO{sub 2}, and the GNSs were successfully coated on the flower-like surface of SnO{sub 2}. The grain morphology of SnO{sub 2}@GNSs composites has a flower-like appearance suggesting excellent electrochemical properties which were confirmed by electrochemical techniques. Compared with the GNSs, the SnO{sub 2}@GNSs composites exhibit a high specific discharge capacitance of 126 F g{sup −1} at 0.2 A g{sup −1} and remains 98.2% after 2000 charge–discharge cycles. The combination of GNSs and SnO{sub 2} could significantly improve the electrical conductivity, enhance the interactions between GNSs and SnO{sub 2} NFs and provide more reaction sites, thereby resulting in improved electrochemical properties for the SnO{sub 2}@GNSs composites in contrast with the pristine GNSs sample. The high specific capacity and long stability make the SnO{sub 2}@GNSs nanocomposite as a electrode material for high-performance supercapacitors. - Highlights: • SnO{sub 2} nanoflowers (NFs)/Graphene nanosheets(GNSs) composites were prepared by a simple and rapid hydrothermal process. • The results show that the GNSs were homogeneously and tightly attached on the surface of SnO{sub 2} NFs. • The SnO{sub 2} NFs/GNSs composites electrode exhibited the enhanced capacitive performances than those of pure GNSs.

  7. Electrochemical synthesis of MoS2 quantum dots embedded nanostructured porous silicon with enhanced electroluminescence property

    Science.gov (United States)

    Shrivastava, Megha; Kumari, Reeta; Parra, Mohammad Ramzan; Pandey, Padmini; Siddiqui, Hafsa; Haque, Fozia Z.

    2017-11-01

    In this report we present the successful enhancement in electroluminescence (EL) in nanostructured n-type porous silicon (PS) with an idea of embedding luminophorous Molybdenum disulfide (MoS2) quantum dots (QD's). Electrochemical anodization technique was used for the formation of PS surface and MoS2 QD's were prepared using the electrochemical route. Spin coating technique was employed for the proper incorporation of MoS2 QD's within the PS nanostructures. The crystallographic analysis was performed using X-ray diffraction (XRD), Raman and Fourier transform infrared (FT-IR) spectroscopy techniques. However, surface morphology was determined using Transmission electron microscopy (TEM) and Atomic force microscopy (AFM). The optical measurements were performed on photoluminescence (PL) spectrophotometer; additionally for electroluminescence (EL) study special arrangement of instrumental setup was made at laboratory level which provides novelty to this work. A diode prototype was made comprising Ag/MoS2:PS/Silicon/Ag for EL study. The MoS2:PS shows a remarkable concentration dependent enhancement in PL as well as in EL intensities, which paves a way to better utilize this strategy in optoelectronic device applications.

  8. In-situ hydrothermal synthesis of three-dimensional MnO2-CNT nanocomposites and their electrochemical properties

    International Nuclear Information System (INIS)

    Teng, Fei; Santhanagopalan, Sunand; Wang, Ying; Meng, Dennis Desheng

    2010-01-01

    Three-dimensional (3-D) MnO 2 -carbon nanotube (CNT) nanocomposites were prepared by a simple one-pot hydrothermal method. An electrode was then prepared with these nanocomposites. For comparative investigation, MnO 2 microspheres were also hydrothermally prepared without adding CNTs. The as-synthesized MnO 2 microspheres were then mechanically mixed with CNTs to prepare a subsequent electrode. The samples were characterized by electron microscopy, X-ray diffraction, and electrochemical methods. It has been revealed that a 3-D conductive network of CNTs was formed with microspheres of MnO 2 nanorods interwoven with and connected by CNTs. As a result, the hydrothermally mixed MnO 2 -CNT electrode showed a higher specific capacitance than the mechanically mixed electrode. It has therefore been concluded that the hydrothermal mixing method yields a more homogeneous product that is better suited to take full advantages of both the high capacitance of MnO 2 and the high electrical conductivity of CNTs. The 3-D MnO 2 -CNT nanocomposites reported herein have provided a promising electrode material for supercapacitors and other electrochemical energy storage/conversion devices.

  9. One-step synthesis of redox-active polymer/AU nanocomposites for electrochemical immunoassay of multiplexed tumor markers.

    Science.gov (United States)

    Liu, Zhimin; Rong, Qinfeng; Ma, Zhanfang; Han, Hongliang

    2015-03-15

    In this work, a simple and sensitive multiplexed immunoassay protocol for simultaneous electrochemical determination of alpha-fetoprotein (AFP) and carcinoembryonic antigen (CEA) was designed using redox-active nanocomposites. As the redox-active species, the poly(o-phenylenediamine) (POPD)/Au nanocomposite and poly(vinyl ferrocene-2-aminothiophenol) (poly(VFc-ATP))/Au nanocomposite were obtained by one-step method which HAuCl4 was used as the oxidant. With Au nanoparticles (AuNPs), the nanocomposites were successful to immobilize labeled anti-CEA and anti-AFP as the immunosensing probes. The proposed electrochemical immunoassay enabled the simultaneous monitoring of AFP and CEA in a wide range of 0.01-100ngmL(-1). The detection limits was 0.006ngmL(-1) for CEA and 0.003ngmL(-1) for AFP (S/N=3). The assay results of serum samples with the proposed method were well consistent with the reference values from standard ELISA method. And the negligible cross-reactivity between the two analytes makes it possesses potential promise in clinical diagnosis. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Microwave synthesis and electrochemical characterization of mesoporous carbon@Bi{sub 2}O{sub 3} composites

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Nannan [Department of Chemistry and Institute of Nanochemistry, Jinan University, Guangzhou 510632 (China); Yuan, Dingsheng, E-mail: tydsh@jnu.edu.cn [Department of Chemistry and Institute of Nanochemistry, Jinan University, Guangzhou 510632 (China); Zhou, Tianxiang; Chen, Jingxing; Mo, Shanshan; Liu, Yingliang [Department of Chemistry and Institute of Nanochemistry, Jinan University, Guangzhou 510632 (China)

    2011-05-15

    Graphical abstract: An efficient and quick microwave method has been employed to prepare worm-like mesoporous carbon@Bi{sub 2}O{sub 3} composites for the first time. The electrochemical measurement shows the worm-like mesoporous carbon@Bi{sub 2}O{sub 3} composites exhibits excellent capacitance performance and the maximum specific capacitance is up to 386 F g{sup -1}. Research highlights: {yields} An efficient and quick microwave method has been employed. {yields} A worm-like mesoporous carbon@Bi{sub 2}O{sub 3} composites have been successfully prepared. {yields} This composite exhibits excellent capacitance performance. {yields} This composite could be a potential electrode material for the supercapacitors. -- Abstract: An efficient and quick microwave method has been employed to prepare worm-like mesoporous carbon@Bi{sub 2}O{sub 3} composites for the first time. As-prepared products have been characterized by X-ray diffraction, N{sub 2} adsorption-desorption, scanning electron microscopy, transmission electron microscopy and inductive coupled plasma atomic emission spectroscopy. The electrochemical measurement shows the worm-like mesoporous carbon@Bi{sub 2}O{sub 3} composites exhibits excellent capacitance performance and the maximum specific capacitance reaches 386 F g{sup -1}, three times more than the pure worm-like mesoporous carbon.

  11. Synthesis and electrochemical properties of olivine LiFePO{sub 4} prepared by a carbothermal reduction method

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Hui-ping; Wang, Zhi-xing; Li, Xin-hai; Guo, Hua-jun; Peng, Wen-jie; Zhang, Yun-he; Hu, Qi-yang [School of Metallurgical Science and Engineering, Central South University, Changsha 410083 (China)

    2008-10-01

    LiFePO{sub 4}/C composite cathode material was prepared by carbothermal reduction method, which uses NH{sub 4}H{sub 2}PO{sub 4}, Li{sub 2}CO{sub 3} and cheap Fe{sub 2}O{sub 3} as starting materials, acetylene black and glucose as carbon sources. The precursor of LiFePO{sub 4}/C was characterized by differential thermal analysis and thermogravimetry. X-ray diffraction (XRD), scanning electron microscopy (SEM) micrographs showed that the LiFePO{sub 4}/C is olivine-type phase, and the addition of the carbon reduced the LiFePO{sub 4} grain size. The carbon is dispersed between the grains, ensuring a good electronic contact. The products sintered at 700 C for 8 h with glucose as carbon source possessed excellent electrochemical performance. The synthesized LiFePO{sub 4} composites showed a high electrochemical capacity of 159.3 mAh g{sup -1} at 0.1C rate, and the capacity fading is only 2.2% after 30 cycles. (author)

  12. Synthesis of feather-like CeO2 microstructures and enzymatic electrochemical catalysis for trichloroacetic acid

    Science.gov (United States)

    Xiao, Xin; Zhang, Dong En; Zhang, Fan; Gong, Jun Yan; Zhang, Xiao Bo; Wang, Yi Hui; Ma, Juan Juan; Tong, Zhi Wei

    Novel feather-like CeO2 microstructures were achieved by a thermal decomposition approach of Ce(OH)CO3 precursor. The Ce(OH)CO3 was obtained from a solvothermal method employing Ce(NO3)3.6H2O with C6H12N4 and C16H33(CH3)3NBr (CTAB) at 190∘C in a water-PEG-200 mixed solution. The feather-like CeO2 dendrite was obtained by thermal conversion of the feather-like Ce(OH)CO3 at 650∘C in air. A reasonable growth mechanism was proposed with the soft-template effect of PEG-200. The electrochemical behavior and enzyme activity of myoglobin (Mb) immobilized on CeO2-Nafion modified glassy carbon electrode (GCE) are demonstrated by cyclic voltammetric measurements. The results indicate that CeO2 can obviously promote the direct electron transfer between the Mb redox centers and the electrode. The Mb on CeO2-Nafion behaves as an elegant performance on the electrochemical reduction of trichloroacetic acid (TCA) from 0.32μM to 2.28μM. The detection limit is estimated to be 0.08μM.

  13. Efficient solar-driven synthesis, carbon capture, and desalinization, STEP: solar thermal electrochemical production of fuels, metals, bleach

    Energy Technology Data Exchange (ETDEWEB)

    Licht, S. [Department of Chemistry, George Washington University, Washington, DC (United States)

    2011-12-15

    STEP (solar thermal electrochemical production) theory is derived and experimentally verified for the electrosynthesis of energetic molecules at solar energy efficiency greater than any photovoltaic conversion efficiency. In STEP the efficient formation of metals, fuels, chlorine, and carbon capture is driven by solar thermal heated endothermic electrolyses of concentrated reactants occuring at a voltage below that of the room temperature energy stored in the products. One example is CO{sub 2}, which is reduced to either fuels or storable carbon at a solar efficiency of over 50% due to a synergy of efficient solar thermal absorption and electrochemical conversion at high temperature and reactant concentration. CO{sub 2}-free production of iron by STEP, from iron ore, occurs via Fe(III) in molten carbonate. Water is efficiently split to hydrogen by molten hydroxide electrolysis, and chlorine, sodium, and magnesium from molten chlorides. A pathway is provided for the STEP decrease of atmospheric carbon dioxide levels to pre-industrial age levels in 10 years. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Nanometric MgFe2O4: Synthesis, characterization and its application towards supercapacitor and electrochemical uric acid sensor

    Science.gov (United States)

    Majumder, S.; Kumar, S.; Banerjee, S.

    2017-05-01

    In this paper, we have synthesized nanocrystalline MgFe2O4 (S1) by auto-combustion assisted sol-gel method. The structure and morphology and elemental study of S1 are examined by powder X-ray diffraction (PXRD), field emission scanning electron microscopic (FESEM) and energy dispersive X-ray spectroscopic (EDS) techniques. The FESEM images reveal that the morphology of the sample is rough and average particle size is 50 nm. The PXRD study indicates that the samples are well crystalline and single phase in nature. Moreover, we have performed supercapacitor study by electrochemical galvanostatic charge-discharge (GCD) measurement, which shows pseudo capacitive behavior. S1 contains a high specific capacitance of 428.9 Fg-1 at the current density 0.0625 Ag-1 and can deliver high energy and power density of 18.01 Wh kg-1 and 21468 Wkg-1 respectively. Moreover, uric acid (UA) sensing study has also been performed by cyclic voltmetry (CV) and electrochemical impedance spectroscopy measurement (EIS) of S1. We can use nanocrystalline MgFe2O4 as supercapacitor and UA sensor applications purpose.

  15. In-situ hydrothermal synthesis of three-dimensional MnO{sub 2}-CNT nanocomposites and their electrochemical properties

    Energy Technology Data Exchange (ETDEWEB)

    Teng, Fei; Santhanagopalan, Sunand [Department of Mechanical Engineering-Engineering Mechanics, Michigan Technological University, Houghton, MI 49931 (United States); Wang, Ying [Department of Mechanical Engineering, Louisiana State University, Baton Rouge, LA 70803 (United States); Meng, Dennis Desheng, E-mail: dmeng@mtu.ed [Department of Mechanical Engineering-Engineering Mechanics, Michigan Technological University, Houghton, MI 49931 (United States)

    2010-06-11

    Three-dimensional (3-D) MnO{sub 2}-carbon nanotube (CNT) nanocomposites were prepared by a simple one-pot hydrothermal method. An electrode was then prepared with these nanocomposites. For comparative investigation, MnO{sub 2} microspheres were also hydrothermally prepared without adding CNTs. The as-synthesized MnO{sub 2} microspheres were then mechanically mixed with CNTs to prepare a subsequent electrode. The samples were characterized by electron microscopy, X-ray diffraction, and electrochemical methods. It has been revealed that a 3-D conductive network of CNTs was formed with microspheres of MnO{sub 2} nanorods interwoven with and connected by CNTs. As a result, the hydrothermally mixed MnO{sub 2}-CNT electrode showed a higher specific capacitance than the mechanically mixed electrode. It has therefore been concluded that the hydrothermal mixing method yields a more homogeneous product that is better suited to take full advantages of both the high capacitance of MnO{sub 2} and the high electrical conductivity of CNTs. The 3-D MnO{sub 2}-CNT nanocomposites reported herein have provided a promising electrode material for supercapacitors and other electrochemical energy storage/conversion devices.

  16. A role of nanotube dangling pyrrole and oxygen functions in the electrochemical synthesis of polypyrrole/MWCNTs hybrid materials

    International Nuclear Information System (INIS)

    Krukiewicz, Katarzyna; Herman, Artur P.; Turczyn, Roman; Szymańska, Katarzyna; Koziol, Krzysztof K.K.; Boncel, Sławomir; Zak, Jerzy K.

    2014-01-01

    Highlights: • The effect of MWCNT functionalization on properties of PPy composites was explained. • The behavior of pristine, pyrrole-modified and oxidized MWCNT was explained. • Functionalization of MWCNT improved their dispersibility and processability. • Different mechanisms of (f-)MWCNT incorporation into PPy composites were explained. • Orientation of growing PPy chains was tailored through the addition of (f-)MWCNT. - Abstract: The effect of the functionalization of multi-walled carbon nanotubes (MWCNTs) on the process of electrochemical co-deposition of MWCNTs and polypyrrole (PPy), as well as the morphology of obtained composites have been demonstrated. As the nanotube components of the hybrids, three types of MWCNT were used, namely c-CVD derived (pristine) MWCNTs, their oxidized counterparts MWCNT-Ox and pyrrole-modified MWCNT-Py. The stability of pristine and functionalized MWCNTs (f-MWCNT) dispersions in tetrahydrofuran and water was studied together with the description of the process of formation PPy/(f-)MWCNT hybrid materials via electrochemical co-deposition. The structural and morphological properties of the hybrids were characterized by Raman spectroscopy, scanning electron microscopy and atomic force microscopy revealing substantial differences among hybrid materials in their surface morphology and the influence of MWCNT functionalization on the orientation of growing PPy chains

  17. A role of nanotube dangling pyrrole and oxygen functions in the electrochemical synthesis of polypyrrole/MWCNTs hybrid materials

    Energy Technology Data Exchange (ETDEWEB)

    Krukiewicz, Katarzyna, E-mail: katarzyna.krukiewicz@polsl.pl [Department of Physical Chemistry and Technology of Polymers, Silesian University of Technology, Strzody 9, 44-100 Gliwice (Poland); Herman, Artur P., E-mail: artur.herman@polsl.pl [Department of Organic Chemistry, Bioorganic Chemistry and Biotechnology, Silesian University of Technology, Krzywoustego 4, Gliwice 44-100 (Poland); Turczyn, Roman, E-mail: roman.turczyn@polsl.pl [Department of Physical Chemistry and Technology of Polymers, Silesian University of Technology, Strzody 9, 44-100 Gliwice (Poland); Szymańska, Katarzyna, E-mail: katarzyna.szymanska@polsl.pl [Department of Chemical and Process Engineering, Silesian University of Technology, Strzody 7, 44-100 Gliwice (Poland); Koziol, Krzysztof K.K., E-mail: kk292@cam.ac.uk [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Boncel, Sławomir, E-mail: slawomir.boncel@polsl.pl [Department of Organic Chemistry, Bioorganic Chemistry and Biotechnology, Silesian University of Technology, Krzywoustego 4, Gliwice 44-100 (Poland); Zak, Jerzy K., E-mail: jerzy.zak@polsl.pl [Department of Physical Chemistry and Technology of Polymers, Silesian University of Technology, Strzody 9, 44-100 Gliwice (Poland)

    2014-10-30

    Highlights: • The effect of MWCNT functionalization on properties of PPy composites was explained. • The behavior of pristine, pyrrole-modified and oxidized MWCNT was explained. • Functionalization of MWCNT improved their dispersibility and processability. • Different mechanisms of (f-)MWCNT incorporation into PPy composites were explained. • Orientation of growing PPy chains was tailored through the addition of (f-)MWCNT. - Abstract: The effect of the functionalization of multi-walled carbon nanotubes (MWCNTs) on the process of electrochemical co-deposition of MWCNTs and polypyrrole (PPy), as well as the morphology of obtained composites have been demonstrated. As the nanotube components of the hybrids, three types of MWCNT were used, namely c-CVD derived (pristine) MWCNTs, their oxidized counterparts MWCNT-Ox and pyrrole-modified MWCNT-Py. The stability of pristine and functionalized MWCNTs (f-MWCNT) dispersions in tetrahydrofuran and water was studied together with the description of the process of formation PPy/(f-)MWCNT hybrid materials via electrochemical co-deposition. The structural and morphological properties of the hybrids were characterized by Raman spectroscopy, scanning electron microscopy and atomic force microscopy revealing substantial differences among hybrid materials in their surface morphology and the influence of MWCNT functionalization on the orientation of growing PPy chains.

  18. A High Molar Extinction Coefficient Mono-Anthracenyl Bipyridyl Heteroleptic Ruthenium(II Complex: Synthesis, Photophysical and Electrochemical Properties

    Directory of Open Access Journals (Sweden)

    Peter A. Ajibade

    2011-06-01

    Full Text Available In our quest to develop good materials as photosensitizers for photovoltaic dye-sensitized solar cells (DSSCs, cis-dithiocyanato-4-(2,3-dimethylacrylic acid-2,2'-bipyridyl-4-(9-anthracenyl-(2,3-dimethylacrylic-2,2'-bipyridyl ruthenium(II complex, a high molar extinction coefficient charge transfer sensitizer, was designed, synthesized and characterized by spectroscopy and electrochemical techniques. Earlier studies on heteroleptic ruthenium(II complex analogues containing functionalized oligo-anthracenyl phenanthroline ligands have been reported and documented. Based on a general linear correlation between increase in the length of π-conjugation bond and the molar extinction coefficients, herein, we report the photophysical and electrochemical properties of a Ru(II bipyridyl complex analogue with a single functionalized anthracenyl unit. Interestingly, the complex shows better broad and intense metal-to ligand charge transfer (MLCT band absorption with higher molar extinction coefficient (λmax = 518 nm, e = 44900 M−1cm−1, and appreciable photoluminescence spanning the visible region than those containing higher anthracenyl units. It was shown that molar absorption coefficient of the complexes may not be solely depended on the extended π-conjugation but are reduced by molecular aggregation in the molecules.

  19. Synthesis and characterization of pulsed polymerized poly(3,4-ethylenedioxythiophene) electrodes for high-performance electrochemical capacitors

    International Nuclear Information System (INIS)

    Pandey, G.P.; Rastogi, A.C.

    2013-01-01

    Poly(3,4-ethylenedioxythiophene) (PEDOT) is electrochemically prepared as a film on flexible thin graphite substrate by short galvanic pulse method in organic media. For comparative studies, PEDOT films are also prepared by potentiostatic polymerization method. The nucleation and growth mechanism for PEDOT film polymerized by short current pulses is presented with morphological and structural studies. The growth of PEDOT is continuous during the pulse off period as confirmed by the deposited mass of PEDOT by these two different methods. The SEM studies of pulse polymerized PEDOT films with different pulse on time show the features of highly porous and ridge like structures which help in rapid migration of dopant ClO 4 − ions during the charge and discharge processes. The X-ray photoelectron spectroscopy (XPS) studies confirm that in the pulse polymerized PEDOT films polymer chains are fully conjugated with the dopant ClO 4 − ions. The electrochemical characterization of PEDOT films show that pulse polymerized PEDOT films exhibited high specific capacitance (126.5 F g −1 ) with an improved energy density and rate kinetics as comparison to the potentiostatically deposited PEDOT films (100 F g −1 ) in aqueous electrolyte.

  20. Studies on the electrochemical behavior of heavy lanthanide ions and the synthesis, characterization of heavy metal chelate complexes

    International Nuclear Information System (INIS)

    Kang, Sam Woo; Chang, Choo Hwan; Son, Byung Chan; Suh, Moo Yul; Kim, Chae Kyun

    1991-01-01

    Electrochemical behavior of some heavy lanthanide ions(Gd 3+ , Tb 3+ , Dy 3+ , Ho 3+ , Er 3+ , Tm 3+ , Yb 3+ and Lu 3+ ) in various supporting electrolytes has been investigated by dc polarography, differential pulse polarography and cyclic voltammetry. The peak potentials and the peak currents, their dependency on the concentration and pH effects, the reversibility of the electrode reactions are described. The reduction of Gd 3+ , Tb 3+ , Dy 3+ , Ho 3+ , Er 3+ , Tm 3+ and Lu 3+ ions in 0.1M lithium chloride solution proceeds by a three-electron change directly to the metallic state, whereas the reduction of Yb 3+ proceeds by a one-electron change followed by a two-electron change. It was found that, in differential pulse polarography and cyclic voltammetry, the peak potential, peak current and current function showed constant value in the pH range of 4.0-6.0 by varying pH and scan rates. And also the current function is found to decrease as the sweep rate is increased when the pH reaches 4.0. This fact may indicate a chemical reaction coupled with the electrochemical reaction at lower pH values(pH 3+ ion is possible to determine voltammetrically within the error of ±3.5% in the presence of other competitive lanthanide ions. (Author)

  1. In situ one-pot synthesis of graphene–polyaniline nanofiber composite for high-performance electrochemical capacitors

    International Nuclear Information System (INIS)

    Jin, Yuhong; Fang, Mou; Jia, Mengqiu

    2014-01-01

    In this work, graphene–polyaniline nanofiber (G/PANI-F) composite is prepared through a new and one-pot method that includes the reduction of graphene oxide (GO) by aniline and then followed by in-situ polymerization. Aniline plays the two roles in this method: as a chemical reducing agent to reduce GO to graphene and as a monomer to prepare polyaniline nanofiber (PANI-F). Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectra, X-ray photoelectron spectroscopy and transmission electron microscopy are employed to confirm that GO can be reduced by aniline and PANI-F can be deposited on the surface of graphene. The electrochemical properties of G/PANI-F composite electrode are measured by using cyclic voltammetry, galvanostatic charge–discharge test and electrochemical impedance spectroscopy. The G/PANI-F composite electrode exhibits enhanced specific capacitance of 965 F g −1 at 0.5 A g −1 and the capacity retention is 90% after 2000 cycles.

  2. Synthesis and characterization of NiCo_2O_4 nanoplates as efficient electrode materials for electrochemical supercapacitors

    International Nuclear Information System (INIS)

    Kim, Taehyun; Ramadoss, Ananthakumar; Saravanakumar, Balasubramaniam; Veerasubramani, Ganesh Kumar; Kim, Sang Jae

    2016-01-01

    Highlights: • NiCo_2O_4 nanoplates were synthesized through a facile approach. • The NiCo_2O_4 nanoplates electrode material exhibit a specific capacitance of 332 F g"−"1 at 5 mV s"−"1. • The fabricated NiCo_2O_4 electrode reveals 86% retention of initial capacitance after 2000 cycles. - Abstract: In the present work, NiCo_2O_4 nanoplates were prepared by a facile, low temperature, hydrothermal method, followed by thermal annealing and used supercapacitor applications. The physico-chemical characterization of as-prepared materials were investigated by means of X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FT-IR) and field emission scanning electron microscopy (FE-SEM). The electrochemical measurements demonstrate that the NiCo_2O_4 nanoplates electrode (NC-5) exhibits a high specific capacitance of 332 F g"−"1 at a scan rate of 5 mV s"−"1 and also retained about 86% of the initial specific capacitance value even after 2000 cycles at a current density of 2.5 A g"−"1. These results suggest that the fabricated electrode material has huge potential as a novel electrode material for electrochemical capacitors.

  3. Synthesis and electrochemical study of a hybrid structure based on PDMS-TEOS and titania nanotubes for biomedical applications

    International Nuclear Information System (INIS)

    Castro, António G B; Bastos, Alexandre C; Miranda Salvado, Isabel M; Galstyan, Vardan; Faglia, Guido; Sberveglieri, Giorgio

    2014-01-01

    Metallic implants and devices are widely used in the orthopedic and orthodontic clinical areas. However, several problems regarding their adhesion with the living tissues and inflammatory responses due to the release of metallic ions to the medium have been reported. The modification of the metallic surfaces and the use of biocompatible protective coatings are two approaches to solve such issues. In this study, in order to improve the adhesion properties and to increase the corrosion resistance of metallic Ti substrates we have obtained a hybrid structure based on TiO 2 nanotubular arrays and PDMS-TEOS films. TiO 2 nanotubes have been prepared with two different diameters by means of electrochemical anodization. PDMS-TEOS films have been prepared by the sol–gel method. The morphological and the elemental analysis of the structures have been investigated by scanning electron microscopy and energy dispersive spectroscopy (EDS). Electrochemical impedance spectroscopy (EIS) and polarization curves have been performed during immersion of the samples in Kokubo’s simulated body fluid (SBF) at 37 °C to study the effect of structure layers and tube diameter on the protective properties. The obtained results show that the modification of the surface structure of TiO 2 and the application of PDMS-TEOS film is a promising strategy for the development of implant materials. (paper)

  4. Shape-controlled synthesis of Au@Pd core-shell nanoparticles and their corresponding electrochemical properties

    KAUST Repository

    Song, Hyon Min

    2012-01-01

    The shape-controlled synthesis of Au@Pd core-shell nanoparticles (NPs) was successfully achieved through the emulsion phase generated during the phase transfer from organic to aqueous medium. Contrary to conventional epitaxial growth for obtaining core-shell structures, this method does not require high temperatures and does not have shape restrictions. © 2012 The Royal Society of Chemistry.

