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Sample records for electrochemically synthesized tio2

  1. Electrical characterization of TiO2 nanotubes synthesized through electrochemical anodizing method

    Science.gov (United States)

    Manescu Paltanea, Veronica; Paltanea, Gheorghe; Popovici, Dorina; Jiga, Gabriel

    2016-05-01

    In the present paper, the electrochemical anodizing method was used for the obtaining of TiO2 nanotube layers, developed on titanium surface. Self-organized titanium nanotubes were obtained when an aqueous solution of 49.5 wt % H2O - 49.5 wt % glycerol - 1 wt % HF was used as electrolyte, the anodizing time being equal to 8 hours and the applied voltage to 25 V. Scanning electron microscopy shows that the one-dimensional nanostructure has a tubular configuration with an inner diameter of approximately 60 nm and an outer diameter of approximately 100 nm. The electrical properties of these materials were analyzed through dielectric spectroscopy method.

  2. Electrochemically synthesized visible light absorbing vertically aligned N-doped TiO2 nanotube array films

    International Nuclear Information System (INIS)

    Antony, Rajini P.; Mathews, Tom; Ajikumar, P.K.; Krishna, D. Nandagopala; Dash, S.; Tyagi, A.K.

    2012-01-01

    Graphical abstract: Display Omitted Highlights: ► Single step electrochemical synthesis of N-doped TiO 2 nanotube array films. ► Effective substitutional N-doping achieved. ► Different N-concentrations were achieved by varying the N-precursor concentration in the electrolyte. ► Visible light absorption observed at high N-doping. -- Abstract: Visible light absorbing vertically aligned N-doped anatase nanotube array thin films were synthesized by anodizing Ti foils in ethylene glycol + NH 4 F + water mixture containing urea as nitrogen source. Different nitrogen concentrations were achieved by varying the urea content in the electrolyte. The structure, morphology, composition and optical band gap of the nanotube arrays were determined by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy (XPS) and diffuse reflectance spectroscopy, respectively. The substitution of O 2− ions by N 3− ions in the anion sublattice as well as the formulae of the doped samples was confirmed from the results of XPS. The optical band gap of the nanotube arrays was found to decrease with N-concentration. The sample with the highest concentration corresponding to the formula TiO 1.83 N 0.14 showed two regions in the Tauc's plot indicating the presence of interband states.

  3. An electrochemical aptasensor based on TiO2/MWCNT and a novel synthesized Schiff base nanocomposite for the ultrasensitive detection of thrombin.

    Science.gov (United States)

    Heydari-Bafrooei, Esmaeil; Amini, Maryam; Ardakani, Mehdi Hatefi

    2016-11-15

    A sensitive aptasensor based on a robust nanocomposite of titanium dioxide nanoparticles, multiwalled carbon nanotubes (MWCNT), chitosan and a novel synthesized Schiff base (SB) (TiO2/MWCNT/CHIT/SB) on the surface of a glassy carbon electrode (GCE) was developed for thrombin detection. The resultant nanocomposite can provide a large surface area, excellent electrocatalytic activity, and high stability, which would improve immobilization sites for biological molecules, allow remarkable amplification of the electrochemical signal and contribute to improved sensitivity. Thrombin aptamers were simply immobilized onto the TiO2-MWCNT/CHIT-SB nanocomposite matrix through simple π - π stacking and electrostatic interactions between CHIT/SB and aptamer strands. The electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to analyze the surface characterization of unmodified GCE and TiO2-MWCNT/CHIT-SB modified GCE, and also the interaction between aptamer and thrombin. In the presence of thrombin, the aptamer on the adsorbent layer captures the target on the electrode interface, which makes a barrier for electrons and inhibits electron transfer, thereby resulting in decreased DPV and increased impedance signals of the TiO2-MWCNT/CHIT-SB modified GCE. Furthermore, the proposed aptasensor has a very low LOD of 1.0fmolL(-1) thrombin within the detection range of 0.00005-10nmolL(-1). The aptasensor also presents high specificity and reproducibility for thrombin, which is unaffected by the coexistence of other proteins. Clinical application was performed with analysis of the thrombin levels in blood and CSF samples obtained from patients with MS, Parkinson, Epilepsy and Polyneuropathy using both the aptasensor and commercial ELISA kit. The results revealed the proposed system to be a promising candidate for clinical analysis of thrombin. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Microwave synthesized nanostructured TiO2-activated carbon composite electrodes for supercapacitor

    International Nuclear Information System (INIS)

    Selvakumar, M.; Bhat, D. Krishna

    2012-01-01

    Highlights: ► Nanostructure TiO 2 has been prepared by a microwave assisted synthesis method. ► Microwave irradiation was varied with time duration on the formation of nanoparticles. ► TiO 2 -activate carbon show very good specific capacitance for supercapacitor. ► Electrochemical properties were studied on electroanalytical techniques. - Abstract: Electrochemical properties of a supercapacitor based on nanocomposite electrodes of activated carbon with TiO 2 nano particles synthesized by a microwave method have been determined. The TiO 2 /activated carbon nanocomposite electrode with a composition of 1:3 showed a specific capacitance 92 Fg −1 . The specific capacitance of the electrode decreased with increase in titanium dioxide content. The p/p symmetrical supercapacitor fabricated with TiO 2 /activated carbon composite electrodes showed a specific capacitance of 122 Fg −1 . The electrochemical behavior of the neat TiO 2 nanoparticles has also been studied for comparison purpose. The galvanostatic charge–discharge test of the fabricated supercapacitor showed that the device has good coulombic efficiency and cycle life. The specific capacitance of the supercapacitor was stable up to 5000 cycles at current densities of 2, 4, 6 and 7 mA cm −2 .

  5. 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

  6. Electrochemical properties of TiO2 encapsulated ZnO nanorod aggregates dye sensitized solar cells

    International Nuclear Information System (INIS)

    Justin Raj, C.; Karthick, S.N.; Dennyson Savariraj, A.; Hemalatha, K.V.; Park, Song-Ki; Kim, Hee-Je; Prabakar, K.

    2012-01-01

    Highlights: ► ZnO nanorod aggregates were synthesized by simple co-precipitation technique. ► TiO 2 encapsulated ZnO nanorod aggregates photoanode was used for the DSSC. ► TiO 2 encapsulated ZnO nanorod aggregates shows an enhanced efficiency. ► The electron recombination and transport properties were studied using EIS method. - Abstract: Dye sensitized solar cells based on TiO 2 encapsulated ZnO nanorod (NR) aggregates were fabricated and electrochemical performance was analyzed using impedance spectroscopy as a function of forward bias voltage. Charge transfer properties such as electron life time (τ n ), electron diffusion coefficient (D n ) and electron diffusion length (L n ) were calculated in order to ensure the influence of TiO 2 layer over the ZnO NR aggregates. It is found that the short circuit current density (Jsc = 5.8 mA cm −2 ), open circuit potential (V oc = 0.743 V), fill factor (FF = 0.57) and conversion efficiency are significantly improved by the introduction of TiO 2 layer over ZnO photoanode. A power conversion efficiency of about 2.48% has been achieved for TiO 2 /ZnO cell, which is higher than that of bare ZnO NR aggregate based cells (1.73%). The formation of an inherent energy barrier between TiO 2 and ZnO films and the passivation of surface traps on the ZnO film caused by the introduction of TiO 2 layer increase the dye absorption and favor the electron transport which may be responsible for the enhanced performance of TiO 2 /ZnO cell.

  7. Microporous TiO2-WO3/TiO2 films with visible-light photocatalytic activity synthesized by micro arc oxidation and DC magnetron sputtering

    International Nuclear Information System (INIS)

    Wu, Kee-Rong; Hung, Chung-Hsuang; Yeh, Chung-Wei; Wu, Jiing-Kae

    2012-01-01

    Highlights: ► A simple MAO is used to prepare porous WO 3 /TiO 2 layer on Ti sheet as a visible-light enabled catalyst. ► The photocatalytic activity of the WO 3 /TiO 2 is enhanced by sputtering over an N,C-TiO 2 layer. ► This is ascribed to the synergetic effect of hybrid sample prepared by two-step method. - Abstract: This study reports the preparation of microporous TiO 2 -WO 3 /TiO 2 films with a high surface area using a two-step approach. A porous WO 3 /TiO 2 template was synthesized by oxidizing a titanium sheet using a micro arc oxidation (MAO) process. This sheet was subsequently overlaid with a visible light (Vis)-enabled TiO 2 (N,C-TiO 2 ) film, which was deposited by codoping nitrogen (N) and carbon (C) ions into a TiO 2 lattice using direct current magnetron sputtering. The resulting microporous TiO 2 -WO 3 /TiO 2 film with a 0.38-μm-thick N,C-TiO 2 top-layer exhibited high photocatalytic activity in methylene blue (MB) degradation among samples under ultraviolet (UV) and Vis irradiation. This is attributable to the synergetic effect of two-step preparation method, which provides a highly porous microstructure and the well-crystallized N,C-TiO 2 top-layer. This is because a higher surface area with high crystallinity favors the adsorption of more MB molecules and more photocatalytic active areas. Thus, the microporous TiO 2 -WO 3 /TiO 2 film has promising applications in the photocatalytic degradation of dye solution under UV and Vis irradiation. These results imply that the microporous WO 3 /TiO 2 can be used as a template of hybrid electrode because it enables rapid fabrication.

  8. Preparation and electrochemical property of TiO_2/Nano-graphite composite anode for electro-catalytic degradation of ceftriaxone sodium

    International Nuclear Information System (INIS)

    Guo, Xiaolei; Li, Dong; Wan, Jiafeng; Yu, Xiujuan

    2015-01-01

    Titanium dioxide/Nano-graphite (TiO_2/Nano-G) composite was synthesized by a sol-gel method and TiO_2/Nano-G electrode was prepared in hot-press approach. The composite was characterized by X-ray photoelectron spectroscopy (XPS), fourier transform infrared (FT-IR), scanning electrons microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The electrochemical performance of the TiO_2/Nano-G anode electrode was investigated through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The electro-catalytic performance was evaluated by the yield of ·OH radicals, degradation of methyl orange and ceftriaxone sodium. The results demonstrated that TiO_2 nanoparticles were dispersed on the surface and interlamination of the Nano-G uniformly, TiO_2/Nano-G electrode owned higher electro-catalytic oxidation activity and stability than Nano-G electrode. Degradation rate of ceftriaxone sodium within 120 min by TiO_2(40)/Nano-G electrode was 97.7%. And ·OH radicals given by TiO_2/Nano-G electrode was higher than that of Nano-G electrode and DSA (Ti/IrO_2-RuO_2) electrode. The excellent electro-catalytic performance could be ascribed to the admirable conductive property of the Nano-G and more production of ·OH offered by TiO_2(40)/Nano-G electrode.

  9. Polythiophene thin films electrochemically deposited on sol-gel based TiO2 for photovoltaic applications

    International Nuclear Information System (INIS)

    Valaski, R.; Yamamoto, N.A.D.; Canestraro, C.D.; Micaroni, L.; Mello, R.M.Q.; Quirino, W.G.; Legani, C.; Achete, C.A.; Roman, L.S.; Cremona, M.

    2010-01-01

    In this work, the influence of titanium dioxide (TiO 2 ) thin films on the efficiency of organic photovoltaic devices based on electrochemically synthesized polythiophene (PT) was investigated. TiO 2 films were produced by sol-gel methods with controlled thickness. The best TiO 2 annealing condition was determined through the investigation of the temperature influence on the electron charge mobility and resistivity in a range between 723 K and 923 K. The PT films were produced by chronoamperometric method in a 3-electrode cell under a controlled atmosphere. High quality PT films were produced onto 40 nm thick TiO 2 layer previously deposited onto fluorine doped tin oxide (FTO) substrate. The morphology of PT films grown on both substrates and its strong influence on the device performance and PT minimum thickness were also investigated. The maximum external quantum efficiency (IPCE) reached was 9% under monochromatic irradiation (λ = 610 nm; 1 W/m 2 ) that is three orders of magnitude higher than that presented by PT-homolayer devices with similar PT thickness. In addition, the open-circuit voltage (V oc ) was about 700 mV and the short-circuit current density (J sc ) was 0.03 A/m 2 (λ = 610 nm; 7 W/m 2 ). However, as for the PT-homolayer also the TiO 2 /PT based devices are characterized by antibatic response when illuminated through FTO. Finally, the Fill Factor (FF) of these devices is low (25%), indicating that the series resistance (R s ), which is strongly dependent of the PT thickness, is too large. This large R s value is compensated by TiO 2 /PT interface morphology and by FTO/TiO 2 and TiO 2 /PT interface phenomena producing preferential paths in which the internal electrical field is higher, improving the device efficiency.

  10. Electrochemical characteristics of porous TiO2 encapsulated silicon anode

    International Nuclear Information System (INIS)

    Jeon, Bup Ju; Lee, Joong Kee

    2011-01-01

    Graphical abstract: Cycling performances of the TiO 2 coated silicon anode at different catalyst pH values. Display Omitted Highlights: → TiO 2 coated silicon was used as the anode material for lithium batteries. → TiO 2 layer acted as a buffer layer for reducing the volume expansion. → Pore size distribution of TiO 2 coated silicon influenced discharge capacity. → Higher capacity retention was exhibited at pH 10.7. - Abstract: TiO 2 coated silicon, which was prepared by the modified sol-gel method, was employed as the anode material for lithium secondary batteries and the relationship between the diffusivity and electrochemical characteristics was investigated. The results showed that the physical properties of the samples, such as their diffusivity and pore size distribution, enhanced the cycling efficiency of the TiO 2 coated silicon, probably due to the reduction of the side reactions, which may be closely related to the pore size distribution of the TiO 2 coating layer. The pore size of the coating layer plays an important role in retarding the lithium ion diffusion. In the experimental range studied herein, higher capacity retention was exhibited for the TiO 2 coated silicon prepared at pH 10.7.

  11. Photocatalytic performance of pure anatase nanocrystallite TiO2 synthesized under low temperature hydrothermal conditions

    International Nuclear Information System (INIS)

    Sayilkan, Funda; Erdemoglu, Sema; Asiltuerk, Meltem; Akarsu, Murat; Sener, Sadiye; Sayilkan, Hikmet; Erdemoglu, Murat; Arpac, Ertugrul

    2006-01-01

    Photocatalytic performance of a hydrothermally synthesized pure anatase TiO 2 with 8 nm average crystallite size for decomposition of Reactive Red 141 was examined by investigating the effects of UV-light irradiation time, irradiation power, amount of TiO 2 and initial dye concentration. Change in the UV absorbance of the dye during irradiation was monitored. One wt.% TiO 2 in 30 mg/l Reactive Red 141 aqueous solution was found adequate for complete decolorization in 70 min at 770 W/m 2 irradiation power. It was realized that, compared to Degussa P-25, the synthesized nano-TiO 2 can be repeatedly used as a new catalyst. The results also proved that Reactive Red 141 is decomposed catalytically due to the pseudo first-order reaction kinetics

  12. Characterization of TiO2–MnO2 composite electrodes synthesized using spark plasma sintering technique

    CSIR Research Space (South Africa)

    Tshephe, TS

    2015-03-01

    Full Text Available and electrochemical stability of the resulting materials were investigated. Relative densities of 99.33% and 98.49% were obtained for 90TiO2–10MnO2 and 80TiO2–10MnO2 when ball was incorporated. The 90TiO2–10MnO2 powder mixed with balls had its Vickers hardness value...

  13. TiO2 nanosheets synthesized by atomic layer deposition for photocatalysis

    Directory of Open Access Journals (Sweden)

    Riyanto Edy

    2016-10-01

    Full Text Available Two-dimensional TiO2 nanosheets were synthesized by atomic layer deposition (ALD on dissolvable sacrificial polymer layer. The photocatalytic performance of free-standing TiO2 nanosheets prepared with different numbers of ALD cycles (100, 300, 500, and 1000 were investigated by evaluating the degradation rates of methyl orange solutions. It is shown that the photocatalytic activity increases due to Ti3+ defect and the locally ordered structures in amorphous TiO2 nanosheets. The difference in the surface areas of nanosheets may also play a crucial role in the photocatalytic activity. The results obtained in this work can have potential applications in fields like water splitting and dye-sensitized solar cells.

  14. The Electrochemical Properties of Low-crystallinity TiO2(B)-Carbon Composite as an Anode Material in Lithium Ion Battery

    International Nuclear Information System (INIS)

    Furuya, Yasuyuki; Zhao, Wenwen; Unno, Masashi; Noguchi, Hideyuki

    2014-01-01

    Highlights: • TiO 2 (B)-carbon composites was synthesized from Lepidocrocite-type compounds. • Tight adhesion between TiO 2 (B) and CNT in the composite is confirmed. • TiO 2 (B)-carbon composite delivers higher capacity than that of bare TiO 2 (B). • TiO 2 (B)-carbon composite exhibits improved rate performance. - Abstract: We have prepared two types TiO 2 (B)-carbon composites from Lepidocrocite-type compounds (K 0.86 Li 0.26 T i1.72 O 4 ) heated at 700 and 900 °C under presence of carbon nanotube (CNT) and glucose as carbon sources. The XRD data shows that it contains a single phase of TiO 2 (B) and the existence of carbon was confirmed by Raman spectra. TEM image confirms that TiO 2 (B) primary particles and carbon nanotube are scattered randomly and contact tightly in the composite. Carbon content in the composite was found to be 5 - 8% and CNT is the major carbonaceous material. The charge and discharge curves of TiO 2 (B)-carbon composite prepared from precursor heated at 700 °C resemble with that of amorphous TiO 2 . The calculated discharge capacity of the composite is 323 mAh g −1 at a cut off voltage of 0.9 V, which is higher than that of bare TiO 2 (B). It is suggested that the electrochemical performance of this material is strongly influenced by both the operating temperature and cut off voltage. The discharge capacity can reach 198 mAh g −1 at 4.5 C rate at a cut off voltage 1.3 V and the coulombic efficiency is over 99.8% after 10 th cycles

  15. Influence of electrical parameters on morphology of nanostructured TiO2 layers developed by electrochemical anodization

    Directory of Open Access Journals (Sweden)

    Strnad Gabriela

    2017-01-01

    Full Text Available Ti6Al4V alloy micro rough surfaces with TiO2 self-organized nanostructured layers were synthesized using electrochemical anodization in phosphate/fluoride electrolyte, at different end potentials (5V, 10V, 15V, and 20 V. The current – time characteristics were recorded, and the link between current evolution and the morphology of developing oxide layers was investigated. On flat surfaces of Ti6Al4V alloy we developed TiO2 layers with different morphologies (random pores, nanopores of 25…50 nm, and highly organized nanotubes of 50…100 nm in diameter depending on electrical parameters of anodization process. In our anodization cell, in optimized conditions, we are able to superimpose nanostructured oxide layers (nanotubular or nanoporous over micro structured surfaces of titanium based materials used for biomedical implants.

  16. Optical properties of TiO2 nanotube arrays fabricated by the electrochemical anodization method

    International Nuclear Information System (INIS)

    Ly, Ngoc Tai; Nguyen, Van Chien; Dao, Thi Hoa; Hoang To, Le Hong; Pham, Duy Long; Do, Hung Manh; Vu, Dinh Lam; Le, Van Hong

    2014-01-01

    Perpendicularly self-aligned TiO 2 nanotube samples of size of 3 × 5 cm 2 were fabricated by the electrochemical anodization method using a solution containing NH 4 F. Influences of the technological conditions such as NH 4 F concentration and anodization voltage were studied. It was found that NH 4 F concentration in the solution and anodization voltage significantly affect the diameter and length of a TiO 2 nanotube. The diameter and the length of a TiO 2 nanotube were observed and estimated by using scanning electron microscopy. It has shown that the largest diameter and the longest length of about 80 nm and 20 μm, respectively, were obtained for the sample anodized in a solution containing 0.4% of NH 4 F, under a voltage of 48 V. Photoluminescence spectra excited by laser lights having wavelengths of 325 and 442 nm (having energies higher and lower than the band gap energy of TiO 2 ) was recorded at room temperature for the TiO 2 nanotube arrays. An abnormal luminescence result was observed. It is experimental evidence that the manufactured TiO 2 nanotube array is an expected material for hydrogen splitting from water by photochemical effect under sunlight as well as for the nano solar cells. (paper)

  17. Electrochemical Characterization of TiO 2 Blocking Layers for Dye-Sensitized Solar Cells

    KAUST Repository

    Kavan, Ladislav; Té treault, Nicolas; Moehl, Thomas; Grä tzel, Michael

    2014-01-01

    Thin compact layers of TiO2 are grown by thermal oxidation of Ti, by spray pyrolysis, by electrochemical deposition, and by atomic layer deposition. These layers are used in dye-sensitized solar cells to prevent recombination of electrons from

  18. The Effect of Deposition on Electrochemical Impedance Properties of TiO2/FTO Photoanodes.

    Czech Academy of Sciences Publication Activity Database

    Balkan, T.; Guler, Z.; Morozová, Magdalena; Dytrych, Pavel; Šolcová, Olga; Sarac, A.S.

    2016-01-01

    Roč. 36, 1-4 (2016), s. 102-111 ISSN 1385-3449 Grant - others:STRC(TR) TBAG 111T051 Institutional support: RVO:67985858 Keywords : nanofiber * titanium dioxide (TiO2) * electrochemical impedance spectroscopy Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.238, year: 2016

  19. XAFS Study on TiO2 Photocatalyst Loaded on Zeolite Synthesized from Steel Slag

    International Nuclear Information System (INIS)

    Kuwahara, Yasutaka; Ohmichi, Tetsutaro; Mori, Kosuke; Katayama, Iwao; Yamashita, Hiromi

    2007-01-01

    The convenient route for the synthesis of Y-zeolites by utilizing steel slag as a material source was developed. Through hydrothermal treatment, well-crystallized Y-zeolite was obtained. We also synthesized TiO2-loaded Y-zeolites by an impregnation method. The structure of titanium oxide species highly dispersed on the zeolite, which couldn't be detected by XRD patterns, was investigated by XAFS analysis. Photocatalytic activity for decomposition of 2-propanol in liquid phase was found to be enhanced by the hydrophobic surface property of zeolite. It has been demonstrated that the zeolite synthesized from steel slag would be applicable as a promising support of TiO2 photocatalyst

  20. Structural and electrical properties of TiO2/ZnO core–shell nanoparticles synthesized by hydrothermal method

    International Nuclear Information System (INIS)

    Vlazan, P.; Ursu, D.H.; Irina-Moisescu, C.; Miron, I.; Sfirloaga, P.; Rusu, E.

    2015-01-01

    TiO 2 /ZnO core–shell nanoparticles were successfully synthesized by hydrothermal method in two stages: first stage is the hydrothermal synthesis of ZnO nanoparticles and second stage the obtained ZnO nanoparticles are encapsulated in TiO 2 . The obtained ZnO, TiO 2 and TiO 2 /ZnO core–shell nanoparticles were investigated by means of X-ray diffraction, transmission electron microscopy, Brunauer, Emmett, Teller and resistance measurements. X-ray diffraction analysis revealed the presence of both, TiO 2 and ZnO phases in TiO 2 /ZnO core–shell nanoparticles. According to transmission electron microscopy images, ZnO nanoparticles have hexagonal shapes, TiO 2 nanoparticles have a spherical shape, and TiO 2 /ZnO core–shell nanoparticles present agglomerates and the shape of particles is not well defined. The activation energy of TiO 2 /ZnO core–shell nanoparticles was about 101 meV. - Graphical abstract: Display Omitted - Highlights: • TiO 2 /ZnO core–shell nanoparticles were synthesized by hydrothermal method. • TiO 2 /ZnO core–shell nanoparticles were investigated by means of XRD, TEM and BET. • Electrical properties of TiO 2 /ZnO core–shell nanoparticles were investigated. • The activation energy of TiO 2 /ZnO core–shell nanoparticles was about E a = 101 meV

  1. Black TiO2 synthesized via magnesiothermic reduction for enhanced photocatalytic activity

    Science.gov (United States)

    Wang, Xiangdong; Fu, Rong; Yin, Qianqian; Wu, Han; Guo, Xiaoling; Xu, Ruohan; Zhong, Qianyun

    2018-04-01

    Utilizing solar energy for hydrogen evolution is a great challenge for its insufficient visible-light power conversion. In this paper, we report a facile magnesiothermic reduction of commercial TiO2 nanoparticles under Ar atmosphere and at 550 °C followed by acid treatment to synthesize reduced black TiO2 powders, which possesses a unique crystalline core-amorphous shell structure composed of disordered surface and oxygen vacancies and shows significantly improved optical absorption in the visible region. The unique core-shell structure and high absorption enable the reduced black TiO2 powders to exhibit enhanced photocatalytic activity, including splitting of water in the presence of Pt as a cocatalyst and degradation of methyl blue (MB) under visible light irradiation. Photocatalytic evaluations indicate that the oxygen vacancies play key roles in the catalytic process. The maximum hydrogen production rates are 16.1 and 163 μmol h-1 g-1 under the full solar wavelength range of light and visible light, respectively. This facile and versatile method could be potentially used for large scale production of colored TiO2 with remarkable enhancement in the visible light absorption and solar-driven hydrogen production.

  2. Raman spectra of TiO2 thin films deposited electrochemically and by spray pyrolysis

    International Nuclear Information System (INIS)

    Shishiyanu, S.; Vartic, V.; Shishiyanu, T.; Stratan, Gh.; Rusu, E.; Zarrelli, M.; Giordano, M.

    2013-01-01

    In this paper we present our experimental results concerning the fabrication of TiO 2 thin films by spray pyrolysis and electrochemical deposition method onto different substrates - Corning glass, Si and optical fibers. The surface morphology of the TiO 2 thin films have been investigated by Atomic Force Microscopy. Raman shift spectra measurements have been done for the optical characterization of the fabricated titania thin films. The post-growth rapid photothermal processing (RPP) at temperatures of 100-800 degrees Celsius for 1-3 min have been applied. Our experimental results prove that by the application of post-growth RPP is possible to essentially improve the crystallinity of the deposited TiO 2 films. (authors)

  3. Gold and TiO2 Nanostructure Surfaces for Assembling of Electrochemical Biosensors

    International Nuclear Information System (INIS)

    Curulli, A.; Zane, D.

    2008-01-01

    Devices based on nano materials are emerging as a powerful and general class of ultrasensitive sensors for the direct detection of biological and chemical species. In this work, we report the preparation and the full characterization of nano materials such as gold nano wires and TiO 2 nano structured films to be used for assembling of electrochemical biosensors. Gold nano wires were prepared by electroless deposition within the pores of polycarbonate particle track-etched membranes (PMS). Glucose oxidase was deposited onto the nano wires using self-assembling monolayer as an anchor layer for the enzyme molecules. Finally, cyclic voltammetry was performed for different enzymes to test the applicability of gold nano wires as biosensors. Considering another interesting nano material, the realization of functionalized TiO 2 thin films on Si substrates for the immobilization of enzymes is reported. Glucose oxidase and horseradish peroxidase immobilized onto TiO 2 -based nano structured surfaces exhibited a pair of well-defined and quasi reversible voltammetric peaks. The electron exchange between the enzyme and the electrodes was greatly enhanced in the TiO 2 nano structured environment. The electrocatalytic activity of HRP and GOD embedded in TiO 2 electrodes toward H 2 O 2 and glucose, respectively, may have a potential perspective in the fabrication of third-generation biosensors based on direct electrochemistry of enzymes.

  4. Photocatalytic degradation of methyl orange with W-doped TiO2 synthesized by a hydrothermal method

    International Nuclear Information System (INIS)

    Tian Hua; Ma Junfeng; Li Kang; Li Jinjun

    2008-01-01

    Nanosized W-doped TiO 2 photocatalysts were synthesized by a simple hydrothermal method, and characterized by energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and BET surface area analyzer. The photocatalytic activity of undoped TiO 2 and W-doped TiO 2 photocatalysts was evaluated by the photocatalytic oxidation degradation of methyl orange in aqueous solution. The results show that the photocatalytic activity of the W-doped TiO 2 photocatalyst is much higher than that of undoped TiO 2 , and the optimum percentage of W doped is 2.0 mol%. The enhanced photocatalytic activity of the doped photocatalyst may be attributed to the increase in the charge separation efficiency and the presence of surface acidity

  5. Electrochemical & osteoblast adhesion study of engineered TiO2 nanotubular surfaces on titanium alloys

    International Nuclear Information System (INIS)

    Rahman, Zia Ur; Haider, Waseem; Pompa, Luis; Deen, K.M.

    2016-01-01

    TiO 2 nanotubes were grafted on the surface of cpTi, Ti6Al4V and Ti6Al4V-ELI with the aim to provide a new podium for human pre-osteoblast cell (MC3T3) adhesion and proliferation. The surface morphology and chemistry of these alloys were examined with scanning electron microscopy and energy dispersive x-ray spectroscopy. TiO 2 nanotubes were further characterized by cyclic potentiodynamic polarization tests and electrochemical impedance spectroscopy. The vertically aligned nanotubes were subjected to pre-osteoblast cell proliferation in order to better understand cell–material interaction. The study demonstrated that these cells interact differently with nanotubes of different titanium alloys. The significant acceleration in the growth rate of pre-osteoblast cell adhesion and proliferation is also witnessed. Additionally, the cytotoxicity of the leached metal ions was evaluated by using a tetrazolium-based bio-assay, MTS. Each group of data was operated for p < 0.05, concluded one way ANOVA to investigate the significance difference. - Highlights: • TiO 2 nanotubes were grafted on cpTi, Ti6Al4V and Ti6Al4V-ELI via anodization. • MC3T3 cells interact differently with nanotubes of different titanium alloys. • TiO 2 nanotubes have a positive impact on the osteoblast cell viability.

  6. 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.

  7. Chemically synthesized TiO2 and PANI/TiO2 thin films for ethanol sensing applications

    Science.gov (United States)

    Gawri, Isha; Ridhi, R.; Singh, K. P.; Tripathi, S. K.

    2018-02-01

    Ethanol sensing properties of chemically synthesized titanium dioxide (TiO2) and polyaniline/titanium dioxide nanocomposites (PANI/TiO2) had been performed at room temperature. In-situ oxidative polymerization process had been employed with aniline as a monomer in presence of anatase titanium dioxide nanoparticles. The prepared samples were structurally and morphologically characterized by x-ray diffraction, fourier transform infrared spectra, high resolution-transmission electron microscopy and field emission-scanning electron microscopy. The crystallinity of PANI/TiO2 nanocomposite was revealed by XRD and FTIR spectra confirmed the presence of chemical bonding between the polymer chains and metal oxide nanoparticles. HR-TEM micrographs depicted that TiO2 particles were embedded in polymer matrix, which provides an advantage over pure TiO2 nanoparticles in efficient adsorption of vapours. These images also revealed that the TiO2 nanoparticles were irregular in shape with size around 17 nm. FE-SEM studies revealed that in the porous structure of PANI/TiO2 film, the intercalation of TiO2 in PANI chains provides an advantage over pure TiO2 film for uniform interaction with ethanol vapors. The sensitivity values of prepared samples were examined towards ethanol vapours at room temperature. The PANI/TiO2 nanocomposite exhibited better sensing response and faster response-recovery examined at different ethanol concentrations ranging from 5 ppm to 20 ppm in comparison to pure TiO2 nanoparticles. The increase in vapour sensing of PANI/TiO2 sensing film as compared to pure TiO2 film had been explained in detail with the help of gas sensing mechanism of TiO2 and PANI/TiO2. This provides strong evidence that gas sensing properties of TiO2 had been considerably improved and enhanced with the addition of polymer matrix.

  8. Electrochemical Characterization of TiO 2 Blocking Layers for Dye-Sensitized Solar Cells

    KAUST Repository

    Kavan, Ladislav

    2014-07-31

    Thin compact layers of TiO2 are grown by thermal oxidation of Ti, by spray pyrolysis, by electrochemical deposition, and by atomic layer deposition. These layers are used in dye-sensitized solar cells to prevent recombination of electrons from the substrate (FTO or Ti) with the hole-conducting medium at this interface. The quality of blocking is evaluated electrochemically by methylviologen, ferro/ferricyanide, and spiro-OMeTAD as the model redox probes. Two types of pinholes in the blocking layers are classified, and their effective area is quantified. Frequency-independent Mott-Schottky plots are fitted from electrochemical impedance spectroscopy. Certain films of the thicknesses of several nanometers allow distinguishing the depletion layer formation both in the TiO2 film and in the FTO substrate underneath the titania film. The excellent blocking function of thermally oxidized Ti, electrodeposited film (60 nm), and atomic-layer-deposited films (>6 nm) is documented by the relative pinhole area of less than 1%. However, the blocking behavior of electrodeposited and atomic-layer-deposited films is strongly reduced upon calcination at 500 °C. The blocking function of spray-pyrolyzed films is less good but also less sensitive to calcination. The thermally oxidized Ti is well blocking and insensitive to calcination. © 2014 American Chemical Society.

  9. Adsorption of methyl orange by synthesized and functionalized-CNTs with 3-aminopropyltriethoxysilane loaded TiO2 nanocomposites.

    Science.gov (United States)

    Ahmad, Amirah; Razali, Mohd Hasmizam; Mamat, Mazidah; Mehamod, Faizatul Shimal Binti; Anuar Mat Amin, Khairul

    2017-02-01

    This study aims to develop a highly efficient adsorbent material. CNTs are prepared using a chemical vapor deposition method with acetylene and synthesized mesoporous Ni-MCM41 as the carbon source and catalyst, respectively, and are then functionalized using 3-aminopropyltriethoxysilane (APTES) through the co-condensation method and loaded with commercial TiO 2 . Results of X-ray powder diffraction (XRD), Raman spectra, and Fourier transform infrared spectroscopy (FTIR) confirm that the synthesized CNTs grown are multi-walled carbon nanotubes (MWNTs). Transmission electron microscopy shows good dispersion of TiO 2 nanoparticles onto functionalized-CNTs loaded TiO 2 , with the diameter of a hair-like structure measuring between 3 and 8 nm. The functionalized-CNTs loaded TiO 2 are tested as an adsorbent for removal of methyl orange (MO) in aqueous solution, and results show that 94% of MO is removed after 10 min of reaction, and 100% after 30 min. The adsorption kinetic model of functionalized-CNTs loaded TiO 2 follows a pseudo-second order with a maximum adsorption capacity of 42.85 mg/g. This study shows that functionalized-CNTs loaded TiO 2 has considerable potential as an adsorbent material due to the short adsorption time required to achieve equilibrium. Copyright © 2016 Elsevier Ltd. All rights reserved.

  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. Structural, optical, and magnetic properties of polycrystalline Co-doped TiO2 synthesized by solid-state method

    International Nuclear Information System (INIS)

    Bouaine, Abdelhamid; Schmerber, G.; Ihiawakrim, D.; Derory, A.

    2012-01-01

    Highlights: ► Influence of Co doping on the TiO 2 tetragonal structure. ► Decrease of the energy band gap after doping with Co atoms. ► Appearance of ferromagnetism in Co-doped TiO 2 diluted magnetic semiconductors. - Abstract: We have used a solid-state method to synthesize polycrystalline Co-doped TiO 2 diluted magnetic semiconductors (DMSs) with Co concentrations of 0, and 0.5 at.%. X-ray diffraction patterns reveal that Co doped TiO 2 crystallizes in the rutile tetragonal structure with no additional peaks. Transmission electron microscopy (TEM) did not indicate the presence of magnetic parasitic phases and confirmed that Co ions are uniformly distributed inside the samples. Optical absorbance measurements showed an energy band gap which decreases after doping with the Co atoms into the TiO 2 matrix. Magnetization measurements revealed a paramagnetic behavior for the as-prepared Co-doped TiO 2 and a ferromagnetic behavior for the same samples after annealed under a mixture of H 2 /N 2 atmosphere.

  12. An innovative approach to synthesize highly-ordered TiO2 nanotubes.

    Science.gov (United States)

    Isimjan, Tayirjan T; Yang, D Q; Rohani, Sohrab; Ray, Ajay K

    2011-02-01

    An innovative route to prepare highly-ordered and dimensionally controlled TiO2 nanotubes has been proposed using a mild sonication method. The nanotube arrays were prepared by the anodization of titanium in an electrolyte containing 3% NH4F and 5% H2O in glycerol. It is demonstrated that the TiO2 nanostructures has two layers: the top layer is TiO2 nanowire and underneath is well-ordered TiO2 nanotubes. The top layer can easily fall off and form nanowires bundles by implementing a mild sonication after a short annealing time. We found that the dimensions of the TiO2 nanotubes were only dependent on the anodizing condition. The proposed technique may be extended to fabricate reproducible well-ordered TiO2 nanotubes with large area on other metals.

  13. An Experimental Study on the Shape Changes of TiO2 Nanocrystals Synthesized by Microemulsion-Solvothermal Method

    Directory of Open Access Journals (Sweden)

    Wei Kong

    2011-01-01

    Full Text Available Titanium dioxide (TiO2 nanocrystals of different shape were successfully synthesized in a new microemulsion system through a solvothermal process. The TiO2 nanocrystals were prepared from the reaction of tetrabutyl titanate (TBT, H2O, and oleic acid (OA, which were used as solvent and surfactant at 300∘C and 240∘C in a stainless steel autoclave. The sphere, polygon, and rhombus-shaped nanocrystals have been prepared at 300∘C and the dot- and- rod shaped nanocrystals have been synthesized at 240∘C. The effect of the reaction time on the shape and size of TiO2 nanocrystals in this method was studied in the present paper. The size distribution of TiO2 nanocrystals prepared at 300∘C for different hours is also studied. In addition, an attempt to describe the mechanism of shape change of TiO2 nanocrystals was presented in this paper.

  14. Electrochemically conductive treatment of TiO2 nanotube arrays in AlCl3 aqueous solution for supercapacitors

    Science.gov (United States)

    Zhong, Wenjie; Sang, Shangbin; Liu, Yingying; Wu, Qiumei; Liu, Kaiyu; Liu, Hongtao

    2015-10-01

    Highly ordered TiO2 nanotube arrays (NTAs) with excellent stability and large specific surface area make them competitive using as supercapacitor materials. Improving the conductivity of TiO2 is of great concern for the construction of high-performance supercapacitors. In this work, we developed a novel approach to improve the performance of TiO2 materials, involving the fabrication of Al-doped TiO2 NTAs by a simple electrochemical cathodic polarization treatment in AlCl3 aqueous solution. The prepared Al-doped TiO2 NTAs exhibited excellent electrochemical performances, attributing to the remarkably improved electrical conductivity (i.e., from approx. 10 kΩ to 20 Ω). Further analysis showed that Al3+ ions rather than H+ protons doped into TiO2 lattice cause this high conductivity. A MnO2/Al-TiO2 composite was evaluated by cyclic voltammetry, and achieved the specific capacitance of 544 F g-1, and the Ragone plot of the sample showed a high power density but less reduction of energy density. These results indicate that the MnO2/Al-TiO2 NTAs sample could be served as a promising electrode material for high -performance supercapacitors.

  15. THERMALLY STABLE NANOCRYSTALLINE TIO2 PHOTOCATALYSTS SYNTHESIZED VIA SOL-GEL METHODS MODIFIED WITH IONIC LIQUID AND SURFACTANT MOLECULES

    Science.gov (United States)

    Recently, sol-gel methods employing ionic liquids (ILs) have shown significant implications for the synthesis of well-defined nanostructured inorganic materials. Herein, we synthesized nanocrystalline TiO2 particles via an alkoxide sol-gel method employing a water-immi...

  16. TiO2 coated Si nanowire electrodes for electrochemical double layer capacitors in room temperature ionic liquid

    International Nuclear Information System (INIS)

    Konstantinou, F; Shougee, A; Albrecht, T; Fobelets, K

    2017-01-01

    Three TiO 2 deposition processes are used to coat the surface of Si nanowire array electrodes for electrochemical double layer capacitors in room temperature ionic liquid [Bmim][NTF 2 ]. The fabrication processes are based on wet chemistry only and temperature treatments are kept below 450 °C. Successful TiO 2 coatings are found to be those that are carried out at low pressure and with low TiO 2 coverage to avoid nanowires breakage. The best TiO 2 coated Si nanowire array electrode in [Bmim][NTF 2 ] showed energy densities of 0.9 Wh·kg −1 and power densities of 2.2 kW·kg −1 with a nanowire length of ∼10 µ m. (paper)

  17. TiO2/PCL hybrid materials synthesized via sol–gel technique for biomedical applications

    International Nuclear Information System (INIS)

    Catauro, M.; Bollino, F.; Papale, F.; Marciano, S.; Pacifico, S.

    2015-01-01

    The aim of the present work has been the synthesis of organic/inorganic hybrid materials based on titanium dioxide and poly(ε-caprolactone) (PCL) to be used in the biomedical field. Several materials have been synthesized using sol–gel methods by adding different amounts of polymer to the inorganic sol. The obtained gels have been characterized using Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) and atomic force microscopy (AFM). The FT-IR data allowed us to hypothesize that the structure formed was that of an interpenetrating network, realized by hydrogen bonds between Ti-OH groups in the sol–gel intermediate species and carbonyl groups in the polymer repeating units. SEM and AFM analyses highlighted that the obtained materials were nanostructurated hybrids. To evaluate the biological properties of the hybrids, their bioactivity and cytotoxicity were investigated as a function of the PCL amount. The bioactivity of the synthesized systems was proven by the formation of a hydroxyapatite layer on the surface of samples soaked in a fluid simulating human blood plasma (SBF). MTT cytotoxicity tests and Trypan Blue dye exclusion tests were carried out exposing NIH-3T3 mouse embryonic fibroblasts for 24 and 48 h to extracts from the investigated hybrid materials. The results showed that all the hybrids had a non-cytotoxic effect on target cells. - Highlights: • TiO 2 /PCL hybrids were obtained by the sol–gel process for biomedical applications. • Synthesized materials were found to be first-class hybrid nanocomposites. • Hybrids appear to be bioactive, a fundamental characteristic for osseointegration. • MTT and Trypan Blue viability test show that the materials are biocompatible. • The organic phase is able to modulate the biocompatibility of the materials

  18. Photocatalytical Properties and Theoretical Analysis of N, Cd-Codoped TiO2 Synthesized by Thermal Decomposition Method

    Directory of Open Access Journals (Sweden)

    Hongtao Gao

    2012-01-01

    Full Text Available N, Cd-codoped TiO2 have been synthesized by thermal decomposition method. The products were characterized by X-ray diffraction (XRD, scanning electron microscope (SEM, UV-visible diffuse reflectance spectra (DRS, X-ray photoelectron spectroscopy (XPS, and Brunauer-Emmett-Teller (BET specific surface area analysis, respectively. The products represented good performance in photocatalytic degradation of methyl orange. The effect of the incorporation of N and Cd on electronic structure and optical properties of TiO2 was studied by first-principle calculations on the basis of density functional theory (DFT. The impurity states, introduced by N 2p or Cd 5d, lied between the valence band and the conduction band. Due to dopants, the band gap of N, Cd-codoped TiO2 became narrow. The electronic transition from the valence band to conduction band became easy, which could account for the observed photocatalytic performance of N, Cd-codoped TiO2. The theoretical analysis might provide a probable reference for the experimentally element-doped TiO2 synthesis.

  19. TiO2 synthesized by microwave assisted solvothermal method: Experimental and theoretical evaluation

    International Nuclear Information System (INIS)

    Moura, K.F.; Maul, J.; Albuquerque, A.R.; Casali, G.P.; Longo, E.; Keyson, D.; Souza, A.G.; Sambrano, J.R.; Santos, I.M.G.

    2014-01-01

    In this study, a microwave assisted solvothermal method was used to synthesize TiO 2 with anatase structure. The synthesis was done using Ti (IV) isopropoxide and ethanol without templates or alkalinizing agents. Changes in structural features were observed with increasing time of synthesis and evaluated using periodic quantum chemical calculations. The anatase phase was obtained after only 1 min of reaction besides a small amount of brookite phase. Experimental Raman spectra are in accordance with the theoretical one. Micrometric spheres constituted by nanometric particles were obtained for synthesis from 1 to 30 min, while spheres and sticks were observed after 60 min. - Graphical abstract: FE-SEM images of anatase obtained with different periods of synthesis associated with the order–disorder degree. Display Omitted - Highlights: • Anatase microspheres were obtained by the microwave assisted hydrothermal method. • Only ethanol and titanium isopropoxide were used as precursors during the synthesis. • Raman spectra and XRD patterns were compared with quantum chemical calculations. • Time of synthesis increased the short-range disorder in one direction and decreased in another

  20. Influences of Mg Doping on the Electrochemical Performance of TiO2 Nanodots Based Biosensor Electrodes

    Directory of Open Access Journals (Sweden)

    M. S. H. Al-Furjan

    2014-01-01

    Full Text Available Electrochemical biosensors are essential for health monitors to help in diagnosis and detection of diseases. Enzyme adsorptions on biosensor electrodes and direct electron transfer between them have been recognized as key factors to affect biosensor performance. TiO2 has a good protein adsorption ability and facilitates having more enzyme adsorption and better electron transfer. In this work, Mg ions are introduced into TiO2 nanodots in order to further improve electrode performance because Mg ions are considered to have good affinity with proteins or enzymes. Mg doped TiO2 nanodots on Ti substrates were prepared by spin-coating and calcining. The effects of Mg doping on the nanodots morphology and performance of the electrodes were investigated. The density and size of TiO2 nanodots were obviously changed with Mg doping. The sensitivity of 2% Mg doped TiO2 nanodots based biosensor electrode increased to 1377.64 from 897.8 µA mM−1 cm−2 and its KMapp decreases to 0.83 from 1.27 mM, implying that the enzyme achieves higher catalytic efficiency due to better affinity of the enzyme with the Mg doped TiO2. The present work could provide an alternative to improve biosensor performances.

  1. Genotoxic and cytotoxic activity of green synthesized TiO2 nanoparticles

    Science.gov (United States)

    Koca, Fatih Doğan; Duman, Fatih

    2018-03-01

    Nowadays, nanomaterials that are smaller than 100 nm in size are very attractive owing to their enhanced physicochemical properties. Although they have been used widely for industrial applications, their toxicity still remains a problem. This article is a new record of the synthesis of titanium dioxide nanoparticles (TiO2 NPs) by a Mentha aquatica leaf extract and determination of its toxicity to rat marrow mesenchymal stem cells. In this study, we aimed to determine the genotoxic and cytotoxic effects of biologically synthetized TiO2 NPs. The characteristic peak of the nanomaterial was observed at 354 nm. The mean size of the nanomaterial was measured to be 69 nm from SEM images. According to zeta analysis, the surface charge of the nanomaterial was - 37.6 mV. The crystalline structure of the nanomaterial was determined using XRD analysis. It was concluded that the obtained nanomaterial was TiO2 The results of the FT-IR analysis showed that the functional groups that were found in the plant extract could play an important role in the formation and stabilization of TiO2 NPs. The effective size of the TiO2 NPs was found to be 304 nm using DLS analysis. The TGA analysis results showed that the total mass loss was 4% at 900 °C. According to DNA cleavage analysis results, TiO2 NPs cause damage to the plasmid pBR322 DNA in a concentration-dependant matter. It has been noted that TiO2 NPs lead to decreased cell viability during increased time and concentration of applications on rat marrow mesenchymal stem cells. It has also been determined that bulk TiO2 causes a greater reduction in the stem cell viability compared to the biosynthesized NPs. The obtained results could be useful for further application and toxicity studies.

  2. Au Nanoparticles Decorated TiO2 Nanotube Arrays as a Recyclable Sensor for Photoenhanced Electrochemical Detection of Bisphenol A.

    Science.gov (United States)

    Hu, Liangsheng; Fong, Chi-Chun; Zhang, Xuming; Chan, Leo Lai; Lam, Paul K S; Chu, Paul K; Wong, Kwok-Yin; Yang, Mengsu

    2016-04-19

    A photorefreshable and photoenhanced electrochemical sensing platform for bisphenol A (BPA) detection based on Au nanoparticles (NPs) decorated carbon doped TiO2 nanotube arrays (TiO2/Au NTAs) is described. The TiO2/Au NTAs were prepared by quick annealing of anodized nanotubes in argon, followed by controllable electrodeposition of Au NPs. The decoration of Au NPs not only improved photoelectrochemical behavior but also enhanced electrocatalytic activities of the resulted hybrid NTAs. Meanwhile, the high photocatalytic activity of the NTAs allowed the electrode to be readily renewed without damaging the microstructures and surface states after a short UV treatment. The electrochemical detection of BPA on TiO2/Au NTAs electrode was significantly improved under UV irradiation as the electrode could provide fresh reaction surface continuously and the further increased photocurrent resulting from the improved separation efficiency of the photogenerated electron-hole pairs derived from the consumption of holes by BPA. The results showed that the refreshable TiO2/Au NTAs electrode is a promising sensor for long-term BPA monitoring with the detection limit (S/N = 3) of 6.2 nM and the sensitivity of 2.8 μA·μM(-1)·cm(-2).

  3. Eu"2"+ doped TiO_2 nano structures synthesized by HYSYCVD for thermoluminescence dosimetry

    International Nuclear Information System (INIS)

    Perez A, J. A.; Leal C, A. L.; Melendrez A, R.; Barboza F, M.

    2016-10-01

    Titania (TiO_2) has attracted interest owing his potential applications as dosimetry material given his excellent optical, electrical and thermal properties and the ability to shape his structure make TiO_2 suitable for research and dosimetry applications. In this work, a systematic study to know the magnitude of processing parameters influence on thermoluminescent properties of undoped (TiO_2) and doped (TiO_2:Eu"2"+) nano materials obtained by hybrid precursor systems chemical vapor deposition (HYSYCVD) technique is presented. Synthesis of one dimension nano structures of TiO_2:Eu"2"+ was carried out using K_2TiF_6 and EuCl_2 as dopant at 0.5, 1, 2.5 and 5 wt %. The nano structures samples were irradiated with β-ray in a doses range of 0.083-3000 Gy. All thermoluminescence (Tl) glow curves showed 3 broad Tl peaks around 373, 473 and 573 K, and a dosimetric linear behavior from 0.083 to 300 Gy. The Tl has a good reproducibility, with deviations of around 5%, making these TiO_2:Eu"2"+ nano materials suitable for dosimetric applications. (Author)

  4. Hydroxyapatite/gelatin functionalized graphene oxide composite coatings deposited on TiO2 nanotube by electrochemical deposition for biomedical applications

    International Nuclear Information System (INIS)

    Yan, Yajing; Zhang, Xuejiao; Mao, Huanhuan; Huang, Yong; Ding, Qiongqiong; Pang, Xiaofeng

    2015-01-01

    Highlights: • Graphene oxide cross-linked gelatin was firstly employed as reinforcement fillers in hydroxyapatite coatings by electrochemical deposition process on TiO 2 nanotube arrays. • Gelatin functionalized graphene oxide induced the formation of hydroxyapatite coatings. • The success of gelatin and graphene oxide incorporation was evidenced with FTIR and XPS. • The synthesized composite coatings showed good biocompatibility and no adverse effect in cell culture tests. - Abstract: Graphene oxide cross-linked gelatin was employed as reinforcement fillers in hydroxyapatite coatings by electrochemical deposition process on TiO 2 nanotube arrays (TNs). The TNs were grown on titanium by electrochemical anodization in hydrofluoric electrolyte using constant voltage. Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Field emission scanning electron microscopy equipped with energy dispersive X-ray analysis and biological studies were used to characterize the coatings. The corrosion resistance of the coatings was also investigated by electrochemical method in simulated body fluid solution

  5. Preparation of RuO2-TiO2/Nano-graphite composite anode for electrochemical degradation of ceftriaxone sodium.

    Science.gov (United States)

    Li, Dong; Guo, Xiaolei; Song, Haoran; Sun, Tianyi; Wan, Jiafeng

    2018-06-05

    Graphite-like material is widely used for preparing various electrodes for wastewater treatment. To enhance the electrochemical degradation efficiency of Nano-graphite (Nano-G) anode, RuO 2 -TiO 2 /Nano-G composite anode was prepared through the sol-gel method and hot-press technology. RuO 2 -TiO 2 /Nano-G composite was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and N 2 adsorption-desorption. Results showed that RuO 2 , TiO 2 and Nano-G were composited successfully, and RuO 2 and TiO 2 nanoparticles were distributed uniformly on the surface of Nano-G sheet. Specific surface area of RuO 2 -TiO 2 /Nano-G composite was higher than that of TiO 2 /Nano-G composite and Nano-G. Electrochemical performances of RuO 2 -TiO 2 /Nano-G anode were investigated by cyclic voltammetry, electrochemical impedance spectroscopy. RuO 2 -TiO 2 /Nano-G anode was applied to electrochemical degradation of ceftriaxone. The generation of hydroxyl radical (OH) was measured. Results demonstrated that RuO 2 -TiO 2 /Nano-G anode displayed enhanced electrochemical degradation efficiency towards ceftriaxone and yield of OH, which is derived from the synergetic effect between RuO 2 , TiO 2 and Nano-G, which enhance the specific surface area, improve the electrochemical oxidation activity and lower the charge transfer resistance. Besides, the possible degradation intermediates and pathways of ceftriaxone sodium were identified. This study may provide a viable and promising prospect for RuO 2 -TiO 2 /Nano-G anode towards effective electrochemical degradation of antibiotics from wastewater. Copyright © 2018 Elsevier B.V. All rights reserved.

  6. The comparison of photocatalytic activity of synthesized TiO2 and ZrO2 nanosize onto wool fibers

    International Nuclear Information System (INIS)

    Moafi, Hadi Fallah; Shojaie, Abdollah Fallah; Zanjanchi, Mohammad Ali

    2010-01-01

    TiO 2 and ZrO 2 nanocrystals were successfully synthesized and deposited onto wool fibers using the sol-gel technique at low temperature. The photocatalytic activities of TiO 2 -coated and ZrO 2 -coated wool fibers were measured by studying photodegradation of methylene blue and eosin yellowish dyes. The initial and the treated samples were characterized by several techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS) and X-ray diffraction. The TEM study shows dispersed particles with 10-30 nm in size for TiO 2 -coated and 20-40 nm in size for ZrO 2 -coated samples on the fiber surface. Comparison of the photocatalytic activity of the coated samples reveals superiority of TiO 2 modified sample with respect to that of ZrO 2 for degradation of both dyes. Our observations indicate that by applying this technique to the fabrics, self-cleaning materials could be designed for practical application.

  7. 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)

  8. Electrochemical Behavior of TiO2 Nanoparticle Doped WO3 Thin Films

    Directory of Open Access Journals (Sweden)

    Suvarna R. Bathe

    2014-01-01

    Full Text Available Nanoparticle TiO2 doped WO3 thin films by pulsed spray pyrolysis technique have been studied on fluorine tin doped (FTO and glass substrate. XRD shows amorphous nature for undoped and anatase phase of TiO2 having (101 plane for nanoparticle TiO2 doped WO3 thin film. SEM shows microfibrous reticulated porous network for WO3 with 600 nm fiber diameter and nanocrystalline having size 40 nm for TiO2 nanoparticle doped WO3 thin film. TiO2 nanoparticle doped WO3 thin film shows ~95% reversibility due to may be attributed to nanocrystalline nature of the film, which helpful for charge insertion and deinsertion process. The diffusion coefficient for TiO2 nanoparticle doped WO3 film is less than undoped WO3.

  9. Optical and Morphological Properties of ZnO- and TiO2-Derived Nanostructures Synthesized via a Microwave-Assisted Hydrothermal Method

    Directory of Open Access Journals (Sweden)

    Nosipho Moloto

    2012-01-01

    Full Text Available A microwave-assisted hydrothermal method was used to synthesize ZnO and TiO2 nanostructures. The experimental results show that the method resulted in crystalline monodispersed ZnO nanorods that have pointed tips with hexagonal crystal phase. TiO2 nanotubes were also formed with minimum bundles. The mechanism for the formation of the tubes was validated by HRTEM results. The optical properties of both ZnO and TiO2 nanostructures showed characteristics of strong quantum confinement regime. The photoluminescence spectrum of TiO2 nanotubes shows good improvement from previously reported data.

  10. Photocatalytic behaviors and structural characterization of nanocrystalline Fe-doped TiO2 synthesized by mechanical alloying

    International Nuclear Information System (INIS)

    Kim, Dong Hyun; Hong, Hyun Seon; Kim, Sun Jae; Song, Jae Sung; Lee, Kyung Sub

    2004-01-01

    Nanocrystalline Fe-doped TiO 2 powders were synthesized by mechanical alloying (MA) with varying Fe contents from 0 up to 4.8 wt.% to shift the absorption threshold into the visible light region. The photocatalytic feasibility of the Fe-doped TiO 2 powder was evaluated by quantifying the visible light absorption capacity using ultraviolet and visible (UV-Vis) spectroscopy and photoluminescence spectroscopy. Effects of Fe additions on the crystal structures and the morphologies of the Fe-doped powders were also investigated as a function of the doping content using transmission electron microscopy-electron diffraction pattern (TEM-EDP), X-ray diffraction (XRD) and energy dispersive X-ray (EDAX) and X-ray photoelectron spectroscopy (XPS). The UV-Vis study showed that the UV absorption for the Fe-doped powder moved to a longer wavelength (red shift) and the photoefficiency was enhanced. Based on the analysis of the photoluminescence spectra, the red shift was believed to be induced by localizing the dopant level near the valence band of TiO 2 . The UV-Vis absorption depended on the Fe concentration. TEM-EDP and XRD investigations showed that the Fe-doped powder had a rutile phase in which the added Fe atoms were dissolved. The rutile phase was composed of spherical particles and chestnut bur shaped particles, resulting in a larger surface area than the spherical P-25 powder

  11. Electrochemical reduction induced self-doping of Ti3+ for efficient water splitting performance on TiO2 based photoelectrodes

    KAUST Repository

    Zhang, Zhonghai

    2013-01-01

    Hetero-element doping (e.g., N, F, C) of TiO2 is inevitably accompanied by significantly increased structural defects due to the dopants\\' nature being foreign impurities. Very recently, in situ self-doping with homo-species (e.g., Ti3+) has been emerging as a rational solution to enhance TiO2 photoactivity within both UV and visible light regions. Herein we demonstrate that conventional electrochemical reduction is indeed a facile and effective strategy to induce in situ self-doping of Ti3+ into TiO2 and the self-doped TiO2 photoelectrodes showed remarkably improved and very stable water splitting performance. In this study, hierarchical TiO2 nanotube arrays (TiO2 NTs) were chosen as TiO2 substrates and then electrochemically reduced under varying conditions to produce Ti3+ self-doped TiO2 NTs (ECR-TiO2 NTs). The optimized saturation photocurrent density and photoconversion efficiency on the ECR-TiO2 NTs under simulated AM 1.5G illumination were identified to be 2.8 mA cm-2 at 1.23 V vs. RHE and 1.27% respectively, which are the highest values ever reported for TiO 2 based photoelectrodes. The electrochemical impedance spectra measurement confirms that the electrochemical induced Ti3+ self-doping improved the electrical conductivity of the ECR-TiO2 NTs. The versatility and effectiveness of the electrochemical reduction method for Ti3+ self-doping in P25 based TiO2 was also examined and confirmed. This journal is © 2013 the Owner Societies.

  12. Simple fabrication of TiO2/C nanocomposite with enhanced electrochemical performance for lithium-ion batteries

    International Nuclear Information System (INIS)

    Bai, Xue; Li, Tao; Qi, Yong-Xin; Gao, Xue-Ping; Yin, Long-Wei; Li, Hui; Zhu, Hui-Ling; Lun, Ning; Bai, Yu-Jun

    2015-01-01

    TiO 2 /C nanocomposites were fabricated by simple hydrolysis of tetrabutyl titanate to yield TiO 2 nanoparticles followed by carbonizing the mixture of glucose and TiO 2 at 600 °C. By merely varying the weight ratio of glucose:TiO 2 , the electrochemical performance of the composites could be optimized significantly. At a ratio of 0.8, the composite exhibits a high reversible capacity of 283.7 mA h g −1 after cycling 100 times at a current density of 100 mA g −1 , as well as the capacities of 245.1, 213.6, 179.9 and 136.6 mA h g −1 at the corresponding densities of 200, 400, 800 and 1600 mA g −1 . After cycling 1000 times at 500 mA g −1 , a capacity of 122.8 mA h g −1 was retained for the composite with a ratio of 0.8, and even a capacity of 149.1 mA h g −1 for the composite with a ratio of 0.7. The enhanced performance is ascribed to the carbon-coated TiO 2 nanoparticles uniformly embedding in the carbon matrix with appropriate carbon content

  13. Photo-electrochemical properties of graphene wrapped hierarchically branched nanostructures obtained through hydrothermally transformed TiO2 nanotubes

    Science.gov (United States)

    Rambabu, Y.; Jaiswal, Manu; Roy, Somnath C.

    2017-10-01

    Hierarchically structured nanomaterials play an important role in both light absorption and separation of photo-generated charges. In the present study, hierarchically branched TiO2 nanostructures (HB-MLNTs) are obtained through hydrothermal transformation of electrochemically anodized TiO2 multi-leg nanotubes (MLNT) arrays. Photo-anodes based on HB-MLNTs demonstrated 5 fold increase in applied bias to photo-conversion efficiency (%ABPE) over that of TiO2 MLNTs without branches. Further, such nanostructures are wrapped with reduced graphene oxide (rGO) films to enhance the charge separation, which resulted in ∼6.5 times enhancement in %ABPE over that of bare MLNTs. We estimated charge transport (η tr) and charge transfer (η ct) efficiencies by analyzing the photo-current data. The ultra-fine nano branches grown on the MLNTs are effective in increasing light absorption through multiple scattering and improving charge transport/transfer efficiencies by enlarging semiconductor/electrolyte interface area. The charge transfer resistance, interfacial capacitance and electron decay time have been estimated through electrochemical impedance measurements which correlate with the results obtained from photocurrent measurements.

  14. High-performance and renewable supercapacitors based on TiO2 nanotube array electrodes treated by an electrochemical doping approach

    International Nuclear Information System (INIS)

    Wu, Hui; Li, Dongdong; Zhu, Xufei; Yang, Chunyan; Liu, Dongfang; Chen, Xiaoyuan; Song, Ye; Lu, Linfeng

    2014-01-01

    Although one-dimensional anodic TiO 2 nanotube arrays have shown promise as supercapacitor electrode materials, their poor electronic conductivity embarrasses the practical applications. Here, we develop a simple electrochemical doping method to significantly improve the electronic conductivity and the electrochemical performances of TiO 2 nanotube electrodes. These TiO 2 nanotube electrodes treated by the electrochemical hydrogenation doping (TiO 2 -H) exhibit a very high average specific capacitance of 20.08 mF cm −2 at a current density of 0.05 mA cm −2 , ∼20 times more than the pristine TiO 2 nanotube electrodes. The improved electrochemical performances can be attributed to ultrahigh conductivity of TiO 2 -H due to the introduction of interstitial hydrogen ions and oxygen vacancies by the doping. The supercapacitor device assembled by the doped electrodes delivers a specific capacitance of 5.42 mF cm −2 and power density of 27.66 mW cm −2 , on average, at the current density of 0.05 mA cm −2 . The device also shows an outstanding rate capability with 60% specific capacitance retained when the current density increases from 0.05 to 4.00 mA cm −2 . More interestingly, the electrochemical performances of the supercapacitor after cycling can be recovered by the same doping process. This strategy boosts the performances of the supercapacitor, especially cycling stability

  15. Electrochemical and spectroelectrochemical characterization of different mesoporous TiO2 film electrodes for the immobilization of Cytochrome c

    Science.gov (United States)

    Katsiaounis, Stavros; Tiflidis, Christina; Tsekoura, Christina; Topoglidis, Emmanuel

    2018-03-01

    In this work three different mesoporous TiO2 film electrodes were prepared and used for the immobilization of Cytochrome c (Cyt-c). Films prepared via a standard sol-gel route (SG-films) were compared with commercially available benchmark nanotitania materials, namely P25 Degussa (P25-films) and Dyesol nanopaste (Dyesol films). Their properties, film deposition characteristics and their abilities to adsorb protein molecules in a stable and functional way were examined. We investigated whether it is possible, rather than preparing TiO2 films using multistep, lengthy and not always reproducible sol-gel procedures, to use commercially available nanotitania materials and produce reproducible films faster that exhibit all the properties that make TiO2 films ideal for protein immobilization. Although these materials are formulated primarily for dye-sensitized solar cell applications, in this study we found out that protein immobilization is facile and remarkably stable on all of them. We also investigated their electrochemical properties by using cyclic voltammetry and spectroelectrochemistry and found out that not only direct reduction of Fe(III)-heme to Fe(II)-heme of immobilized Cyt-c was possible on all films but that the adsorbed protein remained electroactive.

  16. A Facile Method for Synthesizing TiO2 Sea-Urchin-Like Structures and Their Applications in Solar Energy Harvesting

    International Nuclear Information System (INIS)

    Wang Wen-Hui; Xu Hong-Xing; Wang Wen-Zhong

    2011-01-01

    We present a new method to prepare TiO 2 sea-urchin-like structures, which involves the initial formation of tubular nanostructures and subsequent self-assembly of the nanotubes into micrometer-scale sea-urchin-like structures. We also investigate the important role of alkali aqueous conditions in the preparation of TiO 2 sea-urchin-like structures. This facile and cost-effective approach provides a new route for the preparation of self-assembled TiO 2 structures. In addition, the performance of the as-synthesized TiO 2 sea-urchin-like structures as the active layer of an efficient solar energy harvester is also studied and discussed. (cross-disciplinary physics and related areas of science and technology)

  17. 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

  18. Comparison of TiO2 photocatalysis, electrochemically assisted Fenton reaction and direct electrochemistry for simulation of phase I metabolism reactions of drugs

    NARCIS (Netherlands)

    Ruokolainen, Miina; Gül, Turan; Permentier, Hjalmar; Sikanen, Tiina; Kostiainen, Risto; Kotiaho, Tapio

    2016-01-01

    The feasibility of titanium dioxide (TiO2) photocatalysis, electrochemically assisted Fenton reaction (EC-Fenton) and direct electrochemical oxidation (EC) for simulation of phase I metabolism of drugs was studied by comparing the reaction products of buspirone, promazine, testosterone and

  19. Simply synthesized TiO2 nanorods as an effective scattering layer for quantum dot sensitized solar cells

    International Nuclear Information System (INIS)

    Samadpour, Mahmoud; Zad, Azam Iraji; Molaei, Mehdi

    2014-01-01

    TiO 2 nanorod layers are synthesized by simple chemical oxidation of Ti substrates. Diffuse reflectance spectroscopy measurements show effective light scattering properties originating from nanorods with length scales on the order of one micron. The films are sensitized with CdSe quantum dots (QDs) by successive ionic layer adsorption and reaction (SILAR) and integrated as a photoanode in quantum dot sensitized solar cells (QDSCs). Incorporating nanorods in photoanode structures provided 4- to 8-fold enhancement in light scattering, which leads to a high power conversion efficiency, 3.03% (V oc = 497 mV, J sc = 11.32 mA/cm 2 , FF = 0.54), in optimized structures. High efficiency can be obtained just by tuning the photoanode structure without further treatments, which will make this system a promising nanostructure for efficient quantum dot sensitized solar cells. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  20. Crystal growth and design of a facile synthesized uniform single crystalline football-like anatase TiO2 microspheres with exposed {0 0 1} facets

    International Nuclear Information System (INIS)

    Liu, Bitao; Jin, Chunhua; Ju, Yue; Peng, Lingling; Tian, Liangliang; Wang, Jinbiao; Zhang, Tiejun

    2014-01-01

    Graphical abstract: - Highlights: • Football-like TiO 2 synthesized by a facile hydrothermal method. • The formation mechanism of football-like TiO 2 was investigated. • The DSSC efficiency assembled by football-like TiO 2 is 23.3% higher than P25. - Abstract: Uniform football-like anatase TiO 2 particles exposed by {0 0 1} facets were successfully synthesized by an environment-friendly, facile and low-temperature hydrothermal method in water solution without any additional capping agent. The crystallographic structure and the growth mechanism of anatase TiO 2 particles were investigated systematically by X-ray diffraction pattern (XRD), field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectra (XPS), respectively. The formation mechanism of football-like anatase TiO 2 particles exposed by {0 0 1} facets is investigated. It was found that there existed a selective adsorption of F − ions on different facets by analyzed with the density functional theory (DFT) computer simulation results, and it would lead to a selective nucleation and crystal growth of anatase football-like TiO 2 particles. Additionally, this type of exposed {0 0 1} facets football-like TiO 2 microspheres were used as a scattering overlayer on a transparent P25 film for fabrication of photoanodes for dye-sensitized solar cells (DSSCs). The results showed that an overall light conversion efficiency of this film was 6.31%, which is higher than that of the overall efficiency (5.13%) obtained from the P25 photoanode owing to the superior light scattering effect of microspheres and excellent light reflecting ability of the mirror-like plane {0 0 1} facets

  1. Enhancing the electrochemical performance of commercial TiO2 by eliminating sulfate radicals and coating carbon

    International Nuclear Information System (INIS)

    Wang, Li-Ying; Wu, Yan; Han, Jian-Ping; Zhang, Bo; Bai, Xue; Qi, Yong-Xin; Lun, Ning; Cao, Yu-Mei; Bai, Yu-Jun

    2017-01-01

    Highlights: •Commercial TiO 2 (c-TiO 2 ) exhibits poor electrochemical performance. •The performance of c-TiO 2 is improved by coating carbon at temperatures above 750 °C. •The removal of SO 4 2− and formation of carbon coating are responsible for the enhanced performance. -- Abstract: Despite the low price of commercial TiO 2 (c-TiO 2 ), the poor electrochemical performance restricts its practical application in Li-ion batteries, so clarifying the reasons and taking appropriate measures to improve the performance are of great significance. Herein, c-TiO 2 was coated with carbon at 600 and 750 °C using glucose as the carbon source. The product obtained at 750 °C exhibits markedly enhanced reversible capacities and outstanding rate performance compared to that obtained at 600 °C. In terms of the comparative experiments and detailed characterizations by several techniques, the SO 4 2− remained in the c-TiO 2 is the dominant impurity affecting the electrochemical performance mostly. The thorough decomposition of SO 4 2− at 750 °C and the formation of carbon coating give rise to the enhanced electronic and ionic conductivities of the c-TiO 2 , and thus are responsible for the significant improvement in the electrochemical performance. The easy fabrication and the low cost of the raw materials enable the carbon-coated c-TiO 2 to industrially apply in the LIBs.

  2. Studies on the Fe3+ Doping Effect on Structural, Optical and Catalytic Properties of Hydrothermally Synthesized TiO2 Photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Kamble, Ravi [Department of Physics, Jaysingpur College, Jaysingpur-416101, India; Sabale, Sandip [P.G. Department of Chemistry, Jaysingpur College, Jaysingpur-416101, Maharashtra, India; Chikode, Prashant [Department of Physics, Jaysingpur College, Jaysingpur-416101, India; Puri, Vijaya [Department of Physics, Shivaji University, Kolhapur-416004, India; Yu, Xiao-Ying [Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory (PNNL), Richland, WA 99352, United States; Mahajan, Smita [Department of Physics, Jaysingpur College, Jaysingpur-416101, India

    2017-08-01

    Pure TiO2 and Fe3+-TiO2 nanoparticles have been prepared by simple hydrothermal method with different Fe3+ concentrations. The synthesized nanoparticles are analysed to determine its structural, optical, morphological and compositional properties using X-ray diffraction, Raman, UV-DRS, photoluminescence, Mossbauer, XPS, TEM and SEM/EDS. The EDS micrograph confirms the existence of Fe3+ atoms in the TiO2 matrix with 0.85, 1.52 and 1.87 weight percent. The crystallite size and band gap decrease with increase in Fe3+concentration. The average particle size obtained from TEM is 7-11 nm which is in good agreement with XRD results. Raman bands at 640 cm-1, 517 cm-1 and 398 cm-1 further confirm pure phase anatase in all samples. XPS shows the proper substitutions of few sites of Ti4+ ions by Fe3+ ions in the TiO2 host lattice. The intensity of PL spectra for Fe3+-TiO2 shows a gradual decrease in the peak intensity with increasing Fe3+ concentration in TiO2, and it indicates lower recombination rate as Fe3+ ions increases. These nanoparticles are further studied for its photocatalytic activities using malachite green dye under UV light, visible light and sunlight.

  3. Inverted organic solar cells with solvothermal synthesized vanadium-doped TiO2 thin films as efficient electron transport layer

    Institute of Scientific and Technical Information of China (English)

    Mehdi Ahmadi; Sajjad Rashidi Dafeh; Samaneh Ghazanfarpour; Mohammad Khanzadeh

    2017-01-01

    We investigated the effects of using different thicknesses of pure and vanadium-doped thin films of TiO2 as the electron transport layer in the inverted configuration of organic photovoltaic cells based on poly (3-hexylthiophene) P3HT:[6-6] phenyl-(6) butyric acid methyl ester (PCBM).1% vanadium-doped TiO2 nanoparticles were synthesized via the solvothermal method.Crystalline structure,morphology,and optical properties of pure and vanadium-doped TiO2 thin films were studied by different techniques such as x-ray diffraction,scanning electron microscopy,transmittance electron microscopy,and UV-visible transmission spectrum.The doctor blade method which is compatible with roll-2-roll printing was used for deposition of pure and vanadium-doped TiO2 thin films with thicknesses of 30 nm and 60 nm.The final results revealed that the best thickness of TiO2 thin films for our fabricated cells was 30 nm.The cell with vanadium-doped TiO2 thin film showed slightly higher power conversion efficiency and great Jsc of 10.7 mA/cm2 compared with its pure counterpart.In the cells using 60 nm pure and vanadium-doped TiO2 layers,the cell using the doped layer showed much higher efficiency.It is remarkable that the extemal quantum efficiency of vanadium-doped TiO2 thin film was better in all wavelengths.

  4. Constructing superhydrophobic WO3@TiO2 nanoflake surface beyond amorphous alloy against electrochemical corrosion on iron steel

    Science.gov (United States)

    Yu, S. Q.; Ling, Y. H.; Wang, R. G.; Zhang, J.; Qin, F.; Zhang, Z. J.

    2018-04-01

    To eliminate harmful localized corrosion, a new approach by constructing superhydrophobic WO3@TiO2 hierarchical nanoflake surface beyond FeW amorphous alloy formed on stainless steel was proposed. Facile dealloying and liquid deposition was employed at low temperature to form a nanostructured layer composing inner WO3 nanoflakes coated with TiO2 nanoparticles (NPs) layer. After further deposition of PFDS on nanoflakes, the contact angle reached 162° while the corrosion potential showed a negative shift of 230 mV under illumination, resulting in high corrosion resistance in 3.5 wt% NaCl solution. The tradeoff between superhydrophobic surface and photo-electro response was investigated. It was found that this surface feature makes 316 SS be immune to localized corrosion and a pronounced photo-induced process of electron storage/release as well as the stability of the functional layer were detected with or without illumination, and the mechanism behind this may be related to the increase of surface potential due to water repellence and the delayed cathodic protection of semiconducting coating derived mainly from the valence state changes of WO3. This study demonstrates a simple and low-cost electrochemical approach for protection of steel and novel means to produce superhydrophobic surface and cathodic protection with controllable electron storage/release on engineering scale.

  5. Optical and morphological properties of ZnO- and TiO2-derived nanostructures synthesized via a microwave-assisted hydrothermal method

    CSIR Research Space (South Africa)

    Moloto, N

    2012-01-01

    Full Text Available Corporation International Journal of Photoenergy Volume 2012, Article ID 189069, 6 pages doi:10.1155/2012/189069 Research Article Optical and Morphological Properties of ZnO- and TiO2-Derived Nanostructures Synthesized via a Microwave... International Journal of Photoenergy the sol-gel, hydrothermal process, and pulse laser deposition [22?24]. Although the sol-gel method is widely accepted for the preparation of both ZnO and TiO2 nanostructures, the calcinations process is essential and can...

  6. Study of phase development and thermal stability in as synthesized TiO2 nanoparticles by laser pyrolysis: ethylene uptake and oxygen enrichment

    Science.gov (United States)

    Ilie, Alina Georgiana; Scarisoreanu, Monica; Dutu, Elena; Dumitrache, Florian; Banici, Ana-Maria; Fleaca, Claudiu Teodor; Vasile, Eugenia; Mihailescu, Ion

    2018-01-01

    Laser pyrolysis has proven a viable and trustworthy method of TiO2 nanoparticles fabrication, ensuring good quality and wide variety of nanoparticle morphologies and sizes. This work is aimed to phase control, experimentally studied, by parameter modulation, during one step laser pyrolysis synthesis or in combination with thermal annealing. High phase purity anatase and rutile TiO2 nanoparticles, oxygen abundant, are synthesized from TiCl4 and C2H4 gas mixtures, in the presence of air as oxygen donor, under CO2 laser radiation. The nano-titania samples are analyzed by X-ray Diffraction, EDAX, TEM and Raman spectroscopy and reveal good phase stability and distinct morphology. This study extends the method applicability onto rutile majoritarian TiO2 synthesis and generation of thermally stable anatase titania, a well-known catalyst.

  7. TiO2 film decorated with highly dispersed polyoxometalate nanoparticles synthesized by micelle directed method for the efficiency enhancement of dye-sensitized solar cells

    Science.gov (United States)

    He, Lifei; Chen, Li; Zhao, Yue; Chen, Weilin; Shan, Chunhui; Su, Zhongmin; Wang, Enbo

    2016-10-01

    In this work, two kinds of polyoxometalate (POM) nanoparticles with controlled shapes and structures were synthesized by micelle directed method and then composited with TiO2 via calcination to remove the surfactants owing to the excellent electronic storage and transmission ability of POM, finally obtaining two kinds of TiO2 composites with highly dispersed and small-sized POM nanoparticles (∼1 nm). The TiO2 composites were then induced into the photoanodes of dye-sensitized (N719) solar cells (DSSCs). The separation of electron-holes becomes more favorable due to the nanostructure and high dispersion of POM which provide more active sites than pure POM tending to agglomeration. The TiO2 composite photoanodes finally yielded the power conversion efficiency (PCE) of 8.4% and 8.2%, respectively, which were 42% and 39% higher than the pristine TiO2 based anodes. In addition, the mechanisms of POM in DSSC are proposed.

  8. Comparison of TiO2 photocatalysis, electrochemically assisted Fenton reaction and direct electrochemistry for simulation of phase I metabolism reactions of drugs.

    Science.gov (United States)

    Ruokolainen, Miina; Gul, Turan; Permentier, Hjalmar; Sikanen, Tiina; Kostiainen, Risto; Kotiaho, Tapio

    2016-02-15

    The feasibility of titanium dioxide (TiO2) photocatalysis, electrochemically assisted Fenton reaction (EC-Fenton) and direct electrochemical oxidation (EC) for simulation of phase I metabolism of drugs was studied by comparing the reaction products of buspirone, promazine, testosterone and 7-ethoxycoumarin with phase I metabolites of the same compounds produced in vitro by human liver microsomes (HLM). Reaction products were analysed by UHPLC-MS. TiO2 photocatalysis simulated the in vitro phase I metabolism in HLM more comprehensively than did EC-Fenton or EC. Even though TiO2 photocatalysis, EC-Fenton and EC do not allow comprehensive prediction of phase I metabolism, all three methods produce several important metabolites without the need for demanding purification steps to remove the biological matrix. Importantly, TiO2 photocatalysis produces aliphatic and aromatic hydroxylation products where direct EC fails. Furthermore, TiO2 photocatalysis is an extremely rapid, simple and inexpensive way to generate oxidation products in a clean matrix and the reaction can be simply initiated and quenched by switching the UV lamp on/off. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. TiO2/PbS/ZnS heterostructure for panchromatic quantum dot sensitized solar cells synthesized by wet chemical route

    Science.gov (United States)

    Bhat, T. S.; Mali, S. S.; Sheikh, A. D.; Korade, S. D.; Pawar, K. K.; Hong, C. K.; Kim, J. H.; Patil, P. S.

    2017-11-01

    So far we developed the efficient photoelectrodes which can harness the UV as well as the visible regime of the solar spectrum effectively. In order to exploit a maximum portion of solar spectrum, it is necessary to study the synergistic effect of a photoelectrode comprising UV and visible radiations absorbing materials. Present research work highlights the efforts to study the synchronized effect of TiO2 and PbS on the power conversion efficiency of quantum dot sensitized solar cell (QDSSC). A cascade structure of TiO2/PbS/ZnS QDSSC is achieved to enhance the photoconversion efficiency of TiO2/PbS system by incorporating a surface passivation layer of ZnS which avoids the recombination of charge carriers. A QDSSC is fabricated using a simple and cost-effective technique such as hydrothermally grown TiO2 nanorod arrays decorated with PbS and ZnS using successive ionic layer adsorption and reaction (SILAR) method. Synthesized electrode materials are characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), High resolution-transmission electron microscopy (TEM), STEM-EDS mapping, optical and solar cell performances. Phase formation of TiO2, PbS and ZnS get confirmed from the XPS study. FE-SEM images of the photoelectrode show uniform coverage of PbS QDs onto the TiO2 nanorods which increases with increasing number of SILAR cycles. The ZnS layer not only improves the charge transport but also reduces the photocorrosion of lead chalcogenides in the presence of a liquid electrolyte. Finally, the photoelectrochemical (PEC) study is carried out using an optimized photoanode comprising TiO2/PbS/ZnS assembly. Under AM 1.5G illumination the TiO2/PbS/ZnS QDSSC photoelectrode shows 4.08 mA/cm2 short circuit current density in a polysulfide electrolyte which is higher than that of a bare TiO2 nanorod array.

