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Sample records for carbon nanotube-doped tio2

  1. Synthesis and Characterization Carbon Nanotubes Doped Carbon Aerogels

    Science.gov (United States)

    Xu, Yuelong; Yan, Meifang; Liu, Zhenfa

    2017-12-01

    Polycondensation of phloroglucinol, resorcinol and formaldehyde with carbon nanotube (CNT) as the additives, using sodium carbonate as the catalyst, leads to the formation of CNT - doped carbon aerogels. The structure of carbon aerogels (CAs) with carbon nanotubes (CNTs) were characterized by X-ray diffraction and scanning electron microscopy. The specific surface area, pore size distribution and pore volume were measured by surface area analyzer. The results show that when the optimum doping dosage is 5%, the specific surface area of CNT - doped carbon aerogel is up to 665 m2 g-1 and exhibit plentiful mesoporous.

  2. A Fumonisins Immunosensor Based on Polyanilino-Carbon Nanotubes Doped with Palladium Telluride Quantum Dots

    Science.gov (United States)

    Masikini, Milua; Mailu, Stephen N.; Tsegaye, Abebaw; Njomo, Njagi; Molapo, Kerileng M.; Ikpo, Chinwe O.; Sunday, Christopher Edozie; Rassie, Candice; Wilson, Lindsay; Baker, Priscilla G. L.; Iwuoha, Emmanuel I.

    2015-01-01

    An impedimetric immunosensor for fumonisins was developed based on poly(2,5-dimethoxyaniline)-multi-wall carbon nanotubes doped with palladium telluride quantum dots onto a glassy carbon surface. The composite was assembled by a layer-by-layer method to form a multilayer film of quantum dots (QDs) and poly(2,5-dimethoxyaniline)-multi-wall carbon nanotubes (PDMA-MWCNT). Preparation of the electrochemical immunosensor for fumonisins involved drop-coating of fumonisins antibody onto the composite modified glassy carbon electrode. The electrochemical impedance spectroscopy response of the FB1 immunosensor (GCE/PT-PDMA-MWCNT/anti-Fms-BSA) gave a linear range of 7 to 49 ng L−1 and the corresponding sensitivity and detection limits were 0.0162 kΩ L ng−1 and 0.46 pg L−1, respectively, hence the limit of detection of the GCE/PT-PDMA-MWCNT immunosensor for fumonisins in corn certified material was calculated to be 0.014 and 0.011 ppm for FB1, and FB2 and FB3, respectively. These results are lower than those obtained by ELISA, a provisional maximum tolerable daily intake (PMTDI) for fumonisins (the sum of FB1, FB2, and FB3) established by the Joint FAO/WHO expert committee on food additives and contaminants of 2 μg kg−1 and the maximum level recommended by the U.S. Food and Drug Administration (FDA) for protection of human consumption (2–4 mg L−1). PMID:25558993

  3. Immobilization of TiO2 nanoparticles on Fe-filled carbon nanocapsules for photocatalytic applications

    International Nuclear Information System (INIS)

    Huang, H.-C.; Huang, G.-L.; Chen, H.-L.; Lee, Y.-D.

    2006-01-01

    Using a simple sol-gel method, a novel magnetic photocatalyst was produced by immobilization of TiO 2 nano-crystal on Fe-filled carbon nanocapsules (Fe-CNC). High resolution TEM images indicated that the immobilization of TiO 2 on Fe-CNC was driven primarily by heterogeneous coagulation, whereas surface nucleation and growth was the dominant mechanism for immobilizing TiO 2 on acid-functionalized hollow CNC. The TiO 2 immobilized on Fe-CNC exhibited the anatase phase as revealed by the X-ray diffraction (XRD) patterns. In comparison with free TiO 2 and TiO 2 -coated CNC, TiO 2 -coated Fe-CNC displayed good performance in the removal of NO gas under UV exposure. Due to the advantages of easy recycling and good photocatalytic efficiency, the novel magnetic photocatalyst developed here has potential use in photocatalytic applications for pollution prevention

  4. Carbon and TiO_2 synergistic effect on methylene blue adsorption

    International Nuclear Information System (INIS)

    Simonetti, Evelyn Alves Nunes; Simone Cividanes, Luciana de; Campos, Tiago Moreira Bastos; Rossi Canuto de Menezes, Beatriz; Brito, Felipe Sales; Thim, Gilmar Patrocínio