  5. Synthesis and application of bismuth ferrite nanosheets supported functionalized carbon nanofiber for enhanced electrochemical detection of toxic organic compound in water samples.

    Science.gov (United States)

    Ramaraj, Sukanya; Mani, Sakthivel; Chen, Shen-Ming; Kokulnathan, Thangavelu; Lou, Bih-Show; Ali, M Ajmal; Hatamleh, A A; Al-Hemaid, Fahad M A

    2018-03-15

    Recently, the multiferroic material has fabulous attention in numerous applications owing to its excellent electronic conductivity, unique mechanical property, and higher electrocatalytic activity, etc. In this paper, we reported that the synthesis of bismuth ferrite (BiFeO 3 ) nanosheets integrated functionalized carbon nanofiber (BiFeO 3 NS/F-CNF) nanocomposite using a simple hydrothermal technique. Herein, the structural changes and crystalline property of prepared BiFeO 3 NS/F-CNF nanocomposite were characterized using Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). From this detailed structural evolution, the formation of nanosheets like BiFeO 3 and its nanocomposite with F-CNF were scrutinized and reported. Furthermore, the as-prepared BiFeO 3 NS/F-CNF nanocomposite modified glassy carbon electrode (GCE) was applied for electrochemical detection of catechol (CC). As expected, BiFeO 3 NS/F-CNF/GCE shows excellent electrocatalytic activity as well as 3.44 (F-CNF/GCE) and 7.92 (BiFeO 3 NS/GCE) fold higher electrochemical redox response for CC sensing. Moreover, the proposed sensor displays a wide linear range from 0.003 to 78.02 µM with a very low detection limit of 0.0015 µM. In addition, we have validated the real-time application of our developed CC sensor in different water samples. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Self-template synthesis of double shelled ZnS-NiS1.97 hollow spheres for electrochemical energy storage

    Science.gov (United States)

    Wei, Chengzhen; Ru, Qinglong; Kang, Xiaoting; Hou, Haiyan; Cheng, Cheng; Zhang, Daojun

    2018-03-01

    In this work, double shelled ZnS-NiS1.97 hollow spheres have been achieved via a simple self-template route, which involves the synthesis of Zn-Ni solid spheres precursors as the self-template and then transformation into double shelled ZnS-NiS1.97 hollow spheres by sulfidation treatment. The as-prepared double shelled ZnS-NiS1.97 hollow spheres possess a high surface area (105.26 m2 g-1) and porous structures. Benefiting from the combined characteristics of novel structures, multi-component, high surface area and porous. When applied as electrode materials for supercapacitors, the double shelled ZnS-NiS1.97hollow spheres deliver a large specific capacitance of 696.8C g-1 at 5.0 A g-1 and a remarkable long lifespan cycling stability (less 5.5% loss after 6000 cycles). Moreover, an asymmetric supercapacitor (ASC) was assembled by utilizing ZnS-NiS1.97 (positive electrode) and activated carbon (negative electrode) as electrode materials. The as-assembled device possesses an energy density of 36 W h kg-1, which can be yet retained 25.6 W h kg-1 even at a power density of 2173.8 W Kg-1, indicating its promising applications in electrochemical energy storage. More importantly, the self-template route is a simple and versatile strategy for the preparation of metal sulfides electrode materials with desired structures, chemical compositions and electrochemical performances.

  7. Facile Synthesis of Boron-doped Graphene Nanosheets with Hierarchical Microstructure at Atmosphere Pressure for Metal-free Electrochemical Detection of Hydrogen Peroxide

    International Nuclear Information System (INIS)

    Yeh, Min-Hsin; Li, Yan-Sheng; Chen, Guan-Lin; Lin, Lu-Yin; Li, Ta-Jen; Chuang, Hui-Min; Hsieh, Cheng-Yu; Lo, Shen-Chuan; Chiang, Wei-Hung; Ho, Kuo-Chuan

    2015-01-01

    Graphical abstract: Display Omitted -- Highlights: • B-doped graphene nanosheets (BGNs) were used as a catalyst for sensing H 2 O 2 . • BGNs were synthesized by an atmospheric-pressure carbothermal reaction. • BGNs with hierarchical microstructure provide more electron transport pathways. • B atoms act as the active sites by transferring charges to neighboring C atoms. • Electrocatalytic ability of BGNs was characterized by a rotating disk electrode. -- Abstract: Hydrogen peroxide (H 2 O 2 ) is an essential mediator for most of the oxidative biological reactions in enzyme-based biosensor systems, such as glucose oxidase, cholesterol oxidase, and alcohol oxidase. Synthesis of new catalysts to detect the concentration of H 2 O 2 more precisely is indispensable for enzyme-based electrochemical biosensors. In this study, boron-doped graphene nanosheets (BGNs) with 2.2 atomic percentage (at%) boron doping level and a hierarchical microstructure were synthesized by an atmospheric-pressure carbothermal reaction as a noble-metal free catalyst for sensing H 2 O 2 . The isolated boron atoms on the BGNs surface act as the electrocatalytic sites by transferring charges to neighbor carbon atoms, and the hierarchical microstructure provides multidimensional electron transport pathways for charge transfer and therefore enhances the electrocatalytic ability. BGNs possess a higher reduction current in the cyclic voltammetry (CV) measurement than that of pristine graphene nanosheets (GNs) over the detection range of 0.0 to 10.0 mM at −0.4 V (vs. Ag/AgCl). The BGNs modified electrochemical sensor shows a linear range from 1.0 to 20.0 mM of H 2 O 2 with a sensitivity of 266.7 ± 3.8 μA mM −1 cm −2 and limit of detection (LOD) of 3.8 μM at a signal-to-noise (S/N) ratio of 3. The beneficial hierarchical microstructure and the synergetic effects arising from doping boron in GNs accomplish the better performance of the BGNs modified electrochemical sensor

  8. Synthesis and electrochemical properties of ZnMn_2O_4 anode for lithium-ion batteries

    International Nuclear Information System (INIS)

    Feng, Chuanqi; Wang, Wei; Chen, Xiao; Wang, Shiquan; Guo, Zaiping

    2015-01-01

    Graphical abstract: ZnMn_2O_4 nanoparticles were prepared through the rheological phase reaction method (R-ZMO) or the mixed solvothermal method(M-ZMO). The particles of M-ZMO were clustered together to form uniform microspheres morphology. The M-ZMO behaved higher reversible capacity and better cycle performance than that of R-ZMO. - Highlights: • ZnMn_2O_4 nanoparticles were prepared through the rheological phase reaction method (R-ZMO) or the mixed solvothermal method (M-ZMO). • The M-ZMO behaved higher reversible capacity and better cycle performance than that of R-ZMO. • The morphology and cell parameters of ZnMn_2O_4 are important effects on its electrochemical properties. • The diffusion coefficient of Li"+ in M-ZMO is beneficial for M-ZMO to be used an anode. - Abstract: The precursors of ZnMn_2O_4 were synthesized by different methods (the rheological phase reaction method or the mixed solvothermal method). The precursors were heat-treated at a suitable temperature to obtain the expected product (ZnMn_2O_4). The synthesized samples were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The electrochemical properties of the samples were also investigated. The results show that ZnMn_2O_4 was synthesized successfully. The particles of ZnMn_2O_4 were irregular quasi-spheres with sizes of about 50 nm. The ZnMn_2O_4 nanoparticles synthesized through the mixed solvothermal method were clustered together to form microspheres about 1 μm in diameter. The electrochemical testing results showed that the ZnMn_2O_4 synthesized through the mixed solvothermal method featured higher reversible capacity and better cycling performance than the sample synthesized by the rheological phase reaction method. The ZnMn_2O_4 synthesized through the mixed solvothermal method could be a promising anode material for lithium ion battery application.

  9. Synthesis and electrochemical performance of hierarchical Sb2S3 nanorod-bundles for lithium-ion batteries

    Directory of Open Access Journals (Sweden)

    XIAOZHONG ZHOU

    2014-05-01

    Full Text Available Uniform hierarchical Sb2S3 nanorod-bundles were synthesised successfully by L-cysteine hydrochloride-assisted solvothermal treatment, and were then characterised by X-ray diffraction, field emission scanning electron microscopy, and high-resolution transmission electron microscopy, respectively. The electrochemical performance of the synthesised Sb2S3 nanorod-bundles was investigated by cyclic voltammetry and galvanostatic charge−discharge technique, respectively. This material was found to exhibit a high initial charge specific capacity of 803 mA h g-1 at a rate of 100 mA g-1, a good cyclability of 614 mA h g-1 at a rate of 100 mA g-1 after 30 cycles, and a good rate capability of 400 mA h g-1 at a rate of 500 mA g-1 when evaluated as an electrode candidate material for lithium-ion batteries.

  10. Synthesis, Characterizations and Investigation of Electrochemical Behaviours of 4-[(2-Hydroxyphenyliminomethyl]benzene-1,3-diol

    Directory of Open Access Journals (Sweden)

    Aysen D. Mulazimoglu

    2009-01-01

    Full Text Available This Schiff base ligand, 4-[(2-hydroxyphenylimino methyl]benzene-1,3-diol (HIBD was synthesized by reaction of 2-aminophenol and 2,4-dihydroxybenzaldehyde. The ligand was characterized by elemental analysis, FT-IR and 1H-NMR. Electrochemical behaviors were investigated on the glassy carbon electrode (GC surface with cyclic voltammetry (CV. The modification of HIBD on the GC was performed in +0.3 V and +2,8 V potential range using 100 mV s-1 scanning rate having 5 cycle. For the characterization of the modified surfaces 1 mM ferrocene redox probe in 0,1 M tetrabutylammonium tetrafluoroborate (TBATFB and 1 mM ferricyanide redox probe in 0.1 M H2SO4 were used.

  11. 3D nitrogen-doped graphene aerogel nanomesh: Facile synthesis and electrochemical properties as the electrode materials for supercapacitors

    Science.gov (United States)

    Su, Xiao-Li; Fu, Lin; Cheng, Ming-Yu; Yang, Jing-He; Guan, Xin-Xin; Zheng, Xiu-Cheng

    2017-12-01

    Nitrogen-doped graphene aerogel nanomesh (N-GANM) has been hydrothermally prepared from graphene oxide and ammonium hydroxide using iron nitrate as the etching agent. The results showed that N-GANM with an interesting nanomesh structure on the graphene sheets maintained the 3D architecture of graphene aerogel (GA). Furthermore, it exhibited excellent electrochemical capacitive behavior and the specific capacitance value (290.0 F g-1 at 1 A g-1) remained approximately 90.3% after 2000 cycles in the three-electrode system. In addition, N-GANM displayed an energy density of 30.9 Wh kg-1 at the power density of 450.3 W kg-1 and excellent cycling stability retention (98%) after 10,000 cycles in the two-electrode symmetric device. The resulting N-GANM was expected to be a much favorable supercapacitor electrode material due to the heteroatom-doping and its unique porous structure.

  12. Synthesis and electrochemical performances of amorphous carbon-coated Sn Sb particles as anode material for lithium-ion batteries

    Science.gov (United States)

    Wang, Zhong; Tian, Wenhuai; Liu, Xiaohe; Yang, Rong; Li, Xingguo

    2007-12-01

    The amorphous carbon coating on the Sn-Sb particles was prepared from aqueous glucose solutions using a hydrothermal method. Because the outer layer carbon of composite materials is loose cotton-like and porous-like, it can accommodate the expansion and contraction of active materials to maintain the stability of the structure, and hinder effectively the aggregation of nano-sized alloy particles. The as-prepared composite materials show much improved electrochemical performances as anode materials for lithium-ion batteries compared with Sn-Sb alloy and carbon alone. This amorphous carbon-coated Sn-Sb particle is extremely promising anode materials for lithium secondary batteries and has a high potentiality in the future use.

  13. Fabrication, Modification, and Emerging Applications of TiO2 Nanotube Arrays by Electrochemical Synthesis: A Review

    Directory of Open Access Journals (Sweden)

    Jian-Ying Huang

    2013-01-01

    Full Text Available Titania nanotube arrays (TNAs as a hot nanomaterial have a unique highly ordered array structure and good mechanical and chemical stability, as well as excellent anticorrosion, biocompatible, and photocatalytic performance. It has been fabricated by a facile electrochemical anodization in electrolytes containing small amounts of fluoric ions. In combination with our research work, we review the recent progress of the new research achievements of TNAs on the preparation processes, forming mechanism, and modification. In addition, we will review the potential and significant applications in the photocatalytic degradation of pollutants, solar cells, water splitting, and other aspects. Finally, the existing problems and further prospects of this renascent and rapidly developing field are also briefly addressed and discussed.

  14. Synthesis and electrochemical study of iron, chromium and tungsten aminocarbenes: Role of ligand structure and central metal nature

    Energy Technology Data Exchange (ETDEWEB)

    Hoskovcova, Irena [Department of Inorganic Chemistry, Institute of Chemical Technology, Technicka 5, 166 28 Prague 6 (Czech Republic); Rohacova, Jana; Dvorak, Dalimil; Tobrman, Tomas [Department of Organic Chemistry, Institute of Chemical Technology, Technicka 5, 166 28 Prague 6 (Czech Republic); Zalis, Stanislav [J. Heyrovsky Institute of Physical Chemistry, Academy of Science of the Czech Republic, Dolejskova 3, 182 23 Prague 8 (Czech Republic); Zverinova, Radka [Department of Inorganic Chemistry, Institute of Chemical Technology, Technicka 5, 166 28 Prague 6 (Czech Republic); J. Heyrovsky Institute of Physical Chemistry, Academy of Science of the Czech Republic, Dolejskova 3, 182 23 Prague 8 (Czech Republic); Ludvik, Jiri, E-mail: jiri.ludvik@jh-inst.cas.c [J. Heyrovsky Institute of Physical Chemistry, Academy of Science of the Czech Republic, Dolejskova 3, 182 23 Prague 8 (Czech Republic)

    2010-11-30

    Several series of Fischer-type aminocarbene complexes with central Fe, Cr or W atoms and with various carbene substitution were synthesized and electrochemically investigated by dc-polarography and cyclic voltammetry. The shifts and changes of reduction and oxidation potentials were evaluated using the linear free energy relationship (LFER) approach with respect to (a) the type of coordination, (b) the substitution on the carbene ligand and (c) the nature of the central metal atom. The analysis of measured data confirms that the reduction center is localized on the carbene moiety and is strongly influenced by both electronic and sterical properties of its substituents. The oxidation proceeds on the metal and depends mainly on its nature and on the {pi}-acidity of the ligands. Electrochemistry thus represents an important experimental approach to the description and understanding of the molecular electronic structure and redox properties. Experimental results are supported by DFT calculation of HOMO and LUMO orbitals shape and composition.

  15. Facile and Eco-Friendly Synthesis of Finger-Like Co3O4 Nanorods for Electrochemical Energy Storage

    Science.gov (United States)

    Sun, Shijiao; Zhao, Xiangyu; Yang, Meng; Ma, Liqun; Shen, Xiaodong

    2015-01-01

    Co3O4 nanorods were prepared by a facile hydrothermal method. Eco-friendly deionized water rather than organic solvent was used as the hydrothermal media. The as-prepared Co3O4 nanorods are composed of many nanoparticles of 30–50 nm in diameter, forming a finger-like morphology. The Co3O4 electrode shows a specific capacitance of 265 F g−1 at 2 mV s−1 in a supercapacitor and delivers an initial specific discharge capacity as high as 1171 mAh g−1 at a current density of 50 mA g−1 in a lithium ion battery. Excellent cycling stability and electrochemical reversibility of the Co3O4 electrode were also obtained. PMID:28347124

  16. Pt-Fe catalyst nanoparticles supported on single-wall carbon nanotubes: Direct synthesis and electrochemical performance for methanol oxidation

    Science.gov (United States)

    Ma, Xiaohui; Luo, Liqiang; Zhu, Limei; Yu, Liming; Sheng, Leimei; An, Kang; Ando, Yoshinori; Zhao, Xinluo

    2013-11-01

    Single-wall carbon nanotubes (SWCNTs) supported Pt-Fe nanoparticles have been prepared by one-step hydrogen arc discharge evaporation of carbon electrode containing both Pt and Fe metal elements. The formation of SWCNTs and Pt-Fe nanoparticles occur simultaneously during the evaporation process. High-temperature hydrogen treatment and hydrochloric acid soaking have been carried out to purify and activate those materials in order to obtain a new type of Pt-Fe/SWCNTs catalyst for methanol oxidation. The Pt-Fe/SWCNTs catalyst performs much higher electrocatalytic activity for methanol oxidation, better stability and better durability than a commercial Pt/C catalyst according to the electrochemical measurements, indicating that it has a great potential for applications in direct methanol fuel cells.

  17. Facile synthesis of Fe-incorporated CuO nanoarrays with enhanced electrochemical performance for lithium ion full batteries

    Energy Technology Data Exchange (ETDEWEB)

    Heng, Bojun [Institute of Nano-science and Technology, Central-China Normal University, Wuhan, 430079 (China); Department of Applied Physics, Wuhan University of Science and Technology, Wuhan, 430065 (China); Qing, Chen; Wang, Hai; Sun, Daming; Wang, Bixiao [Institute of Nano-science and Technology, Central-China Normal University, Wuhan, 430079 (China); Tang, Yiwen, E-mail: ywtang@phy.ccnu.edu.cn [Institute of Nano-science and Technology, Central-China Normal University, Wuhan, 430079 (China)

    2015-11-15

    CuO nanoarrays (CNAs) and Fe-incorporated CuO nanoarrays (FCNAs) were fabricated by hydrothermal method. Addition of Fe salt to the reaction mixture allowed the introduction of iron oxide onto the CNAs surface, which was characterized by XPS and HRTEM. Introducing Fe ion into reaction precursor significantly affected not only the morphologies of as-prepared products but also their electrochemical performance as anode for lithium ion full battery. The FCNAs electrodes showed higher specific capacity and better capacity retention at different current densities than that of CNAs. - Highlights: • Fe-incorporated CuO nanoarrays were fabricated by hydrothermal method. • Fe salt in reaction mixture leads to iron oxides forming on the surface of CuO. • Fe-incorporating improves the lithium ion battery performance of CuO anodes.

  18. CVD synthesis of carbon nanotubes using a finely dispersed cobalt catalyst and their use in double layer electrochemical capacitors

    International Nuclear Information System (INIS)

    Chatterjee, A.K.; Sharon, Maheshwar; Banerjee, Rangan; Neumann-Spallart, Michael

    2003-01-01

    Carbon nanotubes (CNT) were obtained by chemical vapour deposition (CVD), decomposing turpentine oil over finely dispersed Co metal as a catalyst at 675 deg. C. Scanning electron microscope (SEM) and transmission electron microscope (TEM) images reveal that the nanotubes are densely packed and of 10-50 nm in diameter. The XRD pattern of purified CNT shows that they are graphitic in nature. Resistivity measurements of these CNT indicate that they are highly conducting. Hall measurements of CNT reveal that electrons are the majority carriers with a carrier concentration of 1.35x10 20 cm -3 . Cyclic voltammetry (CV) and constant current charging/discharging was used to characterise the behaviour of electrochemical double layer capacitors of purified CNT with H 2 SO 4 . For CNT/2 M H 2 SO 4 /CNT, a capacitance of 12 F g -1 (based on the weight of the active material) was obtained

  19. Synthesis, photophysical and electrochemical characterization of terpyridine-functionalized dendritic oligothiophenes and their Ru(II complexes

    Directory of Open Access Journals (Sweden)

    Amaresh Mishra

    2013-05-01

    Full Text Available Pd-catalyzed Sonogashira cross-coupling reactions were used to synthesize novel π-conjugated oligothienylene-ethynylene dendrons and their corresponding terpyridine-based ligands. Their complexation with Ru(II led to interesting novel metallodendrimers with rich spectroscopic properties. All new compounds were fully characterized by 1H and 13C NMR, as well as MALDI–TOF mass spectra. Density functional theory (DFT calculations performed on these complexes gave more insight into the molecular orbital distributions. Photophysical and electrochemical studies were carried out in order to elucidate structure–property relationships and the effect of the dendritic structure on the metal complexes. Photophysical studies of the complexes revealed broad absorption spectra covering from 250 to 600 nm and high molar extinction coefficients. The MLCT emission of these complexes were significantly red-shifted (up to 115 nm compared to the parent [Ru(tpy2]2+ complex.

  20. Facile and Eco-Friendly Synthesis of Finger-Like Co3O4 Nanorods for Electrochemical Energy Storage

    Directory of Open Access Journals (Sweden)

    Shijiao Sun

    2015-12-01

    Full Text Available Co3O4 nanorods were prepared by a facile hydrothermal method. Eco-friendly deionized water rather than organic solvent was used as the hydrothermal media. The as-prepared Co3O4 nanorods are composed of many nanoparticles of 30–50 nm in diameter, forming a finger-like morphology. The Co3O4 electrode shows a specific capacitance of 265 F g−1 at 2 mV s−1 in a supercapacitor and delivers an initial specific discharge capacity as high as 1171 mAh g−1 at a current density of 50 mA g−1 in a lithium ion battery. Excellent cycling stability and electrochemical reversibility of the Co3O4 electrode were also obtained.

  1. Controllable synthesis, morphology evolution and electrochemical properties of LiFePO4 cathode materials for Li-ion batteries.

    Science.gov (United States)

    Song, Jianjun; Wang, Lin; Shao, Guangjie; Shi, Meiwu; Ma, Zhipeng; Wang, Guiling; Song, Wei; Liu, Shuang; Wang, Caixia

    2014-05-07

    Monodispersed LiFePO4 nanocrystals with diverse morphologies were successfully synthesized via a mild and controllable solvothermal approach with a mixture of ethylene glycol and oleic acid as the solvent. Morphology evolution of LiFePO4 nanoparticles from nanoplates to nanorods can be simply realized by varying the volume ratio of oleic acid to ethylene glycol. Moreover, the mechanism of competitive adsorption between ethylene glycol and oleic acid was proposed for the formation of different morphologies. Electrochemical measurements show that the LiFePO4/C nanorods have an initial discharge capacity of 155 mA h g(-1) at 0.5 C with a capacity retention of 80% at a high rate of 5 C, which confirms that LiFePO4/C nanorods exhibit excellent rate capability and cycling stability.

  2. Synthesis and electrochemical and in situ spectroelectrochemical characterization of manganese, vanadyl, and cobalt phthalocyanines with 2-naphthoxy substituents

    International Nuclear Information System (INIS)

    Ozcesmeci, Ibrahim; Koca, Atif; Guel, Ahmet

    2011-01-01

    Highlights: → Metallo (Mn, Co, VO) phthalocyanines bearing peripheral 2-naphthoxy-groups were synthesized by cyclotetramerisation of the corresponding phthalonitrile derivative. → Incorporation of the redox active metal ions into the phthalocyanine core extends the redox capabilities of the Pc ring. → The presence of O 2 in the electrolyte system influences both oxygen reduction reaction and the electrochemical and spectral behaviors of the complexes. → Homogeneous catalytic ORR process occurs via an 'inner sphere' chemical catalysis process. - Abstract: Metallo (Mn, Co, VO) phthalocyanines bearing peripheral 2-naphthoxy groups were synthesized by cyclotetramerisation of the corresponding phthalonitrile derivative. The phthalocyanine compounds were characterized by elemental analyses, mass, FT-IR and UV-vis spectral data. Three intense bands in the electronic spectra clearly indicate the absorptions resulting from naphthyl groups along with the Q and B bands of the phthalocyanines. Electrochemical and spectroelectrochemical measurements exhibit that incorporation of redox active metal ions, Co II and Mn III , into the phthalocyanine core extends the redox capabilities of the Pc ring including the metal-based reduction and oxidation couples of the metal. Presence of molecular oxygen in the electrolyte system affects the voltammetric and spectroelectrochemical responses of the cobalt and manganese phthalocyanines due to the interaction between the complexes and molecular oxygen. Interaction reaction of oxygen with CoPc occurs via an 'inner sphere' chemical catalysis process. While CoPc gives the intermediates [O 2 - -Co II Pc -2 ] - and [O 2 2 -Co II Pc -2 ] 2- , MnPc forms μ-oxo MnPc species. An in situ electrocolorimetric method has been applied to investigate the color of the electro-generated anionic and cationic forms of the complexes for possible electrochromatic applications.

  3. Synthesis and electrochemical capacitive properties of nitrogen-doped porous carbon micropolyhedra by direct carbonization of zeolitic imidazolate framework-11

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Fei; Li, Li; Zhang, Xiaohua, E-mail: mickyxie@hnu.edu.cn; Chen, Jinhua, E-mail: chenjinhua@hnu.edu.cn

    2015-06-15

    Highlights: • Nitrogen-doped porous carbon micropolyhedra (N-PCMPs) were prepared from ZIF-11. • The activated N-PCMPs with fused KOH (N-PCMPs-A) have high specific surface area. • N-PCMPs-A exhibits high specific capacitance. • N-PCMPs-A reveals good cycling performance even at a high current density. - Abstract: Nitrogen-doped porous carbon micropolyhedra (N-PCMPs) were successfully prepared by direct carbonization of ZIF-11 polyhedra and further activated with fused KOH to obtain N-PCMPs-A. The morphology and microstructure of samples were examined by scanning electron microscopy, X-ray diffraction, and micropore and chemisorption analyzer. Electrochemical properties were characterized by cyclic voltammetry and galvanostatic charge/discharge method in 1.0 M H{sub 2}SO{sub 4} aqueous solution on a standard three-electrode system. Results show that, compared with N-PCMPs, N-PCMPs-A has higher specific surface area (2188 m{sup 2} g{sup −1}) and exhibits improved electrochemical capacitive properties (307 F g{sup −1} at 1.0 A g{sup −1}). The mass specific capacitance of N-PCMPs-A is also higher than that of most MOF-derived carbons, some carbide-derived carbons and carbon aerogel-derived carbons. In addition, the capacitance of the N-PCMPs-A retains 90% after 4000 cycles even at a high current density of 10 A g{sup −1}. These imply that N-PCMPs-A is the promising materials for the construction of a high-performance supercapacitor.