  10. Effect of ambient pressure on the crystalline phase of nano TiO2 particles synthesized by a dc thermal plasma reactor

    International Nuclear Information System (INIS)

    Banerjee, I.; Karmakar, Soumen; Kulkarni, Naveen V.; Nawale, Ashok B.; Mathe, V. L.; Das, A. K.; Bhoraskar, S. V.

    2010-01-01

    The synthesis of nanoparticles of titanium dioxide (TiO 2 ) with varying percentages of anatase and rutile phases is reported. This was achieved by controlling the operating pressure in a transferred-arc, direct current thermal plasma reactor in which titanium vapors are evaporated, and then exposed to ambient oxygen. The average particle size remained around 15 nm in each case. The crystalline structure of the as-synthesized nanoparticles of TiO 2 was studied with X-ray diffraction analysis; whereas the particle morphology was investigated with the help of transmission electron microscopy. The precursor species responsible for the growth of these nanoparticles was studied with the help of optical emission spectroscopy. As inferred from the X-ray diffraction analysis, the relative abundance of anatase TiO 2 was found to be dominant when synthesized at 760 Torr, and the same showed a decreasing trend with decreasing chamber pressure. The study also reveals that anatase TiO 2 is a more effective photocatalytic agent in degrading methylene blue by comparison to its rutile phase.

  11. Enhancement in photo-electrochemical efficiency by reducing recombination rate in branched TiO2 nanotube array on functionalizing with ZnO micro crystals

    Science.gov (United States)

    Boda, Muzaffar Ahmad; Ashraf Shah, Mohammad

    2018-06-01

    In this study, branched TiO2 nanotube array were fabricated through electrochemical anodization process at constant voltage using third generation electrolyte. On account of morphological advantage, these nanotubes shows significant enhancement in photo-electrochemical property than compact or conventional titania nanotube array. However, their photo-electrochemical efficiency intensifies on coating with ZnO micro-crystals. ZnO coated branched TiO2 nanotube array shows a photocurrent density of 27.8 mA cm‑2 which is 1.55 times the photocurrent density (17.2 mA cm‑2) shown by bare branched titania nanotubes. The significant enhancement in photocurrent density shown by the resulting ZnO/TiO2 hybrid structure is attributed to suppression in electron–hole recombination phenomenon by offering smooth pathway to photo generated excitons on account of staggered band edge positions in individual semiconductors.

  12. Characteristics and properties of a novel in situ method of synthesizing mesoporous TiO2 nanopowders by a simple coprecipitation process without adding surfactant

    International Nuclear Information System (INIS)

    Yeh, Shang-Wei; Ko, Horng-Huey; Chiang, Hsiu-Mei; Chen, Yen-Ling; Lee, Jian-Hong; Wen, Chiu-Ming; Wang, Moo-Chin

    2014-01-01

    Highlights: • The TiO 2 precursor powder contained anatase and 19.5% NH 4 Cl. • Mesoporous anatase TiO 2 nanopowders were successfully synthesized. • Uncalcined precursor powder contained the phases of type I NH 4 Cl and anatase TiO 2 . • Anatase size increases from 3.3 to 14.3 nm when calcined at 473–773 K for 2 h. • The average pore size between 3.80 and 14.0 nm when calcined between 473 and 773 K. - Abstract: In situ synthesis of mesoporous TiO 2 nanopowders using titanium tetrachloride (TiCl 4 ) and NH 4 OH as initial materials has been successfully fabricated by a coprecipitation process without the addition of surfactant. Characteristics and properties of the mesoporous TiO 2 nanopowders were investigated using differential scanning calorimetry/thermogravimetry (DSC/TG), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) and Barrent–Joyner–Halenda (BJH) analyses, transmission electron microscopy (TEM), selected area electron diffraction (SAED) and high resolution TEM (HRTEM). The results of TG and XRD showed that the NH 4 Cl decomposed between 513 and 673 K. XRD results showed that the anatase TiO 2 only contained a single phase when the calcination temperature of the precursor powder was less than 673 K. Whereas phases of anatase and rutile TiO 2 coexist after calcining at 773 K for 2 h. The crystalline size of the anatase and rutile TiO 2 was 14.3 and 26.6 nm, respectively, when the precursor powder was calcined at 773 K for 2 h. The BET and BJH results showed a significant increase in surface area and pore volumes when the NH 4 Cl was completely decomposed. The maximum values of BET specific surface area and volume were 172.8 m 2 /g and 0.392 cm 3 /g, respectively. The average pore sizes when calcination was at 473 and 773 K for 2 h were 3.8 and 14.0 nm, respectively

  13. Analysis of X-ray diffraction of the titanium dioxide (TiO_2) synthesized by the Pechini Method for application in heterogeneous photocatalysis processes

    International Nuclear Information System (INIS)

    Oliveira, P.L.; Araujo, D.S.; Costa, A.C.F.M.; Oliveira, L.S.C.

    2016-01-01

    Titanium dioxide (TiO_2) is a polymorph commonly applied to heterogeneous photocatalysis processes for being relatively inexpensive and photo - stable. It is usually found in three different crystalline phases (anatase, rutile and brookite), which directly interfere in their photocatalytic efficiency. Therefore, this study aimed to investigate the obtainment of TiO_2 by Pechini method in different conditions for application in the heterogeneous photocatalysis process. For this purpose, it was evaluated by analysis of X-ray diffraction (XRD ) the behavior of TiO_2 materials synthesized in proportions of 2:1 and 3:1 (titanium isopropoxide/citric acid), pyrolyzed at 300°C/3h and 400°C /h and calcined at 400°C and 500°C/1h. The results revealed that the TiO_2 samples produced in the ratio of 2:1 and 3:1 isopropoxide/citric acid and calcined at 500°C/h presented the best results. (author)

  14. Well-defined copolymers synthesized by RAFT polymerization as effective modifiers to enhance the photocatalytic performance of TiO_2

    International Nuclear Information System (INIS)

    Vasilaki, E.; Kaliva, M.; Katsarakis, N.; Vamvakaki, M.

    2017-01-01

    Highlights: • Well-defined, random functional copolymers were synthesized by RAFT polymerization. • Novel TiO_2 particles in-situ modified with copolymers were synthesized. • The hybrid catalysts exhibited reduced aggregation and particle size. • The photocatalytic removal of methylene blue was higher for the hybrid catalysts. - Αbstract: The enhancement of the photocatalytic performance of anatase TiO_2 nanoparticles is demonstrated by a facile route, involving their in-situ surface modification with preformed polymer chains. Random copolymers of poly(ethylene glycol) methyl ether acrylate-co-methacrylic acid (PEGA-co-MAA) or poly(ethylene glycol) methyl ether acrylate-co-dopamine methacrylamide (PEGA-co-DMA) were synthesized by reversible addition−fragmentation chain-transfer (RAFT) polymerization and were bound onto the surface of anatase titania nanoparticles via the “grafting to” method. The hybrid nanocatalysts were characterized by fourier transform infrared spectroscopy, zeta-potential measurements, X-ray powder diffraction, thermogravimetric analysis and transmission electron microscopy. Their photocatalytic performance was evaluated by the decoloration of methylene blue (MB) dye in aqueous media under UV–vis light irradiation. The enhanced photoactivity and reusability of the polymer modified photocatalysts compared to that of bare TiO_2 nanoparticles was attributed to their improved dispersability and colloidal stability, the smaller particle size that leads to a larger surface area and the increased adsorption capacity of the dye onto the polymer modified nanoparticles.

  15. Short-term memory of TiO2-based electrochemical capacitors: empirical analysis with adoption of a sliding threshold

    International Nuclear Information System (INIS)

    Lim, Hyungkwang; Kim, Inho; Kim, Jin-Sang; Jeong, Doo Seok; Seong Hwang, Cheol

    2013-01-01

    Chemical synapses are important components of the large-scaled neural network in the hippocampus of the mammalian brain, and a change in their weight is thought to be in charge of learning and memory. Thus, the realization of artificial chemical synapses is of crucial importance in achieving artificial neural networks emulating the brain’s functionalities to some extent. This kind of research is often referred to as neuromorphic engineering. In this study, we report short-term memory behaviours of electrochemical capacitors (ECs) utilizing TiO 2 mixed ionic–electronic conductor and various reactive electrode materials e.g. Ti, Ni, and Cr. By experiments, it turned out that the potentiation behaviours did not represent unlimited growth of synaptic weight. Instead, the behaviours exhibited limited synaptic weight growth that can be understood by means of an empirical equation similar to the Bienenstock–Cooper–Munro rule, employing a sliding threshold. The observed potentiation behaviours were analysed using the empirical equation and the differences between the different ECs were parameterized. (paper)

  16. The influence of TiO2 and aeration on the kinetics of electrochemical oxidation of phenol in packed bed reactor

    International Nuclear Information System (INIS)

    Wang Lizhang; Zhao Yuemin; Fu Jianfeng

    2008-01-01

    The electrochemical oxidation of phenolic wastewater in a lab-scale reactor, packed into granular activated carbon (GAC) with Ti/SnO 2 anodes and stainless steel cathodes, was interpreted in this study. GAC saturated rapidly if it was only used as sorbent, but application of suitable electric energy for the system simultaneously could recover the adsorption ability of GAC and maintain the continuous running effectively. The titanium dioxide (TiO 2 ) as catalyst and airflow were also applied to the electrochemical reactor to examine the enhancement for phenol oxidation process. Results revealed that the electrochemical degradation of phenol could be reasonably described by first-order kinetics. In addition, it was illustrated that acid region, increased voltage, more dosage of TiO 2 and higher aeration intensity were all beneficial parameters for phenol oxidation rates. By inspecting the relationship between the rate constants (k) and influencing factors, respectively, an overall kinetic model for phenol oxidation was proposed. The kinetics obtained from the experiments under corresponding electrochemical conditions could provide an accurate estimation of phenol concentration effluent and better design of the packed bed reactor

  17. The electrochemical behavior of Co(TPTZ)2 complex on different carbon based electrodes modified with TiO2 nanoparticles

    International Nuclear Information System (INIS)

    Ortaboy, Sinem; Atun, Gülten

    2015-01-01

    Electrochemical behavior of cobalt (II) complex with the N-donor ligand 2,2′-bipyridyl-1,3,5-tripyridyl-s-triazine (TPTZ) was investigated to elucidate the electron-proton transfer mechanisms. The electrochemical response of the complex was studied using square-wave voltammetry (SWV) and electrochemical impedance spectroscopy (EIS) techniques. A conventional three-electrode system, consisting of glassy carbon (GCE), TiO 2 modified glassy carbon (T/GCE), carbon paste (CPE) and TiO 2 modified carbon paste (T/CPE) working electrodes were employed. The ligand/metal ratio and stability constant of the complex as well as the mechanisms of the electrode processes were elucidated by examining the effects of pH, ligand concentration and frequency on the voltammograms. The EIS results indicated that the samples modified with TiO 2 had the higher charge transfer resistance than that of the bare electrodes and also suggested that the electroactivity of the electrode surfaces increased in the following order, T/CPE > CPE > T/GCE > GCE. The surface morphology of the working electrodes was also characterized by atomic force microscopy (AFM). The values of surface roughness parameters were found to be consistent with the results obtained by EIS experiments. - Graphical abstract: Schematic illustration of the experimental process. - Highlights: • Electrochemical behavior of Co(TPTZ) 2 complex studied by SWV and EIS techniques. • GCE, CPE T/GCE and T/CPE were used as working electrodes for comparative studies. • The surface morphologies of the electrodes were characterized by AFM. • Mechanisms were proposed from the effects of pH, ligand concentration and frequency. • EIS and morphologic relationships of the surfaces were established successfully

  18. Optimizing Thermoelectric Properties of In Situ Plasma-Spray-Synthesized Sub-stoichiometric TiO2-x Deposits

    Science.gov (United States)

    Lee, Hwasoo; Seshadri, Ramachandran Chidambaram; Pala, Zdenek; Sampath, Sanjay

    2018-06-01

    In this article, an attempt has been made to relate the thermoelectric properties of thermal spray deposits of sub-stoichiometric titania to process-induced phase and microstructural variances. The TiO2-x deposits were formed through the in situ reaction of the TiO1.9 or TiO1.7 feedstock within the high-temperature plasma flame and manipulated via varying the amounts of hydrogen fed into in the thermal plasma. Changes in the flow rates of H2 in the plasma plume greatly affected the in-flight particle behavior and composition of the deposits. For reference, a high-velocity oxy-fuel spray torch was also used to deposit the two varieties of feedstocks. Refinements to the representation of the in-flight particle characteristics derived via single particle and ensemble diagnostic methods are proposed using the group parameters (melting index and kinetic energy). The results show that depending on the value of the melting index, there is an inverse proportional relationship between electrical conductivity and Seebeck coefficient, whereas thermal conductivity has a directly proportional relationship with the electrical conductivity. Retention of the original phase and reduced decomposition is beneficial to retain the high Seebeck coefficient or the high electrical conductivity in the TiO2 system.

  19. TiO2-coated Hollow Glass Microspheres with Superhydrophobic and High IR-reflective Properties Synthesized by a Soft-chemistry Method.

    Science.gov (United States)

    Wong, Yinting; Zhong, Dan; Song, Aotian; Hu, Yan

    2017-04-26

    This manuscript proposes a soft-chemistry method to develop superhydrophobic and highly IR-reflective hollow glass microspheres (HGM). The anatase TiO2 and a superhydrophobic agent were coated on the HGM surface in one step. TBT and PFOTES were selected as the Ti source and the superhydrophobic agent, respectively. They were both coated on the HGM, and after the hydrothermal process, the TBT turned to anatase TiO2. In this way, a PFOTES/TiO2-coated HGM (MCHGM) was prepared. For comparison, PFOTES single-coated HGM (F-SCHGM) and TiO2 single-coated HGM (Ti-SCHGM) were synthesized as well. The PFOTES and TiO2 coatings on the HGM surface were demonstrated through X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive detector (EDS) characterizations. The MCHGM showed a higher contact angle (153°) but a lower sliding angle (16°) than F-SCHGM, with a contact angle of 141.2° and a sliding angle of 67°. In addition, both Ti-SCHGM and MCHGM displayed similar IR reflectivity values, which were about 5.8% higher than the original HGM and F-SCHGM. Also, the PFOTES coating barely changed the thermal conductivity. Therefore, F-SCHGM, with a thermal conductivity of 0.0479 W/(m·K), was quite like the original HGM, which was 0.0475 W/(m·K). MCHGM and Ti-SCHGM were also similar. Their thermal conductivity values were 0.0543 W/(m·K) and 0.0543 W/(m·K), respectively. The TiO2 coating slightly increased the thermal conductivity, but with the increase in reflectivity, the overall heat-insulation property was enhanced. Finally, since the IR-reflecting property is provided by the HGM coating, if the coating is fouled, the reflectivity decreases. Therefore, with the superhydrophobic coating, the surface is protected from fouling, and its lifetime is also prolonged.

  20. Computational Fluid Dynamics (CFD Analysis of Phthalic Anhydride’s Yield Using Lab Synthesized and Commercially Available (V2O5/TiO2 Catalyst

    Directory of Open Access Journals (Sweden)

    A. Sarosh

    2018-04-01

    Full Text Available V2O5/TiO2 is an important catalyst used in many industrial reactions like selective oxidation of o-xylene to phthalic anhydride, selective catalytic reduction of NOx, selective oxidation of alkanes, etc. The partial oxidation of o-xylene to synthesize phthalic anhydride is an exothermic reaction and leaves hot spots on the catalyst’s surface. The yield of phthalic anhydride strongly depends on the activity and stability of the catalyst. In this work, a computational fluid dynamics (CFD analysis has been conducted to compare the yield of lab prepared catalyst with the commercially used catalyst. This work is first attempt to simulate V2O5/TiO2 catalyst for cracking heavy hydrocarbons in the petrochemical industry using k- ε turbulence and species transport models in CFD. The results obtained are in the form of scaled residuals, area-weighted average, and contours of pressure and temperature. Simulation results of lab synthesized and commercially used catalysts, applying finite volume method (FVM are compared, which emphasize the scope of CFD modeling in the catalytic cracking process of petrochemical industry.

  1. Electrochemical Performance of a Carbon Nanotube/La-Doped TiO2 Nanocomposite and its Use for Preparation of an Electrochemical Nicotinic Acid Sensor

    Directory of Open Access Journals (Sweden)

    Hanxing Liu

    2008-11-01

    Full Text Available A carbon nanotube/La-doped TiO2 (La-TiO2 nanocomposite (CLTN was prepared by a procedure similar to a complex/adsorption process. Scanning electron microscopy (SEM images show that the La-TiO2 distributes on the carbon nanotube walls. The CLTN was mixed with paraffin to form a CLTN paste for the CLTN paste electrode (CLTNPE. The electrochemical characteristics of CLTNPE were compared with that of conventional carbon electrodes such as the carbon paste electrode (CPE and glass carbon electrode (GC. The CLTNPE exhibits electrochemical activity and was used to investigate the electrochemistry of nicotinic acid (NA. The modified electrode has a strong electrocatalytic effect on the redox of NA. The cyclic voltammetry (CV redox potential of NA at the CLTNPE is 320 mV. The oxidation process of NA on the CLTNPE is pH dependent. A sensitive chronoamperometric response for NA was obtained covering a linear range from 1.0×10-6 mol·L-1 to 1.2×10-4 mol·L-1, with a detection limit of 2.7×10-7 mol·L-1. The NA sensor displays a remarkable sensitivity and stability. The mean recovery of NA in the human urine is 101.8%, with a mean variation coefficient (RSD of 2.6%.

  2. The Effect of Normal Force on Tribocorrosion Behaviour of Ti-10Zr Alloy and Porous TiO2-ZrO2 Thin Film Electrochemical Formed

    Science.gov (United States)

    Dănăilă, E.; Benea, L.

    2017-06-01

    The tribocorrosion behaviour of Ti-10Zr alloy and porous TiO2-ZrO2 thin film electrochemical formed on Ti-10Zr alloy was evaluated in Fusayama-Mayer artificial saliva solution. Tribocorrosion experiments were performed using a unidirectional pin-on-disc experimental set-up which was mechanically and electrochemically instrumented, under various solicitation conditions. The effect of applied normal force on tribocorrosion performance of the tested materials was determined. Open circuit potential (OCP) measurements performed before, during and after sliding tests were applied in order to determine the tribocorrosion degradation. The applied normal force was found to greatly affect the potential during tribocorrosion experiments, an increase in the normal force inducing a decrease in potential accelerating the depassivation of the materials studied. The results show a decrease in friction coefficient with gradually increasing the normal load. It was proved that the porous TiO2-ZrO2 thin film electrochemical formed on Ti-10Zr alloy lead to an improvement of tribocorrosion resistance compared to non-anodized Ti-10Zr alloy intended for biomedical applications.

  3. Dielectric and electrochemical properties through-thickness mapping on extremely thick plasma sprayed TiO2

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Sedláček, J.; Pala, Zdeněk

    2016-01-01

    Roč. 42, č. 6 (2016), s. 7183-7191 ISSN 0272-8842 Institutional support: RVO:61389021 Keywords : Electrical properties * TiO2 * Plasma spraying * Annealing * Microstructure Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 2.986, year: 2016 http://www.sciencedirect.com/science/article/pii/S0272884216001395

  4. Electrochemical grafting of TiO2-based photo-anodes and its effect in dye-sensitized solar cells

    DEFF Research Database (Denmark)

    Lund, Torben; Phuong, Nguyen Tuyet; Ruhland, Thomas Gerhard Aloysius

    2015-01-01

    We demonstrate that hydroxyl-groups which are located on the surfaces of mesoporous metal oxides (in particular sintered layers of F-doped tin oxide (FTO) and TiO2 on glass plates) are capable of undergoing reactions with 4-nitrobenzene radicals. The highly reactive benzene radicals are generated...

  5. Effect of sonochemical synthesized TiO2 nanoparticles and coagulation bath temperature on morphology, thermal stability and pure water flux of asymmetric cellulose acetate membranes prepared via phase inversion method

    Directory of Open Access Journals (Sweden)

    Abedini Reza

    2012-01-01

    Full Text Available In this study, asymmetric pure CA and CA/ TiO2 composite membranes were prepared via phase inversion by dispersing TiO2 nanopaticles in the CA casting solutions induced by immersion precipitation in water coagulation bath. TiO2 nanoparticles, which were synthesized by the sonochemical method, were added into the casting solution with different concentrations. Effects of TiO2 nanoparticles concentration (0 wt. %, 5wt.%, 10wt.%, 15wt.%, 20wt.% and 25wt.% and coagulation bath temperature (CBT= 25°C, 50°C and 75°C on morphology, thermal stability and pure water flux (PWF of the prepared membranes were studied and discussed. Increasing TiO2 concentration in the casting solution film along with higher CBT resulted in increasing the membrane thickness, water content (WC, membrane porosity and pure water flux (PWF, also these changes facilitate macrovoids formation. Thermal gravimetric analysis (TGA shows that thermal stability of the composite membranes were improved by the addition of TiO2 nanopaticles. Also TGA results indicated that increasing CBT in each TiO2 concentration leads to the decreasing of decomposition temperature (Td of hybrid membranes.

  6. Investigation of the temperature effect on electrochemical behaviors of TiO2 for gel type valve regulated lead-acid batteries

    Directory of Open Access Journals (Sweden)

    Metin GENÇTEN

    2016-12-01

    Full Text Available In this study, the effect of temperature on the electrochemical behaviors of gel electrolyte systems was investigated for valve regulated lead-acid battery at 0≤ T ≤50 oC. Fumed silica and mixture of fumed silica and TiO2 were used as gel electrolytes. TiO2 has a good combination with fumed silica. They were characterized by cyclic voltammetry, electrochemical impedance spectroscopy and battery tests. The anodic peak currents and redox capacities of the gel electrolytes increased with increasing of temperature. The highest anodic peak current and redox capacity were observed at 30 oC in fumed silica and at 40 oC in fumed silica:TiO2 based gel systems. The solution and charge transfer resistance values decreased in fumed silica:TiO2 gel system by increasing temperature. In battery tests, discharge curves were obtained for each gel system at 0, 25 and 50 oC. The discharge time of mixture gel electrolyte system was higher than that of fumed silica based gel electrolyte at low (0 oC and high (50 oC temperatures. The best performance was obtained in fumed silica based gel electrolyte at 25 oC.

  7. Evaluation of micro-abrasion-corrosion on SiO2-TiO2-ZrO2 coatings synthesized by the sol-gel method

    Science.gov (United States)

    Bautista Ruiz, J.; Aperador, W.; Caballero Gómez, J.

    2016-02-01

    The medical science and the engineering, work to improve the materials used in the manufacture of joint implants, since they have a direct impact on the quality of people life. The surgical interventions are increasing worldwide with a high probability of a second or even a third intervention. Around these circumstances, it was evaluated the behaviour against microabrasion-corrosion phenomena on SiO2 TiO2 ZrO2 coatings, synthesized by the sol-gel method with concentration of the Si/Ti/Zr precursors: 10/70/20 and 10/20/70. The coatings were deposited on AISI 316 LVM stainless steel substrates. The morphological characterization of the wear was made by AFM techniques. It was observed that the coatings with higher levels of titanium have a good response to the phenomena of microabrasion-corrosion.

  8. Coexistence of an anatase/TiO2(B) heterojunction and an exposed (001) facet in TiO2 nanoribbon photocatalysts synthesized via a fluorine-free route and topotactic transformation.

    Science.gov (United States)

    Wang, Changhua; Zhang, Xintong; Liu, Yichun

    2014-05-21

    In this work, we report a novel approach to fabricate hierarchical TiO2 microspheres (HTMS) assembled by ultrathin nanoribbons where an anatase/TiO2(B) heterojunction and high energy facet coexist. The as-adopted approach involves (1) nonaqueous solvothermal treatment of a mixture of tetrabutyl titanate and acetic acid and (2) topotactical transformation into HTMS via thermal annealing. By this approach, the TiO2(B) phase usually synthesized from an alkaline treatment route could be initially formed. Subsequently, phase transition from TiO2(B) to anatase TiO2 occurs upon thermal treatment. It is demonstrated that such phase transition is accompanied by crystallographic orientation along the c-axis of anatase and TiO2(B) crystals, resulting in not only a coherent interface between two phases but also oriented attachment of anatase mesocrystals along the [001] direction, and finally high-energy (001) facet exposure. Interestingly, this work provides an alternative fluorine-free route for the synthesis of TiO2 crystals with high-energy (001) facet exposure. The structural analysis reveals that lattice-match induced topotactic transformation from TiO2(B) to anatase is the sole reason for the (001) facet exposure of anatase TiO2. The photocatalytic test for acetaldehyde decomposition shows that HTMS with anatase/TiO2(B) heterojunction and high-energy (001) facet exhibits superior photocatalytic efficiency compared with the relevant commercial product P25, which can be ascribed to the synergistic effect of large surface area, anatase/TiO2(B) heterojunction as well as high-energy facet exposure.

  9. Coexistence of an anatase/TiO2(B) heterojunction and an exposed (001) facet in TiO2 nanoribbon photocatalysts synthesized via a fluorine-free route and topotactic transformation

    Science.gov (United States)

    Wang, Changhua; Zhang, Xintong; Liu, Yichun

    2014-04-01

    In this work, we report a novel approach to fabricate hierarchical TiO2 microspheres (HTMS) assembled by ultrathin nanoribbons where an anatase/TiO2(B) heterojunction and high energy facet coexist. The as-adopted approach involves (1) nonaqueous solvothermal treatment of a mixture of tetrabutyl titanate and acetic acid and (2) topotactical transformation into HTMS via thermal annealing. By this approach, the TiO2(B) phase usually synthesized from an alkaline treatment route could be initially formed. Subsequently, phase transition from TiO2(B) to anatase TiO2 occurs upon thermal treatment. It is demonstrated that such phase transition is accompanied by crystallographic orientation along the c-axis of anatase and TiO2(B) crystals, resulting in not only a coherent interface between two phases but also oriented attachment of anatase mesocrystals along the [001] direction, and finally high-energy (001) facet exposure. Interestingly, this work provides an alternative fluorine-free route for the synthesis of TiO2 crystals with high-energy (001) facet exposure. The structural analysis reveals that lattice-match induced topotactic transformation from TiO2(B) to anatase is the sole reason for the (001) facet exposure of anatase TiO2. The photocatalytic test for acetaldehyde decomposition shows that HTMS with anatase/TiO2(B) heterojunction and high-energy (001) facet exhibits superior photocatalytic efficiency compared with the relevant commercial product P25, which can be ascribed to the synergistic effect of large surface area, anatase/TiO2(B) heterojunction as well as high-energy facet exposure.

  10. A Cost-Effective Solid-State Approach to Synthesize g-C3N4 Coated TiO2 Nanocomposites with Enhanced Visible Light Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Min Fu

    2013-01-01

    Full Text Available Novel graphitic carbon nitride (g-C3N4 coated TiO2 nanocomposites were prepared by a facile and cost-effective solid-state method by thermal treatment of the mixture of urea and commercial TiO2. Because the C3N4 was dispersed and coated on the TiO2 nanoparticles, the as-prepared g-C3N4/TiO2 nanocomposites showed enhanced absorption and photocatalytic properties in visible light region. The as-prepared g-C3N4 coated TiO2 nanocomposites under 450°C exhibited efficient visible light photocatalytic activity for degradation of aqueous MB due to the increased visible light absorption and enhanced MB adsorption. The g-C3N4 coated TiO2 nanocomposites would have wide applications in both environmental remediation and solar energy conversion.

  11. Enhancement of Ce/Cr Codopant Solubility and Chemical Homogeneity in TiO2 Nanoparticles through Sol-Gel versus Pechini Syntheses.

    Science.gov (United States)

    Chen, Wen-Fan; Mofarah, Sajjad S; Hanaor, Dorian Amir Henry; Koshy, Pramod; Chen, Hsin-Kai; Jiang, Yue; Sorrell, Charles Christopher

    2018-06-18

    Ce/Cr codoped TiO 2 nanoparticles were synthesized using sol-gel and Pechini methods with heat treatment at 400 °C for 4 h. A conventional sol-gel process produced well-crystallized anatase, while Pechini synthesis yielded less-ordered mixed-phase anatase + rutile; this suggests that the latter method enhances Ce solubility and increases chemical homogeneity but destabilizes the TiO 2 lattice. Greater structural disruption from the decomposition of the Pechini precursor formed more open agglomerated morphologies, while the lower levels of structural disruption from pyrolysis of the dried sol-gel precursor resulted in denser agglomerates of lower surface areas. Codoping and associated destabilization of the lattice reduced the binding energies in both powders. Cr 4+ formation in sol-gel powders and Cr 6+ formation in Pechini powders suggest that these valence changes derive from synergistic electron exchange from intervalence and/or multivalence charge transfer. Since Ce is too large to allow either substitutional or interstitial solid solubility, the concept of integrated solubility is introduced, in which the Ti site and an adjacent interstice are occupied by the large Ce ion. The photocatalytic performance data show that codoping was detrimental owing to the effects of reduced crystallinity from lattice destabilization and surface area. Two regimes of mechanistic behavior are seen, which are attributed to the unsaturated solid solutions at lower codopant levels and supersaturated solid solutions at higher levels. The present work demonstrates that the Pechini method offers a processing technique that is superior to sol-gel because the former facilitates solid solubility and consequent chemical homogeneity.

  12. Electrochemical sensor based on graphene and mesoporous TiO2 for the simultaneous determination of trace colourants in food.

    Science.gov (United States)

    Gan, Tian; Sun, Junyong; Meng, Wen; Song, Li; Zhang, Yuxia

    2013-12-15

    Currently, synthetic colourants draw much attention as food additives. This paper investigated the simultaneous electrocatalytic oxidation of sunset yellow and tartrazine, two yellow colourants commonly present in food together, with a novel voltammetric sensor based on graphene and mesoporous TiO2 modified carbon paste electrode. Due to the high accumulation effect and great catalytic capability of graphene and mesoporous TiO2, the developed sensor exhibited well-defined and separate square wave voltammetric peaks (i.e., 272 mV) for sunset yellow tartrazine. The peak currents of sunset yellow and tartrazine increased linearly with their concentration in the ranges of 0.02-2.05 μM and 0.02-1.18 μM, respectively. And the detection limit was 6.0 and 8.0 nM for sunset yellow and tartrazine, respectively. This new sensor was applied to determine sunset yellow and tartrazine in several food sample extracts. Results suggested that the proposed sensor was sensitive, rapid and reliable. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Microstructure and antibacterial property of in situ TiO(2) nanotube layers/titanium biocomposites.

    Science.gov (United States)

    Cui, C X; Gao, X; Qi, Y M; Liu, S J; Sun, J B

    2012-04-01

    The TiO(2) nanotube layer was in situ synthesized on the surface of pure titanium by the electrochemical anodic oxidation. The diameter of nano- TiO(2) nanotubes was about 70~100 nm. The surface morphology and phase compositions of TiO(2) nanotube layers were observed and analyzed using the scanning electron microscope (SEM). The important processing parameters, including anodizing voltage, reaction time, concentration of electrolyte, were optimized in more detail. The photocatalytic activity of the nano- TiO(2) nanotube layers prepared with optimal conditions was evaluated via the photodegradation of methylthionine in aqueous solution. The antibacterial property of TiO(2) nanotube layers prepared with optimal conditions was evaluated by inoculating Streptococcus mutans on the TiO(2) nanotube layers in vitro. The results showed that TiO(2) nanotube layers/Ti biocomposites had very good antibacterial activity to resist Streptococcus mutans. As a dental implant biomaterial, in situ TiO(2) nanotube layer/Ti biocomposite has better and wider application prospects. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. MoSe2 modified TiO2 nanotube arrays with superior photoelectrochemical performance

    Science.gov (United States)

    Zhang, Yaping; Zhu, Haifeng; Yu, Lianqing; He, Jiandong; Huang, Chengxing

    2018-04-01

    TiO2 nanotube arrays (TNTs) are first prepared by anodization Ti foils in ethylene glycol electrolyte. Then, MoSe2 deposites electrochemically on TNTs. The as-synthesized MoSe2/TiO2 composite has a much higher photocurrent density of 1.07 mA cm‑2 at 0 V than pure TNTs of 0.38 mA cm‑2, which suggests that the MoSe2/TiO2 composite film has optimum photoelectrocatalysis properties. The electron transport resistances of the MoSe2/TiO2 decreases to half of pure TiO2, at 295.6 ohm/cm2. Both photocurrent-time and Mott-Schottky plots indicate MoSe2 a p-type semiconductor characteristics. MoSe2/TiO2 composite can achieve a maximum 5 orders of magnitude enhancement in carrier density (4.650 × 1027 cm‑3) than that of pure TiO2 arrays. It can be attributed to p-n heterojunction formed between MoSe2 and TiO2, and the composite can be potentially applied in photoelectrochemical, photocatalysis fields.

  15. Electrochemically Obtained TiO2/CuxOy Nanotube Arrays Presenting a Photocatalytic Response in Processes of Pollutants Degradation and Bacteria Inactivation in Aqueous Phase

    Directory of Open Access Journals (Sweden)

    Magda Kozak

    2018-06-01

    Full Text Available TiO2/CuxOy nanotube (NT arrays were synthesized using the anodization method in the presence of ethylene glycol and different parameters applied. The presence, morphology, and chemical character of the obtained structures was characterized using a variety of methods—SEM (scanning electron microscopy, XPS (X-ray photoelectron spectroscopy, XRD (X-ray crystallography, PL (photoluminescence, and EDX (energy-dispersive X-ray spectroscopy. A p-n mixed oxide heterojunction of Ti-Cu was created with a proved response to the visible light range and the stable form that were in contact with Ti. TiO2/CuxOy NTs presented the appearance of both Cu2O (mainly and CuO components influencing the dimensions of the NTs (1.1–1.3 µm. Additionally, changes in voltage have been proven to affect the NTs’ length, which reached a value of 3.5 µm for Ti90Cu10_50V. Degradation of phenol in the aqueous phase was observed in 16% of Ti85Cu15_30V after 1 h of visible light irradiation (λ > 420 nm. Scavenger tests for phenol degradation process in presence of NT samples exposed the responsibility of superoxide radicals for degradation of organic compounds in Vis light region. Inactivation of bacteria strains Escherichia coli (E. coli, Bacillus subtilis (B. subtilis, and Clostridium sp. in presence of obtained TiO2/CuxOy NT photocatalysts, and Vis light has been studied showing a great improvement in inactivation efficiency with a response rate of 97% inactivation for E. coli and 98% for Clostridium sp. in 60 min. Evidently, TEM (transmission electron microscopy images confirmed the bacteria cells’ damage.

  16. Photocatalytic properties of P25-doped TiO2 composite film synthesized via sol-gel method on cement substrate.

    Science.gov (United States)

    Guo, Xiang; Rao, Lei; Wang, Peifang; Wang, Chao; Ao, Yanhui; Jiang, Tao; Wang, Wanzhong

    2018-04-01

    TiO 2 films have received increasing attention for the removal of organic pollutants via photocatalysis. To develop a simple and effective method for improving the photodegradation efficiency of pollutants in surface water, we herein examined the preparation of a P25-TiO 2 composite film on a cement substrate via a sol-gel method. In this case, Rhodamine B (RhB) was employed as the target organic pollutant. The self-generated TiO 2 film and the P25-TiO 2 composite film were characterized by X-ray diffraction (XRD), N 2 adsorption/desorption measurements, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and diffuse reflectance spectroscopy (DRS). The photodegradation efficiencies of the two films were studied by RhB removal in water under UV (ultraviolet) irradiation. Over 4day exposure, the P25-TiO 2 composite film exhibited higher photocatalytic performance than the self-generated TiO 2 film. The photodegradation rate indicated that the efficiency of the P25-TiO 2 composite film was enhanced by the addition of the rutile phase Degussa P25 powder. As such, cooperation between the anatase TiO 2 and rutile P25 nanoparticles was beneficial for separation of the photo-induced electrons and holes. In addition, the influence of P25 doping on the P25-TiO 2 composite films was evaluated. We found that up to a certain saturation point, increased doping enhanced the photodegradation ability of the composite film. Thus, we herein demonstrated that the doping of P25 powders is a simple but effective strategy to prepare a P25-TiO 2 composite film on a cement substrate, and the resulting film exhibits excellent removal efficiency in the degradation of organic pollutants. Copyright © 2017. Published by Elsevier B.V.

  17. Study of the electrochemical behavior at low temperatures of green anodes for Lithium ion batteries prepared with anatase TiO2 and water soluble sodium carboxymethyl cellulose binder

    International Nuclear Information System (INIS)

    Mancini, M.; Nobili, F.; Tossici, R.; Marassi, R.

    2012-01-01

    Highlights: ► Water soluble CMC and PVDF binders are used to prepare anatase TiO 2 electrodes. ► The electrochemical behavior of the different electrodes is studied between 20 and −30 °C. ► CMC/TiO 2 anodes show lower ICL, lower polarization and higher low-temperature capacity at high rates than PVDF/TiO 2 anodes. ► Electrochemical Impedance Spectroscopy results show better kinetics for CMC/TiO 2 electrodes. - Abstract: The electrochemical behavior at low temperatures of anatase TiO 2 electrodes for Lithium ion batteries have been evaluated by galvanostatic cycles in the temperature range 20 to −30 °C. Two different manufacturing processes have been used to prepare anatase anodes containing water soluble sodium carboxymethyl cellulose (CMC) or poly(vinilydene fluoride) (PVDF) as binder. The low temperature performances at different charge/discharge rates of TiO 2 /CMC and TiO 2 /PVDF electrodes are compared and discussed in terms of irreversible capacity loss (ICL) at the first cycle, capacity retention and reversible capacity. The kinetics of the electrodes containing CMC or PVDF is evaluated by Electrochemical Impedance Spectroscopy.

  18. Fabrication, characterization and photocatalytic properties of Ag nanoparticles modified TiO2 NTs

    International Nuclear Information System (INIS)

    Wang Qingyao; Yang Xiuchun; Liu Dan; Zhao Jianfu

    2012-01-01

    Graphical abstract: The TiO 2 NTs were first treated with bi-functional mercaptoacetic acid linkers (HOOC–R–S). The –OH group on the surface of TiO 2 NT provides a strong affinity with the carboxylate group in the linker molecules. The thiol functional group in the linker molecules facilitates the binding with Ag from AgNO 3 solution. After Ag + ions were reduced by NaBH 4 , Ag nanoparticles formed by nucleation and growth. Highlights: ► Ag nanoparticles with an average diameter of 9.2 nm were filled in the TiO 2 nanotubes by a successive ionic layer adsorption and reaction (SILAR) technique. ► Bi-functional mercaptoacetic acid linkers were used to bind TiO 2 nanotubes with Ag nanoparticles. ► Ag nanoparticles modification of TiO 2 NTs largely enhanced the photocatalytic degradation of methyl orange under ultraviolet light irradiation. - Abstract: Ordered anatase TiO 2 nanotubes (TiO 2 NTs) on Ti substrate were synthesized by electrochemical anodization and subsequently vapor-thermal treatment. Ag nanoparticles were decorated on TiO 2 NTs by successive ionic layer adsorption and reaction (SILAR) technique. Raman spectroscopy, X-ray absorption near edge spectroscopy (XANES), X-ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for the characterization of surface morphology, phase composition, and microstructure of the original TiO 2 NTs, the vapor-thermally treated TiO 2 NTs and the Ag nanoparticles decorated TiO 2 NTs. The results indicate that vapor-thermal treatment favors to the transformation of amorphous TiO 2 into anatase phase. Increasing the SILAR cycle times favors to increase the loaded amounts of Ag nanoparticles in TiO 2 NTs. Ag nanoparticles are uniformly distributed in the TiO 2 NTs, and the SILAR process does not damage the ordered tubular structure. A possible formation mechanism of Ag/TiO 2 NTs has also been proposed. The

  19. Room temperature alcohol sensing by oxygen vacancy controlled TiO2 nanotube array

    International Nuclear Information System (INIS)

    Hazra, A.; Dutta, K.; Bhowmik, B.; Bhattacharyya, P.; Chattopadhyay, P. P.

    2014-01-01

    Oxygen vacancy (OV) controlled TiO 2 nanotubes, having diameters of 50–70 nm and lengths of 200–250 nm, were synthesized by electrochemical anodization in the mixed electrolyte comprising NH 4 F and ethylene glycol with selective H 2 O content. The structural evolution of TiO 2 nanoforms has been studied by field emission scanning electron microscopy. Variation in the formation of OVs with the variation of the structure of TiO 2 nanoforms has been evaluated by photoluminescence and X-ray photoelectron spectroscopy. The sensor characteristics were correlated to the variation of the amount of induced OVs in the nanotubes. The efficient room temperature sensing achieved by the control of OVs of TiO 2 nanotube array has paved the way for developing fast responding alcohol sensor with corresponding response magnitude of 60.2%, 45.3%, and 36.5% towards methanol, ethanol, and 2-propanol, respectively.

  20. Amine functionalized TiO2-carbon nanotube composite: synthesis, characterization and application to glucose biosensing

    Science.gov (United States)

    Tasviri, Mahboubeh; Rafiee-Pour, Hossain-Ali; Ghourchian, Hedayatollah; Gholami, Mohammad Reza

    2011-12-01

    The synthesis of amine functionalized TiO2-coated multiwalled carbon nanotubes (NH2-TiO2-CNTs) using sol-gel method was investigated. The synthesized nanocomposite was characterized with XRD, FTIR spectroscopy, BET test and SEM imaging. The results demonstrated a unique nanostructure with no destruction of the CNTs' shape. In addition, the presence of amine groups on the composite surface was confirmed by FTIR. This nanocomposite was used for one-step immobilization of glucose oxidase (GOx) to sense glucose. The result of cyclic voltammetry showed a pair of well-defined and quasi-reversible peaks for direct electron transfer of GOx in the absence of glucose. Also, the result of electrochemical impedance spectroscopy indicated that GOx was successfully immobilized on the surface of NH2-TiO2-CNTs. Furthermore, good amperometric response showed that immobilized GOx on the NH2-TiO2-CNTs exhibits exceptional bioelectrocatalytic activity toward glucose oxidation.

  1. Enhanced photocatalytic, electrochemical and photoelectrochemical properties of TiO2 nanotubes arrays modified with Cu, AgCu and Bi nanoparticles obtained via radiolytic reduction

    International Nuclear Information System (INIS)

    Nischk, Michał; Mazierski, Paweł; Wei, Zhishun; Siuzdak, Katarzyna; Kouame, Natalie Amoin; Kowalska, Ewa; Remita, Hynd; Zaleska-Medynska, Adriana

    2016-01-01

    Highlights: • TiO 2 nanotubes were modified with Cu, AgCu, Bi nanoparticles via gamma radiolysis. • Excessive amount of deposited metal decreased photocatalytic activity. • AgCu-modified samples were more active than Cu-modified (with the same Cu content). • AgCu nanoparticles exist in a core (Ag) -shell (Cu) form. • Examined photocatalysts were resistant towards photocorrosion processes. - Abstract: TiO 2 nanotubes arrays (NTs), obtained via electrochemical anodization of Ti foil, were modified with monometallic (Cu, Bi) and bimetallic (AgCu) nanoparticles. Different amounts of metals’ precursors were deposited on the surface of NTs by the spin-coating technique, and the reduction of metals was performed via gamma radiolysis. Surface modification of titania was studied by EDS and XPS analysis. The results show that AgCu nanoparticles exist in a Ag core -Cu shell form. Photocatalytic activity was examined under UV irradiation and phenol was used as a model pollutant of water. Over 95% of phenol degradation was achieved after 60 min of irradiation for almost all examined samples, but only slight difference in degradation efficiency (about 3%) between modified and bare NTs was observed. However, the initial phenol degradation rate and TOC removal efficiency was significantly enhanced for the samples modified with 0.31 and 0.63 mol% of Bi as well as for all the samples modified with Cu and AgCu nanoparticles in comparison with bare titania nanotubes. The saturated photocurrent, under the influence of simulated solar light irradiation, for the most active Bi- and AgCu-modified samples, was over two times higher than for pristine NTs. All the examined materials were resistant towards photocorrosion processes that enables their application for long term processes induced by light.

  2. Electrochemical degradation of triazole fungicides in aqueous solution using TiO2-NTs/SnO2-Sb/PbO2 anode: Experimental and DFT studies

    International Nuclear Information System (INIS)

    Han, Weiqing; Zhong, Congqiang; Liang, Linyue; Sun, Yunlong; Guan, Ying; Wang, Lianjun; Sun, Xiuyun; Li, Jiansheng

    2014-01-01

    Triazole fungicides (TFs) are toxic and bio-refractory contaminants widely spread in environment. This study investigated electrochemical degradation of TFs in aqueous solution at TiO 2 -NTs/SnO 2 -Sb/PbO 2 anode with particular attention to the effect of molecular structure. Three TFs with triazole ring in one biologically treated water including tricyclazole (TC), 1H-1,2,4-triazole (Tz) and propiconazole (PPC) were selected as the target compounds. Results of bulk electrolysis showed that degradation of all TFs was fit to a pseudo first-order equation. The three compounds were degraded with the following sequence: PPC > TC> Tz in terms of their rates of oxidation. Quantum chemical calculation using the density function theory (DFT) method was combined with experimental results to describe the degradation sequence of TFs. Atom charge was calculated by DFT method and active sites of TFs were identified respectively. Analysis of intermediates by GC-MS and LC-(ESI)-MS/MS showed agreement with calculation results. In addition, the acute toxicity of TC and PPC treated solution significantly decreased after treatment by electrochemical oxidation

  3. Photocatalytic growth of Ag nanocrystals on hydrothermally synthesized multiphasic TiO2/reduced graphene oxide (rGO) nanocomposites and their SERS performance

    Science.gov (United States)

    Guo, Tian-Long; Li, Ji-Guang; Sun, Xudong; Sakka, Yoshio

    2017-11-01

    TiO2/reduced graphene oxide (rGO) nanocomposites were prepared via a facile one-step hydrothermal method using TiCl3 as the TiO2 precursor. Cetyltrimethyl ammonium bromide (CTAB) was introduced as a stabilizer for GO in solution. The effects of GO content, Ti3+ concentration and urea additive on phase constituent and morphology of the TiO2 crystallites in the nanocomposites were systematically investigated. UV-vis absorption ability of the as-made composites was further tested and discussed. Ag nanocrystals (NCs) were photocatalytically grown on the surfaces of biphasic (anatase + brookite) and triphasic (anatase + brookite + rutile) TiO2/rGO nanocomposites to evaluate their surface-enhanced Raman scattering (SERS) performances. Morphology evolution of the Ag NCs in response to different photocatalytic ability of the TiO2/rGO nanocomposite was also investigated in detail. The nanocomposite with triphasic TiO2 of proper phase constituents was confirmed to favor the growth of Ag particles of two distinctly different sizes and to produce SERS substrates of substantially better performance.

  4. Photo-assisted electrochemical oxidation of the urea onto TiO2-nanotubes modified by hematite

    Directory of Open Access Journals (Sweden)

    Waleed M. Omymen

    2017-12-01

    Full Text Available The electrochemical oxidation of the urea in near neutral pH is investigated on platinum electrode. It is shown that oxidation reaction is practically inhibited up to the potentials of ∼0.9 V. The same reaction is investigated onto electrochemically obtained titanium dioxide nanotubes modified by hematite using facile, low-cost successive ion layer adsorption and reaction (SILAR method. It is shown that such system possesses electrocatalytic activity at very low potentials, and activity can be further improved by the illumination of the electrode in the photo-assisted reaction. The possible application of the photoactive anode is considered in the application of urea based water electrolysis and urea based fuel cell. Keywords: Photoelectrochemical cell, Water electrolysis, Fuel cell, SILAR

  5. Development of solar-driven electrochemical and photocatalytic water treatment system using a boron-doped diamond electrode and TiO2 photocatalyst.

    Science.gov (United States)

    Ochiai, Tsuyoshi; Nakata, Kazuya; Murakami, Taketoshi; Fujishima, Akira; Yao, Yanyan; Tryk, Donald A; Kubota, Yoshinobu

    2010-02-01

    A high-performance, environmentally friendly water treatment system was developed. The system consists mainly of an electrochemical and a photocatalytic oxidation unit, with a boron-doped diamond (BDD) electrode and TiO(2) photocatalyst, respectively. All electric power for the mechanical systems and the electrolysis was able to be provided by photovoltaic cells. Thus, this system is totally driven by solar energy. The treatment ability of the electrolysis and photocatalysis units was investigated by phenol degradation kinetics. An observed rate constant of 5.1 x 10(-3)dm(3)cm(-2)h(-1) was calculated by pseudo-first-order kinetic analysis for the electrolysis, and a Langmuir-Hinshelwood rate constant of 5.6 microM(-1)min(-1) was calculated by kinetic analysis of the photocatalysis. According to previous reports, these values are sufficient for the mineralization of phenol. In a treatment test of river water samples, large amounts of chemical and biological contaminants were totally wet-incinerated by the system. This system could provide 12L/day of drinking water from the Tama River using only solar energy. Therefore, this system may be useful for supplying drinking water during a disaster. (c) 2009 Elsevier Ltd. All rights reserved.

  6. Addition of IrO2 to RuO2+TiO2 coated anodes and its effect on electrochemical performance of anodes in acid media

    Directory of Open Access Journals (Sweden)

    Farhad Moradi

    2014-04-01

    Full Text Available Ternary mixed metal oxide coatings with the nominal composition IrxRu(0.6−xTi0.4O2 (x=0, 0.1, 0.2, 0.3 on the titanium substrate were prepared by thermal decomposition of a chloride precursor mixture. Surface morphology and microstructure of the coatings were investigated by Scanning electron microscopy (SEM, Field emission scanning electron microscopy (FE-SEM and X-ray diffraction (XRD analysis. Systematic study of electrochemical properties of these coatings was performed by cyclic voltammetry (CV and polarization measurements. The corrosion behavior of the coatings was evaluated under accelerated conditions (j=2 A cm−2 in acidic electrolyte. The role of iridium oxide admixture in the change of electrocatalytic activity and stability of Ru0.6Ti0.4O2 coating was discussed. Small addition of IrO2 can improve the stability of the RuO2+TiO2 mixed oxide, while the electrocatalytic activity for oxygen evolution reaction (OER is decreased. The shift of redox potentials for Ru0.6Ti0.4O2 electrode that is slightly activated with IrO2 and improvement in the stability can be attributed to the synergetic effect of mixed oxide formation.

  7. 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.

  8. Electrochemical fabrication of TiO2 nanoparticles/[BMIM]BF4 ionic liquid hybrid film electrode and its application in determination of p-acetaminophen

    International Nuclear Information System (INIS)

    Wang, Bin; Li, Yuan; Qin, Xianjing; Zhan, Guoqing; Ma, Ming; Li, Chunya

    2012-01-01

    A water soluble ionic liquid, 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([BMIM]BF 4 ), was incorporated into TiO 2 nanoparticles to fabricate a hybrid film modified glassy carbon electrode (nano‐TiO 2 /[BMIM]BF 4 /GCE) through electrochemical deposition in a tetrabutyltitanate sol solution containing [BMIM]BF 4 . The obtained nano‐TiO 2 /[BMIM]BF 4 /GCEs were characterized scanning electronic microscopy (SEM) and X‐ray photoelectron spectroscopy (XPS). Electrochemical behaviors of p‐acetaminophen at the nano‐TiO 2 /[BMIM]BF 4 /GCEs were thoroughly investigated. Compared to the redox reaction of p‐acetaminophen using an unmodified electrode under the same conditions, a new reduction peak was observed clearly at 0.26 V with the modified electrode. In addition, the peak potential for the oxidation of p‐acetaminophen was found to shift negatively about 90 mV and the current response increased significantly. These changes indicate that the nano‐TiO 2 /[BMIM]BF 4 hybrid film can improve the redox reactions of p‐acetaminophen in aqueous medium. Under optimum conditions, a linear relationship was obtained for the p‐acetaminophen solutions with concentration in the range from 5.0 × 10 −8 to 5.0 × 10 −5 M. The estimated detection limit was 1.0 × 10 −8 M (S/N = 3). The newly developed method was applied for the determination of p-acetaminophen in urine samples. - Highlights: ► Nano-TiO 2 /[BMIM]BF 4 hybrid film electrode was fabricated with electrodeposition. ► Voltammetric behavior of p-acetaminophen at the obtained electrode was investigated. ► The hybrid film electrode shows good electrocatalytic response to p-acetaminophen. ► p-acetaminophen in urine samples was successfully determined.

  9. PHOTO-ELECTROCHEMICAL QUANTUM EFFICIENCY OF TiO2 THIN FILMS : EFFECT OF CRISTAL STRUCTURE, PLASMA HYDROGENATION AND SURFACE PHOTOETCHING

    Directory of Open Access Journals (Sweden)

    E TEYAR

    2007-12-01

    Full Text Available The use of semi-conducting materials in the photoelectrochemical detoxification of water became a very important research field. For this purpose, TiO2 nanostructures thin films with size of 18 nm to 45nm have been synthesized at low temperature. It is found by means of cyclic voltametry and coulometry measurements that the best photoelectrochemical quantum efficiency under UV monochromatic light with a wavelength of 365 nm and a solution of NaOH 0.1N is obtained in the case of thermal oxidation deposition method which can reach 28% compared to ultrasonic spray and dip coating methods of which the quantum is less than 20%. The crystal structure has an influence on the photo-degradation of methanol. The crystal structure which is recommended for this task is the anatase one, especially in the dipping case when the quantum increases after addition of methanol more than twice compared to the solution of NaOH without methanol. The photoelectrochemical quantum efficiency of these films is related to the number of dips and annealing under air at 550°C during one hour. The annealing has no effect on the quantum efficiency of the films, but decreases there photocatalytic activity as showed by the measure of the photocurrent related to methanol photodegradation. The annealing has no effect on the crystal structure of the material. The impedance spectroscopy of six dips deposited films with and without methanol shows that the annealing increases the doping and weakly decreases the film quantum efficiency. This implies, the importance of surface morphology which the rough is decreasing as showed by scanning electron microscopy. The effect of the precursor concentration in ethanol have been investigated by using films, synthesized at T=550°C. The quantum efficiency increases weakly according the precursor concentration. It tends towards a saturation at great concentrations of precursor. In Na OH with methanol added, it passes by a maximum at

  10. Quantum dot sensitized solar cell based on TiO2/CdS/Ag2S heterostructure

    Science.gov (United States)

    Pawar, Sachin A.; Patil, Dipali S.; Kim, Jin Hyeok; Patil, Pramod S.; Shin, Jae Cheol

    2017-04-01

    Quantum dot sensitized solar cell (QDSSC) is fabricated based on a stepwise band structure of TiO2/CdS/Ag2S to improve the photoconversion efficiency of TiO2/CdS system by incorporating a low band gap Ag2S QDs. Vertically aligned TiO2 nanorods assembly is prepared by a simple hydrothermal technique. The formation of CdS and Ag2S QDs over TiO2 nanorods assembly as a photoanode is carried out by successive ionic layer adsorption and reaction (SILAR) technique. The synthesized electrode materials are characterized by XRD, XPS, field emission scanning electron microscopy (FE-SEM), Optical, solar cell and electrochemical performances. The results designate that the QDs of CdS and Ag2S have efficiently covered exterior surfaces of TiO2 nanorods assembly. A cautious evaluation between TiO2/CdS and TiO2/CdS/Ag2S sensitized cells tells that CdS and Ag2S synergetically helps to enhance the light harvesting ability. Under AM 1.5G illumination, the photoanodes show an improved power conversion efficiency of 1.87%, in an aqueous polysulfide electrolyte with short-circuit photocurrent density of 7.03 mA cm-2 which is four fold higher than that of a TiO2/CdS system.

  11. Electrochemical impedance spectroscopy to study photo - induced effects on self-organized TiO2 nanotube arrays

    International Nuclear Information System (INIS)

    Pu, P.; Cachet, H.; Sutter, E.M.M.

    2010-01-01

    Two different morphologies of nano-structured titanium dioxide-a nanotubular layer and a compact layer - were obtained by anodization of titanium in fluoride-based baths, and the photo-induced effects of these layers were investigated by electrochemical impedance spectroscopy (EIS). The first layer showed long-lasting photo-induced modifications after UV illumination, whereas, in the case of the compact layer, no long-lasting UV-induced modifications were observed. Before light exposure, in the nanotubular layer, only the bottom of the tubes were electro-active and contributed to the conduction of the layer. Moreover an exponential distribution of surface states could be evidenced. After UV exposure, the surface states were filled by the photo-generated electrons, leading to activation of the walls of the tubes by inserted hydrogen, and to a hundred fold increase in the space charge layer capacitance. This capacitance increase was attributed to an increase in the active surface of the layer, but also to an increase in the charge carrier density.

  12. A facile method to synthesize nitrogen and fluorine co-doped TiO2 nanoparticles by pyrolysis of (NH4)2TiF6

    International Nuclear Information System (INIS)

    Chen Daimei; Jiang Zhongyi; Geng Jiaqing; Zhu Juhong; Yang Dong

    2009-01-01

    The nitrogen and fluorine co-doped TiO 2 (N-F-TiO 2 ) nanoparticles of anatase crystalline structure were prepared by a facile method of (NH 4 ) 2 TiF 6 pyrolysis, and characterized by thermogravimetry-differential thermal analysis (TG-DTA), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and ultraviolet visible (UV-Vis) spectroscopy etc. With the increase of calcination temperature, (NH 4 ) 2 TiF 6 decomposed into TiOF 2 and NH 4 TiOF 3 at first, and then formed anatase-type TiO 2 with thin sheet morphology. H 3 BO 3 as oxygen source can promote the formation of anatase TiO 2 , but decrease the F content in the N-F-TiO 2 materials due to the formation of volatile BF 3 during the precursor decomposition. The photocatalytic activity of the obtained N-F-TiO 2 samples was evaluated by the methylene blue degradation under visible light, and all the samples exhibited much higher photocatalytic activity than P25. Moreover, the merits and disadvantages of this proposed method to prepare doped TiO 2 are discussed.

  13. High-Quality Fe-doped TiO2 films with Superior Visible-Light Performance

    DEFF Research Database (Denmark)

    Su, Ren; Bechstein, Ralf; Kibsgaard, Jakob

    2012-01-01

    We report on high-quality polycrystalline Fe-doped TiO2 (Fe–TiO2) porous films synthesized via one-step electrochemical oxidation. We demonstrate that delicate properties such as the impurity concentration and the microstructure that strongly influence the performance of the material for photovol...

  14. Characterization and Comparison of Photocatalytic Activity Silver Ion doped on TiO2(TiO2/Ag+) and Silver Ion doped on Black TiO2(Black TiO2/Ag+)

    Science.gov (United States)

    Kim, Jin Yi; Sim, Ho Hyung; Song, Sinae; Noh, Yeoung Ah; Lee, Hong Woon; Taik Kim, Hee

    2018-03-01

    Titanium dioxide (TiO2) is one of the representative ceramic materials containing photocatalyst, optic and antibacterial activity. The hydroxyl radical in TiO2 applies to the intensive oxidizing agent, hence TiO2 is suitable to use photocatalytic materials. Black TiO2was prepared through reduction of amorphous TiO2 conducting under H2 which leads to color changes. Its black color is proven that absorbs 100% light across the whole-visible light, drawing enhancement of photocatalytic property. In this study, we aimed to compare the photocatalytic activity of silver ion doped on TiO2(TiO2/Ag+) and silver ion doped on black TiO2(black TiO2/Ag+) under visible light range. TiO2/Ag+ was fabricated following steps. 1) TiO2 was synthesized by a sol-gel method from Titanium tetraisopropoxide (TTIP). 2) Then AgNO3 was added during an aging process step for silver ion doping on the surface of TiO2. Moreover, Black TiO2/Ag+ was obtained same as TiO2/Ag+ except for calcination under H2. The samples were characterized X-ray diffraction (XRD), UV-visible reflectance (UV-vis DRS), and Methylene Blue degradation test. XRD analysis confirmed morphology of TiO2. The band gap of black TiO2/Ag+ was confirmed (2.6 eV) through UV-vis DRS, which was lower than TiO2/Ag+ (2.9 eV). The photocatalytic effect was conducted by methylene blue degradation test. It demonstrated that black TiO2/Ag+ had a photocatalytic effect under UV light also visible light.

  15. Defect-rich TiO2-δ nanocrystals confined in a mooncake-shaped porous carbon matrix as an advanced Na ion battery anode

    Science.gov (United States)

    He, Hanna; Zhang, Qi; Wang, Haiyan; Zhang, Hehe; Li, Jiadong; Peng, Zhiguang; Tang, Yougen; Shao, Minhua

    2017-06-01

    Inferior electronic conductivity and sluggish sodium ion diffusion are still two big challenges for TiO2 anode material for Na ion batteries (SIBs). Herein, we synthesize TiO2/C composites by the pyrolysis of MIL-125(Ti) precursor and successfully introduce defects to TiO2/C composite by a simple magnesium reduction. The as-prepared defect-rich TiO2-δ/C composite shows mooncake-shaped morphology consisting of TiO2-δ nanocrystals with an average particle size of 5 nm well dispersed in the carbon matrix. When used as a SIBs anode, the defect-rich TiO2-δ/C composite exhibits a high reversible capacity of 330.2 mAh g-1 at 50 mA g-1 at the voltage range of 0.001-3.0 V and long-term cycling stability with negligible decay after 5000 cycles. Compared with other four TiO2/C samples, the electrochemical performance of defect-rich TiO2-δ/C is highly improved, which may benefit from the enhanced electronic/ionic conductivities owing to the defect-rich features, high surface area rendering shortened electronic and ionic diffusion path, and the suppress of the TiO2 crystal aggregation during sodiation and desodiation process by the carbon matrix.

  16. Structural Modification of Sol-Gel Synthesized V2O5 and TiO2 Thin Films with/without Erbium Doping

    Directory of Open Access Journals (Sweden)

    Fatma Pınar Gökdemir

    2014-01-01

    Full Text Available Comparative work of with/without erbium- (Er- doped vanadium pentoxide (V2O5 and titanium dioxide (TiO2 thin films were carried out via sol-gel technique by dissolving erbium (III nitrate pentahydrate (Er(NO33·5H2O in vanadium (V oxoisopropoxide (OV[OCH(CH32]3 and titanium (IV isopropoxide (Ti[OCH(CH32]4. Effect of Er doping was traced by Fourier transform IR (FTIR, thermogravimetric/differential thermal (TG/DTA, and photoluminescence measurements. UV-Vis transmission/absorption measurement indicated a blue shift upon Er doping in V2O5 film due to the softening of V=O bond while appearance of typical absorption peaks in Er-doped TiO2 film. Granule size of the films increased (reduced upon Er substitution on host material compared to undoped V2O5 and TiO2 films, respectively.

  17. 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.

  18. Electrochemically synthesized nanocrystalline spinel thin film for high performance supercapacitor

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Vinay [Carbon Technology Unit, Engineering Materials Division, National Physical Laboratory, New-Delhi, 110012 (India); Art, Science and Technology Center for Cooperative Research, Kyushu University, Kasuga-shi, Fukuoka, 816-8580 (Japan); Japan Science and Technology Agency, Kawaguchi-shi, Saitama, 332-0012 (Japan); Gupta, Shubhra; Miura, Norio [Art, Science and Technology Center for Cooperative Research, Kyushu University, Kasuga-shi, Fukuoka, 816-8580 (Japan)

    2010-06-01

    Spinels are not known for their supercapacitive nature. Here, we have explored electrochemically synthesized nanostructured NiCo{sub 2}O{sub 4} spinel thin-film electrode for electrochemical supercapacitors. The nanostructured NiCo{sub 2}O{sub 4} spinel thin film exhibited a high specific capacitance value of 580 F g{sup -1} and an energy density of 32 Wh kg{sup -1} at the power density of 4 kW kg{sup -1}, accompanying with good cyclic stability. (author)

  19. Study of the highly ordered TiO2 nanotubes physical properties prepared with two-step anodization

    Science.gov (United States)

    Pishkar, Negin; Ghoranneviss, Mahmood; Ghorannevis, Zohreh; Akbari, Hossein

    2018-06-01

    Highly ordered hexagonal closely packed titanium dioxide nanotubes (TiO2 NTs) were successfully grown by a two-step anodization process. The TiO2 NTs were synthesized by electrochemical anodization of titanium foils in an ethylene glycol based electrolyte solution containing 0.3 wt% NH4F and 2 vol% deionized (DI) water at constant potential (50 V) for 1 h at room temperature. Physical properties of the TiO2 NTs, which were prepared via one and two-step anodization, were investigated. Atomic Force Microscopy (AFM) analysis revealed that anodization and subsequently peeled off the TiO2 NTs caused to the periodic pattern on the Ti surface. In order To study the nanotubes morphology, Field Emission Scanning Electron Microscopy (FESEM) was used, which was revealed that the two-step anodization resulted highly ordered hexagonal TiO2 NTs. Crystal structures of the TiO2 NTs were mainly anatase, determined by X-ray diffraction analysis. Optical studies were performed by Diffuse Reflection Spectra (DRS) and Photoluminescence (PL) analysis showed that the band gap of TiO2 NTs prepared via two-step anodization was lower than the band gap of samples prepared by one-step anodization process.

  20. Antibacterial effect of novel synthesized sulfated β-cyclodextrin crosslinked cotton fabric and its improved antibacterial activities with ZnO, TiO2 and Ag nanoparticles coating.

    Science.gov (United States)

    Selvam, S; Rajiv Gandhi, R; Suresh, J; Gowri, S; Ravikumar, S; Sundrarajan, M

    2012-09-15

    Sulfated β-cyclodextrin was synthesized from sulfonation of β-cyclodextrin and sulfated polymer was crosslinked with cotton fabric using ethylenediaminetetraacetic acid as crosslinker. ZnO, TiO(2) and Ag nanoparticles were prepared and characterized by XRD, UV, DLS, SEM and PSA. The prepared nanoparticles were coated on crosslinked cotton fabric. The crosslinking and nanoparticles coating effects of cotton fabrics were studied by FTIR and SEM analysis. The antibacterial test was done against gram positive Staphylococcus aureus and gram negative Escherichia coli bacterium. Copyright © 2012 Elsevier B.V. All rights reserved.

  1. Effect of growth time on the structure, morphology and optical properties of hydrothermally synthesized TiO2 nanorod thin films

    Science.gov (United States)

    Mohapatra, A. K.; Nayak, J.

    2018-05-01

    Titanium dioxide (TiO2) nanorod thin films were deposited on fluorine doped tin oxide coated glass substrates by a single step rapid hydrothermal process. The concentration of the precursor, the temperature of the reaction mixture were optimized in order to enhance the rate of deposition. Unlike the previously reported hydrothermal treatment for 24 - 48 h, the deposition of well aligned titanium dioxide nanorods was achieved in a short time such as 3 - 8 h. The crystal structure of the films were investigated by X-rays diffraction. The morphology of the nanorod films were studied with scanning electron microscopy. The optical properties were studied by photoluminescence spectroscopy.

  2. Chalcogenide Sensitized Carbon Based TiO2 Nanomaterial For Solar Driven Applications

    Science.gov (United States)

    Pathak, Pawan

    The demand for renewable energy is growing because fossils fuels are depleting at a rapid pace. Solar energy an abundant green energy resource. Utilizing this resource in a smart manner can resolve energy-crisis related issues. Sun light can be efficiently harvested using semiconductor based materials by utilizing photo-generated charges for numerous beneficial applications. The main goal of this thesis is to synthesize different nanostructures of TiO2, develop a novel method of coupling and synthesizing chalcogenide nanocrystals with TiO2 and to study the charge transportation effects of the various carbon allotropes in the chalcogenide nanocrystal sensitized TiO2 nanostructure. We have fabricated different nanostructures of TiO2 as solar energy harvesting materials. Effects of the different phases of TiO2 have also been studied. The anatase phase of TiO2 is more photoactive than the rutile phase of TiO2, and the higher dimension of the TiO2 can increase the surface area of the material which can produce higher photocurrent. Since TiO2 only absorbs in the UV range; to increase the absorbance TiO2 should be coupled to visible light absorbing materials. This dissertation presents a simple approach to synthesize and couple chalcogenide nanocrystals with TiO2 nanostructure to form a heterostructured composite. An atmospheric pressure based, single precursor, one-pot approach has been developed and tested to assemble chalcogenide nanocrystal on the TiO2 surface. Surface characterization using microscopy, X-ray diffraction, and elemental analysis indicates the formation of nanocrystals along the nanotube walls and inter-tubular spacing. Optical measurements indicate that the chalcogenide nanocrystals absorb in the visible region and demonstrate an increase in photocurrent in comparison to bare TiO2 nanostructure. The CdS synthesized TiO2 nanostructure produced the highest photocurrent as measured in the three electrode system. We have also assembled the PbS nanocrystal

  3. Molecular Engineering, Photophysical and Electrochemical Characterizations of Novel Ru(II) and BODIPY Sensitizers for Mesoporous TiO2 Solar Cells

    Science.gov (United States)

    Cheema, Hammad Arshad

    precludes coplanarity of the naphthalene moiety, thus decreasing the extracted photocurrent response from solar device. The findings were published in Dyes and Pigments (doi:10.1016/j.dyepig.2014.08.005). For HD-7 and HD-8, intriguing difference caused by structural isomerization based on anthracene and phenanthrene stilbazole type ancillary ligands, respectively in Ru (II) sensitizers was investigated using femtosecond transient absorption spectroscopy. It was found that the excited electrons in HD-7 are prone to ISC (intersystem crossing) much more than that in HD-8 and those triplet electrons are not being injected in TiO2 efficiently as discussed in Chapter 5. To achieve long term stability, we combined the strong electron donor characteristics of carbazole and the hydrophobic nature of long alkyl chains, C7 (HD-14 ), C18 (HD-15) and C2 (NCSU-10), tethered to N-carbazole. HD-15 showed strikingly good long term light soaking stability and maintained up to 98% of initial efficiency value compared to 92% for HD-14 and 78% for NCSU-10, as discussed in Chapter 6. Boron dipyromethene (BODIPY) dyes HB-1, HB-2 and HB-3 were synthesized and fully characterized for dye solar cells. It was found that having long alkyl chains tethered to the donor groups alone are not sufficient for achieving highly efficient photovoltaic response from BODIPY dyes (Chapter 7). Thus, replacement of fluorines from BODIPY core with long alkoxy chains has been suggested for future work.

  4. Electrochemical reduction induced self-doping of Ti3+ for efficient water splitting performance on TiO2 based photoelectrodes

    KAUST Repository

    Zhang, Zhonghai; Hedhili, Mohamed N.; Zhu, Haibo; Wang, Peng

    2013-01-01

    Hetero-element doping (e.g., N, F, C) of TiO2 is inevitably accompanied by significantly increased structural defects due to the dopants' nature being foreign impurities. Very recently, in situ self-doping with homo-species (e.g., Ti3+) has been

  5. Enhanced photoelectrochemical and photocatalytic behaviors of MFe2O4 (M = Ni, Co, Zn and Sr) modified TiO2 nanorod arrays

    Science.gov (United States)

    Gao, Xin; Liu, Xiangxuan; Zhu, Zuoming; Wang, Xuanjun; Xie, Zheng

    2016-07-01

    Modified TiO2 nanomaterials are considered to be promising in energy conversion and ferrites modification may be one of the most efficient modifications. In this research, various ferrites, incorporated with various cations (MFe2O4, M = Ni, Co, Zn, and Sr), are utilized to modify the well aligned TiO2 nanorod arrays (NRAs), which is synthesized by hydrothermal method. It is found that all MFe2O4/TiO2 NRAs show obvious red shift into the visible light region compared with the TiO2 NRAs. In particular, NiFe2O4 modification is demonstrated to be the best way to enhance the photoelectrochemical and photocatalytic activity of TiO2 NRAs. Furthermore, the separation and transfer of charge carriers after MFe2O4 modification are clarified by electrochemical impedance spectroscopy measurements. Finally, the underlying mechanism accounting for the enhanced photocatalytic activity of MFe2O4/TiO2 NRAs is proposed. Through comparison among different transition metals modified TiO2 with the same synthesis process and under the same evaluating condition, this work may provide new insight in designing modified TiO2 nanomaterials as visible light active photocatalysts.

  6. Improvement of epoxy resin properties by incorporation of TiO2 nanoparticles surface modified with gallic acid esters

    International Nuclear Information System (INIS)

    Radoman, Tijana S.; Džunuzović, Jasna V.; Jeremić, Katarina B.; Grgur, Branimir N.; Miličević, Dejan S.; Popović, Ivanka G.; Džunuzović, Enis S.

    2014-01-01

    Highlights: • Nanocomposites of epoxy resin and TiO 2 nanoparticles surface modified with gallates. • The T g of epoxy resin was increased by incorporation of surface modified TiO 2 . • WVTR of epoxy resin decreased in the presence of surface modified TiO 2 nanoparticles. • WVTR of nanocomposites was reduced with increasing gallates hydrophobic chain length. • Modified TiO 2 nanoparticles react as oxygen scavengers, inhibiting steel corrosion. - Abstract: Epoxy resin/titanium dioxide (epoxy/TiO 2 ) nanocomposites were obtained by incorporation of TiO 2 nanoparticles surface modified with gallic acid esters in epoxy resin. TiO 2 nanoparticles were obtained by acid catalyzed hydrolysis of titanium isopropoxide and their structural characterization was performed by X-ray diffraction and transmission electron microscopy. Three gallic acid esters, having different hydrophobic part, were used for surface modification of the synthesized TiO 2 nanoparticles: propyl, hexyl and lauryl gallate. The gallate chemisorption onto surface of TiO 2 nanoparticles was confirmed by Fourier transform infrared and ultraviolet–visible spectroscopy, while the amount of surface-bonded gallates was determined using thermogravimetric analysis. The influence of the surface modified TiO 2 nanoparticles, as well as the length of hydrophobic part of the gallate used for surface modification of TiO 2 nanoparticles, on glass transition temperature, barrier, dielectric and anticorrosive properties of epoxy resin was investigated by differential scanning calorimetry, water vapor transmission test, dielectric spectroscopy, electrochemical impedance spectroscopy and polarization measurements. Incorporation of surface modified TiO 2 nanoparticles in epoxy resin caused increase of glass transition temperature and decrease of the water vapor permeability of epoxy resin. The water vapor transmission rate of epoxy/TiO 2 nanocomposites was reduced with increasing hydrophobic part chain length of

  7. High Efficiency Dye-sensitized Solar Cells Constructed with Composites of TiO2 and the Hot-bubbling Synthesized Ultra-Small SnO2 Nanocrystals.

    Science.gov (United States)

    Mao, Xiaoli; Zhou, Ru; Zhang, Shouwei; Ding, Liping; Wan, Lei; Qin, Shengxian; Chen, Zhesheng; Xu, Jinzhang; Miao, Shiding

    2016-01-13

    An efficient photo-anode for the dye-sensitized solar cells (DSSCs) should have features of high loading of dye molecules, favorable band alignments and good efficiency in electron transport. Herein, the 3.4 nm-sized SnO2 nanocrystals (NCs) of high crystallinity, synthesized via the hot-bubbling method, were incorporated with the commercial TiO2 (P25) particles to fabricate the photo-anodes. The optimal percentage of the doped SnO2 NCs was found at ~7.5% (SnO2/TiO2, w/w), and the fabricated DSSC delivers a power conversion efficiency up to 6.7%, which is 1.52 times of the P25 based DSSCs. The ultra-small SnO2 NCs offer three benefits, (1) the incorporation of SnO2 NCs enlarges surface areas of the photo-anode films, and higher dye-loading amounts were achieved; (2) the high charge mobility provided by SnO2 was confirmed to accelerate the electron transport, and the photo-electron recombination was suppressed by the highly-crystallized NCs; (3) the conduction band minimum (CBM) of the SnO2 NCs was uplifted due to the quantum size effects, and this was found to alleviate the decrement in the open-circuit voltage. This work highlights great contributions of the SnO2 NCs to the improvement of the photovoltaic performances in the DSSCs.

  8. Enhanced electrochemical oxidation of synthetic dyeing wastewater using SnO2-Sb-doped TiO2-coated granular activated carbon electrodes with high hydroxyl radical yields

    International Nuclear Information System (INIS)

    Li, Xinyang; Wu, Yue; Zhu, Wei; Xue, Fangqing; Qian, Yi; Wang, Chengwen

    2016-01-01

    Highlights: • We study granular activated carbon (GAC) electrodes coated with catalysts. • GAC coated with ATOT demonstrates an impressive ·OH yield. • This electrode can be used in continuous-flow three-dimensional electrode reactors. • We use Rhodamine B as a model organic compound for removal. • The GAC/ATOT performs better than all other electrodes examined. - Abstract: In this study, granular activated carbon (GAC) coated with SnO 2 -Sb doped TiO 2 (GAC/ATOT) with a high hydroxyl radical (·OH) yield is prepared via the sol-gel method. This material is utilized as a granular electrode in a continuous-flow three-dimensional electrode reactor (CTDER) for the enhanced treatment of synthetic dyeing wastewater containing Rhodamine B (RhB). We then characterize the physical properties, electrochemical properties, and electrochemical oxidation performance of the granular electrode. The results show that using the GAC/ATOT electrode in a CTDER significantly enhances the chemical oxygen demand (COD) removal, decreases the energy consumption, and improves the current efficiency of the wastewater. This is primarily attributed to the higher catalytic activity of GAC/ATOT for ·OH production compared to that of other candidates, such as TiO 2 coated GAC (GAC/T), Sb doped SnO 2 coated GAC (GAC/ATO), and pure GAC. The mechanism of the enhanced electrochemical oxidation afforded by using GAC/ATOT indicates that the high ·OH yield in the reactor packed with GAC/ATOT electrodes contributes to the enhanced electrochemical oxidation performance with respect to organic compounds.

  9. Enhancement of Perovskite Solar Cells Efficiency using N-Doped TiO2 Nanorod Arrays as Electron Transfer Layer.

    Science.gov (United States)

    Zhang, Zhen-Long; Li, Jun-Feng; Wang, Xiao-Li; Qin, Jian-Qiang; Shi, Wen-Jia; Liu, Yue-Feng; Gao, Hui-Ping; Mao, Yan-Li

    2017-12-01

    In this paper, N-doped TiO 2 (N-TiO 2 ) nanorod arrays were synthesized with hydrothermal method, and perovskite solar cells were fabricated using them as electron transfer layer. The solar cell performance was optimized by changing the N doping contents. The power conversion efficiency of solar cells based on N-TiO 2 with the N doping content of 1% (N/Ti, atomic ratio) has been achieved 11.1%, which was 14.7% higher than that of solar cells based on un-doped TiO 2 . To get an insight into the improvement, some investigations were performed. The structure was examined with X-ray powder diffraction (XRD), and morphology was examined by scanning electron microscopy (SEM). Energy dispersive spectrometer (EDS) and Tauc plot spectra indicated the incorporation of N in TiO 2 nanorods. Absorption spectra showed higher absorption of visible light for N-TiO 2 than un-doped TiO 2 . The N doping reduced the energy band gap from 3.03 to 2.74 eV. The photoluminescence (PL) and time-resolved photoluminescence (TRPL) spectra displayed the faster electron transfer from perovskite layer to N-TiO 2 than to un-doped TiO 2 . Electrochemical impedance spectroscopy (EIS) showed the smaller resistance of device based on N-TiO 2 than that on un-doped TiO 2 .

  10. Flower-like hydrogenated TiO2(B) nanostructures as anode materials for high-performance lithium ion batteries

    Science.gov (United States)

    Zhang, Zhonghua; Zhou, Zhenfang; Nie, Sen; Wang, Honghu; Peng, Hongrui; Li, Guicun; Chen, Kezheng

    2014-12-01

    Flower-like hydrogenated TiO2(B) nanostructures have been synthesized via a facile solvothermal approach combined with hydrogenation treatment. The obtained TiO2(B) nanostructures show uniform and hierarchical flower-like morphology with a diameter of 124 ± 5 nm, which are further constructed by primary nanosheets with a thickness of 10 ± 1.2 nm. The Ti3+ species and/or oxygen vacancies are well introduced into the structures of TiO2(B) after hydrogen reduction, resulting in an enhancement in the electronic conductivity (up to 2.79 × 10-3 S cm-1) and the modified surface electrochemical activity. When evaluated for lithium storage capacity, the hydrogenated TiO2(B) nanostructures exhibit enhanced electrochemical energy storage performances compared to the pristine TiO2(B) nanostructures, including high capacity (292.3 mA h g-1 at 0.5C), excellent rate capability (179.6 mA h g-1 at 10C), and good cyclic stability (98.4% capacity retention after 200 cycles at 10C). The reasons for these improvements are explored in terms of the increased electronic conductivity and the facilitation of lithium ion transport arising from the introduction of oxygen vacancies and the unique flower-like morphologies.

  11. Structural and electrochemical studies of TiO2 complexes with (4,4'-((1E,1'E)-(2,5-bis(octyloxy)-1,4-phenylene)bis(ethene-2,1-diyl))bis-(E)-N-(2,5-bis(octyloxy)benzylidene)) imine derivative bases towards organic devices.

    Science.gov (United States)

    Rozycka, Anna; Iwan, Agnieszka; Bogdanowicz, Krzysztof Artur; Filapek, Michal; Górska, Natalia; Hreniak, Agnieszka; Marzec, Monika

    2018-06-12

    Three (4,4'-((1E,1'E)-(2,5-bis(octyloxy)-1,4-phenylene)bis(ethene-2,1-diyl))bis-(E)-N-(2,5-bis(octyloxy)benzylidene)) imine derivatives were synthesized via a condensation reaction with p-toluenesulfonic acid as a catalyst. The effects of the end groups and vinylene (-HC[double bond, length as m-dash]CH-) moieties on the structural, thermal, optical, electrochemical and photovoltaic properties of imines were investigated to check the influence of TiO2 on the imine properties. The thermal behavior of imines and their complexes with TiO2 was widely investigated using FT-IR, XRD, DSC and POM methods in order to determine the order type in the imine structure. All imines present the highest occupied molecular orbital (HOMO) levels of about -5.39 eV (SAI1 and SAI2) and -5.27 eV (SAI3) and the lowest unoccupied molecular orbital (LUMO) levels at about -3.17 eV. The difference of the end groups in the imines in each case did not affect redox properties. Generally, both oxidation and reduction are easier after TiO2 addition and it also changes the HOMO-LUMO levels of imines. Moreover, changes in the characteristic bands for imines in the region 1500-1700 cm-1 observed as a drastic decrease of intensity or even disappearance of bands in the imine : TiO2 mixture suggest the formation of a complex (C[double bond, length as m-dash]N)-TiO2. Organic devices with the configuration of ITO/TiO2/SAIx (or SAIx : TiO2)/Au were fabricated and investigated in the presence and absence of visible light irradiation with an intensity of 93 mW cm-2. In all imines and complexes with TiO2, the generation of the photocurrent indicates their use as photodiodes and the best result was observed for SAI3 : TiO2 complexes.

  12. Preparation of anatase TiO2 nanoparticles using low hydrothermal temperature for dye-sensitized solar cell

    Science.gov (United States)

    Sofyan, N.; Ridhova, A.; Yuwono, A. H.; Udhiarto, A.

    2018-03-01

    One device being developed as an alternative source of renewable energy by utilizing solar energy source is dye-sensitized solar cells (DSSC). This device works using simple photosynthetic-electrochemical principle in the molecular level. In this device, the inorganic oxide semiconductor of titanium dioxide (TiO2) has a great potential for the absorption of the photon energy from the solar energy source, especially in the form of TiO2 nanoparticle structure. This nanoparticle structure is expected to improve the performance of DSSC because the surface area to weight ratio of this nanostructures is very large. In this study, the synthesis of TiO2 nanoparticle from its precursors has been performed along with the fabrication of the DSSC device. Effort to improve the size of nanocrystalline anatase TiO2 was accomplished by low hydrothermal treatment at various temperatures whereas the crystallinity of the anatase phase in the structure was performed by calcination process. Characterization of the materials was performed using X-ray Diffraction (XRD) and scanning electron microscope (SEM), while the DSSC performance was examined through a high precision current versus voltage (I-V) curve analyzer. The results showed that pure anatase TiO2 nanoparticles could be obtained at low hydrothermal of 100, 125, and 150 °C followed by calcination at 450 °C. The best performance of photocurrent-voltage characteristic was given by TiO2 hydrothermally synthesized at 150 °C with power conversion efficiency (PCE) of 4.40 %, whereas the standard TiO2 nanoparticles has PCE only 4.02 %. This result is very promising in terms low temperature and thus low cost of anatase TiO2 semiconductor preparation for DSSC application.

  13. Plasma-induced synthesis of Pt nanoparticles supported on TiO2 nanotubes for enhanced methanol electro-oxidation

    Science.gov (United States)

    Su, Nan; Hu, Xiulan; Zhang, Jianbo; Huang, Huihong; Cheng, Jiexu; Yu, Jinchen; Ge, Chao

    2017-03-01

    A Pt/C/TiO2 nanotube composite catalyst was successfully prepared for enhanced methanol electro-oxidation. Pt nanoparticles with a particle size of 2 nm were synthesized by plasma sputtering in water, and anatase TiO2 nanotubes with an inner diameter of approximately 100 nm were prepared by a simple two-step anodization method and annealing process. Field-emission scanning electron microscopy images indicated that the different morphologies of TiO2 synthesized on the surface of Ti foils were dependent on the different anodization parameters. The electrochemical performance of Pt/C/TiO2 catalysts for methanol oxidation showed that TiO2 nanotubes were more suitable for use as Pt nanoparticle support materials than irregular TiO2 short nanorods due to their tubular morphology and better electronic conductivity. X-ray photoelectron spectroscopy characterization showed that the binding energies of the Pt 4f of the Pt/C/TiO2 nanotubes exhibited a slightly positive shift caused by the relatively strong interaction between Pt and the TiO2 nanotubes, which could mitigate the poisoning of the Pt catalyst by COads, and further enhance the electrocatalytic performance. Thus, the as-obtained Pt/C/TiO2 nanotubes composites may become a promising catalyst for methanol electro-oxidation.

  14. Electrochemically synthesized stretchable polypyrrole/fabric electrodes for supercapacitor

    International Nuclear Information System (INIS)

    Yue, Binbin; Wang, Caiyun; Ding, Xin; Wallace, Gordon G.

    2013-01-01

    Wearable electronics offer the combined advantages of both electronics and fabrics. Being an indispensable part of these electronics, lightweight, stretchable and wearable power sources are strongly demanded. Here we describe a daily-used cotton fabric coated with polypyrrole as electrode for stretchable supercapacitors. Polypyrrole was synthesized on the Au coated fabric via an electrochemical polymerization process with p-toluenesulfonic acid (p-TS) as dopant from acetonitrile solution. This material was characterized with FESEM, tensile stress, and studied as a supercapacitor electrode in 1.0 M NaCl. This conductive textile electrode can sustain up to 140% strain without electric failure. It delivers a high specific capacitance of 254.9 F g −1 at a scan rate of 10 mV s −1 , and keeps almost unchanged at an applied strain (i.e. 30% and 50%) but with an improved cycling stability

  15. Structural and Electrochemical Study of Vanadium-Doped TiO2 Ramsdellite with Superior Lithium Storage Properties for Lithium-Ion Batteries.

    Science.gov (United States)

    Pérez-Flores, Juan Carlos; Hoelzel, Markus; García-Alvarado, Flaviano; Kuhn, Alois

    2016-04-04

    Titanium-oxide-based materials are considered attractive and safe alternatives to carbonaceous anodes in Li-ion batteries. In particular, the ramsdellite form TiO2 (R) is known for its superior lithium-storage ability as the bulk material when compared with other titanates. In this work, we prepared V-doped lithium titanate ramsdellites with the formula Li0.5 Ti1-x Vx O2 (0≤x≤0.5) by a conventional solid-state reaction. The lithium-free Ti1-x Vx O2 compounds, in which the ramsdellite framework remains virtually unaltered, are easily obtained by a simple aqueous oxidation/ion-extraction process. Neutron powder diffraction is used to locate the Li channel site in Li0.5 Ti1-x Vx O2 compounds and to follow the lithium extraction by difference-Fourier maps. Previously delithiated Ti1-x Vx O2 ramsdellites are able to insert up to 0.8 Li(+) per transition-metal atom. The initial gravimetric capacities of 270 mAh g(-1) with good cycle stability under constant current discharge conditions are among the highest reported for bulk TiO2 -related intercalation compounds for the threshold of one e(-) per formula unit. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Scalable Synthesis of Triple-Core-Shell Nanostructures of TiO2 @MnO2 @C for High Performance Supercapacitors Using Structure-Guided Combustion Waves.

    Science.gov (United States)

    Shin, Dongjoon; Shin, Jungho; Yeo, Taehan; Hwang, Hayoung; Park, Seonghyun; Choi, Wonjoon

    2018-03-01

    Core-shell nanostructures of metal oxides and carbon-based materials have emerged as outstanding electrode materials for supercapacitors and batteries. However, their synthesis requires complex procedures that incur high costs and long processing times. Herein, a new route is proposed for synthesizing triple-core-shell nanoparticles of TiO 2 @MnO 2 @C using structure-guided combustion waves (SGCWs), which originate from incomplete combustion inside chemical-fuel-wrapped nanostructures, and their application in supercapacitor electrodes. SGCWs transform TiO 2 to TiO 2 @C and TiO 2 @MnO 2 to TiO 2 @MnO 2 @C via the incompletely combusted carbonaceous fuels under an open-air atmosphere, in seconds. The synthesized carbon layers act as templates for MnO 2 shells in TiO 2 @C and organic shells of TiO 2 @MnO 2 @C. The TiO 2 @MnO 2 @C-based electrodes exhibit a greater specific capacitance (488 F g -1 at 5 mV s -1 ) and capacitance retention (97.4% after 10 000 cycles at 1.0 V s -1 ), while the absence of MnO 2 and carbon shells reveals a severe degradation in the specific capacitance and capacitance retention. Because the core-TiO 2 nanoparticles and carbon shell prevent the deformation of the inner and outer sides of the MnO 2 shell, the nanostructures of the TiO 2 @MnO 2 @C are preserved despite the long-term cycling, giving the superior performance. This SGCW-driven fabrication enables the scalable synthesis of multiple-core-shell structures applicable to diverse electrochemical applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Anodic Materials for Lithium-ion Batteries: TiO2-rGO Composites for High Power Applications

    International Nuclear Information System (INIS)

    Minella, M.; Versaci, D.; Casino, S.; Di Lupo, F.; Minero, C.; Battiato, A.; Penazzi, N.; Bodoardo, S.

    2017-01-01

    Titanium dioxide/reduced graphene oxide (TiO 2 -rGO) composites were synthesized at different loadings of carbonaceous phase, characterized and used as anode materials in Lithium-ion cells, focusing not only on the high rate capability but also on the simplicity and low cost of the electrode production. It was therefore chosen to use commercial TiO 2 , GO was synthesized from graphite, adsorbed onto TiO 2 and reduced to rGO following a chemical, a photocatalytic and an in situ photocatalytic procedure. The synthesized materials were in-depth characterized with a multi-technique approach and the electrochemical performances were correlated i) to an effective reduction of the GO oxidized moieties and ii) to the maintenance of the 2D geometry of the final graphenic structure observed. TiO 2 -rGO obtained with the first two procedures showed good cycle stability, high capacity and impressive rate capability particularly at 10% GO loading. The photocatalytic reduction applied in situ on preassembled electrodes showed similarly good results reaching the goal of a further simplification of the anode production.

  18. Corrosion protection of AISI 1018 steel using Co-doped TiO_2/polypyrrole nanocomposites in 3.5% NaCl solution

    International Nuclear Information System (INIS)

    Ladan, Magaji; Basirun, Wan Jeffrey; Kazi, Salim Newaz; Rahman, Fariza Abdul

    2017-01-01

    A polypyrrole nanocomposites (PPy NTCs) have been effectively synthesized in the presence of TiO_2 and Co-doped TiO_2 nanoparticles (NPs) by an in situ chemical oxidative polymerization. Field Emission Scanning Electron Microscopy and Transmission Electron Microscopy revealed a tube shape structure of the PPy. The TEM results confirmed that the nanocomposite size of Co-doped TiO_2/PPy NTCs was smaller than TiO_2/PPy NTCs thereby increasing the interaction between the PPy nanotube and the AISI steel surface. The corrosion performance of the coatings was evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements in 3.5% NaCl solution. The EIS results show that the log |Z| of AISI 1018 coated with Co-doped TiO_2/PPy NTCs and TiO_2/PPy NTCs reached about 8.2 and 6.0 respectively after 30 days of exposure in 3.5% NaCl solution. This is likely due to the increased surface area of the PPy synthesized in the presence of Co-doped TiO_2 NPs. The EIS results are confirmed by the potentiodynamic polarization and open circuit potential values of the Co-doped TiO_2/PPy which indicated little changes between 1 and 30 days of exposure which confirms the protection ability of this coating. . It is evident that the presence of Co-doped TiO_2 NPs can enhance the resistance against corrosion at the steel/electrolyte interface. - Highlights: • Polymerization of pyrrole monomer in the presence of Co-doped TiO_2 decreases the size of the polypyrrole nanotube (PPy NT). • The corrosion protection increases with the increase in PPy NT dispersion. • The corrosion resistance of steel coated with Co-doped TiO_2/PPy NTCs is considerably higher. • TiO_2/PPy with Co doping reduces the charge transfer across the electrolyte/AISI 1018 steel interface.

  19. Hydrothermal synthesis of BiVO4/TiO2 composites and their application for degradation of gaseous benzene under visible light irradiation

    Science.gov (United States)

    Hu, Yin; Chen, Wei; Fu, Jianping; Ba, Mingwei; Sun, Fuqian; Zhang, Peng; Zou, Jiyong

    2018-04-01

    Benzene is currently recognized as one of the most toxic contaminants. Our previously published study revealed that BiVO4/TiO2 is an excellent photocatalyst toward the degradation of benzene. Herein, BiVO4/TiO2 has been synthesized via a sol-gel method and a facile hydrothermal route by adjusting the precursor hydrolysis rate with the use of different acids (CH3COOH, HNO3 and H2SO4). The influence of these acids on the physicochemical characteristics and photocatalytic performance is discussed in detail. X-ray diffraction and N2 sorption analyses confirm that acid has an important effect on the crystalline composition and BET specific surface area. BiVO4/TiO2 synthesized in CH3COOH has better photocatalytic activity for the degradation of gaseous benzene than that in HNO3 and H2SO4 under visible light irradiation. Results of XPS measurement demonstrate that the hydroxyl group in BiVO4/TiO2-CH3COOH is more abundant than that in BiVO4/TiO2-HNO3 and BiVO4/TiO2-H2SO4. The photocurrent signal is investigated by electrochemical measurement, which indicates that more effective separation of photogenerated carriers occurs in the BiVO4/TiO2/CH3COOH system. It is hoped that our work can offer valuable information on the design of TiO2 composites with enhanced properties.

  20. Synthesis of calcium-phosphorous doped TiO2 nanotubes by anodization and reverse polarization: A promising strategy for an efficient biofunctional implant surface

    International Nuclear Information System (INIS)

    Alves, Sofia A.; Patel, Sweetu B.; Sukotjo, Cortino; Mathew, Mathew T.; Filho, Paulo N.; Celis, Jean-Pierre

    2017-01-01

    Highlights: • A new surface modification methodology for bio-functionalization of TiO2 NTs is addressed • Bone-like structured TiO2 nanotubular surfaces containing Ca and P were synthesized. • Ca/P-doped TiO2 NTs enhanced adhesion and proliferation of osteoblastic-like cells. • The bio-functionalization granted improved bio-electrochemical stability to TiO2 NTs. - Abstract: The modification of surface features such as nano-morphology/topography and chemistry have been employed in the attempt to design titanium oxide surfaces able to overcome the current dental implants failures. The main goal of this study is the synthesis of bone-like structured titanium dioxide (TiO 2 ) nanotubes enriched with Calcium (Ca) and Phosphorous (P) able to enhance osteoblastic cell functions and, simultaneously, display an improved corrosion behavior. To achieve the main goal, TiO 2 nanotubes were synthetized and doped with Ca and P by means of a novel methodology which relied, firstly, on the synthesis of TiO 2 nanotubes by anodization of titanium in an organic electrolyte followed by reverse polarization and/or anodization, in an aqueous electrolyte. Results show that hydrophilic bone-like structured TiO 2 nanotubes were successfully synthesized presenting a highly ordered nano-morphology characterized by non-uniform diameters. The chemical analysis of such nanotubes confirmed the presence of CaCO 3 , Ca 3 (PO 4 ) 2 , CaHPO 4 and CaO compounds. The nanotube surfaces submitted to reverse polarization, presented an improved cell adhesion and proliferation compared to smooth titanium. Furthermore, these surfaces displayed a significantly lower passive current in artificial saliva, and so, potential to minimize their bio-degradation through corrosion processes. This study addresses a very simple and promising multidisciplinary approach bringing new insights for the development of novel methodologies to improve the outcome of osseointegrated implants.

  1. Electrochemically synthesized Si nano wire arrays and thermoelectric nano structures

    International Nuclear Information System (INIS)

    Khuan, N.I.; Ying, K.K.; Nur Ubaidah Saidin; Foo, C.T.

    2012-01-01

    Thermoelectric nano structures hold great promise for capturing and directly converting into electricity some vast amount of low-grade waste heats now being lost to the environment (for example from nuclear power plant, fossil fuel burning, automotive and household appliances). In this study, large-area vertically-aligned silicon nano wire (SiNW) arrays were synthesized in an aqueous solution containing AgNO 3 and HF on p-type Si (100) substrate by self-selective electroless etching process. The etching conditions were systematically varied in order to achieve different stages of nano wire formation. Diameters of the SiNWs obtained varied from approximately 50 to 200 nm and their lengths ranged from several to a few tens of μm. Te/ Bi 2 Te 3 -Si thermoelectric core-shell nano structures were subsequently obtained via galvanic displacement of SiNWs in acidic HF electrolytes containing HTeO 2 + and Bi 3+ / HTeO 2 + ions. The reactions were basically a nano-electrochemical process due to the difference in redox potentials between the materials. the surface-modified SiNWs of core-shell structures had roughened surface morphologies and therefore, higher surface-t-bulk ratios compared to unmodified SiNWs. They have potential applications in sensors, photovoltaic and thermoelectric nano devices. Growth study on the SiNWs and core-shell nano structures produced is presented using various microscopy, diffraction and probe-based techniques for microstructural, morphological and chemical characterizations. (Author)

  2. Electrochemical study of RuO2 and/or TiO2 pyrolytic films on titanium in the range of voltage corresponding to water stability

    International Nuclear Information System (INIS)

    Barral, Gerard

    1988-01-01

    This research thesis can be considered as a preliminary part of the investigation of electrocatalytic properties of ruthenium and titanium dioxides. It proposes a presentation of electrochemical properties of interfaces between these oxides and the aqueous electrolyte in a voltage range corresponding to thermodynamic stabilities of water and dioxides. After a bibliographical study of methods of preparation of these materials and on the influence of the preparation mode on their physical characteristics and transient electrochemical behaviours, the author reports a detailed study of the hydrogen atom electro-sorption reaction. He discusses the variation of the main electrostatic characteristics of the space charge layer of various semiconducting phases with respect to the initial electric potential between the ends of this layer. He reports the experimental study of electrodes with porous ruthenium and / or titanium dioxides formed by pyrolysis or co-pyrolysis of chlorides of these metals [fr

  3. Oriented epitaxial TiO2 nanowires for water splitting

    Science.gov (United States)

    Hou, Wenting; Cortez, Pablo; Wuhrer, Richard; Macartney, Sam; Bozhilov, Krassimir N.; Liu, Rong; Sheppard, Leigh R.; Kisailus, David

    2017-06-01

    Highly oriented epitaxial rutile titanium dioxide (TiO2) nanowire arrays have been hydrothermally grown on polycrystalline TiO2 templates with their orientation dependent on the underlying TiO2 grain. Both the diameter and areal density of the nanowires were tuned by controlling the precursor concentration, and the template surface energy and roughness. Nanowire tip sharpness was influenced by precursor solubility and diffusivity. A new secondary ion mass spectrometer technique has been developed to install additional nucleation sites in single crystal TiO2 templates and the effect on nanowire growth was probed. Using the acquired TiO2 nanowire synthesis knowhow, an assortment of nanowire arrays were installed upon the surface of undoped TiO2 photo-electrodes and assessed for their photo-electrochemical water splitting performance. The key result obtained was that the presence of short and dispersed nanowire arrays significantly improved the photocurrent when the illumination intensity was increased from 100 to 200 mW cm-2. This is attributed to the alignment of the homoepitaxially grown nanowires to the [001] direction, which provides the fastest charge transport in TiO2 and an improved pathway for photo-holes to find water molecules and undertake oxidation. This result lays a foundation for achieving efficient water splitting under conditions of concentrated solar illumination.

  4. Study on preparation of SnO2-TiO2/Nano-graphite composite anode and electro-catalytic degradation of ceftriaxone sodium.

    Science.gov (United States)

    Guo, Xiaolei; Wan, Jiafeng; Yu, Xiujuan; Lin, Yuhui

    2016-12-01

    In order to improve the electro-catalytic activity and catalytic reaction rate of graphite-like material, Tin dioxide-Titanium dioxide/Nano-graphite (SnO 2 -TiO 2 /Nano-G) composite was synthesized by a sol-gel method and SnO 2 -TiO 2 /Nano-G electrode was prepared in hot-press approach. The composite was characterized by X-ray photoelectron spectroscopy, fourier transform infrared, Raman, N 2 adsorption-desorption, scanning electrons microscopy, transmission electron microscopy and X-ray diffraction. The electrochemical performance of the SnO 2 -TiO 2 /Nano-G anode electrode was investigated via cyclic voltammetry and electrochemical impedance spectroscopy. The electro-catalytic performance was evaluated by the degradation of ceftriaxone sodium and the yield of ·OH radicals in the reaction system. The results demonstrated that TiO 2 , SnO 2 and Nano-G were composited successfully, and TiO 2 and SnO 2 particles dispersed on the surface and interlamination of the Nano-G uniformly. The specific surface area of SnO 2 modified anode was higher than that of TiO 2 /Nano-G anode and the degradation rate of ceftriaxone sodium within 120 min on SnO 2 -TiO 2 /Nano-G electrode was 98.7% at applied bias of 2.0 V. The highly efficient electro-chemical property of SnO 2 -TiO 2 /Nano-G electrode was attributed to the admirable conductive property of the Nano-G and SnO 2 -TiO 2 /Nano-G electrode. Moreover, the contribution of reactive species ·OH was detected, indicating the considerable electro-catalytic activity of SnO 2 -TiO 2 /Nano-G electrode. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Solvothermal syntheses of Bi and Zn co-doped TiO_2 with enhanced electron-hole separation and efficient photodegradation of gaseous toluene under visible-light

    International Nuclear Information System (INIS)

    Li, Juan-Juan; Cai, Song-Cai; Xu, Zhen; Chen, Xi; Chen, Jin; Jia, Hong-Peng; Chen, Jing

    2017-01-01

    Highlights: • Bi-Zn co-doped TiO_2 catalysts were prepared by solvothermal route. • The incorporation of Bi doping into the TiO_2 generates intermediate energy levels. • Bi and Zn doping showed the enhanced absorption in visible-light region. • Zn dopant acts as a mediator of interfacial charge transfer. • TiBi_1_._9_%Zn_1_%O_2 exhibited high photocatalytic degradation for toluene. - Abstract: This study investigated the effects of Bi doped and Bi-Zn co-doped TiO_2 on photodegradation of gaseous toluene. The doped TiO_2 with various concentration of metal was prepared using the solvothermal route and characterized by SEM, XRD, Raman, BET, DRS, XPS, PL and EPR. Their photocatalytic activities under visible-light irradiation were drastically influenced by the dopant content. The results showed that moderate metal doping levels were obviously beneficial for the toluene degradation, while high doping levels suppressed the photocatalytic activity. The photocatalytic degradation of toluene over TiBi_1_._9_%O_2 and TiBi_1_._9_%Zn_1_%O_2 can reach to 51% and 93%, respectively, which are much higher than 25% of TiO_2. Bi doping into TiO_2 lattice generates new intermediate energy level of Bi below the CB edge of TiO_2. The electron excitation from the VB to Bi orbitals results in the decreased band gap, extended absorption of visible-light and thus enhances its photocatalytic efficiency. Zn doping not only further enhances the absorption in this visible-light region, but also Zn dopant exists as the form of ZnO crystallites located on the interfaces of TiO_2 agglomerates and acts as a mediator of interfacial charge transfer to suppress the electron-hole recombination. These synergistic effects are responsible for the enhanced photocatalytic performance.

  6. Photoelectrocatalytic properties of Ag nanoparticles loaded TiO2 nanotube arrays prepared by pulse current deposition

    International Nuclear Information System (INIS)

    Xie Kunpeng; Sun Lan; Wang Chenglin; Lai Yuekun; Wang Mengye; Chen Hongbo; Lin Changjian

    2010-01-01

    A pulse current deposition technique was adopted to construct highly dispersed Ag nanoparticles on TiO 2 nanotube arrays which were prepared by the electrochemical anodization. The morphology, crystallinity, elemental composition, and UV-vis absorption of Ag/TiO 2 nanotube arrays were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and diffuse reflectance spectra (DRS). In particular, the photoelectrochemical properties and photoelectrocatalytic activity under UV light irradiation and the photocatalytic activity under visible light irradiation for newly synthesized Ag/TiO 2 nanotube arrays were investigated. The maximum incident photon to charge carrier efficiency (IPCE) value of Ag/TiO 2 nanotube arrays was 51%, much higher than that of pure TiO 2 nanotube arrays. Ag/TiO 2 nanotube arrays exhibited higher photocatalytic activities than the pure TiO 2 nanotube arrays under both UV and visible light irradiation. The photoelectrocatalytic activity of Ag/TiO 2 nanotube arrays under UV light irradiation was 1.6-fold enhancement compared with pure TiO 2 nanotube arrays. This approach can be used in synthesizing various metal-loaded nanotube arrays materials.

  7. Few layer graphene wrapped mixed phase TiO2 nanofiber as a potential electrode material for high performance supercapacitor applications

    Science.gov (United States)

    Thirugnanam, Lavanya; Sundara, Ramaprabhu

    2018-06-01

    A combination of favorable composition and optimized anatase/rutile mixed-phase TiO2 (MPTNF)/Hydrogen exfoliated graphene (HEG) composite nanofibers (MPTNF/HEG) and anatase/rutile mixed-phase TiO2/reduced graphene oxide (rGO) composite nanofibers (MPTNF/rGO) have been reported to enhance the electrochemical properties for supercapacitor applications. These composite nanofibers have been synthesized by an efficient route of electrospinning together with the help of easy chemical methods. Both the composites exhibit good charge storage capability with enhanced pseudocapacitance and electric double-layer capacitance (EDLC) as confirmed by cyclic voltammetry studies. MPTNF/HEG composite showed maximum specific capacitance of 210.5 F/g at the current density of 1 A/g, which was mainly due to its availability of the more active sites for ions adsorption on a few layers of graphene wrapped TiO2 nanofiber surface. The synergistic effect of anatase/rutile mixed phase with one dimensional nanostructure and the electronic interaction between TiO2 and few layer graphene provided the subsequent improvement of ion adsorption capacity. Also exhibit excellent electrochemical performance to improve the capacitive properties of TiO2 electrode materials which is required for the development of flexible electrodes in energy storage devices and open up new opportunities for high performance supercapacitors.

  8. Superficial and electrochemical study of stainless steel 304l with an inhibitory protective coating (TiO2 and ZrO2)

    International Nuclear Information System (INIS)

    Davila N, M. L.; Contreras R, A.; Arganis J, C. R.

    2014-10-01

    The degradation mechanisms in the boiling water reactors (BWR) have been an alert focus for owners, especially the cracking by stress corrosion cracking (SCC), therefore different techniques have been studied to inhibit this problem inside which is the water injection of hydrogen feeding (HWC, Hydrogen Water Chemistry), together with the noble metals injection (NMCA, Nobel Metal Chemical Addition) and the ceramic materials injection that form an inhibitory protective coating (Ipc). In this work the Ipc was simulated, for which were carried out hydro-thermals deposits starting from suspensions of 1000 ppm of zirconium oxide in its crystalline phase baddeleyite and titanium oxides in its anatase and rutile phases, on test tubes of stainless steel 304l previously rusty under simulated conditions of pressure and temperature of a BWR (288 C and 8 MPa). The superficial characterization was realized by scanning electron microscopy, energy-dispersive of X-ray and X-ray diffraction. The capacity to mitigate the corrosion was studied with the electrochemical technique of Tafel polarization (288 C and 8 MPa). The steel presents the formation of two oxide coatings formed by magnetite and hematite. The baddeleyite presents a deposit more thick and homogeneous it also presents the most negative electrochemical potential of corrosion, what indicates that it has the bigger capacity to mitigate the SCC. (Author)

  9. Fabrication and Characteristics of Macroporous TiO2 Photocatalyst

    Directory of Open Access Journals (Sweden)

    Guiyun Yi

    2014-01-01

    Full Text Available Macroporous TiO2 photocatalyst was synthesized by a facile nanocasting method using polystyrene (PS spherical particles as the hard template. The synthesized photocatalyst was characterized by transmission electron microscope (TEM, scanning electron microscopy (SEM, thermogravimetry-differential thermogravimetry (TG-DTG, X-ray diffraction (XRD, and N2-sorption. TEM, SEM, and XRD characterizations confirmed that the macroporous TiO2 photocatalyst is composed of anatase phase. The high specific surface area of 87.85 m2/g can be achieved according to the N2-sorption analysis. Rhodamine B (RhB was chosen as probe molecule to evaluate the photocatalytic activity of the TiO2 catalysts. Compared with the TiO2 materials synthesized in the absence of PS spherical template, the macroporous TiO2 photocatalyst sintered at 500°C exhibits much higher activity on the degradation of RhB under the UV irradiation, which can be assigned to the well-structured macroporosity. The macroporous TiO2 material presents great potential in the fields of environmental remediation and energy conversion and storage.

  10. Photoelectrochemical oxidation of ibuprofen via Cu_2O-doped TiO_2 nanotube arrays

    International Nuclear Information System (INIS)

    Sun, Qiannan; Peng, Yen-Ping; Chen, Hanlin; Chang, Ken-Lin; Qiu, Yang-Neng; Lai, Shiau-Wu

    2016-01-01

    Highlights: • A p–n junction material was synthesized to enhance photocatalytic ability. • Cu_2O-doped TiO_2 nanotube arrays works as a photoanode in a PEC system. • Recombination of photo-generated holes and electrons were greatly reduced. • Synergetic effect was quantified in PEC degradation. • Recombination of photogenerated holes and electrons was greatly enhanced. - Abstract: A p–n junction based Cu_2O-doped TiO_2 nanotube arrays (Cu_2O-TNAs) were synthesized and used as a working anode in a photoelectrochemical (PEC) system. The results revealed that the Cu_2O-TNAs were dominated by the anatase phase and responded significantly to visible light. XPS analyses indicated that with an amount of 24.79% Cu doping into the structure, the band gap of Cu_2O-TNAs was greatly reduced. SEM images revealed that the supported TiO_2 nanotubes had diameters of approximately 80 nm and lengths of about 2.63 μm. Upon doping with Cu_2O, the TiO_2 nanotubes maintained their structural integrity, exhibiting no significant morphological change, favoring PEC applications. Under illumination, the photocurrent from Cu_2O/TNAs was 2.4 times larger than that from TNAs, implying that doping with Cu_2O significantly improved electron mobility by reducing the rate of recombination of electron-hole pairs. The EIS and Bode plot revealed that the estimated electron lifetimes, τ_e_l, of TNAs and Cu_2O/TNAs were 6.91 and 26.26 ms, respectively. The efficiencies of degradation of Ibuprofen by photoelectrochemical, photocatalytic (PC), electrochemical (EC) and photolytic (P) methods were measured.

  11. Dye-Sensitized Solar Cells with Anatase TiO2 Nanorods Prepared by Hydrothermal Method

    Directory of Open Access Journals (Sweden)

    Ming-Jer Jeng

    2013-01-01

    Full Text Available The hydrothermal method provides an effective reaction environment for the synthesis of nanocrystalline materials with high purity and well-controlled crystallinity. In this work, we started with various sizes of commercial TiO2 powders and used the hydrothermal method to prepare TiO2 thin films. We found that the synthesized TiO2 nanorods were thin and long when smaller TiO2 particles were used, while larger TiO2 particles produced thicker and shorter nanorods. We also found that TiO2 films prepared by TiO2 nanorods exhibited larger surface roughness than those prepared by the commercial TiO2 particles. It was found that a pure anatase phase of TiO2 nanorods can be obtained from the hydrothermal method. The dye-sensitized solar cells fabricated with TiO2 nanorods exhibited a higher solar efficiency than those fabricated with commercial TiO2 nanoparticles directly. Further, triple-layer structures of TiO2 thin films with different particle sizes were investigated to improve the solar efficiency.

  12. Interaction of NO during cathodic polarization in alkaline conditions at the interface of Pt-nanostructures supported on C and TiO2-C

    International Nuclear Information System (INIS)

    Estudillo-Wong, L.A.; Arce-Estrada, E.M.; Manzo-Robledo, A.

    2014-01-01

    The electroreduction of nitric oxide (NO) in alkaline media was carried out on Pt nanoparticles (5 wt.% Pt), which were synthesized by the carbonyl route. The as-prepared materials were supported on Carbon Black (XC-72R, C) and TiO 2 -C composite (10 wt.% TiO 2 ) and deposited on glassy carbon (GC) electrode. X-ray Diffraction (XRD), CO-stripping and hydrogen adsorption-desorption (H upd ) analysis were employed to characterize the structure and electrochemical properties. According to XRD patterns, the particle size increases from 3.95 to 8.98 nm due to the interaction of Pt with TiO 2 in the carbon matrix. This modification promotes a better performance during CO-oxidation and proton adsorption-desorption. As a consequence, the performance toward NO-reduction was more important in TiO 2 -C composite, linked with the electrochemical active-surface area and chemical surface area relationship (ECSA/CSA). It was found that the mechanism for the reduction of nitric oxide toward nitrogen is a bi-functional process with coupled chemical and electrochemical interfacial-reactions with NH 2 specie as intermediate, as demonstrated by the induced reduction reaction of NO 2 − and NO 2 − + NO, and UV-vis spectrometry

  13. Synthesis, structure and photocatalytic activity of nano TiO2 and ...

    Indian Academy of Sciences (India)

    salicylic acid over combustion-synthesized nano TiO2 under UV and solar exposure has been carried out. Under identical conditions of UV exposure, the initial degra- dation rate of phenol with combustion-synthesized TiO2 is two times higher than the initial degradation rate of phenol with Degussa P25, the commercial ...

  14. Exchange of TiO2 nanoparticles between streams and streambeds.

    Science.gov (United States)

    Boncagni, Natalia Ticiana; Otaegui, Justo Manuel; Warner, Evelyn; Curran, Trisha; Ren, Jianhong; de Cortalezzi, Maria Marta Fidalgo

    2009-10-15

    The expanding use of manufactured nanoparticles has increased the potential for their release into the natural environment. Particularly, TiO2 nanoparticles pose significant exposure risk to humans and other living species due to their extensive use in a wide range of fields. To better understand the environmental and health risks associated with the release of TiO2 nanoparticles, knowledge on their fate and transport is needed. This study evaluates the transport of two different TiO2 nanoparticles: one commercially available (P25 TiO2 and the other synthesized at a lab scale (synthesized TiO2). Laboratory flume, column, and batch experiments were conducted to investigate the processes dominating the transport of TiO2 nanoparticles between streams and streambeds and to characterize the properties of these nanoparticles under different physicochemical conditions. Results show that the synthesized TiO2 was more stable compared to the P25 TiO2, which underwent significant aggregation under the same experimental conditions. As a result, P25 TiO2 deposited at a faster rate than the synthesized TiO2 in the streambed. Both types of TiO2 nanoparticles deposited in the streambed were easily released when the stream velocity was increased. The aggregation and deposition of P25 TiO2 were highly dependent on pH. A process-based colloid exchange model was applied to interpret the observed transport behavior of the TiO2 nanoparticles.

  15. Photocatalytic decouloration of malachite green dye by application of TiO2 nanotubes

    International Nuclear Information System (INIS)

    Prado, Alexandre G.S.; Costa, Leonardo L.

    2009-01-01

    The nanotubes of titania were synthesized in a hydrothermal system and characterized by scanning electronic microscopy (SEM), FT-IR, FT-Raman, and surface charge density by surface area analyzer. These nanomaterials were applied to photocatalyse malachite green dye degradation. Photodegradation capacity of TiO 2 nanotubes was compared to TiO 2 anatase photoactivity. Malachite dye was completely degraded in 75 and 105 min of reaction photocatalysed by TiO 2 nanotubes and TiO 2 anatase, respectively. Catalysts displayed high photodegradation activity at pH 4. TiO 2 nanotubes were easily recycled whereas the reuse of TiO 2 anatase was not effective. Nanotubes maintained 80% of their activity after 10 catalytic cycles and TiO 2 anatase presented only 8% of its activity after 10 cycles.

  16. Synthesis of Nd3+doped TiO2 nanoparticles and Its Optical Behaviour

    Directory of Open Access Journals (Sweden)

    Ezhil Arasi S.

    2017-04-01

    Full Text Available Pure and Rare earth ion doped TiO2 nanoparticles were synthesized by Sol-gel method. The synthesized TiO2 nanoparticles were characterized by X-ray diffraction, Raman spectroscopy, UV–Vis spectroscopy and photoluminescence emission spectra. From the UV-visible measurement, the absorption edge of Nd3+-TiO2 was shifted to a higher wavelength side with decreasing band gap. Photoluminescence emission studies reveal the energy transfer mechanism of Nd3+ doped TiO2 nanoparticles explain.

  17. Application of nitrogen-doped TiO2 nano-tubes in dye-sensitized solar cells

    DEFF Research Database (Denmark)

    Tran, Vy Anh; Thinh Troung, Trieu; Pham Phan, Thu Anh

    2017-01-01

    Our research aimed to improve the overall energy conversion efficiency of DSCs by applying nitrogen-doped TiO2 nano-tubes (N-TNT) for the preparation of DSCs photo-anodes. The none-doped TiO2 nano-tubes (TNTs) were synthesized by alkaline hydrothermal treatment of Degussa P25 TiO2 particles in 10...

  18. Rapid charge-discharge property of Li4Ti5O12-TiO2 nanosheet and nanotube composites as anode material for power lithium-ion batteries.

    Science.gov (United States)

    Yi, Ting-Feng; Fang, Zi-Kui; Xie, Ying; Zhu, Yan-Rong; Yang, Shuang-Yuan

    2014-11-26

    Well-defined Li4Ti5O12-TiO2 nanosheet and nanotube composites have been synthesized by a solvothermal process. The combination of in situ generated rutile-TiO2 in Li4Ti5O12 nanosheets or nanotubes is favorable for reducing the electrode polarization, and Li4Ti5O12-TiO2 nanocomposites show faster lithium insertion/extraction kinetics than that of pristine Li4Ti5O12 during cycling. Li4Ti5O12-TiO2 electrodes also display lower charge-transfer resistance and higher lithium diffusion coefficients than pristine Li4Ti5O12. Therefore, Li4Ti5O12-TiO2 electrodes display lower charge-transfer resistance and higher lithium diffusion coefficients. This reveals that the in situ TiO2 modification improves the electronic conductivity and electrochemical activity of the electrode in the local environment, resulting in its relatively higher capacity at high charge-discharge rate. Li4Ti5O12-TiO2 nanocomposite with a Li/Ti ratio of 3.8:5 exhibits the lowest charge-transfer resistance and the highest lithium diffusion coefficient among all samples, and it shows a much improved rate capability and specific capacity in comparison with pristine Li4Ti5O12 when charging and discharging at a 10 C rate. The improved high-rate capability, cycling stability, and fast charge-discharge performance of Li4Ti5O12-TiO2 nanocomposites can be ascribed to the improvement of electrochemical reversibility, lithium ion diffusion, and conductivity by in situ TiO2 modification.

  19. Sol-gel synthesis of TiO2 nanoparticles and photocatalytic degradation of methyl orange in aqueous TiO2 suspensions

    International Nuclear Information System (INIS)

    Yang Huaming; Zhang Ke; Shi Rongrong; Li Xianwei; Dong Xiaodan; Yu Yongmei

    2006-01-01

    Anatase TiO 2 nanoparticles of about 16 nm in crystal size have been successfully synthesized via a sol-gel method. Thermal treatment of the precursor at 500-600 deg. C results in the formation of different TiO 2 phase compositions. The samples were characterized by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Effects of the pH value of the solution, H 2 O 2 addition, TiO 2 phase composition and recycled TiO 2 on the photocatalytic degradation of methyl orange (MeO) in TiO 2 suspensions under ultraviolet (UV) illumination were primarily investigated. The results indicate that a low pH value, proper amount of H 2 O 2 and pure anatase TiO 2 will facilitate the photocatalytic oxidation of the MeO solution. The photodegradation degree decreases with increasing the pH value of the solution and varies with different amounts of H 2 O 2 . Pure anatase TiO 2 shows better photocatalytic activity for MeO decolorization than biphase TiO 2 . The photocatalytic mechanism of the as-synthesized TiO 2 nanoparticles was discussed

  20. Resistive Switching Characteristics in Electrochemically Synthesized ZnO Films

    Directory of Open Access Journals (Sweden)

    Shuhan Jing

    2015-04-01

    Full Text Available The semiconductor industry has long been seeking a new kind of non-volatile memory technology with high-density, high-speed, and low-power consumption. This study demonstrated the electrochemical synthesis of ZnO films without adding any soft or hard templates. The effect of deposition temperatures on crystal structure, surface morphology and resistive switching characteristics were investigated. Our findings reveal that the crystallinity, surface morphology and resistive switching characteristics of ZnO thin films can be well tuned by controlling deposition temperature. A conducting filament based model is proposed to explain the switching mechanism in ZnO thin films.

  1. Amorphous TiO2 Shells: A Vital Elastic Buffering Layer on Silicon Nanoparticles for High-Performance and Safe Lithium Storage.

    Science.gov (United States)

    Yang, Jianping; Wang, Yunxiao; Li, Wei; Wang, Lianjun; Fan, Yuchi; Jiang, Wan; Luo, Wei; Wang, Yang; Kong, Biao; Selomulya, Cordelia; Liu, Hua Kun; Dou, Shi Xue; Zhao, Dongyuan

    2017-12-01

    Smart surface coatings of silicon (Si) nanoparticles are shown to be good examples for dramatically improving the cyclability of lithium-ion batteries. Most coating materials, however, face significant challenges, including a low initial Coulombic efficiency, tedious processing, and safety assessment. In this study, a facile sol-gel strategy is demonstrated to synthesize commercial Si nanoparticles encapsulated by amorphous titanium oxide (TiO 2 ), with core-shell structures, which show greatly superior electrochemical performance and high-safety lithium storage. The amorphous TiO 2 shell (≈3 nm) shows elastic behavior during lithium discharging and charging processes, maintaining high structural integrity. Interestingly, it is found that the amorphous TiO 2 shells offer superior buffering properties compared to crystalline TiO 2 layers for unprecedented cycling stability. Moreover, accelerating rate calorimetry testing reveals that the TiO 2 -encapsulated Si nanoparticles are safer than conventional carbon-coated Si-based anodes. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. XRD analysis of undoped and Fe doped TiO2 nanoparticles by Williamson Hall method

    International Nuclear Information System (INIS)

    Bharti, Bandna; Barman, P. B.; Kumar, Rajesh

    2015-01-01

    Undoped and Fe doped titanium dioxide (TiO 2 ) nanoparticles were synthesized by sol-gel method at room temperature. The synthesized samples were annealed at 500°C. For structural analysis, the prepared samples were characterized by X-ray diffraction (XRD). The crystallite size of TiO 2 and Fe doped TiO 2 nanoparticles were calculated by Scherer’s formula, and was found to be 15 nm and 11 nm, respectively. Reduction in crystallite size of TiO 2 with Fe doping was observed. The anatase phase of Fe-doped TiO 2 nanoparticles was also confirmed by X-ray diffraction. By using Williamson-Hall method, lattice strain and crystallite size were also calculated. Williamson–Hall plot indicates the presence of compressive strain for TiO 2 and tensile strain for Fe-TiO 2 nanoparticles annealed at 500°C

  3. High pressure synthesis of amorphous TiO2 nanotubes

    Directory of Open Access Journals (Sweden)

    Quanjun Li

    2015-09-01

    Full Text Available Amorphous TiO2 nanotubes with diameters of 8-10 nm and length of several nanometers were synthesized by high pressure treatment of anatase TiO2 nanotubes. The structural phase transitions of anatase TiO2 nanotubes were investigated by using in-situ high-pressure synchrotron X-ray diffraction (XRD method. The starting anatase structure is stable up to ∼20GPa, and transforms into a high-density amorphous (HDA form at higher pressure. Pressure-modified high- to low-density transition was observed in the amorphous form upon decompression. The pressure-induced amorphization and polyamorphism are in good agreement with the previous results in ultrafine TiO2 nanoparticles and nanoribbons. The relationship between the LDA form and α-PbO2 phase was revealed by high-resolution transmission electron microscopy (HRTEM study. In addition, the bulk modulus (B0 = 158 GPa of the anatase TiO2 nanotubes is smaller than those of the corresponding bulks and nanoparticles (180-240 GPa. We suggest that the unique open-ended nanotube morphology and nanosize play important roles in the high pressure phase transition of TiO2 nanotubes.

  4. Nanoscale Optimization and Statistical Modeling of Photoelectrochemical Water Splitting Efficiency of N-Doped TiO2 Nanotubes

    KAUST Repository

    Isimjan, Tayirjan T.; Trifkovic, Milana; Abdullahi, Inusa; Rohani, Sohrab M F; Ray, Ajay

    2014-01-01

    Highly ordered nitrogen-doped titanium dioxide (N-doped TiO2) nanotube array films with enhanced photo-electrochemical water splitting efficiency (PCE) for hydrogen generation were fabricated by electrochemical anodization, followed by annealing

  5. A thick hierarchical rutile TiO2 nanomaterial with multilayered structure

    International Nuclear Information System (INIS)

    Zhu, Shengli; Xie, Guoqiang; Yang, Xianjin; Cui, Zhenduo

    2013-01-01

    Highlights: ► We synthesized a new rutile TiO 2 nanomaterial with a hierarchical nanostructure. ► The nano architecture structure consist of nanorods and nanoflower arrays. ► The rutile TiO 2 nanomaterial is thick in size (several 10 μm). ► The TiO 2 nanomaterials present a multilayer structure. - Abstract: In the present paper, we synthesized a new type of rutile TiO 2 nanomaterial with a hierarchical nanostructure using a novel method, which combined dealloying process with chemical synthesis. The structure characters were examined using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The rutile TiO 2 nanomaterial is thick in size (several 10 μm). The hierarchical structure of the rutile TiO 2 nanomaterial consists of large quantities nanorods and nanoflower arrays. The nanoflowers consist of serveral nanopetals with diameter of 100–200 nm. The cross section of TiO 2 nanomaterials presents a multilayer structure with the layer thickness of about 3–5 μm. The rutile TiO 2 nanomaterial has high specific surface area. The formation mechanism of the rutile TiO 2 nanomaterial was discussed according to the experimental results. The rutile TiO 2 nanomaterial has potential applications in catalysis, photocatalysis and solar cells

  6. TiO2 Microflowers Assembled by 6-nm Single-Crystal Stranded Wires with Improved Photoelectrochemical Performances

    International Nuclear Information System (INIS)

    Liu, Chunlei; Zhou, Wei; Yu, Li; Zhang, Gong; Qu, Jiuhui; Liu, Huijuan

    2017-01-01

    Highlights: •The 6-nm single-crystal stranded wires of TiO 2 exhibited a photocurrent of 0.33 mA cm −2 compared to that of the P25/TF (0.06 mA cm −2 ), which greatly facilited the electron transfer rate. •A photoelectrochemical (PEC) system combining degradation of bisphenol A and H 2 production was constructed based on the TiO 2 -SWs/TF. •This PEC system exhibited a 94% bisphenol A degradation efficiency within 60 min at 1.2 V and H 2 production simultaneously. •A power consumption of only 0.02 kWh m −3 was consumed by the TiO 2 -SWs/TF in PEC system. •Two pathways for PEC degradation of bisphenol A were proposed based on the intermediates identified by UPLC-Q-TOF-MS. -- Abstract: As the diffusion length of charge carriers in TiO 2 is around 10 nm, it would be an efficient way to increase the photocatalytic properties by controlling the size within 10 nm. Herein, TiO 2 microflowers assembled by 6-nm single-crystal stranded wires grown on Ti foam (TiO 2 -SWs/TF) were synthesized which facilated electron transfer rate with a photocurrent of 0.33 mA cm −2 compared to that of the P25/TF (0.06 mA cm −2 ). A photoelectrochemical (PEC) system combining degradation of bisphenol A and H 2 production was constructed based on the as-obtained TiO 2 -SWs/TF as photoanode and Pt wire as cathode. This PEC system exhibited excellent ability for simultaneous bisphenol A degradation and H 2 production, giving a 94% bisphenol A degradation efficiency within 60 min at 1.2 vs (Ag/AgCl) V with power consumption of only 0.02 kWh m −3 . The excellent PEC degradation of bisphenol A by the TiO 2 -SWs/TF could mainly be ascribed to the fast electron transfer via the 6-nm ultrathin wires and synergetic effect of photocatalysis and electrochemical process. Two pathways for PEC degradation of bisphenol A were proposed based on the intermediates identified by Ultra Performance liquid chromatography-quadruple-time of flight-mass spectrometry (UPLC-Q-TOF-MS).

  7. Non-aqueous hybrid supercapacitors fabricated with mesoporous TiO2 microspheres and activated carbon electrodes with superior performance

    Science.gov (United States)

    Cai, Yong; Zhao, Bote; Wang, Jie; Shao, Zongping

    2014-05-01

    Mesoporous TiO2 microspheres, synthesized by a facile template-free solvothermal method and subsequent heat treatment, are exploited as the electrode for hybrid supercapacitors. The effects of the calcination temperature on the phase composition, particulate microstructure and morphology are characterized by XRD, Raman, FE-SEM and N2 adsorption/desorption measurements. Hybrid supercapacitors utilizing the as-prepared TiO2 mesoporous microspheres as the negative electrode and activated carbon (AC) as the positive electrode in a non-aqueous electrolyte are fabricated. The electrochemical performance of these hybrid supercapacitors is studied by galvanostatic charge-discharge and cyclic voltammetry (CV). The hybrid supercapacitor built from TiO2 microspheres calcined at 400 °C shows the best performance, delivering an energy density of 79.3 Wh kg-1 at a power density of 178.1 W kg-1. Even at a power density of 9.45 kW kg-1, an energy density of 31.5 Wh kg-1 is reached. These values are much higher than the AC-AC symmetric supercapacitor. In addition, the hybrid supercapacitor exhibits excellent cycling performance, retaining 98% of the initial energy density after 1000 cycles. Such outstanding electrochemical performance of the hybrid supercapacitor is attributed to the matched reaction kinetics between the two electrodes with different energy storage mechanisms.

  8. Mesoporous TiO2 nanosheets anchored on graphene for ultra long life Na-ion batteries

    Science.gov (United States)

    Zhang, Ruifang; Wang, Yuankun; Zhou, Han; Lang, Jinxin; Xu, Jingjing; Xiang, Yang; Ding, Shujiang

    2018-06-01

    Sodium-ion batteries, which have a similar electrochemical reaction mechanism to lithium-ion batteries, have been considered as one of the most potential lithium-ion battery alternatives due to the rich reserves of sodium. However, it is very hard to find appropriate electrode materials imputing the large radius of sodium-ion. TiO2 is particularly interesting as anodes for sodium-ion batteries due to their reasonable operation voltage, cost, and nontoxicity. To obtain a better electrochemical property, mesoporous TiO2 nanosheets (NSs)/reduced graphene oxide (rGO) composites have been synthesized via a scalable hydrothermal-solvothermal method with a subsequent calcination process. Benefitting from unique structure design, TiO2 NSs@rGO exhibits a superior cycle stability (90 mAh g‑1 after 10 000 cycles at a high current rate of 20 C) and satisfactory rate performance (97.3 mAh g‑1 at 25 C). To our knowledge, such ultra long cycle life has not previously been reported.

  9. Room temperature one-step synthesis of microarrays of N-doped flower-like anatase TiO2 composed of well-defined multilayer nanoflakes by Ti anodization

    Science.gov (United States)

    Wang, Chenglin; Wang, Mengye; Xie, Kunpeng; Wu, Qi; Sun, Lan; Lin, Zhiqun; Lin, Changjian

    2011-07-01

    Microarrays of N-doped flower-like TiO2 composed of well-defined multilayer nanoflakes were synthesized at room temperature by electrochemical anodization of Ti in NH4F aqueous solution. The TiO2 flowers were of good anatase crystallinity. The effects of anodizing time, applied voltage and NH4F concentration on the flower-like morphology were systematically examined. It was found that the morphologies of the anodized Ti were related to the anodizing time and NH4F concentration. The size and density of the TiO2 flowers could be tuned by changing the applied voltage. The obtained N-doped flower-like TiO2 microarrays exhibited intense absorption in wavelengths ranging from 320 to 800 nm. Under both UV and visible light irradiation, the photocatalytic activity of the N-doped flower-like TiO2 microarrays in the oxidation of methyl orange showed a significant increase compared with that of commercial P25 TiO2 film.

  10. Synthesis of titanate, TiO2 (B), and anatase TiO2 nanofibers from natural rutile sand

    International Nuclear Information System (INIS)

    Pavasupree, Sorapong; Suzuki, Yoshikazu; Yoshikawa, Susumu; Kawahata, Ryoji

    2005-01-01

    Titanate nanofibers were synthesized by hydrothermal method (150 deg. C for 72 h) using natural rutile sand as the starting materials. TiO 2 (B) and anatase TiO 2 (high crystallinity) nanofibers with the diameters of 20-100 nm and the lengths of 10-100 μm were obtained by calcined titanate nanofibers for 4 h at 400 and 700 deg. C (in air), respectively. The samples characterized by XRD, SEM, TEM, SAED, HRTEM, and BET surface area. This synthesis method provides a simple route to fabricate one-dimensional nanostructured TiO 2 from low cost material. -- Graphical abstract: Titanate nanofibers (b) were synthesized by hydrothermal method (150 deg. C for 72 h) using natural rutile sand (a) as the starting materials. TiO 2 (B) (c) and anatase TiO 2 (d) nanofibers with the diameters of 20-50 nm and the lengths of 10-100 μm were obtained by calcined titanate nanofibers for 4 h at 400 deg. C and 700 deg. C (in air), respectively

  11. Eco-friendly synthesis of TiO2, Au and Pt doped TiO2 nanoparticles for dye sensitized solar cell applications and evaluation of toxicity

    Science.gov (United States)

    Gopinath, K.; Kumaraguru, S.; Bhakyaraj, K.; Thirumal, S.; Arumugam, A.

    2016-04-01

    Driven by the demand of pure TiO2, Au and Pt doped TiO2 NPs were successfully synthesized using Terminalia arjuna bark extract. The eco-friendly synthesized NPs were characterized by UV-Vis-DRS, ATR-FT-IR, PL, XRD, Raman, SEM with EDX and TEM analysis. The synthesized NPs were investigation for dye sensitized solar cell applications. UV-Vis-Diffused Reflectance Spectra clearly showed that the expected TiO2 inter band absorption below 306 nm, incorporation of gold shows surface plasma resonant (SPR) near 555 nm and platinum incorporated TiO2 NPs shows absorbance at 460 nm. The energy conversion efficiency for Au doped TiO2 NPs when compared to pure and Pt doped TiO2 NPs. In addition to that, Au noble metal present TiO2 matrix and an improve open-circuit voltage (Voc) of DSSC. Synthesized NPs was evaluated into antibacterial and antifungal activities by disk diffusion method. It is observed that NPs have not shown any activities in all tested bacterial and fungal strains. In this eco-friendly synthesis method to provide non toxic and environmental friendly nanomaterials can be used for solar energy device application.

  12. An ac impedance study of the corrosion behaviour of mild steel coated with electrochemically synthesized polyoxyphenylenes

    Energy Technology Data Exchange (ETDEWEB)

    Musiani, M.M.; Mengoli, G.; Pagura, C.

    1985-04-01

    Electrochemically synthesized polyoxphenylene coatings on mild steel exposed to NaCl or H2SO4 solutions were investigated by ac impedance measurements. The influence of coating cohesion, adhesion to substrate, and surface pretreatment on the corrosion behaviour of the samples is clarified.

  13. TiO2 beads and TiO2-chitosan beads for urease immobilization

    International Nuclear Information System (INIS)

    Ispirli Doğaç, Yasemin; Deveci, İlyas; Teke, Mustafa; Mercimek, Bedrettin

    2014-01-01

    The aim of the present study is to synthesize TiO 2 beads for urease immobilization. Two different strategies were used to immobilize the urease on TiO 2 beads. In the first method (A), urease enzyme was immobilized onto TiO 2 beads by adsorption and then crosslinking. In the second method (B), TiO 2 beads were coated with chitosan-urease mixture. To determine optimum conditions of immobilization, different parameters were investigated. The parameters of optimization were initial enzyme concentration (0.5; 1; 1.5; 2 mg/ml), alginate concentration (1; 2; 3%), glutaraldehyde concentration (1; 2; 3% v/v) and chitosan concentration (2; 3; 4 mg/ml). The optimum enzyme concentrations were determined as 1.5 mg/ml for A and 1.0 mg/ml for B. The other optimum conditions were found 2.0% (w/v) for alginate concentration (both A and B); 3.0 mg/ml for chitosan concentration (B) and 2.0% (v/v) for glutaraldehyde concentration (A). The optimum temperature (20-60 °C), optimum pH (3.0-10.0), kinetic parameters, thermal stability (4–70 °C), pH stability (4.0-9.0), operational stability (0-230 min) and reusability (20 times) were investigated for characterization. The optimum temperatures were 30 °C (A), 40 °C (B) and 35 °C (soluble). The temperature profiles of the immobilized ureases were spread over a large area. The optimum pH values for the soluble urease and immobilized urease prepared by using methods (A) and (B) were found to be 7.5, 7.0, 7.0, respectively. The thermal stabilities of immobilized enzyme sets were studied and they maintained 50% activity at 65 °C. However, at this temperature free urease protected only 15% activity. - Highlights: • TiO 2 and TiO 2 -chitosan beads for urease immobilization have been prepared and characterized. • The beads used in this work are good matrices for the immobilization of urease. • The immobilized urease was shown to have good properties and stabilities (pH and thermal stability, operational stability). • The 50

  14. Improvement of light harvesting and device performance of dye-sensitized solar cells using rod-like nanocrystal TiO2 overlay coating on TiO2 nanoparticle working electrode

    International Nuclear Information System (INIS)

    Liu, Xueyang; Fang, Jian; Gao, Mei; Wang, Hongxia; Yang, Weidong; Lin, Tong

    2015-01-01

    Novel TiO 2 single crystalline nanorods were synthesized by electrospinning and hydrothermal treatment. The role of the TiO 2 nanorods on TiO 2 nanoparticle electrode in improvement of light harvesting and photovoltaic properties of dye-sensitized solar cells (DSSCs) was examined. Although the TiO 2 nanorods had lower dye loading than TiO 2 nanoparticle, they showed higher light utilization behaviour. Electron transfer in TiO 2 nanorods received less resistance than that in TiO 2 nanoparticle aggregation. By just applying a thin layer of TiO 2 nanorods on TiO 2 nanoparticle working electrode, the DSSC device light harvesting ability and energy conversion efficiency were improved significantly. The thickness of the nanorod layer in the working electrode played an important role in determining the photovoltaic property of DSSCs. An energy conversion efficiency as high as 6.6% was found on a DSSC device with the working electrode consisting of a 12 μm think TiO 2 nanoparticle layer covered with 3 μm thick TiO 2 nanorods. The results obtained from this study may benefit further design of highly efficient DSSCs. - Highlights: • Single crystalline TiO 2 nanorods were prepared for DSSC application. • TiO 2 nanorods show effective light scattering performance. • TiO 2 nanorods have higher electron transfer efficiency than TiO 2 nanoparticles. • TiO 2 nanorods on TiO 2 nanoparticle electrode improve DSSC efficiency

  15. Photocatalytic Decolorization Study of Methyl Orange by TiO2–Chitosan Nanocomposites

    Directory of Open Access Journals (Sweden)

    Imelda Fajriati

    2014-10-01

    Full Text Available The photocatalytic decolorization of methyl orange (MO by TiO2-chitosan nanocomposite has been studied. This study was started by synthesizing TiO2-chitosan nanocomposites using sol-gel method with various concentrations of Titanium(IV isopropoxide (TTIP as the TiO2 precursor. The structure, surface morphology, thermal and optical property of TiO2-chitosan nanocomposite were characterized by X-ray diffraction (XRD, fourier transform infra red (FTIR spectroscopy, scanning electron microscopy (SEM, thermogravimetric analysis (TGA, and diffuse reflectance ultra violet (DRUV spectroscopy. The photocatalytic activity of TiO2-chitosan nanocomposite was evaluated by photocatalytic decolorization of methyl orange as a model pollutant. The results indicate that the particle size of TiO2 increases with increasing ofthe concentration of TTIP, in which TiO2 with smallest particle size exhibit the highest photocatalytic activity. The highest photocatalytic decolorization was obtained at 5 h of contact time, initial concentration of MO at 20 ppm and at solution pH of 4. Using these conditions, over 90% of MO was able to be decolorized using 0.02 g of TiO2-chitosan nanocomposite under UV light irradiation. The TiO2-chitosan nanocomposite could be reused, which meant that the TiO2-chitosan nanocomposites can be developed as an effective and economical photocatalyst to decolorize or treat dye in wastewater.

  16. The Influence of NiO Addition in TiO2 Structure and Its Photoactivity

    Science.gov (United States)

    Wahyuningsih, S.; Ramelan, A. H.; Purwanti, P. D.; Munawaroh, H.; Ichsan, S.; Kristiawan, Y. R.

    2018-03-01

    The synthesis of TiO2 together with the TiO2-NiO composite using various annealing temperatures has been studied. The synthesis of TiO2 was performed by sol gel method using Titanium Tetra Isopropoxide (TTIP) precursor, whereas the synthesis of TiO2-NiO composite was done by wet impregnation method using NiNO3.6H2O precursor. This study aims to determine the influence of NiO addition in its structure and photoactivity. The diffraction of synthesized TiO2 at 400 °C temperature shows anatase TiO2 peak at 2θ = 25.35 °. The addition of NiO dopant to the synthesis of TiO2 process is carried out by annealing at 300 °C, 400 °C, 500 °C, 600 °C, and 700 °C, respectively. The TiO2-NiO composite has been prepared and shows the diffraction peak of NiO at 2θ=43° about 33.08 to 36.68%. The optimum result of Rhodamine B photodegradation with TiO2 was 43.15%, while the optimum result of Rhodamine B degradation with TiO2-NiO composite was 92.85%.

  17. Electrical conductivity characteristic of TiO2 nanowires from hydrothermal method

    International Nuclear Information System (INIS)

    Othman, Mohd Azlishah; Amat, Noor Faridah; Ahmad, Badrul Hisham; Rajan, Jose

    2014-01-01

    One dimensional nanostructures of titanium dioxide (TiO 2 ) were synthesized via hydrothermal method by mixing TiO 2 as precursor in aqueous solution of NaOH as solvent. Then, heat and washing treatment was applied. Thus obtained wires had diameter ∼15 nm. TiO 2 nanowires will be used as a network in solar cell such dye-sensitized solar cell in order to improve the performance of electron movement in the device. To improve the performance of electron movement, the characteristics of TiO 2 nanowires have been analyses using field emission scanning electron microscopy (FESEM) analysis, x-ray diffractometer (XRD) analysis and brunauer emmett teller (BET) analysis. Finally, electrical conductivity of TiO 2 nanowires was determined by measuring the resistance of the TiO 2 nanowires paste on microscope glass.

  18. Photodegradation of Reactive Golden Yellow R Dye Catalyzed by Effective Titania (TiO2)

    International Nuclear Information System (INIS)

    Bedurus, E.A.; Marinah Mohd Ariffin; Mohd Hasmizam Razali

    2015-01-01

    In the present research, Microwave Assisted Synthesis (MAS) method was applied to synthesize titania (TiO 2 ) at 150 degree Celsius in a range of 2-6 hours heating time. Each prepared TiO 2 were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and nitrogen gas (N 2 ) sorption analysis (Brunaeur-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) calculation) techniques. The TiO 2 prepared by MAS 150 degree Celsius (4 hours) has emerged with the highest photo catalytic activity. Within 4 hours, the TiO 2 managed to catalyze the degradation of Reactive Golden Yellow R dye up to 98.51 %. This is because of the TiO 2 possessed high crystallinity of anatase phase, small crystallite size and high pore volume compared to other prepared TiO 2 . (author)

  19. Flow-Regulated Growth of Titanium Dioxide (TiO2 ) Nanotubes in Microfluidics.

    Science.gov (United States)

    Fan, Rong; Chen, Xinye; Wang, Zihao; Custer, David; Wan, Jiandi

    2017-08-01

    Electrochemical anodization of titanium (Ti) in a static, bulk condition is used widely to fabricate self-organized TiO 2 nanotube arrays. Such bulk approaches, however, require extended anodization times to obtain long TiO 2 nanotubes and produce only vertically aligned nanotubes. To date, it remains challenging to develop effective strategies to grow long TiO 2 nanotubes in a short period of time, and to control the nanotube orientation. Here, it is shown that the anodic growth of TiO 2 nanotubes is significantly enhanced (≈16-20 times faster) under flow conditions in microfluidics. Flow not only controls the diameter, length, and crystal orientations of TiO 2 nanotubes, but also regulates the spatial distribution of nanotubes inside microfluidic devices. Strikingly, when a Ti thin film is deposited on silicon substrates and anodized in microfluidics, both vertically and horizontally aligned (relative to the bottom substrate) TiO 2 nanotubes can be produced. The results demonstrate previously unidentified roles of flow in the regulation of growth of TiO 2 nanotubes, and provide powerful approaches to effectively grow long, oriented TiO 2 nanotubes, and construct hierarchical TiO 2 nanotube arrays on silicon-based materials. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Morphology and electrical properties of electrochemically synthesized pyrrole–formyl pyrrole copolymer

    Energy Technology Data Exchange (ETDEWEB)

    Gholami, Mehrdad, E-mail: mehrdad897@um.edu.my [Department of Chemistry, University of Malaya, Kuala Lumpur 50603 (Malaysia); Department of Chemistry, Marvdasht Branch, Islamic Azad University, P.O. Box 465, Marvdasht (Iran, Islamic Republic of); Nia, Pooria Moozarm, E-mail: pooriamn@yahoo.com [Department of Chemistry, University of Malaya, Kuala Lumpur 50603 (Malaysia); Alias, Yatimah, E-mail: yatimah70@um.edu.my [Department of Chemistry, University of Malaya, Kuala Lumpur 50603 (Malaysia)

    2015-12-01

    Graphical abstract: - Highlights: • The (Py–co-FPy) copolymer was synthesized electrochemically. • This copolymer has 1.6 times higher surface coverage compared to polypyrrole. • This copolymer showed 2.5 times lower resistance compared to polypyrrole. • The conjugated structure between Py and FPy causes enhancement of conductivity. • This conducting copolymer has a strong potential to be used in various applications. - Abstract: A direct electrochemical copolymerization of pyrrole–formyl pyrrole (Py–co-FPy) was carried out by oxidative copolymerization of formyl pyrrole and pyrrole in LiClO{sub 4} aqueous solution through galvanostatic method. The (Py–co-FPy) copolymer was characterized using Fourier-transform infrared spectroscopy (FT-IR), field emission scanning electron microscope (FESEM), energy-filtering transmission electron microscope (EFTEM), thermal gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The FESEM images showed that the synthesized copolymer had a hollow whelk-like helixes structure, which justifies the enhancement of charge transportation through the copolymer film. Cyclic voltammetry studies revealed that the electrocatalytic activity of synthesized copolymer has improved and the surface coverage in copolymer enhanced 1.6 times compared to polypyrrole alone. Besides, (Py–co-FPy) copolymer showed 2.5 times lower electrochemical charge transfer resistance (R{sub ct}) value in impedance spectroscopy. Therefore, this copolymer has a strong potential to be used in several applications such as sensor applications.

  1. Electrochemical Hydrogen Storage in Facile Synthesized Co@N-Doped Carbon Nanoparticle Composites.

    Science.gov (United States)

    Zhou, Lina; Qu, Xiaosheng; Zheng, Dong; Tang, Haolin; Liu, Dan; Qu, Deyang; Xie, ZhiZhong; Li, Junsheng; Qu, Deyu

    2017-11-29

    A Co@nitrogen-doped carbon nanoparticle composite was synthesized via a facile molecular self-assembling procedure. The material was used as the host for the electrochemical storage of hydrogen. The hydrogen storage capacity of the material was over 300 mAh g -1 at a rate of 100 mAg -1 . It also exhibited superior stability for storage of hydrogen, high rate capability, and good cyclic life. Hybridizing metallic cobalt nanoparticle with nitrogen-doped mesoporous carbon is found to be a good approach for the electrochemical storage of hydrogen.

  2. Effect of TiO2 on the Gas Sensing Features of TiO2/PANi Nanocomposites

    Directory of Open Access Journals (Sweden)

    Duong Ngoc Huyen

    2011-02-01

    Full Text Available A nanocomposite of titanium dioxide (TiO2 and polyaniline (PANi was synthesized by in-situ chemical polymerization using aniline (ANi monomer and TiCl4 as precursors. SEM pictures show that the nanocomposite was created in the form of long PANi chains decorated with TiO2 nanoparticles. FTIR, Raman and UV-Vis spectra reveal that the PANi component undergoes an electronic structure modification as a result of the TiO2 and PANi interaction. The electrical resistor of the nanocomposite is highly sensitive to oxygen and NH3 gas, accounting for the physical adsorption of these gases. A nanocomposite with around 55% TiO2 shows an oxygen sensitivity of 600–700%, 20–25 times higher than that of neat PANi. The n-p contacts between TiO2 nanoparticles and PANi matrix give rise to variety of shallow donors and acceptor levels in the PANi band gap which enhance the physical adsorption of gas molecules.

  3. Enhanced photocatalytic activity of wool-ball-like TiO2 microspheres on carbon fabric and FTO substrates

    Science.gov (United States)

    Zhang, Yu; Gu, Jian; Zhang, Mengqi

    2018-06-01

    The wool-ball-like TiO2 microspheres on carbon fabric (TiO2-CF) and FTO substrates (TiO2-FTO) have been synthesized by a facile hydrothermal method in alkali environment, using commercial TiO2 (P25) as precursors. The XRD results indicate that the as-prepared TiO2 have good crystallinity. And the SEM images show that the wool-ball-like TiO2 microspheres with a diameter of 2-3 μm are composed of TiO2 nanowires, which have a diameter of 50 nm. The photocatalytic behavior of the wool-ball-like TiO2 microspheres, TiO2-CF and TiO2-FTO under ultraviolet light was investigated by a pseudo first-order kinetic model, using methyl orange (MO) as pollutant. The wool-ball-like TiO2 microspheres obtained a degradation rate constant (Kap) of 6.91×10-3 min-1 . The Kap values of TiO2-FTO and TiO2-CF reach 13.97×10-3 min-1 and 11.80×10-3 min-1, which are 2.0 and 1.7 times higher than that of pristine wool-ball-like TiO2 microspheres due to the "sum effect" between TiO2 and substrates. This study offers a facile hydrothermal method to prepare wool-ball-like TiO2 microspheres on CF and FTO substrates, which will improve the recyclability of phtocatalysts and can be extended to other fields.

  4. Synergistic effects between TiO2 and carbon nanotubes (CNTs) in a TiO2/CNTs system under visible light irradiation.

    Science.gov (United States)

    Wu, Chung-Hsin; Kuo, Chao-Yin; Chen, Shih-Ting

    2013-01-01

    This study synthesized a TiO2/carbon nanotubes (CNTs) composite via the sol-gel method. The surface characteristics of the TiO2/CNTs composite were determined by X-ray diffraction, transmission electron microscopy, specific surface area analyser, ultraviolent (UV)-vis spectroscopy, X-ray photoelectron spectroscopy and Raman spectrometer. The photocatalytic activity ofthe TiO2/CNTs composite was evaluated by decolourizing C.I. Reactive Red 2 (RR2) under visible light irradiation. Furthermore, the effects of calcination temperature, pH, RR2 concentration, and the TiO2/CNTs composite dosage on RR2 decolourization were determined simultaneously. The optimal calcination temperature to generate TiO2 and the TiO2/CNTs composite was 673 K, as the percentage of anatase crystallization at this temperature was highest. The specific surface area of the TiO2/CNTs composite and TiO2 were 45 and 42 m2/g, respectively. The band gap of TiO2 and the TiO2/CNTs composite was 2.97 and 2.71 eV by UV-vis measurements, respectively. Experimental data indicate that the Ti-O-C bond formed in the TiO2/CNTs composite. The RR2 decolourization rates can be approximated by pseudo-first-order kinetics; moreover, only the TiO2/CNTs composite had photocatalytic activity under visible light irradiation. At pH 7, the RR2 decolourization rate constant of 0.5, 1 and 2 g/L TiO2/CNTs addition was 0.005, 0.0015, and 0.0047 min(-1), respectively. Decolourization rate increased as pH and the RR2 concentration decreased. The CNTs functioned as electron acceptors, promoting separation of photoinduced electron-hole pairs to retard their recombination; thus, photocatalytic activity of the TiO2/CNTs composite exceeded that of TiO2.

  5. Anti-fish bacterial pathogen effect of visible light responsive Fe3O4@TiO2 nanoparticles immobilized on glass using TiO2 sol–gel

    International Nuclear Information System (INIS)

    Yeh, N.; Lee, Y.C.; Chang, C.Y.; Cheng, T.C.

    2013-01-01

    This paper demonstrates a fish pathogen reduction procedure that uses TiO 2 sol–gel coating Fe 3 O 4 @TiO 2 powder on glass substrate. Such procedure can effectively relieve two constraints that haunt TiO 2 sterilization applications: 1) the need for UV for overcoming the wide band gap of pure TiO 2 and 2) the difficulty of its recovering from water for reuse. In the process, visible light responsive Fe 3 O 4 /TiO 2 nanoparticles are synthesized and immobilized on glass using TiO 2 sol–gel as the binder for fish bacterial pathogen disinfection test. After 3 h of visible light irradiation, the immobilized Fe 3 O 4 @TiO 2 's inhibition efficiencies for fish bacterial pathogen are, respectively, 50% for Edwardsiella tarda (BCRC 10670) and 23% for Aeromonas hydrophila (BCRC 13018)

  6. Engineering the TiO2 -graphene interface to enhance photocatalytic H2 production.

    Science.gov (United States)

    Liu, Lichen; Liu, Zhe; Liu, Annai; Gu, Xianrui; Ge, Chengyan; Gao, Fei; Dong, Lin

    2014-02-01

    In this work, TiO2 -graphene nanocomposites are synthesized with tunable TiO2 crystal facets ({100}, {101}, and {001} facets) through an anion-assisted method. These three TiO2 -graphene nanocomposites have similar particle sizes and surface areas; the only difference between them is the crystal facet exposed in TiO2 nanocrystals. UV/Vis spectra show that band structures of TiO2 nanocrystals and TiO2 -graphene nanocomposites are dependent on the crystal facets. Time-resolved photoluminescence spectra suggest that the charge-transfer rate between {100} facets and graphene is approximately 1.4 times of that between {001} facets and graphene. Photoelectrochemical measurements also confirm that the charge-separation efficiency between TiO2 and graphene is greatly dependent on the crystal facets. X-ray photoelectron spectroscopy reveals that Ti-C bonds are formed between {100} facets and graphene, while {101} facets and {001} facets are connected with graphene mainly through Ti-O-C bonds. With Ti-C bonds between TiO2 and graphene, TiO2 -100-G shows the fastest charge-transfer rate, leading to higher activity in photocatalytic H2 production from methanol solution. TiO2 -101-G with more reductive electrons and medium interfacial charge-transfer rate also shows good H2 evolution rate. As a result of its disadvantageous electronic structure and interfacial connections, TiO2 -001-G shows the lowest H2 evolution rate. These results suggest that engineering the structures of the TiO2 -graphene interface can be an effective strategy to achieve excellent photocatalytic performances. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Synthesis and characterization of Ag-doped TiO2 nanotubes on Ti-6Al-4V and Ti-6Al-7Nb alloy

    Science.gov (United States)

    Ulfah, Ika Maria; Bachtiar, Boy M.; Murnandityas, Arnita Rut; Slamet

    2018-05-01

    The present paper is focused on comparative behavior of nanotubes growth on Ti-6Al-4V and Ti-6Al-7Nb alloy using electrochemical anodization method. These alloys were anodized in electrolytes solution containing glycerol, water and 0.5wt.% of NH4F. Silver-doped TiO2 nanotubes were synthesized using photo-assisted deposition (PAD) at various Ag loading concentration in 0.05 M, 0.10 M, and 0.15 M. The phase composition and morphological characteristics were investigated by XRD and FESEM/EDX, respectively. The surface wettability was measured by contact angle meter. The results showed that TiO2 nanotubes can be grown on these surface alloys. XRD profiles revealed crystal formation of anatase, rutile and Ag on these surface alloys. According to FESEM images, the average nanotube diameter of Ti-6Al-4V alloy and Ti-6Al-7Nb alloy are 134 nm and 120 nm, respectively. EDX-Mapping analysis showed that Ag desposited over surface of TiO2 nanotubes. The surface wettability indicated hydrophilicity properties on Ti-4Al-4V alloy and Ti-6Al-7Nb alloy surface. This study may contribute to the development of silver-doped TiO2 nanotubes on Ti-6Al-4V alloy and Ti-6Al-7Nb alloy can be considered in various photocatalytic applications such as biomedical devicesdue to photocatalytic mechanism and antibacterial ability.

  8. Effect of TiO_2 Loading on Pt-Ru Catalysts During Alcohol Electrooxidation

    International Nuclear Information System (INIS)

    Hasa, Bjorn; Kalamaras, Evangelos; Papaioannou, Evangelos I.; Vakros, John; Sygellou, Labrini; Katsaounis, Alexandros

    2015-01-01

    Highlights: • TiO_2 can be used to modify Pt-Ru based electrodes for alcohol oxidation. • TiO_2 modified electrodes with lower amount of metals had higher active surface area than pure Pt-Ru electrodes. • TiO_2 modified electrodes showed comparable performance with pure Pt-Ru electrode both in a single cell and in a PEM fuel cell under alcohol fuelling. - Abstract: In this study, Pt-Ru based electrodes modified by TiO_2 were prepared by means of thermal decomposition of chloride and isopropoxide precursors on Ti substrates, characterised by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), electrochemical techniques and CO stripping and used as anodes for alcohol oxidation. The minimization of the metal loading without electrocatalytic activity losses was also explored. TiO_2 was chosen due to its chemical stability, low cost and excellent properties as substrate for metal dispersion. It was found that TiO_2 loading up to 50% results in a 3-fold increase of the Electrochemically Active Surface (EAS). This conclusion has been confirmed by CO stripping experiments. All samples have been evaluated during the electrochemical oxidation of methanol, ethanol and glycerol. In all cases, the Pt_2_5-Ru_2_5-(TiO_2)_5_0 electrode had better electrocatalytic activity than the pure Pt_5_0-Ru_5_0 anode. The best modified electrode, (Pt_2_5-Ru_2_5-(TiO_2)_5_0), was also evaluated as anode in a PEM fuel cell under methanol fuelling conditions. The observed higher performance of the TiO_2 modified electrodes was attributed to the enhanced Pt-Ru dispersion as well as the formation of smaller Pt and Ru particles.

  9. Fullerene C70 decorated TiO2 nanowires for visible-light-responsive photocatalyst

    International Nuclear Information System (INIS)

    Cho, Er-Chieh; Ciou, Jing-Hao; Zheng, Jia-Huei; Pan, Job; Hsiao, Yu-Sheng; Lee, Kuen-Chan; Huang, Jen-Hsien

    2015-01-01

    Graphical abstract: - Highlights: • TiO 2 nanowire decorated with C 60 and C 70 derivatives has been synthesized. • The fullerenes impede the charge recombination due to its high electron affinity. • The fullerenes expand the utilization of solar light from UV to visible light. • The modified-TiO 2 has great biocompatibility. - Abstract: In this study, we have synthesized C 60 and C 70 -modified TiO 2 nanowire (NW) through interfacial chemical bonding. The results indicate that the fullerenes (C 60 and C 70 derivatives) can act as sinks for photogenerated electrons in TiO 2 , while the fullerene/TiO 2 is illuminated under ultraviolet (UV) light. Therefore, in comparison to the pure TiO 2 NWs, the modified TiO 2 NWs display a higher photocatalytic activity under UV irradiation. Moreover, the fullerenes also can function as a sensitizer to TiO 2 which expand the utilization of solar light from UV to visible light. The results reveal that the C 70 /TiO 2 NWs show a significant photocatalytic activity for degradation of methylene blue (MB) in visible light region. To better understand the mechanism responsible for the effect of fullerenes on the photocatalytic properties of TiO 2 , the electron only devices and photoelectrochemical cells based on fullerenes/TiO 2 are also fabricated and evaluated.