  4. One-pot hydrothermal synthesis, characterization, and electrochemical properties of rGO/MnFe2O4 nanocomposites

    Science.gov (United States)

    Kotutha, Isara; Swatsitang, Ekaphan; Meewassana, Worawat; Maensiri, Santi

    2015-06-01

    In this work, a simple facile route for preparing an rGO/MnFe2O4 nanocomposite through a one-pot hydrothermal approach was demonstrated. Graphite oxide (GO) was prepared from graphite powder by a modified Hummers method. Fe(NO3)2 • 9H2O and Mn(NO3)2 • H2O were used as the precursors for the preparation of the rGO/MnFe2O4 nanocomposite. The formation of the rGO/MnFe2O4 nanocomposite was confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and Rama spectroscopy (Raman). The specific surface area of the prepared composite obtained by Brunauer-Emmett-Teller (BET) analysis was lower than that of pure rGO but higher than that of pure MnFe2O4. Consequently, the electrochemical performance was investigated by using a three-electrode cell system in 6.0 M KOH. The results show that the specific capacitance was determined to be 190.3, 276.9, and 144.5 F/g at a scan rate of 10 mV/s, and 194.9, 274.6, and 134.4 F/g at a current density of 5.0 A/g for rGO, rGO/(5 mmol) MnFe2O4, and rGO/(10 mmol) MnFe2O4, respectively. These results suggest that the composite of MnFe2O4 nanoparticles on an rGO nanosheet can improve the capacitive behavior of the fabricated electrode, but the electrochemical properties are reduced when the MnFe2O4 concentration ratio is high.

  5. Synthesis, structure, magnetic, electrical and electrochemical properties of Al, Cu and Mg doped MnO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Hashem, Ahmed M., E-mail: ahmedh242@yahoo.com [National Research Centre, Inorganic Chemistry Department, Behoes St., Dokki, Cairo (Egypt); Institute for Complex Materials, IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Abuzeid, Hanaa M. [National Research Centre, Inorganic Chemistry Department, Behoes St., Dokki, Cairo (Egypt); Narayanan, N. [Institute for Complex Materials, IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Ehrenberg, Helmut [Institute for Complex Materials, IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Materials Science, Technische Universitaet Darmstadt, Petersenstr. 23, D-64287 Darmstadt (Germany); Julien, C.M. [Universite Pierre et Marie Curie, Physicochimie des Electrolytes, Colloides et Sciences Analytiques (PECSA), 4 place Jussieu, 75005 Paris (France)

    2011-10-17

    Highlights: {yields} Al, Mg and Cu doped MnO{sub 2} as cathode in Li-ion batteries. {yields} Pure phase MnO{sub 2} for virgin and doped MnO{sub 2} were obtained. {yields} Doping elements improve the electrical conductivity of MnO{sub 2}. {yields} Electrochemical behaviour of MnO{sub 2} improved after doping by Al, Mg and Cu. - Abstract: Pure and doped manganese dioxides were prepared by wet-chemical method using fumaric acid and potassium permanganate as raw materials. X-ray diffraction patterns show that pure and Al, Cu and Mg doped manganese dioxides (d-MnO{sub 2}) crystallized in the cryptomelane-MnO{sub 2} structure. Thermal analysis show that, with the assistance of potassium ions inside the 2 x 2 tunnel, the presence of Al, Cu and Mg doping elements increases the thermal stability of d-MnO{sub 2}. The electrical conductivity of d-MnO{sub 2} increases in comparison with pure MnO{sub 2}, while Al-doped MnO{sub 2} exhibits the lower resistivity. As shown in the magnetic measurements, the value of the experimental effective magnetic moment of Mn ions decreases with introduction of dopants, which is attributed to the presence of a mixed valency of high-spin state Mn{sup 4+}/Mn{sup 3+}. Doped MnO{sub 2} materials show good capacity retention in comparison with virgin MnO{sub 2}. Al-doped MnO{sub 2} shows the best electrochemical results in terms of capacity retention and recharge efficiency.

  6. Cobalt and Vanadium Trimetaphosphate Polyanions: Synthesis, Characterization, and Electrochemical Evaluation for Non-aqueous Redox-Flow Battery Applications.

    Science.gov (United States)

    Stauber, Julia M; Zhang, Shiyu; Gvozdik, Nataliya; Jiang, Yanfeng; Avena, Laura; Stevenson, Keith J; Cummins, Christopher C

    2018-01-17

    An electrochemical cell consisting of cobalt ([Co II/III (P 3 O 9 ) 2 ] 4-/3- ) and vanadium ([V III/II (P 3 O 9 ) 2 ] 3-/4- ) bistrimetaphosphate complexes as catholyte and anolyte species, respectively, was constructed with a cell voltage of 2.4 V and Coulombic efficiencies >90% for up to 100 total cycles. The [Co(P 3 O 9 ) 2 ] 4- (1) and [V(P 3 O 9 ) 2 ] 3- (2) complexes have favorable properties for flow-battery applications, including reversible redox chemistry, high stability toward electrochemical cycling, and high solubility in MeCN (1.09 ± 0.02 M, [PPN] 4 [1]·2MeCN; 0.77 ± 0.06 M, [PPN] 3 [2]·DME). The [PPN] 4 [1]·2MeCN and [PPN] 3 [2]·DME salts were isolated as crystalline solids in 82 and 68% yields, respectively, and characterized by 31 P NMR, UV/vis, ESI-MS(-), and IR spectroscopy. The [PPN] 4 [1]·2MeCN salt was also structurally characterized, crystallizing in the monoclinic P2 1 /c space group. Treatment of 1 with [(p-BrC 6 H 4 ) 3 N] + allowed for isolation of the one-electron-oxidized spin-crossover (SCO) complex, [Co(P 3 O 9 ) 2 ] 3- (3), which is the active catholyte species generated during cell charging. The success of the 1-2 cell provides a promising entry point to a potential future class of transition-metal metaphosphate-based all-inorganic non-aqueous redox-flow battery electrolytes.

  7. Synthesis of nitrogen-doped activated graphene aerogel/gold nanoparticles and its application for electrochemical detection of hydroquinone and o-dihydroxybenzene

    Science.gov (United States)

    Juanjuan, Zhang; Ruiyi, Li; Zaijun, Li; Junkang, Liu; Zhiguo, Gu; Guangli, Wang

    2014-04-01

    Graphene aerogel materials have attracted increasing attention owing to their large specific surface area, high conductivity and electronic interactions. Here, we report for the first time a novel strategy for the synthesis of nitrogen-doped activated graphene aerogel/gold nanoparticles (N-doped AGA/GNs). First, the mixture of graphite oxide, 2,4,6-trihydroxybenzaldehyde, urea and potassium hydroxide was dispersed in water and subsequently heated to form a graphene oxide hydrogel. Then, the hydrogel was dried by freeze-drying and reduced by thermal annealing in an Ar/H2 environment in sequence. Finally, GNs were adsorbed on the surface of the N-doped AGA. The resulting N-doped AGA/GNs offers excellent electronic conductivity (2.8 × 103 S m-1), specific surface area (1258 m2 g-1), well-defined 3D hierarchical porous structure and apparent heterogeneous electron transfer rate constant (40.78 +/- 0.15 cm s-1), which are notably better than that of previous graphene aerogel materials. Moreover, the N-doped AGA/GNs was used as a new sensing material for the electrochemical detection of hydroquinone (HQ) and o-dihydroxybenzene (DHB). Owing to the greatly enhanced electron transfer and mass transport, the sensor displays ultrasensitive electrochemical response to HQ and DHB. Its differential pulse voltammetric peak current linearly increases with the increase of HQ and DHB in the range of 5.0 × 10-8 to 1.8 × 10-4 M for HQ and 1 × 10-8 to 2.0 × 10-4 M for DHB. The detection limit is 1.5 × 10-8 M for HQ and 3.3 × 10-9 M for DHB (S/N = 3). This method provides the advantage of sensitivity, repeatability and stability compared with other HQ and DHB sensors. The sensor has been successfully applied to detection of HQ and DHB in real water samples with the spiked recovery in the range of 96.8-103.2%. The study also provides a promising approach for the fabrication of various graphene aerogel materials with improved electrochemical performances, which can be potentially

  8. One-pot hydrothermal synthesis of zirconium dioxide nanoparticles decorated reduced graphene oxide composite as high performance electrochemical sensing and biosensing platform

    International Nuclear Information System (INIS)

    Teymourian, Hazhir; Salimi, Abdollah; Firoozi, Somayeh; Korani, Aazam; Soltanian, Saied

    2014-01-01

    Graphical abstract: - Highlights: • One pot hydrothermal synthesis used for preparing of ZrO 2 NPs reduced graphene oxide. • Electrocatalytic activity of ZrO 2 /rGO improved in compared to ZrO 2 based C- materials. • ZrO 2 NPs/rGO modified GCE was used for electrocatalytic reduction of O 2 and H 2 O 2 . • ZrO 2 NPs/rGO/GCE shows excellent ability to simultaneous detection of AA,UA and DP. • With immobilization of GOX onto ZrO 2 NPs/rGO a sensitive glucose biosensor fabricated. - Abstract: We report on the synthesis of zirconium dioxide-reduced graphene oxide composite (ZrO 2 -rGO) and its application as a novel architecture for electrochemical sensing and biosensing purposes. ZrO 2 -rGO hybrid is synthesized through a simple one-step hydrothermal route, where the reduction of GO and the in-situ generation of ZrO 2 nanoparticles (NPs) occurred simultaneously. Characterization of the resultant hybrid material using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectroscopy clearly indicated the homogeneous dispersion of ZrO 2 NPs with particle sizes of ∼5 nm on rGO sheets. The potential application of ZrO 2 -rGO modified glassy carbon electrode (ZrO 2 -rGO/GC) for electroanalytical purposes was demonstrated by using several important electroactive compounds as representative examples (i.e., O 2 , hydrogen peroxide (H 2 O 2 ), glucose, ascorbic acid (AA), dopamine (DA) and uric acid (UA)). Electrochemical control experiments by using different composites of ZrO 2 /graphite, ZrO 2 /Active Carbon and ZrO 2 electrodeposited on activated GC electrode revealed that the ZrO 2 -rGO composite possessed superior electrocatalytic activitiy towards the catalytic reduction of O 2 and H 2 O 2 at more reduced overpotentials. The linear range of H 2 O 2 concentration was from 0.10 to 1340 μM with the detection limit of 20 nM (S/N = 3). Furthermore, via immobilization of glucose oxidase (GOx) enzyme onto the

  9. Large-scale synthesis of ultrathin Au-Pt nanowires assembled on thionine/graphene with high conductivity and sensitivity for electrochemical immunosensor

    International Nuclear Information System (INIS)

    Lu, Wenbo; Ge, Juan; Tao, Lin; Cao, Xiaowei; Dong, Jian; Qian, Weiping

    2014-01-01

    In this article, for the first time, a novel, label-free and inherent electroactive redox biosensor based on ultrathin Au-Pt nanowire-decorated thionine/reduced graphene oxide (AuPtNWs/THI/rGO) is developed for carcinoembryonic antigen (CEA) detection. Ultrathin AuPtNWs are prepared by a one-pot synthesis method without the use of any stabilizer or template. The AuPtNWs/THI/rGO composites are obtained by the THI/rGO composites surface functionalized with -NH 2 group employed as a support for loading ultrathin AuPtNWs by coordination. The AuPtNWs/THI/rGO composites not only favor the immobilization of antibody but also facilitate the electron transfer. It is found that the resultant AuPtNWs/THI/rGO composites can be designed to act as a sensitive label-free electrochemical immunosensor for CEA determination. Under the optimized conditions, the linear range of the proposed immunosensor is estimated to be from 50 fg·mL −1 to 100 ng·mL −1 (R= 0.998) and the detection limit is estimated to be 6 fg·mL −1 at a signal-to-noise ratio of 3, respectively. The prepared immunosensor for detection of CEA shows high sensitivity, reproducibility and stability. Our study demonstrates that the proposed immunosensor has also been used to determine CEA successfully in diluted blood samples

  10. Graphene quantum dots decorated with magnetic nanoparticles: Synthesis, electrodeposition, characterization and application as an electrochemical sensor towards determination of some amino acids at physiological pH

    International Nuclear Information System (INIS)

    Hasanzadeh, Mohammad; Karimzadeh, Ayub; Shadjou, Nasrin; Mokhtarzadeh, Ahad; Bageri, Leyla; Sadeghi, Sattar; Mahboob, Soltanali

    2016-01-01

    This study reports on the synthesis and characterization of a novel nano-composite, Fe 3 O 4 magnetic nanoparticles/graphene quantum dots (Fe 3 O 4 MNP-GQDs), for sensing of some amino acids. For the first time, as-synthesized GQDs and Fe 3 O 4 MNPs-GQDs was electrodeposited on the glassy carbon electrode (GCE) by cyclic voltammetry (CV) regime in the potential range from − 1.0 to 1.0 V. Fe 3 O 4 MNP-GQDs is engineered to specifically and effectively capture and enhancement the electrochemical signals of some amino acids at physiological pH due to the synergy among GQDs and magnetic nanoparticles. We have illustrated that the obtained Fe 3 O 4 MNPs-GQDs exhibited a much higher electroactivity individual GQDs and Fe 3 O 4 MNPs for the electrooxidation and detection of amino acid which was about 10 fold higher than for GQDs. Magnetic and specific properties of the Fe 3 O 4 MNP-GQDs can be exploited to capture and pre-concentration the amino acids onto its surface, which are important for detection of multi-amino acids. - Highlights: • Electrooxidation of amino acids was performed using Fe 3 O 4 MNP-GQDs. • Modified electrode shows new advantages as an amino acids sensor. • Excellent electrocatalytic activity was obtained for amino acids oxidation.

  11. Synthesis and characterization of the WxRuySez from the electrochemical reduction of oxygen and their possible application as electrode in fuel cell

    International Nuclear Information System (INIS)

    Ramirez R, S.D.

    1995-01-01

    In this communication the synthesis of the W 0.03 RuSe 0.47 O 0.3 from the transition metal carbonyl compounds and the chalcogenide in m Xylene, the chemical characterization of the novel material was performed by neutron activation analysis (NAA), using the TRIGA Mark III Reactor from the Nuclear Center of Mexico. The oxygen present in the material was determined by Rutherford Backscattering Spectrometry (RBS). Also the RuSe 5.7 y WSe 2 were synthesized and characterized by NAA. The electro kinetic oxygen reduction behaviour of the W 0.03 RuSe 0.47 O 0.3 deposited in glassy carbon was investigated in aqueous H 2 SO 4 0.5M. The rotating disk electrode electrochemical technique was used for determining the kinetic parameters: The reaction was of first order which implied that the rate determining step is the transfer of one electron, the Tafel slope was 0.115 V/decade; the electron transfer coefficient found was of 0.5, and the activation energy in the oxygen reduction reaction was 0.47 eV. (Author)

  12. Electrochemical synthesis of SnCo alloy shells on orderly rod-shaped Cu current collectors as anode materials for lithium-ion batteries with enhanced performance

    Energy Technology Data Exchange (ETDEWEB)

    Zhan, Fangwei; Zhang, Hui, E-mail: meszhanghui@zju.edu.cn; Qi, Yue; Wang, Jiazheng; Du, Ning; Yang, Deren

    2013-09-05

    Highlights: •Nanostructured SnCo/Cu electrodes have been successfully fabricated. •A simple electrodeposition approach was employed. •The Cu arrays offer large surface area and improve electronic/ionic conductivity. •The electrodes show improved performance as anode for Li-ion batteries. •The improved performance was attributed to the nanostructured current collectors. -- Abstract: In this article, we report a two-step electrodeposition method for the synthesis of Cu/SnCo core–shell rod-shaped arrays as anodes of lithium-ion batteries. Firstly, the arrayed Cu nanorods with diameters of 200 nm were fabricated on a Cu foil through an electrodeposition method with alumina oxide membrane (AAO) as the template. Secondly, the SnCo alloy shells were subsequently electrodeposited on the surface of the rod-shaped Cu arrays to form the hybrid nanostructures. These hybrid electrodes delivered the enhanced cyclic performance and high rate capability serving as the anode materials for lithium-ion batteries. The improved electrochemical performance might be attributed to the large surface-to-volume area, sufficient buffering space, and high electronic conductivity associated with these 3-dimensional (3D) nanostructures.

  13. Synthesis of iron oxides nanoparticles with very high saturation magnetization form TEA-Fe(III) complex via electrochemical deposition for supercapacitor applications

    Science.gov (United States)

    Elrouby, Mahmoud; Abdel-Mawgoud, A. M.; El-Rahman, Rehab Abd

    2017-11-01

    This work is devoted to the synthesis of magnetic iron oxides nanoparticles with very high saturation magnetization to be qualified for supercapacitor applications using, a simple electrodeposition technique. It is found that the electrochemical reduction process depends on concentration, temperature, deposition potential and the scan rate of potential. The nature of electrodeposition process has been characterized via voltammetric and chronoamperometric techniques. The morphology of the electrodeposits has been investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The structure and phase content of these investigated electrodeposits have been examined and calculated. The obtained iron oxides show a high saturation magnetization (Ms) of about 229 emu g-1. The data exhibited a relation between Ms of electrodeposited iron oxide and specific capacitance. This relation exhibits that the highest Ms value of electrodeposited iron oxides gives also highest specific capacitance of about 725 Fg-1. Moreover, the electrodeposited iron oxides exhibit a very good stability. The new characteristics of the electro synthesized iron oxides at our optimized conditions, strongly qualify them as a valuable material for high-performance supercapacitor applications.

  14. TCNQ-induced in-situ electrochemical deposition for the synthesis of silver nanodendrites as efficient bifunctional electrocatalysts

    International Nuclear Information System (INIS)

    Chen, Zhengyan; Li, Congling; Ni, Yangyang; Kong, Fantao; Zhang, Yongbo; Kong, Aiguo; Shan, Yongkui

    2017-01-01

    Graphical abstract: Silver nanodendrites with superior electrocatalytic activity for oxygen reduction reaction (ORR) and hydrogen peroxide detection were synthesized by electrodeposition method using organic semiconductor 7,7,8,8-tetracyanoquinodimethane (TCNQ) as the inducer. - Highlights: • AgNDs were obtained by electrodepositing route under the induction of TCNQ. • The AgNDs-TCNQ/GCE showed superior activity comparable to Pt/C for ORR. • The AgNDs-TCNQ/GCE exhibited highly catalytic activity toward H_2O_2 detection. • A novel pathway for synthesizing bifunctional Ag-based electrocatalyst. - Abstract: Sliver (Ag) nanodendrites (AgNDs) directly growing on the glassy carbon electrode (GCE) were obtained by an in-situ electrodepositing route under the induction of organic semiconductor 7,7,8,8-tetracyanoquinodimethane (TCNQ). The morphology of the Ag nanostructures can be controlled by the electrodepositing time, applied potentials, and the concentrations of Ag ions. The AgNDs/TCNQ/GCE obtained at the optimized conditions displays the oxygen reduction reaction (ORR) onset potential of 0.98 V, which is the same as that over Pt/C-JM catalyst (0.98 V). It demonstrated that AgNDs possessed the highest electrocatalytic activity for ORR among the various Ag-based electrocatalysts reported in literature in alkaline electrolyte. At the same time, the performance of AgNDs/TCNQ/GCE toward hydrogen peroxide detection was investigated in a range of the concentration from 10 μM to 17 mM. It also showed the higher catalytic activity for hydrogen peroxide reduction reaction with the hydrogen peroxide detection limit reaching 0.47 μM level. The Tafel polarization curve, electrochemically active surface area, and the electrochemical impedance were measured to understand and explore the catalytic behavior of the prepared AgNDs/TCNQ/GCE. The enhanced performance of AgNDs for ORR and hydrogen peroxide detection can be ascribed to the special tree-like morphology with highly

  15. Synthesis and electrochemical properties of high performance polyhedron sphere like lithium manganese oxide for lithium ion batteries

    International Nuclear Information System (INIS)

    Guo, Donglei; Wei, Xiuge; Chang, Zhaorong; Tang, Hongwei; Li, Bao; Shangguan, Enbo; Chang, Kun; Yuan, Xiao-Zi; Wang, Haijiang

    2015-01-01

    Graphical abstract: Polyhedron structured sphere-like LiMn 2 O 4 synthesized from β-MnO 2 nanorod precursor via a solid state reaction at a temperature of 800 °C exhibits excellent rate capability and cycling performance at both 25 °C and 55 °C. - Highlights: • Polyhedron sphere-like LiMn 2 O 4 was synthesized from β-MnO 2 nanorod precursor. • The polyhedron sphere-like LiMn 2 O 4 exhibits excellent rate capability and cycling performance. • The polyhedron sphere-like structure spinel LiMn 2 O 4 suppresses the dissolution of manganese ions. • The polyhedron sphere-like LiMn 2 O 4 has high diffusion coefficient of Li + . - Abstract: Polyhedron structured sphere-like lithium manganese oxide (LiMn 2 O 4 ) is successfully synthesized from β-MnO 2 nanorod precursor via a solid state reaction at a temperature of 800 °C. For comparison, LiMn 2 O 4 materials with nanorod and octahedron structures are also obtained from β-MnO 2 nanorod precursor at temperatures of 700 °C and 900 °C, respectively. The galvanostatic charge–discharge result shows that the polyhedron sphere-like LiMn 2 O 4 sample exhibits the best electrochemical performance at high rate and high temperature. After 100 cycles at 5 C, this electrode is able to maintain 94% of its capacity at 25 °C and 81% at 55 °C. This is attributed to that the polyhedron sphere-like spinel LiMn 2 O 4 can suppress the dissolution of manganese ions. Based on Brunauer Emmett Teller (BET), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), the polyhedron sphere-like LiMn 2 O 4 sample has the lowest BET surface area, largest diffusion coefficient of Li + and least charge transfer resistance. This study provides an insight into the capacity fading of LiMn 2 O 4 electrodes and the polyhedron structured sphere-like LiMn 2 O 4 can be a promising material for lithium ion batteries

  16. A New All-Solid-State Hyperbranched Star Polymer Electrolyte for Lithium Ion Batteries: Synthesis and Electrochemical Properties

    International Nuclear Information System (INIS)

    Wang, Ailian; Xu, Hao; Zhou, Qian; Liu, Xu; Li, Zhengyao; Gao, Rui; Wu, Na; Guo, Yuguo; Li, Huayi; Zhang, Liaoyun

    2016-01-01

    Highlights: • A new hyperbranched multi-arm star polymer was successfully synthesized. • The star polymer electrolyte has good thermal stability and forming-film property. • The ion conductivity electrolyte can reach 8.3 × 10"−"5 S cm"−"1 at room temperature. • The star polymer electrolyte has wide electrochemical windows of 4.7 V. - Abstract: A new hyperbranched multi-arm star polymer with hyperbranched polystyrene (HBPS) as core and polymethyl methacrylate-block-poly(ethylene glycol) methyl ether methacrylate(PMMA-b-PPEGMA) as arms was firstly synthesized by atom transfer radical polymerization. The obtained hyperbranched multi-arm star polymer (HBPS-(PMMA-b-PPEGMA)_x) exhibited good thermal stability with a thermal decomposition temperature of 372 °C. The transparent, free-standing, flexible polymer electrolyte film of the blending of HBPS-(PMMA-b-PPEGMA)_x and lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) was successfully fabricated by a solution casting method. The ionic conductivity of the hyperbranched star polymer electrolyte with a molar ratio of [EO]/[Li] of 30 could reach 8.3 × 10"−"5 S cm"−"1 at 30 °C (with the content of PPEGMA of 83.7%), and 2.0 × 10"−"4 S cm"−"1 at 80 °C (with the content of PPEGMA of 51.6%). The effect of the concentration of lithium salts on ionic conductivity was also investigated. The obtained all-solid-state polymer electrolyte possessed a wide electrochemical stability window of 4.7 V (vs. Li"+/Li), and a lithium-ion transference number (t_L_i"+) up to 0.31. The interfacial impedance of the fabricated LiÔöépolymer electrolyteÔöéLi symmetric cell based on hyperbranched star multi-arm polymer electrolyte exhibited good interfacial compatibility between all-solid-state polymer electrolyte and electrodes. The excellent properties of the hyperbranched star polymer electrolyte made it attractive as solid-state polymer electrolyte for lithium-ion batteries.

  17. Controllable Electrochemical Synthesis of Copper Sulfides as Sodium-Ion Battery Anodes with Superior Rate Capability and Ultralong Cycle Life.

    Science.gov (United States)

    Li, Haomiao; Wang, Kangli; Cheng, Shijie; Jiang, Kai

    2018-03-07

    Sodium-ion batteries (SIBs) are prospective alternative to lithium-ion batteries for large-scale energy-storage applications, owing to the abundant resources of sodium. Metal sulfides are deemed to be promising anode materials for SIBs due to their low-cost and eco-friendliness. Herein, for the first time, series of copper sulfides (Cu 2 S, Cu 7 S 4 , and Cu 7 KS 4 ) are controllably synthesized via a facile electrochemical route in KCl-NaCl-Na 2 S molten salts. The as-prepared Cu 2 S with micron-sized flakes structure is first investigated as anode of SIBs, which delivers a capacity of 430 mAh g -1 with a high initial Coulombic efficiency of 84.9% at a current density of 100 mA g -1 . Moreover, the Cu 2 S anode demonstrates superior capability (337 mAh g -1 at 20 A g -1 , corresponding to 50 C) and ultralong cycle performance (88.2% of capacity retention after 5000 cycles at 5 A g -1 , corresponding to 0.0024% of fade rate per cycle). Meanwhile, the pseudocapacitance contribution and robust porous structure in situ formed during cycling endow the Cu 2 S anodes with outstanding rate capability and enhanced cyclic performance, which are revealed by kinetics analysis and ex situ characterization.