  10. Enhanced electrochromic properties of TiO2 nanoporous film prepared based on an assistance of polyethylene glycol

    Science.gov (United States)

    Xu, Shunjian; Luo, Xiaorui; Xiao, Zonghu; Luo, Yongping; Zhong, Wei; Ou, Hui; Li, Yinshuai

    2017-01-01

    Polyethylene glycol (PEG) was employed as pore-forming agent to prepare TiO2 nanoporous film based on spin-coating a TiO2 nanoparticle mixed paste on fluorine doped tin oxide (FTO) glass. The electrochromic and optical properties of the obtained TiO2 film were investigated by cyclic voltammetry (CV), chronoamperometry (CA) and UV-Vis spectrophotometer. The results show that the PEG in the mixed paste endows the TiO2 film with well-developed porous structure and improves the uniformity of the TiO2 film, which are helpful for the rapid intercalation and extraction of lithium ions within the TiO2 film and the strengthening of the diffuse reflection of visible light in the TiO2 film. As a result, the TiO2 film derived from the mixed paste with PEG displays higher electrochemical activity and more excellent electrochromic performances compared with the TiO2 film derived from the mixed paste without PEG. The switching times of coloration/bleaching are respectively 10.16/5.65 and 12.77/6.13 s for the TiO2 films with PEG and without PEG. The maximum value of the optical contrast of the TiO2 film with PEG is 21.2% while that of the optical contrast of the TiO2 film without PEG is 14.9%. Furthermore, the TiO2 film with PEG has better stability of the colored state than the TiO2 film without PEG.

  11. Glycine assisted synthesis of flower-like TiO2 hierarchical spheres and its application in photocatalysis

    International Nuclear Information System (INIS)

    Tao, Yu-gui; Xu, Yan-qiu; Pan, Jun; Gu, Hao; Qin, Chang-yun; Zhou, Peng

    2012-01-01

    Graphical abstract: Flower-like anatase TiO 2 hierarchical spheres assembled by nanosheets were synthesized by glycine assistant via a simple hydrothermal approach and after-annealing process. The obtained TiO 2 sample showed good photocatalytic activity of decomposition of methyl orange under sunlight. Highlights: ► Flower-like TiO 2 hierarchical spheres were synthesized by glycine assistant. ► Reaction time, temperature, solution pH and glycine dosage were studied. ► The formation of the flower-like TiO 2 spheres is an Ostwald ripening process. ► Flower-like TiO 2 showed high photocatalytic activity under sunlight. - Abstract: Flower-like anatase TiO 2 hierarchical spheres assembled by nanosheets were synthesized by glycine assistant via a simple hydrothermal approach and after-annealing process. These flower-like spheres are about 2 μm in diameter with sheet thickness about 20 nm. Results showed reaction time, temperature, solution pH and glycine dosage all played an important role in control of shape and size of the as-synthesized TiO 2 nanocrystals. The photocatalytic activity of this nano-TiO 2 was evaluated by the photocatalytic oxidation decomposition of methyl orange under sunlight illumination in the presence of hydrogen peroxide (H 2 O 2 ). The photocatalytic activity of the obtained TiO 2 was higher than that of commercial TiO 2 .

  12. Effects of Homogenization Scheme of TiO2 Screen-Printing Paste for Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Seigo Ito

    2012-01-01

    Full Text Available TiO2 porous electrodes have been fabricated for photoelectrodes in dye-sensitized solar cells (DSCs using TiO2 screen-printing paste from nanocrystalline TiO2 powder dried from the synthesized sol. We prepared the TiO2 screen-printing paste by two different methods to disperse the nanocrystalline TiO2 powder: a “ball-milling route” and a “mortal-grinding route.” The TiO2 ball-milling (TiO2-BM route gave monodisperse TiO2 nanoparticles, resulting in high photocurrent density (14.2 mA cm−2 and high photoconversion efficiency (8.27%. On the other hand, the TiO2 mortal-grinding (TiO2-MG route gave large aggregate of TiO2 nanoparticles, resulting in low photocurrent density (11.5 mA cm−2 and low photoconversion efficiency (6.43%. To analyze the photovoltaic characteristics, we measured the incident photon-to-current efficiency, light absorption spectroscopy, and electrical impedance spectroscopy of DSCs.

  13. TiO2-B Nanoribbons Anchored with NiO Nanosheets as Hybrid Anode Materials for Rechargeable Lithium ion Batteries

    DEFF Research Database (Denmark)

    Zhang, J. Y.; Shen, J.X.; Wang, T.L.

    2015-01-01

    A new type of TiO2-B nanoribbon anchored with NiO nanosheets (TiO2@NiO) is synthesized via a hydrothermal process and a subsequent homogeneous precipitation method. XRD analysis indicates that TiO2-B and cubic NiO phases exist in the composites. According to SEM images, the morphology of the TiO2...

  14. The Influence of Cr3+ on TiO2 Crystal Growth and Photoactivity Properties

    Science.gov (United States)

    Wahyuningsih, S.; Hidayatika, W. N.; Sari, P. L.; Sari, P. P.; Hidayat, R.; Munawaroh, H.; Ramelan, A. H.

    2018-03-01

    The photocatalyst technology is an integrated combination of photochemical processes and catalysis in order to carry out a chemical transformation reaction. One of the semiconductor materials that have good photocatalytic activity is TiO2 anatase. This study aim to determine the effect of the Cr3+ addition on the growth of TiO2 rutile crystal and the increasing of TiO2 photoactivity. Diffractogram X-Ray of the samples showed that the synthesized TiO2 at 400 °C has been produced 100% TiO2 anatase. Synthesis of TiO2 doped Cr3+ composite was using wet impregnation method. The TiO2 doped Cr3+ composites have beed grown by annealed at a temperature of 300, 400, 500, 600 and 700 °C, respectively Annealing process have capabled to gain to the TiO2 doped Cr3+ nanocomposite. The result product annealed at 500 °C only appear anatase phase due to the Cr3+ addition influence that was able to suppress the growth of rutile. Identification of TiO2 doped Cr3+ composite using Fourier Transform Infra-Red (FT-IR) showed O-Cr vibration at 2283.72 cm-1. The TiO2 doped Cr3+ photoactivity was studied to degrade Rhodamin B. The best result on photodegradation of Rhodamin B was performed by using TiO2 doped Cr3+ composite which was annealed at 700 °C i.e. 74.71%.

  15. Characterization and improved solar light activity of vanadium doped TiO2/diatomite hybrid catalysts

    International Nuclear Information System (INIS)

    Wang, Bin; Zhang, Guangxin; Leng, Xue; Sun, Zhiming; Zheng, Shuilin

    2015-01-01

    Highlights: • V-doped TiO 2 /diatomite composite photocatalyst was synthesized. • The physiochemical property and solar light photoactivity were characterized. • The presence and influence of V ions in TiO 2 matrix was systematically analyzed. • The photocatalysis for Rhodamine B were studied under solar light illumination. - Abstract: V-doped TiO 2 /diatomite composite photocatalysts with different vanadium concentrations were synthesized by a modified sol–gel method. The diatomite was responsible for the well dispersion of TiO 2 nanoparticles on the matrix and consequently inhibited the agglomeration. V-TiO 2 /diatomite hybrids showed red shift in TiO 2 absorption edge with enhanced absorption intensity. Most importantly, the dopant energy levels were formed in the TiO 2 bandgap due to V 4+ ions substituted to Ti 4+ sites. The 0.5% V-TiO 2 /diatomite photocatalyst displayed narrower bandgap (2.95 eV) compared to undoped sample (3.13 eV) and other doped samples (3.05 eV) with higher doping concentration. The photocatalytic activities of V doped TiO 2 /diatomite samples for the degradation of Rhodamine B under stimulated solar light illumination were significantly improved compared with the undoped sample. In our case, V 4+ ions incorporated in TiO 2 lattice were responsible for increased visible-light absorption and electron transfer to oxygen molecules adsorbed on the surface of TiO 2 to produce superoxide radicals ·O 2 – , while V 5+ species presented on the surface of TiO 2 particles in the form of V 2 O 5 contributed to e – –h + separation. In addition, due to the combination of diatomite as support, this hybrid photocatalyst could be separated from solution quickly by natural settlement and exhibited good reusability

  16. Efficient photodecomposition of herbicide imazapyr over mesoporous Ga2O3-TiO2 nanocomposites.

    Science.gov (United States)

    Ismail, Adel A; Abdelfattah, Ibrahim; Faisal, M; Helal, Ahmed

    2018-01-15

    The unabated release of herbicide imazapyr into the soil and groundwater led to crop destruction and several pollution-related concerns. In this contribution, heterogeneous photocatalytic technique was employed utilizing mesoporous Ga 2 O 3 -TiO 2 nanocomposites for degrading imazapyr herbicide as a model pollutant molecule. Mesoporous Ga 2 O 3 -TiO 2 nanocomposites with varied Ga 2 O 3 contents (0-5wt%) were synthesized through sol-gel process. XRD and Raman spectra exhibited extremely crystalline anatase TiO 2 phase at low Ga 2 O 3 content which gradually reduced with the increase of Ga 2 O 3 content. TEM images display uniform TiO 2 particles (10±2nm) with mesoporous structure. The mesoporous TiO 2 exhibits large surface areas of 167m 2 g -1 , diminished to 108m 2 g -1 upon 5% Ga 2 O 3 incorporation, with tunable mesopore diameter in the range of 3-9nm. The photocatalytic efficiency of synthesized Ga 2 O 3 -TiO 2 nanocomposites was assessed by degrading imazapyr herbicide and comparing with commercial photocatalyst UV-100 and mesoporous Ga 2 O 3 under UV illumination. 0.1% Ga 2 O 3 -TiO 2 nanocomposite is considered the optimum photocatalyst, which degrades 98% of imazapyr herbicide within 180min. Also, the photodegradation rate of imazapyr using 0.1% Ga 2 O 3 -TiO 2 nanocomposite is nearly 10 and 3-fold higher than that of mesoporous Ga 2 O 3 and UV-100, respectively. The high photonic efficiency and long-term stability of the mesoporous Ga 2 O 3 -TiO 2 nanocomposites are ascribed to its stronger oxidative capability in comparison with either mesoporous TiO 2 , Ga 2 O 3 or commercial UV-100. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Electrochemical performance of Si-multiwall carbon nanotube nanocomposite anode synthesized by thermal plasma

    Energy Technology Data Exchange (ETDEWEB)

    Na, Ye-Seul; Yoo, Hyeonseok; Kim, Tae-Hee; Choi, Jinsub; Lee, Wan In; Choi, Sooseok, E-mail: sooseok@jejunu.ac.kr; Park, Dong-Wha, E-mail: dwpark@inha.ac.kr

    2015-07-31

    Lithium-ion (Li-ion) batteries are widely used in electric devices and vehicles. Silicon is a promising material for the anode of Li-ion battery due to high theoretical specific capacity. However, it shows large volume changes during charge–discharge cycles leading to the pulverization of electrode. In order to improve such disadvantage, a multiwall carbon nanotube (MWCNT) has been used with silicon as composite material. In this work, Si-MWCNT nanocomposite was prepared in thermal plasma by attaching silicon nanoparticles to MWCNT column. Electrochemical tests for raw materials and synthesized nanocomposites were carried out. The discharge capacities of silicon, MWCNT, synthesized nanocomposites collected from a reaction tube, and a chamber were 4000, 310, 200, and 1447 mAh/g, respectively. - Highlights: • Si-Multiwall carbon nanotube nanocomposite was synthesized by thermal plasma. • The effect on the collection position of product after experiment was examined. • Cycle performance of electrodes was measured. • Product collected from chamber showed good electrochemical performance.

  18. Nickel oxide/hydroxide nanoplatelets synthesized by chemical precipitation for electrochemical capacitors

    International Nuclear Information System (INIS)

    Wu, M.-S.; Hsieh, H.-H.

    2008-01-01

    Nickel hydroxide powder prepared by directly chemical precipitation method at room temperature has a nanoplatelet-like morphology and could be converted into nickel oxide at annealing temperature higher than 300 deg. C, confirmed by the thermal gravimetric analysis and X-ray diffraction. Annealing temperature influences significantly both the electrical conductivity and the specific surface area of nickel oxide/hydroxide powder, and consequently determines the capacitor behavior. Electrochemical capacitive behavior of the synthesized nickel hydroxide/oxide film is investigated by cyclic voltammetry and electrochemical impedance spectroscope methods. After 300 deg. C annealing, the highest specific capacitance of 108 F g -1 is obtained at scan rate of 10 mV s -1 . When annealing temperature is lower than 300 deg. C, the electrical conductivity of nickel hydroxide dominates primarily the capacitive behavior. When annealing temperature is higher than 300 deg. C, both electrical conductivity and specific surface area of the nickel oxide dominate the capacitive behavior

  19. SiO2@TiO2 Coating: Synthesis, Physical Characterization and Photocatalytic Evaluation

    Directory of Open Access Journals (Sweden)

    A. Rosales

    2018-03-01

    Full Text Available Use of silicon dioxide (SiO2 and titanium dioxide (TiO2 have been widely investigated individually in coatings technology, but their combined properties promote compatibility for different innovative applications. For example, the photocatalytic properties of TiO2 coatings, when exposed to UV light, have interesting environmental applications, such as air purification, self-cleaning and antibacterial properties. However, as reported in different pilot projects, serious durability problems, associated with the adhesion between the substrate and TiO2, have been evidenced. Thus, the aim of this work is to synthesize SiO2 together with TiO2 to increase the durability of the photocatalytic coating without affecting its photocatalytic potential. Therefore, synthesis using sonochemistry, synthesis without sonochemistry, physical characterization, photocatalytic evaluation, and durability of the SiO2, SiO2@TiO2 and TiO2 coatings are presented. Results indicate that using SiO2 improved the durability of the TiO2 coating without affecting its photocatalytic properties. Thus, this novel SiO2@TiO2 coating shows potential for developing long-lasting, self-cleaning and air-purifying construction materials.

  20. The Effects of Leaching Process to the TiO2 Synthesis from Bangka Ilmenite

    Science.gov (United States)

    Wahyuningsih, S.; Ramelan, A. H.; Pramono, E.; Argawan, P.; Djatisulistya, A.; Firdiyono, F.; Sulistiyono, E.; Sari, P. P.

    2018-03-01

    Ilmenite mineral is a naturally occurring iron titanate (FeTiO3) and is abundant in nature. The separation of components into TiO2 and Fe2O3 must be expand. The purpose of this research is to synthesis TiO2 nanoparticles from the filtrate of Bangka ilmenite leaching process. Leaching of ilmenite was done with H2SO4 and HCl at various concentrations. The formation of TiO2 crystal determined by hydrolysis conditions and condensation reaction. TiO2 synthesized from the filtrate of sulfuric acid leaching that produced from TiO2 anatase phase when hydrolyzed in an aquaregia solvent and low concentrations of HCl (0.1M). Hydrolysis conditions at higher concentrations of HCl (1M) was produced TiO2 anatase-rutile phase. The synthesis of TiO2 from the filtrate of hydrochloric acid leaching was produced anatase phase. While the condition under the alcoholic solvent (2-propanol: H2O (v/v) = 9: 1) anatase phase crystallites grow in the temperature range up to 550 °C, above this temperature, TiO2 transform into rutile phase.

  1. Complex impedance study on nano-CeO2 coating TiO2

    International Nuclear Information System (INIS)

    Zhang Mei; Wang Honglian; Wang Xidong; Li Wenchao

    2006-01-01

    Titanium dioxide (TiO 2 ) nanoparticles and cerium dioxide (CeO 2 ) nanoparticles coated titanium dioxide (TiO 2 ) nanoparticles (CeO 2 -TiO 2 nanoparticles) have been successfully synthesized by sol-gel method. The complex impedance of the materials was investigated. The grain resistance, boundary resistance and activation energy of the nanoparticles were calculated according to Arrhenius equation. According to calculating results, the active capacity of pure TiO 2 nanoparticles has been improved because of nano-CeO 2 coating. An optimal CeO 2 content of 4.9 mol% was achieved. The high resolution electron microscopy images of CeO 2 -TiO 2 nanoparticles showed that TiO 2 nanoparticles, as a core, were covered by CeO 2 nanoparticles. The average size of CeO 2 coating TiO 2 nanoparticles was about 70 nm. Scanning electron microscopy observation indicted that CeO 2 nanoparticle coating improved the separation, insulation, and stability the CeO 2 -TiO 2 nanoparticles, which was benefit to the activity of materials

  2. Sensing and electrical properties of TiO2 nanoparticles

    International Nuclear Information System (INIS)

    Usman, M.

    2011-01-01

    The purpose of this work was to synthesize TiO 2 nanoparticles using Coprecipitation method. 2 different samples were synthesized, one with a modifier and other without using a modifier. After synthesis, newly formed nanoparticles were characterized b different techniques to find various properties of these nanoparticles. Scanning electron Microscopy (SEM) was used to study structure and morphology of Cu nanoparticles and for compositional analysis Energy dispersive spectroscopy (EDS) was used. X-Ray Diffraction (XRD) Studies were also carried out to find phase an average particle Size. To find the band gap of our nanoparticles, UV-Visible Spectroscopy was also done. Non-Modified nanoparticles were as small as 12nm reported by SEM images which were synthesized using a modifier were as small as 10nm. Modified TiO 2 nanoparticles were used in humidity sensing devices and it properties as a humidity sensor were examined by doing Impedance spectroscopy, D measurements and Dielectric measurements. Our TiO 2 humidity sensor showed sensitivity for humidity at low and mid-range frequencies while its response time was 4 seconds when we changed RH% to 90 from 40% and measured the impedance. (author)

  3. Synthesis and photocatalytic activity of mesoporous – (001) facets TiO_2 single crystals

    International Nuclear Information System (INIS)

    Dong, Yeshuo; Fei, Xuening; Zhou, Yongzhu

    2017-01-01

    Highlights: • The (001) facets of TiO_2 single crystals with mesoporous structure. • The (010) and (100) facets of TiO_2 single crystals were covered by the flower – shaped TiO_2 crystals. • This special structure could promote charge separation and provide more active sites, which will lead to a substantial increase in photocatalytic activity. - Abstract: In this work, the mesoporous – (001) facets TiO_2 single crystals have been successfully synthesized through a two-step solvothermal route without any template. Their structure and morphology were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible (UV–vis) diffuse reflectance spectroscopy and energy dispersive X-ray spectrometer (EDX). Based on the different characteristics and atomic arrangements on each facet of anatase TiO_2 single crystals, we synthesized these mesoporous – (001) facets TiO_2 single crystals by controlling the interaction characteristics of hydrofluoric acid (HF) and isopropanol (i-PrOH) on the crystal facets. It can been seen that the (001) facets of these as-synthesized TiO_2 single crystals have a clear mesoporous structure through the SEM images and BET methods. Moreover, the other four facets were covered by the flower – shaped TiO_2 crystals with the generation of the mesoporous – (001) facets. This special and interesting morphology could promote charge separation and provide more active sites, which will lead to a substantial increase in photocatalytic activity. Moreover, it is more intuitive to reflect that the different crystal facets possess the different properties due to their atomic arrangement. Besides, according to the different synthetic routes, we proposed and discussed a plausible synthesis mechanism of these mesoporous – (001) facets TiO_2 single crystals.

  4. Decolorization of dyeing wastewater in continuous photoreactors using tio2 coated glass tube media

    Directory of Open Access Journals (Sweden)

    Jutaporn Chanathaworn

    2014-02-01

    Full Text Available The present study deals with a decolorization development of malachite green (MG dyeing wastewater using TiO2 thin films coated glass tube media in photoreactor. The TiO2 photocatalyst was synthesized by three methods: TTIP sol-gel, TiO2 powder-modified sol, and TiO2 powder suspension coating on raschig ring glass tube media and was investigated crystallinity phase by SEM, XRD, and AFM. Degradation kinetics of the dyeing wastewater by photocatalytic was carried out under UV light irradiation. The Langmuir first-order model provided the best fit to the experimental data. The catalyst prepared by powder suspension technique and coated on glass tube had given the highest of decolorization kinetics and efficiency. Continuous photoreactor packed with the TiO2 coating media was designed and proven to be the high effectiveness for MG dyeing degradation and stable throughout the recyclability test. The light intensity, dye solution flow rate, and TiO2 loading were the most important parameters that response to decolorization efficiency. The optimum condition of photo decolorization of MG dye solution can be obtained from RSM model. Effectiveness of the synthesized TiO2 thin films using suspension technique and the continuous photoreactor design were obtained with a great potential to be proven for wastewater treatment at industrial scale.

  5. Facile synthesis of porous TiO_2 photocatalysts using waste sludge as the template

    International Nuclear Information System (INIS)

    Wang, Xiaopeng; Huang, Shouqiang; Zhu, Nanwen; Lou, Ziyang; Yuan, Haiping

    2015-01-01

    Graphical abstract: Waste sludge is introduced to synthesize the waste sludge templated TiO_2 photocatalyst with porous structure, which possesses better photocatalytic activity compared to pure TiO_2. - Highlights: • Waste sludge is introduced to synthesize the TiO_2 photocatalyst. • Waste sludge templated TiO_2 sample possesses porous structure. • Waste sludge templated TiO_2 sample exhibits high photocatalytic activity. - Abstract: A resource utilization method of waste sludge is present by the synthesis of waste sludge templated TiO_2 photocatalysts. The organic materials in waste sludge are used as the pore-forming agents, and the transition metals included in the remaining waste sludge through calcination (WSC) can serve as the dopants for the WSC-TiO_2 (WSCT) photocatalyst. The visible and UV–visible light driven photocatalytic activities of WSCT are much better compared to those of pure TiO_2 and WSC, and it is originated from the higher light absorption property and the efficient electron–hole pair separation provided by waste sludge.

  6. Homogeneous growth of TiO2-based nanotubes on nitrogen-doped reduced graphene oxide and its enhanced performance as a Li-ion battery anode.

    Science.gov (United States)

    Mehraeen, Shayan; Taşdemir, Adnan; Gürsel, Selmiye Alkan; Yürüm, Alp

    2018-06-22

    The pursuit of a promising replacement candidate for graphite as a Li-ion battery anode, which can satisfy both engineering criteria and market needs has been the target of researchers for more than two decades. In this work, we have investigated the synergistic effect of nitrogen-doped reduced graphene oxide (NrGO) and nanotubular TiO 2 to achieve high rate capabilities with high discharge capacities through a simple, one-step and scalable method. First, nanotubes of hydrogen titanate were hydrothermally grown on the surface of NrGO sheets, and then converted to a mixed phase of TiO 2 -B and anatase (TB) by thermal annealing. Specific surface area, thermal gravimetric, structural and morphological characterizations were performed on the synthesized product. Electrochemical properties were investigated by cyclic voltammetry and cyclic charge/discharge tests. The prepared anode showed high discharge capacity of 150 mAh g -1 at 1 C current rate after 50 cycles. The promising capacity of synthesized NrGO-TB was attributed to the unique and novel microstructure of NrGO-TB in which long nanotubes of TiO 2 have been grown on the surface of NrGO sheets. Such architecture synergistically reduces the solid-state diffusion distance of Li + and increases the electronic conductivity of the anode.

  7. Homogeneous growth of TiO2-based nanotubes on nitrogen-doped reduced graphene oxide and its enhanced performance as a Li-ion battery anode

    Science.gov (United States)

    Mehraeen, Shayan; Taşdemir, Adnan; Alkan Gürsel, Selmiye; Yürüm, Alp

    2018-06-01

    The pursuit of a promising replacement candidate for graphite as a Li-ion battery anode, which can satisfy both engineering criteria and market needs has been the target of researchers for more than two decades. In this work, we have investigated the synergistic effect of nitrogen-doped reduced graphene oxide (NrGO) and nanotubular TiO2 to achieve high rate capabilities with high discharge capacities through a simple, one-step and scalable method. First, nanotubes of hydrogen titanate were hydrothermally grown on the surface of NrGO sheets, and then converted to a mixed phase of TiO2-B and anatase (TB) by thermal annealing. Specific surface area, thermal gravimetric, structural and morphological characterizations were performed on the synthesized product. Electrochemical properties were investigated by cyclic voltammetry and cyclic charge/discharge tests. The prepared anode showed high discharge capacity of 150 mAh g‑1 at 1 C current rate after 50 cycles. The promising capacity of synthesized NrGO-TB was attributed to the unique and novel microstructure of NrGO-TB in which long nanotubes of TiO2 have been grown on the surface of NrGO sheets. Such architecture synergistically reduces the solid-state diffusion distance of Li+ and increases the electronic conductivity of the anode.

  8. Effective Removal of Congo Red by Triarrhena Biochar Loading with TiO2 Nanoparticles

    Directory of Open Access Journals (Sweden)

    Peng Yu

    2018-01-01

    Full Text Available A composite of pyrolytic Triarrhena biochar loading with TiO2 nanoparticles has been synthesized by the sol-gel method. The composite shows a well-developed hollow mesoporous and macropore structure as characterized by XRD, BET, and SEM. When used as an absorbent to remove Congo red from aqueous solution, it was found that as-prepared composite performed better absorption capacity than single biochar or TiO2. The results suggest that biochar loading with TiO2 could be promisingly implemented as an environmentally friendly and inexpensive adsorbent for Congo red removal from wastewater.

  9. Fabrication and characterization of mesoporous TiO2/polypyrrole-based nanocomposite for electrorheological fluid

    International Nuclear Information System (INIS)

    Wei Chuan; Zhu Yihua; Jin Yi; Yang Xiaoling; Li Chunzhong

    2008-01-01

    Mesoporous TiO 2 /polypyrrole (PPy)-based nanocomposite for electrorheological fluid was synthesized through one-pot method. By exploiting the combination conductivity of PPy and high dielectric constant of TiO 2 , the ER fluid exhibited an enhanced effect. The shear stress was 3.3 times as high as that of mesoporous TiO 2 . Powder X-ray diffraction (XRD), TEM and Fourier transform infrared (FT-IR) spectroscopy were employed to characterize the as-made samples. Using a modified rotational viscometer, the electrorheological effect was measured. Dielectric spectra were also given to explain the mechanism

  10. Enhanced photoelectrocatalytic performance for degradation of diclofenac and mechanism with TiO2 nano-particles decorated TiO2 nano-tubes arrays photoelectrode

    International Nuclear Information System (INIS)

    Cheng, Xiuwen; Liu, Huiling; Chen, Qinghua; Li, Junjing; Wang, Pu

    2013-01-01

    In this study, TiO 2 nano-particles decorated TiO 2 nano-tubes arrays (TiO 2 NPs/TiO 2 NTAs) photoelectrodes have been successfully prepared through anodization, combined with ultrasonic strategy, followed by annealing post-treatment. The morphology and structure of the as-prepared TiO 2 NPs/TiO 2 NTAs photoelectrodes were characterized by scanning electrons microscopy (SEM), N 2 adsorption/desorption isotherms, X-ray diffraction (XRD) and UV–visible light diffuse reflection spectroscopy (DRS). In addition, the generation of hydroxyl radicals (·OH) was detected by a photoluminescence (PL) spectra using terephthalic acid (TA) as a probe molecule. Furthermore, the photoelectrochemical (PECH) properties of TiO 2 NPs/TiO 2 NTAs photoanode were investigated through transient open circuit potential (OCP), photocurrent response (PCR) and electrochemical impedance spectroscopy (EIS). It was found that TiO 2 NPs/TiO 2 NTAs photoelectrode exhibited a distinct decrease of OCP of −0.219 mV cm −2 and PCR of 0.049 mA cm −2 , while a significantly enhanced photoelectrocatalytic (PEC) efficiency of 63.6% (0.4 V vs. SCE) for the degradation of diclofenac. Moreover, the enhanced PEC mechanism of TiO 2 NPs/TiO 2 NTAs photoanode was proposed. The high PEC performance could be attributed to the decoration of TiO 2 NPs, which could improve the mobility and separation efficiency of photoinduced charge carriers under external potential

  11. Molybdenum carbide-carbon nanocomposites synthesized from a reactive template for electrochemical hydrogen evolution

    KAUST Repository

    Alhajri, Nawal Saad

    2014-01-01

    Molybdenum carbide nanocrystals (Mo2C) with sizes ranging from 3 to 20 nm were synthesized within a carbon matrix starting from a mesoporous graphitic carbon nitride (mpg-C3N4) template with confined pores. A molybdenum carbide phase (Mo2C) with a hexagonal structure was formed using a novel synthetic method involving the reaction of a molybdenum precursor with the carbon residue originating from C3N4 under nitrogen at various temperatures. The synthesized nanocomposites were characterized using powder X-ray diffraction (XRD), temperature-programmed reaction with mass spectroscopy (MS), CHN elemental analyses, thermogravimetric analyses (TGA), nitrogen sorption, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The results indicated that the synthesized samples have different surface structures and compositions, which are accordingly expected to exhibit different electrocatalytic activities toward the hydrogen evolution reaction (HER). Electrochemical measurements demonstrated that the sample synthesized at 1323 K exhibited the highest and most stable HER current in acidic media, with an onset potential of -100 mV vs. RHE, among the samples prepared in this study. This result is attributed to the sufficiently small particle size (∼8 nm on average) and accordingly high surface area (308 m2 g-1), with less oxidized surface entrapped within the graphitized carbon matrix. © 2014 the Partner Organisations.

  12. Highly efficient indoor air purification using adsorption-enhanced-photocatalysis-based microporous TiO2 at short residence time.

    Science.gov (United States)

    Lv, Jinze; Zhu, Lizhong

    2013-01-01

    A short residence time is a key design parameter for the removal of organic pollutants in catalyst-based indoor air purification systems. In this study, we synthesized a series of TiO2 with different micropore volumes and studied their removal efficiency of indoor carbonyl pollutants at a short residence time. Our results indicated that the superior adsorption capability of TiO2 with micropores improved its performance in the photocatalytic degradation of cyclohexanone, while the photocatalytic removal of the pollutant successfully kept porous TiO2 from becoming saturated. When treated with 1 mg m(-3) cyclohexanone at a relatively humidity of 18%, the adsorption amount on microporous TiO2 was 5.4-7.9 times higher than that on P25. Removal efficiency via photocatalysis followed'the same order as the adsorption amount: TiO2-5 > TiO2-20 > TiO2-60 > TiO2-180 > P25. The advantage of microporous TiO2 over P25 became more pronounced when the residence time declined from 0.072 to 0.036 s. Moreover, as the concentration of cyclohexanone deceased from 1000 ppb to 500 ppb, removal efficiency by microporous TiO2 increased more rapidly than P25.

  13. Synthesis and characterization of TiO2/CdS core–shell nanorod arrays and their photoelectrochemical property

    International Nuclear Information System (INIS)

    Cao Chunlan; Hu Chenguo; Shen Weidong; Wang, Shuxia; Tian Yongshu; Wang Xue

    2012-01-01

    Highlights: ► TiO 2 /CdS core–shell nanorod arrays were fabricated by spin-SILAR method. ► The enhanced photocurrent was found in the TiO 2 /CdS core–shell nanorod arrays. ► The CdS coated on TiO 2 increases the e-h separation and enlarges light absorption range. - Abstract: TiO 2 /CdS core–shell nanorod arrays have been fabricated via a two-step method. Vertically aligned TiO 2 nanorod arrays (NRs) were synthesized by a facile hydrothermal method, and followed by depositing CdS nanoparticles on TiO 2 NRs by spin-coating successive ion layer adsorption and reaction (spin-SILAR) method. The surface morphology, structure, optical and photoelectrochemical behaviors of the core–shell NRs films are considered. The UV–vis absorption spectrum results suggested that the absorption peak of the TiO 2 /CdS core–shell NRs shifts from the ultraviolet region to the visible region in comparison to that of the pure TiO 2 NRs. The obviously enhanced photoelectrochemical (PEC) performances of the heterojunction NRs were found under illumination of the simulated sunlight in comparison with that of the TiO 2 NRs. The enhanced PEC performance and formation mechanism of TiO 2 /CdS core–shell NRs were discussed in detail.

  14. Nanostructured TiO2 microspheres for dye-sensitized solar cells employing a solid state polymer electrolyte

    International Nuclear Information System (INIS)

    Jung, Hun-Gi; Nagarajan, Srinivasan; Kang, Yong Soo; Sun, Yang-Kook

    2013-01-01

    Bimodal mesoporous, anatase TiO 2 microspheres with particle sizes ranging from 0.3 to 2 μm were synthesized using a facile solvothermal method. The photovoltaic performance of TiO 2 microspheres in dye-sensitized solar cells (DSSCs) using a solid state electrolyte was investigated. The solid state electrolyte DSSC device based on the TiO 2 microspheres exhibits an energy conversion efficiency of 4.2%, which is greater than that of commercial P25 TiO 2 (3.6%). The higher photocurrent density was primarily achieved as a result of the greater specific surface area and pore size, which resulted in an increase in the dye uptake of the TiO 2 microspheres and easy transport of solid electrolyte through mesopores. In addition, the greater electron lifetime and superior light scattering ability also enhanced the photovoltaic performance of the TiO 2 microsphere-based, solid state DSSCs

  15. Effect of hydrogen on the microstructure and electrochemical properties of Si nanoparticles synthesized by microwave plasma

    Energy Technology Data Exchange (ETDEWEB)

    Koo, Jeongboon; Lee, Jeongeun; Kim, Joonsoo; Jang, Boyun, E-mail: byjang@kier.re.kr

    2016-09-01

    We synthesized silicon (Si) nanoparticles using an atmospheric microwave plasma process, and investigated the effects of hydrogen (H{sub 2}) injection on their microstructure during the synthesis. Two nozzles were applied to inject H{sub 2} (swirling and rectilinear H{sub 2}). Our microstructural analysis indicated that the amount and method of H{sub 2} injection were critical for completion of the reaction from silicon tetrachloride (SiCl{sub 4}) to Si, as well as to obtain highly crystalline Si nanoparticles. The swirling H{sub 2} was especially critical due to its formation of vortex flow, which allowed relatively long residence time of the H-ions in plasma. The Si nanoparticles synthesized by the atmospheric plasma process had core-shell structures that consisted of crystalline Si cores with amorphous SiO{sub x} shells of 5–15 nm thickness. We also investigated the feasibility of the synthesized Si nanoparticles as anode materials in a lithium-ion battery (LIB). For the core-shell structured Si nanoparticles, we obtained the first reversible capacity of 1204 mAhg{sup −1}, and a capacity retention of 82.2% at the 50{sup th} cycle. - Highlights: • We synthesized Si nanoparticles by an atmospheric microwave plasma process. • We investigated the effects of injected H{sub 2} on the microstructures of Si nanoparticles. • Swirling H{sub 2} was critical, due to the formation of vortex flow in plasma. • The synthesized Si nanoparticles had core (crystalline Si)-shell (SiO{sub x}) structures. • The electrochemical properties depend on its core-shell structures as LIB anode.

  16. Structure and electrochemical hydrogen storage properties of Ti2Ni alloy synthesized by ball milling

    International Nuclear Information System (INIS)

    Hosni, B.; Li, X.; Khaldi, C.; ElKedim, O.; Lamloumi, J.

    2014-01-01

    Highlights: • The Ti 2 Ni alloy activation requires only one cycle of charge and discharge, regardless of the temperature. • By increasing the temperature the capacity loss, undergoes an increase and it is more pronounced for the 60 °C. • A good correlation is found between the evolutions of the different electrochemical parameters according to the temperature. - Abstract: The structure and the electrochemical hydrogen storage properties of amorphous Ti 2 Ni alloy synthesized by ball milling and used as an anode in nickel–metal hydride batteries were studied. Nominal Ti 2 Ni was synthesized under argon atmosphere at room temperature using a planetary high-energy ball mill. The structural and morphological characterization of the amorphous Ti 2 Ni alloy is carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical characterization of the Ti 2 Ni electrodes is carried out by the galvanostatic charging and discharging, the constant potential discharge, the open circuit potential and the potentiodynamic polarization techniques. The Ti 2 Ni alloy activation requires only one cycle of charge and discharge, regardless of the temperature. The electrochemical discharge capacity of the Ti 2 Ni alloy, during the first eight cycles, and at a temperature of 30 °C, remained practically unchanged and a good held cycling is observed. By increasing the temperature, the electrochemical discharge capacity loss after eight cycles undergoes an increase and it is more pronounced for the temperature 60 °C. At 30 °C, the anodic corrosion current density is 1 mA cm −2 and then it undergoes a rapid drop, remaining substantially constant (0.06 mA cm −2 ) in the range 40–60 °C, before undergoing a slight increase to 70 °C (0.3 mA cm −2 ). This variation is in good agreement with the maximum electrochemical discharge capacity values found for the different temperatures. By increasing the

  17. Synthesis and photocatalytic activity of Ce-doped TiO2 and TiO2 nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Arruda, L.B.; Pereira, E.A.; Paula, F.R.; Lisboa Filho, P.N. [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), SP (Brazil)

    2016-07-01

    Full text: One-dimensional nanostructures have been intensively studied, from the point of view of their synthesis and mechanisms of formation, as well as their applications in photonics, solar energy conversion, environmental and photocatalysis, since their properties due high surface area, electrical conductivity and light dispersion effects. Titanium dioxide (TiO2) nanoparticles have been demonstrated to be an effective multifunctional material especially when the particle size is less than 50 nm exhibit photoinduced activities that originate from the semiconductor band gap. TiO2 is semiconductor more used in photocatalysis, for this reason various properties have been thoroughly investigated in order to show that the photocatalytic activity and TiO2 reaction mechanism are influenced by structure, defects and impurities, surface morphology. and interfaces in addition to the concentration of dopants, such as rare-earth elements. Cerium ions, for example, vary between Ce4+ and Ce3 + oxidation state making the cerium oxide appear as CeO2 and Ce2O3 under oxidation and reduction conditions. These different electronic structures of Ce3+ (4f15d0) and Ce4+ (4f05d0) provide different catalytic and optical properties at the TiO2. In this work, samples of Ce-doped TiO2 and TiO2 were synthesized by alkali route, and its photocatalytic activity analyzed in order to create a relationship between the response obtained and the structure and morphology of each sample. Alkali route consists in submitting TiO2 (anatase) powder directly in medium of the NaOH (10M) and maintained at 120°C/20 hours by a glycerin bath with subsequent washed with water and HCl (0.1M) until reaching the desired pH. The synthesized samples were then studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The photocatalytic decomposition of rhodamine B (Rh.B) it was performed under UV irradiation and visible light in air. For the obtained

  18. Synthesis and photocatalytic activity of Ce-doped TiO2 and TiO2 nanotubes

    International Nuclear Information System (INIS)

    Arruda, L.B.; Pereira, E.A.; Paula, F.R.; Lisboa Filho, P.N.

    2016-01-01

    Full text: One-dimensional nanostructures have been intensively studied, from the point of view of their synthesis and mechanisms of formation, as well as their applications in photonics, solar energy conversion, environmental and photocatalysis, since their properties due high surface area, electrical conductivity and light dispersion effects. Titanium dioxide (TiO2) nanoparticles have been demonstrated to be an effective multifunctional material especially when the particle size is less than 50 nm exhibit photoinduced activities that originate from the semiconductor band gap. TiO2 is semiconductor more used in photocatalysis, for this reason various properties have been thoroughly investigated in order to show that the photocatalytic activity and TiO2 reaction mechanism are influenced by structure, defects and impurities, surface morphology. and interfaces in addition to the concentration of dopants, such as rare-earth elements. Cerium ions, for example, vary between Ce4+ and Ce3 + oxidation state making the cerium oxide appear as CeO2 and Ce2O3 under oxidation and reduction conditions. These different electronic structures of Ce3+ (4f15d0) and Ce4+ (4f05d0) provide different catalytic and optical properties at the TiO2. In this work, samples of Ce-doped TiO2 and TiO2 were synthesized by alkali route, and its photocatalytic activity analyzed in order to create a relationship between the response obtained and the structure and morphology of each sample. Alkali route consists in submitting TiO2 (anatase) powder directly in medium of the NaOH (10M) and maintained at 120°C/20 hours by a glycerin bath with subsequent washed with water and HCl (0.1M) until reaching the desired pH. The synthesized samples were then studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The photocatalytic decomposition of rhodamine B (Rh.B) it was performed under UV irradiation and visible light in air. For the obtained

  19. Facile approach to synthesize Ni(OH)2 nanoflakes on MWCNTs for high performance electrochemical supercapacitors

    International Nuclear Information System (INIS)

    Shahid, Muhammad; Liu Jingling; Shakir, Imran; Warsi, Muhammad Farooq; Nadeem, Muhammad; Kwon, Young-Uk

    2012-01-01

    Highlights: ► Deposition of ultra-thin Ni(OH) 2 nanoflakes on MWCNTs. ► Full utilization of the Ni(OH) 2 nanoflakes which provide maximum pseudocapacitance while minimizing the high surface area. ► The ultra-thin layer of Ni(OH) 2 nanoflakes on highly conductive MWCNTs is favorable for fast ion and electron transfer. ► The ultra-thin layer of Ni(OH) 2 nanoflakes on MWCNTs exhibited good cycling stability and lifetime. - Abstract: Ultrathin nanoflakes of Ni(OH) 2 were synthesized onto multi-walled carbon nanotubes (MWCNTs) by simple low cost chemically precipitation method for high performance electrochemical supercapacitor applications. The synthesized ultrathin Ni(OH) 2 exhibit high specific capacitance of 1735 Fg −1 at a scan rate of 5 mV s −1 with excellent rate capability. This high performance of Ni(OH) 2 nanoflakes was attributed to its complete accessibility to the electrolyte and maximum utilization of metal hydroxides. Findings of this work suggest that synthesized electrodes offer low-cost and scalable solution for high-performance energy storage devices.

  20. Light-induced antifungal activity of TiO2 nanoparticles/ZnO nanowires

    International Nuclear Information System (INIS)

    Haghighi, N.; Abdi, Y.; Haghighi, F.

    2011-01-01

    Antifungal activity of TiO 2 /ZnO nanostructures under visible light irradiation was investigated. A simple chemical method was used to synthesize ZnO nanowires. Zinc acetate dihydrate, Polyvinyl Pyrrolidone and deionized water were used as precursor, capping and solvent, respectively. TiO 2 nanoparticles were deposited on ZnO nanowires using an atmospheric pressure chemical vapor deposition system. X-ray diffraction pattern of TiO 2 /ZnO nano-composite has represented the diffraction peaks relating to the crystal planes of the TiO 2 (anatase and rutile) and ZnO. TiO 2 /ZnO nanostructure antifungal effect on Candida albicans biofilms was studied and compared with the activity of TiO 2 nanoparticles and ZnO nanowires. The high efficiency photocatalytic activity of TiO 2 nanoparticles leads to increased antifungal activity of ZnO nanowires. Scanning electron microscope was utilized to study the morphology of the as prepared nanostructures and the degradation of the yeast.

  1. Photocatalytic degradation of Rhodamine B dye using Fe doped TiO2 nanocomposites

    Science.gov (United States)

    Barkhade, Tejal; Banerjee, Indrani

    2018-05-01

    The unique properties of titanium dioxide (TiO2) such as high photo catalytic activity, high chemical stability and low toxicity have made it a suitable photocatalyst in recent decades. The effect of modification of TiO2 with doping of iron on its characteristics and photo catalytic efficiency was studied. The change in band gap energy of TiO2 nanoparticles after doping with Fe has been studied. Significant enhancement in photo catalytic property of TiO2 after Fe doping under light exposure conditions has been investigated. Acute exposure to non-biodegradable Rhodamine B resulted in many health problems like burning of eyes, skin irritation, nasal burning, and chest pain etc. Therefore, degradation of this dye is needed to save environment and animals. Considering the similar radius of Fe3+ and Ti4+ ions (respectively 0.64 Å and 0.68 Å), titanium position in the lattice of TiO2 can be replaced by iron cations easily. The undoped and Fe doped TiO2 nano composites were synthesized by sol-gel method, in which 1.0M% of Fe was doped with TiO2 and then the samples were characterized by using FE-SEM, UV-Visible diffuse spectroscopy, Raman Spectroscopy, and FTIR. Photo catalytic degradation of Rhodamine B dye experiment was carried out in visible light range. After 90 min time duration pink colour of dye turned colourless, indicating significant degradation rate with time.

  2. Photocatalytic oxidative desulfurization of dibenzothiophene catalyzed by amorphous TiO2 in ionic liquid

    International Nuclear Information System (INIS)

    Zhu, Wenshuai; Xu, Yehai; Li, Huaming; Dai, Bilian; Xu, Hui; Wang, Chao; Chao, Yanhong; Liu, Hui

    2014-01-01

    Three types of TiO 2 were synthesized by a hydrolysis and calcination method. The catalysts were characterized by X-ray powder diffraction (XRD), diffuse reflectance spectrum (DRS), Raman spectra, and X-ray photoelectron spectroscopy (XPS). The XRD and Raman spectra indicated that amorphous TiO 2 was successfully obtained at 100 .deg. C. The results indicated that amorphous TiO 2 achieved the highest efficiency of desulfurization. The photocatalytic oxidation of dibenzothiophene (DBT), benzothiophene (BT), 4,6-dimethyldibenzothiophene (4,6-DMDBT) and dodecanethiol (RSH) in model oil was studied at room temperature (30 .deg. C) with three catalysts. The system contained amorphous TiO 2 , H 2 O 2 , and [Bmim]BF 4 ionic liquid, ultraviolet (UV), which played vitally important roles in the photocatalytic oxidative desulfurization. Especially, the molar ratio of H 2 O 2 and sulfur (O/S) was only 2 : 1, which corresponded to the stoichiometric reaction. The sulfur removal of DBT-containing model oil with amorphous TiO 2 could reach 96.6%, which was apparently superior to a system with anatase TiO 2 (23.6%) or with anatase - rutile TiO 2 (18.2%). The system could be recycled seven times without a signicant decrease in photocatalytic activity

  3. Probing Photocatalytic Characteristics of Sb-Doped TiO2 under Visible Light Irradiation

    Directory of Open Access Journals (Sweden)

    Lingjing Luo

    2014-01-01

    Full Text Available Sb-doped TiO2 nanoparticle with varied dopant concentrations was synthesized using titanium tetrachloride (TiCl4 and antimony chloride (SbCl3 as the precursors. The properties of Sb-doped TiO2 nanoparticles were characterized by X-ray diffraction (XRD, scanning electron microscope (SEM, fluorescence spectrophotometer, and Uv-vis spectrophotometer. The absorption edge of TiO2 nanoparticles could be extended to visible region after doping with antimony, in contrast to the UV absorption of pure TiO2. The results showed that the photocatalytic activity of Sb-doped TiO2 nanoparticles was much more active than pure TiO2. The 0.1% Sb-doped TiO2 nanoparticles demonstrated the best photocatalytic activity which was better than that of the Degussa P25 under visible light irradiation using terephthalic acid as fluorescent probe. The effects of Sb dopant on the photocatalytic activity and the involved mechanism were extensively investigated in this work as well.

  4. Pt Catalyst Supported within TiO2 Mesoporous Films for Oxygen Reduction Reaction

    International Nuclear Information System (INIS)

    Huang, Dekang; Zhang, Bingyan; Bai, Jie; Zhang, Yibo; Wittstock, Gunther; Wang, Mingkui; Shen, Yan

    2014-01-01

    In this study, dispersed Pt nanoparticles into mesoporous TiO 2 thin films are fabricated by a facile electrochemical deposition method as electro-catalysts for oxygen reduction reaction. The mesoporous TiO 2 thin films coated on the fluorine-doped tin oxide glass by screen printing allow a facile transport of reactants and products. The structural properties of the resulted Pt/TiO 2 electrode are evaluated by field emission scanning electron microscopy, energy dispersive X-ray spectrometry, X-ray diffraction, and X-ray photoelectron spectroscopy. Cyclic voltammetry measurements are performed to study the electrochemical properties of the Pt/TiO 2 electrode. Further study demonstrates the stability of the Pt catalyst supported within TiO 2 mesoporous films for the oxygen reduction reaction

  5. Electrochemical Study on Newly Synthesized Chlorocurcumin as an Inhibitor for Mild Steel Corrosion in Hydrochloric Acid

    Directory of Open Access Journals (Sweden)

    Ahmed A. Al-Amiery

    2013-11-01

    Full Text Available A new curcumin derivative, i.e., (1E,4Z,6E-5-chloro-1,7-bis(4-hydroxy-3-methoxyphenylhepta-1,4,6-trien-3-one (chlorocurcumin, was prepared starting with the natural compound curcumin. The newly synthesized compound was characterized by elemental analysis and spectral studies (IR, 1H-NMR and 13C-NMR. The corrosion inhibition of mild steel in 1 M HCl by chlorocurcumin has been studied using potentiodynamic polarization (PDP measurements and electrochemical impedance spectroscopy (EIS. The inhibition efficiency increases with the concentration of the inhibitor but decreases with increases in temperature. The potentiodynamic polarization reveals that chlorocurcumin is a mixed-type inhibitor. The kinetic parameters for mild steel corrosion were determined and discussed.

  6. Morphological, structural and electrochemical properties of lithium iron phosphates synthesized by Spray Pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Gomez, L.S. [Universidad Carlos III de Madrid and IAAB, Avda. de la Universidad, 30, 28911 Leganes, Madrid (Spain); Meatza, I. de [Dpto. Energia, CIDETEC, Po Miramon 196, Parque Tecnologico de San Sebastian, 20009 Donostia-San Sebastian (Spain); Martin, M.I., E-mail: imartin@ietcc.csic.e [Universidad Carlos III de Madrid and IAAB, Avda. de la Universidad, 30, 28911 Leganes, Madrid (Spain); Bengoechea, M. [Dpto. Energia, CIDETEC, Po Miramon 196, Parque Tecnologico de San Sebastian, 20009 Donostia-San Sebastian (Spain); Cantero, I. [Dpto. I-D-i Nuevas Tecnologias, CEGASA, Artapadura, 11, 01013 Vitoria-Gasteiz (Spain); Rabanal, M.E., E-mail: mariaeugenia.rabanal@uc3m.e [Universidad Carlos III de Madrid and IAAB, Avda. de la Universidad, 30, 28911 Leganes, Madrid (Spain)

    2010-03-01

    In the field of materials for lithium ion batteries, the lithium iron phosphate LiFePO{sub 4} has been proven for use as a positive electrode due to its good resistance to thermal degradation and overcharge, safety and low cost. The use of nanostructured materials would improve its efficiency. This work shows the results of the synthesis of nanostructured materials with functional properties for lithium batteries through aerosol techniques. The Spray Pyrolysis method allows synthesizing nanostructured particles with spherical geometry, not agglomerates, with narrow distribution of particle size and homogeneous composition in respect to a precursor solution. Experimental techniques were focused on the morphological (SEM and TEM), structural (XRD and HRTEM-SAED), chemical (EDS) and electrochemical characterization.

  7. Electrochemical Study on Newly Synthesized Chlorocurcumin as an Inhibitor for Mild Steel Corrosion in Hydrochloric Acid

    Science.gov (United States)

    Al-Amiery, Ahmed A.; Kadhum, Abdul Amir H.; Mohamad, Abu Bakar; Musa, Ahmed Y.; Li, Cheong Jiun

    2013-01-01

    A new curcumin derivative, i.e., (1E,4Z,6E)-5-chloro-1,7-bis(4-hydroxy-3-methoxyphenyl)hepta-1,4,6-trien-3-one (chlorocurcumin), was prepared starting with the natural compound curcumin. The newly synthesized compound was characterized by elemental analysis and spectral studies (IR, 1H-NMR and 13C-NMR). The corrosion inhibition of mild steel in 1 M HCl by chlorocurcumin has been studied using potentiodynamic polarization (PDP) measurements and electrochemical impedance spectroscopy (EIS). The inhibition efficiency increases with the concentration of the inhibitor but decreases with increases in temperature. The potentiodynamic polarization reveals that chlorocurcumin is a mixed-type inhibitor. The kinetic parameters for mild steel corrosion were determined and discussed. PMID:28788402

  8. Morphological, structural and electrochemical properties of lithium iron phosphates synthesized by Spray Pyrolysis

    International Nuclear Information System (INIS)

    Gomez, L.S.; Meatza, I. de; Martin, M.I.; Bengoechea, M.; Cantero, I.; Rabanal, M.E.

    2010-01-01

    In the field of materials for lithium ion batteries, the lithium iron phosphate LiFePO 4 has been proven for use as a positive electrode due to its good resistance to thermal degradation and overcharge, safety and low cost. The use of nanostructured materials would improve its efficiency. This work shows the results of the synthesis of nanostructured materials with functional properties for lithium batteries through aerosol techniques. The Spray Pyrolysis method allows synthesizing nanostructured particles with spherical geometry, not agglomerates, with narrow distribution of particle size and homogeneous composition in respect to a precursor solution. Experimental techniques were focused on the morphological (SEM and TEM), structural (XRD and HRTEM-SAED), chemical (EDS) and electrochemical characterization.

  9. Flexible supercapacitor based on electrochemically synthesized pyrrole formyl pyrrole copolymer coated on carbon microfibers

    International Nuclear Information System (INIS)

    Gholami, Mehrdad; Moozarm Nia, Pooria; Narimani, Leila; Sokhakian, Mehran; Alias, Yatimah

    2016-01-01

    Highlights: • A Flexible supercapacitor prepared by carbon microfibers coated with P(Py-co-FPy). • The variation of capacitance with different mole ratio of monomers is investigated. • The capacitance measured by different electrochemical methods. • This flexible supercapacitor can be discharged in higher currents for longer time. - Abstract: The main objective of this work is to prepare a flexible supercapacitor using electrochemically synthesized pyrrole formyl pyrrole copolymer P(Py-co-FPy) coated on the carbon microfibers. Due to difficulties of working with carbon microfibers, glassy carbon was used to find out optimized conditions by varying mole ratio of pyrrole and formyl pyrrole monomers on the capacitance value. The prepared electrodes were characterized using Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscope (FESEM), Brunauer–Emmett–Teller (BET) analysis, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Then the X-ray photoelectron spectroscopy (XPS) was used to characterize the optimized electrode. The specific capacitance is calculated using cyclic voltammetry, charge/discharge method, and impedance spectroscopy. The charge/discharge study reveals that the best specific capacitance is estimated to be 220.3 mF cm"−"2 for equal mole fraction of pyrrole and formyl pyrrole Py (0.1)-FP (0.1) at discharge current of 3 × 10"−"4 A. This optimized electrode keeps about 92% of its capacitance value in high current of discharging. The specific capacitances calculated by all the mentioned methods are in agreement with each other. Finally, the found optimized conditions were successfully applied to produce a flexible supercapacitor on the surface of carbon microfibers.

  10. Flexible supercapacitor based on electrochemically synthesized pyrrole formyl pyrrole copolymer coated on carbon microfibers

    Energy Technology Data Exchange (ETDEWEB)

    Gholami, Mehrdad, E-mail: mehrdad897@um.edu.my [University of Malaya center for ionic liquids, Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Department of Chemistry, Marvdasht Branch, Islamic Azad University, P.O. Box 465, Marvdasht (Iran, Islamic Republic of); Moozarm Nia, Pooria, E-mail: pooriamn@yahoo.com [University of Malaya center for ionic liquids, Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Narimani, Leila, E-mail: Narimani.leila@gmail.com [University of Malaya center for ionic liquids, Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Sokhakian, Mehran, E-mail: m.sokhakian@gmail.com [University of Malaya center for ionic liquids, Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Alias, Yatimah, E-mail: yatimah70@um.edu.my [University of Malaya center for ionic liquids, Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2016-08-15

    Highlights: • A Flexible supercapacitor prepared by carbon microfibers coated with P(Py-co-FPy). • The variation of capacitance with different mole ratio of monomers is investigated. • The capacitance measured by different electrochemical methods. • This flexible supercapacitor can be discharged in higher currents for longer time. - Abstract: The main objective of this work is to prepare a flexible supercapacitor using electrochemically synthesized pyrrole formyl pyrrole copolymer P(Py-co-FPy) coated on the carbon microfibers. Due to difficulties of working with carbon microfibers, glassy carbon was used to find out optimized conditions by varying mole ratio of pyrrole and formyl pyrrole monomers on the capacitance value. The prepared electrodes were characterized using Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscope (FESEM), Brunauer–Emmett–Teller (BET) analysis, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Then the X-ray photoelectron spectroscopy (XPS) was used to characterize the optimized electrode. The specific capacitance is calculated using cyclic voltammetry, charge/discharge method, and impedance spectroscopy. The charge/discharge study reveals that the best specific capacitance is estimated to be 220.3 mF cm{sup −2} for equal mole fraction of pyrrole and formyl pyrrole Py (0.1)-FP (0.1) at discharge current of 3 × 10{sup −4} A. This optimized electrode keeps about 92% of its capacitance value in high current of discharging. The specific capacitances calculated by all the mentioned methods are in agreement with each other. Finally, the found optimized conditions were successfully applied to produce a flexible supercapacitor on the surface of carbon microfibers.

  11. Electrochemical Capacitors Based on Aligned Carbon Nanotubes Directly Synthesized on Tantalum Substrates

    International Nuclear Information System (INIS)

    Kim, Byung Woo; Chung, Hae Geun; Kim, Woong; Min, Byoung Koun; Kim, Hong Gon

    2010-01-01

    We demonstrate that vertically aligned carbon nanotubes can be synthesized directly on tantalum substrate via waterassisted chemical vapor deposition and evaluate their properties as electrochemical capacitors. The mean diameter of the carbon nanotubes was 7.1 ± 1.5 nm, and 70% of them had double walls. The intensity ratio of G-band to D-band in Raman spectra was as high as 5, indicating good quality of the carbon nanotubes. Owing to the alignment and low equivalent series resistance, the carbon nanotube based supercapacitors showed good rate performance. Rectangular shape of cyclic voltammogram was maintained even at the scan rate of > 1 V/s in 1 M sulfuric acid aqueous solution. Specific capacitance was well-retained (∼94%) even when the discharging current density dramatically increased up to 145 A/g. Consequently, specific power as high as 60 kW/kg was obtained from as-grown carbon nanotubes in aqueous solution. Maximum specific energy of ∼20 Wh/kg was obtained when carbon nanotubes were electrochemically oxidized and operated in organic solution. Demonstration of direct synthesis of carbon nanotubes on tantalum current collectors and their applications as supercapacitors could be an invaluable basis for fabrication of high performance carbon nanotube supercapacitors

  12. The influence of monomer concentration on the optical properties of electrochemically synthesized polypyrrole thin films

    International Nuclear Information System (INIS)

    Thombare, J. V.; Fulari, V. J.; Rath, M. C.; Han, S. H.

    2013-01-01

    Polypyrrole (PPy) thin films were deposited on stainless steel and ITO coated glass substrate at a constant deposition potential of 0.8 V versus saturated calomel electrode (SCE) by using the electrochemical polymerization method. The PPy thin films were deposited at room temperature at various monomer concentrations ranging from 0.1 M to 0.3 M pyrrole. The structural and optical properties of the polypyrrole thin films were investigated using an X-ray diffractometer (XRD), FTIR spectroscopy, scanning electron microscopy (SEM), and ultraviolet—visible (UV—vis) spectroscopy. The XRD results show that polypyrrole thin films have a semi crystalline structure. Higher monomer concentration results in a slight increase of crystallinity. The polypyrrole thin films deposited at higher monomer concentration exhibit high visible absorbance. The refractive indexes of the polypyrrole thin films are found to be in the range of 1 to 1.3 and vary with monomer concentration as well as wavelength. The extinction coefficient decreases slightly with monomer concentration. The electrochemically synthesized polypyrrole thin film shows optical band gap energy of 2.14 eV. (semiconductor materials)

  13. Cytotoxicity and antiviral activity of electrochemical - synthesized silver nanoparticles against poliovirus.

    Science.gov (United States)

    Huy, Tran Quang; Hien Thanh, Nguyen Thi; Thuy, Nguyen Thanh; Chung, Pham Van; Hung, Pham Ngoc; Le, Anh-Tuan; Hong Hanh, Nguyen Thi

    2017-03-01

    Silver nanoparticles (AgNPs) have been proven to have noticeable cytotoxicity in vitro and antiviral activity against some types of enveloped viruses. This paper presents the cytotoxicity and antiviral activity of pure AgNPs synthesized by the electrochemical method, towards cell culture and poliovirus (a non-enveloped virus). Prepared AgNPs were characterized by ultraviolet-visible spectroscopy, energy-dispersive X-ray spectroscopy and transmission electron microscopy. Before incubation with poliovirus, different concentrations of AgNPs were added to human rhabdomyosarcoma (RD) cell monolayers seeded in 96 well plates for testing their cytotoxicity. The in vitro cytotoxicity and anti-poliovirus activity of AgNPs were daily assessed for cytopathic effect (CPE) through inverted light microscopy. CPE in the tested wells was determined in comparison with those in wells of negative and positive control. Structure analysis showed that AgNPs were formed with a quasi-spherical shape with mean size about 7.1nm and high purity. No CPE of RD cells was seen in wells at the time point of 48h post-incubation with AgNPs at concentration up to 100ppm. The anti-poliovirus activity of AgNPs was determined at 3.13ppm corresponding to the viral concentration of 1TCID 50 (Tissue Culture Infective Dose) after 30min, and 10TCID 50 after 60min, the cell viability was found up to 98% at 48h post-infection, with no CPE found. Whereas, a strong CPE of RD cells was found at 48h post-infection with the mixture of AgNPs and poliovirus at concentration of 100TCID 50 , and in wells of positive controls. With mentioned advantages, electrochemical-synthesized AgNPs are promising candidate for advanced biomedical and disinfection applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Rutile TiO2 nanorod arrays directly grown on Ti foil substrates towards lithium-ion micro-batteries

    International Nuclear Information System (INIS)

    Dong Shanmu; Wang Haibo; Gu Lin; Zhou Xinhong; Liu Zhihong; Han Pengxian; Wang Ya; Chen Xiao; Cui Guanglei; Chen Liquan

    2011-01-01

    Nanosized rutile TiO 2 is one of the most promising candidates for anode material in lithium-ion micro-batteries owing to their smaller dimension in ab-plane resulting in an enhanced performance for area capacity. However, few reports have yet emerged up to date of rutile TiO 2 nanorod arrays growing along c-axis for Li-ion battery electrode application. In this study, single-crystalline rutile TiO 2 nanorod arrays growing directly on Ti foil substrates have been fabricated using a template-free method. These nanorods can significantly improve the electrochemical performance of rutile TiO 2 in Li-ion batteries. The capacity increase is about 10 times in comparison with rutile TiO 2 compact layer.

  15. TiO2 coated SnO2 nanosheet films for dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Cai Fengshi; Yuan Zhihao; Duan Yueqing; Bie Lijian

    2011-01-01

    TiO 2 -coated SnO 2 nanosheet (TiO 2 -SnO 2 NS) films about 300 nm in thickness were fabricated on fluorine-doped tin oxide glass by a two-step process with facile solution-grown approach and subsequent hydrolysis of TiCl 4 aqueous solution. The as-prepared TiO 2 -SnO 2 NSs were characterized by scanning electron microscopy and X-ray diffraction. The performances of the dye-sensitized solar cells (DSCs) with TiO 2 -SnO 2 NSs were analyzed by current-voltage measurements and electrochemical impedance spectroscopy. Experimental results show that the introduction of TiO 2 -SnO 2 NSs can provide an efficient electron transition channel along the SnO 2 nanosheets, increase the short current density, and finally improve the conversion efficiency for the DSCs from 4.52 to 5.71%.

  16. Photoelectrolysis of water using heterostructural composite of TiO2 nanotubes and nanoparticles

    International Nuclear Information System (INIS)

    Das, Prajna P; Mohapatra, Susanta K; Misra, Mano

    2008-01-01

    Efficient photoelectrolysis of water to generate hydrogen (H 2 ) can be carried out by designing photocatalysts with good absorption as well as charge transport properties. One dimensional (1D), self-organized titania (TiO 2 ) nanotubes are known to have excellent charge transport properties and TiO 2 nanoparticles (NPs) are good for better photon absorption. This paper describes the synthesis of a composite photocatalyst combining the above two properties of TiO 2 nanocomposites with different morphologies. TiO 2 NPs (5-9 nm nanocrystals form 500-700 nm clusters) have been synthesized from TiCl 4 precursor on TiO 2 nanotubular arrays (∼80 nm diameter and ∼550 nm length) synthesized by the sonoelectrochemical anodization method. This TiO 2 nanotube-nanoparticle composite photoanode has enabled obtaining of enhanced photocurrent density (2.2 mA cm -2 ) as compared with NTs (0.9 mA cm -2 ) and NPs (0.65 mA cm -2 ) alone.

  17. Adsorption and Recovery of Polyphenolic Flavonoids Using TiO_2-Functionalized Mesoporous Silica Nanoparticles

    International Nuclear Information System (INIS)

    Khan, M. Arif; Wallace, William T.; Islam, Syed Z.; Nagpure, Suraj; Strzalka, Joseph

    2017-01-01

    Exploiting specific interactions with titania (TiO_2) has been proposed for the separation and recovery of a broad range of biomolecules and natural products, including therapeutic polyphenolic flavonoids which are susceptible to degradation, such as quercetin. Functionalizing mesoporous silica with TiO_2 has many potential advantages over bulk and mesoporous TiO_2 as an adsorbent for natural products, including robust synthetic approaches leading to high surface area, stable separation platforms. Here, TiO_2 surface functionalized mesoporous silica nanoparticles (MSNPs) are synthesized and characterized as a function of TiO_2 content (up to 636 mg TiO2/g). The adsorption isotherms of two polyphenolic flavonoids, quercetin and rutin, were determined (0.05-10 mg/ml in ethanol), and a 100-fold increase in the adsorption capacity was observed relative to functionalized nonporous particles with similar TiO_2 surface coverage. An optimum extent of functionalization (approximately 440 mg TiO_2/g particles) is interpreted from characterization techniques including grazing incidence x-ray scattering (GIXS), high resolution transmission electron microscopy (HRTEM) and nitrogen adsorption, which examined the interplay between the extent of TiO_2 functionalization and the accessibility of the porous structures. The recovery of flavonoids is demonstrated using ligand displacement in ethanolic citric acid solution (20% w/v), in which greater than 90% recovery can be achieved in a multistep extraction process. The radical scavenging activity (RSA) of the recovered and particle-bound quercetin as measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay demonstrates greater than 80% retention of antioxidant activity by both particle-bound and recovered quercetin. In conclusion, these mesoporous titanosilicate materials can serve as a synthetic platform to isolate, recover, and potentially deliver degradation-sensitive natural products to biological systems.

  18. TiO2/Cu2O composite based on TiO2 NTPC photoanode for photoelectrochemical (PEC) water splitting under visible light

    KAUST Repository

    Shi, Le

    2015-05-01

    Water splitting through photoelectrochemical reaction is widely regarded as a major method to generate H2 , a promising source of renewable energy to deal with the energy crisis faced up to human being. Efficient exploitation of visible light in practice of water splitting with pure TiO2 material, one of the most popular semiconductor material used for photoelectrochemical water splitting, is still challenging. One dimensional TiO2 nanotubes is highly desired with its less recombination with the short distance for charge carrier diffusion and light-scattering properties. This work is based on TiO2 NTPC electrode by the optimized two-step anodization method from our group. A highly crystalized p-type Cu2O layer was deposited by optimized pulse potentiostatic electrochemical deposition onto TiO2 nanotubes to enhance the visible light absorption of a pure p-type TiO2 substrate and to build a p-n junction at the interface to improve the PEC performance. However, because of the real photocurrent of Cu2O is far away from its theoretical limit and also poor stability in the aqueous environment, a design of rGO medium layer was added between TiO2 nanotube and Cu2O layer to enhance the photogenerated electrons and holes separation, extend charge carrier diffusion length (in comparison with those of conventional pure TiO2 or Cu2O materials) which could significantly increase photocurrent to 0.65 mA/cm2 under visible light illumination (>420 nm) and also largely improve the stability of Cu2O layer, finally lead to an enhancement of water splitting performance.

  19. Synthesis of nanocomposite coating based on TiO2/ZnAl layer double hydroxides

    International Nuclear Information System (INIS)

    Jovanov, V.; Rudic, O.; Ranogajec, J.; Fidanchevska, E.

    2017-01-01

    The aim of this investigation was the synthesis of nanocomposite coatings based on Zn-Al layered double hydroxides (Zn-Al LDH) and TiO2. The Zn-Al LDH material, which acted as the catalyst support of the active TiO2 component (in the content of 3 and 10 wt. %), was synthesized by a low super saturation co-precipitation method. The interaction between the Zn-Al LDH and the active TiO2 component was accomplished by using vacuum evaporation prior to the mechanical activation and only by mechanical activation. The final suspension based on Zn-Al LDH and 10wt. % TiO2, impregnated only by mechanical activation, showed the optimal characteristics from the aspect of particle size distribution and XRD analysis. These properties had a positive effect on the functional properties of the coatings (photocatalytic activity and self-cleaning efficiency) after the water rinsing procedure. [es

  20. Synthesis of highly ordered TiO2 nanotube in malonic acid solution by anodization.

    Science.gov (United States)

    Ryu, Won Hee; Park, Chan Jin; Kwon, Hyuk Sang

    2008-10-01

    We synthesized TiO2 nanotube array by anodizing in a solution of malonic acid (HOOCCH2COOH) and NH4F, and analyzed the morphology of the nanotube using scanning electron microscopy (SEM). The morphology of TiO2 nanotube was largely affected by anodizing time, anodizing voltage, and malonic acid concentration. With increasing the anodizing voltage from 5 V to 20 V, the diameter of TiO2 nanotube was increased from about 20 nm to 110 nm and its length from about 10 nm to 700 nm. In addition, the length of TiO2 nanotube was increased with increasing anodizing time up to 6 h at 20 V. We obtained the longest and the most highly ordered nanotube structure when anodizing Ti in a solution of 0.5 wt% NH4F and 1 M malonic acid at 20 V for 6 h.

  1. Studies on Nano-Engineered TiO2 Photo Catalyst for Effective Degradation of Dye

    Science.gov (United States)

    Sowmya, S. R.; Madhu, G. M.; Hashir, Mohammed

    2018-02-01

    All Heterogeneous photo catalysis employing efficient photo-catalyst is the advanced dye degradation technology for the purification of textile effluent. The present work focuses on Congo red dye degradation employing synthesized Ag doped TiO2 nanoparticles as photocatalyst which is characterized using SEM, XRD and FTIR. Studies are conducted to study the effect of various parameters such as initial dye concentration, catalyst loading and pH of solution. Ag Doped TiO2 photocatalyst improve the efficacy of TiO2 by reducing high band gap and electron hole recombination of TiO2. The reaction kinetics is analyzed and the process is found to follow pseudo first order kinetics.

  2. DNA mediated wire-like clusters of self-assembled TiO2 nanomaterials: supercapacitor and dye sensitized solar cell applications

    Science.gov (United States)

    Nithiyanantham, U.; Ramadoss, Ananthakumar; Ede, Sivasankara Rao; Kundu, Subrata

    2014-06-01

    A new route for the formation of wire-like clusters of TiO2 nanomaterials self-assembled in DNA scaffold within an hour of reaction time is reported. TiO2 nanomaterials are synthesized by the reaction of titanium-isopropoxide with ethanol and water in the presence of DNA under continuous stirring and heating at 60 °C. The individual size of the TiO2 NPs self-assembled in DNA and the diameter of the wires can be tuned by controlling the DNA to Ti-salt molar ratios and other reaction parameters. The eventual diameter of the individual particles varies between 15 +/- 5 nm ranges, whereas the length of the nanowires varies in the 2-3 μm range. The synthesized wire-like DNA-TiO2 nanomaterials are excellent materials for electrochemical supercapacitor and DSSC applications. From the electrochemical supercapacitor experiment, it was found that the TiO2 nanomaterials showed different specific capacitance (Cs) values for the various nanowires, and the order of Cs values are as follows: wire-like clusters (small size) > wire-like clusters (large size). The highest Cs of 2.69 F g-1 was observed for TiO2 having wire-like structure with small sizes. The study of the long term cycling stability of wire-like clusters (small size) electrode were shown to be stable, retaining ca. 80% of the initial specific capacitance, even after 5000 cycles. The potentiality of the DNA-TiO2 nanomaterials was also tested in photo-voltaic applications and the observed efficiency was found higher in the case of wire-like TiO2 nanostructures with larger sizes compared to smaller sizes. In future, the described method can be extended for the synthesis of other oxide based materials on DNA scaffold and can be further used in other applications like sensors, Li-ion battery materials or treatment for environmental waste water.A new route for the formation of wire-like clusters of TiO2 nanomaterials self-assembled in DNA scaffold within an hour of reaction time is reported. TiO2 nanomaterials are

  3. Charge transfer in photorechargeable composite films of TiO2 and polyaniline

    Science.gov (United States)

    Nomiyama, Teruaki; Sasabe, Kenichi; Sakamoto, Kenta; Horie, Yuji

    2015-07-01

    A photorechargeable battery (PRB) is a photovoltaic device having an energy storage function in a single cell. The photoactive electrode of PRB is a bilayer film consisting of bare porous TiO2 and a TiO2-polyaniline (PANi) mixture that work as a photovoltaic current generator and an electrochemical energy storage by ion dedoping, respectively. To study the charge transfer between TiO2 and PANi, the photorechargeable quantum efficiency QE ([electron count on discharge]/[incident photon count on photocharge]) was measured by varying the thickness LS of the TiO2-PANi mixture. The quantum efficiency QEuv for UV photons had a maximum of ˜7% at LS ˜ 7 µm. The time constant τTP for the charge transfer was about 10-1 s, which was longer ten times or more than the lifetime of excited electrons within TiO2. These facts reveal that the main rate-limiting factor in the photocharging process is the charge transfer between TiO2 and PANi.

  4. Ultra-fine structural characterization and bioactivity evaluation of TiO2 nanotube layers.

    Science.gov (United States)

    Jang, JaeMyung; Kwon, TaeYub; Kim, KyoHan

    2008-10-01

    For an application as biomedical materials of high performance with a good biocompatibility, the TiO2 nanotube-type oxide film on Ti substrate has been fabricated by electrochemical method, and the effects of surface characteristics of TiO2 naotube layer have been investigated. The surface morphology of TiO2 nanotube layer depends on factors such as anodizing time, current density, and electrolyte temperature. Moreover, the cell and pore size gradually were increased with the passage of anodizing time. X-ray diffraction (XRD) results indicated that the TiO2 nanotube layer formed in acidic electrolytes was mainly composed of anatase structure containing rutile. From the analysis of chemical states of TiO2 nanotube layer using X-ray photoelectron spectroscopy (XPS), Ti2p, P2p and O1s were observed in the nanotubes layer, which were penetrated from the electrolyte into the oxide layer during anodic process. The incorporated phosphate species were found mostly in the forms of HPO4-, PO4-, and PO3-. From the result of biological evaluation in simulated body fluid (SBF) the TiO2 nanotube layer was effective for bioactive property.

  5. Facile synthesis of improved room temperature gas sensing properties of TiO2 nanostructures: Effect of acid treatment

    CSIR Research Space (South Africa)

    Tshabalala, Zamaswazi P

    2016-03-01

    Full Text Available TiO2 nanoparticles were synthesized via a simple hydrothermal method in a sodium hydroxide (NaOH) aqueous solution and washed with distilled water and different concentrations of hydrochloric acid which acted as the morphological...

  6. Synergy between TiO2 and CoxOy sites in electrocatalytic water decomposition

    NARCIS (Netherlands)

    Szyja, B.M.; van Santen, R.A.

    2015-01-01

    A computational study of the cooperative effect of a small four-atom Co oxide cluster supported on the TiO2 anatase (100) surface in the electrochemical water splitting reaction is presented. The results have been obtained including explicit solvent water molecules by means of Car-Parrinello MD

  7. A new approach of tailoring wetting properties of TiO2 nanotubular surfaces

    KAUST Repository

    Isimjan, Tayirjan T.; Yan, Zhu; Yang, D. Q.; Rohani, Sohrab M F; Ray, Ajay

    2012-01-01

    TiO2 nanotube layers were grown on a Ti surface by electrochemical anodization. As prepared, these layers showed a superhydrophilic wetting behavior. Modified with 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane (PTES), the layers showed a

  8. Comparing the photocatalytic activity of TiO2 at macro- and microscopic scales

    DEFF Research Database (Denmark)

    Torras-Rosell, Antoni; Johannsen, Sabrina Rostgaard; Dirscherl, Kai

    2016-01-01

    . The photocatalytic properties of TiO2 at macro- and microscopic scales are investigated by comparing photocatalytic degradation of acetone and electrochemical experiments to Kelvin probe force microscopy. The good agreement between the macro- and microscopic experiments suggests that Kelvin probe force microscopy...

  9. Photocatalytic studies of electrochemically synthesized polysaccharide-functionalized ZnO nanoparticles

    Science.gov (United States)

    Kaur, Simranjeet; Kaur, Harpreet

    2018-05-01

    The present work reports the electrochemical synthesis of polysaccharide-functionalized ZnO nanoparticles using sodium hydroxide, starch, and zinc electrodes for the degradation of cationic dye (Rhodamine-B) under sunlight. Physiochemical properties of synthesized sample have been characterized by different techniques such as XRD, TEM, FESEM, EDS, IR, and UV-visible spectroscopic techniques. The influence of various factors such as effect of dye concentration, contact time, amount of photocatalyst, and pH has been studied. The results obtained from the photodegradation study showed that degradation rate of Rhodamine-B dye has been increased with increase of amount of photocatalyst and decreased with increase in initial dye concentration. Furthermore, the kinetics of the degradation has been investigated. It has been found that the photodegradation of Rhodamine-B dye follows pseudo-first-order kinetics and prepared photocatalyst can effectively degrade the cationic dye. Thus, this ecofriendly and efficient photocatalyst can be used for the treatment of dye-contaminated water. This catalyst also showed the antibacterial activity against Bacillus pumilus and Escherichia coli bacterial strains, so the synthesized nanoparticles also have the pharmaceutical properties.

  10. Antibacterial Activity of Electrochemically Synthesized Colloidal Silver Nanoparticles Against Hospital-Acquired Infections

    Science.gov (United States)

    Thuc, Dao Tri; Huy, Tran Quang; Hoang, Luc Huy; Hoang, Tran Huy; Le, Anh-Tuan; Anh, Dang Duc

    2017-06-01

    This study evaluated the antibacterial activity of electrochemically synthesized colloidal silver nanoparticles (AgNPs) against hospital-acquired infections. Colloidal AgNPs were synthesized via a single process using bulk silver bars, bi-distilled water, trisodium citrate, and direct current voltage at room temperature. Colloidal AgNPs were characterized by transmission electron microscopy, field-emission scanning electron microscopy, and energy-dispersive x-ray analyses. The antibacterial activity of colloidal AgNPs against four bacterial strains isolated from clinical samples, including methicillin-resistant Staphylococcus aureus, Escherichia coli O157:H7, multidrug-resistant Pseudomonas aeruginosa, and carbapenem-resistant Klebsiella pneumonia, was evaluated by disc diffusion, minimum inhibitory concentration (MIC), and ultrathin sectioning electron microscopy. The results showed that the prepared AgNPs were 19.7 ± 4.3 nm in size, quasi-spherical, and of high purity. Zones of inhibition approximately 6-10 mm in diameter were found, corresponding to AgNPs concentrations of 50 μg/mL to 100 μg/mL. The MIC results revealed that the antibacterial activity of the prepared AgNPs was strongly dependent on the concentration and strain of the tested bacteria.

  11. In situ glow discharge plasma electrolytic synthesis of reduced TiO2 for enhanced visible light photocatalysis

    Science.gov (United States)

    Feng, Guang; Wu, Botao; Qayyum Khan, Abdul; Zeng, Heping

    2018-05-01

    Reduced titanium dioxide (TiO2‑x) due to its extraordinary visible light absorption has been widely investigated in photodegradation and water splitting nowadays. However, conventional routes to synthesize reduced TiO2 usually demand multiple preparation steps, harsh controlled conditions or expensive facilities. Here we developed a single-step in situ approach to prepare the gray TiO2‑x nanoparticles (sub-10 nm) effectively by the glow discharge plasma electrolysis (GDPE) under atmospheric pressure. The co-existence of self-doped oxygen vacancies and Ti3+ in the generated TiO2‑x nanoparticles is demonstrated by electron paramagnetic resonance (EPR). The tunable ratio of bulk/surface defect can be realized by controlling the glow discharge power directly. It should be noticed that Ti3+ in the synthesized TiO2‑x are quite stable in ambient air. The UV–vis spectra of gray TiO2‑x show an enhanced visible light absorption, which leads to high visible-light photocatalytic activity. Moreover, the as-prepared TiO2‑x after 6 months storage still shows excellent stability during photocatalytic reactions. Owing to its simplicity and effectivity, this preparation method with GDPE should provide a large-scale production for TiO2‑x with high photoactivity.

  12. Direct access to highly crystalline mesoporous nano TiO2 using sterically bulky organic acid templates

    Science.gov (United States)

    Bakre, Pratibha V.; Tilve, S. G.

    2018-05-01

    Sterically bulky monocarboxylic acid templates pivalic acid and phenoxyacetic acid are reported for the first time as organic templates in the sol-gel synthesis of TiO2. Mesoporous nanoparticulates of pure anatase phase and of well defined size were synthesized. The characterization of the materials prepared was done by various methods such as XRD, SEM, TEM, FTIR, UV-DRS, BET, etc. The prepared TiO2 samples were evaluated for the day light photodegradation of methylene blue by comparing with Degussa P25 and templates free synthesized TiO2 and were found to be more efficient.

  13. Synthesis and Characterization of Hierarchical Structured TiO2 Nanotubes and Their Photocatalytic Performance on Methyl Orange

    Directory of Open Access Journals (Sweden)

    Kai Liu

    2015-01-01

    Full Text Available Hierarchical structured TiO2 nanotubes were prepared by mechanical ball milling of highly ordered TiO2 nanotube arrays grown by electrochemical anodization of titanium foil. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, specific surface area analysis, UV-visible absorption spectroscopy, photocurrent measurement, photoluminescence spectra, electrochemical impedance spectra, and photocatalytic degradation test were applied to characterize the nanocomposites. Surface area increased as the milling time extended. After 5 h ball milling, TiO2 hierarchical nanotubes exhibited a corn-like shape and exhibited enhanced photoelectrochemical activity in comparison to commercial P25. The superior photocatalytic activity is suggested to be due to the combined advantages of high surface area of nanoparticles and rapid electron transfer as well as collection of the nanotubes in the hierarchical structure. The hierarchical structured TiO2 nanotubes could be applied into flexible applications on solar cells, sensors, and other photoelectrochemical devices.

  14. Structure and properties of nanophase TiO2

    International Nuclear Information System (INIS)

    Siegel, R.W.; Hahn, H.; Ramasamy, S.; Zongquan, Li; Ting, Lu; Gronsky, R.

    1987-07-01

    Ultrafine-grained, nanophase samples of TiO 2 (rutile) were synthesized by the gas-condensation method and subsequent in-situ compaction, and then studied by transmission electron microscopy, Vickers hardness measurements, and positron annihilation spectroscopy as a function of sintering temperature. The nanophase compacts densified rapidly above 500 0 C, with only a small increase in grain size. The hardness values obtained by this method are comparable to or greater than coarser-grained compacts, but at temperatures 400 to 600 0 C lower than conventional sintering temperatures and without the need for sintering aids. 11 refs., 3 figs

  15. Controlled synthesis of TiO2-B nanowires and nanoparticles for dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Qi Lihong; Liu Yongjun; Li Chunyan

    2010-01-01

    Controllable synthesis of the TiO 2 -B nanowires (NWs) and nanoparticles (NPs) had been achieved via a facile hydrothermal route, respectively, only by tuning the solution volume. The dye-sensitized solar cells prototypes had been fabricated using TiO 2 -B NW and NP electrodes, respectively. The TiO 2 -B NP cells had higher photocurrent and photoelectrical conversion efficiency than the TiO 2 -B NW cells though the latter exhibited larger photovoltage compared to the former. The key factors such as the photogenerated electron injection drive force, surface defects and the interfacial charge transfer, which determined the photoelectrical properties, had been systematically researched with the surface photovoltage spectra (SPS) and the electrochemical impedance spectra (EIS). The SPS proved that there was larger photoelectron injection drive force in TiO 2 -B NP photoelectrode than that in NW photoelectrode. And the electrochemical impedance spectra (EIS) revealed that TiO 2 -B NP cells had faster interface charge transfer compared to TiO 2 -B NW cells. Both proved that NP cells had the higher photocurrents.

  16. Enhanced visible-light photocatalytic activity for selective oxidation of amines into imines over TiO2(B)/anatase mixed-phase nanowires

    International Nuclear Information System (INIS)

    Dai, Jun; Yang, Juan; Wang, Xiaohan; Zhang, Lei; Li, Yingjie

    2015-01-01

    Graphical abstract: Visible-light photocatalytic activities for selective oxidation of amines into imines are greatly affected by the crystal structure of TiO 2 catalysts and mixed-phase TiO 2 (B)/anatase possess higher photoactivity because of the moderate adsorption ability and efficient charge separation. - Highlights: • Visible-light photocatalytic oxidation of amines to imines is studied over different TiO 2 . • Photocatalytic activities are greatly affected by the crystal structure of TiO 2 nanowires. • Mixed-phase TiO 2 (B)/anatase exhibits higher catalytic activity than single-phase TiO 2 . • Enhanced activity is ascribed to efficient adsorption ability and interfacial charge separation. • Photoinduced charge transfer mechanism on TiO 2 (B)/anatase catalysts is also proposed. - Abstract: Wirelike catalysts of mixed-phase TiO 2 (B)/anatase TiO 2 , bare anatase TiO 2 and TiO 2 (B) are synthesized via calcining precursor hydrogen titanate obtained from hydrothermal process at different temperatures between 450 and 700 °C. Under visible light irradiation, mixed-phase TiO 2 (B)/anatase TiO 2 catalysts exhibit enhanced photocatalytic activity in comparison with pure TiO 2 (B) and anatase TiO 2 toward selective oxidation of benzylamines into imines and the highest photocatalytic activity is achieved by TW-550 sample consisting of 65% TiO 2 (B) and 35% anatase. The difference in photocatalytic activities of TiO 2 samples can be attributed to the different adsorption abilities resulted from their crystal structures and interfacial charge separation driven by surface-phase junctions between TiO 2 (B) and anatase TiO 2 . Moreover, the photoinduced charge transfer mechanism of surface complex is also proposed over mixed-phase TiO 2 (B)/anatase TiO 2 catalysts. Advantages of this photocatalytic system include efficient utilization of solar light, general suitability to amines, reusability and facile separation of nanowires catalysts

  17. Synthesis and photocatalytic activity of anatase TiO2 nanoparticles for degradation of methyl orange

    Science.gov (United States)

    Singh, Manmeet; Duklan, Neha; Singh, Pritpal; Sharma, Jeewan

    2018-05-01

    In present study, TiO2 nanoparticles, in anatase form, were successfully synthesized using TiCl4 as precursor. These nanoparticles were synthesized by sol-gel method at room temperature (298 K). As prepared samples were characterized for phase structure, optical absorption and surface properties using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Raman spectroscopy and UV-Visible spectroscopy. The synthesized TiO2 nanoparticles sample was compared with one of the most efficient commercial photocatalyst Degussa TiO2 also known as P(25). The effect of phase composition of anatase TiO2 nanoparticles, as compared to P(25), on photocatalytic decomposition of organic dye, methyl orange (MO) was studies under UV light illumination. An enhanced degradation of hazardous dye was observed in the presence of anatase TiO2 nanoparticles as compared to P(25) due to slow recombination rate. Other possible reasons for this enhancement have also been discussed.

  18. Changes of electrochemical properties of polypyrrole when synthesized in a room-temperature ionic liquid

    Energy Technology Data Exchange (ETDEWEB)

    Dalmolin, Carla, E-mail: carla.dalmolin@udesc.br; Biaggio, Sonia R.; Bocchi, Nerilso; Rocha-Filho, Romeu C.

    2014-09-15

    The room-temperature ionic liquid (RTIL) 1-butyl-3-methylimidazolium tetrafluoroborate, BMIM BF{sub 4}, was employed as electrolyte in the electrosynthesis of thin polypyrrole (PPy) films on a Pt substrate, and the resulting PPy electrodes were electrochemically characterized. Electrochemical impedance spectroscopy (EIS) was used to comparatively investigate the electric behavior of PPy produced in the RTIL and the one produced in a traditional acetonitrile/lithium salt system, and charge–discharge curves in the range 2.0–4.0 V (vs. Li/Li{sup +}) were obtained in a 1.0 M LiBF{sub 4} propylene carbonate solution. Although a reduction of the specific capacity for the PPy obtained in the RTIL was observed, compared to that of the PPy film synthesized in the acetonitrilic electrolyte, its chronopotentiometric profile presented a plateau in the 2.7 V region. This is a remarkable result, considering that a linear decrease in this profile is usually observed for the majority of conducting polymer cathodes. PPy films obtained in BMIM BF{sub 4} presented globular morphology, with a special arrangement of nanoparticles constituting the globules; the EIS results indicated that this nanoscale structure may be contributing to a better definition of the redox characteristics during the PPy charge–discharge processes, as it happens for the well-organized structure of some metal oxides. - Highlights: • PPy was produced in an ionic liquid medium as active material for battery electrodes. • Discharge curves present a plateau not usual for conducting polymer electrodes. • RTIL used as synthesis electrolyte produced PPy with surface nanograins. • Morphological features explain the improved redox properties of PPy electrode. • Electrical properties of PPy grown in RTIL were accessed by impedance measurements.

  19. Formation of hydroxyl radicals and kinetic study of 2-chlorophenol photocatalytic oxidation using C-doped TiO2, N-doped TiO2, and C,N Co-doped TiO2 under visible light.

    Science.gov (United States)

    Ananpattarachai, Jirapat; Seraphin, Supapan; Kajitvichyanukul, Puangrat

    2016-02-01

    This work reports on synthesis, characterization, adsorption ability, formation rate of hydroxyl radicals (OH(•)), photocatalytic oxidation kinetics, and mineralization ability of C-doped titanium dioxide (TiO2), N-doped TiO2, and C,N co-doped TiO2 prepared by the sol-gel method. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV-visible spectroscopy were used to analyze the titania. The rate of formation of OH(•) for each type of titania was determined, and the OH-index was calculated. The kinetics of as-synthesized TiO2 catalysts in photocatalytic oxidation of 2-chlorophenol (2-CP) under visible light irradiation were evaluated. Results revealed that nitrogen was incorporated into the lattice of titania with the structure of O-Ti-N linkages in N-doped TiO2 and C,N co-doped TiO2. Carbon was joined to the Ti-O-C bond in the C-doped TiO2 and C,N co-doped TiO2. The 2-CP adsorption ability of C,N co-doped TiO2 and C-doped TiO2 originated from a layer composed of a complex carbonaceous mixture at the surface of TiO2. C,N co-doped TiO2 had highest formation rate of OH(•) and photocatalytic activity due to a synergistic effect of carbon and nitrogen co-doping. The order of photocatalytic activity per unit surface area was the same as that of the formation rate of OH(•) unit surface area in the following order: C,N co-doped TiO2 > C-doped TiO2 > N-doped TiO2 > undoped TiO2.

  20. Photo catalytic reduction of benzophenone on TiO2: Effect of preparation method and reaction conditions

    International Nuclear Information System (INIS)

    Albiter E, E.; Valenzuela Z, M. A.; Alfaro H, S.; Flores V, S. O.; Rios B, O.; Gonzalez A, V. J.; Cordova R, I.

    2010-01-01

    The photo catalytic reduction of benzophenone was studied focussing on improving the yield to benzhydrol. TiO 2 was synthesized by means of a hydrothermal technique. TiO 2 (Degussa TiO 2 -P25) was used as a reference. Catalysts were characterized by X-ray diffraction and nitrogen physisorption. The photo catalytic reduction was carried out in a batch reactor at 25 C under nitrogen atmosphere, acetonitrile as solvent and isopropanol as electron donor. A 200 W Xe-Hg lamp (λ= 360 nm) was employed as irradiation source. The chemical composition of the reaction system was determined by HPLC. Structural and textural properties of the synthesized TiO 2 depended on the type of acid used during sol formation step. Using HCl, a higher specific surface area and narrower pore size distribution of TiO 2 was obtained in comparison with acetic acid. As expected, the photochemical reduction of benzophenone yielded benzopinacol as main product, whereas, benzhydrol is only produced in presence of TiO 2 (i.e. photo catalytic route). In general, the hydrothermally synthesized catalysts were less active and with a lower yield to benzhydrol. The optimal reaction conditions to highest values of benzhydrol yield (70-80%) were found at 2 g/L (catalyst loading) and 0.5 m M of initial concentration of benzophenone, using commercial TiO 2 -P25. (Author)

  1. Synthesis of mesoporous TiO2 in aqueous alcoholic medium and evaluation of its photocatalytic activity

    International Nuclear Information System (INIS)

    Kumaresan, L.; Prabhu, A.; Palanichamy, M.; Murugesan, V.

    2011-01-01

    Research highlights: → Mesoporous TiO 2 synthesized using P123 as soft template in sol-gel method. → Nanoparticle aggregates are better for photocatalytic activity than free nanoparticles. → Particle to particle transport of electrons in the conduction band of aggregates are important factor. - Abstract: Mesoporous TiO 2 was synthesized using triblock copolymer as the structure directing template in ethanol/water, isopropanol/water or 1-butanol/water medium by sol-gel method. The presence of intense peak at low angle in the XRD patterns confirmed the orderly arrangement of mesopores in the material. Among the three different alcohols, ethanol had influenced better in controlling the particle size than others. The enhanced specific surface area also revealed the formation of mesopores. Aggregates of particles were clearly seen in the TEM images and the size of the particles was approximately 10 nm. The photocatalytic activity of mesoporous TiO 2 was evaluated using aqueous alachlor as a model pollutant. The activity of mesoporous TiO 2 synthesized in ethanol/water mole ratio of 50 was higher than other mesoporous TiO 2 and commercial TiO 2 (Degussa P-25). The transport of excited electrons from one particle to its neighboring nanoparticles of mesoporous TiO 2 is suggested to be the cause for enhanced photocatalytic activity.

  2. Hydrothermal synthesis, characterization, photocatalytic activity and dye-sensitized solar cell performance of mesoporous anatase TiO2 nanopowders

    International Nuclear Information System (INIS)

    Pavasupree, Sorapong; Jitputti, Jaturong; Ngamsinlapasathian, Supachai; Yoshikawa, Susumu

    2008-01-01

    Mesoporous anatase TiO 2 nanopowder was synthesized by hydrothermal method at 130 deg. C for 12 h. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), HRTEM, and Brunauer-Emmett-Teller (BET) surface area. The as-synthesized sample with narrow pore size distribution had average pore diameter about 3-4 nm. The specific BET surface area of the as-synthesized sample was about 193 m 2 /g. Mesoporous anatase TiO 2 nanopowders (prepared by this study) showed higher photocatalytic activity than the nanorods TiO 2 , nanofibers TiO 2 mesoporous TiO 2 , and commercial TiO 2 nanoparticles (P-25, JRC-01, and JRC-03). The solar energy conversion efficiency (η) of the cell using the mesoporous anatase TiO 2 was about 6.30% with the short-circuit current density (Jsc) of 13.28 mA/cm 2 , the open-circuit voltage (Voc) of 0.702 V and the fill factor (ff) of 0.676; while η of the cell using P-25 reached 5.82% with Jsc of 12.74 mA/cm 2 , Voc of 0.704 V and ff of 0.649

  3. Gold nanoparticles-immobilized, hierarchically ordered, porous TiO2 nanotubes for biosensing of glutathione

    Directory of Open Access Journals (Sweden)

    Sheen Mers SV

    2015-10-01

    Full Text Available SV Sheen Mers,1,2 Elumalai Thambuswamy Deva Kumar,1 V Ganesh1,2 1Electrodics and Electrocatalysis (EEC Division, Council of Scientific and Industrial Research–Central Electrochemical Research Institute (CSIR–CECRI, Karaikudi, Tamil Nadu, India; 2Academy of Scientific and Innovative Research (AcSIR, New Delhi, India Abstract: Glutathione (GSH is vital for several functions of our human body such as neutralization of free radicals and reactive oxygen compounds, maintaining the active forms of vitamin C and E, regulation of nitric oxide cycle, iron metabolism, etc. It is also an endogenous antioxidant in most of the biological reactions. Given the importance of GSH, a simple strategy is proposed in this work to develop a biosensor for quantitative detection of GSH. This particular biosensor comprises of gold nanoparticles (Au NPs-immobilized, hierarchically ordered titanium dioxide (TiO2 porous nanotubes. Hexagonally arranged, honeycomb-like nanoporous tubular TiO2 electrodes are prepared by using a simple electrochemical anodization process by applying a constant potential of 30 V for 24 hours using ethylene glycol consisting of ammonium fluoride as an electrolytic medium. Structural morphology and crystalline nature of such TiO2 nanotubes are analyzed using field emission scanning electron microscope (FESEM and X-ray diffraction (XRD. Interestingly, nanocomposites of TiO2 with Au NPs is prepared in an effort to alter the intrinsic properties of TiO2, especially tuning of its band gap. Au NPs are prepared by a well-known Brust and Schiffrin method and are immobilized onto TiO2 electrodes which act as a perfect electrochemical sensing platform for GSH detection. Structural characterization and analysis of these modified electrodes are performed using FESEM, XRD, and UV-visible spectroscopic studies. GSH binding events on Au NPs-immobilized porous TiO2 electrodes are monitored by electrochemical techniques, namely, cyclic voltammetry (CV and

  4. Surface Plasmon Enhanced Photocatalysis of Au/Pt-decorated TiO2 Nanopillar Arrays

    Science.gov (United States)

    Shuang, Shuang; Lv, Ruitao; Xie, Zheng; Zhang, Zhengjun

    2016-05-01

    The low quantum yields and lack of visible light utilization hinder the practical application of TiO2 in high-performance photocatalysis. Herein, we present a design of TiO2 nanopillar arrays (NPAs) decorated with both Au and Pt nanoparticles (NPs) directly synthesized through successive ion layer adsorption and reaction (SILAR) at room temperature. Au/Pt NPs with sizes of ~4 nm are well-dispersed on the TiO2 NPAs as evidenced by electron microscopic analyses. The present design of Au/Pt co-decoration on the TiO2 NPAs shows much higher visible and ultraviolet (UV) light absorption response, which leads to remarkably enhanced photocatalytic activities on both the dye degradation and photoelectrochemical (PEC) performance. Its photocatalytic reaction efficiency is 21 and 13 times higher than that of pure TiO2 sample under UV-vis and visible light, respectively. This great enhancement can be attributed to the synergy of electron-sink function of Pt and surface plasmon resonance (SPR) of Au NPs, which significantly improves charge separation of photoexcited TiO2. Our studies demonstrate that through rational design of composite nanostructures one can harvest visible light through the SPR effect to enhance the photocatalytic activities initiated by UV-light, and thus realize more effectively utilization of the whole solar spectrum for energy conversion.

  5. Improved Visible Light Photocatalytic Activity for TiO2 Nanomaterials by Codoping with Zinc and Sulfur

    Directory of Open Access Journals (Sweden)

    Qianzhi Xu

    2015-01-01

    Full Text Available S/Zn codoped TiO2 nanomaterials were synthesized by a sol-gel method. X-ray diffraction, UV-vis diffuse reflectance spectroscopy, transmission electron microscopy, photoluminescence spectroscopy, and X-ray photoelectron spectroscopy were used to characterize the morphology, structure, and optical properties of the prepared samples. The introduction of Zn and S resulted in significant red shift of absorption edge for TiO2-based nanomaterials. The photocatalytic activity was evaluated by degrading reactive brilliant red X-3B solution under simulated sunlight irradiation. The results showed S/Zn codoped TiO2 exhibited higher photocatalytic activity than pure TiO2 and commercial P25, due to the photosynergistic effect of obvious visible light absorption, efficient separation of photoinduced charge carriers, and large surface area. Moreover, the content of Zn and S in the composites played important roles in photocatalytic activity of TiO2-based nanomaterials.

  6. A Facile Approach to Prepare Black TiO2 with Oxygen Vacancy for Enhancing Photocatalytic Activity

    Science.gov (United States)

    Chen, Shihao; Xiao, Yang; Hu, Zhengfa; Zhao, Hui; Xie, Wei

    2018-01-01

    Black TiO2 has triggered worldwide research interest due to its excellent photocatalytic properties. However, the understanding of its structure–property relationships and a more effective, facile and versatile method to produce it remain great challenges. We have developed a facile approach to synthesize black TiO2 nanoparticles with significantly improved light absorption in the visible and infrared regions. The experimental results show that oxygen vacancies are the major factors responsible for black coloration. More importantly, our black TiO2 nanoparticles have no Ti3+ ions. These oxygen vacancies could introduce localized states in the bandgap and act as trap centers, significantly decreasing the electron–hole recombination. The photocatalytic decomposition of both rhodamine B and methylene blue demonstrated that, under ultraviolet light irradiation, better photocatalytic performance is achieved with our black TiO2 nanoparticles than with commercial TiO2 nanoparticles. PMID:29659500

  7. Synthesis, Structural and Optical Properties of Co Doped TiO2 Nanocrystals by Sol-Gel Method

    Directory of Open Access Journals (Sweden)

    D.V. Sridevi

    2017-06-01

    Full Text Available A TiO2 nanoparticle doped with cobalt was synthesized by sol-gel technique employed at room temperature with appropriate reactants. In the present case, we used titanium tetra isoprotoxide (TTIP and 2–propanol as a common starting material and the obtained products were calcined at 450˚ C. From the Powder XRD data the particle size was calculated by Scherrer method. The FE-SEM analysis shows the morphology of cobalt doped TiO2 nanoparticles. The various functional groups of the samples were identified by Fourier transform spectroscopy (FT-IR. The UV-Vis-NIR spectra of cobalt doped TiO2 material shows two absorption peaks in the visible region related to d-d transitions of Co2+ in TiO2 lattice. Compared to un-doped TiO2 nanoparticles, the cobalt doped material show a red shift in the band gap.

  8. Low-temperature preparation and microwave photocatalytic activity study of TiO2-mounted activated carbon

    International Nuclear Information System (INIS)

    Liu Yazi; Yang Shaogui; Hong Jun; Sun Cheng

    2007-01-01

    TiO 2 thin films were deposited on granular activated carbon by a dip-coating method at low temperature (373 K), using microwave radiation to enhance the crystallization of titania nanoparticles. Uniform and continuous anatase titania films were deposited on the surface of activated carbon. BET surface area of TiO 2 -mounted activated carbon (TiO 2 /AC) decreased a little in comparison with activated carbon. TiO 2 /AC possessed strong optical absorption capacity with a band gap absorption edge around 360 nm. The photocatalytic activity did not increase when the as-synthesized TiO 2 /AC was thermally treated, but was much higher than commercial P-25 in degradation of phenol by irradiation of electrodeless discharge lamps (EDLs)

  9. Room-temperature synthesis of TiO 2 nanospheres and their solar driven photoelectrochemical hydrogen production

    KAUST Repository

    Avasare, Vidya

    2015-08-13

    Highly monodisperse and crystalline anatase phase TiO2 nanospheres have been synthesized at room temperature from organometallic precursor, titanocene dichloride and sodium azide. The photoelectrochemical (PEC) water splitting performance on the TiO2 nanospheres was studied under illumination of AM 1.5G. The optimized photocurrent density and photoconversion efficiency of TiO2 NSPs were observed ~0.95mAcm-2 at 1.23V and 0.69%, respectively. The transient photocurrent response measurements on the TiO2 NSPs during repeated ON/OFF visible light illumination cycles at 1.23V vs RHE show that both samples exhibited fast and reproducible photocurrent responses. The TiO2 NSPs show excellent catalytic stability, and significant dark current was not observed even at high potentials (2.0V vs RHE). © 2015 John Wiley & Sons, Ltd.

  10. Preparation, characterization of Fe3O4 at TiO2 magnetic nanoparticles and their application for immunoassay of biomarker of exposure to organophosphorus pesticides

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiao; Wang, Hongbo; Yang, Chunming; Du, Dan; Lin, Yuehe

    2013-03-15

    Novel Fe3O4 at TiO2 magnetic nanoparticles were prepared and developed for a new nanoparticle-based immunosensor for electrochemical quantification of organophosphorylated butyrylcholinesterase (BChE) in plasma, a specific biomarker of exposure to organophosphorus (OP) agents. The Fe3O4 at TiO2 nanoparticles were synthesized by hydrolysis of tetrabutyltitanate on the surface of Fe3O4 magnetic nanospheres, and characterized by attenuated total reflection Fourier-transform infrared spectra, transmission electron microscope and X-ray diffraction. The functional Fe3O4 at TiO2 nanoparticles were performed as capture antibody to selectively enrich phosphorylated moiety instead of phosphoserine antibody in the traditional sandwich immunoassays. The secondary recognition was served by quantum dots (QDs)-tagged anti-BChE antibody (QDs-anti-BChE). With the help of a magnet, the resulting sandwich-like complex, Fe3O4 at TiO2/OP-BChE/QDs-anti-BChE, was easily isolated from sample solutions and the released cadmium ions were detected on a disposable screen-printed electrode (SPE). The binding affinities were investigated by both surface plasmon resonance (SPR) and square wave voltammetry (SWV). This method not only avoids the drawback of unavailability of commercial OP-specific antibody but also amplifies detection signal by QDs-tags together with easy separation of samples by magnetic forces. The proposed immunosensor yields a linear response over a broad OP-BChE concentrations range from 0.02 to 10 nM, with detection limit of 0.01 nM. Moreover, the disposable nanoparticle-based immunosensor has been validated with human plasma samples. It offers a new method for rapid, sensitive, selective and inexpensive screening/evaluating exposure to OP pesticides.

  11. TiO2-Based Nanomaterials for Gas Sensing-Influence of Anatase and Rutile Contributions.

    Science.gov (United States)

    Zakrzewska, K; Radecka, M

    2017-12-01

    The paper deals with application of three nanomaterial systems: undoped TiO 2 , chromium-doped TiO 2 :Cr and TiO 2 -SnO 2 synthesized by flame spray synthesis (FSS) technique for hydrogen sensing. The emphasis is put on the role of anatase and rutile polymorphic forms of TiO 2 in enhancing sensitivity towards reducing gases. Anatase-to-rutile transformation is achieved by annealing of undoped TiO 2 in air at 700 °C, specific Cr doping and modification with SnO 2 . Undoped TiO 2 and TiO 2 -SnO 2 exhibit n-type behaviour and while TiO 2 : 5 at.% Cr is a p-type semiconductor. X-ray diffraction (XRD) has been applied to determine anatase-to-rutile weight ratio as well as anatase and rutile crystal size. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) have been used to characterize the structure and morphological parameters. Optical reflectometry enabled to find and compare the band gaps E g of anatase and rutile predominated compositions. Electrical properties, i.e. the electrical conductivity and values of constant phase element (CPE), have been established on the basis of impedance spectroscopy. Dynamic responses of the electrical resistance as a function of hydrogen concentration revealed that predominance of rutile in anatase/rutile mixture is beneficial for gas sensing. Partial transformation to rutile in all three material systems under study resulted in an increased sensitivity towards hydrogen. It is proposed that this effect can be explained in a similar way as in photocatalysis, i.e. by specific band alignment and electron transfer from rutile to anatase to facilitate oxygen preadsorption on the surface of anatase grains.

  12. CdS-sensitized TiO2 nanocorals: hydrothermal synthesis, characterization, application.

    Science.gov (United States)

    Mali, S S; Desai, S K; Dalavi, D S; Betty, C A; Bhosale, P N; Patil, P S

    2011-10-01

    Cadmium sulfide (CdS) nanoparticle-sensitized titanium oxide nanocorals (TNC) were synthesized using a two-step deposition process. The TiO(2) nanocorals were grown on the conducting glass substrates (FTO) using A hydrothermal process and CdS nanoparticles were loaded on TNC using successive ionic layer adsorption and reaction (SILAR) method. The TiO(2), CdS and TiO(2)-CdS samples were characterized by optical absorption, X-ray diffraction (XRD), FT-Raman, FT-IR, scanning electron microscopy (SEM) and contact angle. Further, their photoelectrochemical (PEC) performance was tested in NaOH, Na(2)S-NaOH-S and Na(2)S electrolytes, respectively. When CdS nanoparticles are coated on TNCs, the optical absorption is found to be enhanced and band edge is red-shifted towards visible region. The TiO(2)-CdS sample exhibits improved photoelectrochemical (PEC) performance with maximum short circuit current of (J(sc)) 1.04 mA cm(-2). After applying these TiO(2)-CdS electrodes in photovoltaic cells, the photocurrent was found to be enhanced by 2.7 and 32.5 times, as compared with those of bare CdS and TiO(2) nanocorals films electrodes respectively. Also, the power conversion efficiency of TiO(2)-CdS electrodes is 0.72%, which is enhanced by about 16 and 29 times for TiO(2), CdS samples. This journal is © The Royal Society of Chemistry and Owner Societies 2011

  13. Characterization and improved solar light activity of vanadium doped TiO2/diatomite hybrid catalysts.

    Science.gov (United States)

    Wang, Bin; Zhang, Guangxin; Leng, Xue; Sun, Zhiming; Zheng, Shuilin

    2015-03-21

    V-doped TiO2/diatomite composite photocatalysts with different vanadium concentrations were synthesized by a modified sol-gel method. The diatomite was responsible for the well dispersion of TiO2 nanoparticles on the matrix and consequently inhibited the agglomeration. V-TiO2/diatomite hybrids showed red shift in TiO2 absorption edge with enhanced absorption intensity. Most importantly, the dopant energy levels were formed in the TiO2 bandgap due to V(4+) ions substituted to Ti(4+) sites. The 0.5% V-TiO2/diatomite photocatalyst displayed narrower bandgap (2.95 eV) compared to undoped sample (3.13 eV) and other doped samples (3.05 eV) with higher doping concentration. The photocatalytic activities of V doped TiO2/diatomite samples for the degradation of Rhodamine B under stimulated solar light illumination were significantly improved compared with the undoped sample. In our case, V(4+) ions incorporated in TiO2 lattice were responsible for increased visible-light absorption and electron transfer to oxygen molecules adsorbed on the surface of TiO2 to produce superoxide radicals ˙O2(-), while V(5+) species presented on the surface of TiO2 particles in the form of V2O5 contributed to e(-)-h(+) separation. In addition, due to the combination of diatomite as support, this hybrid photocatalyst could be separated from solution quickly by natural settlement and exhibited good reusability. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. TiO2/Pt/TiO2 Sandwich Nanostructures: Towards Alcohol Sensing and UV Irradiation-Assisted Recovery

    Directory of Open Access Journals (Sweden)

    Rungroj Maolanon

    2017-01-01

    Full Text Available The TiO2/Pt/TiO2 sandwich nanostructures were synthesized by RF magnetron sputtering and demonstrated as an alcohol sensor at room-temperature operation with a fast recovery by UV irradiation. The TiO2/Pt/TiO2 layers on SiO2/Si substrate were confirmed by Auger electron spectroscopy with the interdiffusion of each layer. The TiO2/Pt/TiO2 layers on printed circuit board show the superior sensor response to alcohol in terms of the sensitivity and stability compared to the nonsandwich structure, that is, the only Pt layer or the TiO2/Pt structures. Moreover, the recovery time of the TiO2/Pt/TiO2 was improved by UV irradiation-assisted recovery. The optimum TiO2/Pt/TiO2 with thicknesses of the undermost TiO2 layer, a Pt layer, and the topmost TiO2 layer being 50 nm, 6 nm, and 5 nm, respectively, showed the highest response to ethanol down to 10 ppm. Additionally, TiO2/Pt/TiO2 shows an excellent sensing stability and exhibits different sensing selectivity among ethanol, methanol, and 2-propanol. The sensing mechanism could be attributed to the change of Pt work function during vapor adsorption. The TiO2 layer plays an important role in UV-assisted recovery by photocatalytic activity and the topmost TiO2 acts as protective layer for Pt.

  15. High cyclability of carbon-coated TiO2 nanoparticles as anode for sodium-ion batteries

    International Nuclear Information System (INIS)

    Ge, Yeqian; Jiang, Han; Zhu, Jiadeng; Lu, Yao; Chen, Chen; Hu, Yi; Qiu, Yiping; Zhang, Xiangwu

    2015-01-01

    Highlights: • Titanium oxide nanopaticles were modified by carbon coating from pyrolyzing of PVP. • Carbon coating gave rise to excellent cycling ability of TiO 2 for sodium-ion batteries. • The reversible capacity of carbon-coated TiO 2 reached 242.3 mAh g −1 at 30 mA g −1 . • Good rate performance of carbon-coated TiO 2 was presented up to 800 mA g −1 . - Abstract: Owing to the merits of good chemical stability, elemental abundance and nontoxicity, titanium dioxide (TiO 2 ) has drawn increasing attraction for use as anode material in sodium-ion batteries. Nanostructured TiO 2 was able to achieve high energy density. However, nanosized TiO 2 is typically electrochemical instable, which leads to poor cycling performance. In order to improve the cycling stability, carbon from thermolysis of poly(vinyl pyrrolidone) was coated onto TiO 2 nanoparticles. Electronic conductivity and electrochemical stability were enhanced by coating carbon onto TiO 2 nanoparticles. The resultant carbon-coated TiO 2 nanoparticles exhibited high reversible capacity (242.3 mAh g −1 ), high coulombic efficiency (97.8%), and good capacity retention (87.0%) at 30 mA g −1 over 100 cycles. By comparison, untreated TiO 2 nanoparticles showed comparable reversible capacity (237.3 mAh g −1 ) and coulombic efficiency (96.2%), but poor capacity retention (53.2%) under the same condition. The rate performance of carbon-coated TiO 2 nanoparticles was also displayed as high as 127.6 mAh g −1 at a current density of 800 mA g −1 . The improved cycling performance and rate capability were mostly attributed to protective carbon layer helping stablize solid electrolyte interface formation of TiO 2 nanoparticles and improving the electronic conductivity. Therefore, it is demonstrated that carbon-coated TiO 2 nanoparticles are promising anode candidate for sodium-ion batteries

  16. Thermal stability and electrochemical properties of PVP-protected Ru nanoparticles synthesized at room temperature

    Science.gov (United States)

    Kumar, Manish; Devi, Pooja; Shivling, V. D.

    2017-08-01

    Stable ruthenium nanoparticles (RuNPs) have been synthesized by the chemical reduction of ruthenium trichloride trihydrate (RuCl3 · 3H2O) using sodium borohydride (NaBH4) as a reductant and polyvinylpyrrolidone (PVP) as a protecting agent in the aqueous medium at room temperature. The nanoparticles thus prepared were characterized by their morphology and structural analysis from transmission electron microscopy (TEM), X-ray powder diffraction (XRD), UV-vis spectroscopy, Fourier transformation infrared and thermogravimetric analysis (TGA) techniques. The TEM image suggested a homogeneous distribution of PVP-protected RuNPs having a small average diameter of 2-4 nm with a chain-like network structure. The XRD pattern also confirmed that a crystallite size is around 2 nm of PVP-protected RuNPs having a single broad peak. The thermal stability studied using TGA, indicated good stability and the electrochemical properties of these nanoparticles revealed that saturation current increases for PVP-protected RuNPs/GC.

  17. Solvothermal synthesis and high optical performance of three-dimensional sea-urchin-like TiO2

    International Nuclear Information System (INIS)

    Zhou, Yi; Wang, Yutang; Li, Mengyao; Li, Xuzhi; Yi, Qin; Deng, Pan; Wu, Hongyan

    2015-01-01

    Graphical abstract: I–V characteristics of different TiO 2 microspheres based DSSCs (a) 3D sphere-like, (b) 3D flower-like, (c) 3D sea-urchin-like. - Highlights: • 3D sea-urchin-like TiO 2 was synthesized by solvothermal method. • The effects of preparation parameters on the microstructure of the microspheres were investigated. • The photoelectric properties of 3D sea-urchin-like TiO 2 were studied upon DSSCs. • The PCE of the 3D sea-urchin-like TiO 2 was higher than that of other morphologies. - Abstract: Three-dimensional (3D) sea-urchin-like TiO 2 microspheres were successfully synthesised by solvothermal method. The effects of preparation parameters including reaction temperature, concentration and mass fraction of precursor, and solvent volume on the microstructure of the microspheres were investigated. Results of scanning electron microscopy showed that the preparation parameters played a critical role in the morphology of 3D sea-urchin-like TiO 2 . In addition, when the sea-urchin-like TiO 2 nanostructures were used as the dye-sensitized solar cells (DSSCs) anode, the power-conversion efficiency was higher than that of other morphologies, which was due to the special 3D hierarchical nanostructure, large specific surface area, and enhanced absorption of UV–vis of the TiO 2 nanostructures

  18. Photocathodic Protection of 304 Stainless Steel by Bi2S3/TiO2 Nanotube Films Under Visible Light.

    Science.gov (United States)

    Li, Hong; Wang, Xiutong; Wei, Qinyi; Hou, Baorong

    2017-12-01

    We report the preparation of TiO 2 nanotubes coupled with a narrow bandgap semiconductor, i.e., Bi 2 S 3 , to improve the photocathodic protection property of TiO 2 for metals under visible light. Bi 2 S 3 /TiO 2 nanotube films were successfully synthesized using the successive ionic layer adsorption and reaction (SILAR) method. The morphology and structure of the composite films were studied by scanning electron microscopy and X-ray diffraction, respectively. UV-visible diffuse reflectance spectra were recorded to analyze the optical absorption property of the composite films. In addition, the influence of Bi 2 S 3 deposition cycles on the photoelectrochemical and photocathodic protection properties of the composite films was also studied. Results revealed that the heterostructure comprised crystalline anatase TiO 2 and orthorhombic Bi 2 S 3 and exhibited a high visible light response. The photocurrent density of Bi 2 S 3 /TiO 2 was significantly higher than that of pure TiO 2 under visible light. The sensitization of Bi 2 S 3 enhanced the separation efficiency of the photogenerated charges and photocathodic protection properties of TiO 2 . The Bi 2 S 3 /TiO 2 nanotubes prepared by SILAR deposition with 20 cycles exhibited the optimal photogenerated cathodic protection performance on the 304 stainless steel under visible light.

  19. Photocathodic Protection of 304 Stainless Steel by Bi2S3/TiO2 Nanotube Films Under Visible Light

    Science.gov (United States)

    Li, Hong; Wang, Xiutong; Wei, Qinyi; Hou, Baorong

    2017-01-01

    We report the preparation of TiO2 nanotubes coupled with a narrow bandgap semiconductor, i.e., Bi2S3, to improve the photocathodic protection property of TiO2 for metals under visible light. Bi2S3/TiO2 nanotube films were successfully synthesized using the successive ionic layer adsorption and reaction (SILAR) method. The morphology and structure of the composite films were studied by scanning electron microscopy and X-ray diffraction, respectively. UV-visible diffuse reflectance spectra were recorded to analyze the optical absorption property of the composite films. In addition, the influence of Bi2S3 deposition cycles on the photoelectrochemical and photocathodic protection properties of the composite films was also studied. Results revealed that the heterostructure comprised crystalline anatase TiO2 and orthorhombic Bi2S3 and exhibited a high visible light response. The photocurrent density of Bi2S3/TiO2 was significantly higher than that of pure TiO2 under visible light. The sensitization of Bi2S3 enhanced the separation efficiency of the photogenerated charges and photocathodic protection properties of TiO2. The Bi2S3/TiO2 nanotubes prepared by SILAR deposition with 20 cycles exhibited the optimal photogenerated cathodic protection performance on the 304 stainless steel under visible light.

  20. Photogenerated cathode protection properties of nano-sized TiO2/WO3 coating

    International Nuclear Information System (INIS)

    Zhou Minjie; Zeng Zhenou; Zhong Li

    2009-01-01

    Nano-sized TiO 2 /WO 3 bilayer coatings were prepared on type 304 stainless steel substrate by sol-gel method. The performance of photo-electrochemical and photogenerated cathode protection of the coating was investigated by the electrochemical method. The results show that the bilayer coating with four TiO 2 layers and three WO 3 layers exhibits the highest photo-electrochemical efficiency and the best corrosion resistance property. Type 304 stainless steel with the coating can maintain cathode protection for 6 h in the dark after irradiation by UV illumination for 1 h. In addition, the mechanism of the photogenerated cathode protection for the bilayer coating was also explored.

  1. Properties of Sn-doped TiO2 nanotubes fabricated by anodization of co-sputtered Ti–Sn thin films

    International Nuclear Information System (INIS)

    Kyeremateng, Nana Amponsah; Hornebecq, Virginie; Knauth, Philippe; Djenizian, Thierry

    2012-01-01

    Self-organized Sn-doped TiO 2 nanotubes (nts) were fabricated for the first time, by anodization of co-sputtered Ti and Sn thin films. This nanostructured material was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, UV–vis spectroscopy and transmission electron microscopy. Due to their remarkable properties, Sn-doped TiO 2 nts can find potential applications in Li-ion microbatteries, photovoltaics, and catalysis. Particularly, the electrochemical performance as an anode material for Li-ion microbatteries was evaluated in Li test cells. With current density of 70 μA cm −2 (1 C) and cut-off potential of 1 V, Sn-doped TiO 2 nts showed improved performance compared to simple TiO 2 nts, and differential capacity plots revealed that the material undergoes full electrochemical reaction as a Rutile-type TiO 2 .

  2. Amorphous and crystalline TiO2 nanotube arrays for enhanced Li-ion intercalation properties.

    Science.gov (United States)

    Guan, Dongsheng; Cai, Chuan; Wang, Ying

    2011-04-01

    We have employed a simple process of anodizing Ti foils to prepare TiO2 nanotube arrays which show enhanced electrochemical properties for applications as Li-ion battery electrode materials. The lengths and pore diameters of TiO2 nanotubes can be finely tuned by varying voltage, electrolyte composition, or anodization time. The as-prepared nanotubes are amorphous and can be converted into anatase nanotubes with heat treatment at 480 degrees C. Rutile crystallites emerge in the anatase nanotube when the annealing temperature is increased to 580 degrees C, resulting in TiO2 nanotubes of mixed phases. The morphological features of nanotubes remain unchanged after annealing. Li-ion insertion performance has been studied for amorphous and crystalline TiO2 nanotube arrays. Amorphous nanotubes with a length of 3.0 microm and an outer diameter of 125 nm deliver a capacity of 91.2 microA h cm(-2) at a current density of 400 microA cm(-2), while those with a length of 25 microm and an outer diameter of 158 nm display a capacity of 533 microA h cm-2. When the 3-microm long nanotubes become crystalline, they deliver lower capacities: the anatase nanotubes and nanotubes of mixed phases show capacities of 53.8 microA h cm-2 and 63.1 microA h cm(-2), respectively at the same current density. The amorphous nanotubes show excellent capacity retention ability over 50 cycles. The cycled nanotubes show little change in morphology compared to the nanotubes before electrochemical cycling. All the TiO2 nanotubes demonstrate higher capacities than amorphous TiO2 compact layer reported in literature. The amorphous TiO2 nanotubes with a length of 1.9 microm exhibit a capacity five times higher than that of TiO2 compact layer even when the nanotube array is cycled at a current density 80 times higher than that for the compact layer. These results suggest that anodic TiO2 nanotube arrays are promising electrode materials for rechargeable Li-ion batteries.

  3. Half-Cell Potential Analysis of an Ammonia Sensor with the Electrochemical Cell Au | YSZ | Au, V2O5-WO3-TiO2

    Directory of Open Access Journals (Sweden)

    Maximilian Fleischer

    2013-04-01

    Full Text Available Half-cell potentials of the electrochemical cell Au, VWT | YSZ | Au are analyzed in dependence on oxygen and ammonia concentration at 550 °C. One of the gold electrodes is covered with a porous SCR catalyst, vanadia-tungstenia-titania (VWT. The cell is utilized as a potentiometric ammonia gas sensor and provides a semi-logarithmic characteristic curve with a high NH3 sensitivity and selectivity. The analyses of the Au | YSZ and Au, VWT | YSZ half-cells are conducted to describe the non-equilibrium behavior of the sensor device in light of mixed potential theory. Both electrode potentials provide a dependency on the NH3 concentration, whereby VWT, Au | YSZ shows a stronger effect which increases with increasing VWT coverage. The potential shifts in the anodic direction confirm the formation of mixed potentials at both electrodes resulting from electrochemical reactions of O2 and NH3 at the three-phase boundary. Polarization curves indicate Butler-Volmer-type kinetics. Modified polarization curves of the VWT covered electrode show an enhanced anodic reaction and an almost unaltered cathodic reaction. The NH3 dependency is dominated by the VWT coverage and it turns out that the catalytic properties of the VWT thick film are responsible for the electrode potential shift

  4. Eosin-Y sensitized core-shell TiO2-ZnO nano-structured photoanodes for dye-sensitized solar cell applications.

    Science.gov (United States)

    Manikandan, V S; Palai, Akshaya K; Mohanty, Smita; Nayak, Sanjay K

    2018-06-01

    In the current investigation, TiO 2 and TiO 2 -ZnO (core-shell) spherical nanoparticles were synthesized by simple combined hydrolysis and refluxing method. A TiO 2 core nanomaterial on the shell material of ZnO was synthesized by utilizing variable ratios of ZnO. The structural characterization of TiO 2 -ZnO core/shell nanoparticles were done by XRD analysis. The spherical structured morphology of the TiO 2 -ZnO has been confirmed through field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) studies. The UV-visible spectra of TiO 2 -ZnO nanostructures were also compared with the pristine TiO 2 to investigate the shift of wavelength. The TiO 2 -ZnO core/shell nanoparticles at the interface efficiently collect the photogenarated electrons from ZnO and also ZnO act a barrier for reduced charge recombination of electrolyte and dye-nanoparticles interface. This combination improved the light absorption which induced the charge transfer ability and dye loading capacity of core-shell nanoparticles. An enhancement in the short circuit current (J sc ) from 1.67 mA/cm 2 to 2.1 mA/cm 2 has been observed for TiO 2 -ZnObased photoanode (with platinum free counter electrode), promises an improvement in the energy conversion efficiency by 57% in comparison with that of the DSSCs based on the pristine TiO 2 . Henceforth, TiO 2 -ZnO photoelectrode in ZnO will effectively act as barrier at the interface of TiO 2 -ZnO and TiO 2 , ensuring the potential for DSSC application. Copyright © 2018 Elsevier B.V. All rights reserved.

  5. TiO2/EVOH based reactive interlayer in Surlyn for organic device encapsulation

    International Nuclear Information System (INIS)

    Kopanati, Gayathri N; Madras, Giridhar; Ramamurthy, Praveen C

    2016-01-01

    Barrier materials are important for improving the stability and lifetimes of organic electronic devices. A simple technique for improving the barrier properties of polymer films was considered in this work by using TiO 2 nanoparticles in the interlayer to be incorporated in the polymer film. TiO 2 was synthesized by the solution combustion technique, was further functionalized using stearic acid or octadecylamine to induce hydrophobicity and enhance processing of the composite interlayer. The grafting of these compounds on to TiO 2 was investigated using Fourier transform infrared spectroscopy, Raman spectroscopy, elemental analysis and thermo-gravimetric analysis. The functionalized and neat TiO 2 were blended with poly (vinyl alcohol-ethylene) (EVOH) and were melt compressed between Surlyn films. The resulting nanocomposite films were tested for their transparency and barrier properties using UV–visible spectroscopy and calcium degradation test, respectively. Further, the effectiveness of these barrier films in encapsulating organic devices was determined from accelerated aging tests. Therefore, the synthesized barrier films with neat and functionalized TiO 2 in the interlayers proved to be effective as moisture barrier composite films. (paper)

  6. Preparation and solar-light photocatalytic activity of TiO2 composites: TiO2/kaolin, TiO2/diatomite, and TiO2/zeolite

    Science.gov (United States)

    Li, Y.; Li, S. G.; Wang, J.; Li, Y.; Ma, C. H.; Zhang, L.

    2014-12-01

    Three TiO2 loaded composites, TiO2/kaolin, TiO2/diatomite, and TiO2/zeolite, were prepared in order to improve the solar-light photocatalytic activity of TiO2. The results showed that the photocatalytic activity could obviously be enhanced by loading appropriate amount of inorganic mineral materials. Meanwhile, TiO2 content, heat-treatment temperature and heat-treatment time on the photocatalytic activity were reviewed. Otherwise, the effect of solar light irradiation time and dye concentration on the photocatalytic degradation of Acid Red B was investigated. Furthermore, the degradation mechanism and adsorption process were also discussed.

  7. Electrocatalytic glucose oxidation via hybrid nanomaterial catalyst of multi-wall TiO2 nanotubes supported Ni(OH)2 nanoparticles: Optimization of the loading level

    International Nuclear Information System (INIS)

    Gu, Yingying; Liu, Yicheng; Yang, Haihong; Li, Benqiang; An, Yarui

    2015-01-01

    Highlights: • Multi-wall TiO 2 nanotube supported Ni(OH) 2 nanoparticles, Ni(OH) 2 /TNTs, was prepared and investigated as anode electro-catalysts for glucose oxidation. • Ni(OH) 2 -24.2%/TNTs obtains the best catalytic activity. • Compared with Ni(OH) 2, the current density of Ni(OH) 2 -24.2%/TNTs increased 5.9 times in 0.1 M NaOH solution. - Abstract: The novel hybrid nanomaterial catalyst of multi-wall TiO 2 nanotube supported Ni(OH) 2 nanoparticles (Ni(OH) 2 /TNTs) was prepared through hydrothermal method and investigated as anode electro-catalysts for glucose oxidation. The nanostructure was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), thermogravimetry-differential thermal analysis (TGA) and nitrogen adsorption-desorption (BET-BJH). The electrochemical performance was measured by a range of electrochemical measurements. Compared with Ni(OH) 2 , the current density of Ni(OH) 2 /TNTs modified GC electrode increased 5.9 times in 0.1 M NaOH solution. The results indicated that the synthesized nanoparticles exhibited good electro-catalytic activity and stability for glucose oxidation. Meanwhile, the hybrid nanomaterial of Ni(OH) 2 /TNTs may be a potential candidate catalyst for direct glucose fuel cell

  8. CdSxSe1−x alloyed quantum dots-sensitized solar cells based on different architectures of anodic oxidation TiO2 film

    International Nuclear Information System (INIS)

    Li, Zhen; Yu, Libo; Liu, Yingbo; Sun, Shuqing

    2014-01-01

    Nanostructured TiO 2 translucent films with different architectures including TiO 2 nanotube (NT), TiO 2 nanowire (NW), and TiO 2 nanowire/nanotube (NW/NT) have been produced by second electrochemical oxidization of TiO 2 NT with diameter around 90–110 nm via modulation of applied voltage. These TiO 2 architectures are sensitized with CdS x Se 1−x alloyed quantum dots (QDs) in sizes of around 3–5 nm aiming to tune the response of the photoelectrochemical properties in the visible region. One-step hydrothermal method facilitates the deposition of CdS x Se 1−x QDs onto TiO 2 films. These CdS x Se 1−x QDs exhibit a tunable range of light absorption with changing the feed molar ratio of S:Se in precursor solution, and inject electrons into TiO 2 films upon excitation with visible light, enabling their application as photosensitizers in sensitized solar cells. Power conversion efficiency (PCE) of 2.00, 1.72, and 1.06 % are achieved with CdS x Se 1−x (obtained with S:Se = 0:4) alloyed QDs sensitized solar cells based on TiO 2 NW/NT, TiO 2 NW, and TiO 2 NT architectures, respectively. The significant enhancement of power conversion efficiency obtained with the CdS x Se 1−x /TiO 2 NW/NT solar cell can be attributed to the extended absorption of light region tuned by CdS x Se 1−x alloyed QDs and enlarged deposition of QDs and efficient electrons transport provided by TiO 2 NW/NT architecture

  9. Fabrication of doped TiO2 nanotube array films with enhanced photo-catalytic activity

    Science.gov (United States)

    Peighambardoust, Naeimeh-Sadat; Khameneh-asl, Shahin; Khademi, Adib

    2018-01-01

    In the present work, we investigate the N and Fe-doped TiO2 nanotube array film prepared by treating TiO2 nanotube array film with ammonia solution and anodizing in Fe(NO3)3 solution respectively. This method avoided the use of hazardous ammonia gas, or laborious ion implantation process. N and Fe-doped TiO2 nanotube arrays (TiO2 NTs) were prepared by electrochemical anodization process in 0.5 wt % HF aqueous solution. The anodization was performed at the conditions of 20 V and 20 min, Followed by a wet immersion in NH3.H2O (1M) for N-doping for 2 hr and annealing post-treatment at 450 °C. The morphology and structure of the nanotube films were characterized by field emission scanning electron microscope (FESEM) and EDX. UV-vis. illumination test were done to observe photo-enhanced catalysis. The effect of different annealing temperature on the structure and photo-absorption property of the TiO2-TNTs was investigated. The results showed that N-TNTs nanotubes exhibited higher photocatalytic activity compared whit the Fe-doped and pure TNTs, because doping N promoted the separation of the photogenerated electrons and holes.

  10. Photolithographically Patterned TiO2 Films for Electrolyte-Gated Transistors.

    Science.gov (United States)

    Valitova, Irina; Kumar, Prajwal; Meng, Xiang; Soavi, Francesca; Santato, Clara; Cicoira, Fabio

    2016-06-15

    Metal oxides constitute a class of materials whose properties cover the entire range from insulators to semiconductors to metals. Most metal oxides are abundant and accessible at moderate cost. Metal oxides are widely investigated as channel materials in transistors, including electrolyte-gated transistors, where the charge carrier density can be modulated by orders of magnitude upon application of relatively low electrical bias (2 V). Electrolyte gating offers the opportunity to envisage new applications in flexible and printed electronics as well as to improve our current understanding of fundamental processes in electronic materials, e.g. insulator/metal transitions. In this work, we employ photolithographically patterned TiO2 films as channels for electrolyte-gated transistors. TiO2 stands out for its biocompatibility and wide use in sensing, electrochromics, photovoltaics and photocatalysis. We fabricated TiO2 electrolyte-gated transistors using an original unconventional parylene-based patterning technique. By using a combination of electrochemical and charge carrier transport measurements we demonstrated that patterning improves the performance of electrolyte-gated TiO2 transistors with respect to their unpatterned counterparts. Patterned electrolyte-gated (EG) TiO2 transistors show threshold voltages of about 0.9 V, ON/OFF ratios as high as 1 × 10(5), and electron mobility above 1 cm(2)/(V s).

  11. Self-Assembled TiO2 Nanotube Arrays with U-Shaped Profile by Controlling Anodization Temperature

    Directory of Open Access Journals (Sweden)

    Jingfei Chen

    2010-01-01

    Full Text Available TiO2 nanotube arrays with uniform diameter from top to bottom were fabricated. The synthesizing approach is based on the investigation of the influence of electrolyte temperature on the tube diameter. We found that the inner diameter of the tubes increased with the electrolyte temperature. Accordingly, we improved the tube profile from the general V shape to U shape by raising the electrolyte temperature gradually. This is a simple and fast approach to fabricate uniform TiO2 nanotubes in diameter. The improved TiO2 nanotube arrays may show better properties and have broad potential applications.

  12. Nanoporous MnO{sub x} thin-film electrodes synthesized by electrochemical lithiation/delithiation for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Hui; Lai, Man On; Lu, Li [Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576 (Singapore)

    2011-02-15

    Nanoporous MnO{sub x} thin-film electrodes are synthesized using a combination of pulsed laser deposition (PLD) and electrochemical lithiation/delithiation methods. A dense Mn{sub 3}O{sub 4} thin-film deposited by PLD can transform into a nanoporous MnO{sub x} thin-film after electrochemical lithiation/delithiation. A nanoporous MnO{sub x} thin-film electrode exhibits significantly improved supercapacitive performance compared with an as-deposited Mn{sub 3}O{sub 4} thin-film electrode. A MnO{sub x} thin-film finally transforms into a MnO{sub 2} thin-film through an electrochemical oxidation process during continuous cyclic voltammetry scanning. (author)

  13. Spectroscopic and Electrochemical Properties of Lithium-Rich LiFePO4 Cathode Synthesized by Solid-State Reaction

    Science.gov (United States)

    Rosaiah, P.; Hussain, O. M.; Zhu, Jinghui; Qiu, Yejun

    2017-08-01

    Lithium iron phosphate (Li x FePO4) is synthesized by a solid-state reaction method. The structural, electrical and electrochemical properties are studied in detail. It is found that the increment of lithium concentration (up to x = 1.05) does not affect the structure of LiFePO4 but improves its electrical conductivity as well as electrochemical performance. Surface morphological studies exhibited the formation of rod-like nanoparticles with small size. Electric and dielectric properties are also investigated over a frequency range of 1 Hz-1 MHz at different temperatures. The conductivity increased with increasing temperature, which follows the Arrhenius relation with the activation energy of about 0.31 eV. And the electrochemical tests found that the Li1.05FePO4 cathode possessed improved discharge capacity with better cycling performance.

  14. Synthesis, Characterization and Properties of CeO2-doped TiO2 Composite Nanocrystals

    Directory of Open Access Journals (Sweden)

    Oman ZUAS

    2013-12-01

    Full Text Available Pure TiO2 and CeO2-doped TiO2 (3 % CeO2-97 %TiO2 composite nanocrystals were synthesized via co-precipitation method and characterized using TGA, XRD, FTIR, DR-UV-vis and TEM. The XRD data revealed that the phase structure of the synthesized samples was mainly in pure anatase having crystallite size in the range of 7 nm – 11 nm. Spherical shapes with moderate aggregation of the crystal particles were observed under the TEM observation. The presence of the CeO2 at TiO2 site has not only affected morphologically but also induced the electronic property of the TiO2 by lowering the band gap energy from 3.29 eV (Eg-Ti to 3.15 eV (Eg-CeTi. Performance evaluation of the synthesized samples showed that both samples have a strong adsorption capacity toward Congo red (CR dye in aqueous solution at room temperature experiment, where  the capacity of the CeTi was higher than the Ti sample. Based on DR-UV data, the synthesized samples obtained in this study may also become promising catalysts for photo-assisted removal of synthetic dye in aqueous solution. DOI: http://dx.doi.org/10.5755/j01.ms.19.4.2732

  15. Study on photocatalysis of TiO2 nanotubes prepared by methanol ...

    Indian Academy of Sciences (India)

    TiO2 nanotubes were synthesized by the solvothermal process at low temperature in a highly alkaline water–methanol mixed solution. Their characteristics were identified by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), specific surface area (BET), Fourier transform infrared spectroscopy (FTIR) ...

  16. The Effect of Calcination Temperature on the Performance of TiO2 Aggregates-based Dye Solar Cells (DSCs)

    International Nuclear Information System (INIS)

    Siti Nur Azella Zaine; Norani Muti Mohamed; Mohamad Azmi Bustam

    2011-01-01

    In this paper, the effect of calcination temperature on the physicochemical properties of synthesized TiO 2 aggregates and their influence on overall light conversion efficiency of dye solar cell (DSc) were investigated. Samples of TiO 2 aggregates (mean size of 0.45 μm) composing of nano crystallites (10-40 nm) were synthesized through hydrolysis of dilute titanium alkoxide in ethanol. Phase and microstructure of the TiO 2 obtained have been characterized using FESEM, XRD and UV-Vis spectroscopy. I-V characterization shows that TiO 2 aggregates based DSC demonstrated better performance compared to nanoparticles (P-25)-based DSC. The optimum calcination temperature was found to be about 500 degree Celsius with efficiency of 4.456 %, which is 30 % increment compared to P-25-based DSC under the same condition. (author)

  17. Glycine assisted synthesis of flower-like TiO 2 hierarchical spheres and its application in photocatalysis

    KAUST Repository

    Tao, Yugui; Xu, Yanqiu; Pan, Jun; Gu, Hao; Qin, Changyun; Zhou, Peng

    2012-01-01

    Flower-like anatase TiO 2 hierarchical spheres assembled by nanosheets were synthesized by glycine assistant via a simple hydrothermal approach and after-annealing process. These flower-like spheres are about 2 μm in diameter with sheet thickness about 20 nm. Results showed reaction time, temperature, solution pH and glycine dosage all played an important role in control of shape and size of the as-synthesized TiO 2 nanocrystals. The photocatalytic activity of this nano-TiO 2 was evaluated by the photocatalytic oxidation decomposition of methyl orange under sunlight illumination in the presence of hydrogen peroxide (H 2O 2). The photocatalytic activity of the obtained TiO 2 was higher than that of commercial TiO 2. © 2012 Elsevier B.V.

  18. Glycine assisted synthesis of flower-like TiO 2 hierarchical spheres and its application in photocatalysis

    KAUST Repository

    Tao, Yugui

    2012-11-01

    Flower-like anatase TiO 2 hierarchical spheres assembled by nanosheets were synthesized by glycine assistant via a simple hydrothermal approach and after-annealing process. These flower-like spheres are about 2 μm in diameter with sheet thickness about 20 nm. Results showed reaction time, temperature, solution pH and glycine dosage all played an important role in control of shape and size of the as-synthesized TiO 2 nanocrystals. The photocatalytic activity of this nano-TiO 2 was evaluated by the photocatalytic oxidation decomposition of methyl orange under sunlight illumination in the presence of hydrogen peroxide (H 2O 2). The photocatalytic activity of the obtained TiO 2 was higher than that of commercial TiO 2. © 2012 Elsevier B.V.

  19. Facile synthesis and enhanced visible light photocatalytic activity of N and Zr co-doped TiO2 nanostructures from nanotubular titanic acid precursors

    Science.gov (United States)

    Zhang, Min; Yu, Xinluan; Lu, Dandan; Yang, Jianjun

    2013-12-01

    Zr/N co-doped TiO2 nanostructures were successfully synthesized using nanotubular titanic acid (NTA) as precursors by a facile wet chemical route and subsequent calcination. These Zr/N-doped TiO2 nanostructures made by NTA precursors show significantly enhanced visible light absorption and much higher photocatalytic performance than the Zr/N-doped P25 TiO2 nanoparticles. Impacts of Zr/N co-doping on the morphologies, optical properties, and photocatalytic activities of the NTA precursor-based TiO2 were thoroughly investigated. The origin of the enhanced visible light photocatalytic activity is discussed in detail.

  20. Synthesis, characterization, and analysis of enhanced photocatalytic activity of Zr-doped TiO2 nanostructured powders under UV light

    Science.gov (United States)

    Sekhar, M. Chandra; Purusottam Reddy, B.; Mallikarjuna, K.; Shanmugam, Gnanendra; Ahn, Chang-Hoi; Park, Si-Hyun

    2018-01-01

    Zr-doped and pure TiO2 nanoparticles (NPs) were synthesized using a simple inexpensive sol-gel method. X-ray powder diffractometry and Fourier transform infrared spectrometry revealed the presence of anatase-phase TiO2 NPs. Scanning electron microscopy and transmission electron microscopy revealed that the average nanocrystalline size of approximately 15 nm. The photocatalytic activities of these materials were evaluated using Rhodamine B (Rh B) as an organic contaminant. The photocatalytic activity of pure and Zr-doped TiO2 NPs (with at% 4, 8, 12 and 16) was measured in terms of the degradation of Rh B under UV light. The antibacterial activities of pure and Zr-doped (with 8 at%) TiO2 NPs were evaluated against Bacillus subtillis, Escherichia coli, and Pseudomonas aeruginosa. A maximum inhibition zone (19 mm) was observed for pure TiO2 NPs, against Bacillus subtillis and Pseudomonas aeruginosa, while Zr-doped TiO2 (8 at%) exhibited a lesser inhibition zone (18 mm) against the same Bacillus subtillis and Pseudomonas aeruginosa (18 mm). However, Zr-doped TiO2 (8 at%) NPs exhibited a greater inhibition zone against Escherichia coli (17 mm), while the activity of pure TiO2 NPs against Escherichia coli (15 mm) was retarded. Thus, pure TiO2 NPs and Zr-doped TiO2 (8 at%) NPs have competent activities and can be used as antibacterial agents against different bacteria.

  1. Solar photocatalytic activity of TiO2 modified with WO3 on the degradation of an organophosphorus pesticide

    International Nuclear Information System (INIS)

    Ramos-Delgado, N.A.; Gracia-Pinilla, M.A.; Maya-Treviño, L.; Hinojosa-Reyes, L.; Guzman-Mar, J.L.; Hernández-Ramírez, A.

    2013-01-01

    Highlights: • TiO 2 and WO 3 /TiO 2 (2 and 5%) were tested in the photocatalytic malathion degradation. • The use of solar radiation in the photocatalytic degradation process was evaluated. • Modified catalyst showed greater photocatalytic activity than pure TiO 2 . • The mineralization rate was improved when WO 3 content on TiO 2 was 2%. -- Abstract: In this study, the solar photocatalytic activity (SPA) of WO 3 /TiO 2 photocatalysts synthesized by the sol–gel method with two different percentages of WO 3 (2 and 5%wt) was evaluated using malathion as a model contaminant. For comparative purpose bare TiO 2 was also prepared by sol–gel process. The powders were characterized by X-ray diffraction (XRD), Raman spectroscopy, diffuse reflectance UV–vis spectroscopy (DRUV–vis), specific surface area by the BET method (SSA BET ), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and scanning transmission electron microscopy with a high annular angle dark field detector (STEM-HAADF). The XRD, Raman, HRTEM and STEM-HAADF analyses indicated that WO 3 was present as a monoclinic crystalline phase with nanometric cluster sizes (1.1 ± 0.1 nm for 2% WO 3 /TiO 2 and 1.35 ± 0.3 nm for 5% WO 3 /TiO 2 ) and uniformly dispersed on the surface of TiO 2 . The particle size of the materials was 19.4 ± 3.3 nm and 25.6 ± 3 nm for 2% and 5% WO 3 /TiO 2 , respectively. The SPA was evaluated on the degradation of commercial malathion pesticide using natural solar light. The 2% WO 3 /TiO 2 photocatalyst exhibited the best photocatalytic activity achieving 76% of total organic carbon (TOC) abatement after 300 min compared to the 5% WO 3 /TiO 2 and bare TiO 2 photocatalysts, which achieved 28 and 47% mineralization, respectively. Finally, experiments were performed to assess 2% WO 3 /TiO 2 catalyst activity on repeated uses; after several successive cycles its photocatalytic activity was retained showing long-term stability

  2. Nanostructured TiO2 Doped with Nb as a Novel Support for PEMFC

    Directory of Open Access Journals (Sweden)

    Edgar Valenzuela

    2013-01-01

    Full Text Available Nowadays, one of the major issues of the PEMFC concerns the durability. Historically, carbon has been used as a catalyst support in PEMFC; nevertheless, under the environmental conditions of the cell, the carbon is oxidized, leaving the catalyst unsupported. In order to increase the stability and durability of the catalyst in the PEMFC, a novel nanostructured metallic oxide support is proposed. In this work, TiO2 was doped with Nb to obtain a material that combines chemical stability, high surface area, and an adequate electronic conductivity in order to be a successful catalyst support candidate for long-term PEMFC applications. The TiO2-Nb nanostructured catalyst support was physically and electrochemically characterized. According to the results, the TiO2-Nb offers high surface area and good particle dispersion; also, the electrochemical activity and stability of the support were evaluated under high potential conditions, where the TiO2-Nb proved to be much more stable than carbon.

  3. Mo-doped Gray Anatase TiO2: Lattice Expansion for Enhanced Sodium Storage

    International Nuclear Information System (INIS)

    Liao, Hanxiao; Xie, Lingling; Zhang, Yan; Qiu, Xiaoqing; Li, Simin; Huang, Zhaodong; Hou, Hongshuai; Ji, Xiaobo

    2016-01-01

    Gray-colored Mo 6+ -doped anatase TiO 2 is prepared uniformly with particle size of 10–20 nm, and is firstly employed as anode material in sodium-ion batteries (SIBs), presenting excellent electrochemical performances. It delivered reversible specific capacities of 231.8 mAh g −1 at 0.1 C (33.5 mA g −1 ) after 100 cycles and 108.3 mAh g −1 at 5 C (1.68 A g −1 ), comparing to 170.5 mAh g −1 at 0.1 C and only 41.7 mAh g −1 at 5C for the bare TiO 2 . The improved electrochemical performances might be beneficial from the doping of Mo 6+ , which can effectively enhance the conductivity of TiO 2 resulting from induced conduction band electrons, interstitial oxygen defects and vacancies. In addition, the doping can also lead to the lattice expansion, which can facilitate the diffusion of Na + . In combination with natural abundance and environmental benignity, Mo 6+ -doped TiO 2 can be expected to be utilized as an anode material for enhanced sodium storage.

  4. Enhanced Photocatalytic Activity of La3+-Doped TiO2 Nanotubes with Full Wave-Band Absorption

    Science.gov (United States)

    Xia, Minghao; Huang, Lingling; Zhang, Yubo; Wang, Yongqian

    2018-06-01

    TiO2 nanotubes doped with La3+ were synthesized by anodic oxidation method and the photocatalytic activity was detected by photodegrading methylene blue. As-prepared samples improved the absorption of both ultraviolet light and visible light and have a great enhancement on the photocatalytic activity while contrasting with the pristine TiO2 nanotubes. A tentative mechanism for the enhancement of photocatalytic activity with full wave-band absorption is proposed.

  5. Interface role in the enhanced photocatalytic activity of TiO2-Na0.9Mg0.45Ti3.55O8 nanoheterojunction

    Directory of Open Access Journals (Sweden)

    Ze-Qing Guo

    2017-02-01

    Full Text Available TiO2-Na0.9Mg0.45Ti3.55O8 (TiO2-NMTO nanocomposites were synthesized via a simple hydrothermal method. TiO2 nanoparticles were loaded on NMTO nanosheets with well matched lattices. The TiO2-NMTO nanoheterojunctions enjoyed high photodegradative ability for a RhB pollutant. The photoinduced electron-hole pairs were separated effectively by the TiO2-NMTO nanoheterojunctions, which were directly observed by surface potential measurements with a scanning Kelvin probe microscopy. The photogenerated electrons accumulate at interface due to the high density of interface states, and holes remain TiO2 and NMTO particles, other than they migrate from one part to another in heterojunctions by comparing the surface potentials under illumination with different wavelengths.

  6. Synthesis and photocatalytic activity of TiO2/conjugated polymer complex nanoparticles

    Institute of Scientific and Technical Information of China (English)

    Shi Xiong Min; Fang Wang; Lei Feng; Yong Chun Tong; Zi Rong Yang

    2008-01-01

    A photocatalyst of nanometer TiO2/conjugated polymer complex was successfully synthesized and characterized by spectroscopic methods and photocatalytic experiments. The complex photocatalyst could be activated by absorbing both ultraviolet and visible light (λ=190-800nm). Methylene blue (MB) could be degraded more efficiently on the complex photocatalyst than on the TiO2 under natural light. The conjugated polymer played a promoting role in the photocatalytic degradation of MB. The calcination temperature had an important effect in degradation of dye and could be summarized as 260℃>300℃>340℃>220℃>180℃.

  7. Functionalized TiO2 nanoparticle containing isocyanate groups

    International Nuclear Information System (INIS)

    Ou, Baoli; Li, Duxin; Liu, Qingquan; Zhou, Zhihua; Liao, Bo

    2012-01-01

    Functionalized TiO 2 nanoparticle containing isocyanate groups can extend the TiO 2 nanoparticle chemistry, and may promote their many potential applications such as in polymer composites and coatings. This paper describes a facile method to prepare functionalized TiO 2 nanoparticle with highly reactive isocyanate groups on its surface, via the reaction between toluene-2, 4-diisocyanate (TDI) and hydroxyl on TiO 2 nanoparticle surface. The main effect factors on the reaction of TiO 2 with TDI were studied by determining the reaction extent of hydroxyl groups on TiO 2 surface. Fourier-transformed infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) confirmed that reactive isocyanate groups were covalently attached to the TiO 2 nanoparticle surface. The dispersion of the TDI-functionalized TiO 2 nanoparticle was studied by transmission electron microscopy (TEM). Owing to the TDI molecules covalently bonded on TiO 2 nanoparticle surface, it was established that the TiO 2 nanoparticle can be uniformly dispersed in toluene, thus indicating that this functionalization method can prevent TiO 2 nanoparticle from agglomerating. -- Highlights: ► TiO 2 nanoparticle was functionalized with toluene-2, 4-diisocyanate. ► Functionalized TiO 2 nanoparticle can be uniformly dispersed in xylene. ► Compatibility of TiO 2 nanoparticle and organic solvent is significantly improved. ► TiO 2 containing isocyanate groups can extend the TiO 2 nanoparticle chemistry.

  8. Controllable preparation of TiO2 nanowire arrays on titanium mesh for flexible dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Liu, Wenwu; Lu, Hui; Zhang, Mei; Guo, Min

    2015-01-01

    Graphical abstract: TiO 2 nanowire arrays with controlled morphology and density have been synthesized on Ti mesh substrates by hydrothermal approach for flexible dye-sensitized solar cells which showed well photovoltaic efficiency of 3.42%. - Highlights: • Flexible titanium mesh was first used for hydrothermal preparation of TiO 2 NWAs. • The formation mechanism of the TiO 2 nanostructures was discussed. • The density, average diameter, and morphology of TiO 2 NWAs can be controlled. • The effects of the sensitization temperature and time on the properties were studied. - Abstract: TiO 2 nanowire arrays (NWAs) with an average diameter of 80 nm have been successfully synthesized on titanium (Ti) mesh substrates via hydrothermal method. The effects of preparing conditions such as concentration of NaOH solution, reaction time, and hydrothermal temperature on the growth of TiO 2 nanoarrays and its related photovoltaic properties were systematically investigated by scanning electron microscopy, X-ray diffraction, and photovoltaic properties test. The growth mechanism of the Ti mesh-supported TiO 2 nanostructures was discussed in detail. Moreover, a parametric study was performed to determine the optimized temperature and time of the dye sensitized process for the flexible dye-sensitized solar cell (DSSC). It is demonstrated that hydrothermal parameters had obvious influence on the morphology and growth density of the as-prepared TiO 2 nanoarrays. In addition, the performance of the flexible DSSC depended strongly on the sensitization temperature and time. By utilizing Ti mesh-supported TiO 2 NWAs (with a length of about 14 μm) as a photoanode, the flexible DSSC with a short circuit current density of 10.49 mA cm −2 , an open-circuit voltage of 0.69 V, and an overall power conversion efficiency of 3.42% was achieved

  9. Recovery of hexavalent chromium from water using photoactive TiO2-montmorillonite under sunlight

    Directory of Open Access Journals (Sweden)

    Ridha Djellabi

    2016-04-01

    Full Text Available Hexavalent chromium was removed from water under sunlight using a synthesized TiO2-montmorillonite (TiO2-M employing tartaric acid as a hole scavenger. Cr(VI species was then reduced to Cr(III species by electrons arising from TiO2 particles. After that, the produced Cr(III species  was transferred to montmorillonite  due to electrostatic attractions leading to  set free TiO2 particles for a further Cr(VI species reduction. Furthermore, produced Cr(III, after Cr(VI reduction, does not  penetrate into the solution. The results indicate that no dark adsorption of Cr(VI species on TiO2-M is present, however, the reduction of Cr(VI species under sunlight increased strongly as a function of tartaric acid concentration up to 60 ppm, for which the extent of reduction is maximum within 3 h. On the other hand, the reduction extent of Cr(VI species is maximum with an initial concentration of Cr(VI species lower than 30 ppm by the use of 0.2 g/L of TiO2-M. Nevertheless, the increase of the Cr(VI initial concentration led to increase the amount of Cr(VI species reduced (capacity of reduction until a Cr(VI concentration of 75 and 100 ppm, for which  it remained constant at around 221 mg/g. For comparison, the increase of Cr(VI species concentration in the case of the commercial TiO2 P25 under the same conditions exhibited its deactivation when the reduced amount decreased from 198.1 to 157.6 mg/g as the concentration increased from 75 to 100 ppm.

  10. Mesoporous TiO2 Micro-Nanometer Composite Structure: Synthesis, Optoelectric Properties, and Photocatalytic Selectivity

    Directory of Open Access Journals (Sweden)

    Kun Liu

    2012-01-01

    Full Text Available Mesoporous anatase TiO2 micro-nanometer composite structure was synthesized by solvothermal method at 180°C, followed by calcination at 400°C for 2 h. The as-prepared TiO2 was characterized by X-ray diffraction (XRD, scanning electron microscope (SEM, transmission electron microscope (TEM, and Fourier transform infrared spectrum (FT-IR. The specific surface area and pore size distribution were obtained from N2 adsorption-desorption isotherm, and the optoelectric property of the mesoporous TiO2 was studied by UV-Vis absorption spectrum and surface photovoltage spectra (SPS. The photocatalytic activity was evaluated by photodegradation of sole rhodamine B (RhB and sole phenol aqueous solutions under simulated sunlight irradiation and compared with that of Degussa P-25 (P25 under the same conditions. The photodegradation preference of this mesoporous TiO2 was also investigated for an RhB-phenol mixed solution. The results show that the TiO2 composite structure consists of microspheres (∼0.5–2 μm in diameter and irregular aggregates (several hundred nanometers with rough surfaces and the average primary particle size is 10.2 nm. The photodegradation activities of this mesoporous TiO2 on both RhB and phenol solutions are higher than those of P25. Moreover, this as-prepared TiO2 exhibits photodegradation preference on RhB in the RhB-phenol mixture solution.

  11. Quantum Dot Sensitized Solar Cells Based on TiO2/AgInS2

    Science.gov (United States)

    Pawar, Sachin A.; Jeong, Jae Pil; Patil, Dipali S.; More, Vivek M.; Lee, Rochelle S.; Shin, Jae Cheol; Choi, Won Jun

    2018-05-01

    Quantum dot heterojunctions with type-II band alignment can efficiently separate photogenerated electron-hole pairs and, hence, are useful for solar cell studies. In this study, a quantum dot sensitized solar cell (QDSSC) made of TiO2/AgInS2 is achieved to boost the photoconversion efficiency for the TiO2-based system by varying the AgInS2 layer's thickness. The TiO2 nanorods array film is prepared by using a simple hydrothermal technique. The formation of a AgInS2 QD-sensitized TiO2-nanorod photoelectrode is carried out by successive ionic layer adsorption and reaction (SILAR) technique. The effect of the QD layer on the performance of the solar cell is studied by varying the SILAR cycles of the QD coating. The synthesized electrode materials are characterized by using X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, high resolution transmission electron microscopy and solar cell performances. The results indicate that the nanocrystals have effectively covered the outer surfaces of the TiO2 nanorods. The interfacial structure of quantum dots (QDs)/TiO2 is also investigated, and the growth interface is verified. A careful comparison between TiO2/AgInS2 sensitized cells reveals that the trasfer of electrons and hole proceeds efficiently, the recombination is suppressed for the optimum thickness of the QD layer and light from the entire visible spectrum is utilised. Under AM 1.5G illumination, a high photocurrent of 1.36 mAcm-2 with an improved power conversion efficiency of 0.48% is obtained. The solar cell properties of our photoanodes suggest that the TiO2 nanorod array films co-sensitized by AgInS2 nanoclusters have potential applications in solar cells.

  12. Enhanced photocatalytic degradation of dyes under sunlight using biocompatible TiO2 nanoparticles

    Science.gov (United States)

    Bharati, B.; Sonkar, A. K.; Singh, N.; Dash, D.; Rath, Chandana

    2017-08-01

    As TiO2 is one of the most popular photocatalysts, we have studied here the photocatalytic degradation of the most common dyestuffs like rhodamine B (RhB), congo red (CR) and methylene blue (MB), which mainly come from the textile and photographic industries using nanoparticles of TiO2. Nanoparticles of TiO2 synthesized through a simple and cost effective sol-gel technique crystallizes in the anatase phase, showing a band gap less than that of bulk value. Particles consisting of coherently scattered domains of size 33 nm are found to be agglomerated and polycrystalline in nature. While the degradation rates of MB, CR and RhB after irradiating with a renewable source of energy, i.e. sunlight, show 100% degradation, TiO2 irradiated with UV light of 4.8 eV shows a much slower degradation rate. To use the waste water after photocatalysis, we examine further the biocompatibile nature of the TiO2 nanoparticles by platelet interaction activity, hemolysis effect and MTT assay. It is worth mentioning here that TiO2 nanoparticles are found to be highly hemocompatible, show no platelet aggregation, and the level of intracellular ROS in human platelets does not show significant change in ROS level. We conclude that TiO2 nanoparticles constitute an excellent photocatalyst and biocompatible material, and that after photocatalytic degradation of dye effluents obtained from textile industries, purified water can be used in agriculture and domestic sectors.

  13. Hierarchical carambola-like Li4Ti5O12-TiO2 composites as advanced anode materials for lithium-ion batteries

    International Nuclear Information System (INIS)

    Zhang, Yu; Zhang, Yun; Huang, Ling; Zhou, Zhongfu; Wang, Jingfeng; Liu, Heng; Wu, Hao

    2016-01-01

    Hierarchically structured Li 4 Ti 5 O 12 -TiO 2 (LTO-TiO 2 ) composites are synthesized using a facile hydrothermal approach upon reaction time control. With control over the time of hydrothermal reaction at 18 h, a hierarchical dual-phase LTO-TiO 2 composite with appropriate amount of anatase TiO 2 can be obtained, and it possesses a uniform carambola-like framework assembled by numerous ultrathin nanosheets, which enable a relatively large specific surface area, along with abundant interlayer channels to favor electrolyte penetration. When used as anode materials for lithium-ion batteries, such carambola-like LTO-TiO 2 composite exhibits remarkably improved capacity, high-rate capability, and cycling stability over other LTO-TiO 2 samples, which are synthesized at different time of hydrothermal reaction. Specifically, it deliveries a discharge capacity as high as 115.1 and 91.2 mAh g −1 at a very high current rate of 20 and 40C, respectively, while a stable reversible capacity of 171.7 mAh g −1 can be retained after 200 charge-discharge cycles at 1C, corresponding to 88.6% capacity retention. The excellent electrochemical performances benefit from the unique hierarchical carambola-like structure together with the mutually complementary intrinsic advantages between LTO and TiO 2 . The robust and porous nanosheets-assembled LTO-TiO 2 framework not only offers a shorter transport pathway for electron and Li-ion migration within this composite material, but also is able to alleviate the structure distortion during the fast Li-ion insertion/extraction process. The work described here shows that the hierarchical carambola-like LTO-TiO 2 composite is a promising anode material for high-power and long-life lithium-ion batteries.

  14. Instability of Hydrogenated TiO2

    Energy Technology Data Exchange (ETDEWEB)

    Nandasiri, Manjula I.; Shutthanandan, V.; Manandhar, Sandeep; Schwarz, Ashleigh M.; Oxenford, Lucas S.; Kennedy, John V.; Thevuthasan, Suntharampillai; Henderson, Michael A.