  18. One-step hydrothermal synthesis of graphene decorated V2O5 nanobelts for enhanced electrochemical energy storage.

    Science.gov (United States)

    Lee, Minoh; Balasingam, Suresh Kannan; Jeong, Hu Young; Hong, Won G; Lee, Han-Bo-Ram; Kim, Byung Hoon; Jun, Yongseok

    2015-01-30

    Graphene-decorated V2O5 nanobelts (GVNBs) were synthesized via a low-temperature hydrothermal method in a single step. V2O5 nanobelts (VNBs) were formed in the presence of graphene oxide, a mild oxidant, which also enhanced the conductivity of GVNBs. From the electron energy loss spectroscopy analysis, the reduced graphene oxide (rGO) are inserted into the layered crystal structure of V2O5 nanobelts, which further confirmed the enhanced conductivity of the nanobelts. The electrochemical energy-storage capacity of GVNBs was investigated for supercapacitor applications. The specific capacitance of GVNBs was evaluated using cyclic voltammetry (CV) and charge/discharge (CD) studies. The GVNBs having V2O5-rich composite, namely, V3G1 (VO/GO = 3:1), showed superior specific capacitance in comparison to the other composites (V1G1 and V1G3) and the pure materials. Moreover, the V3G1 composite showed excellent cyclic stability and the capacitance retention of about 82% was observed even after 5000 cycles.

  19. Hydrothermal synthesis and electrochemical properties of nano-sized Co-Sn alloy anodes for lithium ion batteries

    International Nuclear Information System (INIS)

    He Jianchao; Zhao Hailei; Wang Jing; Wang Jie; Chen Jingbo

    2010-01-01

    Research highlights: → Nano-sized Co-Sn alloys were synthesized by hydrothermal route. → Li 2 O and CoSn can buffer the large volume change associated with lithiation of Sn. → A two-step reaction mechanism of CoSn 2 alloy during cycling was confirmed. - Abstract: Nano-sized Co-Sn alloys with a certain amount of Sn oxides used as potential anode materials for lithium ion batteries were synthesized by hydrothermal route. The effects of hydrothermal conditions and post annealing on the phase compositions and the electrochemical properties of synthesized powders were characterized by means of X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) with energy dispersive spectra (EDS) analysis and galvanostatic cycling tests. Prolonging the dwelling time at the same hydrothermal temperature can increase the content of Sn oxides, which will lead to a high initial irreversible capacity loss but a better cycling stability owing to the buffer effect of irreversible product Li 2 O. Heat-treatment can increase the crystallinity and cause the presence of a certain amount of inert CoSn component, which both have positive impact on the cycling stability of Co-Sn electrode. By comparison with the lithiation/delithiation processes of metal Sn, a two-step mechanism of CoSn 2 alloy during cycling was confirmed.

  20. One-pot synthesis of NiO/Mn2O3 nanoflake arrays and their application in electrochemical biosensing

    Science.gov (United States)

    Wang, Yao; Cui, Jiewu; Luo, Lan; Zhang, Jingcheng; Wang, Yan; Qin, Yongqiang; Zhang, Yong; Shu, Xia; Lv, Jun; Wu, Yucheng

    2017-11-01

    The exploration of novel nanomaterials employed as substrate to construct glucose biosensors is still of significance in the field of clinical diagnosis. In this work, NiO/Mn2O3 nanoflake arrays were synthesized by hydrothermal approach in combination with calcination process. As-prepared NiO/Mn2O3 nanoflake arrays were utilized to construct electrochemical biosensors for glucose detection. NiO/Mn2O3 nanoflake arrays were investigated systematically by scanning electron microscopy (SEM), X-ray diffractionmeter (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy, the formation mechanism of NiO/Mn2O3 nanoflake arrays was proposed. As-prepared glucose biosensors based on NiO/Mn2O3 nanoflake arrays were characterized by cyclic voltammgrams and chronoamperometry. The results indicated that glucose biosensors based on optimized NiO/Mn2O3 nanoflake arrays exhibited a high sensitivity of 167.0 μA mM-1 Cm-2 and good anti-interference ability, suggesting the NiO/Mn2O3 nanoflake arrays are an attractive substrate for the construction of oxidase-based biosensors.

  1. Electrochemical synthesis of p-Cu_2O/n-ZnO nanorods hetero-junction for photovoltaic application

    International Nuclear Information System (INIS)

    Rokade, A. V.; Rondiya, S. R.; Jadhavar, A. A.; Pandharkar, S. M.; Karpe, S. D.; Diwate, K. D.; Jadkar, S. R.

    2016-01-01

    Development of high performance visible light responsive solar cell materials has attracted wide interest due to their potential applications in the energy industries. In this work, ZnO nanorods films were successfully prepared on the ITO coated glass substrates via simple three electrode electrochemical deposition route. The Cu_2O nanoparticles were then electrodeposited on the surface of ZnO nanorods to form p-Cu_2O/n-ZnO core-shell hetero-structure. The synthesized ZnO, Cu_2O films and p-Cu_2O/n-ZnO hetero-structure were characterized by low angle x-ray diffraction, scanning electron microscopy, and UV-Visible spectrophotometer. Due to the hierarchical morphologies and core-shell structure, p-Cu_2O/n-ZnO hetero-structure shows a prominent visible-light-driven photocatalytic performance under the low intensity light irradiation. The obtained results suggest that it is possible to synthesize ZnO nanorods, Cu_2O films and p-Cu_2O/n-ZnO core-shell hetero-structure by a simple, cost effective and environment friendly electrodeposition process which can be useful for water splitting and solar cell device fabrication.

  2. Electrochemical synthesis of nickel hexacyanoferrate nanoarrays with dots, rods and nanotubes morphology using a porous alumina template

    Energy Technology Data Exchange (ETDEWEB)

    Sabzi, Reza Emamali [Department of Chemistry, Faculty of Science, Urmia University, Urmia (Iran, Islamic Republic of); Kant, Krishna [University of South Australia, Ian Wark Research Institute, Mawson Lakes Campus, Mawson Lakes, Adelaide, SA 5095 (Australia); Losic, Dusan, E-mail: dusan.losic@unisa.edu.a [University of South Australia, Ian Wark Research Institute, Mawson Lakes Campus, Mawson Lakes, Adelaide, SA 5095 (Australia)

    2010-02-01

    Transition metal hexacyanoferrate (MeHCF) have attracted extensive attention because of their outstanding properties including, electrocatalysis, molecular magnetism, biosensing and ion-exchange. This paper describes an approach for fabrication of ordered nanoarrays of Ni hexacyanoferrate (NiHCF) structures with different morphologies such as dots, rods and tubes in order to advance their properties and applications. The method is based on the conversion of Ni into NiHCF nanostructures by electrochemical oxidation in the presence of hexacyanoferrate ions, using nanoporous anodic alumina oxide (AAO) as a template. The structure and morphology of formed Ni and NiHCF nanoarrays were confirmed by scanning electron microscopy (SEM), showing agreement with the pore structures of the AAO template. The electrocatalytic activity of NiHCF nanorod array electrodes showed high catalytic properties for the detection of hydrogen peroxide and the potential to be used as a platform for direct biosensing applications. The ion-exchange ability of fabricated NiHCF nanostructures (nanorods and nanotubes) toward alkali cations such as Na{sup +} has been successfully confirmed.

  3. Electrochemical synthesis of nickel hexacyanoferrate nanoarrays with dots, rods and nanotubes morphology using a porous alumina template

    International Nuclear Information System (INIS)

    Sabzi, Reza Emamali; Kant, Krishna; Losic, Dusan

    2010-01-01

    Transition metal hexacyanoferrate (MeHCF) have attracted extensive attention because of their outstanding properties including, electrocatalysis, molecular magnetism, biosensing and ion-exchange. This paper describes an approach for fabrication of ordered nanoarrays of Ni hexacyanoferrate (NiHCF) structures with different morphologies such as dots, rods and tubes in order to advance their properties and applications. The method is based on the conversion of Ni into NiHCF nanostructures by electrochemical oxidation in the presence of hexacyanoferrate ions, using nanoporous anodic alumina oxide (AAO) as a template. The structure and morphology of formed Ni and NiHCF nanoarrays were confirmed by scanning electron microscopy (SEM), showing agreement with the pore structures of the AAO template. The electrocatalytic activity of NiHCF nanorod array electrodes showed high catalytic properties for the detection of hydrogen peroxide and the potential to be used as a platform for direct biosensing applications. The ion-exchange ability of fabricated NiHCF nanostructures (nanorods and nanotubes) toward alkali cations such as Na + has been successfully confirmed.

  4. Electrochemical synthesis of bilayer coatings of poly(N-methylaniline) and polypyrrole on mild steel and their corrosion protection performances

    Energy Technology Data Exchange (ETDEWEB)

    Zeybek, Buelent [Ankara University, Faculty of Science, Department of Chemistry, Ankara (Turkey); Dumlupinar University, Faculty of Arts and Sciences, Department of Chemistry, Kuetahya (Turkey); Ozcicek Pekmez, Nuran, E-mail: npekmez@hacettepe.edu.t [Hacettepe University, Faculty of Science, Department of Chemistry, Ankara (Turkey); Kilic, Esma [Ankara University, Faculty of Science, Department of Chemistry, Ankara (Turkey)

    2011-10-30

    Highlights: > The bilayers of poly(N-methylaniline) and polypyrrole-dodecylsulfate were synthesized. > These films on mild steel were characterized by cyclic voltammetry, FTIR and FESEM. > DS dopant allows permeation to cations and decreases the ingress of chloride ions. > The PNMA/PPy-DS bilayer coating exhibited the best corrosion resistance in 0.5 M HCl. > The protective properties of polymers was developed by preparing their bilayer coatings. - Abstract: Homopolymer and bilayer coatings of poly(N-methylaniline) (PNMA) and polypyrrole-dodecylsulfate (PPy-DS) have been electropolymerized on a mild steel (MS) surface by the potentiodynamic method in aqueous oxalic acid solutions. In order to include dodecylsulfate ion as dopant in the polypyrrole, sodium dodecylsulfate was also added to the polymerization solution of pyrrole. Characterization of coatings was carried out by the cyclic voltammetry, Fourier transform infrared (FTIR) spectroscopy and field emission scanning electron microscopy (FESEM). Corrosion behavior of the polymer coated MS electrodes was investigated in highly aggressive 0.5 M HCl solution by the Tafel test and electrochemical impedance spectroscopy (EIS) techniques. Corrosion test revealed that among the protective coatings obtained, the PNMA/PPy-DS bilayer exhibited the best corrosion resistance at all immersion times.

  5. Synthesis, Crystal Structure, Luminescence, Electrochemical and Antimicrobial Properties of Bis(salamo-Based Co(II Complex

    Directory of Open Access Journals (Sweden)

    Li Wang

    2017-09-01

    Full Text Available A newly designed Co(II complex, [Co3(L(OAc2(CH3OH2]·CH3OH, by the reaction of a bis(salamo-type tetraoxime ligand (H4L with Co(II acetate tetrahydrate was synthesized and characterized by elemental analyses, IR, UV-vis spectra and single-crystal X-ray crystallography. The UV-vis titration experiment manifested that a trinuclear (L:M = 1:3 complex was formed. It is worth noting that the two terminal Co(II (Co1 and Co3 atoms of the Co(II complex have different coordination modes and geometries unreported earlier. Furthermore, through intermolecular interactions (C–H···O, C–H···π and O–H···O, a 2D layer-like network is constructed. In addition, the fluorescence behaviors, antimicrobial activities and electrochemical properties of H4L and its Co(II complex were investigated.

  6. Synthesis, Optical and Electrochemical Properties of Y2O3 Nanoparticles Prepared by Co-Precipitation Method.

    Science.gov (United States)

    Saravanan, Thulasingam; Raj, Srinivasan Gokul; Chandar, Nagamuthu Raja Krishna; Jayavel, Ramasamy

    2015-06-01

    Y2O3 nanoparticles were synthesized by co-precipitation route using yttrium nitrate hexahydrate and ammonium hydroxide as precursors. The prepared sample was calcined at 500 degrees C and subjected to various characterization studies like thermal analysis (TG/DTA), X-ray diffraction (XRD), transmission electron microscope (TEM), UV-visible (UV-Vis) and photoluminescence (PL) spectroscopy. The XRD pattern showed the cubic fluorite structure of Y2O3 without any impurity peaks, revealing high purity of the prepared sample. TEM images revealed that the calcined Y2O3 nanoparticles consist of spherical-like morphology with an average particle size of 12 nm. The absorption spectrum of calcined samples shows blue-shift compared to the as-prepared sample, which was further confirmed by PL studies. The possible formation mechanism of Y2O3 nanoparticles has been discussed based on the experimental results. Electrochemical behavior of Y2O3 nanoparticles was studied by cyclic voltammetry to assess their suitability for supercapacitor applications.

  7. One-pot synthesis of powder-form {beta}-Ni(OH){sub 2} monolayer nanosheets with high electrochemical performance

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Minmin; Ren, Wanzhong; Zhao, Yunan; Liu, Yan; Cui, Hongtao, E-mail: htcui@ytu.edu.cn [Yantai University, Shandong Provincial Engineering Research Center for Light Hydrocarbon Comprehensive Utilization, College of Chemistry and Chemical Engineering (China)

    2013-08-15

    In this work, {beta}-Ni(OH){sub 2} monolayer nanosheets, which had been thought to be unachievable, were successfully prepared for the first time by a one-pot strategy using epoxide as precipitation agent and sodium dodecyl sulfate (SDS) as surfactant. The characterization results indicate that the formation of monolayer morphology depends on the mediation of SDS molecules. The XRD patterns demonstrate the loose and defective packing of Ni(OH){sub 2} layers in the SDS intercalated samples. The disappearing of vibration band of free hydroxyl groups in the FTIR spectra suggests the interlayer separation resulted by SDS. The TEM and AFM images further confirm the formation of monolayer nanosheets. It is proposed that the in situ modification of the secondary growth unit of {beta}-Ni(OH){sub 2} by SDS allows its two-dimensional anisotropic growth through steric hindrance of SDS molecules. In addition, this effect allows isolation of {beta}-Ni(OH){sub 2} from solvent with keeping of monolayer nanosheet state in dry powder. The electrochemical measurement results indicate that {beta}-Ni(OH){sub 2} monolayer nanosheets own much higher urea electrolysis performance than their corresponding multilayer structure.

  8. One-pot synthesis of powder-form β-Ni(OH)2 monolayer nanosheets with high electrochemical performance

    International Nuclear Information System (INIS)

    Wang, Minmin; Ren, Wanzhong; Zhao, Yunan; Liu, Yan; Cui, Hongtao

    2013-01-01

    In this work, β-Ni(OH) 2 monolayer nanosheets, which had been thought to be unachievable, were successfully prepared for the first time by a one-pot strategy using epoxide as precipitation agent and sodium dodecyl sulfate (SDS) as surfactant. The characterization results indicate that the formation of monolayer morphology depends on the mediation of SDS molecules. The XRD patterns demonstrate the loose and defective packing of Ni(OH) 2 layers in the SDS intercalated samples. The disappearing of vibration band of free hydroxyl groups in the FTIR spectra suggests the interlayer separation resulted by SDS. The TEM and AFM images further confirm the formation of monolayer nanosheets. It is proposed that the in situ modification of the secondary growth unit of β-Ni(OH) 2 by SDS allows its two-dimensional anisotropic growth through steric hindrance of SDS molecules. In addition, this effect allows isolation of β-Ni(OH) 2 from solvent with keeping of monolayer nanosheet state in dry powder. The electrochemical measurement results indicate that β-Ni(OH) 2 monolayer nanosheets own much higher urea electrolysis performance than their corresponding multilayer structure

  9. Spontaneous Synthesis and Electrochemical Characterization of Nanostructured MnO2 on Nitrogen-Incorporated Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Ying-Chu Chen

    2012-01-01

    Full Text Available This paper investigated the layered manganese dioxide with hydrate (MnO2⋅xH2O deposits onto nitrogen-containing carbon nanotube (CNxNTs as a hierarchical electrode for an energy-storage device. The dense and entangled CNxNTs were directly grown by microwave plasma-enhanced chemical vapor deposition (MPECVD on a carbon cloth (CC, and subsequently used as a current collector. By controlling the pH value of KMnO4 precursor solution, and incorporating nitrogen into CNTs as a reducing agent, the MnO2 thin layer was uniformly fabricated on the CNxNTs at room temperature by using a spontaneous reduction method. The role of incorporation nitrogen is not only capable of creating active sites on the CNT surface, but can also donate electrons to reduce MnO4- to MnO2 spontaneously. From the measurements of cyclic voltammograms and galvanostatic charge/discharge, MnO2/CNxNTs/CC composite electrodes illustrated excellent specific capacitance of 589.1 Fg-1. The key factor for high performance could be attributed to the thin-layered MnO2 nanostructure, which resulted in the full utilization of MnO2 deposits. Hence, the hierarchically porous MnO2/CNxNTs/CC electrodes exhibited excellent capacitive behavior for electrochemical capacitor application.

  10. Magnetic field-assisted synthesis of wire-like Co3O4 nanostructures: Electrochemical and photocatalytic studies

    International Nuclear Information System (INIS)

    Zhao, Xiubin; Pang, Zhanwen; Wu, Mingzai; Liu, Xiansong; Zhang, Hui; Ma, Yongqing; Sun, Zhaoqi; Zhang, Lide; Chen, Xiaoshuang

    2013-01-01

    Graphical abstract: Schematic illustration for the magnetic field-assisted growth of wire-like Co 3 O 4 nanostructure. Display Omitted Highlights: ► Co 3 O 4 nanowires are prepared by magnetic field hydrothermal reduction and annealing. ► These Co 3 O 4 nanowires possess enhanced capacitance. ► The Co 3 O 4 nanowires have a good photocatalytic activity for methyl orange. -- Abstract: Wire-like Co 3 O 4 nanostructures were prepared by the combination of magnetic field-assisted hydrothermal reduction of cobalt ions and the subsequent ambient annealing at 500 °C. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the structure and morphological evolution of the products. The results show that the wire-like nanostructures possess diameters about 250 nm and lengths over 10 μm. The possible formation mechanism of the wire-like Co 3 O 4 nanostructures is also proposed based on the SEM results. Galvanostatic methods were used to characterize the electrochemical properties. The measurements indicate that the wire-like Co 3 O 4 nanostructures show larger discharge and charge capacities than that of spherical Co 3 O 4 nanoparticles prepared in the absence of magnetic field. In addition, the photocatalytic activity of the products was investigated by measuring the photodegradation of methyl orange solution under ultraviolet radiation, which shows that both the wire-like and spherical products have a good photocatalytic activity.

  11. Controllable synthesis and enhanced electrochemical properties of multifunctional Au(core)Co(3)O(4shell) nanocubes.

    Science.gov (United States)

    Hu, Jianqiang; Wen, Zhenhai; Wang, Qiang; Yao, Xin; Zhang, Qian; Zhou, Jianhua; Li, Jinghong

    2006-12-07

    Multifunctional Au(core)Co(3)O(4shell) nanocubes were synthesized through the introduction of chloroauric acid (HAuCl(4)) into a typical hydrothermal system after a solvothermal process was completed to form metastable Co(3)O(4) hollow nanospheres in the presence of sodium dodecyl benzenesulfonate (SDBS), which served as the surfactant. The strategy suggested that HAuCl(4) played a vital role in the shape transformation and core/shell structure formation, and the sizes of the nanocubes can be tunable through control of the acid concentration. The core/shell structure of the nanocubes was demonstrated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and element analysis (EA) measurements. Moreover, Li ion battery measurement indicated that trace Au intercalation altered not only the size and shape of the Co(3)O(4) nanoparticles but also greatly increased their electrochemical properties. These multifunctional nanocubes will be not only helpful to study physical chemistry properties of magnetic nanocrystals but also are expected to find use in many fields such as biomolecular detection and analysis, sensor, electrochemistry, and Li ion batteries.

  12. Facile synthesis and electrochemical performances of hollow graphene spheres as anode material for lithium-ion batteries

    Science.gov (United States)

    Yao, Ran-Ran; Zhao, Dong-Lin; Bai, Li-Zhong; Yao, Ning-Na; Xu, Li

    2014-07-01

    The hollow graphene oxide spheres have been successfully fabricated from graphene oxide nanosheets utilizing a water-in-oil emulsion technique, which were prepared from natural flake graphite by oxidation and ultrasonic treatment. The hollow graphene oxide spheres were reduced to hollow graphene spheres at 500°C for 3 h under an atmosphere of Ar(95%)/H2(5%). The first reversible specific capacity of the hollow graphene spheres was as high as 903 mAh g-1 at a current density of 50 mAh g-1. Even at a high current density of 500 mAh g-1, the reversible specific capacity remained at 502 mAh g-1. After 60 cycles, the reversible capacity was still kept at 652 mAh g-1 at the current density of 50 mAh g-1. These results indicate that the prepared hollow graphene spheres possess excellent electrochemical performances for lithium storage. The high rate performance of hollow graphene spheres thanks to the hollow structure, thin and porous shells consisting of graphene sheets.

  13. Hydrothermal synthesis, characterization, formation mechanism and electrochemical property of V3O7.H2O single-crystal nanobelts

    International Nuclear Information System (INIS)

    Zhang Yifu; Liu Xinghai; Xie Guangyong; Yu Lei; Yi Shengping; Hu Mingjie; Huang Chi

    2010-01-01

    Single-crystal V 3 O 7 .H 2 O nanobelts have been successfully synthesized in a large-scale by ethanol reducing of the commercial V 2 O 5 powder via a facile hydrothermal approach, without any templates and surfactants. The as-prepared V 3 O 7 .H 2 O nanobelts are up to several tens of micrometers in length, about 100 nm in width and about 20 nm in thickness in average, respectively. The 'Hydrating-Reducing-Exfoliating-Splitting' (HRES) mechanism was proposed to describe the formation of the V 3 O 7 .H 2 O nanobelts. In our research progress, it was found that the ratio of EtOH/H 2 O, the reaction time and categories of the reducing agents had significant effects on the morphology and composition of as-obtained products. Furthermore, the electrochemical properties of V 3 O 7 .H 2 O nanobelts were preformed and the results revealed that a lithium battery using those nanobelts as the positive electrode exhibited a high initial discharge capacity of 373 mAh/g.

  14. Synthesis and electrochemical properties of Li4Ti5O12 spheres and its application for hybrid supercapacitors

    International Nuclear Information System (INIS)

    Deng, SiXu; Li, JingWen; Sun, ShiBing; Wang, Hao; Liu, JingBing; Yan, Hui

    2014-01-01

    Highlights: • Li 4 Ti 5 O 12 (LTO) spheres are prepared by molten-salt and TiO 2 spheres as template. • The LTO spheres are potential for using as anode for AC//LTO hybrid capacitor. • The AC//LTO hybrid supercapacitor presents good electrochemical performance. - Abstract: There is a growing demand for hybrid supercapacitor systems to combine the advantages of both lithium-ion battery and supercapacitors for the application of electric vehicles. We describe in this paper one kind of hybrid supercapacitor comprising spherical Li 4 Ti 5 O 12 as negative electrode and activated carbon (AC) as positive electrode in the non-aqueous electrolyte. The Li 4 Ti 5 O 12 spheres were synthesized using a LiCl-KCl molten-salt method and TiO 2 spheres as the template. The Li 4 Ti 5 O 12 spheres revealed high discharge capacity (168 mAh g −1 at 0.2 C), and a good capacity retention with high coulombic efficiency after cycling, which can be potential anode material for lithium ion batteries and negative material for hybrid supercapacitor. The AC//LTO hybrid supercapacitor exhibits excellent capacity retention of 93% after 500 cycles and offers higher energy density and power density than the AC//AC symmetric supercapacitor. The presented AC//LTO hybrid supercapacitor could be a competitive candidate for the promising energy storage devices

  15. Controllable synthesis of hollow bipyramid β-MnO(2) and its high electrochemical performance for lithium storage.

    Science.gov (United States)

    Chen, Wei-Min; Qie, Long; Shao, Qing-Guo; Yuan, Li-Xia; Zhang, Wu-Xing; Huang, Yun-Hui

    2012-06-27

    Three types of MnO2 nanostructures, viz., α-MnO2 nanotubes, hollow β-MnO2 bipyramids, and solid β-MnO2 bipyramids, have been synthesized via a simple template-free hydrothermal method. Cyclic voltammetry and galvanostatic charge/discharge measurements demonstrate that the hollow β-MnO2 bipyramids exhibit the highest specific capacity and the best cyclability; the capacity retains 213 mAh g(-1) at a current density of 100 mA g(-1) after 150 cycles. XRD patterns of the lithiated β-MnO2 electrodes clearly show the expansion of lattice volume caused by lithiation, but the structure keeps stable during lithium insertion/extraction process. We suggest that the excellent performance for β-MnO2 can be attributed to its unique electrochemical reaction, compact tunnel-structure and hollow architecture. The hollow architecture can accommodate the volume change during charge/discharge process and improve effective diffusion paths for both lithium ions and electrons.

  16. Novel homo- and heterobinuclear ball-type phthalocyanines: synthesis and electrochemical, electrical, EPR and MCD spectral properties.

    Science.gov (United States)

    Odabaş, Zafer; Dumludağ, Fatih; Ozkaya, Ali Riza; Yamauchi, Seigo; Kobayashi, Nagao; Bekaroğlu, Ozer

    2010-09-21

    The mononuclear Fe(II) phthalocyanine 2 and ball-type homobinuclear Fe(II)-Fe(II) and Cu(II)-Cu(II) phthalocyanines, 3 and 4 respectively, were synthesized from the corresponding 4,4'-[1,1'-methylenebis-(naphthalene-2,1-diyl)]bis(oxy)diphthalonitrile 1, and then ball-type heterobinuclear Fe(II)-Cu(II) phthalocyanine 5 was synthesized from 2. The novel compounds 4 and 5 have been characterized by elemental analysis, UV/vis, IR and MALDI-TOF mass spectroscopies. Electron paramagnetic resonance and magnetic circular dichroism measurements of 3, 4 and 5 were also examined. The voltammetric measurements of the complexes showed the formation of various electrochemically stable ligand- and metal-based mixed-valence species, due to the intramolecular interactions between the two MPc units, especially in ball-type binuclear iron(II) phthalocyanine. Impedance spectroscopy and d.c. conductivity measurements of 4 and 5 were performed as a function of temperature (295-523 K) and frequency (40-10(5) Hz). While room temperature impedance spectra consist of a curved line, a transformation into a full semicircle with increasing temperature was observed for both compounds.