    2015-11-06

    Hydrogenated TiO2 (H-TiO2) is toted as a viable visible light photocatalyst. We report a systematic study on the thermal stability of H-implanted TiO2 using X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA). Protons (40 keV) implanted at a ~2 atom % level within a ~120 nm wide profile of rutile TiO2(110) were situated ~300 nm below the surface. NRA revealed that this H-profile broadened preferentially toward the surface after annealing at 373 K, dissipated out of the crystal into vacuum at 473 K, and was absent within the beam sampling depth (~800 nm) at 523 K. Photoemission showed that the surface was reduced in concert with these changes. Similar anneals had no effect on pristine TiO2(110). The facile bulk diffusivity of H in rutile, as well as its activity toward interfacial reduction, significantly limits the utilization of H-TiO2 as a photocatalyst. This work was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle. The research was performed using the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory.

  15. Preparation of flexible TiO2 photoelectrodes for dye-sensitized solar cells

    Science.gov (United States)

    Li, Wen-Ren; Wang, Hsiu-Hsuan; Lin, Chia-Feng; Su, Chaochin

    2014-09-01

    Dye-sensitized solar cells (DSSCs) based on nanocrystalline TiO2 photoelectrodes on indium tin oxide (ITO) coated polymer substrates have drawn great attention due to its lightweight, flexibility and advantages in commercial applications. However, the thermal instability of polymer substrates limits the process temperature to below 150 °C. In order to assure high and firm interparticle connection between TiO2 nanocrystals (TiO2-NC) and polymer substrates, the post-treatment of flexible TiO2 photoelectrodes (F-TiO2-PE) by mechanical compression was employed. In this work, Degussa P25 TiO2-NC was mixed with tert-butyl alcohol and DI-water to form TiO2 paste. F-TiO2-PE was then prepared by coating the TiO2 paste onto ITO coated polyethylene terephthalate (PET) substrate using doctor blade followed by low temperature sintering at 120 °C for 2 hours. To study the effect of mechanical compression, we applied 50 and 100 kg/cm2 pressure on TiO2/PET to complete the fabrication of F-TiO2-PE. The surface morphology of F-TiO2-PE was characterized using scanning electron microscopy. The resultant F-TiO2-PE sample exhibited a smooth, crack-free structure indicating the great improvement in the interparticle connection of TiO2-NC. Increase of compression pressure could lead to the increase of DSSC photoconversion efficiency. The best photoconversion efficiency of 4.19 % (open circuit voltage (Voc) = 0.79 V, short-circuit photocurrent density (Jsc) = 7.75 mA/cm2, fill factor (FF) = 0.68) was obtained for the F-TiO2-PE device, which showed great enhancement compared with the F-TiO2-PE cell without compression treatment. The effect of compression in DSSC performance was vindicated by the electrochemical impedance spectroscopy measurement.

  16. A chemical route to room-temperature synthesis of nanocrystalline TiO2 thin films

    International Nuclear Information System (INIS)

    Pathan, Habib M.; Kim, Woo Young; Jung, Kwang-Deog; Joo, Oh-Shim

    2005-01-01

    A lot of methods are developed for the deposition of TiO 2 thin films; however, in each of these methods as-deposited films are amorphous and need further heat treatment at high temperature. In the present article, a chemical bath deposition (CBD) method was used for the preparation of TiO 2 thin films. We investigated nanocrystalline TiO 2 thin films using CBD at room temperature onto glass and ITO coated glass substrate. The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM) techniques. The chemically synthesized films were nanocrystalline and composed of crystal grains of 2-3 nm

  17. Photocatalytic activity of TiO2 doped with boron and vanadium

    International Nuclear Information System (INIS)

    Bettinelli, M.; Dallacasa, V.; Falcomer, D.; Fornasiero, P.; Gombac, V.; Montini, T.; Romano, L.; Speghini, A.

    2007-01-01

    Boron (B)- and vanadium (V)-doped TiO 2 photocatalysts were synthesized using modified sol-gel reaction processes and characterized by X-ray diffraction (XRD), Raman spectroscopy and N 2 physisorption (BET). The photocatalytic activities were evaluated by monitoring the degradation of methylene blue (MB). The results showed that the materials possess high surface area. The addition of B favored the transformation of anatase to rutile, while in the presence of V, anatase was the only phase detected. The MB degradation on V-doped TiO 2 was significantly affected by the preparation method. In fact while the presence of V in the bulk did not influence strongly the photoreactivity under visible irradiation, an increase of surface V doping lead to improved photodegradation of MB. The degradation of MB dye indicated that the photocatalytic activities of TiO 2 increased as the boron doping increased, with high conversion efficiency for 9 mol% B doping

  18. Temperature dependence of gas sensing behaviour of TiO2 doped PANI composite thin films

    Science.gov (United States)

    Srivastava, Subodh; Sharma, S. S.; Sharma, Preetam; Sharma, Vinay; Rajura, Rajveer Singh; Singh, M.; Vijay, Y. K.

    2014-04-01

    In the present work we have reported the effect of temperature on the gas sensing properties of TiO2 doped PANI composite thin film based chemiresistor type gas sensors for hydrogen gas sensing application. PANI and TiO2 doped PANI composite were synthesized by in situ chemical oxidative polymerization of aniline at low temperature. The electrical properties of these composite thin films were characterized by I-V measurements as function of temperature. The I-V measurement revealed that conductivity of composite thin films increased as the temperature increased. The changes in resistance of the composite thin film sensor were utilized for detection of hydrogen gas. It was observed that at room temperature TiO2 doped PANI composite sensor shows higher response value and showed unstable behavior as the temperature increased. The surface morphology of these composite thin films has also been characterized by scanning electron microscopy (SEM) measurement.

  19. Photooxidative desulfurization for diesel using Fe / N - TiO2 photocatalyst

    Science.gov (United States)

    Khan, Muhammad Saqib; Kait, Chong Fai; Mutalib, Mohd Ibrahim Abdul

    2014-10-01

    A series of N - TiO2 with different mol% N was synthesized via sol-gel method and characterized using thermal gravimetric analyzer and raman spectroscopy. 0.2 wt% Fe was incorporated onto the calcined (200°C) N - TiO2 followed by calcination at 200°C, 250°C and 300°C. Photooxidative desulfurization was conducted in the presence of 0.2wt% Fe / N - TiO2 with different mol% N with and without oxidant (H2O2). Oxidative desulfurization was only achieved when H2O2 was used while without H2O2 no major effect on the sulfur removal. 0.2Fe -30N - H2O2 photocatalysts showed best performance at all calcination temperatures as compared to other mol% N - H2O2 photocatalysts. 16.45% sulfur removal was achieved using photocatalysts calcined at 300 °C.

  20. Synthesis and Photocatalytic Activity of Mo-Doped TiO2 Nanoparticles

    Directory of Open Access Journals (Sweden)

    Ji-guo Huang

    2015-01-01

    Full Text Available The undoped and Mo-doped TiO2 nanoparticles were synthesized by sol-gel method. The as-prepared samples were characterized by X-ray diffraction (XRD, diffuse reflectance UV-visible absorption spectra (UV-vis DRS, X-ray photoelectron spectra (XPS, and transmission electron microscopy (TEM. The photocatalytic activity was evaluated by photocatalytic degradation of methylene blue under irradiation of a 500 W xenon lamp and natural solar light outdoor. Effects of calcination temperatures and Mo doping amounts on crystal phase, crystallite size, lattice distortion, and optical properties were investigated. The results showed that most of Mo6+ took the place of Ti4+ in the crystal lattice of TiO2, which inhibited the growth of crystallite size, suppressed the transformation from anatase to rutile, and led to lattice distortion of TiO2. Mo doping narrowed the band gap (from 3.05 eV of TiO2 to 2.73 eV of TiMo0.02O and efficiently increased the optical absorption in visible region. Mo doping was shown to be an efficient method for degradation of methylene blue under visible light, especially under solar light. When the calcination temperature was 550°C and the Mo doping amount was 2.0%, the Mo-doped TiO2 sample exhibited the highest photocatalytic activity.

  1. Highly stable colloidal TiO2 nanocrystals with strong violet-blue emission

    International Nuclear Information System (INIS)

    Ghamsari, Morteza Sasani; Gaeeni, Mohammad Reza; Han, Wooje; Park, Hyung-Ho

    2016-01-01

    Improved sol–gel method has been applied to prepare highly stable colloidal TiO 2 nanocrystals. The synthesized titania nanocrystals exhibit strong emission in the violet-blue wavelength region. Very long evolution time was obtained by preventing the sol to gel conversion with reflux process. FTIR, XRD, UV–vis absorption, photoluminescence and high resolution transmission electron microscope (HRTEM) were used to study the optical properties, crystalline phase, morphology, shape and size of prepared TiO 2 colloidal nanocrystals. HRTEM showed that the diameter of TiO 2 colloidal nanocrystals is about 5 nm. Although the PL spectra show similar spectral features upon excitation wavelengths at 280, 300 and 350 nm, but their emission intensities are significantly different from each other. Photoluminescence quantum yield for TiO 2 colloidal nanocrystals is estimated to be 49% with 280 nm excitation wavelength which is in agreement and better than reported before. Obtained results confirm that the prepared colloidal TiO 2 sample has enough potential for optoelectronics applications.

  2. Enhanced Photocatalytic Activity of TiO2 Nanoparticles Supported on Electrically Polarized Hydroxyapatite.

    Science.gov (United States)

    Zhang, Xuefei; Yates, Matthew Z

    2018-05-23

    Fast recombination of photogenerated charge carriers in titanium dioxide (TiO 2 ) remains a challenging issue, limiting the photocatalytic activity. This study demonstrates increased photocatalytic performance of TiO 2 nanoparticles supported on electrically polarized hydroxyapatite (HA) films. Dense and thermally stable yttrium and fluorine co-doped HA films with giant internal polarization were synthesized as photocatalyst supports. TiO 2 nanoparticles deposited on the support were then used to catalyze the photochemical reduction of aqueous silver ions to produce silver nanoparticles. It was found that significantly more silver nanoparticles were produced on polarized HA supports than on depolarized HA supports. In addition, the photodegradation of methyl orange with TiO 2 nanoparticles on polarized HA supports was found to be much faster than with TiO 2 nanoparticles on depolarized HA supports. It is proposed that separation of photogenerated electrons and holes in TiO nanoparticles is promoted by the internal polarization of the HA support, and consequently, the recombination of charge carriers is mitigated. The results imply that materials with large internal polarization can be used in strategies for enhancing quantum efficiency of photocatalysts.

  3. Nitrogen and europium doped TiO2 anodized films with applications in photocatalysis

    International Nuclear Information System (INIS)

    Chi, Choong-Soo; Choi, Jinwook; Jeong, Yongsoo; Lee, Oh Yeon; Oh, Han-Jun

    2011-01-01

    Micro-arc oxidation method is a useful process for mesoporous titanium dioxide films. In order to improve the photocatalytic activity of the TiO 2 film, N-Eu co-doped titania catalyst was synthesized by micro-arc oxidation in the H 2 SO 4 /Eu(NO 3 ) 3 mixture solution. The specific surface area and the roughness of the anodic titania film fabricated in the H 2 SO 4 /Eu(NO 3 ) 3 electrolyte, were increased compared to that of the anodic TiO 2 film prepared in H 2 SO 4 solution. The absorbance response of N-Eu titania film shows a higher adsorption onset toward visible light region, and the incorporated N and Eu ions during anodization as a dopant in the anodic TiO 2 film significantly enhanced the photocatalytic activity for dye degradation. After dye decomposition test for 3 h, dye removal rates for the anodic TiO 2 film were 60.7% and 90.1% for the N-Eu doped titania film. The improvement of the photocatalytic activity was ascribed to the synergistic effects of the surface enlargement and the new electronic state of the TiO 2 band gap by N and Eu co-doping.

  4. Core–shell TiO2 microsphere with enhanced photocatalytic activity and improved lithium storage

    International Nuclear Information System (INIS)

    Guo, Hong; Tian, Dongxue; Liu, Lixiang; Wang, Yapeng; Guo, Yuan; Yang, Xiangjun

    2013-01-01

    Inorganic hollow core–shell spheres have attracted considerable interest due to their singular properties and wide range of potential applications. Herein a novel facile generic strategy of combining template assisted and solvothermal alcoholysis is employed to prepare core–void–shell anatase TiO 2 nanoparticle aggregates with an excellent photocatalytic activity, and enhanced lithium storage in large quantities. Amorphous carbon can be loaded on the TiO 2 nanoparticles uniformly under a suitably formulated ethanol/water system in the solvothermal alcoholysis process, and the subsequent calcination results of the formation of core–shell–shell anatase TiO 2 nanoparticle aggregates. The intrinsic core–void–shell nature as well as high porosity of the unique nanostructures contributes greatly to the superior photocatalytic activity and improved performance as anode materials for lithium ion batteries. - Graphical abstract: A novel strategy of combining template assisted and solvothermal alcoholysis is employed to prepare unique core–void–shell anatase TiO 2 nanoparticle aggregates with the superior photocatalytic activity and improved lithium storage. Highlights: ► TiO 2 mesospheres are synthesized by solvothermal alcoholysis. ► It is core–void–shell structure and the thickness of shell is estimated to 80 nm. ► It exhibits a remarkable photocatalytic activity and improved lithium storage

  5. Improving the Osteoblast Cell Adhesion on Electron Beam Controlled TiO2 Nanotubes

    Directory of Open Access Journals (Sweden)

    Sung Wook Yoon

    2014-01-01

    Full Text Available Here we investigate the osteogenesis and synostosis processes on the surface-modified TiO2 nanotubes via electron beam irradiation. The TiO2 nanotubes studied were synthesized by anodization process under different anodizing voltage. For the anodization voltage of 15, 20, and 25 V, TiO2 nanotubes with diameters of 59, 82, and 105 nm and length of 115, 276, and 310 nm were obtained, respectively. MC3T3-E1 osteoblast cell line was incubated on the TiO2 nanotubes to monitor the change in the cell adhesion before and after the electron beam irradiation. We observe that the electron beam irradiation affects the number of surviving osteoblast cells as well as the cultivation time. In particular, the high adhesion rate of 155% was obtained when the osteoblast cells were cultivated for 2 hours on the TiO2 nanotube, anodized under 20 V, and irradiated with 5,000 kGy of electron beam.

  6. Deliberate Design of TiO2 Nanostructures towards Superior Photovoltaic Cells.

    Science.gov (United States)

    Sun, Ziqi; Liao, Ting; Sheng, Liyuan; Kou, Liangzhi; Kim, Jung Ho; Dou, Shi Xue

    2016-08-01

    TiO2 nanostructures are being sought after as flexibly utilizable building blocks for the fabrication of the mesoporous thin-film photoelectrodes that are the heart of the third-generation photovoltaic devices, such as dye-sensitized solar cells (DSSCs), quantum-dot-sensitized solar cells (QDSSCs), and the recently promoted perovskite-type solar cells. Here, we report deliberate tailoring of TiO2 nanostructures for superior photovoltaic cells. Morphology engineering of TiO2 nanostructures is realized by designing synthetic protocols in which the precursor hydrolysis, crystal growth, and oligomer self-organization are precisely controlled. TiO2 nanostructures in forms varying from isolated nanocubes, nanorods, and cross-linked nanorods to complex hierarchical structures and shape-defined mesoporous micro-/nanostructures were successfully synthesized. The photoanodes made from the shape-defined mesoporous TiO2 microspheres and nanospindles presented superior performances, owing to the well-defined overall shapes and the inner ordered nanochannels, which allow not only a high amount of dye uptake, but also improved visible-light absorption. This study provides a new way to seek an optimal synthetic protocol to meet the required functionality of the nanomaterials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Photosensitization of TiO2 P25 with CdS Nanoparticles for Photocatalytic Applications

    Directory of Open Access Journals (Sweden)

    Trenczek-Zając A.

    2017-06-01

    Full Text Available A TiO2/CdS coupled system was prepared by mixing the TiO2 P25 with CdS synthesized by means of the precipitation method. It was found that the specific surface area (SSA of both components is extremely different and equals 49.5 for TiO2 and 145.4 m2·g−1 for CdS. The comparison of particle size distribution and images obtained by means of transmission electron microscopy (TEM showed agglomeration of nanocomposites. X-ray diffraction (XRD patterns suggest that CdS crystallizes in a mixture of cubic and hexagonal phases. Optical reflectance spectra revealed a gradual shift of the fundamental absorption edge towards longer wavelengths with increasing CdS molar fraction, which indicates an extension of the absorption spectrum of TiO2. The photocatalytic activity in UV and UV-vis was tested with the use of methyl orange (MO. The Langmuir–Hinshelwood model described well the photodegradation process of MO. The results showed that the photocatalytic behaviour of the TiO2/CdS mixture is significantly better than that of pure nanopowders.

  8. Flexible all-solid-state high-performance supercapacitor based on electrochemically synthesized carbon quantum dots/polypyrrole composite electrode

    International Nuclear Information System (INIS)

    Jian, Xuan; Yang, Hui-min; Li, Jia-gang; Zhang, Er-hui; Cao, Le-le; Liang, Zhen-hai

    2017-01-01

    Highlights: • Porous nanostructure carbon quantum dots/polypyrrole composite film was successfully synthesized by direct electrochemical method. • A flexible all-solid-state supercapacitor device was fabricated using the carbon quantum dots/polypyrrole composite electrode. • The flexible supercapacitor exhibits high specific capacitance, excellent reliability and long cycling life. - Abstract: Recently, carbon quantum dots (CQDs) as a new zero-dimensional carbon nanomaterial have become a focus in electrochemical energy storage. In this paper, flexible all-solid-state supercapacitors (ASSSs) were electrochemically synthesized by on-step co-deposition of appropriate amounts of pyrrole monomer and CQDs in aqueous solution. The different electrodeposition time plays an important role in controlling morphologies of stainless steel wire meshes (SSWM)-supported CQDs/PPy composite film. The morphologies and compositions of the obtained CQDs/PPy composite electrodes were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Raman spectrum and X-ray photoelectron spectroscopy (XPS). Furthermore, a novel flexible ASSS device was fabricated using CQDs/PPy composite as the electrode and separated by polyvinyl alcohol/LiCl gel electrolyte. Benefiting from superior electrochemical properties of CQDs and PPy, the as-prepared CQDs/PPy composite ASSSs exhibit outstanding electrochemical performance with the areal capacitance 315 mF cm −2 (corresponding to specific capacitance of 308 F g −1 ) at a current density of 0.2 mA cm −2 and long cycle life with 85.7% capacitance retention after 2 000 cycles.

  9. Ecotoxicity of TiO2 to Daphnia similis under irradiation

    International Nuclear Information System (INIS)

    Marcone, Glauciene P.S.; Oliveira, Ádria C.; Almeida, Gilberto; Umbuzeiro, Gisela A.; Jardim, Wilson F.

    2012-01-01

    Graphical abstract: EC50 (mg L −1 ) values to TiO 2 samples obtained in toxicity tests with Daphnia similis under different conditions of illumination (UV A and visible radiation) and in the dark (as standard protocols). P25: commercial sample containing 30% rutile and 70% anatase; M-S: synthesized sample containing 30% rutile and 70% anatase; Anatase-S: synthesized sample containing 100% anatase; Rutile-S: synthesized sample containing 100% rutile and P25*: commercial sample containing 100% rutile. Highlights: ► Some key physicochemical parameters of nano TiO 2 explain the toxicity observed. ► Under UV A radiation, TiO 2 becomes more toxic to D. similis. ► Toxicity tests of photoactive nano materials require photons as control parameter. - Abstract: Currently, there are a large number of products (sunscreen, pigments, cosmetics, plastics, toothpastes and photocatalysts) that use TiO 2 nanoparticles. Due to this large production, these nanoparticles can be released into the aquatic, terrestrial and aerial environments at relative high concentration. TiO 2 in natural water has the capacity to harm aquatic organisms such as the Daphnia (Cladocera) species, mainly because the photocatalytic properties of this semiconductor. However, very few toxicity tests of TiO 2 nanoparticles have been conducted under irradiation. The aim of this study was to evaluate anatase and rutile TiO 2 toxicity to Daphnia similis exploring their photocatalytic properties by incorporating UV A and visible radiation as a parameter in the assays. Anatase and rutile TiO 2 samples at the highest concentration tested (100 mg L −1 ) were not toxic to D. similis, neither in the dark nor under visible light conditions. The anatase form and a mixture of anatase and rutile, when illuminated by a UV A black light with a peak emission wavelength of 360 nm, presented photo-dependent EC50 values of 56.9–7.8 mg L −1 , which indicates a toxicity mechanism caused by ROS (reactive oxygen species

  10. Effect of preparation conditions on the characteristics and photocatalytic activity of TiO2/purified diatomite composite photocatalysts

    International Nuclear Information System (INIS)

    Sun, Zhiming; Hu, Zhibo; Yan, Yang; Zheng, Shuilin

    2014-01-01

    Highlights: • TiO 2 /purified diatomite composites were synthesized under different conditions. • The optimum preparation conditions of composites were obtained. • The obtained photocatalyst showed good photocatalytic activity. • The dispersity and grain size of loaded TiO 2 NPs are the critical factors. - Abstract: TiO 2 /purified diatomite composite materials were prepared through a modified hydrolysis-deposition method under low temperature using titanium tetrachloride as precursor combined with a calcination crystallization process. The microstructure and crystalline phases of the obtained composites prepared under different preparation conditions were characterized by high resolution scanning electron microscope (SEM) and X-ray diffraction (XRD), respectively. The photocatalytic performance of TiO 2 /purified diatomite composites was evaluated by Rhodamine B as the target pollutant under UV irradiation, and the optimum preparation conditions of composites were obtained. The TiO 2 crystal form in composites prepared under optimum conditions was anatase, the grain size of which was 34.12 nm. The relationships between structure and property of composite materials were analyzed and discussed. It is indicated that the TiO 2 nanoparticles uniformly dispersed on the surface of diatoms, and the photocatalytic performance of the composite materials was mainly determined by the dispersity and grain size of loaded TiO 2 nanoparticles

  11. Synergistic operation of photocatalytic degradation and Fenton process by magnetic Fe3O4 loaded TiO2

    Science.gov (United States)

    Sun, Qiong; Hong, Yong; Liu, Qiuhong; Dong, Lifeng

    2018-02-01

    The magnetic Fe3O4 loaded anatase TiO2 photocatalysts with different mass ratios were successfully synthesized by a one-step convenient calcining method. The morphology and structure analysis revealed that Fe3O4 was formed in TiO2 with very fine-grained particles. After a small amount of Fe3O4 loaded onto TiO2, the photocatalytic property enhanced obviously for the degradation of organic dye. Furthermore, the photo-Fenton-like catalysis of the iron-containing samples could also be induced after the addition of hydrogen peroxide. The apparent kinetic constant of the reaction that catalyzed by Fe-TiO2 was about 5.3 and 8.3 times of that catalyzed by TiO2 or Fe3O4 only, respectively, proving an effective synergistic contribution of the photocatalysis and Fenton reaction in the composite. Compared with Fe3O4 or free Fe3+ ions, only 13% of iron in TiO2 dissolved into acidic solution (25% for Fe3O4 and 100% for Fe3+) after the reaction, which confirmed the iron had been well immobilized onto TiO2. In addition, the extremely stable photocatalytic activity in cycling experiments proved the immobilized iron had been tightly attached onto TiO2, indicating the great potential of the catalyst for practical applications.

  12. Enhancement of the photocatalytic activity of TiO2 nanoparticles by surface-capping DBS groups

    International Nuclear Information System (INIS)

    Wang Baiqi; Jing Liqiang; Qu Yichun; Li Shudan; Jiang Baojiang; Yang Libin; Xin Baifu; Fu Honggang

    2006-01-01

    TiO 2 nanoparticles capped with sodium dodecylbenzenesulfonate (DBS) are synthesized by a sol-hydrothermal process using tetrabutyl titanate and DBS as raw materials. The effects of surface-capping DBS on the surface photovoltage spectroscopy (SPS), photoluminescence (PL) and photocatalytic performance of TiO 2 nanoparticles are principally investigated together with their relationships. The results show that the surface of TiO 2 nanoparticles can be well capped by DBS groups while the pH value and added DBS amount are controlled at 5.0 and 2% of TiO 2 mass weight, respectively, and the linkage between DBS groups and TiO 2 surfaces is mainly by means of quasi-sulphonate bond. The intensities of SPS and PL spectra of TiO 2 obviously decrease after DBS-capping, while the activity can greatly increase during the photocatalytic degradation of Rhodamine B (RhB) solution, which are mainly attributed to the electron-withdrawing character of the DBS groups. Moreover, the enhancement of photocatalytic activity of DBS-capped TiO 2 is also related to the increase in the capability for adsorbing RhB

  13. Development of high efficient visible light-driven N, S-codoped TiO2 nanowires photocatalysts

    International Nuclear Information System (INIS)

    Zhang, Yanlin; Liu, Peihong; Wu, Honghai

    2015-01-01

    Highlights: • A facile hydrothermal route to synthesize N, S-codoped TiO 2 nanowires. • The codoped TiO 2 nanowires have TiO 2 (B) and anatase phase. • The significant shift of the optical absorption edge toward the visible region. • The photocatalyst showed high photocatalytic activity for atrazine. - Abstract: One-dimensional (1D) nanowire material (especially nonmetal doped 1D nanowires) synthesized by a facile way is of great significance and greatly desired as it has higher charge carrier mobility and lower carrier recombination rate. N, S-codoped TiO 2 nanowires were synthesized using titanium sulfate as a precursor and isopropanol as a protective capping agent by a hydrothermal route. The obtained doped nanowires were characterized by XRD, SEM, HRTEM, SAED, XPS, BET and UV–vis absorption spectrum. The incorporation of N and S into TiO 2 NWs can lead to the expansion of its lattice and remarkably lower its electron-transfer resistance. Photocatalytic activity measurement showed that the N, S-codoped TiO 2 nanowires with high quantum efficiency revealed the best photocatalytic performance for atrazine degradation under visible light irradiation compared to N, S-codoped TiO 2 nanoparticles and S-doped TiO 2 nanowires, which was attributed to (i) the synergistic effect of N and S doping in narrowing the band gap, separating electron–hole pairs and increasing the photoinduced electrons, and (ii) extending the anatase-to-rutile transformation temperature above 600 °C

  14. TiO2-TiO2 composite resistive humidity sensor: ethanol crosssensitivity

    International Nuclear Information System (INIS)

    Ghalamboran, Milad; Saedi, Yasin

    2016-01-01

    The fabrication method and characterization results of a TiO 2 -TiO 2 composite bead used for humidity sensing along with its negative cross-sensitivity to ethanol vapor are reported. The bead shaped resistive sample sensors are fabricated by the drop-casting of a TiO 2 slurry on two Pt wire segments. The dried bead is pre-fired at 750°C and subsequently impregnated with a Ti-based sol. The sample is ready for characterization after a thermal annealing at 600°C in air. Structurally, the bead is a composite of the micron-sized TiO 2 crystallites embedded in a matrix of nanometric TiO 2 particle aggregates. The performance of the beads as resistive humidity sensors is recorded at room temperature in standard humidity level chambers. Results evince the wide dynamic range of the sensors fabricated in the low relative humidity range. While the sensor conductance is not sensitive to ethanol vapor in dry air, in humid air, sensor's responses are negatively affected by the contaminant. (paper)

  15. The Influence of TiO2 Nanoparticles on LaFeO3/TiO2 Nanocomposites for Reduction of Aqueous Organic Dyes

    International Nuclear Information System (INIS)

    Afifah, N.; Saleh, R.

    2016-01-01

    A series of Lanthanum ferrite (LaFeO3) nanoparticles over titanium dioxide (TiO2) were synthesized using sol-gel method at room temperature by varying the loading of LaFeO3 on TiO2. The magnetic properties of samples were measured using vibrating sample magnetometer and photosonocatalytic activity towards the degradation of methylene blue under light (UV or visible) and ultrasound irradiation was also evaluated. The morphology and structure of the samples were characterized by field emission scanning electron microscope, energy dispersive analysis and X-ray diffraction. Furthermore the optical properties were also characterized by UV-visible diffuse reflectance. The experimental results showed that the prepared perovskites had sphere-like shape and strong visible light absorption. LaFeO3 demonstrated ferromagnetic properties and the magnetization decreased with the incorporation of TiO2 in the samples. However, the incorporation of TiO2 increased the photosonocatalytic activity and extended the photoresponding to UV light. (paper)

  16. 1D TiO2 Nanostructures Prepared from Seeds Presenting Tailored TiO2 Crystalline Phases and Their Photocatalytic Activity for Escherichia coli in Water

    Directory of Open Access Journals (Sweden)

    Julieta Cabrera

    2018-01-01

    Full Text Available TiO2 nanotubes were synthesized by alkaline hydrothermal treatment of TiO2 nanoparticles with a controlled proportion of anatase and rutile. Tailoring of TiO2 phases was achieved by adjusting the pH and type of acid used in the hydrolysis of titanium isopropoxide (first step in the sol-gel synthesis. The anatase proportion in the precursor nanoparticles was in the 3–100% range. Tube-like nanostructures were obtained with an anatase percentage of 18 or higher while flake-like shapes were obtained when rutile was dominant in the seed. After annealing at 400°C for 2 h, a fraction of nanotubes was conserved in all the samples but, depending on the anatase/rutile ratio in the starting material, spherical and rod-shaped structures were also observed. The photocatalytic activity of 1D nanostructures was evaluated by measuring the deactivation of E. coli in stirred water in the dark and under UV-A/B irradiation. Results show that in addition to the bactericidal activity of TiO2 under UV-A illumination, under dark conditions, the decrease in bacteria viability is ascribed to mechanical stress due to stirring.

  17. Novel Ag@TiO2 nanocomposite synthesized by electrochemically active biofilm for nonenzymatic hydrogen peroxide sensor

    International Nuclear Information System (INIS)

    Khan, Mohammad Mansoob; Ansari, Sajid Ali; Lee, Jintae; Cho, Moo Hwan

    2013-01-01

    A novel nonenzymatic sensor for H 2 O 2 was developed based on an Ag@TiO 2 nanocomposite synthesized using a simple and cost effective approach with an electrochemically active biofilm. The optical, structural, morphological and electrochemical properties of the as-prepared Ag@TiO 2 nanocomposite were examined by UV–vis spectroscopy, X-ray diffraction, transmission electron microscopy and cyclic voltammetry (CV). The Ag@TiO 2 nanocomposite was fabricated on a glassy carbon electrode (GCE) and their electrochemical performance was analyzed by CV, differential pulse voltammetry and electrochemical impedance spectroscopy. The Ag@TiO 2 nanocomposite modified GCE (Ag@TiO 2 /GCE) displayed excellent performance towards H 2 O 2 sensing at − 0.73 V in the linear response range from 0.83 μM to 43.3 μM, within a detection limit and sensitivity of 0.83 μM and ∼ 65.2328 ± 0.01 μAμM −1 cm −2 , respectively. In addition, Ag@TiO 2 /GCE exhibited good operational reproducibility and long term stability. - Graphical abstract: Synthesis of Ag@TiO 2 nanocomposite by electrochemically active biofilm for H 2 O 2 sensing. - Highlights: • Electrochemically active biofilm (EAB) • EAB mediated synthesis of Ag@TiO 2 nanocomposite • Ag@TiO 2 nanocomposite modified glassy carbon electrode • Ag@TiO 2 /GCE for H 2 O 2 sensing • Nonenzymatic sensor for H 2 O 2

  18. TiO2 Nanotubes: Recent Advances in Synthesis and Gas Sensing Properties

    Directory of Open Access Journals (Sweden)

    Giorgio Sberveglieri

    2013-10-01

    Full Text Available Synthesis—particularly by electrochemical anodization-, growth mechanism and chemical sensing properties of pure, doped and mixed titania tubular arrays are reviewed. The first part deals on how anodization parameters affect the size, shape and morphology of titania nanotubes. In the second part fabrication of sensing devices based on titania nanotubes is presented, together with their most notable gas sensing performances. Doping largely improves conductivity and enhances gas sensing performances of TiO2 nanotubes

  19. Swift heavy ions induced surface modifications in Ag-polypyrrole composite films synthesized by an electrochemical route

    International Nuclear Information System (INIS)

    Kumar, Vijay; Ali, Yasir; Sharma, Kashma; Kumar, Vinod; Sonkawade, R.G.; Dhaliwal, A.S.; Swart, H.C.

    2014-01-01

    Highlights: • Two steps electrochemical synthesis for the fabrication of Ag-polypyrrole composite films. • Surface modifications by swift heavy ion beam. • SEM image shows the formation of craters and humps after irradiation. • Detailed structural analysis by Raman spectroscopy. - Abstract: The general aim of this work was to study the effects of swift heavy ions on the properties of electrochemically synthesized Ag-polypyrrole composite thin films. Initially, polypyrrole (PPy) films were electrochemically synthesized on indium tin oxide coated glass surfaces using a chronopotentiometery technique, at optimized process conditions. The prepared PPy films have functioned as working electrodes for the decoration of submicron Ag particles on the surface of the PPy films through a cyclicvoltammetry technique. Towards probing the effect of swift heavy ion irradiation on the structural and morphological properties, the composite films were subjected to a 40 MeV Li 3+ ion beam irradiation for various fluences (1 × 10 11 , 1 × 10 12 and 1 × 10 13 ions/cm 2 ). Comparative microstructural investigations were carried out after the different ion fluences using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy and micro-Raman spectroscopy techniques. Raman and SEM studies revealed that the structure of the films became disordered after irradiation. The SEM studies of irradiated composite films show significant changes in their surface morphologies. The surface was smoother at lower fluence but craters were observed at higher fluence

  20. Swift heavy ions induced surface modifications in Ag-polypyrrole composite films synthesized by an electrochemical route

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Vijay, E-mail: vijays_phy@rediffmail.com [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein ZA 9300 (South Africa); Ali, Yasir [Department of Physics, Sant Longowal Institute of Engineering and Technology, Longowal, District Sangrur 148106, Punjab (India); Sharma, Kashma [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein ZA 9300 (South Africa); Department of Chemistry, Shoolini University of Biotechnology and Management Sciences, Solan 173212 (India); Kumar, Vinod [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein ZA 9300 (South Africa); Sonkawade, R.G. [Inter University Accelerator Center, Aruna Asif Ali Marg, New Delhi 110067 (India); Dhaliwal, A.S. [Department of Physics, Sant Longowal Institute of Engineering and Technology, Longowal, District Sangrur 148106, Punjab (India); Swart, H.C., E-mail: swarthc@ufs.ac.za [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein ZA 9300 (South Africa)

    2014-03-15

    Highlights: • Two steps electrochemical synthesis for the fabrication of Ag-polypyrrole composite films. • Surface modifications by swift heavy ion beam. • SEM image shows the formation of craters and humps after irradiation. • Detailed structural analysis by Raman spectroscopy. - Abstract: The general aim of this work was to study the effects of swift heavy ions on the properties of electrochemically synthesized Ag-polypyrrole composite thin films. Initially, polypyrrole (PPy) films were electrochemically synthesized on indium tin oxide coated glass surfaces using a chronopotentiometery technique, at optimized process conditions. The prepared PPy films have functioned as working electrodes for the decoration of submicron Ag particles on the surface of the PPy films through a cyclicvoltammetry technique. Towards probing the effect of swift heavy ion irradiation on the structural and morphological properties, the composite films were subjected to a 40 MeV Li{sup 3+} ion beam irradiation for various fluences (1 × 10{sup 11}, 1 × 10{sup 12} and 1 × 10{sup 13} ions/cm{sup 2}). Comparative microstructural investigations were carried out after the different ion fluences using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy and micro-Raman spectroscopy techniques. Raman and SEM studies revealed that the structure of the films became disordered after irradiation. The SEM studies of irradiated composite films show significant changes in their surface morphologies. The surface was smoother at lower fluence but craters were observed at higher fluence.

  1. Biocorrosion studies of TiO2 nanoparticle-coated Ti-6Al-4V implant in simulated biofluids

    International Nuclear Information System (INIS)

    Zaveri, Nikita; McEwen, Gerald D.; Karpagavalli, Ramji; Zhou Anhong

    2010-01-01

    The corrosion behaviors of the TiO 2 nanoparticles coated bioimplant Ti-6Al-4V exposed to three different simulated biofluids (SBF), namely, (1) NaCl solution, (2) Hank's solution, and (3) Cigada solution, were studied by using micro-Raman spectroscopy, electrochemical techniques, and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS). The different electrochemical impedance spectroscopy models were applied to fit the data obtained from the implants before and after the coating of TiO 2 nanoparticles (50-100 nm). It was found that the TiO 2 nanoparticle coatings increased the thickness of the pre-existing oxide layer on the Ti-6Al-4V surface, serving to improve the bioimplant corrosion resistance.

  2. Biocorrosion studies of TiO2 nanoparticle-coated Ti-6Al-4V implant in simulated biofluids

    Science.gov (United States)

    Zaveri, Nikita; McEwen, Gerald D.; Karpagavalli, Ramji; Zhou, Anhong

    2010-06-01

    The corrosion behaviors of the TiO2 nanoparticles coated bioimplant Ti-6Al-4V exposed to three different simulated biofluids (SBF), namely, (1) NaCl solution, (2) Hank's solution, and (3) Cigada solution, were studied by using micro-Raman spectroscopy, electrochemical techniques, and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS). The different electrochemical impedance spectroscopy models were applied to fit the data obtained from the implants before and after the coating of TiO2 nanoparticles (50-100 nm). It was found that the TiO2 nanoparticle coatings increased the thickness of the pre-existing oxide layer on the Ti-6Al-4V surface, serving to improve the bioimplant corrosion resistance.

  3. Enhanced bonding between TiO2-Graphene oxide

    DEFF Research Database (Denmark)

    Naknikham, Usuma; Buffa, Vittorio; Yue, Yuanzheng

    analysis. Besides, the study of Ti-O-C and Ti-C interface bonding was carried out using XPS. The band-gap energy was determined using a UV-VIS spectrophotometer equipped with an integrating sphere. Thus, it was possible for us to determine the reactivity of the new photocatalysts under the visible light...... as photocatalysts, which can efficiently react with organic species under solar light and can enhance the adsorption of water pollutants [3]. Many studies have shown that TiO2-GO heterostructures can quickly mineralize organic dyes in solution under UV-light. However, it is not clear if these materials can provide...... the same performances under sunlight and with complex real water systems. Hence, this research aims to study the photocatalystic property on GO-TiO2 composites with aqueous solutions of selected emerging pollutants under visible light. The samples were synthesized via the in-situ sol-gel nucleation...

  4. Electrochemical Studies of Graphene-like materials Synthesized by the Thermolyzed Asphalt Reaction

    Science.gov (United States)

    Xie, Yuqun

    Developing a facile and cost effective synthetic method for producing graphene materials has been an attractive research topic in several disciplines. Chapter 3 demenstrates sheets of multilayered graphene-like paper materials more than 10 cm2 in area were synthesized in the "Thermolyzed Asphalt Reaction (TAR)". TAR is processed within open containers at 650 °C under atmospheric pressure without the need to exclude oxygen, which is the lowest reported temperature for chemical vapor deposition of graphene-based materials. It was found that multilayered graphene-like materials can be grown on amorphous substrates without catalysts. In chapter 4, further studies of the TAR mechanism have allowed sulfur to be identified as an important co-factor in multilayer graphene-like materials formation. Graphene-like material was produced from simple precursors such as elemental sulfur and cyclohexanol. A proposed scheme illustrates sulfur's role in the growth of graphene-like material based on thermogravimetric analyses. We hypothesize that elemental sulfur is involved with the dehydration/dehydrogenation and eventual crosslinking of cyclohexanol between 100-140 °C. In the range of 240-400 °C further dehydrogenation steps occur yielding an unidentified intermediate with a sharp Raman peak at 1450 cm-1 At 550 °C graphene-like Raman D and G bands appear along with the 1450 cm band of the intermediate. At 600 °C and higher temperatures, the intermediate peak is lost with only bands characteristic of graphene-like material being seen in the spectrum of the material synthesized from the University of Idaho Thermolyzed Asphalt Reaction (GUITAR). Sulfur as a key co-factor for GUITAR synthesis is reinforced by results found with other hydrocarbons. Other organics succeeded or failed in GUITAR formation based on melting and boiling considerations. The failure of the compounds with a boiling point below -89°C, melting point above 300°C is reasoned with the volatility of the

  5. Novel Ag@TiO2 nanocomposite synthesized by electrochemically active biofilm for nonenzymatic hydrogen peroxide sensor.

    Science.gov (United States)

    Khan, Mohammad Mansoob; Ansari, Sajid Ali; Lee, Jintae; Cho, Moo Hwan

    2013-12-01

    A novel nonenzymatic sensor for H2O2 was developed based on an Ag@TiO2 nanocomposite synthesized using a simple and cost effective approach with an electrochemically active biofilm. The optical, structural, morphological and electrochemical properties of the as-prepared Ag@TiO2 nanocomposite were examined by UV-vis spectroscopy, X-ray diffraction, transmission electron microscopy and cyclic voltammetry (CV). The Ag@TiO2 nanocomposite was fabricated on a glassy carbon electrode (GCE) and their electrochemical performance was analyzed by CV, differential pulse voltammetry and electrochemical impedance spectroscopy. The Ag@TiO2 nanocomposite modified GCE (Ag@TiO2/GCE) displayed excellent performance towards H2O2 sensing at -0.73 V in the linear response range from 0.83 μM to 43.3 μM, within a detection limit and sensitivity of 0.83 μM and ~65.2328±0.01 μA μM(-1) cm(-2), respectively. In addition, Ag@TiO2/GCE exhibited good operational reproducibility and long term stability. © 2013.

  6. Microstructure and corrosion performance of steam-based conversion coatings produced in the presence of TiO2 particles on aluminium alloys

    DEFF Research Database (Denmark)

    Din, Rameez Ud; Gudla, Visweswara Chakravarthy; Jellesen, Morten Stendahl

    2016-01-01

    The steam-based conversion coatings containing TiO2 particleswere prepared using a two-step process comprising of spin coating of particles onto an aluminiumsubstrate followed by a high-pressure steam treatment. Process has resulted in the formation of aluminium oxide layer (~1.3 μm thick) embedded...... to the coatings without TiO2 particles, while the shift in thepitting potential was a function of the steam treatment time and degree of particle incorporation into the oxide....... with TiO2 particles. The electrochemical measurements showthe beneficial effect of TiO2 particles in the oxide layer by exhibiting lowestanodic and cathodic activities, and reduced pit depth. The presence of TiO2 particles shifts the corrosion potentialvalues to positive side (noble side) when compared...

  7. TiO2-SnS2 nanocomposites: solar-active photocatalytic materials for water treatment.

    Science.gov (United States)

    Kovacic, Marin; Kusic, Hrvoje; Fanetti, Mattia; Stangar, Urska Lavrencic; Valant, Matjaz; Dionysiou, Dionysios D; Bozic, Ana Loncaric

    2017-08-01

    The study is aimed at evaluating TiO 2 -SnS 2 composites as effective solar-active photocatalysts for water treatment. Two strategies for the preparation of TiO 2 -SnS 2 composites were examined: (i) in-situ chemical synthesis followed by immobilization on glass plates and (ii) binding of two components (TiO 2 and SnS 2 ) within the immobilization step. The as-prepared TiO 2 -SnS 2 composites and their sole components (TiO 2 or SnS 2 ) were inspected for composition, crystallinity, and morphology using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX) analyses. Diffuse reflectance spectroscopy (DRS) was used to determine band gaps of immobilized TiO 2 -SnS 2 and to establish the changes in comparison to respective sole components. The activity of immobilized TiO 2 -SnS 2 composites was tested for the removal of diclofenac (DCF) in aqueous solution under simulated solar irradiation and compared with that of single component photocatalysts. In situ chemical synthesis yielded materials of high crystallinity, while their morphology and composition strongly depended on synthesis conditions applied. TiO 2 -SnS 2 composites exhibited higher activity toward DCF removal and conversion in comparison to their sole components at acidic pH, while only in situ synthesized TiO 2 -SnS 2 composites showed higher activity at neutral pH.

  8. Effect of zinc doping on the bandgap and photoluminescence of Zn2+-doped TiO2 nanowires

    Science.gov (United States)

    Loan, Trinh Thi; Huong, Vu Hoang; Tham, Vu Thi; Long, Nguyen Ngoc

    2018-03-01

    This study was focused on the effect of Zn2+ dopant concentration on the absorption edge and photoluminescence of anatase TiO2 nanowires synthesized by hydrothermal technique. For the undoped anatase TiO2 nanowires, the indirect band gap of 3.26 eV and the direct band gap of 3.58 eV are assigned to the indirect Γ3 → X1b and direct X2b → X1b transitions, respectively. The Zn2+-doping makes the absorption edge of TiO2:Zn2+ nanowires shift towards the lower energy side (red shift). On the other hand, the replacing Ti4+ ions with Zn2+ ions creates oxygen vacancies (VO) and shallow defects associated with VO. Just these defects are responsible for the enhanced luminescence of Zn2+-doped TiO2 nanowires.

  9. TiO2 nanorods/PMMA copolymer-based nanocomposites: highly homogeneous linear and nonlinear optical material

    International Nuclear Information System (INIS)

    Sciancalepore, C; Agostiano, A; Cassano, T; Valentini, A; Curri, M L; Striccoli, M; Mecerreyes, D; Tommasi, R

    2008-01-01

    Original nanocomposites have been obtained by direct incorporation of pre-synthesized oleic acid capped TiO 2 nanorods into properly functionalized poly(methyl methacrylate) copolymers, carrying carboxylic acid groups on the repeating polymer unit. The presence of carboxylic groups on the alkyl chain of the host functionalized copolymer allows an highly homogeneous dispersion of the nanorods in the organic matrix. The prepared TiO 2 /PMMA-co-MA nanocomposites show high optical transparency in the visible region, even at high TiO 2 nanorod content, and tunable linear refractive index depending on the nanoparticle concentration. Finally measurements of nonlinear optical properties of TiO 2 polymer nanocomposites demonstrate a negligible two-photon absorption and a negative value of nonlinear refractive index, highlighting the potential of the nanocomposite for efficient optical devices operating in the visible region

  10. TiO2 nanorods/PMMA copolymer-based nanocomposites: highly homogeneous linear and nonlinear optical material

    Science.gov (United States)

    Sciancalepore, C.; Cassano, T.; Curri, M. L.; Mecerreyes, D.; Valentini, A.; Agostiano, A.; Tommasi, R.; Striccoli, M.

    2008-05-01

    Original nanocomposites have been obtained by direct incorporation of pre-synthesized oleic acid capped TiO2 nanorods into properly functionalized poly(methyl methacrylate) copolymers, carrying carboxylic acid groups on the repeating polymer unit. The presence of carboxylic groups on the alkyl chain of the host functionalized copolymer allows an highly homogeneous dispersion of the nanorods in the organic matrix. The prepared TiO2/PMMA-co-MA nanocomposites show high optical transparency in the visible region, even at high TiO2 nanorod content, and tunable linear refractive index depending on the nanoparticle concentration. Finally measurements of nonlinear optical properties of TiO2 polymer nanocomposites demonstrate a negligible two-photon absorption and a negative value of nonlinear refractive index, highlighting the potential of the nanocomposite for efficient optical devices operating in the visible region.

  11. VO2/TiO2 Nanosponges as Binder-Free Electrodes for High-Performance Supercapacitors

    Science.gov (United States)

    Hu, Chenchen; Xu, Henghui; Liu, Xiaoxiao; Zou, Feng; Qie, Long; Huang, Yunhui; Hu, Xianluo

    2015-11-01

    VO2/TiO2 nanosponges with easily tailored nanoarchitectures and composition were synthesized by electrostatic spray deposition as binder-free electrodes for supercapacitors. Benefiting from the unique interconnected pore network of the VO2/TiO2 electrodes and the synergistic effect of high-capacity VO2 and stable TiO2, the as-formed binder-free VO2/TiO2 electrode exhibits a high capacity of 86.2 mF cm-2 (~548 F g-1) and satisfactory cyclability with 84.3% retention after 1000 cycles. This work offers an effective and facile strategy for fabricating additive-free composites as high-performance electrodes for supercapacitors.

  12. Sonochemical synthesis and photocatalytic activity of meso- and macro-porous TiO2 for oxidation of toluene

    International Nuclear Information System (INIS)

    Yang Liu; Yan Li; Wang Yuntao; Xie Lei; Zheng Jie; Li Xingguo

    2008-01-01

    Meso-and macro-porous TiO 2 were synthesized by ultrasonic induced solvothermal method. Octadecylamine as a soft template was used to direct the formation of porous structure. The as-prepared porous TiO 2 was characterized by low angle and wide angle X-ray diffraction, N 2 adsorption-desorption isotherms and BET surface area. The energy influence of ultrasound and heat and concentration of nitric acid for post extraction on formation of porous structure were investigated. The photocatalytic activities of TiO 2 were investigated by degrading toluene gas under UV light. The results revealed that proper energy facilitates the formation of porous structure and too low concentration of nitric acid cannot extract template from pores. The photocatalytic activities of TiO 2 with porous structure are higher than those of nonporous ones

  13. One-step synthesis of hierarchically porous hybrid TiO2 hollow spheres with high photocatalytic activity

    Science.gov (United States)

    Liu, Ruiping; Ren, Feng; Yang, Jinlin; Su, Weiming; Sun, Zhiming; Zhang, Lei; Wang, Chang-an

    2016-03-01

    Hierarchically porous hybrid TiO2 hollow spheres were solvothermally synthesized successfully by using tetrabutyl titanate as titanium precursor and hydrated metal sulfates as soft templates. The as-prepared TiO2 spheres with hierarchically pore structures and high specific surface area and pore volume consisted of highly crystallized anatase TiO2 nanocrystals hybridized with a small amount of metal oxide from the hydrated sulfate. The proposed hydrated-sulfate assisted solvothermal (HAS) synthesis strategy was demonstrated to be widely applicable to various systems. Evaluation of the hybrid TiO2 hollow spheres for the photo-decomposition of methyl orange (MO) under visible-light irradiation revealed that they exhibited excellent photocatalytic activity and durability.

  14. Structural, Optical, Morphological and Elemental Analysis on Sol-gel Synthesis of Ni Doped TiO2 Nanocrystallites

    Directory of Open Access Journals (Sweden)

    T. Sakthivel

    2017-06-01

    Full Text Available Pure and Ni doped titanium dioxide nanoparticles were successfully synthesized by sol-gel method and characterized usingXRD, UV-Visible, FTIR, FESEM and EDS techniques. XRD pattern confirms the formation of tetragonal TiO2. The absorbance spectra of pure and Ni doped TiO2 showed absorption spectrum at ultra-violet region due to electronic transition between bonding and anti-bonding orbital (π-π•. Bandgap energy of Ni doped TiO2 decreased to 2.5 eV when compared to pure TiO2 (3.39 eV. FESEM study reveals agglomerated spherical shaped morphology. The functional groups of the prepared samples were identified using FTIR spectroscopy and the elemental analysis was further supported with EDS analysis.

  15. VO2/TiO2 Nanosponges as Binder-Free Electrodes for High-Performance Supercapacitors.

    Science.gov (United States)

    Hu, Chenchen; Xu, Henghui; Liu, Xiaoxiao; Zou, Feng; Qie, Long; Huang, Yunhui; Hu, Xianluo

    2015-11-04

    VO2/TiO2 nanosponges with easily tailored nanoarchitectures and composition were synthesized by electrostatic spray deposition as binder-free electrodes for supercapacitors. Benefiting from the unique interconnected pore network of the VO2/TiO2 electrodes and the synergistic effect of high-capacity VO2 and stable TiO2, the as-formed binder-free VO2/TiO2 electrode exhibits a high capacity of 86.2 mF cm(-2) (~548 F g(-1)) and satisfactory cyclability with 84.3% retention after 1000 cycles. This work offers an effective and facile strategy for fabricating additive-free composites as high-performance electrodes for supercapacitors.

  16. Mixed matrix membranes prepared from high impact polystyrene with dispersed TiO2 nanoparticles for gas separation

    Directory of Open Access Journals (Sweden)

    P. Safaei

    2016-01-01

    Full Text Available The current study presents synthesis and characterization of high impact polystyrene - TiO2 nanoparticles mixed matrix membranes for separation of carbon dioxide from nitrogen. The solution-casting method was used for preparation of membranes. The nano mixed matrix membranes were characterized using scanning electron microscopy to ensure the suitable dispersion of nano particles in high impact polystyrene matrix. The effect of TiO2 nanoparticles loading on membrane performance was investigated. The separation performance of synthesized membranes was investigated in separation of CO2 from CO2/N2 mixture. Effect of feed pressure and TiO2 content on separation of CO2 was studied. The results revealed that increase of feed pressure decreases flux of gases through the mixed matrix membrane. The results also confirmed that the best separation performance can be obtained at TiO2 nanoparticles loading of 7 wt.%.

  17. Three-dimensional assembly structure of anatase TiO2 hollow microspheres with enhanced photocatalytic performance

    Science.gov (United States)

    Tang, Yihao; Zhan, Shuai; Wang, Li; Zhang, Bin; Ding, Minghui

    The pure anatase TiO2 hollow microspheres are synthesized by a one-step template-free hydrothermal route. By defining temperature and time limits, we produce TiO2 hollow microspheres with a fluoride-mediated self-transformation. The surface morphology of TiO2 hollow microspheres was studied by SEM. The hollow microspheres have diameters of about 800 nm and are remarkably uniform. The UV-light photocatalytic activity and the stability/multifunction of TiO2 hollow microspheres structure were evaluated by photocatalytic degradation of methylene blue and photocatalytic hydrogen evolution. The excellent photocatalytic activity is attributed to large specific surface area, more active sites, unique hollow structures, and improved light scattering.

  18. Adsorption and photocatalysis for methyl orange and Cd removal from wastewater using TiO2/sewage sludge-based activated carbon nanocomposites

    Science.gov (United States)

    Rashed, M. Nageeb; Eltaher, M. A.; Abdou, A. N. A.

    2017-12-01

    Nanocomposite TiO2/ASS (TiO2 nanoparticle coated sewage sludge-based activated carbon) was synthesized by the sol-gel method. The changes in surface properties of the TiO2/ASS nanocomposite were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and X-ray fluorescence. The prepared TiO2/ASS nanocomposite was applied for simultaneous removal of methyl orange dye (MO) and Cd2+ from bi-pollutant solution. The factors influencing photocatalysis (TiO2 : ASS ratios, initial pollutant concentrations, solution pH, nanocomposite dosage and UV irradiation time) were investigated. The results revealed that high removal efficiency of methyl orange dye (MO) and Cd2+ from bi-pollutant solution was achieved with TiO2/ASS at a ratio (1 : 2). The obtained results revealed that degradation of MO dye on the TiO2/ASS nanocomposite was facilitated by surface adsorption and photocatalytic processes. The coupled photocatalysis and adsorption shown by TiO2/ASS nanocomposite resulted in faster and higher degradation of MO as compared to MO removal by ASS adsorbent. The removal efficiency of MO by ASS adsorbent and TiO2/ASS (1 : 2) nanocomposite at optimum pH value 7 were 74.14 and 94.28%, respectively, while for Cd2+ it was more than 90%. The experimental results fitted well with the second-order kinetic reaction.

  19. Preparation of Oleyl Phosphate-Modified TiO2/Poly(methyl methacrylate Hybrid Thin Films for Investigation of Their Optical Properties

    Directory of Open Access Journals (Sweden)

    Masato Fujita

    2015-01-01

    Full Text Available TiO2 nanoparticles (NPs modified with oleyl phosphate were synthesized through stable Ti–O–P bonds and were utilized to prepare poly(methyl methacrylate- (PMMA- based hybrid thin films via the ex situ route for investigation of their optical properties. After surface modification of TiO2 NPs with oleyl phosphate, IR and 13C CP/MAS NMR spectroscopy showed the presence of oleyl groups. The solid-state 31P MAS NMR spectrum of the product revealed that the signal due to oleyl phosphate (OP shifted upon reaction, indicating formation of covalent Ti–O–P bonds. The modified TiO2 NPs could be homogeneously dispersed in toluene, and the median size was 16.1 nm, which is likely to be sufficient to suppress Rayleigh scattering effectively. The TEM images of TiO2/PMMA hybrid thin films also showed a homogeneous dispersion of TiO2 NPs, and they exhibited excellent optical transparency even though the TiO2 content was 20 vol%. The refractive indices of the OP-modified TiO2/PMMA hybrid thin films changed higher with increases in TiO2 volume fraction, and the hybrid thin film with 20 vol% of TiO2 showed the highest refractive index (n = 1.86.

  20. Rapid fabrication of mesoporous TiO2 thin films by pulsed fibre laser for dye sensitized solar cells

    Science.gov (United States)

    Hadi, Aseel; Alhabradi, Mansour; Chen, Qian; Liu, Hong; Guo, Wei; Curioni, Michele; Cernik, Robert; Liu, Zhu

    2018-01-01

    In this paper we demonstrate for the first time that a fibre laser with a wavelength of 1070 nm and a pulse width of milliseconds can be applied to generate mesoporous nanocrystalline (nc) TiO2 thin films on ITO coated glass in ambient atmosphere, by complete vaporisation of organic binder and inter-connection of TiO2 nanoparticles, without thermally damaging the ITO layer and the glass substrate. The fabrication of the mesoporous TiO2 thin films was achieved by stationary laser beam irradiation of 1 min. The dye sensitized solar cell (DSSC) with the laser-sintered TiO2 photoanode reached higher power conversion efficiency (PCE) of 3.20% for the TiO2 film thickness of 6 μm compared with 2.99% for the furnace-sintered. Electrochemical impedance spectroscopy studies revealed that the laser sintering under the optimised condition effectively decreased charge transfer resistance and increased electron lifetime of the TiO2 thin films. The use of the fibre laser with over 40% wall-plug efficiency offers an economically-feasible, industrial viable solution to the major challenge of rapid fabrication of large scale, mass production of mesoporous metal oxide thin film based solar energy systems, potentially for perovskite and monolithic tandem solar cells, in the future.

  1. Water Adsorption on TiO2

    DEFF Research Database (Denmark)

    Hammer, Bjørk; Wendt, Stefan; Besenbacher, Flemming

    2010-01-01

    Scanning Tunneling Microscopy (STM) studies and Density Functional Theory (DFT) investigations of the interaction of water with the rutile TiO2 (110) surface are summarized. From high-resolution STM the following reactions have been revealed: water adsorption and diffusion in the Ti troughs, water...... dissociation in bridging oxygen vacancies, assembly of adsorbed water monomers into rapidly diffusing water dimers, and formation of water dimers by reduction of oxygen molecules. The STM results are rationalized based on DFT calculations, revealing the bonding geometries and reaction pathways of the water...

  2. Solid-state synthesis of Li_4Ti_5O_1_2 whiskers from TiO_2-B

    International Nuclear Information System (INIS)

    Yao, Wenjun; Zhuang, Wei; Ji, Xiaoyan; Chen, Jingjing; Lu, Xiaohua; Wang, Changsong

    2016-01-01

    Highlights: • The Li_4Ti_5O_1_2 whiskers were synthesized from TiO_2-B whiskers via a solid state reaction. • The TiO_2-B crystal structure for lithium diffusion is easier than anatase. • The separated diffusion and reaction process is crucial for the solid-state syntheses of Li_4Ti_5O_1_2 whiskers. - Abstract: In this work, Li_4Ti_5O_1_2 (LTO) was synthesized from the precursors of TiO_2-B and anatase whiskers, respectively. The synthesized LTO whiskers from TiO_2-B whiskers via a solid state reaction at 650 °C have a high degree of crystallinity with an average diameter of 300 nm. However, when anatase whiskers were used as the precursor, only particle morphology LTO was produced at 750 °C. The further analysis of the precursors, the intermediate products and the final products reveal that the crystal structure of the anatase hinders the diffusion of lithium, leading to a typical reaction–diffusion process. Under this condition, only particle morphology LTO can be produced. However, the crystal structure of the TiO_2-B is easy for lithium diffusion and the process is performed in two separated steps (i.e., diffusion and reaction), which makes it possible to decrease the solid-state reaction temperature down to 650 °C and then maintain the morphologies of whiskers.

  3. Synthesis of TiO2 nanorod-decorated graphene sheets and their highly efficient photocatalytic activities under visible-light irradiation

    International Nuclear Information System (INIS)

    Lee, Eunwoo; Hong, Jin-Yong; Kang, Haeyoung; Jang, Jyongsik

    2012-01-01

    Highlights: ► TiO 2 nanorods were successfully decorated on the surface of graphene sheets. ► Population of TiO 2 nanorods can be controlled by changing experimental conditions. ► TiO 2 nanorod-decorated graphene sheets have an expanded light absorption range. ► TiO 2 nanorod-decorated graphene sheets showed unprecedented photocatalytic activity. - Abstract: The titanium dioxide (TiO 2 ) nanorod-decorated graphene sheets photocatalysts with different TiO 2 nanorods population have been synthesized by a simple non-hydrolytic sol–gel approach. Electron microscopy and X-ray diffraction analysis indicated that the TiO 2 nanorods are well-dispersed and successfully anchored on the graphene sheet surface through the formation of covalent bonds between Ti and C atoms. The photocatalytic activities are evaluated in terms of the efficiencies of photodecomposition and adsorption of methylene blue (MB) in aqueous solution under visible-light irradiation. The as-synthesized TiO 2 nanorod-decorated graphene sheets showed unprecedented photodecomposition efficiency compared to the pristine TiO 2 nanorods and the commercial TiO 2 (P-25, Degussa) under visible-light. It is believed that this predominant photocatalytic activity is due to the synergistic contribution of both a retarded charge recombination rate caused by a high electronic mobility of graphene and an increased surface area originated from nanometer-sized TiO 2 nanorods. Furthermore, photoelectrochemical study is performed to give deep insights into the primary roles of graphene that determines the photocatalytic activity.

  4. TiO2 Deposition on AZ31 Magnesium Alloy Using Plasma Electrolytic Oxidation

    Directory of Open Access Journals (Sweden)

    Leon White

    2013-01-01

    Full Text Available Plasma electrolytic oxidation (PEO has been used in the past as a useful surface treatment technique to improve the anticorrosion properties of Mg alloys by forming protective layer. Coatings were prepared on AZ31 magnesium alloy in phosphate electrolyte with the addition of TiO2 nanoparticles using plasma electrolytic oxidation (PEO. This present work focuses on developing a TiO2 functional coating to create a novel electrophotocatalyst while observing the surface morphology, structure, composition, and corrosion resistance of the PEO coating. Microstructural characterization of the coating was investigated by X-ray diffraction (XRD and scanning electron microscopy (SEM followed by image analysis and energy dispersive spectroscopy (EDX. The corrosion resistance of the PEO treated samples was evaluated with electrochemical impedance spectroscopy (EIS and DC polarization tests in 3.5 wt.% NaCl. The XRD pattern shows that the components of the oxide film include Mg from the substrate as well as MgO and Mg2TiO4 due to the TiO2 nanoparticle addition. The results show that the PEO coating with TiO2 nanoparticles did improve the corrosion resistance when compared to the AZ31 substrate alloy.

  5. Porous TiO2 Conformal Coating on Carbon Nanotubes as Energy Storage Materials

    International Nuclear Information System (INIS)

    Yan, Litao; Xu, Yun; Zhou, Meng; Chen, Gen; Deng, Shuguang; Smirnov, Sergei; Luo, Hongmei; Zou, Guifu

    2015-01-01

    The controllable synthesis of strongly coupled inorganic materials/carbon nanotubes (CNTs) hybrids represents a long-standing challenge for developing advanced catalysts and energy-storage materials. Here we report a simple sol-gel method for facile synthesis of TiO 2 /CNTs hybrid. The porous anatase TiO 2 nanoparticles are uniformly coated on the CNTs conducting network, which leads to remarkably improved electrochemical performances such as exceptional cycling stability, good high rate durability, and reduced resistance. This hybrid exhibits a reversible capacity as high as 200 mA·h g −1 at a current density of 0.1 A g −1 as an anode in lithium-ion battery (LIB). As a supercapacitor (SC), it shows a specific supercapacitance of 145 F g −1 in 0.5 M H 2 SO 4 electrolyte, higher than that of the previously reported TiO 2 based supercapacitors. Moreover, this hybrid also exhibits excellent durability after 1000 cycles for both LIBs and SCs. Such superior performance and cycling durability demonstrate the reinforced synergistic effects between the porous TiO 2 and interweaved CNTs network, indicating a great application potential for such hybrid materials in high power LIBs and SCs

  6. The effect of TiO2 nanocrystal shape on the electrical properties of poly(styrene-b-methyl methacrylate) block copolymer based nanocomposites for solar cell application

    International Nuclear Information System (INIS)

    Cano, Laida; Gutierrez, Junkal; Di Mauro, A. Evelyn; Curri, M. Lucia; Tercjak, Agnieszka

    2015-01-01

    Titanium dioxide (TiO 2 ) nanocrystals were synthesized into two shapes, namely spherical and rod-like and used for the fabrication of polystyrene-block-poly(methyl methacrylate) (PSMMA) block copolymer based nanocomposites, which were employed as the active top layer of electro-devices for solar cell application. Electro-devices were designed using nanocomposites with high TiO 2 nanocrystal contents (50-70 wt%) and for comparison as-synthesized TiO 2 nanospheres (TiO 2 NSs) and TiO 2 nanorods (TiO 2 NRs) were also used. The morphology of the electro-devices was studied by atomic force microscopy showing good nanocrystal dispersion. The electrical properties of the devices were investigated by PeakForce tunneling atomic force microscopy and Keithley semiconductor analyzer, which showed higher electrical current values for devices containing TiO 2 NRs in comparison to TiO 2 NSs. Remarkably, the influence of the PSMMA block copolymer on the improvement of the conductivity of the electro-devices was also assessed, demonstrating that the self-assembling ability of block copolymer can be beneficial to improve charge transfer in the fabricated electro-devices, thus representing relevant systems to be potentially developed for photovoltaic applications. Moreover, the absorbance of the prepared electro-devices in solar irradiation range was confirmed by UV–vis spectroscopy characterization.

  7. Bactericidal effect of blue LED light irradiated TiO2/Fe3O4 particles on fish pathogen in seawater

    International Nuclear Information System (INIS)

    Cheng, T.C.; Yao, K.S.; Yeh, N.; Chang, C.I.; Hsu, H.C.; Gonzalez, F.; Chang, C.Y.

    2011-01-01

    This study uses blue LED light (λ max = 475 nm) activated TiO 2 /Fe 3 O 4 particles to evaluate the particles' photocatalytic activity efficiency and bactericidal effects in seawater of variable salinities. Different TiO 2 to Fe 3 O 4 mole ratios have been synthesized using sol-gel method. The synthesized particles contain mainly anatase TiO 2 , Fe 3 O 4 and FeTiO 3 . The study has identified TiO 2 /Fe 3 O 4 's bactericidal effect to marine fish pathogen (Photobacterium damselae subsp. piscicida BCRC17065) in seawater. The SEM photo reveals the surface destruction in bacteria incubated with blue LED irradiated TiO 2 /Fe 3 O 4 . The result of this study indicates that 1) TiO 2 /Fe 3 O 4 acquires photocatalytic activities in both the freshwater and the seawater via blue LED irradiation, 2) higher photocatalytic activities appear in solutions of higher TiO 2 /Fe 3 O 4 mole ratio, and 3) photocatalytic activity decreases as salinity increases. These results suggest that the energy saving blue LED light is a feasible light source to activate TiO 2 /Fe 3 O 4 photocatalytic activities in both freshwater and seawater.

  8. Optimization of charge transfer and transport processes at the CdSe quantum dots/TiO2 nanorod interface by TiO2 interlayer passivation

    International Nuclear Information System (INIS)

    Jaramillo-Quintero, O A; Rincon, M E; Triana, M A

    2017-01-01

    Surface trap states hinder charge transfer and transport properties in TiO 2 nanorods (NRs), limiting its application on optoelectronic devices. Here, we study the interfacial processes between rutile TiO 2 NR and CdSe quantum dots (QDs) using TiO 2 interlayer passivation treatments. Anatase or rutile TiO 2 thin layers were deposited on an NR surface by two wet-chemical deposition treatments. Reduced interfacial charge recombination between NRs and CdSe QDs was observed by electrochemical impedance spectroscopy with the introduction of TiO 2 thin film interlayers compared to bare TiO 2 NRs. These results can be ascribed to in-gap trap state passivation of the TiO 2 NR surface, which led to an increase in open circuit voltage. Moreover, the rutile thin layer was more efficient than anatase to promote a higher photo-excited electron transfer from CdSe QDs to TiO 2 NRs due to a large driving force for charge injection, as confirmed by surface photovoltage spectroscopy. (paper)

  9. Controlled hydrodynamic conditions on the formation of iron oxide nanostructures synthesized by electrochemical anodization: Effect of the electrode rotation speed

    International Nuclear Information System (INIS)

    Lucas-Granados, Bianca; Sánchez-Tovar, Rita; Fernández-Domene, Ramón M.; García-Antón, Jose

    2017-01-01

    Highlights: • Novel iron anodization process under controlled dynamic conditions was evaluated. • Iron oxide nanostructures composed mainly by hematite were synthesized. • Different morphologies were obtained depending on the electrode rotation speed. • A suitable photocatalyst was obtained by stirring the electrode at 1000 rpm.. - Abstract: Iron oxide nanostructures are of particular interest because they can be used as photocatalysts in water splitting due to their advantageous properties. Electrochemical anodization is one of the best techniques to synthesize nanostructures directly on the metal substrate (direct back contact). In the present study, a novel methodology consisting of the anodization of iron under hydrodynamic conditions is carried out in order to obtain mainly hematite (α-Fe 2 O 3 ) nanostructures to be used as photocatalysts for photoelectrochemical water splitting applications. Different rotation speeds were studied with the aim of evaluating the obtained nanostructures and determining the most attractive operational conditions. The synthesized nanostructures were characterized by means of Raman spectroscopy, Field Emission Scanning Electron Microscopy, photoelectrochemical water splitting, stability against photocorrosion tests, Mott-Schottky analysis, Electrochemical Impedance Spectroscopy (EIS) and band gap measurements. The results showed that the highest photocurrent densities for photoelectrochemical water splitting were achieved for the nanostructure synthesized at 1000 rpm which corresponds to a nanotubular structure reaching ∼0.130 mA cm −2 at 0.54 V (vs. Ag/AgCl). This is in agreement with the EIS measurements and Mott-Schottky analysis which showed the lowest resistances and the corresponding donor density values, respectively, for the nanostructure anodized at 1000 rpm.

  10. Controlled hydrodynamic conditions on the formation of iron oxide nanostructures synthesized by electrochemical anodization: Effect of the electrode rotation speed

    Energy Technology Data Exchange (ETDEWEB)

    Lucas-Granados, Bianca; Sánchez-Tovar, Rita; Fernández-Domene, Ramón M.; García-Antón, Jose, E-mail: jgarciaa@iqn.upv.es

    2017-01-15

    Highlights: • Novel iron anodization process under controlled dynamic conditions was evaluated. • Iron oxide nanostructures composed mainly by hematite were synthesized. • Different morphologies were obtained depending on the electrode rotation speed. • A suitable photocatalyst was obtained by stirring the electrode at 1000 rpm.. - Abstract: Iron oxide nanostructures are of particular interest because they can be used as photocatalysts in water splitting due to their advantageous properties. Electrochemical anodization is one of the best techniques to synthesize nanostructures directly on the metal substrate (direct back contact). In the present study, a novel methodology consisting of the anodization of iron under hydrodynamic conditions is carried out in order to obtain mainly hematite (α-Fe{sub 2}O{sub 3}) nanostructures to be used as photocatalysts for photoelectrochemical water splitting applications. Different rotation speeds were studied with the aim of evaluating the obtained nanostructures and determining the most attractive operational conditions. The synthesized nanostructures were characterized by means of Raman spectroscopy, Field Emission Scanning Electron Microscopy, photoelectrochemical water splitting, stability against photocorrosion tests, Mott-Schottky analysis, Electrochemical Impedance Spectroscopy (EIS) and band gap measurements. The results showed that the highest photocurrent densities for photoelectrochemical water splitting were achieved for the nanostructure synthesized at 1000 rpm which corresponds to a nanotubular structure reaching ∼0.130 mA cm{sup −2} at 0.54 V (vs. Ag/AgCl). This is in agreement with the EIS measurements and Mott-Schottky analysis which showed the lowest resistances and the corresponding donor density values, respectively, for the nanostructure anodized at 1000 rpm.

  11. Low temperature synthesis of polyaniline-crystalline TiO2-halloysite composite nanotubes with enhanced visible light photocatalytic activity.

    Science.gov (United States)

    Li, Cuiping; Wang, Jie; Guo, Hong; Ding, Shujiang

    2015-11-15

    A series of one-dimensional polyaniline-crystalline TiO2-halloysite composite nanotubes with different mass ratio of polyaniline to TiO2 are facilely prepared by employing the low-temperature synthesis of crystalline TiO2 on halloysite nanotubes. The halloysite nanotubes can adsorb TiO2/polyaniline precursors and induce TiO2 nanocrystals/polyaniline to grow on the support in situ simultaneously. By simply adjusting the acidity of reaction system, PANI-crystalline TiO2-HA composite nanotubes composed of anatase, a mixed phase TiO2 and different PANI redox state are obtained. The XRD and UV-vis results show that the surface polyaniline sensitization has no effect on the crystalline structure of halloysite and TiO2 and the light response of TiO2 is extended to visible-light regions. Photocatalysis test results reveal the photocatalytic activity will be affected by the pH value and the volume ratio of ANI to TTIP. The highest photocatalytic activity is achieved with the composite photocatalysts prepared at pH 0.5 and 1% volume ratio of ANI and TTIP owing to the sensitizing effect of polyaniline and the charge transfer from the photoexcited PANI sensitizer to TiO2. Moreover, the PANI-TiO2-HA composite nanotubes synthesized by one-step at pH 0.5 with 1% volume ratio of ANI to TTIP exhibit higher visible light photocatalytic activity than those synthesized by the two-step. Heterogeneous PANI-TiO2-HA composite nanotubes prepared at pH 0.5 exhibit a higher degradation activity than that prepared at pH 1.5. The redoped experiment proves that the PANI redox state plays the main contribution to the enhanced visible light catalytic degradation efficiency of PANI-TiO2-HA prepared at pH 0.5. Furthermore, the heterogeneous PANI-crystalline TiO2-HA nanotubes have good photocatalytic stability and can be reused four times with only gradual loss of activity under visible light irradiation. Copyright © 2015 Elsevier Inc. All rights reserved.

  12. Synthesis and characterization of high photocatalytic activity and stable Ag3PO4/TiO2 fibers for photocatalytic degradation of black liquor

    International Nuclear Information System (INIS)

    Cai, Li; Long, Qiyi; Yin, Chao

    2014-01-01

    Highlights: • Ag 3 PO 4 /TiO 2 fibers were prepared via in situ Ag 3 PO 4 particles onto the surface of TiO 2 fiber. • Ag 3 PO 4 /TiO 2 fibers have stronger catalytic activity and excellent chemical stability. • Ag 3 PO 4 /TiO 2 fibers act as an efficient catalyst for the photocatalytic degradation of black liquor. - Abstract: The TiO 2 fiber was prepared by using cotton fiber as a template, and then Ag 3 PO 4 /TiO 2 fibers were synthesized via in situ Ag 3 PO 4 particles onto the surface of TiO 2 fiber. Their structure and physical properties were characterized by means of scanning electron microscopy (SEM), specific surface analyzer, X-ray diffraction (XRD), UV–vis absorption spectra and photoluminescence spectra (PL). SEM analysis indicated that the well-defined surface morphology of natural cotton fiber was mostly preserved in TiO 2 and Ag 3 PO 4 /TiO 2 fibers. Compared with TiO 2 fiber, the absorbance wavelengths of Ag 3 PO 4 /TiO 2 fibers were apparently red shifted and the PL intensities revealed a significant decrease. By using the photocatalytic degradation of black liquor as a model reaction, the visible light and ultraviolet light catalytic efficiencies of TiO 2 , Ag 3 PO 4 and Ag 3 PO 4 /TiO 2 fibers were evaluated. The reaction results showed that Ag 3 PO 4 /TiO 2 fibers had stronger photocatalytic activity and excellent chemical stability in repeated and long-term applications. Therefore, the prepared Ag 3 PO 4 /TiO 2 fibers could act as an efficient catalyst for the photocatalytic degradation of black liquor, which suggested their promising applications. It was proposed that the • OH radicals played the leading role in the photocatalytic degradation of the black liquor by Ag 3 PO 4 /TiO 2 fibers system

  13. Synthesis, characterization and photocatalytic activity of Fe2O3-TiO2 nanoparticles and nanocomposites

    Directory of Open Access Journals (Sweden)

    M. Ahmadi Golsefidi

    2016-01-01

    Full Text Available In this pepper Fe2O3 nanoparticles were synthesized via a fast microwave method. Then Fe2O3-TiO2 nanocomposites were synthesized by a sonochemical-assisted method. The prepared products were characterized by X-ray diffraction pattern, scanning electron microscopy and Fourier transform infrared spectroscopy. The photocatalytic behaviour of Fe2O3-TiO2 nanocomposites was evaluated using the degradation of Rhodamine B under ultra violet irradiation. The results show that nanocomposites have applicable magnetic and photocatalytic performance.

  14. Hydrothermal synthesis of core–shell TiO_2 to enhance the photocatalytic hydrogen evolution

    International Nuclear Information System (INIS)

    Jiang, Jinghui; Zhou, Han; Zhang, Fan; Fan, Tongxiang; Zhang, Di

    2016-01-01

    Graphical abstract: Core–shell TiO_2 with interior cavity was synthesized by a hydrothermal approach to enhance the photocatalytic performance. - Highlights: • Core–shell TiO_2 with interior cavity can be synthesized by hydrothermal approach. • Multiple reflection of incident light in cavity can increase the absorption. • Rutile can optimize the bandgap and delay the charge recombination. - Abstract: A hydrothermal approach was designed to synthesize core–shell TiO_2 with interior cavity by making sodium dodecyl sulfonate (SDS) as the surfactant and the mixture of water and ethanol as the solvent. The control experiment of solvent reveals ethanol and water are responsible for the formation of sphere and interior cavity, respectively. Besides, SDS can assist the growth of core–shell structure, and the sizes of sphere and interior cavity can be tuned by regulating the reaction time or temperature. UV–vis absorption proves core–shell structure with interior cavity can increase the absorption of incident light to enhance the optical activity of final product. The calculated bandgap and photoluminescence (PL) analyses reveal the coexistence of rutile in final product can optimize the bandgap to 3.03 eV and delay the charge recombination. As a result, an effective photocatalytic hydrogen evolution under full spectrum irradiation can be harvested by the as-synthesized core–shell spheres to reach a quantum yield, approximately 9.57% at 340 nm wavelength.

  15. Experimental and Theoretical Structural Investigation of AuPt Nanoparticles Synthesized Using a Direct Electrochemical Method.

    Science.gov (United States)

    Lapp, Aliya S; Duan, Zhiyao; Marcella, Nicholas; Luo, Long; Genc, Arda; Ringnalda, Jan; Frenkel, Anatoly I; Henkelman, Graeme; Crooks, Richard M

    2018-05-11

    In this report, we examine the structure of bimetallic nanomaterials prepared by an electrochemical approach known as hydride-terminated (HT) electrodeposition. It has been shown previously that this method can lead to deposition of a single Pt monolayer on bulk-phase Au surfaces. Specifically, under appropriate electrochemical conditions and using a solution containing PtCl 4 2- , a monolayer of Pt atoms electrodeposits onto bulk-phase Au immediately followed by a monolayer of H atoms. The H atom capping layer prevents deposition of Pt multilayers. We applied this method to ∼1.6 nm Au nanoparticles (AuNPs) immobilized on an inert electrode surface. In contrast to the well-defined, segregated Au/Pt structure of the bulk-phase surface, we observe that HT electrodeposition leads to the formation of AuPt quasi-random alloy NPs rather than the core@shell structure anticipated from earlier reports relating to deposition onto bulk phases. The results provide a good example of how the phase behavior of macro materials does not always translate to the nano world. A key component of this study was the structure determination of the AuPt NPs, which required a combination of electrochemical methods, electron microscopy, X-ray absorption spectroscopy, and theory (DFT and MD).

  16. One-Step Nonaqueous Synthesis of Pure Phase TiO2 Nanocrystals from TiCl4 in Butanol and Their Photocatalytic Properties

    Directory of Open Access Journals (Sweden)

    Tieping Cao

    2011-01-01

    Full Text Available Pure phase TiO2 nanomaterials were synthesized by an autoclaving treatment of TiCl4 with butanol as a single alcohol source. It was found that the control of molar ratio of TiCl4 to butanol played an important role in determining the TiO2 crystal phase and morphology. A high molar ratio of TiCl4 to butanol favored the formation of anatase nanoparticles, whereas rutile nanorods were selectively obtained at a low molar ratio of TiCl4 to butanol. Evaluation of the photocatalytic activity of the synthesized TiO2 was performed in terms of decomposition of organic dye rhodamine B under ultraviolet irradiation. It turned out that the as-synthesized TiO2 crystallites possessed higher photocatalytic activities toward bleaching rhodamine B than Degussa P25, benefiting from theirhigh surface area, small crystal size as well as high crystallinity.