  17. Lanthanide(III) complexes of bis-semicarbazone and bis-imine-substituted phenanthroline ligands: solid-state structures, photophysical properties, and anion sensing.

    Science.gov (United States)

    Nadella, Sandeep; Selvakumar, Paulraj M; Suresh, Eringathodi; Subramanian, Palani S; Albrecht, Markus; Giese, Michael; Fröhlich, Roland

    2012-12-21

    Phenanthroline-based hexadentate ligands L(1) and L(2) bearing two achiral semicarbazone or two chiral imine moieties as well as the respective mononuclear complexes incorporating various lanthanide ions, such as La(III), Eu(III), Tb(III), Lu(III), and Y(III) metal ions, were synthesized, and the crystal structures of [ML(1)Cl(3)] (M=La(III), Eu(III), Tb(III), Lu(III), or Y(III)) complexes were determined. Solvent or water molecules act as coligands for the rare-earth metals in addition to halide anions. The big Ln(III) ion exhibits a coordination number (CN) of 10, whereas the corresponding Eu(III), Tb(III), Lu(III), and Y(III) centers with smaller ionic radii show CN=9. Complexes of L(2), namely [ML(2)Cl(3)] (M=Eu(III), Tb(III), Lu(III), or Y(III)) ions could also be prepared. Only the complex of Eu(III) showed red luminescence, whereas all the others were nonluminescent. The emission properties of the Eu derivative can be applied as a photophysical signal for sensing various anions. The addition of phosphate anions leads to a unique change in the luminescence behavior. As a case study, the quenching behavior of adenosine-5'-triphosphate (ATP) was investigated at physiological pH value in an aqueous solvent. A specificity of the sensor for ATP relative to adenosine-5'-diphosphate (ADP) and adenosine-5'-monophosphate (AMP) was found. (31)P NMR spectroscopic studies revealed the formation of a [EuL(2)(ATP)] coordination species. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Synthesis and electrochemical performance of ruthenium oxide-coated carbon nanofibers as anode materials for lithium secondary batteries

    Energy Technology Data Exchange (ETDEWEB)

    Hyun, Yura; Choi, Jin-Yeong [Department of Chemistry, Keimyung University (Korea, Republic of); Park, Heai-Ku [Department of Chemical Engineering, Keimyung University (Korea, Republic of); Lee, Chang-Seop, E-mail: surfkm@kmu.ac.kr [Department of Chemistry, Keimyung University (Korea, Republic of)

    2016-12-01

    Highlights: • Ruthenium oxide (RuO{sub 2}) coated carbon nanofibers (CNFs) on Ni foam were synthesized by chemical vapor deposition method and applied as anode materials of Li secondary batteries. • When RuO{sub 2}/CNFs/Ni foam was used as the anode material, initial capacity was improved from 276 mAh/g to 494 mAh/g with retention rate of 47.4% after 30 cycles. - Abstract: In this study, ruthenium oxide (RuO{sub 2}) coated carbon nanofibers (CNFs) were synthesized and applied as anode materials of Li secondary batteries. The CNFs were grown on Ni foam via chemical vapor deposition (CVD) method after CNFs/Ni foam was put into the 0.01 M RuCl{sub 3} solution. The ruthenium oxide-coated CNFs/Ni foam was dried in a dryer at 80 °C. The morphologies, compositions, and crystal quality of RuO{sub 2}/CNFs/Ni foam were characterized by SEM, EDS, XRD, Raman spectroscopy, and XPS. The electrochemical characteristics of RuO{sub 2}/CNFs/Ni foam as anode of Li secondary batteries were investigated using three-electrode cell. The RuO{sub 2}/CNFs/Ni foam was directly employed as a working electrode without any binder, and lithium foil was used as the counter and reference electrodes. LiClO{sub 4} (1 M) was employed as electrolyte and dissolved in a mixture of propylene carbonate (PC): ethylene carbonate (EC) in a 1:1 volume ratio. The galvanostatic charge/discharge cycling and cyclic voltammetry measurements were carried out at room temperature by using a battery tester. In particular, synthesized RuO{sub 2}/CNFs/Ni foam showed the highest retention rate (47.4%). The initial capacity (494 mAh/g) was reduced to 234 mAh/g after 30 cycles.

  19. Synthesis and electrochemical performance of ruthenium oxide-coated carbon nanofibers as anode materials for lithium secondary batteries

    International Nuclear Information System (INIS)

    Hyun, Yura; Choi, Jin-Yeong; Park, Heai-Ku; Lee, Chang-Seop

    2016-01-01

    Highlights: • Ruthenium oxide (RuO_2) coated carbon nanofibers (CNFs) on Ni foam were synthesized by chemical vapor deposition method and applied as anode materials of Li secondary batteries. • When RuO_2/CNFs/Ni foam was used as the anode material, initial capacity was improved from 276 mAh/g to 494 mAh/g with retention rate of 47.4% after 30 cycles. - Abstract: In this study, ruthenium oxide (RuO_2) coated carbon nanofibers (CNFs) were synthesized and applied as anode materials of Li secondary batteries. The CNFs were grown on Ni foam via chemical vapor deposition (CVD) method after CNFs/Ni foam was put into the 0.01 M RuCl_3 solution. The ruthenium oxide-coated CNFs/Ni foam was dried in a dryer at 80 °C. The morphologies, compositions, and crystal quality of RuO_2/CNFs/Ni foam were characterized by SEM, EDS, XRD, Raman spectroscopy, and XPS. The electrochemical characteristics of RuO_2/CNFs/Ni foam as anode of Li secondary batteries were investigated using three-electrode cell. The RuO_2/CNFs/Ni foam was directly employed as a working electrode without any binder, and lithium foil was used as the counter and reference electrodes. LiClO_4 (1 M) was employed as electrolyte and dissolved in a mixture of propylene carbonate (PC): ethylene carbonate (EC) in a 1:1 volume ratio. The galvanostatic charge/discharge cycling and cyclic voltammetry measurements were carried out at room temperature by using a battery tester. In particular, synthesized RuO_2/CNFs/Ni foam showed the highest retention rate (47.4%). The initial capacity (494 mAh/g) was reduced to 234 mAh/g after 30 cycles.

  20. Synthesis and electrochemical sodium and lithium insertion properties of sodium titanium oxide with the tunnel type structure

    Science.gov (United States)

    Kataoka, Kunimitsu; Akimoto, Junji

    2016-02-01

    Polycrystalline sample of sodium titanium oxide Na2Ti4O9 with the tunnel-type structure was prepared by topotactic sodium extraction in air atmosphere from the as prepared Na3Ti4O9 sample. The starting Na3Ti4O9 compound was synthesized by solid state reaction at 1273 K in Ar atmosphere. The completeness of oxidation reaction from Na3Ti4O9 to Na2Ti4O9 was monitored by the change in color from dark blue to white, and was also confirmed by the Rietveld refinement using the powder X-ray diffraction data. The sodium deficient Na2Ti4O9 maintained the original Na2.08Ti4O9-type tunnel structure and had the monoclinic crystal system, space group C2/m, and the lattice parameters of a = 23.1698(3) Å, b = 2.9406(1) Å, c = 10.6038(2) Å, β = 102.422(3)°, and V = 705.57(2) Å3. The electrochemical measurements of thus obtained Na2Ti4O9 sample showed the reversible sodium insertion and extraction reactions at 1.1 V, 1.5 V, and 1.8 V vs. Na/Na+, and reversible lithium insertion and extraction reactions at around 1.4 V, 1.8 V, and 2.0 V vs. Li/Li+. The reversible capacity for the lithium cell was achieved to be 104 mAh g-1 at the 100th cycle.

  1. Electrochemical synthesis of multi-armed CuO nanoparticles and their remarkable bactericidal potential against waterborne bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, Pratibha, E-mail: rkpratibha@yahoo.com; Merwyn, S.; Agarwal, G. S.; Tripathi, B. K.; Pant, S. C. [Defence Research and Development Establishment (India)

    2012-01-15

    Copper (II) oxide multi-armed nanoparticles composed of 500-1000 nm long radiating nanospicules with 100-200 nm width near the base and 50-100 nm width at the tapered ends and {approx}25 nm thickness were synthesized by electrochemical deposition in the presence of an oxidant followed by calcination at 150 Degree-Sign C. The nanoparticles were characterized using SEM/EDX for morphology and composition, Raman spectroscopy for compound identification, and broth culture method for antibacterial efficacy. The CuO nanoparticles have shown remarkable bactericidal efficacy against Gram-positive and -negative waterborne disease causing bacteria like Escherichia coli, Salmonella typhi, staphylococcus aureus and Bacillus subtilis. E. coli has been chosen as representative species for waterborne disease causing bacteria. In antibacterial tests 500 {mu}g/mL nano CuO killed 3 Multiplication-Sign 10{sup 8} CFU/mL E. coli bacteria within 4 h of exposure. Moreover, 8.3 Multiplication-Sign 10{sup 6} CFU/mL E. coli were killed by 100 and 10 {mu}g/mL nano CuO within 15 min and 4 h of exposure, respectively. Antibacterial activity of nano CuO has been found many-fold compared with commercial bulk CuO. The fate of nanoparticles after antibacterial test has also been studied. The synthesized CuO nanoparticles are expected to have potential antibacterial applications in water purification and in paints and coatings used on frequently touched surfaces and fabrics in hospital settings.

  2. Synthesis, characterization and electrochemical studies of Pt- W/C catalyst for polymer electrolyte membrane fuel cells

    International Nuclear Information System (INIS)

    Ahmed, R.; Shahid, S.; Ansari, M. S.

    2013-01-01

    Pt-W/C catalyst was synthesized by slow reduction of platinum and tungsten solutions in the desired ratio with subsequent deposition on the Vulcan carbon already added to the solution. Crystallite size of catalyst was about 9 nm and its density, cell volume, d-spacing and lattice parameter were also calculated. EDX analysis of the catalyst was also done. Electrochemical surface area of the catalyst was determined by cyclic voltammetry (CV). CV of the catalyst was done both in acidic and basic media to find out the peak potential, peak current, specific activity and mass activity of the catalyst. Peak potential versus scan rate plots showed that the electro oxidation of methanol is an irreversible process. Tafel equation was used to plot polarization curves to find out the exchange current density. Higher values of exchange current indicate better catalysts. Specific activities of the catalyst were determined in acidic and basic media and it was found that the specific activity in basic media increased substantially as compared to acidic media. The specific activity in acidic media was 83 mA/mg pt whereas in basic media it was 137mA/mg pt which is a substantial increase. Heterogeneous rate constant in acidic media was 6.15 * 10-6 cm/ s and in basic media it was 4.92 * 10-5 cm/s which is much higher in basic media. In this binary catalyst addition of tungsten has increased the catalytic activity but it is non-noble metal thus will decrease the cost. Stability studies of the catalyst were done upto fifty cycles both in acidic and basic media and was found quite stable in both the media. (author)

  3. Synthesis, characterization and electrochemical studies of Pt-W/C catalyst for polymer electrolyte membrane fuel cells

    International Nuclear Information System (INIS)

    Ahmed, Riaz; Shahid, Saliha; Ansari, Muhammad Shahid

    2014-01-01

    Pt-W/C catalyst was synthesized by slow reduction of platinum and tungsten solutions in the desired ratio with subsequent deposition on the Vulcan carbon already added to the solution. Crystallite size of catalyst was about 9 nm and its density, cell volume, d-spacing and lattice parameter were also calculated. EDX analysis of the catalyst was also done. Electrochemical surface area of the catalyst was determined by cyclic voltammetry (CV). CV of the catalyst was done both in acidic and basic media to find out the peak potential, peak current, specific activity and mass activity of the catalyst. Peak potential versus scan rate plots showed that the electro oxidation of methanol is an irreversible process. Tafel equation was used to plot polarization curves to find out the exchange current density. Higher values of exchange current indicate better catalysts. Specific activities of the catalyst were determined in acidic and basic media and it was found that the specific activity in basic media increased substantially as compared to acidic media. The specific activity in acidic media was 83 mA/mg pt whereas in basic media it was 137mA/mg pt which is a substantial increase. Heterogeneous rate constant in acidic media was 6.15 x 10 −6 cm/ s and in basic media it was 4.92 x 10 −5 cm/s which is much higher in basic media. In this binary catalyst addition of tungsten has increased the catalytic activity but it is non-noble metal thus will decrease the cost. Stability studies of the catalyst were done upto fifty cycles both in acidic and basic media and was found quite stable in both the media

  4. Hydrothermal synthesis and electrochemical performance of Co3O4/reduced graphene oxide nanosheet composites for supercapacitors

    International Nuclear Information System (INIS)

    Song, Zhaoxia; Zhang, Yujuan; Liu, Wei; Zhang, Song; Liu, Guichang; Chen, Huiying; Qiu, Jieshan

    2013-01-01

    Highlights: • Co 3 O 4 /reduced graphene oxide sheet-on-sheet nanocomposites are synthesized. • Co 3 O 4 nanosheets consist of homogeneously assembled nanoparticles. • Co 3 O 4 /rGONS shows a specific capacitance of 402 F g −1 at 2.0 A g −1 . • Co 3 O 4 /rGONS shows enhanced capacitive performance compared with Co 3 O 4 . • The improved properties are mainly attributed to the porous composite structure. - Abstract: The composites of Co 3 O 4 /reduced graphene oxide nanosheets (Co 3 O 4 /rGONS) are prepared via a facile hydrothermal route followed by calcination, of which the morphology and microstructure are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It is found that the as-obtained Co 3 O 4 nanosheets on which many fine nanoparticles are homogeneously assembled aggregate in a flower shape on the surfaces of reduced graphene oxide. Electrochemical properties are investigated using cyclic voltammetry and galvanostatic charge/discharge in 1 M KOH aqueous solution. In comparison with pure Co 3 O 4 , the specific capacity and redox performance of the as-made Co 3 O 4 /rGONS composites have been significantly improved, which are mainly attributed to the composite structure with high porosity formed due to the interaction of Co 3 O 4 and reduced graphene oxide nanosheets during the fabrication process of the Co 3 O 4 /rGONS nanocomposites. The Co 3 O 4 /rGONS-II shows good cyclic performance and coulomb efficiency with a specific capacitance over 400 F g −1 at a current density of 0.5–2.0 A g −1

  5. Synthesis, photophysical and electrochemical properties, and protein-binding studies of luminescent cyclometalated iridium(III) bipyridine estradiol conjugates.

    Science.gov (United States)

    Lo, Kenneth Kam-Wing; Zhang, Kenneth Yin; Chung, Chi-Keung; Kwok, Karen Ying

    2007-01-01

    A new series of luminescent cyclometalated iridium(III) bipyridine estradiol conjugates [Ir(N-C)2(N-N)](PF6) (N-N = 5-(4-(17alpha-ethynylestradiolyl)phenyl)-2,2'-bipyridine, bpy-est, HN-C = 2-phenylpyridine, Hppy (1 a), 1-phenylpyrazole, Hppz (2 a), 7,8-benzoquinoline, Hbzq (3 a), 2-phenylquinoline, Hpq (4 a), 2-((1,1'-biphenyl)-4-yl)benzothiazole, Hbsb (5 a); N-N = 4-(N-(6-(4-(17alpha-ethynylestradiolyl)benzoylamino)hexyl)aminocarbonyl)-4'-methyl-2,2'-bipyridine, bpy-C6-est, HN-C = Hppy (1 b), Hppz (2 b), Hbzq (3 b), Hpq (4 b), Hbsb (5 b)) was synthesized, characterized, and their photophysical and electrochemical properties studied. Upon photoexcitation, all the complexes displayed intense and long-lived emission in fluid solutions at 298 K and in low-temperature glass. The emission of complexes 1 a-3 a and 1 b-3 b was assigned to a triplet metal-to-ligand charge-transfer ((3)MLCT) (dpi(Ir)-->pi*(bpy-est and N-C-)) state mixed with some triplet intraligand ((3)IL) (pi-->pi*) (N-C- and N-N) character. However, the emissive states of the pq- and bsb- complexes 4 a, 4 b, 5 a, and 5 b showed substantial (3)IL (pi-->pi*) (pq-/bsb-) character. The lipophilicity of all the complexes was determined by reversed-phase HPLC. Upon binding to estrogen receptor alpha, all of these iridium(III) estradiol conjugates exhibited emission enhancement and lifetime extension, rendering them a novel series of luminescent probes for this receptor.

  6. New Unsymmetrically Benzene-Fused Bis (Tetrathiafulvalene: Synthesis, Characterization, Electrochemical Properties and Electrical Conductivity of Their Materials

    Directory of Open Access Journals (Sweden)

    Tahar Abbaz

    2014-03-01

    Full Text Available The synthesis of new unsymmetrically benzene-fused bis (tetrathiafulvalene has been carried out by a cross-coupling reaction of the respective 4,5-dialkyl-1,3-dithiole-2-selenone 6–9 with 2-(4-(p-nitrophenyl-1,3-dithiole-2-ylidene-1,3,5,7-tetrathia-s-indacene-6-one 5 prepared by olefination of 4-(p-nitrophenyl-1,3-dithiole-2-selenone 3 and 1,3,5,7-tetrathia-s-indacene-2,6-dione 4. The conversion of the nitro moiety 10a–d to amino 11a–d then dibenzylamine 12a–d groups respectively used reduction and alkylation methods. The electron donor ability of these new compounds has been measured by cyclic voltammetry (CV technique. Charge transfer complexes with tetracyanoquino-dimethane (TCNQ were prepared by chemical redox reactions. The complexes have been proven to give conducting materials.

  7. Microwave-assisted one-pot synthesis of metal/metal oxide nanoparticles on graphene and their electrochemical applications

    International Nuclear Information System (INIS)

    Wang Shuangyin; Jiang San Ping; Wang Xin

    2011-01-01

    Graphical abstract: Display Omitted Research highlights: → Microwave polyol method is efficient to deposit nanoparticles on graphene. → SnO 2 /graphene is more efficient than graphene for supercapacitor. → PtRu/graphene is more active than commercial PtRu/C for methanol oxidation. - Abstract: An effective synthesis strategy of hybrid metal (PtRu)/metal oxide (SnO 2 ) nanoparticles on graphene nanocomposites is developed using a microwave-assisted one-pot reaction process. The mixture of ethylene glycol (EG) and water is used as both solvent and reactant. In the reaction system for the synthesis of SnO 2 /graphene nanocomposite, EG not only reduces graphene oxide (GO) to graphene, but also results in the formation of SnO 2 facilitated by the presence of a small amount of water. On the other hand, in the reaction system for preparation of PtRu/graphene nanocomposites, EG acts as solvent and reducing agent for reduction of PtRu nanoparticles from their precursors and reduction of graphene from graphene oxide. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) characterizations confirm the feasibility of the microwave-assisted reaction system to simultaneously reduce graphene oxide and to form SnO 2 or PtRu nanoparticles. The as-synthesized SnO 2 /graphene hybrid composites show a much higher supercapacitance than the pure graphene, and the as-prepared PtRu/graphene show much better electrocatalytic activity for methanol oxidation compared to the commercial E-TEK PtRu/C electrocatalysts.

  8. Synthesis and electrochemical characterization of highly tolerant Pd electrocatalysts as cathodes in direct ethylene glycol fuel cells (DEGFC)

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez Varela, F.J.; Fraire Luna, S. [Cinvestav, Unidad Saltillo, Ramos Arizpe, Coahuila (Mexico)] e-mail: javier.varela@cinvestav.edu.mx; Savadogo, O. [Laboratoire d' Electrochimie et de Materiaux Energetiques, Ecole Polytechnique de Montreal, Montreal, QC (Canada)

    2009-09-15

    Highly selective Pd electrocatalysts were synthesized by the formic acid method and evaluated as cathodes for DEGFC applications. In rotating disc measurements in acid medium, the Pd/C cathode showed important catalytic activity for the Oxygen Reduction Reaction (ORR). In the presence of ethylene glycol (EG, C{sub 2}H{sub 6}O{sub 2}), Pd/C exhibited an excellent electrochemical behavior and full tolerance to the organic molecule. No current density peaks associated to the EG oxidation reaction emerged and the shift in onset potential for the ORR (Eonset) toward more negative potentials was negligible on this cathode. Moreover, the evaluation of Pd/C in a DEGFC operating at 80 degrees Celsius demonstrated its high performance as cathode. As a comparison, commercial Pt/C was tested under the same conditions showing a limited selectivity for the ORR. The detrimental effect of EG on the Pt electrocatalysts resulted in high intensity current density peaks due to the oxidation of EG and a significant shift in Eonset. Given these results, it is expected that highly efficient Pd-based cathodes can find application in DEGFCs. [Spanish] Se sintetizaron electrocatalizadores altamente selectivos mediante el metodo de acido formico y se evaluaron como catodos en aplicaciones de CCGED. En mediciones de disco rotatorio en medio acido, el catodo Pd/C mostro importante actividad catalitica en la reaccion de reduccion de oxigeno (RRO). En la presencia de glicol de etileno (GE, C{sub 2}H{sub 6}O{sub 2}), Pd/C exhibio un excelente comportamiento electromecanico y tolerancia total a la molecula organica. No surgieron picos de densidad de corriente asociados con la reaccion de oxidacion de GE y el corrimiento en el potencial de inicio para la RRO (Einicio) hacia potenciales mas negativos fue despreciable en este catodo. Como comparacion, se probo un Pt/C bajo las mismas condiciones y se observo una selectividad limitada para el RRO. El efecto perjudicial de GE en el electrocatalizador

  9. Controlled synthesis of mesoporous β-Ni(OH){sub 2} and NiO nanospheres with enhanced electrochemical performance

    Energy Technology Data Exchange (ETDEWEB)

    Xing, Shengtao; Wang, Qian [College of Chemistry and Material Sciences, Hebei Normal University, Shijiazhuang 050016 (China); Ma, Zichuan, E-mail: mazc@vip.163.com [College of Chemistry and Material Sciences, Hebei Normal University, Shijiazhuang 050016 (China); Wu, Yinsu; Gao, Yuanzhe [College of Chemistry and Material Sciences, Hebei Normal University, Shijiazhuang 050016 (China)

    2012-09-15

    Highlights: ► Uniform mesoporous β-Ni(OH){sub 2} and NiO nanospheres with hierarchical structures were synthesized by a simple complexation–precipitation method. ► Both ammonia and citrate played an important role for the formation of mesoporous nanospheres. ► β-Ni(OH){sub 2} and NiO nanospheres showed excellent capacitive properties due to their mesoporous structures and larger surface areas. -- Abstract: Uniform mesoporous β-Ni(OH){sub 2} and NiO nanospheres with hierarchical structures were synthesized by a facile complexation–precipitation method. The effects of ammonia and citrate on the structure and morphology of the products were thoroughly investigated by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption–desorption measurements. The results indicated that ammonia played an important role for the formation of flowerlike spheres assembled from nanosheets. The addition of citrate could remarkably reduce the particle sizes and increase the specific surface areas of flowerlike spheres. A possible formation mechanism based on the experimental results was proposed to understand their growing procedures. β-Ni(OH){sub 2} and NiO nanospheres prepared with the addition of citrate showed excellent capacitive properties due to their mesoporous structures and large surface areas, suggesting the importance of controlled synthesis of hierarchical nanostructures for their applications.

  10. Controlled synthesis of mesoporous β-Ni(OH)2 and NiO nanospheres with enhanced electrochemical performance

    International Nuclear Information System (INIS)

    Xing, Shengtao; Wang, Qian; Ma, Zichuan; Wu, Yinsu; Gao, Yuanzhe

    2012-01-01

    Highlights: ► Uniform mesoporous β-Ni(OH) 2 and NiO nanospheres with hierarchical structures were synthesized by a simple complexation–precipitation method. ► Both ammonia and citrate played an important role for the formation of mesoporous nanospheres. ► β-Ni(OH) 2 and NiO nanospheres showed excellent capacitive properties due to their mesoporous structures and larger surface areas. -- Abstract: Uniform mesoporous β-Ni(OH) 2 and NiO nanospheres with hierarchical structures were synthesized by a facile complexation–precipitation method. The effects of ammonia and citrate on the structure and morphology of the products were thoroughly investigated by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption–desorption measurements. The results indicated that ammonia played an important role for the formation of flowerlike spheres assembled from nanosheets. The addition of citrate could remarkably reduce the particle sizes and increase the specific surface areas of flowerlike spheres. A possible formation mechanism based on the experimental results was proposed to understand their growing procedures. β-Ni(OH) 2 and NiO nanospheres prepared with the addition of citrate showed excellent capacitive properties due to their mesoporous structures and large surface areas, suggesting the importance of controlled synthesis of hierarchical nanostructures for their applications.

  11. One-step hydrothermal synthesis and electrochemical performance of sodium-manganese-iron phosphate as cathode material for Li-ion batteries

    Science.gov (United States)

    Karegeya, Claude; Mahmoud, Abdelfattah; Vertruyen, Bénédicte; Hatert, Frédéric; Hermann, Raphaël P.; Cloots, Rudi; Boschini, Frédéric

    2017-09-01

    The sodium-manganese-iron phosphate Na2Mn1.5Fe1.5(PO4)3 (NMFP) with alluaudite structure was obtained by a one-step hydrothermal synthesis route. The physical properties and structure of this material were obtained through XRD and Mössbauer analyses. X-ray diffraction Rietveld refinements confirm a cationic distribution of Na+ and presence of vacancies in A(2)', Na+ and small amounts of Mn2+ in A(1), Mn2+ in M(1), 0.5 Mn2+ and Fe cations (Mn2+,Fe2+ and Fe3+) in M(2), leading to the structural formula Na2Mn(Mn0.5Fe1.5)(PO4)3. The particles morphology was investigated by SEM. Several reactions with different hydrothermal reaction times were attempted to design a suitable synthesis protocol of NMFP compound. The time of reaction was varied from 6 to 48 h at 220 °C. The pure phase of NMFP particles was firstly obtained when the hydrothermal reaction of NMFP precursors mixture was maintained at 220 °C for 6 h. When the reaction time was increased from 6 to 12, 24 and 48 h, the dandelion structure was destroyed in favor of NMFP micro-rods. The combination of NMFP (NMFP-6H, NMFP-12H, NMFP-24H and NMFP-48H) structure refinement and Mössbauer characterizations shows that the increase of the reaction time leads to the progressive increment of Fe(III) and the decrease of the crystal size. The electrochemical tests indicated that NMFP is a 3 V sodium intercalating cathode. The comparison of the discharge capacity evolution of studied NMFP electrode materials at C/5 current density shows different capacities of 48, 40, 34 and 34 mA h g-1 for NMFP-6H, NMFP-12H, NMFP-24H and NMFP-48H respectively. Interestingly, all samples show excellent capacity retention of about 99% during 50 cycles.

  12. Sunlight assisted synthesis of silver nanoparticles in zeolite matrix and study of its application on electrochemical detection of dopamine and uric acid in urine samples

    International Nuclear Information System (INIS)

    Meenakshi, S.; Devi, S.; Pandian, K.; Devendiran, R.; Selvaraj, M.

    2016-01-01

    Sunlight assisted reduction of silver ions were accomplished for the synthesis of silver nanoparticles incorporated within the mesoporous silicate framework of zeolite Y. The zeolite-Y and AgNP/Zeo-Y were characterized by field emission scanning electron microscopy, transmission electron microscopy, N 2 adsorption-desorption BET isotherm and X–ray diffraction techniques. The incorporation of silver nanoparticles within the porous framework was further confirmed by cyclic voltammetry and electrochemical impedance spectroscopy. An enhanced electrocatalytic oxidation of biologically important molecules like dopamine and uric acid using AgNP/Zeo-Y modified glassy carbon electrode has been developed. A simultaneous oxidation of DA and UA peaks were obtained at + 0.31 V and + 0.43 V (vs. Ag/AgCl) using AgNP/Zeo-Y/GCE under the optimum experimental condition. A well-resolved peak potential window (~ 120 mV) for the oxidation of both DA and UA were observed at AgNP/Zeo-Y/GCE system. The calibration curves for DA and UA were obtained within the dynamic linear range of 0.02 × 10 −6 to 0.18 × 10 −6 M (R 2 = 0.9899) and 0.05 × 10 −6 to 0.7 × 10 −6 M (R 2 = 0.9996) and the detection limits were found to be 1.6 × 10 −8 M and 2.51 × 10 −8 M by using differential pulse voltammetry (DPV) method. The proposed method was successfully applied for the determination of both DA and UA in human urine samples with a related standard deviation was < 3%, and n = 5 using the standard addition method. - Highlights: • Sunlight assisted synthesis of AgNP/Zeo-Y via ion exchange method. • Enhanced electrocatalytic peak current values for DA and UA with a well separated peak to peak position. • AgNP/Zeo-Y/GCE for the simultaneous detection of DA and UA by CV and DPV methods. • Detection limit was found to be 1.60 × 10 -8 M and 2.51 × 10 −8 M for DA and UA respectively. • DPV technique was effectively realistic to detect DA and UA in urine samples.

  13. UV-assisted synthesis of surface modified mesoporous TiO{sub 2}/G microspheres and its electrochemical performances in lithium ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Tong, Xiaoling; Zeng, Min, E-mail: zengmin@swust.edu.cn; Li, Jing; Li, Fuyun

    2017-01-15

    Highlights: • We synthesize the surface modified mesoporous TiO{sub 2}/G microspheres, which possess high surface area with 258 m{sup 2} g{sup −1} and narrow pore size at about 7.8 nm. • The surface reaction mechanism of the UV-assisted synthesis mesoporous TiO{sub 2}/G microspheres has been explored. • The as-made TiO{sub 2}/G microspheres exhibit excellent electrochemical performances and deliver a capacity of 141 mAh g{sup −1} upon 100 cycles even at 1 C. - Abstract: Three-dimensional mesoporous TiO{sub 2}/graphene (TiO{sub 2}/G) microspheres have been successfully synthesized through a simple UV-assisted method of reduced graphene oxide with hydrazine. The as-made surface modified mesoporous TiO{sub 2}/G microspheres possess large surface area and exhibit a high initial discharge capacity of 220 mAh g{sup −1} and retain 84% (∼185 mAh g{sup −1}) of reversible capacity over 100 cycles at a rate of 0.2C. In addition, TiO{sub 2}/G microspheres display improved cyclic performance, excellent rate capability and enhanced electrical conductivity, which are superior to the bare TiO{sub 2} microspheres. Furthermore, TiO{sub 2}/G microspheres can achieve a reversible capacity of 141 mAh g{sup −1} upon 100 cycles even at the 1C rate. We believe that the mesoporous TiO{sub 2}/G microspheres are expected to be a promising high performance anode material for the next generation lithium ion batteries.

  14. Synthesis of ZnO micro-pompons by soft template-directed wet chemical method and their application in electrochemical biosensors

    International Nuclear Information System (INIS)

    Zhou, Yu; Wang, Lei; Ye, Zhizhen; Zhao, Minggang; Huang, Jingyun

    2014-01-01

    Highlights: •ZnO micro-pompons (MPs) are synthesized by a controlled soft template-directed route. •ZnO MPs are composed of radial robust nanowires built of numerous nanoparticles. •The structure is ideal for the immobilization of enzymes to maintain their activity. •ZnO MPs are favorable for electron transfer and liquid mobilization. •Good performance of H 2 O 2 biosensor indicates ZnO MPs are promising in biosensing. -- Abstract: ZnO micro-pompons are fabricated by a controlled synthesis route via a soft template-directed wet chemical method followed by a subsequent calcination in air. The achieved ZnO micro-pompons with several hundred micrometers in diameter are composed of a great number of robust nanowires built of numerous nanoparticles. This unique structure is accessible for enzymes to sequester or bind, and the tightly connected nanoparticles facilitate the transmission of electrons, what's more, the large spaces between the nanowires are favorable for the mobilization of the liquid with target substance. In addition, the high electron communication features of ZnO and the tightly connected nanoparticles of the structure also promote the electron transfer between the active sites of proteins and the electrode. The enzymatic electrode fabricated with Horseradish peroxidase immobilized on ZnO micro-pompons along with chitosan covering outside exhibits excellent response for detecting H 2 O 2 with a wide linear range of 0.2–3.4 mM and a high sensitivity of 1395.64 (μA/mM cm 2 ), indicating a great potential in fabricating electrochemical biosensors

  15. Nickel oxide/polypyrrole/silver nanocomposites with core/shell/shell structure: Synthesis, characterization and their electrochemical behaviour with antimicrobial activities

    Energy Technology Data Exchange (ETDEWEB)

    Das, Dhaneswar; Nath, Bikash C. [Department of Chemical Sciences, Tezpur University, Tezpur 784028, Assam (India); Phukon, Pinkee [Department of Molecular Biology and Biotechnology, Tezpur University, Tezpur 784028, Assam (India); Saikia, Bhaskar J.; Kamrupi, Isha R. [Department of Chemical Sciences, Tezpur University, Tezpur 784028, Assam (India); Dolui, Swapan K., E-mail: dolui@tezu.ernet.in [Department of Chemical Sciences, Tezpur University, Tezpur 784028, Assam (India)

    2013-10-01

    Magnetic and conducting Nickel oxide–polypyrrole (NiO/PPy) nanoparticles with core–shell structure were prepared in the presence of Nickel oxide (NiO) in aqueous solution containing sodium dodecyl benzenesulfonate (SDBS) as a surfactant as well as dopant. A stable dispersion of silver (Ag) nanoparticles was synthesized by chemical (citrate reduction) method. NiO/PPy nanocomposites were added to the Ag colloid under stirring. Ag nanoparticles could be electrostatically attracted on the surface of NiO/PPy nanocomposites, leading to formation of NiO/PPy/Ag nanocomposites with core/shell/shell structure. The morphology, structure, particle size and composition of the products were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, cyclic voltammetry (CV) and current–voltage (I–V) analysis. The resultant nanocomposites have the good conductivity and excellent electrochemical and catalytic properties of PPy and Ag nanoparticles. Furthermore, the nanocomposites showed excellent antibacterial behaviour due to the presence of Ag nanoparticles in the composite. The thermal stability of NiO–PPy as well as NiO/PPy/Ag nanocomposites was higher than that of pristine PPy. Studies of IR spectra suggest that the increased thermal stability may be due to interactions between NiO and Ag nanoparticles with the PPy backbone. - Highlights: • NiO nanoparticles were synthesized by two step soft chemical synthesis route. • Ag nanoparticles were prepared by using citrate reduction method. • NiO/PPy nanocomposites are synthesized by chemical oxidative polymerization process. • NiO/PPy/Ag nanocomposites can be used in the water purification technology.

  16. Graphene quantum dots decorated with magnetic nanoparticles: Synthesis, electrodeposition, characterization and application as an electrochemical sensor towards determination of some amino acids at physiological pH

    Energy Technology Data Exchange (ETDEWEB)

    Hasanzadeh, Mohammad, E-mail: mhmmd_hasanzadeh@yahoo.com [Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz 51664 (Iran, Islamic Republic of); Pharmaceutical Analysis Research Center, Tabriz University of Medical Sciences, Tabriz 51664 (Iran, Islamic Republic of); Karimzadeh, Ayub [Department of Biochemistry, Higher Education Institute of Rab-Rashid, Tabriz (Iran, Islamic Republic of); School of Medicine, Gonabad University of Medical Sciences, Gonabad (Iran, Islamic Republic of); Shadjou, Nasrin [Department of Nanochemistry, Nano Technology Research Center, Urmia University, Urmia 57154 (Iran, Islamic Republic of); Department of Nano Technology, Faculty of Science, Urmia University, Urmia 57154 (Iran, Islamic Republic of); Mokhtarzadeh, Ahad [School of Medicine, Gonabad University of Medical Sciences, Gonabad (Iran, Islamic Republic of); Department of Biochemistry, Higher Education Institute of Rab-Rashid, Tabriz (Iran, Islamic Republic of); Bageri, Leyla [Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz 51664 (Iran, Islamic Republic of); Sadeghi, Sattar; Mahboob, Soltanali [Department of Biochemistry, Higher Education Institute of Rab-Rashid, Tabriz (Iran, Islamic Republic of)

    2016-11-01

    This study reports on the synthesis and characterization of a novel nano-composite, Fe{sub 3}O{sub 4} magnetic nanoparticles/graphene quantum dots (Fe{sub 3}O{sub 4} MNP-GQDs), for sensing of some amino acids. For the first time, as-synthesized GQDs and Fe{sub 3}O{sub 4} MNPs-GQDs was electrodeposited on the glassy carbon electrode (GCE) by cyclic voltammetry (CV) regime in the potential range from − 1.0 to 1.0 V. Fe{sub 3}O{sub 4} MNP-GQDs is engineered to specifically and effectively capture and enhancement the electrochemical signals of some amino acids at physiological pH due to the synergy among GQDs and magnetic nanoparticles. We have illustrated that the obtained Fe{sub 3}O{sub 4} MNPs-GQDs exhibited a much higher electroactivity individual GQDs and Fe{sub 3}O{sub 4} MNPs for the electrooxidation and detection of amino acid which was about 10 fold higher than for GQDs. Magnetic and specific properties of the Fe{sub 3}O{sub 4} MNP-GQDs can be exploited to capture and pre-concentration the amino acids onto its surface, which are important for detection of multi-amino acids. - Highlights: • Electrooxidation of amino acids was performed using Fe{sub 3}O{sub 4} MNP-GQDs. • Modified electrode shows new advantages as an amino acids sensor. • Excellent electrocatalytic activity was obtained for amino acids oxidation.

  17. Nickel oxide/polypyrrole/silver nanocomposites with core/shell/shell structure: Synthesis, characterization and their electrochemical behaviour with antimicrobial activities

    International Nuclear Information System (INIS)

    Das, Dhaneswar; Nath, Bikash C.; Phukon, Pinkee; Saikia, Bhaskar J.; Kamrupi, Isha R.; Dolui, Swapan K.

    2013-01-01

    Magnetic and conducting Nickel oxide–polypyrrole (NiO/PPy) nanoparticles with core–shell structure were prepared in the presence of Nickel oxide (NiO) in aqueous solution containing sodium dodecyl benzenesulfonate (SDBS) as a surfactant as well as dopant. A stable dispersion of silver (Ag) nanoparticles was synthesized by chemical (citrate reduction) method. NiO/PPy nanocomposites were added to the Ag colloid under stirring. Ag nanoparticles could be electrostatically attracted on the surface of NiO/PPy nanocomposites, leading to formation of NiO/PPy/Ag nanocomposites with core/shell/shell structure. The morphology, structure, particle size and composition of the products were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, cyclic voltammetry (CV) and current–voltage (I–V) analysis. The resultant nanocomposites have the good conductivity and excellent electrochemical and catalytic properties of PPy and Ag nanoparticles. Furthermore, the nanocomposites showed excellent antibacterial behaviour due to the presence of Ag nanoparticles in the composite. The thermal stability of NiO–PPy as well as NiO/PPy/Ag nanocomposites was higher than that of pristine PPy. Studies of IR spectra suggest that the increased thermal stability may be due to interactions between NiO and Ag nanoparticles with the PPy backbone. - Highlights: • NiO nanoparticles were synthesized by two step soft chemical synthesis route. • Ag nanoparticles were prepared by using citrate reduction method. • NiO/PPy nanocomposites are synthesized by chemical oxidative polymerization process. • NiO/PPy/Ag nanocomposites can be used in the water purification technology

  18. Electrochemical biosensors

    CERN Document Server

    Cosnier, Serge

    2015-01-01

    "This is an excellent book on modern electrochemical biosensors, edited by Professor Cosnier and written by leading international experts. It covers state-of-the-art topics of this important field in a clear and timely manner."-Prof. Joseph Wang, UC San Diego, USA  "This book covers, in 13 well-illustrated chapters, the potential of electrochemical methods intimately combined with a biological component for the assay of various analytes of biological and environmental interest. Particular attention is devoted to the description of electrochemical microtools in close contact with a biological cell for exocytosis monitoring and to the use of nanomaterials in the electrochemical biosensor architecture for signal improvement. Interestingly, one chapter describes the concept and design of self-powered biosensors derived from biofuel cells. Each topic is reviewed by experts very active in the field. This timely book is well suited for providing a good overview of current research trends devoted to electrochemical...

  19. In situ synthesis, electrochemical and quantum chemical analysis of an amino acid-derived ionic liquid inhibitor for corrosion protection of mild steel in 1M HCl solution

    International Nuclear Information System (INIS)

    Kowsari, E.; Arman, S.Y.; Shahini, M.H.; Zandi, H.; Ehsani, A.; Naderi, R.; PourghasemiHanza, A.; Mehdipour, M.

    2016-01-01

    Highlights: • Electrochemical analysis of effectiveness of an amino acid-derived ionic liquid inhibitor. • Quantum chemical analysis of effectiveness of an amino acid-derived ionic liquid inhibitor. • Finding correlation between electrochemical analysis and quantum chemical analysis. - Abstract: In this study, an amino acid-derived ionic liquid inhibitor, namely tetra-n-butyl ammonium methioninate, was synthesized and the role this inhibitor for corrosion protection of mild steel exposed to 1.0 M HCl was investigated using electrochemical, quantum and surface analysis. By taking advantage of potentiodynamic polarization, the inhibitory action of tetra-n-butyl ammonium methioninate was found to be mainly mixed-type with dominant anodic inhibition. The effectiveness of the inhibitor was also indicated using electrochemical impedance spectroscopy (EIS). Moreover, to provide further insight into the mechanism of inhibition, electrochemical noise (EN) and quantum chemical calculations of the inhibitor were performed.

  20. SHORT COMMUNICATION SYNTHESIS AND PRELIMINARY ...

    African Journals Online (AJOL)

    a

    2006 Chemical Society of Ethiopia ... 1Department of Chemistry, School of Pure & Applied Sciences, The University of the South. Pacific, Post ... bonding and stereochemistry [1-3], whereas their semicarbazones analogs received much less.

  1. Electrochemical analysis

    International Nuclear Information System (INIS)

    Hwang, Hun

    2007-02-01

    This book explains potentiometry, voltametry, amperometry and basic conception of conductometry with eleven chapters. It gives the specific descriptions on electrochemical cell and its mode, basic conception of electrochemical analysis on oxidation-reduction reaction, standard electrode potential, formal potential, faradaic current and faradaic process, mass transfer and overvoltage, potentiometry and indirect potentiometry, polarography with TAST, normal pulse and deferential pulse, voltammetry, conductometry and conductometric titration.

  2. Electrochemically assisted organosol method for Pt-Sn nanoparticle synthesis and in situ deposition on graphite felt support: Extended reaction zone anodes for direct ethanol fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Lycke, Derek R.; Gyenge, Elod L. [Department of Chemical and Biological Engineering, The University of British Columbia, 2360 East Mall, Vancouver, BC (Canada)

    2007-03-20

    Two electrochemically assisted variants of the Boenneman organosol method were developed for Pt-Sn nanoparticle synthesis and in situ deposition on graphite felt electrodes (e.g. thickness up to 2 mm). Tetraoctylammonium triethylhydroborate N(C{sub 8}H{sub 17}){sub 4}BH(C{sub 2}H{sub 5}){sub 3} was employed as colloid stabilizer and reductant dissolved in tetrahydrofuran (THF). The role of the electric field at a low deposition current density of 1.25 mA cm{sup -2} was mainly electrophoretic causing the migration and adsorption of N(C{sub 8}H{sub 17}){sub 4}BH(C{sub 2}H{sub 5}){sub 3} on the graphite felt surface where it reduced the PtCl{sub 2}-SnCl{sub 2} mixture. Faradaic electrodeposition was detected mostly for Sn. Typical Pt-Sn loadings were between 0.4 and 0.9 mg cm{sup -2} depending on the type of pre-deposition exposure of the graphite felt: surfactant-adsorption and metal-adsorption variant, respectively. The catalyst surface area and Pt:Sn surface area ratio was determined by anodic striping of an underpotential deposited Cu monolayer. The two deposition variants gave different catalyst surfaces: total area 233 and 76 cm{sup 2} mg{sup -1}, with Pt:Sn surface area ratio of 3.5:1 and 7.7:1 for surfactant and metal adsorption, respectively. Regarding electrocatalysis of ethanol oxidation, voltammetry and chronopotentiometry studies corroborated by direct ethanol fuel cell experiments using 0.5 M H{sub 2}SO{sub 4} as electrolyte, showed that due to a combination of higher catalyst load and Pt:Sn surface ratio, the graphite felt anodes prepared by the metal-adsorption variant gave better performance. The catalyzed graphite felt provided an extended reaction zone for ethanol electrooxidation and it gave higher catalyst mass specific peak power outputs compared to literature data obtained using gas diffusion anodes with carbon black supported Pt-Sn nanoparticles. (author)

  3. Synthesis, structure and electrochemical properties of LiNaCo{sub 0.5}Fe{sub 0.5}PO{sub 4}F fluoride-phosphate

    Energy Technology Data Exchange (ETDEWEB)

    Fedotov, Stanislav S. [Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow (Russian Federation); Skoltech Center for Electrochemical Energy Storage, Skolkovo Institute of Science and Technology, 143026 Moscow (Russian Federation); Kuzovchikov, Sergey M.; Khasanova, Nellie R.; Drozhzhin, Oleg A.; Filimonov, Dmitriy S. [Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow (Russian Federation); Karakulina, Olesia M.; Hadermann, Joke [EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Abakumov, Artem M. [Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow (Russian Federation); Skoltech Center for Electrochemical Energy Storage, Skolkovo Institute of Science and Technology, 143026 Moscow (Russian Federation); EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Antipov, Evgeny V. [Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow (Russian Federation)

    2016-10-15

    LiNaCo{sub 0.5}Fe{sub 0.5}PO{sub 4}F fluoride-phosphate was synthesized via conventional solid-state and novel freeze-drying routes. The crystal structure was refined based on neutron powder diffraction (NPD) data and validated by electron diffraction (ED) and high-resolution transmission electron microscopy (HRTEM). The alkali ions are ordered in LiNaCo{sub 0.5}Fe{sub 0.5}PO{sub 4}F and the transition metals jointly occupy the same crystallographic sites. The oxidation state and oxygen coordination environment of the Fe atoms were verified by {sup 57}Fe Mössbauer spectroscopy. Electrochemical tests of the LiNaCo{sub 0.5}Fe{sub 0.5}PO{sub 4}F cathode material demonstrated a reversible activity of the Fe{sup 3+}/Fe{sup 2+} redox couple at the electrode potential near 3.4 V and minor activity of the Co{sup 3+}/Co{sup 2+} redox couple over 5 V vs Li/Li{sup +}. The material exhibited the discharge capacity of more than 82% (theo.) regarding Fe{sup 3+}/Fe{sup 2+} in the 2.4÷4.6 V vs Li/Li{sup +} potential range. - Graphical abstract: The ball-polyhedral representation of the LiNaCo{sub 0.5}Fe{sub 0.5}PO{sub 4}F crystal structure. The MO{sub 4}F{sub 2} units are depicted as blue octahedra, PO{sub 4} units as orange tetrahedra, sodium atoms are designated as yellow (Na1), lithium – red and brown (Li2, Li3 resp.), fluorine – green, oxygen – violet spheres. - Highlights: • Freeze-drying method was successfully applied to the synthesis of LiNaCo{sub 0.5}Fe{sub 0.5}PO{sub 4}F. • The crystal structure of LiNaCo{sub 0.5}Fe{sub 0.5}PO{sub 4}F was refined based on NPD and validated by ED and HRTEM. • LiNaCo{sub 0.5}Fe{sub 0.5}PO{sub 4}F demonstrated a reversible Li de/intercalation in the 2.5÷4.6 V vs Li/Li{sup +} range.

  4. Novel electrochemical redox-active species: one-step synthesis of polyaniline derivative-Au/Pd and its application for multiplexed immunoassay

    Science.gov (United States)

    Wang, Liyuan; Feng, Feng; Ma, Zhanfang

    2015-11-01

    Electrochemical redox-active species play crucial role in electrochemically multiplexed immunoassays. A one-pot method for synthesizing four kinds of new electrochemical redox-active species was reported using HAuCl4 and Na2PdCl4 as dual oxidating agents and aniline derivatives as monomers. The synthesized polyaniline derivative-Au/Pd composites, namely poly(N-methyl-o-benzenediamine)-Au/Pd, poly(N-phenyl-o-phenylenediamine)-Au/Pd, poly(N-phenyl-p-phenylenediamine)-Au/Pd and poly(3,3’,5,5’-tetramethylbenzidine)-Au/Pd, exhibited electrochemical redox activity at -0.65 V, -0.3 V, 0.12 V, and 0.5 V, respectively. Meanwhile, these composites showed high H2O2 electrocatalytic activity because of the presence of Au/Pd. The as-prepared composites were used as electrochemical immunoprobes in simultaneous detection of four tumor biomarkers (carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (CA199), carbohydrate antigen 72-4 (CA724), and alpha fetoprotein (AFP)). This immunoassay shed light on potential applications in simultaneous gastric cancer (related biomarkers: CEA, CA199, CA724) and liver cancer diagnosis (related biomarkers: CEA, CA199, AFP). The present strategy to the synthesize redox species could be easily extended to other polymers such as polypyrrole derivatives and polythiophene derivatives. This would be of great significance in the electrochemical detection of more analytes.

  5. Synthesis, crystal structure, antimicrobial activity and electrochemistry study of chromium(III) and copper(II) complexes based on semicarbazone Schiff base and azide ligands

    Czech Academy of Sciences Publication Activity Database

    Shaabani, B.; Khandar, A.A.; Dušek, Michal; Pojarová, Michaela; Mahmoudi, F.

    2013-01-01

    Roč. 394, JAN (2013), s. 563-568 ISSN 0020-1693 Grant - others:AV ČR(CZ) AP0701 Program:Akademická prémie - Praemium Academiae Institutional support: RVO:68378271 Keywords : antimicrobial activity * azide ligand * metal complex * Schiff base ligand * X-ray structure Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.041, year: 2013

  6. Synthesis, spectral characterization and structural studies of a novel O, N, O donor semicarbazone and its binuclear copper complex with hydrogen bond stabilized lattice

    Science.gov (United States)

    Layana, S. R.; Saritha, S. R.; Anitha, L.; Sithambaresan, M.; Sudarsanakumar, M. R.; Suma, S.

    2018-04-01

    A novel O,N,O donor salicylaldehyde-N4-phenylsemicarbazone, (H2L) has been synthesized and physicochemically characterized. Detailed structural studies of H2L using single crystal X-ray diffraction technique reveals the existence of intra and inter molecular hydrogen bonding interactions, which provide extra stability to the molecule. We have successfully synthesized a binuclear copper(II) complex, [Cu2(HL)2(NO3)(H2O)2]NO3 with phenoxy bridging between the two copper centers. The complex was characterized by elemental analysis, magnetic susceptibility and conductivity measurements, FT-IR, UV-Visible, mass and EPR spectral methods. The grown crystals of the copper complex were employed for the single crystal X-ray diffraction studies. The complex possesses geometrically different metal centers, in which the ligand coordinates through ketoamide oxygen, azomethine nitrogen and deprotonated phenoxy oxygen. The extensive intermolecular hydrogen bonding interactions of the coordinated and the lattice nitrate groups interconnect the complex units to form a 2D supramolecular assembly. The ESI mass spectrum substantiates the existence of 1:1 complex. The g values obtained from the EPR spectrum in frozen DMF suggest dx2 -y2 ground state for the unpaired electron.

  7. ELECTROCHEMICAL SYNTHESIS AND CHARACTERIZATION OF ...

    African Journals Online (AJOL)

    Using simple electrosynthesis methods a single and bilayer of conducting ... metal oxides [5-8], carbon nanomaterials [5-8], polyoxometalates [9-12], and quinone .... where C is the specific capacitance in farads per grams (F/g), i is current ...

  8. Electrochemical capacitor

    Science.gov (United States)

    Anderson, Marc A.; Liu, Kuo -Chuan; Mohr, Charles M.

    1999-10-05

    An inexpensive porous metal oxide material having high surface area, good conductivity and high specific capacitance is advantageously used in an electrochemical capacitor. The materials are formed in a sol-gel process which affords control over the properties of the resultant metal oxide materials.