  17. Characterization and mechanism analysis of N doped TiO2 with visible light response and its enhanced visible activity

    International Nuclear Information System (INIS)

    Cheng Xiuwen; Yu Xiujuan; Xing Zipeng

    2012-01-01

    Nitrogen doped TiO 2 nanoparticles were synthesized through a hydrolysis-precipitation process using ammonia water as the doping species. The resulting materials were characterized by XRD, DRS, SPS, XPS and FT-IR. Further, the activity enhanced-mechanism was discussed in detail. XRD results showed that doping with nitrogen could effectively retard the phase transformation of TiO 2 from anatase to rutile and increase the anatase crystallinity. DRS and SPS results indicated that the light absorbance edge of nitrogen doped TiO 2 nanoparticle was obviously red-shifted to visible light region and the separation rates of photogenerated charge carriers were greatly improved, respectively. XPS and FT-IR analysis implied that the contents of surface hydroxyl groups were improved significantly and the VBM (valance bond maximum) of O2p was 2.3 eV. Under the visible light irradiation with 120 min, a 65.3% degradation rate of phenol could be achieved. The photocatalytic activity of nitrogen doped TiO 2 was 2.08 and 1.97 times than that of pure TiO 2 and P25 TiO 2 , respectively. The enhanced visible light activity was attributed to the well anatase crystallinity, small crystallite size, intense light absorbance edge in visible region, more content of surface hydroxyl groups and high separation efficiency of photogenerated charge carriers.

  18. Photocatalytic degradation of methylene blue on Fe3+-doped TiO2 nanoparticles under visible light irradiation

    Institute of Scientific and Technical Information of China (English)

    SU Bitao; WANG Ke; BAI Jie; MU Hongmei; TONG Yongchun; MIN Shixiong; SHE Shixiong; LEI Ziqiang

    2007-01-01

    Fe3+-doped TiO2 composite nanoparticles with different doping amounts were successfully synthesized using sol-gel method and characterized by X-ray diffraction (XRD),transmission electron microscopy (TEM) and ultraviolet-visible spectroscopy (UV-Vis) diffuse reflectance spectra (DRS). The photocatalytic degradation of methylene blue was used as a model reaction to evaluate the photocatalytic activity of Fe3+/TiO2 nanoparticles under visible light irradia-tion. The influence of doping amount of Fe3+ (ω: 0.00%-3.00%) on photocatalytic activities of TiO2 was investigated.Results show that the size of Fe3+/TiO2 particles decreases with the increase of the amount of Fe3+ and their absorptionspectra are broaden and absorption intensities are also increased. Doping Fe3+ can control the conversion of TiO2 from anatase to rutile. The doping amount of Fe3+ remarkably affects the activity of the catalyst, and the optimum efficiency occurs at about the doping amount of 0.3%. The appropriate doping of Fe3+ can markedly increase the catalytic activity of TiO2 under visible light irradiation.

  19. Microwave-induced solid-state synthesis of TiO2(B) nanobelts with enhanced lithium-storage properties

    International Nuclear Information System (INIS)

    Qiao Yun; Hu Xianluo; Huang Yunhui

    2012-01-01

    A fast and economical route based on an efficient microwave-induced solid-state process has been developed to synthesize metastable TiO 2 (B) nanobelts with widths of 30–100 nm and lengths up to a few micrometers on a large scale. This new method reduces the synthesis time for the preparation of TiO 2 (B) nanobelts to less than half an hour, allowing the screening of a wide range of reaction conditions for optimizing and scaling up the production and facilitating the formation of metastable phase TiO 2 (B). The as-formed TiO 2 (B) nanobelts exhibit enhanced lithium-storage performances, compared with the TiO 2 (B) product obtained by the conventional heating. This study provides a new way for large-scale industrial production of high-quality metastable TiO 2 (B) nanostructures. The products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy.

  20. Visible light photoelectrocatalysis with salicylic acid-modified TiO2 nanotube array electrode for p-nitrophenol degradation

    International Nuclear Information System (INIS)

    Wang Xin; Zhao Huimin; Quan Xie; Zhao Yazhi; Chen Shuo

    2009-01-01

    This research focused on immersion method synthesis of visible light active salicylic acid (SA)-modified TiO 2 nanotube array electrode and its photoelectrocatalytic (PEC) activity. The SA-modified TiO 2 nanotube array electrode was synthesized by immersing in SA solution with an anodized TiO 2 nanotube array electrode. Scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), UV-vis diffuse reflectance spectrum (DRS), and Surface photovoltage (SPV) were used to characterize this electrode. It was found that SA-modified TiO 2 nanotube array electrode absorbed well into visible region and exhibited enhanced visible light PEC activity on the degradation of p-nitrophenol (PNP). The degradation efficiencies increased from 63 to 100% under UV light, and 79-100% under visible light (λ > 400 nm), compared with TiO 2 nanotube array electrode. The enhanced PEC activity of SA-modified TiO 2 nanotube array electrode was attributed to the amount of surface hydroxyl groups introduced by SA-modification and the extension of absorption wavelength range.

  1. Ultrasonic Spray-Coating of Large-Scale TiO2 Compact Layer for Efficient Flexible Perovskite Solar Cells

    Directory of Open Access Journals (Sweden)

    Peng Zhou

    2017-02-01

    Full Text Available Flexible electronics have attracted great interest in applications for the wearable devices. Flexible solar cells can be integrated into the flexible electronics as the power source for the wearable devices. In this work, an ultrasonic spray-coating method was employed to deposit TiO2 nanoparticles on polymer substrates for the fabrication of flexible perovskite solar cells (PSCs. Pre-synthesized TiO2 nanoparticles were first dispersed in ethanol to prepare the precursor solutions with different concentrations (0.5 mg/mL, 1.0 mg/mL, 2.0 mg/mL and then sprayed onto the conductive substrates to produce compact TiO2 films with different thicknesses (from 30 nm to 150 nm. The effect of the different drying processes on the quality of the compact TiO2 film was studied. In order to further improve the film quality, titanium diisopropoxide bis(acetylacetonate (TAA was added into the TiO2-ethanol solution at a mole ratio of 1.0 mol % with respect to the TiO2 content. The final prepared PSC devices showed a power conversion efficiency (PCE of 14.32% based on the indium doped tin oxide coated glass (ITO-glass substrate and 10.87% on the indium doped tin oxide coated polyethylene naphthalate (ITO-PEN flexible substrate.

  2. Preparation of TiO2 thin films from autoclaved sol containing needle-like anatase crystals

    International Nuclear Information System (INIS)

    Ge Lei; Xu Mingxia; Fang Haibo; Sun Ming

    2006-01-01

    A new inorganic sol-gel method was introduced in this paper to prepare TiO 2 thin films. The autoclaved sol with needle-like anatase crystals was synthesized using titanyl sulfate (TiOSO 4 ) and peroxide (H 2 O 2 ) as starting materials. The transparent anatase TiO 2 thin films were prepared on glass slides from the autoclaved sol by sol-gel dip-coating method. A wide range of techniques such as Fourier transform infrared transmission spectra (FT-IR), X-ray diffraction (XRD), thermogravimetry-differential thermal analysis (TG-DTA), scanning electron microscopes, X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible spectrum were applied to characterize the autoclaved sol and TiO 2 thin films. The results indicate that the autoclaved sol is flavescent, semitransparent and stable at room temperature. The anatase crystals of TiO 2 films connect together to form net-like structure after calcined and the films become uniform with increasing heating temperature. The surface of the TiO 2 films contain not only Ti and O elements, but also a small amount of N and Na elements diffused from substrates during heat treatment. The TiO 2 films are transparent and their maximal light transmittances exceed 80% under visible light region

  3. Synthesis and characterization of TiO2 photocatalyst doped by transition metal ions (Fe3+, Cr3+ and V5+)

    International Nuclear Information System (INIS)

    Tuan Vu, Anh; Linh Bui, Thi Hai; Cuong Tran, Manh; Phuong Dang, Tuyet; Hoa Tran, Thi Kim; Tuan Nguyen, Quoc

    2010-01-01

    Nano TiO 2 was synthesized by the hydrothermal method. The sample was doped with transition metal ions (V, Cr and Fe) and non-metal (N). Doped TiO 2 samples were characterized by x-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and UV-Vis diffuse reflectance spectroscopy (UV-Vis). Photocatalytic activity in the mineralization of xylene (vapor phase), methylene blue and active dyer PR (liquid phase) was tested. In comparison with non-doped TiO 2 , V-, Cr-, Fe-doped TiO 2 and N-doped TiO 2 samples exhibited much higher photocatalytic activity using visible light instead of UV

  4. Fabrication of a TiO2-P25/(TiO2-P25+TiO2 nanotubes junction for dye sensitized solar cells

    Directory of Open Access Journals (Sweden)

    Nguyen Huy Hao

    2016-08-01

    Full Text Available The dye sensitized solar cell (DSSC, which converts solar light into electric energy, is expected to be a promising renewable energy source for today's world. In this work, dye sensitized solar cells, one containing a single layer and one containing a double layer, were fabricated. In the double layer DSSC structure, the under-layer was TiO2-P25 film, and the top layer consisted of a mixture of TiO2-P25 and TiO2 nanotubes. The results indicated that the efficiency of the DSSC with the double layer structure was a significant improvement in comparison to the DSSC consisting of only a single film layer. The addition of TiO2-P25 in the top layer caused an improvement in the adsorption of dye molecules on the film rather than on the TiO2 nanotubes only. The presence of the TiO2 nanotubes together with TiO2-P25 in the top layer revealed the enhancement in harvesting the incident light and an improvement of electron transport through the film.

  5. Low Loss Sol-Gel TiO2 Thin Films for Waveguiding Applications

    Directory of Open Access Journals (Sweden)

    Alexis Fischer

    2013-03-01

    Full Text Available TiO2 thin films were synthesized by sol-gel process: titanium tetraisopropoxide (TTIP was dissolved in isopropanol, and then hydrolyzed by adding a water/isopropanol mixture with a controlled hydrolysis ratio. The as prepared sol was deposited by “dip-coating” on a glass substrate with a controlled withdrawal speed. The obtained films were annealed at 350 and 500 °C (2 h. The morphological properties of the prepared films were analyzed by Scanning Electron Microscopy (SEM and Atomic Force Microscopy (AFM. The optical waveguiding properties of TiO2 films were investigated for both annealing temperature using m-lines spectroscopy. The refractive indices and the film thickness were determined from the measured effective indices. The results show that the synthesized planar waveguides are multimodes and demonstrate low propagation losses of 0.5 and 0.8 dB/cm for annealing temperature 350 and 500 °C, respectively.

  6. Structural phase analysis and photoluminescence properties of Mg-doped TiO2 nanoparticles

    Science.gov (United States)

    Ali, T.; Ashraf, M. Anas; Ali, S. Asad; Ahmed, Ateeq; Tripathi, P.

    2018-05-01

    In this paper, we report the synthesis, characterization and photoluminescence properties of Mg-doped TiO2 nanoparticles (NPs). The samples were synthesized by sol-gel method and characterized using the standard analytical techniques such as X-ray diffraction (XRD), Transmission electron microscope (TEM), Energy dispersive X-ray spectroscopy (EDX), UV-visible and photoluminescence spectroscopy. The powder XRD spectra revealed that the synthesized samples are pure and crystalline in nature and showing tetragonal anatase phase of TiO2 NPs. UV-visible spectrum illustrates that an absorption edge shifts toward the visible region. This study may provide a new insight for making the nanomaterials which can be used in photocatalytic applications.

  7. Structural and morphological characterization of TiO2 powders prepared using Pechini and combustion reaction

    International Nuclear Information System (INIS)

    Ribeiro, P.C.; Almeida, E.P.; Costa, A.C.F.M. da; Lira, H.L.; Kiminami, R.H.G.A.

    2010-01-01

    TiO 2 is a semiconductor oxide and polymorphic and can exist in three crystallographic forms: anatase, rutile and broquita, and forms anatase and rutile are the major interests in scientific research. Thus, this study aims to synthesize TiO 2 by Pechini methods and combustion reaction and to evaluate the influence of synthesis methods in structural and morphological characteristics of the samples. The nanopowders were characterized by X-ray diffraction, nitrogen adsorption, and particle size distribution and scanning electron microscopy. The results of X-ray diffraction showed that the samples obtained by the Pechini method showed the single phase anatase with crystallite size of 20 nm and surface area of 49.44 m 2 /g, whereas the samples synthesized by combustion reaction using glycine as fuel showed the rutile phase as major phase and traces of anatase phase, with crystallite size of 65 nm and surface area 4.34 m 2 /g. (author)

  8. Morphological study of electrophoretically deposited TiO2 film for DSSC application

    Science.gov (United States)

    Patel, Alkesh B.; Patel, K. D.; Soni, S. S.; Sonigara, K. K.

    2018-05-01

    In the immerging field of eco-friendly and low cost photovoltaic devices, dye sensitized solar cell (DSSC) [1] has been investigated as promising alternative to the conventional silicon-based solar cells. In the DSSC device, photoanode is crucial component that take charge of holding sensitizer on it and inject the electrons from the sensitizer to current collector. Nanoporous TiO2 is the most relevant candidate for the preparation of photoanode in DSSCs. Surface properties, morphology, porosity and thickness of TiO2 film as well as preparation technique determine the performance of device. In the present work we have report the study of an effect of nanoporous anatase titanium dioxide (TiO2) film thickness on DSSC performance. Photoanode TiO2 (P25) film was deposited on conducting substrate by electrophoresis technique (EPD) and film thickness was controlled during deposition by applying different current density for a constant time interval. Thickness and surface morphology of prepared films was studied by SEM and transmittance analysis. The same set of photoanode was utilized in DSSC devices using metal free organic dye sensitizer to evaluate the photovoltaic performance. Devices were characterized through Current-Voltage (I-V) characteristic, electrochemical impedance spectroscopy (EIS) and open circuit voltage decay curves. Dependency of device performance corresponding to TiO2 film thickness is investigated through the lifetime kinetics of electron charge transfer mechanism trough impedance fitting. It is concluded that appropriate thickness along with uniformity and porosity are required to align the dye molecules to respond efficiently the incident light photons.

  9. Rapid photo-degradation of 2-chlorophenol under visible light irradiation using cobalt oxide-loaded TiO2/reduced graphene oxide nanocomposite from aqueous media.

    Science.gov (United States)

    Sharma, Ajit; Lee, Byeong-Kyu

    2016-01-01

    The photocatalytic removal of 2-chlorophenol (2-CP) from water environment was investigated by TiO2-RGO-CoO. Cobalt oxide-loaded TiO2 (TiO2-CoO) supported with reduced graphene oxide (RGO) was synthesized using a sol-gel method and then annealed at 500 °C for 5 min. The material characteristics were analyzed by UV-Vis analysis, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy. Incorporation of cobalt oxide and RGO into the TiO2 system (TiO2-RGO-CoO) lowered the band gap energy to 2.83 eV, which greatly enhanced the visible light absorption. The TiO2-RGO-CoO photocatalyst showed complete removal of 20 mg/L 2-CP within 8 h with the addition of 0.01% H2O2 under 100 W visible light irradiation. The photo-degradation efficiency of 2-CP (10 mg/L) was 35.2, 48.9, 58.9 and 98.2% for TiO2, TiO2-RGO, TiO2-CoO and TiO2-RGO-CoO, respectively, in the presence of visible light irradiation at solution pH of 6.0. The TiO2-RGO-CoO photocatalyst retained its high removal efficiency even after five photocatalytic cycles. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. In Vitro and In Vivo Evaluation of Sol-Gel Derived TiO2 Coatings Based on a Variety of Precursors and Synthesis Conditions

    Directory of Open Access Journals (Sweden)

    Krzysztof Marycz

    2014-01-01

    Full Text Available The effect of synthesis way of TiO2 coatings on biocompatibility of transplanted materials using an in vitro and in vivo rat model was investigated. TiO2 layers were synthesized by a nonaqueous sol-gel dip-coating method on stainless steel 316L substrates applying two different precursors and their combination. Morphology and topography of newly formed biomaterials were determined as well as chemical composition and elemental distribution of a surface samples. In vitro tests were conducted by adipose-derived mesenchymal stem cells cultured on TiO2 coatings and stainless steel without coatings to assess the bioreactivity of obtained materials. A positive biological effect of TiO2/316L/1 coatings—based on titanium(IV ethoxide—was found in both in vitro and in vivo models. The TiO2/316L/1 exhibited the highest roughness and the lowest titanium concentration in TiO2 than TiO2/316L/2—based on titanium(IV propoxide and TiO2/316L/3—based on both above-mentioned precursors. The proper fibroblast-like morphology and higher proliferation rate of cells cultured on TiO2/316L/1 were observed when compared to the other biomaterials. No inflammatory response in the bone surrounding implant covered by each of the obtained TiO2 was present. Our results showed that improvement of routinely used stainless steel 316L with TiO2/316L/1 layer can stimulate beneficial biological response.

  11. Crystallization kinetics of a soda lime silica glass with TiO2 addition

    International Nuclear Information System (INIS)

    De la Parra A, S. M.; Alvarez M, A.; Torres G, L. C.; Sanchez, E. M.

    2009-01-01

    Studies conducted into Na 2 O-CaO-3SiO 2 glass composition suggest that its phase transformation occurs from the surface towards the interior of the sample. In a study carried out in 1982, it was reported that no addition of nucleating agents modified the mechanism. Taking advantage of the disposition materials synthesized by nanotechnology, in this study TiO 2 in nanometer size was used with the idea that, because of its qualities, it could modify the crystallization mechanism. The glasses obtained as well as the thermally treated samples, were evaluated by the X-ray diffraction (XRD) powder method, differential thermal analysis (DTA), and by optical microscopy and high resolution transmission electron microscopy (HRTEM). Within the range of TiO 2 concentration studied (0 - 10 wt %), 10 wt % of TiO 2 considerably reduced the Na 2 O-2CaO-3SiO 2 phase crystallization process. The crystallization mechanism was not modified and TiO 2 did not form compounds with the matrix components. (Author)

  12. Nanoplasmonically Engineered Interfaces on Amorphous TiO2 for Highly Efficient Photocatalysis in Hydrogen Evolution.

    Science.gov (United States)

    Liang, Huijun; Meng, Qiuxia; Wang, Xiaobing; Zhang, Hucheng; Wang, Jianji

    2018-04-25

    The nanoplasmonic metal-driven photocatalytic activity depends heavily on the spacing between metal nanoparticles (NPs) and semiconductors, and this work shows that ethylene glycol (EG) is an ideal candidate for interface spacer. Controlling the synthetic systems at pH 3, the composite of Ag NPs with EG-stabilized amorphous TiO 2 (Ag/TiO 2 -3) was synthesized by the facile light-induced reduction. It is verified that EG spacers can set up suitable geometric arrangement in the composite: the twin hydroxyls act as stabilizers to bind Ag NPs and TiO 2 together and the nonconductive alkyl chains consisting only of two CH 2 are able to separate the two building blocks completely and also provide the shortest channels for an efficient transfer of radiation energies to reach TiO 2 . Employed as photocatalysts in hydrogen evolution under visible light, amorphous TiO 2 hardly exhibits the catalytic activity due to high defect density, whereas Ag/TiO 2 -3 represents a remarkably high catalytic efficiency. The enhancement mechanism of the reaction rate is proposed by the analysis of the compositional, structural, and optical properties from a series of Ag/TiO 2 composites.

  13. TiO_2/WO_3 photoactive bilayers in the UV-Vis light region

    International Nuclear Information System (INIS)

    Vasilaki, E.; Vernardou, D.; Kenanakis, G.; Katsarakis, N.; Vamvakaki, M.

    2017-01-01

    In this work, photoactive bilayered films consisting of anatase TiO_2 and monoclinic WO_3 were synthesized by a sol-gel route. Titanium isopropoxide and tungsten hexachloride were used as metal precursors and deposition was achieved by spin-coating on Corning glass substrates. The samples were characterized by X-ray diffraction, photoluminescence, UV-Vis, and Raman spectroscopy, as well as field emission scanning electron microscopy. The prepared immobilized catalysts were tested for their photocatalytic performance by the decolorization of methylene blue in aqueous matrices, under UV-Vis light irradiation. The annealing process influenced the crystallinity of the bilayered films, while the concentration of the tungsten precursor solution and the position of the tungsten trioxide layer further affected their photocatalytic performance. In particular, the photocatalytic performance of the bilayered films was optimized at a concentration of 0.1 M of the WO_3 precursor solution, when deposited as an overlying layer on TiO_2 by two annealing steps (∝76% methylene blue decolorization in 300 min of irradiation versus ∝59% in the case of a bare TiO_2 film). In general, the coupled layer catalysts exhibited superior photoactivity compared to that of bare TiO_2 films with WO_3 acting as an electron trap, resulting, therefore, in a more efficient electron-hole separation and inhibiting their recombination. (orig.)

  14. BIOSYNTHESIS, CHARACTERIZATION AND APPLICATION OF TIO2 NANOPARTICLES IN BIOCATALYSIS AND PROTEIN FOLDING

    Directory of Open Access Journals (Sweden)

    Razi Ahmad,

    2013-08-01

    Full Text Available The nano-TiO2 was synthesized using Lactobacillus sp. and characterized by XRD and TEM. The X-ray diffraction showed that TiO2 nanoparticles were crystalline in nature. TEM images revealed that these particles are irregular in shape with an average particle size of 50–100 nm. The biosynthesized nanoparticles were used for the immobilization and refolding of thermally inactivated alpha amylase enzyme. The enzyme after adsorption on TiO2 nanoparticles retained 71% of enzyme activity. The immobilized enzyme was found to be thermally more stable as compared to the free enzyme. When the enzyme was heated to 60°C for 60 min the free enzyme loses all of its activity whereas the adsorbed enzyme retained 82% of its activity.The adsorbed/immobilized protein could be reused five times without any loss in enzyme activity. The operational stability data also shows that after immobilization the stability of alpha amylase increases. To study the nanoparticles-protein interaction, alpha amylase enzyme was inactivated by heating at 60°C for 1 hour. The thermally inactivated alpha amylase when incubated with the biosynthesized TiO2 nanoparticles regains nearly 65% activity after 2.0 hour. Thus TiO2 nanoparticles assist in refolding of the enzyme.

  15. Synthesis and characterization of TiO2 nanoparticles by the method Pechini

    International Nuclear Information System (INIS)

    Zoccal, Joao Victor Marques; Arouca, Fabio de Oliveira; Goncalves, Jose Antonio Silveira

    2009-01-01

    In recent years, scientific research showed an increasing interest in the field of nanotechnology, resulting in several techniques for the production of nanoparticles, such as methods of chemical synthesis. Among the various existing methods, the Pechini method has been used to obtain nanoparticles of titanium dioxide (TiO 2 ). Thus, this work aims to synthesize and characterize nanoparticles of TiO 2 obtained by this method. The technique constitutes in the reaction between citric acid with titanium isopropoxide, resulting as the product the titanium citrate. With the addition of the ethylene glycol polymerization occurs, resulting in a polymeric resin. At the end of the process, the resin is calcined to remove organic matter, creating nanoparticles of TiO 2 . The resulting powders were characterized by thermogravimetric analysis (TGA) and thermal differential analysis (DTA), X-ray diffraction, absorption spectrophotometry in the infrared, method of adsorption nitrogen / helium (BET method) and scanning electron microscopy. The results obtained in the characterization techniques showed that the Pechini method is promising in obtaining nanosized TiO 2 . (author)

  16. Development of Nano TiO2–Geopolymer Functional Composite as Antifouling Bricks

    Directory of Open Access Journals (Sweden)

    Kusuma Wardani Nurul

    2017-01-01

    Full Text Available The purpose of study is to examine the ability of nano TiO2 – geopolymer functional composite as antifouling bricks. The samples were synthesized through alkali-activation method at 70°C for 1 hour by mixing metaclay with TiO2 nanoparticles and activated with sodium silicate solution. There were two series of samples produced, namely, GT_A with addition of 2% nanoTiO2 and GT_B with addition of 4% nano TiO2 relative to the mass of metaclay. The samples were immersed in water and in 1M H2SO4 solution for 4 days to examine the resistance of composites in hars environment. The x-ray diffraction (XRD was performed to examine the chemical compositions of the samples before and after environmental test. The morphology of the samples surfaces was examined by using Scanning Electron Microscopy (SEM coupled with energy dispersive spectroscopy (EDS. Based on this study, sample GT_A shows its excellent properties as antifouling bricks. The addition of nano TiO2 was found to improve the quality of geopolymers as a high performance bricks.

  17. Enhanced photocatalytic activity of microwave treated TiO2 pillared montmorillonite

    International Nuclear Information System (INIS)

    Sun Shenmei; Jiang Yinshan; Yu Lixin; Li Fangfei; Yang Zhengwen; Hou Tianyi; Hu Daqiang; Xia Maosheng

    2006-01-01

    TiO 2 pillared montmorillonite synthesized by microwave irradiation, exhibited good photocatalytic degradation performance of methyl orange, whose pseudo first order reaction rate constant was nearly four times than that of conventional method, because of its enhanced crystalline, preferred anatase phase and improved porosity performance, which were analysed by X-ray diffraction (XRD), far Fourier transform infrared ray spectroscopy (FTIR) and nitrogen adsorption isotherms

  18. Preparation of TiO2/boron-doped diamond/Ta multilayer films and use as electrode materials for supercapacitors

    Science.gov (United States)

    Shi, Chao; Li, Hongji; Li, Cuiping; Li, Mingji; Qu, Changqing; Yang, Baohe

    2015-12-01

    We report nanostructured TiO2/boron-doped diamond (BDD)/Ta multilayer films and their electrochemical performances as supercapacitor electrodes. The BDD films were grown on Ta substrates using electron-assisted hot filament chemical vapor deposition. Ti metal layers were deposited on the BDD surfaces by radio frequency magnetron sputtering, and nanostructured TiO2/BDD/Ta thin films were prepared by electrochemical etching and thermal annealing. The successful formation of TiO2 and Ta layered nanostructures was demonstrated using scanning electron and transmission electron microscopies. The electrochemical responses of these electrodes were evaluated by examining their use as electrical double-layer capacitors, using cyclic voltammetry, and galvanostatic charge/discharge and impedance measurements. When the TiO2/BDD/Ta film was used as the working electrode with 0.1 M Na2SO4 as the electrolyte, the capacitor had a specific capacitance of 5.23 mF cm-2 at a scan rate of 5 mV s-1 for a B/C ratio of 0.1% w/w. Furthermore, the TiO2/BDD/Ta film had improved electrochemical stability, with a retention of 89.3% after 500 cycles. This electrochemical behavior is attributed to the quality of the BDD, the surface roughness and electrocatalytic activities of the TiO2 layer and Ta nanoporous structures, and the synergies between them. These results show that TiO2/BDD/Ta films are promising as capacitor electrodes for special applications.

  19. Flexible symmetric supercapacitors based on vertical TiO2 and carbon nanotubes

    Science.gov (United States)

    Chien, C. J.; Chang, Pai-Chun; Lu, Jia G.

    2010-03-01

    Highly conducting and porous carbon nanotubes are widely used as electrodes in double-layer-effect supercapacitors. In this presentation, vertical TiO2 nanotube array is fabricated by anodization process and used as supercapacitor electrode utilizing its compact density, high surface area and porous structure. By spin coating carbon nanotube networks on vertical TiO2 nanotube array as electrodes with 1M H2SO4 electrolyte in between, the specific capacitance can be enhanced by 30% compared to using pure carbon nanotube network alone because of the combination of double layer effect and redox reaction from metal oxide materials. Based on cyclic voltammetry and galvanostatic charge-discharge measurements, this type of hybrid electrode has proven to be suitable for high performance supercapacitor application and maintain desirable cycling stability. The electrochemical impedance spectroscopy technique shows that the electrode has good electrical conductivity. Furthermore, we will discuss the prospect of extending this energy storage approach in flexible electronics.

  20. Influence of anodization parameters on the morphology of TiO 2 nanotube arrays

    Science.gov (United States)

    Omidvar, Hamid; Goodarzi, Saba; Seif, Ahmad; Azadmehr, Amir R.

    2011-07-01

    TiO 2 nanotube arrays can be fabricated by electrochemical anodization in organic and inorganic electrolytes. Morphology of these nanotube arrays changes when anodization parameters such as applied voltage, type of electrolyte, time and temperature are varied. Nanotube arrays fabricated by anodization of commercial titanium in electrolytes containing NH 4F solution and either sulfuric or phosphoric acid were studied at room temperature; time of anodization was kept constant. Applied voltage, fluoride ion concentration, and acid concentrations were varied and their influences on TiO 2 nanotubes were investigated. The current density of anodizing was recorded by computer controlled digital multimeter. The surface morphology (top-view) of nanotube arrays were observed by SEM. The nanotube arrays in this study have inner diameters in range of 40-80 nm.

  1. Physiochemical properties of TiO2 nanoparticle thin films deposited on stainless steel

    Directory of Open Access Journals (Sweden)

    M. Basiaga

    2017-01-01

    Full Text Available The purpose of this study was to evaluate the usefulness of TiO2 layer to improve hemocompatibility of 316LVM stainless steel. The TiO2 layers studied in this work were deposited from TiCl4 and H2O in a low-pressure Atomic Layer Deposition (ALD reactor taking into account number of cycles and process temperature. As a part of the research electrochemical studies of the layer after 28 days exposure to artificial plasma were carried out. In particular, potentiostatic, potentiodynamic and impedance studies were conducted. The obtained results were the basis for selection of surface treatment method dedicated to blood-contacting stainless steel implants.

  2. Synthesis and Characterization of TiO2 Modified with Polystyrene and Poly(3-chloro-2-hydroxypropyl Methacrylate as Adsorbents for the Solid Phase Extraction of Organophosphorus Pesticides

    Directory of Open Access Journals (Sweden)

    Enrique Alejo-Molina

    2016-01-01

    Full Text Available Novel hybrid TiO2 particles were developed and assessed as an adsorbent for solid phase extraction (SPE of organophosphorus pesticides (fensulfothion, parathion methyl, coumaphos, and diazinon from spiked water. The sol-gel method was used to synthesize TiO2 particles, which were coated with free-radical polystyrene (PS and poly(3-chloro-2-hydroxypropyl methacrylate (PClHPMA polymers. Particle structures were determined via Fourier transform infrared spectroscopy to confirm that the polymers were successfully anchored to the TiO2 particles. Thermogravimetric analysis was conducted to determine organic and inorganic matter in TiO2-PS and TiO2-PClHPMA particles showing results of 20 : 80 wt/wt% and 23 : 77 wt/wt%, respectively. SEM-EDS and X-ray diffraction test were conducted to determine the morphology and semielemental composition of the particles showing amorphous characteristics. By observing the contact angle, particles coated with PClHPMA were determined to be more hydrophilic than TiO2-PS particles. The pore size distributions obtained from the N2 adsorption-desorption isotherms were 0.150 and 0.168 cm3g−1. The specific surface area (BET was 239.9 m2g−1 for TiO2-PS and 225.7 m2g−1 for TiO2-PClHPMA. The synthesized particles showed relatively high yields of adsorption in SPE. The pesticide recoveries obtained by high performance liquid chromatography ranged from 6 to 26% for TiO2-PClHPMA and 44 to 92% for TiO2-PS.

  3. Structure and electrochemical hydrogen storage properties of Ti{sub 2}Ni alloy synthesized by ball milling

    Energy Technology Data Exchange (ETDEWEB)

    Hosni, B. [Equipe des Hydrures Métalliques, Laboratoire de Mécanique, Matériaux et Procédés, Ecole Nationale Supérieure d’Ingénieurs de Tunis, ENSIT Ex ESSTT, Université de Tunis, 5 Avenue Taha Hussein, 1008 Tunis (Tunisia); Li, X. [FEMTO-ST, MN2S, Université de Technologie de Belfort-Montbéliard, Site de Sévenans, 90010 Belfort cedex (France); Khaldi, C., E-mail: chokri.khaldi@esstt.rnu.tn [Equipe des Hydrures Métalliques, Laboratoire de Mécanique, Matériaux et Procédés, Ecole Nationale Supérieure d’Ingénieurs de Tunis, ENSIT Ex ESSTT, Université de Tunis, 5 Avenue Taha Hussein, 1008 Tunis (Tunisia); ElKedim, O. [FEMTO-ST, MN2S, Université de Technologie de Belfort-Montbéliard, Site de Sévenans, 90010 Belfort cedex (France); Lamloumi, J. [Equipe des Hydrures Métalliques, Laboratoire de Mécanique, Matériaux et Procédés, Ecole Nationale Supérieure d’Ingénieurs de Tunis, ENSIT Ex ESSTT, Université de Tunis, 5 Avenue Taha Hussein, 1008 Tunis (Tunisia)

    2014-12-05

    Highlights: • The Ti{sub 2}Ni alloy activation requires only one cycle of charge and discharge, regardless of the temperature. • By increasing the temperature the capacity loss, undergoes an increase and it is more pronounced for the 60 °C. • A good correlation is found between the evolutions of the different electrochemical parameters according to the temperature. - Abstract: The structure and the electrochemical hydrogen storage properties of amorphous Ti{sub 2}Ni alloy synthesized by ball milling and used as an anode in nickel–metal hydride batteries were studied. Nominal Ti{sub 2}Ni was synthesized under argon atmosphere at room temperature using a planetary high-energy ball mill. The structural and morphological characterization of the amorphous Ti{sub 2}Ni alloy is carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical characterization of the Ti{sub 2}Ni electrodes is carried out by the galvanostatic charging and discharging, the constant potential discharge, the open circuit potential and the potentiodynamic polarization techniques. The Ti{sub 2}Ni alloy activation requires only one cycle of charge and discharge, regardless of the temperature. The electrochemical discharge capacity of the Ti{sub 2}Ni alloy, during the first eight cycles, and at a temperature of 30 °C, remained practically unchanged and a good held cycling is observed. By increasing the temperature, the electrochemical discharge capacity loss after eight cycles undergoes an increase and it is more pronounced for the temperature 60 °C. At 30 °C, the anodic corrosion current density is 1 mA cm{sup −2} and then it undergoes a rapid drop, remaining substantially constant (0.06 mA cm{sup −2}) in the range 40–60 °C, before undergoing a slight increase to 70 °C (0.3 mA cm{sup −2}). This variation is in good agreement with the maximum electrochemical discharge capacity values found for the

  4. Superior environment resistance of quartz crystal microbalance with anatase TiO2/ZnO nanorod composite films

    International Nuclear Information System (INIS)

    Qiang, Wei; Wei, Li; Shaodan, Wang; Yu, Bai

    2015-01-01

    Graphical abstract: ZnO nanorod array being prepared by an in situ method on the QCM coated with Au film via hydrothermal process and surface modification with coated TiO 2 by sol–gel methods to form a superhydrophobic TiO 2 /ZnO composite film the anatase TiO 2 /ZnO nanorod composite film with a sharp, pencil-like structure exhibiting excellent superhydrophobicity (water contact angle of 155°), non-sticking water properties, and an autonomous cleaning property under UV irradiation. The anatase TiO 2 /ZnO nanorod composite film facilitates the precise measurement and extended lifetime of the QCM for the detection of organic gas molecules. - Highlights: • This work combines, for the first time, the advantage of the TiO 2 /ZnO composite film on photocatalysis and reversible super-hydrophobic and super-hydrophilic transition, and puts forward a solution to satisfy weatherability of quartz crystal microbalance in long-term application. • The anatase TiO 2 /ZnO nanorod composite film with pencil structure exhibit excellent super-hydrophobicity (water contact angle can reach 155°), no-sticking water properties and self-cleaning property under UV irradiation. • The photocatalysis and reversible super-hydrophobic and super-hydrophilic transition of the TiO 2 /ZnO nanorod composite film is stable in long-term application. - Abstract: The precise measurement of quartz crystal microbalance (QCM) in the detection and weighing of organic gas molecules is achieved due to excellent superhydrophobicity of a deposited film composite. Photocatalysis is utilized as a method for the self-cleaning of organic molecules on the QCM for extended long-term stability in the precision of the instrument. In this paper, ZnO nanorod array is prepared via in situ methods on the QCM coated with Au film via hydrothermal process. Subsequently, a TiO 2 /ZnO composite film is synthesized by surface modification with TiO 2 via sol–gel methods. Results show the anatase TiO 2 /ZnO nanorod

  5. Structural and electrochemical analysis of chemically synthesized microcubic architectured lead selenide thin films

    Science.gov (United States)

    Bhat, T. S.; Shinde, A. V.; Devan, R. S.; Teli, A. M.; Ma, Y. R.; Kim, J. H.; Patil, P. S.

    2018-01-01

    The present work deals with the synthesis of lead selenide (PbSe) thin films by simple and cost-effective chemical bath deposition method with variation in deposition time. The structural, morphological, and electrochemical properties of as-deposited thin films were examined using characterization techniques such as X-ray diffraction spectroscopy (XRD), field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy. XRD reveals formation of rock salt phase cubic structured PbSe. FE-SEM images show the formation of microcubic structured morphology. The existence of the PbSe is confirmed from the XPS analysis. On the other hand, CV curves show four reaction peaks corresponding to oxidation [PbSe and Pb(OH)2] and reduction (PbO2 and Pb(OH)2) at the surface of PbSe thin films. The PbSe:2 sample deposited for 80 min. shows maximum specific capacitance of 454 ± 5 F g- 1 obtained at 0.25 mA cm- 2 current density. The maximum energy density of 69 Wh kg- 1 was showed by PbSe:2 electrode with a power density of 1077 W kg- 1. Furthermore, electrochemical impedance studies of PbSe:2 thin film show 80 ± 3% cycling stability even after 500 CV cycles. Such results show the importance of microcubic structured PbSe thin film as an anode in supercapacitor devices.

  6. Electrochemical behaviour of ceramic yttria stabilized zirconia on carbon steel synthesized via sol-gel process

    International Nuclear Information System (INIS)

    Crespo, M.A. Dominguez; Murillo, A. Garcia; Torres-Huerta, A.M.; Yanez-Zamora, C.; Carrillo-Romo, F. de J

    2009-01-01

    Chromate conversion coatings have been widely applied for the corrosion of different metallic substrates. However, the waste containing Cr 6+ has many limitations due to the environmental consideration and health hazards. An interesting alternative seems to be the deposition on metallic surface of thin layers of yttria or zirconia or both by the sol-gel process. In this study, Ytttria and Yttria stabilized zirconia (YSZ, 8% Y 2 O 3 ) thin films were used for coating commercial carbon steel substrates by sol-gel method and the dip-coating process. The evolution of organic compounds up to crystallization process as a function of heat treatments was study by FT-IR spectroscopy. The structure and morphology of the coatings were analysed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The anticorrosion performance of the coatings has been evaluated by using electrochemical techniques in an aggressive media (3.5 wt.% NaCl). The corrosion behaviour of sol-gel method was compared with traditional chromate conversion coatings. Differences in the electrochemical behaviour of YSZ coatings are related to the development of microcracks during the sintering process and to the presence of organic compounds during growth film. Electrochemical results showed that sol-gel YSZ and Y 2 O 3 coatings can act as protective barriers against wet corrosion; however yttria films displayed low adhesion to substrate. The corrosion parameters provide an explanation of the role of each film and show a considerable increase in the corrosion resistance for coated samples in comparison to the bare steel samples.

  7. Electrochemical behaviour of ceramic yttria stabilized zirconia on carbon steel synthesized via sol-gel process

    Energy Technology Data Exchange (ETDEWEB)

    Crespo, M.A. Dominguez, E-mail: mdominguezc@ipn.m [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Unidad Altamira (CICATA-IPN) km 14.5 Carr. Tampico-Puerto Industrial, C.P. 89600, Altamira, Tamaulipas (Mexico); Murillo, A. Garcia; Torres-Huerta, A.M. [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Unidad Altamira (CICATA-IPN) km 14.5 Carr. Tampico-Puerto Industrial, C.P. 89600, Altamira, Tamaulipas (Mexico); Yanez-Zamora, C. [Estudiante del postgrado en Tecnologia Avanzada del CICATA-IPN, Unidad Altamira, km 14.5, Carr. Tampico-Puerto Industrial. C.P. 89600, Altamira, Tamaulipas (Mexico); Carrillo-Romo, F. de J [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Unidad Altamira (CICATA-IPN) km 14.5 Carr. Tampico-Puerto Industrial, C.P. 89600, Altamira, Tamaulipas (Mexico)

    2009-08-26

    Chromate conversion coatings have been widely applied for the corrosion of different metallic substrates. However, the waste containing Cr{sup 6+} has many limitations due to the environmental consideration and health hazards. An interesting alternative seems to be the deposition on metallic surface of thin layers of yttria or zirconia or both by the sol-gel process. In this study, Ytttria and Yttria stabilized zirconia (YSZ, 8% Y{sub 2}O{sub 3}) thin films were used for coating commercial carbon steel substrates by sol-gel method and the dip-coating process. The evolution of organic compounds up to crystallization process as a function of heat treatments was study by FT-IR spectroscopy. The structure and morphology of the coatings were analysed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The anticorrosion performance of the coatings has been evaluated by using electrochemical techniques in an aggressive media (3.5 wt.% NaCl). The corrosion behaviour of sol-gel method was compared with traditional chromate conversion coatings. Differences in the electrochemical behaviour of YSZ coatings are related to the development of microcracks during the sintering process and to the presence of organic compounds during growth film. Electrochemical results showed that sol-gel YSZ and Y{sub 2}O{sub 3} coatings can act as protective barriers against wet corrosion; however yttria films displayed low adhesion to substrate. The corrosion parameters provide an explanation of the role of each film and show a considerable increase in the corrosion resistance for coated samples in comparison to the bare steel samples.

  8. Influence of different types of nanomaterials on their bioaccumulation in a paddy microcosm: A comparison of TiO2 nanoparticles and nanotubes

    International Nuclear Information System (INIS)

    Yeo, Min-Kyeong; Nam, Dong-Ha

    2013-01-01

    We investigated the environmental fate and bioaccumulation of TiO 2 nanomaterials in a simplified paddy microcosm over a period of 17 days. Two types of TiO 2 nanomaterials, nanoparticles (TiO 2 -NP) and nanotubes (TiO 2 -NT), were synthesized to have a negative surface charge. Ti concentrations in the environmental media (water, soil), crops (quillworts, water dropworts), and some lower and higher trophic organisms (biofilms, algae, plant-parasitic nematodes, white butterfly larva, mud snail, ricefish) were quantified after exposure periods of 0, 7, and 17 days. The titanium levels of the two nanomaterials were the highest in biofilms during the exposure periods. Bioaccumulation factors indicated that TiO 2 -NP and TiO 2 -NT were largely transferred from a prey (e.g., biofilm, water dropwort) to its consumer (e.g., nematodes, mud snail). Considering the potential entries of such TiO 2 nanomaterials in organisms, their bioaccumulation throughout the food chain should be regarded with great concern in terms of the overall health of the ecosystem. -- Highlights: •A high amount of nanomaterial was transferred within low trophic level organisms. •Nanomaterial transfer occurred from water dropwort roots to nematodes and snails. •Nanomaterial transfer occurred from the biofilm-consuming plankton to ricefish. •TiO 2 nanomaterials can accumulate in the organisms of an artificial ecosystem. -- TiO 2 nanomaterials can accumulate in the organisms of an artificial ecosystem

  9. Development of a Low-Cost TiO2/CuO/Cu Solar Cell by using Combined Spraying and Electroplating Method

    Directory of Open Access Journals (Sweden)

    Mamat Rokhmat

    2018-03-01

    Full Text Available A simple method is proposed to develop a low-cost TiO2/CuO/Cu based solar cell. The cell is made by employing a lower grade (technical grade of TiO2 as the active material. CuO powder is synthesized using a wet chemical method and mixed with TiO2 powder to give impurity to the TiO2. A layer of TiO2/CuO is then deposited onto fluorin-doped tin oxide (FTO by spraying. Copper particles are grown on the spaces between the TiO2 and/or CuO particles by electroplating for more feasible electron migration. The TiO2/CuO/Cu solar cell is finalized by sandwiching a polymer electrolyte between the film and the counter electrode. Current-voltage measurement was performed for various parameters, such as the molarity of NaOH for producing CuO particles, the weight ratio of CuO over TiO2, and the current in the electroplating process. A highest efficiency of 1.40% and a fill factor of 0.37 were achieved by using this combined spray and electroplating method.

  10. Synthesis of ascorbic acid enhanced TiO2 photocatalyst: its characterization and catalytic activity in CO2 photoreduction

    Directory of Open Access Journals (Sweden)

    Mohd Farid Bin Mohd Na'aim

    2018-04-01

    Full Text Available To date, the development of solar environmental remediation has shifted more emphasis on the green and simple synthesis of catalyst for CO2 photocatalysis process. Herein, TiO2 photocatalyst was successfully synthesized via hydrothermal method. The effects of the different molar ratio of ascorbic acid C6H8O6, (AA added during the preparation of TiO2 nanoparticles were comprehensively studied. The characterization of TiO2 nanocrystals was performed via XRD, XPS, DRUV-vis, and FTIR. The results show the AA loading into TiO2 nanoparticles significantly intensified the XRD spectra of anatase structure. In fact, this feature had signified a reactivity of the photocatalyst in the visible region. In an instance, BET surface area was also enhanced with the highest recorded value of 135.14 m2/g for 0.8AA. Meanwhile, the CO2 photoreduction over synthesized TiO2 had produced the highest amount of HCOOH at 39.3 μmol/g cat for 0.8AA within 6 hours of reaction time. Furthermore, the DRUV-vis analysis had illustrated better light absorption ability of 0.8AA. This profound finding is attributed to the correlation between large surface area, pure anatase phase, and high adsorbed water molecules. Therefore, this study had significantly demonstrated the potential of modified TiO2 with AA in CO2 photocatalysis area while simultaneously presents a green and simple method for TiO2 synthesis.

  11. Photodegradation of rhodamine B and methyl orange over one-dimensional TiO2 catalysts under simulated solar irradiation

    International Nuclear Information System (INIS)

    Guo Changsheng; Xu Jian; He Yan; Zhang Yuan; Wang Yuqiu

    2011-01-01

    In this paper, two one-dimensional (1D) TiO 2 nanostructures, nanotube and nanowire were synthesized by a hydrothermal method using Degussa P25 TiO 2 as a precursor. The synthesized anatase TiO 2 nanotubes with the diameters of 10-20 nm and length of several hundred nanometers were formed from P25 and NaOH with the hydrothermal treatment temperature at 150 deg. C, and anatase TiO 2 nanowires with the diameters of 10-40 nm and length up to several micrometers were prepared at 180 deg. C. The photocatalytic activity of the two nanostructures was evaluated by degrading rhodamine B (RhB) and methyl orange (MO) in aqueous solutions under simulated solar light irradiation. The results suggested that the TiO 2 nanocatalysts displayed higher degradation activity compared to P25. For RhB, 98.9% and 91.9% of RhB were removed by nanotubes and nanowires, respectively after 60 min irradiation in comparison to the 81.8% removal by P25. Similar trend was observed for MO, with the removal percentage of 95.6%, 88.3% and 74.9%, respectively by TiO 2 nanotubes, nanowires and P25. Meanwhile, RhB and MO showed different photodegradation rates in nanotubes and nanowires suspensions, probably due to the morphology and crystal structure of the TiO 2 nanocatalysts which play important roles in the degradation activity of the catalysts.

  12. Synthesis of carbon-coated TiO 2 nanotubes for high-power lithium-ion batteries

    Science.gov (United States)

    Park, Sang-Jun; Kim, Young-Jun; Lee, Hyukjae

    Carbon-coated TiO 2 nanotubes are prepared by a simple one-step hydrothermal method with an addition of glucose in the starting powder, and are characterized by morphological analysis and electrochemical measurement. A thin carbon coating on the nanotube surface effectively suppresses severe agglomeration of TiO 2 nanotubes during hydrothermal reaction and post calcination. This action results in better ionic and electronic kinetics when applied to lithium-ion batteries. Consequently, carbon-coated TiO 2 nanotubes deliver a remarkable lithium-ion intercalation/deintercalation performance, such as reversible capacities of 286 and 150 mAh g -1 at 250 and 7500 mA g -1, respectively.

  13. Effects of Hydroxylation on PbS Quantum Dot Sensitized TiO2 Nanotube Array Photoelectrodes

    International Nuclear Information System (INIS)

    Liu, Zhongqing; Wang, Bin; Wu, Jianchun; Dong, Qiang; Zhang, Xiaoming; Xu, He

    2016-01-01

    ABSTRACT: The contact state at the heterojunction interfaces greatly influences the interfacial kinetics of the photoinduced charge carriers. In this study, we used a facile NaOH pretreatment to replenish the hydroxyl groups lost during the heat treatment for crystallization of TiO 2 nanotube arrays (TNAs) prepared via anodic oxidization. By reacting the carboxylic acid groups of thioglycolic acid (TGA) with the TiO 2 surface hydroxyl groups, TGA molecules were covalently linked to the TiO 2 surface and then PbS quantum dots (QDs) were anchored onto the TNAs via the successive ionic layer adsorption and reaction (SILAR) method. The sample microstructure and photoelectrochemical properties were analyzed with X-ray diffraction (XRD), transmission electron microscopy (TEM), field-emission scanning electron microscopy (FE-SEM),current–voltage characteristics (J–V), electrochemical impedance spectroscopy (EIS), transient photovoltage plots and Mott-Schottky curves. The contact state and electrostatic potential distribution between TiO 2 {1 0 1} and PbS {1 1 1} planes were estimated by using first principle simulation. It was found that the NaOH pretreatment could enhance the crystallization degree of PbS QDs, decrease the crystal face mismatch, dangling bond density and the interfacial resistance between PbS QDs and TiO 2 , and accelerate the interfacial separation and transfer of photoinduced charge carriers. The first principle calculations demonstrated that the PbS QDs and TiO 2 interfacial contact was strengthened, and the built-in electric field was induced from TiO 2 {1 0 1} towards PbS {1 1 1}. These combined effects apparently improved the device photoelectrochemical performance. Compared to the sample without pretreatment, the specimen pretreated with NaOH demonstrated 19.96% and 29.93% increases in peak photoconversion efficiency after five and ten cycles of SILAR deposition, respectively.

  14. CeO2-TiO2 Photocatalyst: Ionic Liquid-Mediated Synthesis, Characterization, and Performance for Diisopropanolamine Visible Light Degradation

    Directory of Open Access Journals (Sweden)

    Jagath Retchahan Sivalingam

    2018-01-01

    Full Text Available CeO2-TiO2 photocatalyst with Ce:Ti molar ratio of 1:9 was synthesized via co-precipitation method in the presence of 1-ethyl-3-methyl imidazolium octylsulfate, [EMIM][OctSO4] (CeO2-TiO2-IL. The ionic liquid acts as a templating agent for particle growth. The CeO2-TiO2 and TiO2 photocatalysts were also synthesized without any ionic liquid for comparison. Calcination was conducted on the as-synthesized materials at 400˚C for 2 h. The photocatalysts were characterized using diffuse reflectance UV-Vis spectroscopy (DR-UV-Vis, field emission scanning electron microscopy (FESEM, X-ray powder diffraction (XRD, and surface area and pore size analyzer (SAP. The presence of CeO2 has changed the optical property of TiO2. It has extended the absorption edge of TiO2 from UV to visible region. The calculated band gap energy decreased from 2.82 eV (TiO2 to 2.30 eV (CeO2-TiO2-IL. The FESEM morphology showed that samples forms aggregates and the surface smoothens when ionic liquid was added. The average crystallite size of TiO2, CeO2-TiO2, and CeO2-TiO2-IL were 20.8 nm, 5.5 nm, and 4 nm. In terms of performance, photodegradation of 1000 ppm of diisopropanolamine (DIPA was conducted in the presence of hydrogen peroxide (H2O2 and visible light irradiation which was provided by a 500 W halogen lamp. The best performance was displayed by CeO2-TiO2-IL calcined at 400˚C. It was able to remove 82.0% DIPA and 54.8% COD after 6 h reaction.  Copyright © 2018 BCREC Group. All rights reserved Received: 26th July 2017; Revised: 22nd October 2017; Accepted: 29th October 2017; Available online: 22nd January 2018; Published regularly: 2nd April 2018 How to Cite: Sivalingam, J.R., Kait, C.F., Wilfred, C.D. (2018. CeO2-TiO2 Photocatalyst: Ionic Liquid-Mediated Synthesis, Characterization, and Performance for Diisopropanolamine Visible Light Degradation. Bulletin of Chemical Reaction Engineering & Catalysis, 13 (1: 170-178 (doi:10.9767/bcrec.13.1.1396.170-178

  15. Controlled Directional Growth of TiO2 Nanotubes

    DEFF Research Database (Denmark)

    In, Su-il; Hou, Yidong; Abrams, Billie

    2010-01-01

    We demonstrate how the anodization direction and growth rate of vertically aligned, highly ordered TiO2 nanotube (NT) arrays can be controlled and manipulated by the local concentration of O-2 in the electrolyte. This leads to the growth of highly active TiO2 NT arrays directly on nonconducting s...

  16. Silicon protected with atomic layer deposited TiO2

    DEFF Research Database (Denmark)

    Seger, Brian; Tilley, S. David; Pedersen, Thomas

    2013-01-01

    The present work demonstrates that tuning the donor density of protective TiO2 layers on a photocathode has dramatic consequences for electronic conduction through TiO2 with implications for the stabilization of oxidation-sensitive catalysts on the surface. Vacuum annealing at 400 °C for 1 hour o...

  17. Preparation, characterization and photocatalytic activity of TiO2 ...

    Indian Academy of Sciences (India)

    Photocatalyst; TiO2 nanoparticle; polyaniline; conducting polymer; core-shell nanocomposite. 1. Introduction ..... tine TiO2 nanoparticles, HCl-doped PANI and PANI/TiO2 ..... Karim M R, Lim K T, Lee M S, Kim K and Yeum J H 2009 Synth. Met.

  18. Preparation of micro/nanostructure TiO2 spheres by controlling pollen as hard template and soft template.

    Science.gov (United States)

    Yang, Xiaohui; Xu, Bin; Zhang, Xuehong; Song, Xiuqin; Chen, Rufen

    2014-09-01

    In this paper, micro/nanostructure TiO2 spheres were synthesized by a sunflower pollen induced and self-assembly mineralization process, in which a titania precursor and pollen reacted in one-pot at normal pressure. In this paper, the bio-template advantage, as hard and soft template is fully demonstrated. The superiority of our synthesis is that we not only can control pollen as hard template, but also can control it as soft template only by changing reactions temperature. Under 80 degrees C of water bath, TiO2 microspheres which replicated the morphology of pollen were prepared by controlling pollen as hard template. Under 100 degrees C, hierarchical TiO2 spheres with complicated morphology, different from pollen template, were synthesized by using pollen as soft template. At the same time, judicious choice of the amount of pollen affords the synthesis of hierarchical structures spheres with adjustable morphology and crystal structure. The morphology can be tuned from microspheres constructed from TiO2 nanorods to nanospheres constructed from TiO2 nanoparticles, and the crystal structure can be tuned from rutile to anatase. More over this anatase phase can be keep better even at high temperature of 1000 degrees C. The as-prepared micro/nano structure photocatalysts not only have high photocatalytic activities, but also have good separability and reuse performance.

  19. Development of high efficient visible light-driven N, S-codoped TiO2 nanowires photocatalysts

    Science.gov (United States)

    Zhang, Yanlin; Liu, Peihong; Wu, Honghai

    2015-02-01

    One-dimensional (1D) nanowire material (especially nonmetal doped 1D nanowires) synthesized by a facile way is of great significance and greatly desired as it has higher charge carrier mobility and lower carrier recombination rate. N, S-codoped TiO2 nanowires were synthesized using titanium sulfate as a precursor and isopropanol as a protective capping agent by a hydrothermal route. The obtained doped nanowires were characterized by XRD, SEM, HRTEM, SAED, XPS, BET and UV-vis absorption spectrum. The incorporation of N and S into TiO2 NWs can lead to the expansion of its lattice and remarkably lower its electron-transfer resistance. Photocatalytic activity measurement showed that the N, S-codoped TiO2 nanowires with high quantum efficiency revealed the best photocatalytic performance for atrazine degradation under visible light irradiation compared to N, S-codoped TiO2 nanoparticles and S-doped TiO2 nanowires, which was attributed to (i) the synergistic effect of N and S doping in narrowing the band gap, separating electron-hole pairs and increasing the photoinduced electrons, and (ii) extending the anatase-to-rutile transformation temperature above 600 °C.

  20. Facile preparation of a TiO2 quantum dot/graphitic carbon nitride heterojunction with highly efficient photocatalytic activity

    Science.gov (United States)

    Wang, Xing; Jiang, Subin; Huo, Xuejian; Xia, Rui; Muhire, Elisée; Gao, Meizhen

    2018-05-01

    In this article, mechanical grinding, an effortless and super-effective synthetic strategy, is used to successfully synthesize a TiO2 quantum dot (TiO2QD)/graphitic carbon nitride (g-C3N4) heterostructure. X-ray photoelectron spectroscopy results together with transmission electron microscopy reveal the formation of the TiO2QD/g-C3N4 heterostructure with strong interfacial interaction. Because of the advantages of this characteristic, the prepared heterostructure exhibits excellent properties for photocatalytic wastewater treatment. Notably, the optimum photocatalytic activity of the TiO2QD/g-C3N4 heterostructure is nearly 3.4 times higher than that of the g-C3N4 nanosheets used for the photodegradation of rhodamine B pollutant. In addition, the stability and possible degradation mechanism of the TiO2QD/g-C3N4 heterojunction are studied in detail. This method may stimulate an effective approach to synthesizing QD-sensitized semiconductor materials and facilitate their application in environmental protection.

  1. Self-Assembly of TiO2/CdS Mesoporous Microspheres with Enhanced Photocatalytic Activity via Hydrothermal Method

    Directory of Open Access Journals (Sweden)

    Sujing Yu

    2014-01-01

    Full Text Available Self assembly of TiO2/CdS mesoporous microspheres was synthesized via hydrothermal method. The samples were characterized by X-ray powder diffraction (XRD, ultraviolet-visible diffuse reflectance spectroscopy (DRS, transmission electron microscopy (TEM, energy-dispersive spectroscopy analysis (EDS, high-resolution transmission electron microscopy (HRTEM, Brunauer-Emmett-Teller (BET, X-ray photoelectron spectroscopy (XPS, and photoluminescence spectra (PL. The as-synthesized TiO2/CdS mesoporous microspheres showed superior photocatalytic activity for the degradation of RhB under either visible light or simulated sunlight irradiation; the 10 wt% TiO2/CdS sample showed the best performance. Moreover, this catalyst showed improved stability, and the activity did not decrease significantly after four recycles. The heterojunction between TiO2 and CdS may be favorable for the transport of photoinduced electrons from CdS to TiO2. In addition, the mesoporous structure could increase the utilization of light energy and facilitate the diffusion of reactants and products during the photocatalytic reaction.

  2. Performance of electrodes synthesized with polyacrylonitrile-based carbon nanofibers for application in electrochemical sensors and biosensors.

    Science.gov (United States)

    Adabi, Mahdi; Saber, Reza; Faridi-Majidi, Reza; Faridbod, Farnoush

    2015-03-01

    The purpose of this work was to investigate the performance of electrodes synthesized with Polyacrylonitrile-based carbon nanofibers (PAN-based CNFs). The homogenous PAN solutions with different concentrations were prepared and electrospun to acquire PAN nanofibers and then CNFs were fabricated by heat treatment. The effective parameters for the production of electrospun CNF electrode were investigated. Scanning electron microscopy (SEM) was used to characterize electrospun nanofibers. Cyclic voltammetry was applied to investigate the changes of behavior of electrospun CNF electrodes with different diameters. The structure of CNFs was also evaluated via X-ray diffraction (XRD) and Raman spectroscopy. The results exhibited that diameter of nanofibers reduced with decreasing polymer concentration and applied voltage and increasing tip-to-collector distance, while feeding rate did not have significant effect on nanofiber diameter. The investigations of electrochemical behavior also demonstrated that cyclic voltammetric response improved as diameter of CNFs electrode decreased. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Layer-by-Layer Motif Architectures: Programmed Electrochemical Syntheses of Multilayer Mesoporous Metallic Films with Uniformly Sized Pores.

    Science.gov (United States)

    Jiang, Bo; Li, Cuiling; Qian, Huayu; Hossain, Md Shahriar A; Malgras, Victor; Yamauchi, Yusuke

    2017-06-26

    Although multilayer films have been extensively reported, most compositions have been limited to non-catalytically active materials (e.g. polymers, proteins, lipids, or nucleic acids). Herein, we report the preparation of binder-free multilayer metallic mesoporous films with sufficient accessibility for high electrocatalytic activity by using a programmed electrochemical strategy. By precisely tuning the deposition potential and duration, multilayer mesoporous architectures consisting of alternating mesoporous Pd layers and mesoporous PdPt layers with controlled layer thicknesses can be synthesized within a single electrolyte, containing polymeric micelles as soft templates. This novel architecture, combining the advantages of bimetallic alloys, multilayer architectures, and mesoporous structures, exhibits high electrocatalytic activity for both the methanol oxidation reaction (MOR) and the ethanol oxidation reaction (EOR). © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Structural, Electrical and Optical Properties of TiO2 Thin Film Deposited on the Nano Porous Silicon Template

    Science.gov (United States)

    Bahar, Mahmood; Dermani, Ensieh Khalili

    The porous silicon (PSi), which is produced by the electrochemical etching, has been used as a substrate for the growth of the titanium oxide (TiO2) thin films. By using the EBPVD method, TiO2 thin films have been deposited on the surface of the PSi substrate. TiO2/PSi layers were annealed at the temperature of 400∘C, 500∘C and 600∘C for different tests. The morphology and structures of layers were investigated by the scanning electron microscopy (SEM) and X-ray diffraction (XRD). The current-voltage characteristic curves of samples and the ideality factor of heterojunction were studied. The results showed that the electrical properties of the samples change with increase in the annealing temperature. The optical properties of the prepared samples were investigated by using UV-Vis and photoluminescence (PL) spectroscopy. Green light emission of the PSi combined with the blue light and violet-blue emission obtained from the TiO2/PSi PL spectra. The results showed that the optical band gap energy of the PSi has increased from 1.86eV to 2.93eV due to the deposition of TiO2 thin film.

  5. Fast fabrication of long TiO2 nanotube array with high photoelectrochemical property on flexible stainless steel.

    Science.gov (United States)

    Tao, Jie; Wu, Tao; Gao, Peng

    2012-03-01

    Oriented highly ordered long TiO2 nanotube array films with nanopore structure and high photoelectrochemical property were fabricated on flexible stainless steel substrate (50 microm) by anodization treatment of titanium thin films in a short time. The samples were characterized by means of field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and photoelectrochemical methods, respectively. The results showed that Ti films deposited at the condition of 0.7 Pa Ar pressure and 96 W sputtering power at room temperature was uniform and dense with good homogeneity and high crystallinity. The voltage and the anodization time both played significant roles in the formation of TiO2 nanopore-nanotube array film. The optimal voltage was 60 V and the anodization time is less than 30 min by anodizing Ti films in ethylene glycerol containing 0.5% (w) NH4F and 3% (w) H2O. The growth rate of TiO2 nanotube array was as high as 340 nm/min. Moreover, the photocurrent-potential curves, photocurrent response curves and electrochemical impedance spectra results indicated that the TiO2 nanotube array film with the nanoporous structure exhibited a better photo-response ability and photoelectrochemical performance than the ordinary TiO2 nanotube array film. The reason is that the nanoporous structure on the surface of the nanotube array can separate the photo electron-hole pairs more efficiently and completely than the tubular structure.

  6. Electrical characterization of TiO{sub 2} nanotubes synthesized through electrochemical anodizing method

    Energy Technology Data Exchange (ETDEWEB)

    Manescu, Veronica; Paltanea, Gheorghe; Popovici, Dorina [POLITEHNICA University from Bucharest, Electrical Engineering Department, 313 Splaiul Independentei, Bucharest (Romania); Jiga, Gabriel [POLITEHNICA University from Bucharest, Strength of Materials Department, 313 Splaiul Independentei, Bucharest (Romania)

    2016-05-18

    In the present paper, the electrochemical anodizing method was used for the obtaining of TiO{sub 2} nanotube layers, developed on titanium surface. Self-organized titanium nanotubes were obtained when an aqueous solution of 49.5 wt % H{sub 2}O – 49.5 wt % glycerol – 1 wt % HF was used as electrolyte, the anodizing time being equal to 8 hours and the applied voltage to 25 V. Scanning electron microscopy shows that the one-dimensional nanostructure has a tubular configuration with an inner diameter of approximately 60 nm and an outer diameter of approximately 100 nm. The electrical properties of these materials were analyzed through dielectric spectroscopy method.

  7. Binary iron sulfides as anode materials for rechargeable batteries: Crystal structures, syntheses, and electrochemical performance

    Science.gov (United States)

    Xu, Qian-Ting; Li, Jia-Chuang; Xue, Huai-Guo; Guo, Sheng-Ping

    2018-03-01

    Effective utilization of energy requires the storage and conversion device with high ability. For well-developed lithium ion batteries (LIBs) and highly developing sodium ion batteries (SIBs), this ability especially denotes to high energy and power densities. It's believed that the capacity of a full cell is mainly contributed by anode materials. So, to develop inexpensive anode materials with high capacity are meaningful for various rechargeable batteries' better applications. Iron is a productive element in the crust, and its oxides, sulfides, fluorides, and oxygen acid salts are extensively investigated as electrode materials for batteries. In view of the importance of electrode materials containing iron, this review summarizes the recent achievements on various binary iron sulfides (FeS, FeS2, Fe3S4, and Fe7S8)-type electrodes for batteries. The contents are mainly focused on their crystal structures, synthetic methods, and electrochemical performance. Moreover, the challenges and some improvement strategies are also discussed.

  8. Electrochemical performance of Si@TiN composite anode synthesized in a liquid ammonia for lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Tu, Jiguo; Wang, Wei [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Jiao, Shuqiang, E-mail: sjiao@ustb.edu.cn [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Hou, Jungang; Huang, Kai [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Zhu, Hongmin, E-mail: hzhu@metall.ustb.edu.cn [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China)

    2012-10-15

    High-efficiency Si@TiN composite anode was synthesized by a homogeneous reduction reaction in the liquid ammonia, then calcinated at 950 Degree-Sign C for 2 h in vacuum. The crystal structure and morphology of the obtained in-situ coated composites were characterized by XRD, FESEM. The results showed that the micron-sized Si particles were almost coated by the TiN nanoparticles with the average size of 50 nm, while the morphology of Si@TiN composite was almost unchanged over 50 discharge-charge cycles. The electrochemical performances of Si@TiN composite anode were studied by galvanostatic discharge-charge tests, cyclic voltammetry (CV) and electrochemical impedance spectrum (EIS). The CV curves showed that the two redox peaks remained stable and were attributed to the alloying/dealloying process of Li with active Si particles. It could be seen from the EIS curves that the charge transfer resistance (R{sub ct}) for fresh was larger than that for the 50th cycle, which was mainly because the electrons and Li ions conducted on the electrode surface more difficultly for fresh. The cycle stability of the as-prepared Si@TiN composite anode was investigated, with the result showing that the cycling performance was stable and optimal at a rate of 0.2 C. The initial charge capacity was as high as 3226.99 mAh g{sup -1}, which was kept as 467.02 mAh g{sup -1} over 50 cycles. -- Highlights: Black-Right-Pointing-Pointer Si@TiN composite anode was synthesized in-situ in a liquid ammonia. Black-Right-Pointing-Pointer The size of TiN nanoparticles was about 50 nm. Black-Right-Pointing-Pointer The initial charge capacity was as high as 3226.99 mAh g{sup -1}.

  9. Structure and electrochemical properties of Mg2SnO4 nanoparticles synthesized by a facile co-precipitation method

    International Nuclear Information System (INIS)

    Tang, Hao; Cheng, Cuixia; Yu, Gaige; Liu, Haowen; Chen, Weiqing

    2015-01-01

    Nanosized Mg 2 SnO 4 has been synthesized by a facile co-precipitation method. The structure and morphology of the as-prepared samples are characterized by X-ray diffraction (XRD), X-ray photoelectron spectrometer (XPS), fourier Transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). It is found that Mg 2 SnO 4 sample is very sensitive to the aging time of the precursor. The single phase Mg 2 SnO 4 nanoparticles with ∼23 nm can be obtained at 900 °C using the aging 35 min percusor as source. The electrochemical properties of the powder obtained at 900 °C are investigated by galvanostatic discharge-charge tests and cyclic voltammograms (CVs). The initial specific discharge capacity reaches as high as 927.7 mAh g −1 at 0.2 mA cm −2 in 0.05–3.0 V, which indicates that Mg 2 SnO 4 nanoparticles could be a promising candidate of anode material for Li-ion batteries. - Highlights: • Nanosized Mg 2 SnO 4 has been synthesized by a facile co-precipitation method. • We find that Mg 2 SnO 4 sample is very sensitive to the ageing time of the precursor. • The single phase Mg 2 SnO 4 nanoparticles with about 23 nm can be obtained by calcining the ageing 35 min percusor at 900 °C. • The obtained powders show a better electrochemical performance

  10. Dielectric response and room temperature ferromagnetism in Cr doped anatase TiO2 nanoparticles

    Science.gov (United States)

    Naseem, Swaleha; Khan, Wasi; Khan, Shakeel; Husain, Shahid; Ahmad, Abid

    2018-02-01

    In the present work, nanocrystalline samples of Ti1-xCrxO2 (x = 0, 0.02, 0.04, 0.06 and 0.08) were synthesized in anatase phase through simple and cost effective acid modified sol gel method. The influence of Cr doping on thermal, microstructural, electrical and magnetic properties was investigated in TiO2 host matrix. The surface morphology has revealed less agglomeration and considerable reduction in particle size in case of Cr doped TiO2 as compared to undoped TiO2 nanoparticles (NPs). Energy dispersive x-ray spectroscopy (EDS), Raman and X-ray photoelectron spectroscopy (XPS) established high purity, appropriate stoichiometry and oxidation states of the compositions. The dielectric properties of the nanoparticles were altered by the doping concentration, applied frequency as well as temperature variation. The variation in dielectric constant (ε‧), dielectric loss (δ) and ac conductivity as a function of frequency and temperature at different doping concentration of Cr were interpreted in the light of Maxwell Wagner theory, space charge polarization mechanism and drift mobility of charge carriers. Both undoped and Cr doped TiO2 samples exhibit room temperature ferromagnetism (RTFM) that remarkably influenced by means of the Cr content. The significant enhancement in the magnetization was observed at 4% Cr doping. However, decrease in magnetization for higher doping signify antiferromagnetic interactions between Cr ions or superexchange mechanism. These results reveal that the oxygen vacancies play a crucial role to initiate the RTFM. Therefore, the present investigation suggests the potential applications of Cr doped TiO2 nanoparticles for spintronics application.

  11. Uniformly distributed anatase TiO2 nanoparticles on graphene: Synthesis, characterization, and photocatalytic application

    International Nuclear Information System (INIS)

    Bai, Xue; Zhang, Xiaoyuan; Hua, Zulin; Ma, Wenqiang; Dai, Zhangyan; Huang, Xin; Gu, Haixin

    2014-01-01

    Highlights: • Uniform distributed TiO 2 nanoparticles on graphene by a modified method. • Reduced recombination rate of photogenerated electron–hole pairs. • Effective charge transfer from TiO 2 to graphene. • Better photocatalytic activity upon UV and visible irradiation. • A mechanism of bisphenol A degradation process is proposed. - Abstract: Graphene (GR)/TiO 2 nanocomposites are successfully synthesized using a simple and efficient hydrothermal method. Even-sized anatase TiO 2 nanoparticles are uniformly distributed on GR. The GR/TiO 2 nanocomposites exhibit an extended light absorption range and decreased electron–hole recombination rates. The photocatalytic activity of the as-prepared GR/TiO 2 nanocomposites for bisphenol A (BPA) degradation is investigated under UV (λ = 365 nm) and visible (λ ⩾ 400 nm) light irradiation. The results show that GR/TiO 2 nanocomposites have significantly higher photocatalytic activity than P25 (pure TiO 2 ). The large increase in photocatalytic activity is mostly attributed to effective charge transfer from TiO 2 nanoparticles to GR, which suppresses charge recombination during the photocatalytic process. After five successive cycles, the photodegradation activity of the GR/TiO 2 nanocomposites shows no significant decrease, which indicates that the nanocomposites are stable under UV and visible light. X-ray photoelectron spectroscopy (XPS) is used to investigate the chemical bonds of GR/TiO 2 nanocomposites before and after degradation to determine the degradation intermediate products of BPA under irradiation. A proposed degradation reaction pathway of BPA is also established. This study provides new insights into the fabrication and practical application of high-performance photocatalysts in wastewater treatment

  12. Microwave-assisted synthesis and characterization of poly(acrylic)/SiO2-TiO2 core-shell nanoparticle hybrid thin films

    International Nuclear Information System (INIS)

    Chien, Wen-Chen; Yu, Yang-Yen; Chen, Po-Kan; Yu, Hui-Huan

    2011-01-01

    In this study, poly(acrylic)/SiO 2 -TiO 2 core-shell nanoparticle hybrid thin films were successfully synthesized by microwave-assisted polymerization. The coupling agent 3-(trimethoxysilyl) propyl methacrylate (MSMA) was hydrolyzed with colloidal SiO 2 -TiO 2 core-shell nanoparticles, and then polymerized with two acrylic monomers and initiator to form a precursor solution. The results of this study showed that the spin-coated hybrid films had relatively good surface planarity, high thermal stability, a tunable refractive index (1.525 2 -TiO 2 core-shell nanoparticle hybrid thin films, for potential use in optical applications.

  13. Investigation on the structural and nonlinear optical properties of Pt doped TiO2 nanoparticles

    International Nuclear Information System (INIS)

    Rahulan, K. Mani; Padmanathan, N.; Vinitha, G.; Kanakam, Charles Christopher

    2013-01-01

    Graphical abstract: The open aperture Z-scan traces of Pt doped TiO 2 nanoparticles at different Pt concentrations were carried out at an irradiation wavelength of 532 nm. It was numerically found that, two photon absorption (TPA) type process gives the best fit to the obtained open aperture Z-scan data. The nonlinear transmission was found to be of third order as it fits to a two-photon absorption. The optical limiting performances of nanoparticles were greatly enhanced with increased volume ratio of Pt. Increasing particle size reduced the limiting threshold and enhanced the optical limiting performance. - Highlights: • Pt doped TiO 2 nanoparticles with different concentrations of Pt have been synthesized by sol–gel method. • The average fluorescence lifetime decreases as the volume fraction of Pt dopant increases. • The effects of Pt content on the optical limiting property were investigated by open aperture Z-scan measurements done at 532 nm using 5 ns laser pulses. • The values of the third-order nonlinearities of nanoparticles are interesting from the application point of view which could be used as a potential candidate for the application of nonlinear optical device. - Abstract: Pt doped TiO 2 nanoparticles with different concentrations of Pt were prepared by sol–gel method. X-ray diffraction (XRD) study reveals that the samples have a homogeneous anatase phase tetragonal system and the lattice parameter analysis indicates that Pt ions substitute into the lattice of TiO 2 . The addition of dopant increases the growth of TiO 2 grains, agglomerates them and shifts the absorption band of TiO 2 from ultraviolet to visible region. The incorporation of Pt in TiO 2 is also confirmed by fluorescence quenching and the fluorescence lifetime decreases as the volume fraction of Pt dopant increases. Open aperture Z-scan measurements done at 532 nm using 7 ns laser pulses show nonlinear absorption which arises from an effective two photon absorption process

  14. Promotion of Phenol Photodecomposition over TiO2 Using Au, Pd, and AuPd Nanoparticles

    DEFF Research Database (Denmark)

    Su, Ren; Tiruvalam, Ramchandra; He, Qian

    2012-01-01

    Noble metal nanoparticles (Au, Pd, AuPd alloys) with a narrow size distribution supported on nanocrystalline TiO2 (M/TiO2) have been synthesized via a sol-immobilization route. The effect of metal identity and size on the photocatalytic performance of M/TiO2 has been systematically investigated u...

  15. Epitaxial TiO 2/SnO 2 core-shell heterostructure by atomic layer deposition

    KAUST Repository

    Nie, Anmin; Liu, Jiabin; Li, Qianqian; Cheng, Yingchun; Dong, Cezhou; Zhou, Wu; Wang, Pengfei; Wang, Qingxiao; Yang, Yang; Zhu, Yihan; Zeng, Yuewu; Wang, Hongtao

    2012-01-01

    Taking TiO 2/SnO 2 core-shell nanowires (NWs) as a model system, we systematically investigate the structure and the morphological evolution of this heterostructure synthesized by atomic layer deposition/epitaxy (ALD/ALE). All characterizations

  16. Engineering the surface of rutile TiO2 nanoparticles with quantum pits towards excellent lithium storage

    DEFF Research Database (Denmark)

    Huang, Jinglu; Fang, Fang; Huang, Guoyong

    2016-01-01

    Engineering the surface structure of nanomaterials is of great importance for applications in energy conversion and storage. Herein, unique rutile TiO2 nanoparticles have been successfully synthesized by a facile solution and subsequent thermal annealing method. Each particle surface has been...

  17. Cellulose nanofiber-templated three-dimension TiO 2 hierarchical nanowire network for photoelectrochemical photoanode

    Science.gov (United States)

    Zhaodong Li; Chunhua Yao; Fei Wang; Zhiyong Cai; Xudong Wang

    2014-01-01

    Three dimensional (3D) nanostructures with extremely large porosity possess a great promise for the development of high-performance energy harvesting storage devices. In this paper, we developed a high-density 3D TiO2 fiber-nanorod (NR) heterostructure for photoelectrochemical (PEC) water splitting. The hierarchical structure was synthesized on a...

  18. Optimized nanostructured TiO2 photocatalysts

    Science.gov (United States)

    Topcu, Selda; Jodhani, Gagan; Gouma, Pelagia

    2016-07-01

    Titania is the most widely studied photocatalyst. In it’s mixed-phase configuration (anatase-rutile form) -as manifested in the commercially available P25 Degussa material- titania was previously found to exhibit the best photocatalytic properties reported for the pure system. A great deal of published research by various workers in the field have not fully explained the underlying mechanism for the observed behavior of mixed-phase titania photocatalysts. One of the prevalent hypothesis in the literature that is tested in this work involves the presence of small, active clusters of interwoven anatase and rutile crystallites or “catalytic “hot-spots””. Therefore, non-woven nanofibrous mats of titania were produced and upon calcination the mats consisted of nanostructured fibers with different anatase-rutile ratios. By assessing the photocatalytic and photoelectrochemical properties of these samples the optimized photocatalyst was determined. This consisted of TiO2 nanostructures annealed at 500˚C with an anatase /rutile content of 90/10. Since the performance of this material exceeded that of P25 complete structural characterization was employed to understand the catalytic mechanism involved. It was determined that the dominant factors controlling the photocatalytic behavior of the titania system are the relative particle size of the different phases of titania and the growth of rutile laths on anatase grains which allow for rapid electron transfer between the two phases. This explains how to optimize the response of the pure system.

  19. Electrochemical characteristics of coated steel with poly(N-methyl pyrrole) synthesized in presence of ZnO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Mahmoudian, M.R., E-mail: M_R_mahmoudian@yahoo.com [Department of Chemistry, University of Malaya, Kuala Lumpur 50603 (Malaysia); Department of Chemistry, Masjed-Soleiman Branch, Islamic Azad University, Masjed-Soleiman (Iran, Islamic Republic of); Basirun, W.J.; Alias, Y. [Department of Chemistry, University of Malaya, Kuala Lumpur 50603 (Malaysia); Khorsand Zak, A. [Low Dimensional Materials Research Center, Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2011-10-31

    Poly(N-methyl pyrrole) (PMPy) coating was electrodeposited on steel substrates in mixed electrolytes of dodecyl benzene sulphonic acid with oxalic acid in the absence and the presence of ZnO nanoparticles (NPs). The morphology and compositions were characterized by Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared Spectroscopy and Energy-dispersive X-ray spectroscopy. Electrode/coating/electrolyte system was studied by Electrochemical Impedance Spectroscopy. The comparison between the pore resistance (R{sub po}) of synthesized PMPy in the absence and presence of ZnO NPs indicated that the existence of ZnO increased the R{sub po} of the coating. The FESEM micrographs indicated that the size of micro-spherical grains in the morphology of PMPy is significantly reduced and the surface area of PMPy is increased with the presence of ZnO NPs. The increase of the ability to interact with the ions liberated during the corrosion reaction of steel and the increase of the rate probability for the occurrence of cathodic reduction of oxygen on the PMPy with the increase of the surface area can be considered as reasons for improvement of protective properties of synthesized PMPy in the presence of ZnO NPs.

  20. Few-Layer MoS2 Nanodomains Decorating TiO2 Nanoparticles: A Case Study for the Photodegradation of Carbamazepine

    Directory of Open Access Journals (Sweden)

    Sara Cravanzola

    2018-03-01

    Full Text Available S-doped TiO2 and hybrid MoS2/TiO2 systems have been synthesized, via the sulfidation with H2S of the bare TiO2 and of MoOx supported on TiO2 systems, with the aim of enhancing the photocatalytic properties of TiO2 for the degradation of carbamazepine, an anticonvulsant drug, whose residues and metabolites are usually inefficiently removed in wastewater treatment plants. The focus of this study is to find a relationship between the morphology/structure/surface properties and photoactivity. The full characterization of samples reveals the strong effects of the H2S action on the properties of TiO2, with the formation of defects at the surface, as shown by transmission electron microscopy (TEM and infrared spectroscopy (IR, while also the optical properties are strongly affected by the sulfidation treatment, with changes in the electronic states of TiO2. Meanwhile, the formation of small and thin few-layer MoS2 domains, decorating the TiO2 surface, is evidenced by both high-resolution transmission electron microscopy (HRTEM and UV-Vis/Raman spectroscopies, while Fourier-transform infrared (FTIR spectra give insights into the nature of Ti and Mo surface sites. The most interesting findings of our research are the enhanced photoactivity of the MoS2/TiO2 hybrid photocatalyst toward the carbamazepine mineralization. Surprisingly, the formation of hazardous compounds (i.e., acridine derivatives, usually obtained from carbamazepine, is precluded when treated with MoS2/TiO2 systems.

  1. CdS Nanoparticle-Modified α-Fe2O3/TiO2 Nanorod Array Photoanode for Efficient Photoelectrochemical Water Oxidation.

    Science.gov (United States)

    Yin, Ruiyang; Liu, Mingyang; Tang, Rui; Yin, Longwei

    2017-09-02

    In this work, we demonstrate a facile successive ionic layer adsorption and reaction process accompanied by hydrothermal method to synthesize CdS nanoparticle-modified α-Fe 2 O 3 /TiO 2 nanorod array for efficient photoelectrochemical (PEC) water oxidation. By integrating CdS/α-Fe 2 O 3 /TiO 2 ternary system, light absorption ability of the photoanode can be effectively improved with an obviously broadened optical-response to visible light region, greatly facilitates the separation of photogenerated carriers, giving rise to the enhancement of PEC water oxidation performance. Importantly, for the designed abnormal type-II heterostructure between Fe 2 O 3 /TiO 2 , the conduction band position of Fe 2 O 3 is higher than that of TiO 2 , the photogenerated electrons from Fe 2 O 3 will rapidly recombine with the photogenerated holes from TiO 2 , thus leads to an efficient separation of photogenerated electrons from Fe 2 O 3 /holes from TiO 2 at the Fe 2 O 3 /TiO 2 interface, greatly improving the separation efficiency of photogenerated holes within Fe 2 O 3 and enhances the photogenerated electron injection efficiency in TiO 2 . Working as the photoanodes of PEC water oxidation, CdS/α-Fe 2 O 3 /TiO 2 heterostucture electrode exhibits improved photocurrent density of 0.62 mA cm - 2 at 1.23 V vs. reversible hydrogen electrode (RHE) in alkaline electrolyte, with an obviously negatively shifted onset potential of 80 mV. This work provides promising methods to enhance the PEC water oxidation performance of the TiO 2 -based heterostructure photoanodes.

  2. Tuning metal support interactions enhances the activity and durability of TiO2-supported Pt nanocatalysts

    International Nuclear Information System (INIS)

    Hsieh, Bing-Jen; Tsai, Meng-Che; Pan, Chun-Jern; Su, Wei-Nien; Rick, John; Chou, Hung-Lung; Lee, Jyh-Fu; Hwang, Bing-Joe

    2017-01-01

    Highlights: • The coverage of TiO x on Pt can be modified by thermal and fluoric acid treatments. • Strong metal support interaction (SMSI) can be testified by electrochemical method. • For the first time, the SMSI effect is observed at 200 °C with supporting TEM images. • Increased activity and stability are attributed to stronger SMSI. • This tunable approach is valid for other oxide supported catalysts, e.g. Pt/Nb-TiO 2 . - Abstract: A facile approach to enhance catalytic activity and durability of TiO 2 -supported Pt nanocatalysts by tuning strong metal support interaction (SMSI) is investigated in this work. No need for a high temperature treatment, the strong metal-support interaction (SMSI) in TiO 2 -supported Pt can be induced at 200° C by H 2 reduction. Moreover, electrochemical methods (methanol oxidation reaction and cyclic voltammetry) are first reported ever to be effective characterization tools for the coverage state caused by SMSI. In addition, the SMSI has also been confirmed by X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, and Transmission Electron Microscopy. It is found that the encapsulation of TiO 2-x species on the surface Pt clusters was induced and modified by thermal reduction and fluoric acid treatment. The catalytic activity and durability of the TiO 2 -supported Pt nanocatalysts are strongly dependent of the state of SMSI. The proposed SMSI-tunable approach to enhance the ORR activity and stability is also proved applicable to Pt/Ti 0.9 Nb 0.1 O 2 nanocatalysts. We believe that the reported approach paves the way for manipulating the activity and stability of other TiO 2 -supported metal nanocatalysts. Furthermore, the suggested electrochemical methods offer facile and effective ways to verify the presence of coverage state before combining with other physical analysis.

  3. Enhancement in dye-sensitized solar cells based on MgO-coated TiO2 electrodes by reactive DC magnetron sputtering

    International Nuclear Information System (INIS)

    Wu Sujuan; Han Hongwei; Tai Qidong; Zhang Jing; Xu Sheng; Zhou Conghua; Yang Ying; Hu Hao; Chen Bolei; Sebo, Bobby; Zhao Xingzhong

    2008-01-01

    A surface modification method was carried out by reactive DC magnetron sputtering to fabricate TiO 2 electrodes coated with insulating MgO for dye-sensitized solar cells. The MgO-coated TiO 2 electrode had been characterized by x-ray photoelectron spectroscopy (XPS), energy-dispersive x-ray spectroscopy (EDX), scanning electron microscopy (SEM), UV-vis spectrophotometer, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The study results revealed that the TiO 2 modification increases dye adsorption, decreases trap states and suppresses interfacial recombination. The effects of sputtering MgO for different times on the performance of DSSCs were investigated. It indicated that sputtering MgO for 3 min on TiO 2 increases all cell parameters, resulting in increasing efficiency from 6.45% to 7.57%

  4. Graphene-embedded 3D TiO2 inverse opal electrodes for highly efficient dye-sensitized solar cells: morphological characteristics and photocurrent enhancement.

    Science.gov (United States)

    Kim, Hye-Na; Yoo, Haemin; Moon, Jun Hyuk

    2013-05-21

    We demonstrated the preparation of graphene-embedded 3D inverse opal electrodes for use in DSSCs. The graphene was incorporated locally into the top layers of the inverse opal structures and was embedded into the TiO2 matrix via post-treatment of the TiO2 precursors. DSSCs comprising the bare and 1-5 wt% graphene-incorporated TiO2 inverse opal electrodes were compared. We observed that the local arrangement of graphene sheets effectively enhanced electron transport without significantly reducing light harvesting by the dye molecules. A high efficiency of 7.5% was achieved in DSSCs prepared with the 3 wt% graphene-incorporated TiO2 inverse opal electrodes, constituting a 50% increase over the efficiencies of DSSCs prepared without graphene. The increase in efficiency was mainly attributed to an increase in J(SC), as determined by the photovoltaic parameters and the electrochemical impedance spectroscopy analysis.

  5. Comparative study of the anchorage and the catalytic properties of nanoporous TiO2 films modified with ruthenium (II) and rhenium (I) carbonyl complexes

    Science.gov (United States)

    Oyarzún, Diego P.; Chardon-Noblat, Sylvie; Linarez Pérez, Omar E.; López Teijelo, Manuel; Zúñiga, César; Zarate, Ximena; Shott, Eduardo; Carreño, Alexander; Arratia-Perez, Ramiro

    2018-02-01

    In this article we study the anchoring of cis-[Ru(bpyC4pyr)(CO)2(CH3CN)2]2+, cis-[Ru(bpy)2(CO)2]2+ and cis-[Ru(bpyac)(CO)2Cl2], onto nanoporous TiO2 employing electropolymerization, electrostatic interaction and chemical bonding. Also, the [Re(bpyac)(CO)3Cl] rhenium(I) complex for chemical anchorage was analyzed. The characterization of TiO2/Ru(II) and TiO2/Re(I) nanocomposite films was performed by field emission scanning electron microscopy (FESEM), electron dispersive X-ray spectroscopy (EDS) and Raman spectroscopy. In addition, for the more stable nanocomposites obtained, the catalytic properties (solar energy conversion and CO2 reduction) were evaluated. The efficiency improvement in redox process derived from the (photo)electrochemical evidence indicates that modified nanoporous TiO2 structures enhance the rate of charge transfer reactions.

  6. Synthesis and characterization of Fe3+ doped TiO2 nanoparticles and films and their performance for photocurrent response under UV illumination

    International Nuclear Information System (INIS)

    Elghniji, Kais; Atyaoui, Atef; Livraghi, Stefano; Bousselmi, Latifa; Giamello, Elio; Ksibi, Mohamed

    2012-01-01

    Graphical abstract: Schematic diagram illustrating the charge transfer from excited TiO 2 to the different states of Fe 3+ ions; C B and V B refer to the energy levels of the conduction and valence bands of TiO 2 , respectively. Highlights: ► In this study we examine the Iron as catalyst precursor to synthesize the Fe 3+ doped TiO 2 nanoparticles. ► The Fe 3+ doped TiO 2 catalysts show the presence of a mixed phase of anatase. ► The iron is completely absent in the XRD pattern of the doped iron TiO 2 powder. ► The analysis of EPR result further confirms that Fe 3+ ion are successfully doped in the TiO 2 lattice by substituting Ti 4+ . ► Fe 3+ doping can efficiently separate the photo-generated electrons and holes. - Abstract: Undoped TiO 2 and Fe 3+ doped (0.1, 0.3, 0.6 and 1 wt.%) TiO 2 nanoparticles have been synthesized by the acid-catalyzed sol–gel method. Iron cations are introduced in the initial solution, before gelification, what promotes their lattice localization. The Fe 3+ doped TiO 2 films have been fabricated using a dip-coating technique. The effect of iron content on the crystalline structure, phase transformation and grain growth were determined by X-ray diffraction (XRD), Raman spectroscopy, UV–visible diffused reflectance spectroscopy (DRS) and Electron paramagnetic resonance (EPR) spectroscopy. It has demonstrated that all catalysts are composed of mixed-phase crystals of anatase and brookite with anatase as dominant phase. The crystallinity of the brookite and anatase phases decreased with increasing the iron content. The analysis of EPR result further confirms that Fe 3+ ion are successfully doped in the TiO 2 lattice by substituting Ti 4+ . It was demonstrated that Fe 3+ ion in the TiO 2 films plays a role as the intermediate for the efficient separation of photogenerated hole–electron pairs and increases the photocurrent response of the film under UV light irradiation. The maximum photocurrent is obtained on the Fe 3+ doped Ti

  7. Thermal analysis and temperature dependent dielectric responses of Co doped anatase TiO2 nanoparticles

    International Nuclear Information System (INIS)

    Alamgir; Khan, Wasi; Ahammed, Nashiruddin; Naqvi, A. H.; Ahmad, Shabbir

    2015-01-01

    Nanoparticles (NPs) of pure and 5 mol % cobalt doped TiO 2 synthesized through acid modified sol-gel method were characterized to understand their thermal, structural, morphological, and temperature dependent dielectric properties. Thermogravimetric analysis (TGA) has been used for thermal studies and indicates the weight loss in two steps due to the removal of residual organics. X-ray diffraction study was employed to confirm the formation of single anatase phase with tetragonal symmetry for both pure and 5 mol % Co doped TiO 2 NPs. The average crystallite size of both samples was calculated from the Scherrer’s formula and was found in the range from 9-11 nm. TEM micrographs of these NPs reflect their shape and distribution. The dielectric constant (ε′), dielectric loss (tanδ) and ac conductivity (σ ac ) were also studied as a function of temperature at different frequencies. Electrical responses of the synthesized NPs have been analyzed carefully in the framework of relevant models. It is also noticed that the dielectric constant (ε′) of the samples found to decrease with increasing frequency but increases with increasing temperature up to a particular value and then sharply decreases. Temperature variation of dielectric constant exhibits step like escalation and shows relaxation behavior. Study of dielectric properties shows dominant dependence on the grain size as well as Co ion incorporation in TiO 2

  8. Surface-Enhanced Infrared Absorption of o-Nitroaniline on Nickel Nanoparticles Synthesized by Electrochemical Deposition

    Directory of Open Access Journals (Sweden)

    Yufang Niu

    2014-01-01

    Full Text Available Nickel nanoparticles were electrochemically deposited on indium-tin oxide (ITO coated glass plate in a modified Watt’s electrolyte. The surface-enhanced infrared absorption (SEIRA effect of the nanoparticles was evaluated by attenuated total reflection spectroscopy (ATR-FTIR using o-nitroaniline as a probe molecule. Electrodeposition parameters such as deposition time, pH value, and the type of surfactants were investigated. The morphology and the microstructure of the deposits were characterized by the field emission scanning electron microscope (FESEM and the atomic force microscope (AFM, respectively. The results indicate that the optimum parameters were potential of 1.3 V, time of 30 s, and pH of 8.92 in the solution of 0.3756 mol/L diethanolamine, 0.1 mol/L nickel sulfate, 0.01 mol/L nickel chloride, and 0.05 mol/L boric acid. The FESEM observation shows that the morphology of nickel nanoparticles with best enhancement effect is spherical and narrowly distributed particles with the average size of 50 nm. SEIRA enhancement factor is about 68.

  9. Tuning the relative concentration ratio of bulk defects to surface defects in TiO2 nanocrystals leads to high photocatalytic efficiency.

    Science.gov (United States)

    Kong, Ming; Li, Yuanzhi; Chen, Xiong; Tian, Tingting; Fang, Pengfei; Zheng, Feng; Zhao, Xiujian

    2011-10-19

    TiO(2) nanocrystals with tunable bulk/surface defects were synthesized and characterized with TEM, XRD, BET, positron annihilation, and photocurrent measurements. The effect of defects on photocatalytic activity was studied. It was found for the first time that decreasing the relative concentration ratio of bulk defects to surface defects in TiO(2) nanocrystals could significantly improve the separation efficiency of photogenerated electrons and holes, thus significantly enhancing the photocatalytic efficiency.

  10. Synthesis, Structural and Optical Properties of Co Doped TiO2 Nanocrystals by Sol-Gel Method

    OpenAIRE

    Sridevi , D.V ,; Ramesh , V; Sakthivel , T; Geetha , K ,; Ratchagar , V ,; Jagannathan , K ,; Rajarajan , K ,; Ramachadran , K ,

    2017-01-01

    International audience; A TiO2 nanoparticle doped with cobalt was synthesized by sol-gel technique employed at room temperature with appropriate reactants. In the present case, we used titanium tetra isoprotoxide (TTIP) and 2–propanol as a common starting material and the obtained products were calcined at 450˚C450˚450˚C. From the Powder XRD data the particle size was calculated by Scherrer method. The FE-SEM analysis shows the morphology of cobalt doped TiO2 nanoparticles. The various functi...

  11. A visible-light-driven composite photocatalyst of TiO2 nanotube arrays and graphene quantum dots

    Directory of Open Access Journals (Sweden)

    Donald K. L. Chan

    2014-05-01

    Full Text Available TiO2 nanotube arrays are well-known efficient UV-driven photocatalysts. The incorporation of graphene quantum dots could extend the photo-response of the nanotubes to the visible-light range. Graphene quantum dot-sensitized TiO2 nanotube arrays were synthesized by covalently coupling these two materials. The product was characterized by Fourier-transform infrared spectrometry (FTIR, scanning electron microscopy (SEM, transmission electron microscopy (TEM, X-ray diffraction (XRD, thermogravimetric analysis (TGA and UV–vis absorption spectroscopy. The product exhibited high photocatalytic performance in the photodegradation of methylene blue and enhanced photocurrent under visible light irradiation.

  12. MoS2 embedded TiO2 nanoparticles for concurrent role of adsorption and photocatalysis

    Science.gov (United States)

    Pal, Arnab; Jana, Tushar K.; Chatterjee, Kuntal

    2018-04-01

    In this work, MoS2 embedded TiO2 nanoparticles, synthesized through hydrothermal process, was successfully employed to remove organic pollutant dye like methylene blue(MB) through adsorption and as well as through photocatalysis under visible light irradiation. The system was characterized by structural and morphological study. The adsorption and photocatalytic study of MB were evaluated with different concentrations of dye in aqueous solution. This work brings the MoS2-TiO2 nanostructure as excellent adsorbent as well as efficient photocatalyst materials which can be used for organic dye removal towards waste-water treatment.

  13. Facile Synthesis and Tensile Behavior of TiO2 One-Dimensional Nanostructures

    Directory of Open Access Journals (Sweden)

    Li Shu-you

    2009-01-01

    Full Text Available Abstract High-yield synthesis of TiO2 one-dimensional (1D nanostructures was realized by a simple annealing of Ni-coated Ti grids in an argon atmosphere at 950 °C and 760 torr. The as-synthesized 1D nanostructures were single crystalline rutile TiO2 with the preferred growth direction close to [210]. The growth of these nanostructures was enhanced by using catalytic materials, higher reaction temperature, and longer reaction time. Nanoscale tensile testing performed on individual 1D nanostructures showed that the nanostructures appeared to fracture in a brittle manner. The measured Young’s modulus and fracture strength are ~56.3 and 1.4 GPa, respectively.

  14. Room-temperature ferromagnetism in Co and Nb co-doped TiO2 nanoparticles

    International Nuclear Information System (INIS)

    Hachisu, M.; Mori, K.; Hyodo, K.; Morimoto, S.; Yamazaki, T.; Ichiyanagi, Y.

    2015-01-01

    Co- and Nb-doped TiO 2 nanoparticles encapsulated with amorphous SiO 2 were synthesized by our novel preparation method. An anatase TiO 2 single-phase structure was confirmed using X-ray diffraction. The particle size could be controlled to be about 5 nm. The composition of these nanoparticles was investigated by X-ray fluorescence analysis. X-ray absorption near-edge structure spectra showed that the Ti 4+ and Co 2+ states were dominant in our prepared samples. A reduction in the coordination number was also confirmed. The dependence of the electrical conductivity on the frequency was measured by an LCR meter, and the carrier concentration was determined. The magnetization curves for the nanoparticles indicated ferromagnetic behavior at room temperature. We concluded that the ferromagnetism originated in oxygen vacancies around the transition metal ions

  15. Synthesis and Characterization of Nanostructure Tio2/Anthraquenone (AQ Prepared by Sol-Gel Method

    Directory of Open Access Journals (Sweden)

    Fadhela M. Hussein

    2017-11-01

    Full Text Available sol–gel technique conducted to synthesize nano titanium dioxide with anthraquenone (AQ relatively in acidic pH. Nanoparticles were characterized using techniques like, Scanning Electrion Microscope (SEM, Atomic Force Microscope (AFM, UV-Visible Spectrioscopy, X-ray diffraction (XRD, Fourier transform infrared (FT-IR, SEM picture display that the TiO2/AQ is spherical in style, the band gap of TiO2/AQ nanoparticle is (3.05eV, BET and BJH analysis provides Pore volume and specific Surface area and the kinetic studie Suggest that the reaction is pseudo first order and the rate of reaction was reduce with rising initial concentration for p-Nitrotolune.

  16. A Designed TiO2 /Carbon Nanocomposite as a High-Efficiency Lithium-Ion Battery Anode and Photocatalyst.

    Science.gov (United States)

    Peng, Liang; Zhang, Huijuan; Bai, Yuanjuan; Feng, Yangyang; Wang, Yu

    2015-10-12

    Herein, a peapod-like TiO2 /carbon nanocomposite has successfully been synthesized by a rational method for the first time. The novel nanostructure exhibits a distinct feature of TiO2 nanoparticles encapsulated inside and the carbon fiber coating outside. In the synthetic process, H2 Ti3 O7 nanotubes serve as precursors and templates, and glucose molecules act as the green carbon source. With the alliciency of hydrogen bonding between H2 Ti3 O7 and glucose, a thin polymer layer is hydrothermally assembled and subsequently converted into carbon fibers through calcinations under an inert atmosphere. Meanwhile, the precursors of H2 Ti3 O7 nanotubes are transformed into the TiO2 nanoparticles encapsulated in carbon fibers. The achieved unique nanocomposites can be used as excellent anode materials in lithium-ion batteries (LIBs) and photocatalytic reagents in the degradation of rhodamine B. Due to the synergistic effect derived from TiO2 nanoparticles and carbon fibers, the obtained peapod-like TiO2 /carbon cannot only deliver a high specific capacity of 160 mAh g(-1) over 500 cycles in LIBs, but also perform a much faster photodegradation rate than bare TiO2 and P25. Furthermore, owing to the low cost, environmental friendliness as well as abundant source, this novel TiO2 /carbon nanocomposite will have a great potential to be extended to other application fields, such as specific catalysis, gas sensing, and photovoltaics. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Hierarchical Honeycomb Br-, N-Codoped TiO2 with Enhanced Visible-Light Photocatalytic H2 Production.

    Science.gov (United States)

    Zhang, Chao; Zhou, Yuming; Bao, Jiehua; Sheng, Xiaoli; Fang, Jiasheng; Zhao, Shuo; Zhang, Yiwei; Chen, Wenxia

    2018-06-06

    The halogen elements modification strategy of TiO 2 encounters a bottleneck in visible-light H 2 production. Herein, we have for the first time reported a hierarchical honeycomb Br-, N-codoped anatase TiO 2 catalyst (HM-Br,N/TiO 2 ) with enhanced visible-light photocatalytic H 2 production. During the synthesizing process, large amounts of meso-macroporous channels and TiO 2 nanosheets were fabricated in massive TiO 2 automatically, constructing the hierarchical honeycomb structure with large specific surface area (464 m 2 g -1 ). cetyl trimethylammonium bromide and melamine played a key role in constructing the meso-macroporous channels. Additionally, HM-Br,N/TiO 2 showed a high visible-light H 2 production rate of 2247 μmol h -1 g -1 , which is far more higher than single Br- or N-doped TiO 2 (0 or 63 μmol h -1 g -1 , respectively), thereby demonstrating the excellent synergistic effects of Br and N elements in H 2 evolution. In HM-Br,N/TiO 2 catalytic system, the codoped Br-N atoms could reduce the band gap of TiO 2 to 2.88 eV and the holes on acceptor levels (N acceptor) can passivate the electrons on donor levels (Br donor), thereby preventing charge carriers recombination significantly. Furthermore, the proposed HM-Br,N/TiO 2 fabrication strategy had a wide range of choices for N source (e.g., melamine, urea, and dicyandiamide) and it can be applied to other TiO 2 materials (e.g., P25) as well, thereby implying its great potential application in visible-light H 2 production. Finally, on the basis of experimental results, a possible photocatalytic H 2 production mechanism for HM-Br,N/TiO 2 was proposed.

  18. Synthesis of Cr3+-doped TiO2 nanoparticles: characterization and evaluation of their visible photocatalytic performance and stability.

    Science.gov (United States)

    Mendiola-Alvarez, Sandra Yadira; Guzmán-Mar, Jorge Luis; Turnes-Palomino, Gemma; Maya-Alejandro, Fernando; Caballero-Quintero, Adolfo; Hernández-Ramírez, Aracely; Hinojosa-Reyes, Laura

    2017-09-28

    Cr 3+ -doped TiO 2 nanoparticles (Ti-Cr) were synthesized by microwave-assisted sol-gel method. The Ti-Cr catalyst was characterized by X-ray diffraction, ultraviolet-visible diffuse reflectance spectroscopy, N 2 adsorption-desorption analysis, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, photoluminescence spectroscopy, X-ray photoelectron spectroscopy (XPS) and zetametry. The anatase mesoporous Ti-Cr material exhibited a specific surface area of 54.5 m 2 /g. XPS analysis confirmed the proper substitution of Ti 4+ cations by Cr 3+ cations in the TiO 2 matrix. The particle size was of average size of 17 nm for the undoped TiO 2 but only 9.5 nm for Ti-Cr. The Cr atoms promoted the formation of hydroxyl radicals and modified the surface adsorptive properties of TiO 2 due to the increase in surface acidity of the material. The photocatalytic evaluation demonstrated that the Ti-Cr catalyst completely degraded (4-chloro-2-methylphenoxy) acetic acid under visible light irradiation, while undoped TiO 2 and P25 allowed 45.7% and 31.1%, respectively. The rate of degradation remained 52% after three cycles of catalyst reuse. The higher visible light photocatalytic activity of Ti-Cr was attributed to the beneficial effect of Cr 3+ ions on the TiO 2 surface creating defects within the TiO 2 crystal lattice, which can act as charge-trapping sites, reducing the electron-hole recombination process.

  19. A new approach of tailoring wetting properties of TiO2 nanotubular surfaces

    KAUST Repository

    Isimjan, Tayirjan T.

    2012-11-01

    TiO2 nanotube layers were grown on a Ti surface by electrochemical anodization. As prepared, these layers showed a superhydrophilic wetting behavior. Modified with 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane (PTES), the layers showed a superhydrophobic behavior. We demonstrate how to change the surface characteristics of the TiO2 nanotube layers in order to achieve any desirable degree of hydrophobicity between 100° to 170°. The treated superhydrophobic TiO2 nanotube layers have an advanced contact angle exceeding 165°, a receding angle more than 155°and a slide angle less than 5°. It is found that the surface morphology of the film which depends on anodization time among other variables, has a great influence on the superhydrophobic properties of the surface after PTES treatment. The hydrodynamic properties of the surface are discussed in terms of both Cassie and Wenzel mechanisms. The layers are characterized with dynamic contact angle measurements, SEM, and XPS analyses. © 2012 American Scientific Publishers.

  20. Growth and characterization of hydroxyapatite nanorice on TiO2 nanofibers

    KAUST Repository

    Chetibi, Loubna

    2014-04-01

    Hydroxyapatite (HA) coating with nanoparticles like nanorice is fabricated on chemically pretreated titanium (Ti) surface, through an electrochemical deposition approach, for biomaterial applications. The Ti surface was chemically patterned with anatase TiO2 nanofibers. These nanofibers were prepared by in situ oxidation of Ti foils in a concentrated solution of H 2O2 and NaOH, followed by proton exchange and calcinations. Afterward, TiO2 nanofibers on Ti substrate were coated with HA nanoparticles like nanorice. The obtained samples were annealed at high temperature to produce inter diffusion between TiO2 and HA layers. The resultant layers were characterized by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction (XRD), Infrared Spectroscopy (FTIR), corrosion tests in SBF solution, and Electron Probe Micro Analysis (EPMA). It was found that only Ti from the titanium substrate diffuses into the HA coating and a good corrosion resistance in simulated body fluid was obtained. © 2014 Elsevier B.V. All rights reserved.

  1. Performance and electron transport properties of TiO2 nanocomposite dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Wu, J-J; Chen, G-R; Lu, C-C; Wu, W-T; Chen, J-S

    2008-01-01

    TiO 2 nanowire (NW)/nanoparticle (NP) composite films have been fabricated by hybridizing various ratios of hydrothermal anatase NWs and TiO 2 NPs for use in dye-sensitized solar cells (DSSCs). Scanning electron microscopy (SEM) images reveal that uniform NW/NP composite films were formed on fluorine-doped tin oxide (FTO) substrates by the dip-coating method. The NWs are randomly but neither vertically nor horizontally oriented within the composite film. The TiO 2 NP DSSC possesses superior performance to those of the NW/NP composite and the pure NW cells, and the efficiency of the NW/NP composite DSSC increases on increasing the NP/NW ratio in the composite anode. All types of DSSC possess the same dependence of performance on the anode thickness that the efficiency increases with the anode thickness to a maximum value, then it decreases when the anode is thickened further. Electrochemical impedance spectroscopy analyses reveal that the NP DSSCs possess larger effective electron diffusion coefficients (D eff ) in the photoanodes and smaller diffusion resistances of I 3 - in electrolytes compared to those in the NW/NP and the NW DSSCs. D eff decreases when NWs are added into the photoanode. These results suggest that the vertical feature of the NWs within the anodes is crucial for achieving a high electron transport rate in the anode

  2. Pseudocapacitance of amorphous TiO2@nitrogen doped graphene composite for high rate lithium storage

    International Nuclear Information System (INIS)

    Li, Sheng; Xue, Pan; Lai, Chao; Qiu, Jingxia; Ling, Min; Zhang, Shanqing

    2015-01-01

    The high rate applications such as electric vehicles of the traditional lithium ion batteries (LIBs) are commonly limited by their insufficient electron conductivity and slow mass transport of lithium ions in bulk electrode materials. In order to address these issues, in this work, a simple and up-scalable wet-mechanochemical (wet-ball milling) route has been developed for fabrication of amorphous porous TiO 2 @nitrogen doped graphene (TiO 2 @N-G) nanocomposites. The amorphous phase, unique porous structure of TiO 2 and the surface defects from nitrogen doping to graphene planes have incurred surface controlled reactions, contributing pseudocapacitance to the total capacity of the battery. It plays a dominant role in producing outstanding high rate electrochemical performance, e.g., 182.7 mAh/g (at 3.36 A/g) after 100 cycles. The design and synthesis of electrode materials with enhanced conductivity and surface pseudocapacitance can be a promising way for high rate LIBs.

  3. Application of electrochemically synthesized ferrate(VI in the purification of wastewater from coal separation plant

    Directory of Open Access Journals (Sweden)

    Čekerevac Milan I.

    2010-01-01

    Full Text Available The oxidative and coagulation efficiency of Na2FeO4 solution, electrochemically generated by trans-passive anodic oxidation of electrical steel in 10M NaOH solution, is confirmed in the process of purification of heavily contaminated wastewater from coal separation plant. The decontamination efficiency is evaluated comparing the values of selected contamination parameters obtained by chemical and biochemical analysis of plant effluent water and water obtained after decontamination with ferrate(VI solution in relatively simple laboratory procedure. The sample of 450 ml of wastewater is treated in laboratory conditions with 100cm3 solution of 1 mg dm-3 Na2FeO4 in 10M NaOH. The chemical analysis of effluent water after treatment have shown almost 3 times lower permanganate index, about 3 times lower iron content, 1.45 times lower As3+ content, 7.35 times lower ammonia content. Turbidity and chemical oxygen demand (COD is reduced for more than 5.77and 13.4 times, respectively. The suspended and colloid matter is eliminated from effluent water after treatment with ferrate(VI solution. Also, biochemical exploration has confirmed high efficiency of ferrate(VI in organics and microbial elimination showing 7.1 times lower 5-days bio-chemical oxygen demand (BOD5, and total elimination of aerobic and anaerobic bacteria from effluent water. According to standards on quality of industrial wastewater effluents, it may be concluded that ferrate(VI treatment of wastewater almost completely eliminates excess of dangerous chemicals and pathogen bacteria, with the exemption of arsenic. Thus, ferrate(VI shows capable performance in treatment of coal separation plant wastewater.

  4. Hydrothermal synthesis of TiO2-ZnO-graphene nanocomposite towards photocatalytic and photovoltaic applications

    International Nuclear Information System (INIS)

    Gayathri, S.; Jayabal, P.; Ramakrishnan, V.

    2015-01-01

    Titanium dioxide (TiO 2 ) - Zinc oxide (ZnO) - Graphene (G) nanocomposite was successfully synthesized through facile hydrothermal method. The X-ray diffraction (XRD) pattern and the micro-Raman spectroscopic technique revealed the formation of TiO 2 -ZnO-Graphene (TZG) nanocomposite. The ZnO and TiO 2 nanoparticles decorated graphene sheets were clearly noticeable in the Field Emission Scanning Electron Micrograph (FE-SEM). The UV-Visible absorption spectra clearly indicated that the formation of TZG nanocomposite enriched the absorption in the visible region. Hence, the prepared nanocomposite can be used as photocatalyst to remove organic dyes from water and as photoanode in the fabrication of dye sensitized solar cells (DSSCs)

  5. Synthesis of Nanocrystalline SnO2 Modified TiO2:a Material for Carbon Monoxide Gas Sensor

    Directory of Open Access Journals (Sweden)

    A. B. BODADE

    2008-11-01

    Full Text Available Nanocrystalline SnO2 doped TiO2 having average crystallite size of 45-50 nm were synthesized by the sol-gel method and studied for gas sensing behavior to reducing gases like CO, liquefied petroleum gas (LPG, NH3 and H2. The material characterization was done by using X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FT-IR and scanning electron microscope (SEM. The sensitivity measurements were carried out as a function of different operating temperature in SnO2 doped TiO2. The 15 wt.% SnO2 doped TiO2 based CO sensor shows better sensitivity at an operating temperature 240°C Incorporation of 0.5 wt% Pd improved the sensitivity, selectivity, response time and reduced the operating temperature from 240°C to 200°C for CO sensor.

  6. Hydrothermal synthesis of TiO2-ZnO-graphene nanocomposite towards photocatalytic and photovoltaic applications

    Science.gov (United States)

    Gayathri, S.; Jayabal, P.; Ramakrishnan, V.

    2015-06-01

    Titanium dioxide (TiO2) - Zinc oxide (ZnO) - Graphene (G) nanocomposite was successfully synthesized through facile hydrothermal method. The X-ray diffraction (XRD) pattern and the micro-Raman spectroscopic technique revealed the formation of TiO2-ZnO-Graphene (TZG) nanocomposite. The ZnO and TiO2 nanoparticles decorated graphene sheets were clearly noticeable in the Field Emission Scanning Electron Micrograph (FE-SEM). The UV-Visible absorption spectra clearly indicated that the formation of TZG nanocomposite enriched the absorption in the visible region. Hence, the prepared nanocomposite can be used as photocatalyst to remove organic dyes from water and as photoanode in the fabrication of dye sensitized solar cells (DSSCs).

  7. The directed preparation of TiO2 nanotubes film on FTO substrate via hydrothermal method for gas sensing application

    Directory of Open Access Journals (Sweden)

    Pham Van Viet

    2016-04-01

    Full Text Available In this research, we directly synthesized TiO2 nanotubes film on Fluorine doped Tin oxide (FTO substrate via hydrothermal method from commercial TiO2 in NaOH solution at 135 ℃ for 24 hours. The samples were characterized by X-ray diffraction (XRD pattern, field emission scanning electron microscopy (FESEM and transmitting electron microscopy (TEM. The average diameter of TiO2 nanotubes (TNTs is about 10–12 nm and their length is about a few hundred nanometers. The sensitivity ability of TNTs increases as the gas concentration increases and developing to the highest sensitivity of TNTs is 2.4 at 700 ppm of the ethanol concentration. The same as the gas concentration, the sensitivity of TNTs increases when the temperature increases. Besides, the sensitivity of samples at 250 ℃ is doubled compared to samples determined at 100 ℃.

  8. Low-Temperature Synthesis of Anatase TiO2 Nanoparticles with Tunable Surface Charges for Enhancing Photocatalytic Activity

    Science.gov (United States)

    Li, Ye; Qin, Zhenping; Guo, Hongxia; Yang, Hanxiao; Zhang, Guojun; Ji, Shulan; Zeng, Tingying

    2014-01-01

    In this work, the positively or negatively charged anatase TiO2 nanoparticles were synthesized via a low temperature precipitation-peptization process (LTPPP) in the presence of poly(ethyleneimine) (PEI) and poly(sodium4- styrenesulfonate) (PSS). X-ray diffraction (XRD) pattern and high-resolution transmission electron microscope (HRTEM) confirmed the anatase crystalline phase. The charges of the prepared TiO2, PEI-TiO2 and PSS-TiO2 nanoparticles were investigated by zeta potentials. The results showed that the zeta potentials of PEI-TiO2 nanoparticles can be tuned from +39.47 mV to +95.46 mV, and that of PSS-TiO2 nanoparticles can be adjusted from −56.63 mV to −119.32 mV. In comparison with TiO2, PSS-TiO2 exhibited dramatic adsorption and degradation of dye molecules, while the PEI modified TiO2 nanoparticles showed lower photocatalytic activity. The photocatalytic performances of these charged nanoparticles were elucidated by the results of UV-vis diffuse reflectance spectra (DRS) and the photoluminescence (PL) spectra, which indicated that the PSS-TiO2 nanoparticles showed a lower recombination rate of electron-hole pairs than TiO2 and PEI-TiO2. PMID:25506839

  9. Highly piezoelectric BaTiO3 nanorod bundle arrays using epitaxially grown TiO2 nanomaterials

    Science.gov (United States)

    Jang, Seon-Min; Yang, Su Chul

    2018-06-01

    Low-dimensional piezoelectric nanostructures such as nanoparticles, nanotubes, nanowires, nanoribbons and nanosheets have been developed for potential applications as energy harvesters, tunable sensors, functional transducers and low-power actuators. In this study, lead-free BaTiO 3 nanorod bundle arrays (NBA) with highly piezoelectric properties were successfully synthesized on fluorine-doped tin oxide (FTO) substrate via a two-step process consisting of TiO2 epitaxial growth and BaTiO3 conversion. Through the TiO2 epitaxial growth on FTO substrate, (001) oriented TiO2 nanostructures formed vertically-aligned NBA with a bundle diameter of 80 nm and an aspect ratio of six. In particular, chemical etching of the TiO2 NBA was conducted to enlarge the surface area for effective Ba2+ ion diffusion during the perovskite conversion process from TiO2 to BaTiO3. The final structure of perovskite BaTiO3 NBA was found to exhibit a feasible piezoelectric response of 3.56 nm with a clear phase change of 180° from the single BaTiO3 bundle, by point piezoelectric forced microscopy (PFM) analysis. Consequently, highly piezoelectric NBA could be a promising nanostructure for various nanoscale electronic devices.

  10. Au Nanoclusters Sensitized Black TiO2-x Nanotubes for Enhanced Photodynamic Therapy Driven by Near-Infrared Light.

    Science.gov (United States)

    Yang, Dan; Gulzar, Arif; Yang, Guixin; Gai, Shili; He, Fei; Dai, Yunlu; Zhong, Chongna; Yang, Piaoping

    2017-12-01

    The low reactive oxygen species production capability and the shallow tissue penetration of excited light (UV) are still two barriers in photodynamic therapy (PDT). Here, Au cluster anchored black anatase TiO 2- x nanotubes (abbreviated as Au 25 /B-TiO 2- x NTs) are synthesized by gaseous reduction of anatase TiO 2 NTs and subsequent deposition of noble metal. The Au 25 /B-TiO 2- x NTs with thickness of about 2 nm exhibit excellent PDT performance. The reduction process increased the density of Ti 3+ on the surface of TiO 2 , which effectively depresses the recombination of electron and hole. Furthermore, after modification of Au 25 nanoclusters, the PDT efficiency is further enhanced owing to the changed electrical distribution in the composite, which forms a shallow potential well on the metal-TiO 2 interface to further hamper the recombination of electron and hole. Especially, the reduction of anatase TiO 2 can expend the light response range (UV) of TiO 2 to the visible and even near infrared (NIR) light region with high tissue penetration depth. When excited by NIR light, the nanoplatform shows markedly improved therapeutic efficacy attributed to the photocatalytic synergistic effect, and promotes separation or restrained recombination of electron and hole, which is verified by experimental results in vitro and in vivo. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Linear and nonlinear optical studies of bare and copper doped TiO2 nanoparticles via sol gel technique

    Science.gov (United States)

    Rajamannan, B.; Mugundan, S.; Viruthagiri, G.; Praveen, P.; Shanmugam, N.

    2014-01-01

    In general, the nanoparticles of TiO2 may exist in the phases of anatase, rutile and brookite. In the present work, we used titanium terta iso propoxide and 2-propanol as a common starting material to prepare the precursors of bare and copper doped nanosized TiO2. Then the synthesized products were calcinated at 500 °C and after calcination the pure TiO2 nanoparticles in anatase phase were harvested. The crystallite sizes of bare and copper doped TiO2 nanoparticles were calculated from X-ray diffraction analysis. The existence of functional groups of the samples was identified by Fourier transform infrared spectroscopy. The optical properties of bare and doped samples were carried out using UV-DRS and photoluminescence measurements. The surface morphology and the element constitution of the copper doped TiO2 nanoparticles were studied by scanning electron microscope fitted with energy dispersive X-ray spectrometer arrangement. The nonlinear optical properties of the products were confirmed by Kurtz second harmonic generation (SHG) test and the output power generated by the nanoparticle was compared with that of potassium di hydrogen phosphate (KDP).

  12. Highly piezoelectric BaTiO3 nanorod bundle arrays using epitaxially grown TiO2 nanomaterials.

    Science.gov (United States)

    Jang, Seon-Min; Yang, Su Chul

    2018-06-08

    Low-dimensional piezoelectric nanostructures such as nanoparticles, nanotubes, nanowires, nanoribbons and nanosheets have been developed for potential applications as energy harvesters, tunable sensors, functional transducers and low-power actuators. In this study, lead-free BaTiO 3 nanorod bundle arrays (NBA) with highly piezoelectric properties were successfully synthesized on fluorine-doped tin oxide (FTO) substrate via a two-step process consisting of TiO 2 epitaxial growth and BaTiO 3 conversion. Through the TiO 2 epitaxial growth on FTO substrate, (001) oriented TiO 2 nanostructures formed vertically-aligned NBA with a bundle diameter of 80 nm and an aspect ratio of six. In particular, chemical etching of the TiO 2 NBA was conducted to enlarge the surface area for effective Ba 2+ ion diffusion during the perovskite conversion process from TiO 2 to BaTiO 3 . The final structure of perovskite BaTiO 3 NBA was found to exhibit a feasible piezoelectric response of 3.56 nm with a clear phase change of 180° from the single BaTiO 3 bundle, by point piezoelectric forced microscopy (PFM) analysis. Consequently, highly piezoelectric NBA could be a promising nanostructure for various nanoscale electronic devices.

  13. Self-organized TiO2 nanotubular arrays for photoelectrochemical hydrogen generation: effect of crystallization and defect structures

    International Nuclear Information System (INIS)

    Mahajan, V K; Misra, M; Raja, K S; Mohapatra, S K

    2008-01-01

    The effect of crystallization and surface chemistry of nanotubular titanium dioxide (TiO 2 ) in connection with the photoelectrochemical process is reported in this investigation. TiO 2 nanotubular arrays were synthesized by a simple anodization process in an acidified fluoride electrolyte at room temperature. The TiO 2 nanotubes were amorphous in as-anodized condition; their transformation to crystalline phases was a function of annealing temperature and gaseous environment. The anatase phase was observed predominantly after annealing in non-oxidizing atmospheres, whereas annealing in an oxygen environment showed a mixture of anatase and rutile phases. X-ray photoelectron spectroscopy was used to determine the chemical environment of the surface, which revealed the presence of phosphate, oxygen vacancies and pentacoordinated Ti in hydrogen annealed samples. Diffuse reflectance photospectrometry of non-oxygen annealed samples showed long absorption tails extending in the visible region. The photoelectrochemical response of the TiO 2 nanotubes annealed in different conditions was investigated. Photoelectrochemical performance under simulated solar light was improved by annealing the nanotubular TiO 2 samples in non-oxidizing environment

  14. Enhancement of Dye-Sensitized Solar Cells Efficiency Using Mixed-Phase TiO2 Nanoparticles as Photoanode

    Directory of Open Access Journals (Sweden)

    Yi-Hua Fan

    2017-01-01

    Full Text Available Dye-sensitized solar cell (DSSC is a potential candidate to replace conventional silicon-based solar cells because of high efficiency, cheap cost, and lower energy consumption in comparison with silicon chip manufacture. In this report, mixed-phase (anatase and rutile nanoparticles TiO2 photoanode was synthesized to investigate material characteristics, carriers transport, and photovoltaic performance for future DSSC application. Field-emission scanning electron microscope (SEM, X-ray diffraction (XRD, photoluminescence (PL, and UV-visible spectroscopy were used to characterize mixed TiO2 particles. Subsequently, various mixed-phase TiO2 anodes in DSSC devices were measured by electrical impedance spectra (EIS and energy efficiency conversion. The overall energy conversion efficiency of DSSC chip was improved as a result of the increase of rutile phase of TiO2 (14% in anatase matrix. Synergistic effects including TiO2 crystallization, reduction of defect density level in energy band, longer lifetime of photoexcited electrons, and lower resistance of electron pathway all contributed to high efficiency of light energy conversion.

  15. Preparation and Tribological Properties of Dual-Coated TiO2 Nanoparticles as Water-Based Lubricant Additives

    Directory of Open Access Journals (Sweden)

    Yue Gu

    2014-01-01

    Full Text Available Titanium dioxide nanoparticles (TiO2 were synthesized and then dual-coated with silane coupling agent (KH-570 and OP-10 in sequence in order to be dispersed stably in water as lubricant additives. The tribological properties and the application performance in Q235 steel machining of the nanoparticles as water-based lubricant additives were investigated on an MSR-10D four-ball tribotester and on a bench drilling machine, respectively. Scanning electron microscope (SEM and atomic force microscope (AFM were used to analyze the worn surface. The results show that the surface-modified TiO2 nanoparticles can remarkably improve the load-carrying capacity, the friction reducing, and anti wear abilities of pure water. The wear scar diameter and the coefficient of friction of the water-based lubricating fluids with TiO2 nanoparticles decreased, and the thick deep furrows on the surface of wear scar also decreased obviously with the increase of TiO2 concentration. The power consumption in drilling process was lower and the cutting surface was smoother using the water-based lubricating fluids added TiO2 nanoparticles compared to the fluid without addition. The reason for nanoparticles improving tribological properties of water based lubricating fluid might be the formation of a dynamic deposition film during rubbing process according to analysis of the worn surface.

  16. Influence of Nd-Doping on Photocatalytic Properties of TiO2 Nanoparticles and Thin Film Coatings

    Directory of Open Access Journals (Sweden)

    Damian Wojcieszak

    2014-01-01

    Full Text Available Structural, optical, and photocatalytic properties of TiO2 and TiO2:Nd nanopowders and thin films composed of those materials have been compared. Titania nanoparticles with 1, 3, and 6 at. % of Nd-dopant were synthesized by sol-gel method. Additionally, thin films with the same material composition were prepared with the aid of spin-coating method. The analysis of structural investigations revealed that all as-prepared nanopowders were nanocrystalline and had TiO2-anatase structure. The average size of crystallites was ca. 4-5 nm and the correlation between the amount of neodymium and the size of TiO2 crystallites was observed. It was shown that the dopant content influenced the agglomeration of the nanoparticles. The results of photocatalytic decomposition of MO showed that doping with Nd (especially in the amount of 3 at. % increased self-cleaning activity of the prepared titania nanopowder. Similar effect was received in case of the thin films, but the decomposition rate was lower due to their smaller active surface area. However, the as-prepared TiO2:Nd photocatalyst in the form of thin films or nanopowders seems to be a very attractive material for various applications.

  17. Modified gas diffusion layer for fuel cells synthesized by pulsed laser ablation

    International Nuclear Information System (INIS)

    Ebrasu, Daniela; Stefanescu, Ioan; Dorcioman, Gabriela; Serban, Nicolae; Axente, Emil; Sima, Felix; Ristoscu, Carmen; Mihailescu, Ioan N.; Enculescu, Ionut

    2010-01-01

    Full text; In this paper there are presented the first results regarding the development of a modified gas diffusion layer for fuel cells consisting of a simple or teflonized carbon cloth deposited by pulsed laser with metal oxide nanostructures. These are designed to operate both as co-catalyst, and oxidic support for other electrochemically active catalysts. We selected TiO 2 , ZnO and Al 2 O 3 doped (2 wt.%) ZnO which were uniformly distributed over the surface of gas diffusion layers in order to improve the catalytic activity, stability and lifetime, and reduce the production costs of proton exchange membrane fuel cells. We evidenced by scanning electron microscopy and energy dispersive spectroscopy that our depositions consisted of TiO 2 nanoparticles while in the case of ZnO and Al 2 O 3 doped (2 wt.%) ZnO transparent quasicontinuous films were synthesized. (authors)

  18. Structural features and electrochemical properties of nanostructured ZnCo2O4 synthesized by an oxalate precursor method

    International Nuclear Information System (INIS)

    Kang, Wenpei; Feng, Fan; Zhang, Miaomiao; Liu, Shaojie; Shen, Qiang

    2013-01-01

    As a Li-ion battery anode, the active substance with a porous nanostructure can be endowed with a high electrochemical performance because of its porosity and remarkable surface area. In this paper, the thermal decomposition of zinc–cobalt binary oxalate precursors, precipitated from a solvothermal medium of ethanol and water (75/25, v/v) at 100 °C, has been performed to synthesize phase-pure ZnCo 2 O 4 spinels, thoroughly giving porous and rod-like configurations with an average length of a few micrometers. Interestingly, each of the as-obtained porous microrods has been well characterized to consist of ∼35.2-nm single-crystalline nanoparticles with polydisperse interspaces. More interestingly, porous ZnCo 2 O 4 microrods can deliver an initial specific discharge capacity of 1,293.7 mAh g −1 with the coulombic efficiency of 76.8 % at 0.2 A g −1 , reaching a value of 937.3 mAh g −1 over 100 discharge–charge cycles. Even at a high current density of 2.0 A g −1 , the porous ZnCo 2 O 4 nanostructures can still possess a reversible discharge capacity of ∼925.0 mAh g −1 , further assigned to the synergistic effect of Zn- and Co-based oxide components. Anyway, the facile oxalate precursor method can realize the controlling synthesis of porous and rod-like ZnCo 2 O 4 nanostructures with a high electrochemical performance

  19. Pore size is a critical parameter for obtaining sustained protein release from electrochemically synthesized mesoporous silicon microparticles

    Directory of Open Access Journals (Sweden)

    Ester L. Pastor

    2015-10-01

    Full Text Available Mesoporous silicon has become a material of high interest for drug delivery due to its outstanding internal surface area and inherent biodegradability. We have previously reported the preparation of mesoporous silicon microparticles (MS-MPs synthesized by an advantageous electrochemical method, and showed that due to their inner structure they can adsorb proteins in amounts exceeding the mass of the carrier itself. Protein release from these MS-MPs showed low burst effect and fast delivery kinetics with complete release in a few hours. In this work, we explored if tailoring the size of the inner pores of the particles would retard the protein release process. To address this hypothesis, three new MS-MPs prototypes were prepared by electrochemical synthesis, and the resulting carriers were characterized for morphology, particle size, and pore structure. All MS-MP prototypes had 90 µm mean particle size, but depending on the current density applied for synthesis, pore size changed between 5 and 13 nm. The model protein α-chymotrypsinogen was loaded into MS-MPs by adsorption and solvent evaporation. In the subsequent release experiments, no burst release of the protein was detected for any prototype. However, prototypes with larger pores (>10 nm reached 100% release in 24–48 h, whereas prototypes with small mesopores (<6 nm still retained most of their cargo after 96 h. MS-MPs with ∼6 nm pores were loaded with the osteogenic factor BMP7, and sustained release of this protein for up to two weeks was achieved. In conclusion, our results confirm that tailoring pore size can modify protein release from MS-MPs, and that prototypes with potential therapeutic utility for regional delivery of osteogenic factors can be prepared by convenient techniques.

  20. Proximity hybridization-regulated catalytic DNA hairpin assembly for electrochemical immunoassay based on in situ DNA template-synthesized Pd nanoparticles

    International Nuclear Information System (INIS)

    Zhou, Fuyi; Yao, Yao; Luo, Jianjun; Zhang, Xing; Zhang, Yu; Yin, Dengyang; Gao, Fenglei; Wang, Po

    2017-01-01

    Novel hybridization proximity-regulated catalytic DNA hairpin assembly strategy has been proposed for electrochemical immunoassay based on in situ DNA template-synthesized Pd nanoparticles as signal label. The DNA template-synthesized Pd nanoparticles were characterized with atomic force microscopic and X-ray photoelectron spectroscopy. The highly efficient electrocatalysis by DNA template synthesized Pd nanoparticles for NaBH 4 oxidation produced an intense detection signal. The label-free electrochemical method achieved the detection of carcinoembryonic antigen (CEA) with a linear range from 10 −15 to 10 −11  g mL −1 and a detection limit of 0.43 × 10 −15  g mL −1 . Through introducing a supersandwich reaction to increase the DNA length, the electrochemical signal was further amplified, leading to a detection limit of 0.52 × 10 −16  g mL −1 . And it rendered satisfactory analytical performance for the determination of CEA in serum samples. Furthermore, it exhibited good reproducibility and stability; meanwhile, it also showed excellent specificity due to the specific recognition of antigen by antibody. Therefore, the DNA template synthesized Pd nanoparticles based signal amplification approach has great potential in clinical applications and is also suitable for quantification of biomarkers at ultralow level. - Graphical abstract: A novel label-free and enzyme-free electrochemical immunoassay based on proximity hybridization-regulated catalytic DNA hairpin assemblies for recycling of the CEA. - Highlights: • A novel enzyme-free electrochemical immunosensor was developed for detection of CEA. • The signal amplification was based on catalytic DNA hairpin assembly and DNA-template-synthesized Pd nanoparticles. • The biosensor could detect CEA down to 0.52 × 10 −16  g mL −1 level with a dynamic range spanning 5 orders of magnitude.

  1. A novel single-step synthesis of N-doped TiO2 via a sonochemical method

    International Nuclear Information System (INIS)

    Wang, Xi-Kui; Wang, Chen; Guo, Wei-Lin; Wang, Jin-Gang

    2011-01-01

    Graphical abstract: The N-doped anatase TiO 2 nanoparticles were synthesized by sonochemical method. The as-prepared sample is characterized by XRD, TEM, XPS and UV-Vis DRS. The photocatalytic activity of the photocatalyst was evaluated by the photodegradation of an azo dye direct sky blue 5B. Highlights: → A novel singal-step sonochemical synthesis method for the preparation of anatase N-doped TiO 2 nanocrystalline at low temperature has been devoleped. → The as-prepared sample is characterized by XRD, TEM, XPS and UV-Vis DRS. → The photodegradation of azo dye direct sky blue 5 showed that the N-doped TiO 2 catalyst is of high visible-light photocatalytic activity. -- Abstract: A novel single-step synthetic method for the preparation of anatase N-doped TiO 2 nanocrystalline at low temperature has been devoleped. The N-doped anatase TiO 2 nanoparticles were synthesized by sonication of the solution of tetraisopropyl titanium and urea in water and isopropyl alcohol at 80 o C for 150 min. The as-prepared sample was characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and UV-vis absorption spectrum. The product structure depends on the reaction temperature and reaction time. The photocatalytic activity of the as-prepared photocatalyst was evaluated via the photodegradation of an azo dye direct sky blue 5B. The results show that the N-doped TiO 2 nanocrystalline prepared via sonication exhibit an excellent photocatalytic activity under UV light and simulated sunlight.

  2. Synthesis, characterization and photocatalytic activity of WO3/TiO2 for NO removal under UV and visible light irradiation

    International Nuclear Information System (INIS)

    Luévano-Hipólito, E.; Martínez-de la Cruz, A.; López-Cuellar, E.; Yu, Q.L.; Brouwers, H.J.H.

    2014-01-01

    Samples with different proportions WO 3 /TiO 2 were prepared by co-precipitation method followed by a heat treatment. The samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS), and adsorption–desorption N 2 isotherms (BET). The photocatalytic properties of WO 3 /TiO 2 samples were evaluated in the photo-oxidation reaction of nitric oxide (NO) under UV and visible light irradiation. The highest photocatalytic activity was observed in the WO 3 /TiO 2 sample with a composition of 80% mole of TiO 2 . Among the different substrates used for supporting the photocatalyst, the best results were reached over concrete and glass when it was exposed to UV and visible light irradiation, respectively. In overall, the photocatalytic efficiency of the synthesized materials was higher under UV than visible light irradiation. - Highlights: • WO 3 /TiO 2 prepared in simple way show high photocatalytic activity for NO removal. • The concrete was the best substrate to the performance of WO 3 /TiO 2 with UV radiation. • The glass was the best substrate to the performance of WO 3 /TiO 2 with visible radiation

  3. Synergic effect of the TiO2-CeO2 nanoconjugate system on the band-gap for visible light photocatalysis

    International Nuclear Information System (INIS)

    Contreras-García, M.E.; García-Benjume, M. Lorena; Macías-Andrés, Víctor I.; Barajas-Ledesma, E.; Medina-Flores, A.; Espitia-Cabrera, M.I.

    2014-01-01

    Graphical abstract: - Highlights: • Nanostructured TiO 2 -CeO 2 films are successfully synthesized by combining of sputtering and electrophoresis methods. • Synergic effect of CeO 2 on TiO 2 band gap was demonstrated, CeO 2 diminishes it from 3.125 to 2.74. • Morphologic characterization of the nanoconjugate TiO 2 -CeO 2 films by different microscopy techniques. - Abstract: The TiO 2 -CeO 2 photocatalytic system in films is proposed here, in order to obtain photocatalytic systems that can be excited by solar light. The films were obtained through the electrophoretic deposition (EPD) of TiO 2 -CeO 2 gel on sputtered Ti Corning glass substrates. The synergic effect of CeO 2 in TiO 2 films was analyzed as a function of the optical band gap reduction at different concentrations (1, 5, 10, and 15 mol%). The effect of two thermal treatments was also evaluated. The lowest band gap value was obtained for the sample with 5 mol% ceria that was thermally treated at 700 °C. The nanostructured films were characterized by Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high angle annular dark field (HAADF), high resolution transmission electron microscopy (HRTEM), and atomic force microscopy (AFM). The nanocomposites were formed by TiO 2 and CeO 2 nanoparticles in the anatase and fluorite type phases, respectively

  4. Enhanced supercapacitor performance using hierarchical TiO2 nanorod/Co(OH)2 nanowall array electrodes

    International Nuclear Information System (INIS)

    Ramadoss, Ananthakumar; Kim, Sang Jae

    2014-01-01

    Graphical abstract: - Highlights: • TiO 2 /Co(OH) 2 hierarchical nanostructure was prepared by a combination of hydrothermal and cathodic electrodeposition method. • Hierarchical nanostructure electrode exhibited a maximum capacitance of 274.3 mF cm −2 at a scan rate of 5 mV s −1 . • Combination of Co(OH) 2 nanowall with TiO 2 NR into a single system enhanced the electrochemical behavior of supercapacitor electrode. - Abstract: We report novel hierarchical TiO 2 nanorod (NR)/porous Co(OH) 2 nanowall array electrodes for high-performance supercapacitors fabricated using a two-step process that involves hydrothermal and electrodeposition techniques. Field-emission scanning electron microscope images reveal a bilayer structure consisting of TiO 2 NR arrays with porous Co(OH) 2 nanowalls. Compared with the bare TiO 2 NRs, the hierarchical TiO 2 NRs/Co(OH) 2 electrodes showed improved pseudocapacitive performance in a 2-M KOH electrolyte solution, exhibiting an areal specific capacitance of 274.3 mF cm −2 at a scan rate of 5 mV s −1 . The electrodes exhibited good stability, retaining 82.5% of the initial capacitance after 4000 cycles. The good pseudocapacitive performance of the hierarchical nanostructures is mainly due to the porous structure, which provides fast ion and electron transfer, a large surface area, short ion diffusion paths, and a favourable volume change during the cycling process

  5. Adhesion measurement of highly-ordered TiO2 nanotubes on Ti-6Al-4V alloy

    Directory of Open Access Journals (Sweden)

    Masoud Sarraf

    2017-12-01

    Full Text Available Self-assembled nanotubular arrays on Ti alloys could be used for more effective implantable devices in various medical approaches. In the present work, the adhesion of TiO2 nanotubes (TiO2 NTs on Ti-6Al-4V (Ti64 was investigated by laser spallation and scratch test techniques. At first, electrochemical anodization was performed in an ammonium fluoride solution dissolved in a 90:10 ethane-1,2-diol (ethylene glycol and water solvent mixture. This process was performed at room temperature (23 °C at a steady potential of 60 V for 1 h. Next, the TiO2 nanotubes layer was heat-treated to improve the adhesion of the coating. The formation of selforganized TiO2 nanotubes as well as the microstructural evolution, are strongly dependent on the processing parameters and subsequent annealing. From microscopic analysis, highly oriented arrays of TiO2 nanotubes were grown by thermal treatment for 90 min at 500 °C. Further heat treatment above 500 °C led to the detachment of the nanotubes and the complete destruction of the nanotubes occurred at temperature above 700 °C. Scratch test analysis over a constant scratch length (1000 µm indicated that the failure point was shifted from 247.4 to 557.9 µm while the adhesion strength was increased from ∼862 to ∼1814 mN after annealing at 500 °C. The adhesion measurement determined by laser spallation technique provided an intrinsic adhesion strength of 51.4 MPa for the TiO2 nanotubes on the Ti64 substrate.

  6. Dye-sensitized solar cells based on anatase TiO2/multi-walled carbon nanotubes composite nanofibers photoanode

    International Nuclear Information System (INIS)

    Du, Pingfan; Song, Lixin; Xiong, Jie; Li, Ni; Wang, Lijun; Xi, Zhenqiang; Wang, Naiyan; Gao, Linhui; Zhu, Hongliang

    2013-01-01

    Highlights: ► TiO 2 /multi-walled carbon nanotubes (MWCNTs) hybrid nanofibers are prepared via electrospinning. ► Dye-sensitized solar cells (DSSCs) are assembled using TiO 2 /MWCNTs nanofibers film as photoanode. ► Energy conversion efficiency of DSSCs is greatly dependent on the content of MWCNTs. ► Moderate MWCNTs incorporation can substantially enhance the performance of DSSCs. - Abstract: Anatase TiO 2 /multi-walled carbon nanotubes (TiO 2 /MWCNTs) hybrid nanofibers (NFs) film was prepared via a facile electrospinning method. Dye-sensitized solar cells (DSSCs) based on TiO 2 /MWCNTs composite NFs photoanodes with different contents of MWCNTs (0, 0.1, 0.3, 0.5, 1 wt.%) were assembled using N719 dye as sensitizer. Field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), X-ray diffractometer (XRD), and Raman spectrometer were used to characterize the TiO 2 /MWCNTs electrode films. The photocurrent–voltage (I–V) characteristic, incident photo-to-current conversion efficiency (IPCE) spectrum, and electrochemical impedance spectroscopy (EIS) measurements were carried out to evaluate the photoelectric properties of the DSSCs. The results reveal that the energy conversion efficiency is greatly dependent on the content of MWCNTs in the composite NFs film, and a moderate incorporation of MWCNTs can substantially enhance the performance of DSSCs. When the electrode contains 0.3 wt.% MWCNTs, the corresponding solar cell yield the highest efficiency of 5.63%. This efficiency value is approximately 26% larger than that of the unmodified counterpart.

  7. Hierarchical (0 0 1) facet anatase/rutile TiO2 heterojunction photoanode with enhanced photoelectrocatalytic performance

    International Nuclear Information System (INIS)

    Tian, Hongyi; Zhao, Guohua; Zhang, Ya-nan; Wang, Yanbin; Cao, Tongcheng

    2013-01-01

    Highlights: ► (0 0 1) facet TiO 2 photoanode with large surface area is reported for the first time. ► Ordered heterojunction further improves light absorption in (0 0 1) facet TiO 2 system. ► (0 0 1) facet TiO 2 photoanode possesses promoted photoelectrocatalytic performance. ► Photoelectrical enhancement mechanism is clarified by electrochemical methods. ► Photogenerated carrier and lifetime are remarkably enhanced by ingenious design. -- Abstract: A hierarchical heterojunction TiO 2 photoanode with large surface/body ratio is reported to exhibit high oxidation activity due to the constructing of anatase TiO 2 with exposed (0 0 1) facets. The mixed-phase photoanode is fabricated through surfactant-assisted anchoring ultrathin anatase nanosheets on vertically ordered rutile nanorod arrays. This cactaceae-like TiO 2 possesses high-exposed (0 0 1) facets outer layer, large specific surface area (375 m 2 g −1 ), efficient photo-to-current conversion (8.2%) and excellent photocatalytic ability to degrade bisphenol A. The greatly promoted photoelectric and photocatalytic performance results from the synergetic effects of the architecture design of high-active (0 0 1) facets and hierarchical heterojunctions. The mechanism analysis reveals that the remarkable increase of photogenerated carrier concentration (2.40 × 10 22 cm −3 ) improves photocatalytic activity, by virtue of constructing staggered energy levels, suppressing the recombination of electrons and holes, and extending the electron lifetime (133 ms)

  8. A practical pathway for the preparation of Fe_2O_3 decorated TiO_2 photocatalyst with enhanced visible-light photoactivity

    International Nuclear Information System (INIS)

    Cheng, Li; Qiu, Shoufei; Chen, Juanrong; Shao, Jian; Cao, Shunsheng

    2017-01-01

    Shifting the ultra-violet of titania to visible light driven photocatalysis can be realized by coupling with metallic or non-metallic elements. However, time-consuming multi-step process and significant loss of UV photocatalytic activity of such TiO_2-based photocatalysts severely hinder their practical applications. In this work, we explore the idea of creating a practical method for the preparation of Fe_2O_3 decorated TiO_2 (TiO_2/Fe_2O_3) photocatalyst with controlled visible-light photoactivity. This method only involves the calcination of the mixture (commercial P25 powders and magnetic Fe_3O_4 nanoparticles) prepared by a mechanical process. The morphology and properties of TiO_2/Fe_2O_3 composites were characterized by Transmission electron microscope, X-ray diffraction, UV–vis spectroscopy, and X-ray photoelectron spectroscopy. Results confirm the fusion of TiO_2 and Fe_2O_3, which promotes photo-generated electrons/holes migration and separation. Because of the strong synergistic effect, the as-synthesized TiO_2/Fe_2O_3 composites manifest an enhanced visible-light photocatalytic activity. Especially, the TiO_2/Fe_2O_3 photocatalyst is very easy to be constructed via an one-step protocol that efficiently overcomes the time-consuming multi-step processes used in existed strategies for the preparation of Fe_2O_3/TiO_2 photocatalysts, providing a new insight into the practical application of TiO_2/Fe_2O_3 visible light photocatalyst. - Highlights: • We introduced a practical preparation of Fe_2O_3 decorated TiO_2 photocatalyst. • TiO_2/Fe_2O_3 was developed using commercial precursors in a high efficient manner. • Visible-light activity of TiO_2/Fe_2O_3 could be tuned by changing amount of Fe_3O_4 precursor. • TiO_2/Fe_2O_3 exhibited a higher visible-light photocatalytic activity than P25.

  9. Natural dye sensitizer from cassava (Manihot utilissima) leaves extract and its adsorption onto TiO2 photo-anode

    Science.gov (United States)

    Nurlela; Wibowo, R.; Gunlazuardi, J.

    2017-04-01

    Interaction between TiO2 and dyes sensitizer have been studied. The chlorophyll presents in the crude leave extract (CLE-dye) from cassava (Manihot utilissima) was immobilized on to the photo-anode, consists of TiO2 supported by fluor doped Tin oxide (SnO2-F) Glass. The TiO2 was prepared by Rapid Breakdown Anodization (RBA) method then immobilized on to glass coated by SnO2-F using doctor blade technique, to give CLE-dye/TiO2/SnO2-F/Glass photo-anode. The prepared photo-anode was characterized by UV-Vis-DRS, FTIR, XRD, SEM, electrochemical and spectro-electrochemical systems. In this study, the HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) energy level of the CLE-dye were empirically determined by cyclic voltammetry method, while spectro-electro-chemistry method was used to determine the coefficient of degradation and formation of the dyes, and diffusion coefficient of the hole recombination as well. Good anchoring between TiO2 with dye extracts (CLE-dye) can be seen from value of dye LUMO energy level (-4.26 eV), which is approaching the conduction band of TiO2 (-4.3 eV). The coefficient of degradation and formation of the CLE-dye showed a quasi reversible and diffusion coefficient hole recombination values were small, indicated that it is quite suitable as a sensitizer in a dyes sensitized solar cell.

  10. Designed fabrication of fluorine-doped carbon coated mesoporous TiO2 hollow spheres for improved lithium storage

    International Nuclear Information System (INIS)

    Geng, Hongbo; Ming, Hai; Ge, Danhua; Zheng, Junwei; Gu, Hongwei

    2015-01-01

    Graphical abstract: Hollow TiO 2 with mesoporous shell (MHTO) was successfully fabricated by a novel and controllable route, followed by fluorine-doped carbon coating the MHTO (MHTO-C/F), with the aim of enhancing the conductivity and stability of structures. - Highlights: • Anatase TiO 2 hollow spheres with mesoporous shells (MHTO) was fabricated via a facile and controllable route, to improve the lithium ion mobility as well as the stability of the architecture. • Fluorine-doped carbon derived from polyvinylidene difluoride was further encapsulated onto TiO 2 hollow spheres to improve the conductivity. • The composites could provide excellent electrochemical performance, which was desirable for the application of TiO 2 as an anode material in lithium ion batteries. - Abstract: In this manuscript, we demonstrated a facile route for the controllable design of “Fluorine (F)-doped carbon” (C/F)-treated TiO 2 hollow spheres with mesoporous shells (MHTO-C/F). The fabrication of this distinct mesoporous hollow structures and the C/F coating could effectively improve the electrolyte permeability and architectural stability, as well as electrical conductivity and lithium ion mobility. As anticipated, MHTO-C/F has several remarkable electrochemical properties, such as a high specific reversible capacity of 252 mA h g −1 , outstanding cycling stability of more than 210 mA h g −1 after 100 cycles at 0.5 C, and good rate performance of around 123 mA h g −1 at 5 C (1 C = 168 mA g −1 ). These properties are highly beneficial for lithium storage

  11. Nanoscale Optimization and Statistical Modeling of Photoelectrochemical Water Splitting Efficiency of N-Doped TiO2 Nanotubes

    KAUST Repository

    Isimjan, Tayirjan T.

    2014-12-19

    Highly ordered nitrogen-doped titanium dioxide (N-doped TiO2) nanotube array films with enhanced photo-electrochemical water splitting efficiency (PCE) for hydrogen generation were fabricated by electrochemical anodization, followed by annealing in a nitrogen atmosphere. Morphology, structure and composition of the N-doped TiO2 nanotube array films were investigated by FE-SEM, XPS, UV-Vis and XRD. The effect of annealing temperature, heating rate and annealing time on the morphology, structure, and photo-electrochemical property of the N-doped TiO2 nanotube array films were investigated. A design of experiments method was applied in order to minimize the number of experiments and obtain a statistical model for this system. From the modelling results, optimum values for the influential factors were obtained in order to achieve the maximum PCE. The optimized experiment resulted in 7.42 % PCE which was within 95 % confidence interval of the predicted value by the model. © 2014 Springer Science+Business Media.

  12. A detailed study on the working mechanism of a heteropoly acid modified TiO2 photoanode for efficient dye-sensitized solar cells.

    Science.gov (United States)

    Jiang, Yanxia; Yang, Yulin; Qiang, Liangsheng; Fan, Ruiqing; Li, Liang; Ye, Tengling; Na, Yong; Shi, Yan; Luan, Tianzhu

    2015-03-14

    A novel heteropolyacid (HPA) K6SiW11O39Ni(H2O)·xH2O (SiW11Ni) modified TiO2 has been successfully synthesized and introduced into the photoanode of dye-sensitized solar cells (DSSCs). The performance of the cell with the HPA-modified photoanode (SiW11Ni/TiO2), mixed with P25 powder in the ratio of 2 : 8, is better than the cell with a pristine P25 photoanode. An increase of 31% in the photocurrent and 22% improvement in the conversion efficiency are obtained. The effect of the heteropolyacid was well studied by UV-vis spectroscopy, spectro-electrochemical spectroscopy, dark current, intensity-modulated photocurrent spectroscopy and intensity-modulated photovoltage spectroscopy, open-circuit voltage decay and electrochemical impedance spectroscopy. The results show that the interfacial layer modified by SiW11Ni can enhance the injection and transport of electrons, and then retard the recombination of electrons, which results in a longer electron lifetime. What's more, the introduction of SiW11Ni can simultaneously broaden the absorption in the visible region, eventually leading to an efficient increase in energy conversion efficiency.

  13. 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.

  14. TiO2-ITO and TiO2-ZnO nanocomposites: application on water treatment

    Directory of Open Access Journals (Sweden)

    Bessais B.

    2012-06-01

    Full Text Available One of the most promising ideas to enhance the photocatalytic efficiency of the TiO2 is to couple this photocatalyst with other semiconductors. In this work, we report on the development of photo-catalytic properties of two types of composites based on TiO2 – ITO (Indium Tin Oxide and TiO2 – ZnO deposited on conventional ceramic substrates. The samples were characterized by X-ray diffraction (XRD and transmission Electron Microscopy (TEM. The photo-catalytic test was carried out under UV light in order to reduce/oxidize a typical textile dye (Cibacron Yellow. The experiment was carried out in a bench scale reactor using a solution having a known initial dye concentration. After optimization, we found that both nanocomposites exhibit better photocatalytic activity compared to the standard photocatalyst P25 TiO2.

  15. Performance of electrodes synthesized with polyacrylonitrile-based carbon nanofibers for application in electrochemical sensors and biosensors

    Energy Technology Data Exchange (ETDEWEB)

    Adabi, Mahdi [Department of Medical Nanotechnology, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Saber, Reza [Department of Medical Nanotechnology, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Center of Excellence in Electrochemistry, Faculty of Chemistry, University of Tehran, Tehran (Iran, Islamic Republic of); Faridi-Majidi, Reza, E-mail: refaridi@sina.tums.ac.ir [Department of Medical Nanotechnology, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Center of Excellence in Electrochemistry, Faculty of Chemistry, University of Tehran, Tehran (Iran, Islamic Republic of); Faridbod, Farnoush [Science and Technology in Medicine (RCSTIM), Tehran University of Medical Sciences, Tehran, Iran. (Iran, Islamic Republic of)

    2015-03-01

    The purpose of this work was to investigate the performance of electrodes synthesized with Polyacrylonitrile-based carbon nanofibers (PAN-based CNFs). The homogenous PAN solutions with different concentrations were prepared and electrospun to acquire PAN nanofibers and then CNFs were fabricated by heat treatment. The effective parameters for the production of electrospun CNF electrode were investigated. Scanning electron microscopy (SEM) was used to characterize electrospun nanofibers. Cyclic voltammetry was applied to investigate the changes of behavior of electrospun CNF electrodes with different diameters. The structure of CNFs was also evaluated via X-ray diffraction (XRD) and Raman spectroscopy. The results exhibited that diameter of nanofibers reduced with decreasing polymer concentration and applied voltage and increasing tip-to-collector distance, while feeding rate did not have significant effect on nanofiber diameter. The investigations of electrochemical behavior also demonstrated that cyclic voltammetric response improved as diameter of CNFs electrode decreased. - Highlights: • Electrospun CNFs can be directly used as working electrode. • Cyclic voltammetric response improved as diameter of CNFs electrode decreased. • The diameter of nanofibers reduced with decreasing polymer concentration. • The diameter of nanofibers reduced with decreasing applied voltage. • The diameter of nanofibers reduced with increasing tip-to-collector distance.

  16. Performance of electrodes synthesized with polyacrylonitrile-based carbon nanofibers for application in electrochemical sensors and biosensors

    International Nuclear Information System (INIS)

    Adabi, Mahdi; Saber, Reza; Faridi-Majidi, Reza; Faridbod, Farnoush

    2015-01-01

    The purpose of this work was to investigate the performance of electrodes synthesized with Polyacrylonitrile-based carbon nanofibers (PAN-based CNFs). The homogenous PAN solutions with different concentrations were prepared and electrospun to acquire PAN nanofibers and then CNFs were fabricated by heat treatment. The effective parameters for the production of electrospun CNF electrode were investigated. Scanning electron microscopy (SEM) was used to characterize electrospun nanofibers. Cyclic voltammetry was applied to investigate the changes of behavior of electrospun CNF electrodes with different diameters. The structure of CNFs was also evaluated via X-ray diffraction (XRD) and Raman spectroscopy. The results exhibited that diameter of nanofibers reduced with decreasing polymer concentration and applied voltage and increasing tip-to-collector distance, while feeding rate did not have significant effect on nanofiber diameter. The investigations of electrochemical behavior also demonstrated that cyclic voltammetric response improved as diameter of CNFs electrode decreased. - Highlights: • Electrospun CNFs can be directly used as working electrode. • Cyclic voltammetric response improved as diameter of CNFs electrode decreased. • The diameter of nanofibers reduced with decreasing polymer concentration. • The diameter of nanofibers reduced with decreasing applied voltage. • The diameter of nanofibers reduced with increasing tip-to-collector distance

  17. Preparation and Photocatalytic Activity of Nitrogen-doped Nano TiO2/Tourmaline Composites

    Directory of Open Access Journals (Sweden)

    LIU Xin-wei

    2016-06-01

    Full Text Available Using Ti(OC4H94 as precursor, CO(NH22 as nitrogen source, tourmaline as support, the nitrogen-doped nano TiO2/tourmaline composites were synthesized by sol-gel method with ultrasound assisted.The structure and performance of composites were characterized by XRD, FT-IR, UV-Vis DRS, SEM, EDS.The effects of calcining temperature, nitrogen-doped content, tourmaline amount, catalyst system on the photocatalytic activity of nitrogen-doped nano TiO2/tourmaline composites were studied.The results show that the photocatalytic activity of nitrogen-doped nano TiO2/tourmaline composites calcined under 500℃, the nitrogen doped amount of 5% (mole fraction, tourmaline added in an amount of 10% (mass fraction, catalyst dosage of 3g/L, under 500W UV light irradiation conditions, the photocatalytic degradation effect of TNT(10mg/L is the best, and has a good recycling performance.

  18. Removal of Crotamiton from Reverse Osmosis Concentrate by a TiO2/Zeolite Composite Sheet

    Directory of Open Access Journals (Sweden)

    Qun Xiang

    2017-07-01

    Full Text Available Reverse osmosis (RO concentrate from wastewater reuse facilities contains concentrated emerging pollutants, such as pharmaceuticals. In this research, a paper-like composite sheet consisting of titanium dioxide (TiO2 and zeolite was synthesized, and removal of the antipruritic agent crotamiton from RO concentrate was studied using the TiO2/zeolite composite sheet. The RO concentrate was obtained from a pilot-scale municipal secondary effluent reclamation plant. Effective immobilization of the two powders in the sheet made it easy to handle and to separate the photocatalyst and adsorbent from purified water. The TiO2/zeolite composite sheet showed excellent performance for crotamiton adsorption without obvious inhibition by other components in the RO concentrate. With ultraviolet irradiation, crotamiton was simultaneously removed through adsorption and photocatalysis. The photocatalytic decomposition of crotamiton in the RO concentrate was significantly inhibited by the water matrix at high initial crotamiton concentrations, whereas rapid decomposition was achieved at low initial crotamiton concentrations. The major degradation intermediates were also adsorbed by the composite sheet. This result provides a promising method of mitigating secondary pollution caused by the harmful intermediates produced during advanced oxidation processes. The cyclic use of the HSZ-385/P25 composite sheet indicated the feasibility of continuously removing crotamiton from RO concentrate.

  19. Low temperature fabrication of V-doped TiO2 nanoparticles, structure and photocatalytic studies

    International Nuclear Information System (INIS)

    Liu Baoshun; Wang Xuelai; Cai Guofa; Wen Liping; Song Yanbao; Zhao Xiujian

    2009-01-01

    V-doped TiO 2 nanoparticles were synthesized at low temperature and characterized by X-ray diffraction (XRD), Raman spectroscopy (RS), transmission electron microscopy (TEM), Brunauer-Emmet-Teller (BET), X-ray photoelectron spectroscopy (XPS), UV-vis spectroscopy, and photoluminescence (PL) spectroscopy, respectively. It is found the nanoparticle shape changed from needle, to short stick and then to cubic with the increase of doped V concentration, which was also accompanied by the improvement of crystallinity. The specific surface area (S BET ) decreased with increasing V content. It is confirmed that V ions can be doped in TiO 2 by substituting Ti 4+ ions, which suppressed the CB → VB and surface recombination of photoinduced electrons and holes, and a relation was found between the PL spectra and the UV photocatalytic activity. There was an optimum V content for the V-doped TiO 2 to present the best UV-light induced photoactivity, but they were visible-inactive. At last, the effect of the doping V as trapping centers on photocatalysis was investigated in detail, and used to explain the difference between the photocatalysis under the illumination of UV light and visible light.

  20. N, Fe and WO3 modified TiO2 for degradation of formaldehyde

    International Nuclear Information System (INIS)

    Tong Haixia; Zhao Li; Li Dan; Zhang Xiongfei

    2011-01-01

    Graphical abstract: The undoped TiO 2 powder (T(0)) shows strong photoabsorption only at wavelengths shorter than 400 nm, and while Fe 3+ and N-doped TiO 2 nanoparticles show photoabsorption in visible region and the absorption edge shifts to a longer wavelength. WO 3 compounding also benefits the photoabsorption in visible region. Display Omitted Highlights: → The preparation of the catalysts co-doped by Fe, N and compounded by WO 3 . → The obvious sculptured 'pattern' of the catalysts doped by Fe in the SEM images. → Strengthened photoabsorption to visible light of the modified catalysts from UV-DRS analysis. - Abstract: Butyltitanate, ethanol and glacial acetic acid were chosen as titanium source, solvent and chelating agent, respectively, via a sol-gel method combined impregnation method to prepare N, Fe co-doped and WO 3 compounded photocatalyst TiO 2 powder. The synthesized products were characterized by X-ray diffraction (XRD), diffuse reflectance UV-Vis spectra (UV-DRS), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Photocatalytic degradation of formaldehyde was employed to investigate the catalytic activity. The results show that the degradation rate is 77.61% in 180 min under UV light irradiation when the concentration of N is fixed on, and the optimum proportioning ratio of n(Fe):n(W):n(Ti) is 0.5:2:100.