  9. Electrochemical construction

    Science.gov (United States)

    Einstein, Harry; Grimes, Patrick G.

    1983-08-23

    An electrochemical cell construction features a novel co-extruded plastic electrode in an interleaved construction with a novel integral separator-spacer. Also featured is a leak and impact resistant construction for preventing the spill of corrosive materials in the event of rupture.

  10. Electrochemical device

    Science.gov (United States)

    Grimes, Patrick G.; Einstein, Harry; Bellows, Richard J.

    1988-01-12

    A tunnel protected electrochemical device features channels fluidically communicating between manifold, tunnels and cells. The channels are designed to provide the most efficient use of auxiliary power. The channels have a greater hydraulic pressure drop and electrical resistance than the manifold. This will provide a design with the optimum auxiliary energy requirements.

  11. Electrochemical Cell

    DEFF Research Database (Denmark)

    1999-01-01

    The invention relates to a rechargeable electrochemical cell comprising a negative electrode, an electrolyte and a positive electrode in which the positive electrode structure comprises a lithium cobalt manganese oxide of the composition Li¿2?Co¿y?Mn¿2-y?O¿4? where 0 ... for capacity losses in lithium ion cells and lithium-alloy cells....

  12. Space-Confined Synthesis of Three-Dimensional Boron/Nitrogen-Doped Carbon Nanotubes/Carbon Nanosheets Line-in-Wall Hybrids and Their Electrochemical Energy Storage Applications

    DEFF Research Database (Denmark)

    Zhu, Shan; Li, Jiajun; Li, Qingfeng

    2016-01-01

    paths and reinforcing the whole architecture. As a result, the 3D LIW-NB shows excellent electrochemical properties: as the electrode of supercapacitors, LIW-NB exhibits high specific capacity at different current densities (389 F g-1 at 1 A g-1 and 129 F g-1 at 20 Ag-1); as the lithium ion battery...

  13. Design and synthesis of hierarchical MnO2 nanospheres/carbon nanotubes/conducting polymer ternary composite for high performance electrochemical electrodes.

    Science.gov (United States)

    Hou, Ye; Cheng, Yingwen; Hobson, Tyler; Liu, Jie

    2010-07-14

    For efficient use of metal oxides, such as MnO(2) and RuO(2), in pseudocapacitors and other electrochemical applications, the poor conductivity of the metal oxide is a major problem. To tackle the problem, we have designed a ternary nanocomposite film composed of metal oxide (MnO(2)), carbon nanotube (CNT), and conducting polymer (CP). Each component in the MnO(2)/CNT/CP film provides unique and critical function to achieve optimized electrochemical properties. The electrochemical performance of the film is evaluated by cyclic voltammetry, and constant-current charge/discharge cycling techniques. Specific capacitance (SC) of the ternary composite electrode can reach 427 F/g. Even at high mass loading and high concentration of MnO(2) (60%), the film still showed SC value as high as 200 F/g. The electrode also exhibited excellent charge/discharge rate and good cycling stability, retaining over 99% of its initial charge after 1000 cycles. The results demonstrated that MnO(2) is effectively utilized with assistance of other components (fFWNTs and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) in the electrode. Such ternary composite is very promising for the next generation high performance electrochemical supercapacitors.

  14. Synthesis and electrochemical probing of water-soluble poly(sodium 4-styrenesulfonate-co-acrylic acid)-grafted multiwalled carbon nanotubes

    International Nuclear Information System (INIS)

    Du Feipeng; Yang Yingkui; Xie Xiaolin; Wu Kangbing; Gan Tian; Liu Lang

    2008-01-01

    Water-soluble poly(sodium 4-styrenesulfonate-co-acrylic acid)-grafted multiwalled carbon nanotubes (MWNT-g-P(SSS-co-AA)) with core-shell nanostructure were successfully synthesized by in situ free radical copolymerization of sodium 4-strenesulfonate (SSS) and acrylic acid (AA) in the presence of MWNTs terminated with vinyl groups; their structure was characterized by FTIR, 1 H NMR, Raman, TGA and TEM. The results showed that the thickness and content of the copolymer layer grafted onto the MWNT surface are about 7-12 nm and 82.3%, respectively. The P(SSS-co-AA) covalently grafted on MWNTs provides MWNT-g-P(SSS-co-AA) with good hydrophilicity and solubility in water. Then a novel MWNT-g-P(SSS-co-AA)-modified glassy carbon electrode was fabricated by coating; its electrochemical properties were evaluated by electrochemical probe of K 3 [Fe(CN) 6 ], and its catalytic behaviors to the electrochemical oxidation processes of dopamine (DA) and serotonin (5-HT) were investigated. Since the MWNT-g-P(SSS-co-AA)-modified electrode possesses strong electron transfer capability, high electrochemical activity and catalytic ability, it can be used in sensitive, selective, rapid and simultaneous monitoring of biomolecules

  15. Recent advances in synthesis of three-dimensional porous graphene and its applications in construction of electrochemical (bio)sensors for small biomolecules detection.

    Science.gov (United States)

    Lu, Lu

    2018-07-01

    Electrochemical (bio)sensors have attracted much attention due to their high sensitivity, fast response time, biocompatibility, low cost and easy miniaturization. Specially, ever-growing necessity and interest have given rise to the fast development of electrochemical (bio)sensors for the detection of small biomolecules. They play enormous roles in the life processes with various biological function, such as life signal transmission, genetic expression and metabolism. Moreover, their amount in body can be used as an indicator for diagnosis of many diseases. For example, an abnormal concentration of blood glucose can indicate hyperglycemia or hypoglycemia. Graphene (GR) shows great applications in electrochemical (bio)sensors. Compared with two-dimensional (2D) GR that is inclined to stack together due to the strong π-π interaction, monolithic 3D porous GR has larger specific area, superior mechanical strength, better stability, higher conductivity and electrocatalytic activity. So they attracted more and increasing attention as sensing materials for small biomolecules. This review focuses on the recent advances and strategies in the fabrication methods of 3D porous GR and the development of various electrochemical (bio)sensors based on porous GR and its nanocomposites for the detection of small biomolecules. The challenges and future efforts direction of high-performance electrochemical (bio)sensors based on 3D porous GR for more sensitive analysis of small biomolecules are discussed and proposed. It will give readers an overall understanding of their progress and provide some theoretical guidelines for their future efforts and development. Copyright © 2018 Elsevier B.V. All rights reserved.

  16. Synthesis of ZnCo{sub 2}O{sub 4} microspheres with Zn{sub 0.33}Co{sub 0.67}CO{sub 3} precursor and their electrochemical performance

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Lin; Xu, Shan; Luo, Zhaohui; Wang, Shiquan, E-mail: wsqhao@126.com; Li, Guohua; Feng, Chuanqi [Hubei University, Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Ministry-of-Education Key Laboratory for Synthesis and Applications of Organic Functional Molecules (China)

    2016-07-15

    Zn{sub 0.33}Co{sub 0.67}CO{sub 3} (ZCCO) microspheres are fabricated by a facile solvothermal method at different temperatures, and ZnCo{sub 2}O{sub 4} (ZCO) microspheres were further obtained by pyrolysis of the relative ZCCO precursors at 450 °C. All samples were characterized by X-ray diffractometer, Fourier transform infrared spectra, thermogravimetric, scanning electron microscopy, transmission electron microscopy and Brunauer–Emmett–Teller (BET). Their electrochemical properties were investigated as the anode materials for the lithium-ion battery applications. The results showed that both the ZCCO and ZCO electrodes possess high specific capacities, and the synthesis temperature greatly influenced their performances. Compared with the synthesized of 180 °C, the synthesized of 200 °C (ZCCO-200) exhibited higher discharge capacity (1530 mAh g{sup −1}) and better rate performance with the reversible capacity of 876 mAh g{sup −1} after 70 cycles under the voltage range of 0.01–3.0 V at the current density of 100 mA g{sup −1}. The as-obtained ZCO microspheres from the pyrolysis of ZCCO-200 also exhibited higher discharge capacity of 1416 mAh g{sup −1} and better cycling stability (741 mAh g{sup −1} after 70 cycles) than that for the microspheres from the pyrolysis of ZCO-180, indicating that the electrochemical properties of ZCO may be related to the electrochemical performance of ZCCO. Our present work suggested that both the ZCCO and ZCO microspheres can be promising candidates as novel anode materials for lithium-ion battery applications.

  17. Sol-Gel Synthesis, Electrochemical Characterization, and Stability Testing of Ti0.7W0.3O2 Nanoparticles for Catalyst Support Applications in Proton-Exchange Membrane Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Subban, Chinmayee V. [Cornell Univ., Ithaca, NY (United States); Zhou, Qin [Cornell Univ., Ithaca, NY (United States); Hu, Anthony [Cornell Univ., Ithaca, NY (United States); Moylan, Thomas E. [General Motors Research and Development, Warren, MI (United States); Wagner, Frederick T. [General Motors Research and Development, Warren, MI (United States); DiSalvo, Francis J. [Cornell Univ., Ithaca, NY (United States)

    2010-11-19

    The materials currently used in proton-exchange membrane fuel cells (PEMFCs) require complex control of operating conditions to make them sufficiently durable to permit commercial deployment. One of the major materials challenges to allow simplification of fuel cell operating strategies is the discovery of catalyst supports that are much more stable to oxidative decomposition than currently used carbon blacks. Here we report the synthesis and characterization of Ti0.7W0.3O2 nanoparticles (approximately 50 nm diameter), a promising doped metal oxide that is a candidate for such a durable catalyst support. The synthesized nanoparticles were platinized, characterized by electrochemical testing, and evaluated for stability under PEMFC and other oxidizing acidic conditions. Ti0.7W0.3O2 nanoparticles show no evidence of decomposition when heated in a Nafion solution for 3 weeks at 80 °C. In contrast, when heated in sulfuric, nitric, perchloric, or hydrochloric acid, the oxide reacts to form salts such as titanylsulfatehydrate from sulfuric acid. Electrochemical tests show that rates of hydrogen oxidation and oxygen reduction by platinum nanoparticles supported on Ti0.7W0.3O2 are comparable to those of commercial Pt on carbon black.

  18. Synthesis of nano-particles by soft chemistry: structural, morphological and dimensional control. Studies of the electrochemical properties (towards dyes solar cells)

    International Nuclear Information System (INIS)

    Cassaignon, S.; Koelsch, M.; Jolivet, J.P.

    2006-01-01

    In this work are described the electrochemical behaviour of different TiO 2 films (anatase, brookite and rutile) in aqueous solution and the influence of the parameters as the crystal structure and the morphology on the electrochemical answer. To complete this study, the capacity of the double layer has been measured by impedance spectroscopy. Voltage measurements of TiO 2 sensitized by a dye will allow to discuss the reversibility of the system and the rearrangement mechanisms. At last, the influence of the nature of the TiO 2 particles (anatase, rutile and brookite) on the photovoltage has been studied in order to estimate their interest for photovoltaic devices. (O.M.)

  19. The electrochemical synthesis and corrosion behaviour of TiO2/poly(indole-co-aniline multilayer coating: Experimental and theoretical approach

    Directory of Open Access Journals (Sweden)

    Serap Toprak Döşlü

    2018-01-01

    Full Text Available The aim of this study was to protect stainless steel against corrosion via poly (indole-co-aniline with the help of titanium dioxide pre-coating. Different monomer ratios (1:1 and 1:9 were applied in order to determine the suitable chain composition to synthesize the copolymer in lithium perchlorate containing acetonitrile. The structures, morphologies, electrochemical properties and corrosion resistances of the mono and multi-layer coatings were investigated by Fourier-transform infrared spectra, scanning electron microscope, energy dispersive X-ray spectrometer, electrochemical impedance spectroscopy and anodic polarization. Furthermore the geometric structure and electronic properties of indole, aniline, and indole-co-aniline (dimmer molecules have been investigated by quantum calculations. The results indicated that corrosion protection of copolymers was increased via titanium dioxide pre-coating. The 1:1 copolymer coating showed better corrosion prevention than 1:9 coating. The correlation was determined between experimental and theoretical parameters.

  20. Synthesis and electrochemical performances of ZnO/MnO2 sea urchin-like sleeve array as anode materials for lithium-ion batteries

    International Nuclear Information System (INIS)

    Fang, J.; Yuan, Y.F.; Wang, L.K.; Ni, H.L.; Zhu, H.L.; Yang, J.L.; Gui, J.S.; Chen, Y.B.; Guo, S.Y.

    2013-01-01

    MnO 2 is electrodeposited onto ZnO nanorod array grown on Ni foil, forming a binder-free ZnO/MnO 2 composited electrode. XRD, EDS, SEM and TEM are used to analyze the phase and microstructure of this composite. Burr-like MnO 2 nanoflakes grows on ZnO nanorod array, the top of the composite is hollow and at the bottom exists ZnO large block core as an internal support, forming ZnO/MnO 2 sea urchin-like sleeve array. As anode material for lithium ion batteries, ZnO/MnO 2 sleeve array exhibits higher discharge capacity and coulombic efficiency, better rate performance and cycling stability than single ZnO nanorod array or directly electrodepsited MnO 2 , and the composite effect is very remarkable. After 100 cycles, the discharge capacity of ZnO/MnO 2 still reaches 1259 mA h g −1 , and coulombic efficiency surpasses 98%, higher than those of ZnO nanorod array (111 mA h g −1 ) and directly electrodeposited MnO 2 (507 mA h g −1 ). The improvement of the electrochemical performances is due to the unique sea urchin-like sleeve array architecture. MnO 2 burr tube shell structure leads to high electrochemical activity while the internal ZnO core support ensures good structure stability. The gradually opening of sea urchin-like sleeve during the cycling further enhances the electrochemical activity of MnO 2 , stabilizing and increasing electrochemical performances of the ZnO/MnO 2 composite

  1. Facile synthesis of core–shell structured PANI-Co{sub 3}O{sub 4} nanocomposites with superior electrochemical performance in supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Hai, Zhenyin [Key Laboratory of Instrumentation and Dynamic Measurement of Ministry of Education, North University of China, Taiyuan, Shanxi 030051 (China); Gao, Libo [Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Hong Kong SAR, Kowloon 999077 (Hong Kong); Zhang, Qiang [Key Laboratory of Instrumentation and Dynamic Measurement of Ministry of Education, North University of China, Taiyuan, Shanxi 030051 (China); Xu, Hongyan [School of Materials Science and Engineering, North University of China, Taiyuan, Shanxi 030051 (China); Cui, Danfeng; Zhang, Zengxing [Key Laboratory of Instrumentation and Dynamic Measurement of Ministry of Education, North University of China, Taiyuan, Shanxi 030051 (China); Tsoukalas, Dimitris [Department of Applied Physics, National Technical University of Athens, Zografou GR-15780 (Greece); Tang, Jun; Yan, Shubin [Key Laboratory of Instrumentation and Dynamic Measurement of Ministry of Education, North University of China, Taiyuan, Shanxi 030051 (China); Xue, Chenyang, E-mail: xuechenyang@nuc.edu.cn [Key Laboratory of Instrumentation and Dynamic Measurement of Ministry of Education, North University of China, Taiyuan, Shanxi 030051 (China)

    2016-01-15

    Graphical abstract: - Highlights: • PANI-Co{sub 3}O{sub 4} is synthesized by carbon-assisted and in situ polymerization methods. • PANI coating improves the properties of Co{sub 3}O{sub 4} affecting electrochemical performance. • The nanocomposites exhibit a high specific capacitance of 1184 F g{sup −1} at 1.25 A g{sup −1}. - Abstract: Core–shell structured PANI-Co{sub 3}O{sub 4} nanocomposites for supercapacitor applications were synthesized by combination of carbon-assisted method and in situ polymerization method. The crystalline structure, optical band gap, morphology, and hydrophilic property, as the major factors affecting the performances of supercapacitors, were investigated by X-ray diffraction (XRD), UV–vis spectrophotometry (UV–vis), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and water contact angle (WCA). The core–shell structured PANI-Co{sub 3}O{sub 4} nanocomposites are characterized by amorphous PANI, small bandgaps, large surface area and favorable hydrophilicity, which indicates the superior electrochemical performances of the nanocomposites as electrode material for supercapacitors. Cyclic voltammetry (CV), galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS) measurements were conducted in 6 M KOH aqueous solution to evaluate the electrochemical performances. The results shows that core–shell structured PANI-Co{sub 3}O{sub 4} nanocomposites exhibit a high specific capacitance of 1184 F g{sup −1} at 1.25 A g{sup −1}, excellent cycling stability of a capacitance retention of 84.9% after 1000 galvanostatic charge/discharge cycles, good electrical conductivity and ion diffusion behavior.

  2. Single step synthesis of gold-amino acid composite, with the evidence of the catalytic hydrogen atom transfer (HAT) reaction, for the electrochemical recognition of Serotonin

    Science.gov (United States)

    Choudhary, Meenakshi; Siwal, Samarjeet; Nandi, Debkumar; Mallick, Kaushik

    2016-03-01

    A composite architecture of amino acid and gold nanoparticles has been synthesized using a generic route of 'in-situ polymerization and composite formation (IPCF)' [1,2]. The formation mechanism of the composite has been supported by a model hydrogen atom (H•≡H++e-) transfer (HAT) type of reaction which belongs to the proton coupled electron transfer (PCET) mechanism. The 'gold-amino acid composite' was used as a catalyst for the electrochemical recognition of Serotonin.

  3. A facile synthesis of α-MnO2 used as a supercapacitor electrode material: The influence of the Mn-based precursor solutions on the electrochemical performance

    Science.gov (United States)

    Li, Wenyao; Xu, Jiani; Pan, Yishuang; An, Lei; Xu, Kaibing; Wang, Guangjin; Yu, Zhishui; Yu, Li; Hu, Junqing

    2015-12-01

    Three types of α-MnO2 nanomaterials are synthesized in different Mn-based precursor solutions by using a facile electrochemical deposition at the same depositional condition. The relationships between the precursor solutions and corresponding MnO2 nanomaterials' morphology as well as the electrochemical performance have been studied. As an electrode, electrochemical measurements show that the MnO2 deposited in MnCl2 precursor solution (MnO2-P3) exhibits an enhanced specific capacitance (318.9 F g-1 at 2 mV s-1). Moreover, this electrode demonstrates a good rate capability with 44% retention, which is higher than the MnO2-P1 deposited with Mn(CH3COOH)2 solution and the MnO2-P2 deposited with Mn(NO3)2 precursor solution. Besides, the specific capacitance of the MnO2-P3 electrode nearly has 98.2% retention after 2000 cycles, showing good long-term cycle stability. These findings show that the MnO2-P3 is a promising electrode material for supercapacitors.

  4. Synthesis and electrochemical properties of layered structure Li[Ni0.5Co0.25Mn0.25]O2 cathode material

    International Nuclear Information System (INIS)

    Prathibha, G.; Rosaiah, P.; Reddy, B. Purusottam; Ganesh, K. Sivajee; Hussain, O. M.

    2015-01-01

    Lithium ion (Li-ion) batteries are currently the energy source of choice for cell phones, laptops, and other mobile electronic devices due to their balance of high energy density with high power density compared to other electrochemical energy carriers. In the present study, mixed hydroxide method is used to prepare Li[Ni 0.5 Co 0.25 Mn 0.25 ]O 2 from the precursors and analyze qualitatively and studied the electrochemical properties. The XRD spectrum exhibited predominant (003) orientation at 2θ =18.39 o corresponding to hexagonal layered structure of R3m symmetry with evaluated lattice parameters are a= 2.84 Å, c= 14.43 Å. Raman measurements were performed to understand the microstructure and vibrational modes of the prepared sample. From the electrochemical (EC) studies an initial discharge capacity of about 140 mAhg −1 with good cyclic stability was observed for the prepared sample in the potential range 0.0 −1.0V in aqueous medium

  5. Electrochemical cell

    Science.gov (United States)

    Kaun, T.D.

    An improved secondary electrochemical cell is disclosed having a negative electrode of lithium aluminum, a positive electrode of iron sulfide, a molten electrolyte of lithium chloride and potassium chloride, and the combination that the fully charged theoretical capacity of the negative electrode is in the range of 0.5 to 1.0 that of the positive electrode. The cell thus is negative electrode limiting during discharge cycling. Preferably, the negative electrode contains therein, in the approximate range of 1 to 10 volume % of the electrode, an additive from the materials of graphitized carbon, aluminum-iron alloy, and/or magnesium oxide.

  6. Synthesis, characterization and electrochemical performance of graphene decorated with 1D NiMoO4.nH2O nanorods

    Science.gov (United States)

    Ghosh, Debasis; Giri, Soumen; Das, Chapal Kumar

    2013-10-01

    One-dimensional NiMoO4.nH2O nanorods and their graphene based hybrid composite with good electrochemical properties have been synthesized by a cost effective hydrothermal procedure. The formation of the mixed metal oxide and the composite was confirmed by XRD, XPS and Raman analyses. The morphological characterizations were carried out using FESEM and TEM analyses. The materials were subjected to electrochemical characterization through cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) studies with 6 M KOH as the supporting electrolyte. For NiMoO4.nH2O, a maximum specific capacitance of 161 F g-1 was obtained at 5 A g-1 current density, accompanied with an energy density of 4.53 W h kg-1 at a steady power delivery rate of 1125 W kg-1. The high utility of the pseudocapacitive NiMoO4.nH2O was achieved in its graphene based composite, which exhibited a high specific capacitance of 367 F g-1 at 5 A g-1 current density and a high energy density of 10.32 W h kg-1 at a power density of 1125 W kg-1 accompanied with long term cyclic stability.One-dimensional NiMoO4.nH2O nanorods and their graphene based hybrid composite with good electrochemical properties have been synthesized by a cost effective hydrothermal procedure. The formation of the mixed metal oxide and the composite was confirmed by XRD, XPS and Raman analyses. The morphological characterizations were carried out using FESEM and TEM analyses. The materials were subjected to electrochemical characterization through cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) studies with 6 M KOH as the supporting electrolyte. For NiMoO4.nH2O, a maximum specific capacitance of 161 F g-1 was obtained at 5 A g-1 current density, accompanied with an energy density of 4.53 W h kg-1 at a steady power delivery rate of 1125 W kg-1. The high utility of the pseudocapacitive NiMoO4.nH2O was achieved in its graphene

  7. A New Type of Synthesis of 1,2,3-Thiadiazole and 1,2,3-Diazaphosphole Derivatives Via-Hurd-Mori Cyclization

    Directory of Open Access Journals (Sweden)

    Mona A. Hosny

    2012-01-01

    Full Text Available We present a short and efficient synthesis of the title compounds starting with cheap and readily available camphor and derivatives of acetophenone. The optimized sequence allows the large-scale preparation of this new type of synthesis in a few steps. New 1,2,3-thiadiazole and 1,2,3-diazaphosphole derivatives 11-20, were prepared from the ketones 1-5 via the corresponding semicarbazones 6-10. The Hurd-Mori and Lalezari methods were used, respectively, for the preparation of these 1,2,3-thiadiazole and 1,2,3-diazaphospholene derivatives. These derivatives exhibit anticancer effect due to their high potential biological activity.

  8. Facile synthesis of the necklace-like graphene oxide-multi-walled carbon nanotube nanohybrid and its application in electrochemical sensing of Azithromycin

    International Nuclear Information System (INIS)

    Zhang, Kaixin; Lu, Limin; Wen, Yangping; Xu, Jingkun; Duan, Xuemin; Zhang, Long; Hu, Dufen; Nie, Tao

    2013-01-01

    Graphical abstract: -- Highlights: •The necklace-like GO-MWCNTs nanohybrid was facilely synthesized by ultrasonication. •The nanocomposites can be effectively used for the detection of Azithromycin. •Low detection limit with wide linear range could be obtained. •The method was applied to determine Azi in real samples. -- Abstract: A novel electrochemical platform was designed for the determination of Azithromycin (Azi), a widely used macrolide antibiotic, by combining the hydrophilic properties of graphene oxide (GO) and the excellent electronic and antifouling properties of multi-walled carbon nanotubes (MWCNTs). Stable MWCNTs aqueous dispersion has been prepared using GO nano-sheets as surfactant and the obtained GO-MWCNTs nanohybrid was characterized by UV–vis spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, transmission electron microscopy and electrochemical impedance spectroscopy, which confirmed that GO nano-sheets were attached onto the wall of MWCNTs to form a necklace-like structure. Electrochemical results obviously reveal that the oxidation peak currents of Azi obtained at the GC electrode modified with GO-MWCNTs hybrid are much higher than those at the MWCNTs/GC, GO/GC and bare GC electrodes. Under optimized conditions, the anodic peak current was linear to the concentration of Azi in the range from 0.1 to 10 μM with the detection limit of 0.07 μM. To further validate its possible application, the proposed method was successfully used for the determination of Azi in pharmaceutical formulations with satisfactory results

  9. Facile hydrothermal synthesis of polyhedral Fe3O4 nanocrystals, influencing factors and application in the electrochemical detection of H2O2

    International Nuclear Information System (INIS)

    Yuan Kefeng; Ni Yonghong; Zhang Li

    2012-01-01

    Highlights: ► Fe 3 O 4 polyhedra had been successfully synthesized by a facile hydrothermal technology. ► The as-obtained product exhibited the room-temperature ferrimagnetic property. ► The final product could be prepared into an electrochemical sensor for the detection of H 2 O 2 . - Abstract: Polyhedral Fe 3 O 4 nanocrystals have been successfully synthesized by a facile hydrothermal technique, employing FeSO 4 ·7H 2 O, N 2 H 4 and NH 3 ·H 2 O as the reactants without the assistance of any surfactant. The phase of the as-obtained Fe 3 O 4 was characterized by X-ray powder diffraction (XRD) and further proved by Rietveld refinement of XRD data. Energy dispersive spectrometry (EDS) and scanning electron microscopy (SEM) were used for the composition and morphology analyses of the final product. Some factors influencing the formation of polyhedral Fe 3 O 4 nanocrystals were systematically investigated, including the reaction temperature and time, and the original volume ratio of NH 3 ·H 2 O/N 2 H 4 ·H 2 O. It was found that the as-prepared Fe 3 O 4 polyhedra exhibited a good electrochemical property in 0.1 M phosphate buffer solution (PBS) with pH 7.0 and could be prepared into an electrochemical sensor for the detection of H 2 O 2 . The linear response range of the sensor was 10.0 × 10 −6 to 140.0 × 10 −6 M and a sensitivity was 11.05 μA/mM. Furthermore, the room-temperature magnetic property of the product was also investigated.

  10. Soft-template-synthesis of hollow CuO/Co{sub 3}O{sub 4} composites for pseudo-capacitive electrode: A synergetic effect on electrochemical performance

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Kuaibing, E-mail: wangkb@njau.edu.cn [Department of Chemistry, College of Science, Nanjing Agricultural University, Nanjing 210095 (China); State Key Laboratory of Coordination Chemistry, Coordination Chemistry Institute, Nanjing University, Nanjing 210093 (China); Lv, Bo; Wu, Hua; Luo, Xuefei; Xu, Jiangyan [Department of Chemistry, College of Science, Nanjing Agricultural University, Nanjing 210095 (China); Geng, Zhirong [State Key Laboratory of Coordination Chemistry, Coordination Chemistry Institute, Nanjing University, Nanjing 210093 (China)

    2016-12-15

    Hollow CuO/Co{sub 3}O{sub 4} hybrids, which inherited from its coordination polymer precursor consisting of sheets layer and nanoparticles layer composites, were synthesized and characterized by SEM, EDX, XRD and XPS. To assess its electrochemical capacitive performances, cyclic voltammetry, galvanostatic charging-discharging measurements and A.C. impedance tests were performed successively. The CuO/Co{sub 3}O{sub 4} hybrids had higher capacitance and lower charge transfer resistance than bare Co{sub 3}O{sub 4} nanostructures, revealing that it provided a protection layer and produced a synergistic effect due to the existence of CuO layer. The distinct synergistic effect could be further confirmed by endurance cycling tests. The capacitance of the CuO/Co{sub 3}O{sub 4} hybrids was 111% retained after 500 cycles at a charging rate of 1.0 A g{sup −1} and remained an intense growth trend after 2000 cycles at scan rate of 200 mV s{sup −1}. - Graphical abstract: Hollow CuO/Co{sub 3}O{sub 4} hybrids are synthesized and display a peculiar synergetic effect on the resulting performances, which can further be evaluated and confirmed by series of electrochemical measurements. - Highlights: • Hollow CuO/Co{sub 3}O{sub 4} hybrids are synthesized from bimetallic-Schiff base polymer precursors. • The capacitance of the CuO/Co{sub 3}O{sub 4} hybrids keeps a growth tendency after 2000 cycles. • A synergetic effect is found for the hybrids in electrochemical energy storage process.

  11. Synthesis and electrochemical properties of Li{sub 2}ZnTi{sub 3}O{sub 8} fibers as an anode material for lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Wang Li; Wu Lijuan; Li Zhaohui; Lei Gangtie [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Hunan 411105 (China); Xiao Qizhen, E-mail: qizhenxiao2004@yahoo.com.cn [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Hunan 411105 (China); College of Civil Engineering and Mechanics, Xiangtan University, Hunan 411105 (China); Zhang Ping [College of Civil Engineering and Mechanics, Xiangtan University, Hunan 411105 (China)

    2011-06-01

    Highlights: > A simple electrospinning method has been developed to fabricate Li{sub 2}ZnTi{sub 3}O{sub 8} fibers. > Li{sub 2}ZnTi{sub 3}O{sub 8} fibers as anode material for lithium-ion batteries. > A stable and reversible capacity of over 227 mAh g{sup -1} is achieved at a rate of 0.1 C. > Li{sub 2}ZnTi{sub 3}O{sub 8} anode exhibits good cycle performance and high rate capability. - Abstract: Li{sub 2}ZnTi{sub 3}O{sub 8} fibers are synthesized by thermally treating electrospun Zn(CH{sub 3}COO){sub 2}/LiOAc/TBT/PVP fibers and utilized as an energy storage material for rechargeable lithium-ion batteries. The material is characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and thermal analysis. Scanning electron microscopy results show that the Li{sub 2}ZnTi{sub 3}O{sub 8} fibers have an average diameter of 200 nm. Electrochemical properties of the material are evaluated using cyclic voltammetry, galvanostatic cycling and electrochemical impedance spectroscopy. The results show that as-prepared Li{sub 2}ZnTi{sub 3}O{sub 8} has a high specific discharge capacity of 227.6 mAh g{sup -1} at the 2nd cycle. Its electrochemical performance at subsequent cycles shows good cycling capacity and rate capability. The obtained results thus strongly support that the electrospinning method is an effective method to prepare Li{sub 2}ZnTi{sub 3}O{sub 8} anode material with higher capacity and rate capability.

  12. Facile synthesis of the necklace-like graphene oxide-multi-walled carbon nanotube nanohybrid and its application in electrochemical sensing of Azithromycin

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Kaixin [Jiangxi Key Laboratory of Organic Chemistry, Jiangxi Science and Technology Normal University, Nanchang 330013 (China); Lu, Limin; Wen, Yangping [Jiangxi Key Laboratory of Organic Chemistry, Jiangxi Science and Technology Normal University, Nanchang 330013 (China); College of Science, Jiangxi Agricultural University, Nanchang 330045 (China); Xu, Jingkun, E-mail: xujingkun@tsinghua.org.cn [Jiangxi Key Laboratory of Organic Chemistry, Jiangxi Science and Technology Normal University, Nanchang 330013 (China); Duan, Xuemin; Zhang, Long; Hu, Dufen [Jiangxi Key Laboratory of Organic Chemistry, Jiangxi Science and Technology Normal University, Nanchang 330013 (China); Nie, Tao [Jiangxi Key Laboratory of Organic Chemistry, Jiangxi Science and Technology Normal University, Nanchang 330013 (China); College of Science, Jiangxi Agricultural University, Nanchang 330045 (China)

    2013-07-17

    Graphical abstract: -- Highlights: •The necklace-like GO-MWCNTs nanohybrid was facilely synthesized by ultrasonication. •The nanocomposites can be effectively used for the detection of Azithromycin. •Low detection limit with wide linear range could be obtained. •The method was applied to determine Azi in real samples. -- Abstract: A novel electrochemical platform was designed for the determination of Azithromycin (Azi), a widely used macrolide antibiotic, by combining the hydrophilic properties of graphene oxide (GO) and the excellent electronic and antifouling properties of multi-walled carbon nanotubes (MWCNTs). Stable MWCNTs aqueous dispersion has been prepared using GO nano-sheets as surfactant and the obtained GO-MWCNTs nanohybrid was characterized by UV–vis spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, transmission electron microscopy and electrochemical impedance spectroscopy, which confirmed that GO nano-sheets were attached onto the wall of MWCNTs to form a necklace-like structure. Electrochemical results obviously reveal that the oxidation peak currents of Azi obtained at the GC electrode modified with GO-MWCNTs hybrid are much higher than those at the MWCNTs/GC, GO/GC and bare GC electrodes. Under optimized conditions, the anodic peak current was linear to the concentration of Azi in the range from 0.1 to 10 μM with the detection limit of 0.07 μM. To further validate its possible application, the proposed method was successfully used for the determination of Azi in pharmaceutical formulations with satisfactory results.

  13. Synthesis of One Dimensional Li2MoO4 Nanostructures and Their Electrochemical Performance as Anode Materials for Lithium-ion Batteries

    International Nuclear Information System (INIS)

    Liu, Xudong; Zhao, Yanming; Dong, Youzhong; Fan, Qinghua; Kuang, Quan; Liang, Zhiyong; Lin, Xinghao; Han, Wei; Li, Qidong; Wen, Mingming

    2015-01-01

    Highlights: • One dimensional Li 2 MoO 4 nanostructures including nanorods and nanotubes have been successfully fabricated via a simple sol-gel method firstly. • Possible crystal formation mechanisms are proposed for these one dimensional Li 2 MoO 4 nanostructures. • These one dimensional Li 2 MoO 4 nanostructure electrode materials present outstanding rate abilities and cycle capabilities in electrochemical performance compared to the carbon-free powder sample when evaluated as anode materials for Lithium-ion batteries. • The carbon-coated Li 2 MoO 4 nanotube electrode improves the charging/discharging capacities of graphite even after applying 60 cycles at very high current density. - Abstract: One dimensional Li 2 MoO 4 nanostructures including nanorods and nanotubes have been successfully fabricated via a simple sol-gel method adding Li 2 CO 3 and MoO 3 powders into distilled water with citric acid as an assistant agent and carbon source. Our experimental results show that the formation of the one dimensional nanostructure morphology is evaporation and crystallization process with self-adjusting into a rod-like hexagonal cross-section structure, while the citric acid played an important role during the formation of Li 2 MoO 4 nanotubes under the acidic environment by capping, stabilizing the {1010} facet of Li 2 MoO 4 structure and controlling the concentration of H + (pH value) of the aqueous solution. Finally, basic electrochemical performance of these one dimensional Li 2 MoO 4 nanostructures including nanorods and nanotubes evaluated as anode materials for lithium-ion batteries (LIBs) are discussed, for comparison, the properties of carbon-free powder sample synthesized by solid-state reaction are also displayed. Experimental results show that different morphology and carbon-coating on the surface have an important influence on electrochemical performance

  14. Synthesis and electrochemical properties of tin-doped MoS{sub 2} (Sn/MoS{sub 2}) composites for lithium ion battery applications

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Lin; Min, Feixia; Luo, Zhaohui; Wang, Shiquan, E-mail: wsqhao@126.com [Hubei University, Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Ministry-of-Education Key Laboratory for Synthesis and Applications of Organic Functional Molecules (China); Teng, Fei [Nanjing University of Information Science and Technology, Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control (AEMPC), School of Environmental Sciences and Engineering (China); Li, Guohua [Zhejiang University of Technology, School of Chemical Engineering and Materials Science (China); Feng, Chuanqi [Hubei University, Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Ministry-of-Education Key Laboratory for Synthesis and Applications of Organic Functional Molecules (China)

    2016-12-15

    SnO{sub 2}-MoO{sub 3} composites were synthesized by using (NH{sub 4}){sub 6}Mo{sub 7}O{sub 24}·4H{sub 2}O and SnCl{sub 2}·2H{sub 2}O as raw materials through a simple solvothermal method followed by pyrolysis. Tin-doped MoS{sub 2} (Sn/MoS{sub 2}) flowers have been synthesized by a solvothermal method followed with annealing in Ar(H{sub 2}) atmosphere, with SnO{sub 2}-MoO{sub 3}, thioacetamide (TAA), and urea as starting materials. The doping and the content of Sn-doping play crucial roles in the morphology and electrochemical performance of the MoS{sub 2}. As anode materials for lithium ion battery (LIB), all Sn/MoS{sub 2} composites exhibit both higher reversible capacity and better cycling performance at current density of 200 mA g{sup −1}, compared with MoS{sub 2} without Sn doping. The achieved discharge capacity for Sn/MoS{sub 2} composites is above 1000 mAh g{sup −1} after 100 cycles with nearly 100% coulombic efficiency. The doping of metal Sn in MoS{sub 2} can improve the conductivity of MoS{sub 2} and significantly enhance its electrochemical properties. The good electrochemical performance suggests that the Sn/MoS{sub 2} composite could be a promising candidate as a novel anode material for LIB application. Our present work provides a new approach to the fabrication of anode materials for LIB applications.

  15. Facile chemical synthesis of nanoporous layered δ-MnO{sub 2} thin film for high-performance flexible electrochemical capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Yu; Wang, Jun; Jiang, Xionghua; Zheng, Yanfeng [The Key Laboratory of Low-Carbon Chemistry and Energy Conservation of Guangdong Province, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Chen, Zhenxing, E-mail: chenzx65@mail.sysu.edu.cn [The Key Laboratory of Low-Carbon Chemistry and Energy Conservation of Guangdong Province, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275 (China)

    2013-04-15

    Layered δ-MnO{sub 2} thin films with a three-dimensional nanostructure are successfully fabricated on stainless steel foil substrates for flexible electrochemical capacitors by a facile and effective chemical bath deposition technology from ethanol and potassium permanganate solution at 15 °C. The as-prepared thin films display nanoporous morphology and a water contact angle of 20°. Energy-dispersive X-ray spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy analyses reveal that the thin films are composed of δ-MnO{sub 2}. Electrochemical data demonstrate that the δ-MnO{sub 2} thin film electrodes can deliver a high special capacitance of 447 F/g at 2 mV/s, and provide a good capacitance retention ratio of 87% after 1000 continuous cycles at 10 mV/s in 0.5 M Na{sub 2}SO{sub 4}. Compressive and tensile bending tests show that the as-prepared electrodes can steadily work over a wide range of applied curvatures between −2.5 cm{sup −1} (tension) and 2.5 cm{sup −1} (compression). Only a small decrease in special capacitance (0.9% at a curvature of 2.5 cm{sup −1} under compressive strain, or 1.2% at a curvature of −2.5 cm{sup −1} under tensile strain) is observed even after bending for 200 cycles, indicating the excellent mechanical flexibility and electrochemical stability of the δ-MnO{sub 2} thin film electrodes.

  16. Fast and low-cost synthesis of 1D ZnO–TiO{sub 2} core–shell nanoarrays: Characterization and enhanced photo-electrochemical performance for water splitting

    Energy Technology Data Exchange (ETDEWEB)

    Hernández, Simelys, E-mail: simelys.hernandez@iit.it [Center for Space Human Robotics (IIT-POLITO), Istituto Italiano di Tecnologia, Corso Trento 21, 10129 Torino (Italy); Cauda, Valentina; Hidalgo, Diana; Farías Rivera, Vivian; Manfredi, Diego; Chiodoni, Angelica [Center for Space Human Robotics (IIT-POLITO), Istituto Italiano di Tecnologia, Corso Trento 21, 10129 Torino (Italy); Pirri, Fabrizio C. [Center for Space Human Robotics (IIT-POLITO), Istituto Italiano di Tecnologia, Corso Trento 21, 10129 Torino (Italy); Applied Science and Technology Department, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy)

    2014-12-05

    Highlights: • Simple, fast and low-cost synthesis of 1-D ZnO–TiO{sub 2} core–shell heterostructures. • ZnO NWs completely covered with a shell of anatase TiO{sub 2} nanocrystals in only 3 min. • The TiO{sub 2} shell thickness depends on the impregnation time in the titania synthesis bath. • 2-fold enhancement of photo-electrochemical activity and better stability of ZnONWs. • Forty- times higher photocurrent densities than TiO{sub 2} nanoparticles film. - Abstract: We report on a simple, fast and low-cost synthesis procedure for the complete covering of zinc oxide (ZnO) 1D nanostructures with a protective shell of titania (TiO{sub 2}) nanoparticles. ZnO nanowires (NWs) were grown on transparent F-doped Tin Oxide (FTO) conductive layer on glass by seed layer-assisted hydrothermal route in aqueous media, while the titania shell was deposited on the ZnO NWs through an in situ non-acid sol–gel synthesis. The nanowires impregnation time in the titania sol was varied from 3 to 10 min. The resulting core–shell ZnO–TiO{sub 2} structures were characterized by different techniques, including Scanning and Transmission Electron Microscopy, X-ray diffraction and UV–Vis spectroscopy, confirming the uniform coverage of the wurzite ZnO NWs with anatase TiO{sub 2} nanoparticles (NPs), with a shell thickness dependent on the impregnation time in the titania synthesis bath. Photoelectrochemical (PEC) tests of the ZnO–TiO{sub 2} material, used as anode for the water splitting reaction, confirmed the formation of the heterojunction by the enhanced photocurrent densities, reaching values of about 0.7 mA/cm{sup 2} under simulated solar light (AM1.5G, 100mW/cm{sup 2}). The core–shell photo-anodes performance was about twice and forty- times better than the ones with a film of equivalent thickness of bare ZnO NWs and TiO{sub 2} NPs, respectively. Steady-state measures of the photocurrent over the time and FESEM analysis confirmed that this procedure could be

  17. Electrochemical attosyringe.

    Science.gov (United States)

    Laforge, François O; Carpino, James; Rotenberg, Susan A; Mirkin, Michael V

    2007-07-17

    The ability to manipulate ultrasmall volumes of liquids is essential in such diverse fields as cell biology, microfluidics, capillary chromatography, and nanolithography. In cell biology, it is often necessary to inject material of high molecular weight (e.g., DNA, proteins) into living cells because their membranes are impermeable to such molecules. All techniques currently used for microinjection are plagued by two common problems: the relatively large injector size and volume of injected fluid, and poor control of the amount of injected material. Here we demonstrate the possibility of electrochemical control of the fluid motion that allows one to sample and dispense attoliter-to-picoliter (10(-18) to 10(-12) liter) volumes of either aqueous or nonaqueous solutions. By changing the voltage applied across the liquid/liquid interface, one can produce a sufficient force to draw solution inside a nanopipette and then inject it into an immobilized biological cell. A high success rate was achieved in injections of fluorescent dyes into cultured human breast cells. The injection of femtoliter-range volumes can be monitored by video microscopy, and current/resistance-based approaches can be used to control injections from very small pipettes. Other potential applications of the electrochemical syringe include fluid dispensing in nanolithography and pumping in microfluidic systems.

  18. Synthesis and Electrochemical Performance of Graphene Wrapped SnxTi1−xO2 Nanoparticles as an Anode Material for Li-Ion Batteries

    Directory of Open Access Journals (Sweden)

    Xing Xin

    2015-01-01

    Full Text Available Ever-growing development of Li-ion battery has urged the exploitation of new materials as electrodes. Here, SnxTi1-xO2 solid-solution nanomaterials were prepared by aqueous solution method. The morphology, structures, and electrochemical performance of SnxTi1-xO2 nanoparticles were systematically investigated. The results indicate that Ti atom can replace the Sn atom to enter the lattice of SnO2 to form substitutional solid-solution compounds. The capacity of the solid solution decreases while the stability is improved with the increasing of the Ti content. Solid solution with x of 0.7 exhibits the optimal electrochemical performance. The Sn0.7Ti0.3O2 was further modified by highly conductive graphene to enhance its relatively low electrical conductivity. The Sn0.7Ti0.3O2/graphene composite exhibits much improved rate performance, indicating that the SnxTi1-xO2 solid solution can be used as a potential anode material for Li-ion batteries.

  19. Synthesis, pH dependent photometric and electrochemical investigation, redox mechanism and biological applications of novel Schiff base and its metallic derivatives

    Science.gov (United States)

    Rauf, Abdur; Shah, Afzal; Khan, Abdul Aziz; Shah, Aamir Hassan; Abbasi, Rashda; Qureshi, Irfan Zia; Ali, Saqib

    2017-04-01

    A novel Schiff base, 1-((2, 4-dimethylphenylimino)methyl)naphthalen-2-ol abbreviated as (HL) and its four metallic complexes were synthesized and confirmed by 1H and 13C NMR, FTIR, TGA and UV-Visible spectroscopy. Schiff base was also characterized by X-ray analysis. The photometric and electrochemical responses of all the synthesized compounds were investigated in a wide pH range. Structures of the compounds were optimized computationally for the evaluation of different physico-chemical parameters. On the basis of electrochemical results the redox mechanistic pathways of the compounds were proposed. The cytotoxicity analysis on Hela cells revealed that HL and its complexes inhibit cell growth as revealed from their IC50 values (HL):106.7 μM, (L2VO): 40.66 μM, (L2Sn): 5.92 μM, (L2Zn): 42.82 and (L2Co): 107.68 μM. The compounds were tested for anti-diabetic, triglyceride, cholesterol, anti-microbial, anti-fungal and enzyme inhibition activities. The results revealed that HL and its complexes are promising new therapeutic options as these compounds exhibit strong activity against cancer cells, diabetics, fungal and microbial inhibition.

  20. Synthesis and characterization of NiCo{sub 2}O{sub 4} nanoplates as efficient electrode materials for electrochemical supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Taehyun [Nanomaterials and System Lab, Department of Mechatronics Engineering, Engineering College, Jeju National University, Jeju 690-756 (Korea, Republic of); Ramadoss, Ananthakumar [Nanomaterials and System Lab, Faculty of Applied Energy System, Science and Engineering College, Jeju National University, Jeju 690-756 (Korea, Republic of); Saravanakumar, Balasubramaniam; Veerasubramani, Ganesh Kumar [Nanomaterials and System Lab, Department of Mechatronics Engineering, Engineering College, Jeju National University, Jeju 690-756 (Korea, Republic of); Kim, Sang Jae, E-mail: kimsangj@jejunu.ac.kr [Nanomaterials and System Lab, Department of Mechatronics Engineering, Engineering College, Jeju National University, Jeju 690-756 (Korea, Republic of); Nanomaterials and System Lab, Faculty of Applied Energy System, Science and Engineering College, Jeju National University, Jeju 690-756 (Korea, Republic of)

    2016-05-01

    Highlights: • NiCo{sub 2}O{sub 4} nanoplates were synthesized through a facile approach. • The NiCo{sub 2}O{sub 4} nanoplates electrode material exhibit a specific capacitance of 332 F g{sup −1} at 5 mV s{sup −1}. • The fabricated NiCo{sub 2}O{sub 4} electrode reveals 86% retention of initial capacitance after 2000 cycles. - Abstract: In the present work, NiCo{sub 2}O{sub 4} nanoplates were prepared by a facile, low temperature, hydrothermal method, followed by thermal annealing and used supercapacitor applications. The physico-chemical characterization of as-prepared materials were investigated by means of X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FT-IR) and field emission scanning electron microscopy (FE-SEM). The electrochemical measurements demonstrate that the NiCo{sub 2}O{sub 4} nanoplates electrode (NC-5) exhibits a high specific capacitance of 332 F g{sup −1} at a scan rate of 5 mV s{sup −1} and also retained about 86% of the initial specific capacitance value even after 2000 cycles at a current density of 2.5 A g{sup −1}. These results suggest that the fabricated electrode material has huge potential as a novel electrode material for electrochemical capacitors.

  1. Synthesis and electrochemical performance of multi-walled carbon nanotube/polyaniline/MnO{sub 2} ternary coaxial nanostructures for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Li, Qiang [School of Electronic Science and Applied Physics, Hefei University of Technology, Hefei, Anhui 230009 (China); School of Materials Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009 (China); Liu, Jianhua; Zou, Jianhua; Chunder, Anindarupa; Zhai, Lei [NanoScience Technology Center and Department of Chemistry, University of Central Florida, 12424 Research Parkway, Suite 400, Orlando, FL 32826 (United States); Chen, Yiqing [School of Materials Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009 (China)

    2011-01-01

    Multi-walled carbon nanotube (MWCNT)/polyaniline (PANI)/MnO{sub 2} (MPM) ternary coaxial structures are fabricated as supercapacitor electrodes via a simple wet chemical method. The electrostatic interaction between negative poly(4-styrenesulfonic acid) (PSS) molecules and positive Mn{sup 2+} ions causes the generation of MnO{sub 2} nanostructures on MWCNT surfaces while the introduction of PANI layers with appropriate thickness on MWCNT surfaces facilitates the formation of MWCNT/PANI/MnO{sub 2} ternary coaxial structures. The thickness of PANI coatings is controlled by tuning the aniline/MWCNT ratio. The effect of PANI thickness on the subsequent MnO{sub 2} nanoflakes attachment onto MWCNTs, and the MPM structures is investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and field-emission scanning electron microscopy (FESEM). The results suggest that appropriate thickness of PANI layers is important for building MPM ternary coaxial structures without the agglomeration of MnO{sub 2} nanoflakes. The MPM ternary coaxial structures provide large interaction area between the MnO{sub 2} nanoflakes and electrolyte, and improve the electrochemical utilization of the hydrous MnO{sub 2}, and decrease the contact resistance between MnO{sub 2} and PANI layer coated MWCNTs, leading to intriguing electrochemical properties for the applications in supercapacitors such as a specific capacitance of 330 Fg{sup -1} and good cycle stability. (author)

  2. Soft template synthesis of mesoporous Co3O4/RuO2.xH2O composites for electrochemical capacitors

    International Nuclear Information System (INIS)

    Liu Yang; Zhao Weiwei; Zhang Xiaogang

    2008-01-01

    Co 3 O 4 /RuO 2 .xH 2 O composites with various Ru content (molar content of Ru = 5%, 10%, 20%, 50%) were synthesized by one-step co-precipitation method. The precursors were prepared via adjusting pH of the mixed aqueous solutions of Co(NO 3 ) 2 .6H 2 O and RuCl 3 .0.5H 2 O by using Pluronic123 as a soft template. For the composite with molar ratio of Co:Ru = 1:1 annealed at 200 deg. C, Brunauer-Emmet-Teller (BET) results indicated that the composite showed mesoporous structure, and the specific surface area of the composite was as high as 107 m 2 g -1 . The electrochemical performances of these composites were measured in 1 M KOH electrolyte. Compared with the composite prepared without template, the composite with P123 exhibited a higher specific capacitance. When the molar content of Ru was rising, the specific capacitance of the composites increased significantly. It was also observed that the crystalline structures as well as the electrochemical activities were strongly dependent on the annealing temperature. A capacitance of 642 F/g was obtained for the composite (Co:Ru = 1:1) annealed at 150 deg. C. Meanwhile, the composites also exhibited good cycle stability. Besides, the morphologies and textural characteristic of the samples were also investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM)

  3. Electrochemical synthesis of polyaniline in the presence of poly(amidosulfonic acid)s with different rigidity of polymer backbone and characterization of the films obtained

    International Nuclear Information System (INIS)

    Nekrasov, A.A.; Gribkova, O.L.; Eremina, T.V.; Isakova, A.A.; Ivanov, V.F.; Tverskoj, V.A.; Vannikov, A.V.

    2008-01-01

    We have studied electrochemical matrix polymerization of aniline in the presence of poly(amidosulfonic acid)s of different nature: poly(2-acrylamido-2-methyl-1-propanosulfonic acid) (PAMPSA, flexible backbone); poly(p,p'-(2,2'-disulfoacid)-diphenylene-iso-phthalamid) (i-PASA, semi-rigid backbone); poly(p,p'-(2,2'-disulfoacid)-diphelylene-tere-phthalamid) (t-PASA, rigid backbone). Also, we have investigated spectral and electrochemical properties of the films obtained, as well as their surface morphology. The matrix polymerization results in the formation of interpolymer complexes of polyaniline (PANI) and the above-cited polyacids. The acceleration of aniline electropolymerizatio