    2016-01-01

    Due to its high efficiency, low cost and a simple operation, the adsorption process is an important and widely used technique for industrial wastewater treatment. Recent studies on the removal of artificial dyes by adsorption include a large number of adsorbents, such as: activated carbon, silicates, carbon nanotube, graphene, fibers, titanates and doped titanates. The carbon insertion in the TiO_2 structure promotes a synergistic effect on the adsorbent composite, improving the adsorption and the charge-transfer efficiency rates. However, there are few studies regarding the adsorption capacity of TiO_2/Carbon composites with the carbon concentration. This study evaluates the effect of carbon (resorcinol/formaldehyde) insertion on TiO_2 structure through the adsorption process. Adsorbents were prepared by varying the carbon weight percentages using the sol-gel method. The physicochemical properties of the catalysts prepared, such as crystallinity, particle size, surface morphology, specific surface area and pore volume were investigated. The kinetic study, adsorption isotherm, pH effect and thermodynamic study were examined in batch experiments using methylene blue as organic molecule. In addition, the effect of carbon phase on the adsorption capacity of TiO_2-carbon composite was deeply investigated. SEM micrographs showed that TiO_2 phase grows along the carbon phase and FT-IR results showed the presence of Ti−O−C chemical bonding. The experiments indicate that the carbon phase acted as a nucleation agent for the growth of TiO_2 during the sol-gel step, with a TiO_2 structure suitable for blue methylene adsorption, resulting in a material with large surface area and slit-like or wedge-shaped pores. Further experiments will show the best carbon concentration for methylene blue adsorption using a TiO_2 based material. - Highlights: • This article deals with the adsorption of methylene blue onto TiO_2-Carbon composite. • The sol-gel synthesis was efficient

  5. 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.

  6. Synthesis and Photocatalytic Activity of Anatase TiO2 Nanoparticles-coated Carbon Nanotubes

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    Xie Yi

    2009-01-01

    Full Text Available Abstract A simple and straightforward approach to prepare TiO2-coated carbon nanotubes (CNTs is presented. Anatase TiO2 nanoparticles (NPs with the average size ~8 nm were coated on CNTs from peroxo titanic acid (PTA precursor even at low temperature of 100 °C. We demonstrate the effects of CNTs/TiO2 molar ratio on the adsorption capability and photocatalytic efficiency under UV–visible irradiation. The samples showed not only good optical absorption in visible range, but also great adsorption capacity for methyl orange (MO dye molecules. These properties facilitated the great enhancement of photocatalytic activity of TiO2 NPs-coated CNTs photocatalysts. The TiO2 NPs-coated CNTs exhibited 2.45 times higher photocatalytic activity for MO degradation than that of pure TiO2.

  7. Preparation and performance of photocatalytic TiO2 immobilized on palladium-doped carbon fibers

    International Nuclear Information System (INIS)

    Zhu Yaofeng; Fu Yaqin; Ni Qingqing

    2011-01-01

    Pd-modified carbon fibers (CFs) are obtained by a facile oxidation-reduction method and then dip-coated in a sol-gel of titanium dioxide (TiO 2 ) to form supported TiO 2 /Pd-CF photocatalysts. The morphology of the Pd-modified CFs and the amount Pd deposited are characterized by field emission scanning electron microscopy and atomic absorption spectrometry, respectively. X-ray diffraction is used to investigate the crystal structures of the TiO 2 photocatalyst. Acid orange II is used as a model contaminant to evaluate the photocatalytic properties of the photocatalyst under UV irradiation. TiO 2 /Pd-CF exhibits higher catalytic activity than TiO 2 /CF towards the degradation of acid orange II. Optimum photocatalytic performance and support properties are achieved when the Pd particle loading is about 10.8 mg/g.

  8. ELECTROPHORETIC DEPOSITION OF TIO2-MULTI-WALLED CARBON NANOTUBE COMPOSITE COATINGS: MORPHOLOGICAL STUDY

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    M. S. MAHMOUDI JOZEE

    2016-09-01

    Full Text Available A homogenous TiO2 / multi-walled carbon nanotubes(MWCNTs composite film were prepared by electrophoretic co-deposition from organic suspension on a stainless steel substrate.  In this study, MWCNTs was incorporated to the coating because of their long structure and their capability to be functionalized by different inorganic groups on the surface. FTIR spectroscopy showed the existence of carboxylic groups on the modified carbon nanotubes surface. The effect of applied electrical fields, deposition time and concentration of nanoparticulates on coatings morphology were investigated by scanning electron microscopy. It was found that combination of MWCNTs within TiO2 matrix eliminating micro cracks presented on TiO2 coating. Also, by increasing the deposition voltages, micro cracks were increased. SEM observation of the coatings revealed that TiO2/multi-walled carbon nanotubes coatings produced from optimized electric field was uniform and had good adhesive to the substrate.

  9. 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 .

  10. 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.

  11. 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

  12. Influence of surface treatment on preparing nanosized TiO2 supported on carbon nanotubes

    International Nuclear Information System (INIS)

    Wang Shuo; Ji Lijun; Wu Bin; Gong Qianming; Zhu Yuefeng; Liang Ji

    2008-01-01

    In this paper, nanosize titanium dioxide (TiO 2 ) deposited on pristine and acid treated carbon nanotubes (CNTs) were prepared by a modified sol-gel method. The nanoscale materials were extensively characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR) and Raman spectra. The results indicated that about 6.8 nm TiO 2 nanoparticles were successfully deposited on acid-treated CNTs surface homogeneously and densely, which was smaller than TiO 2 coated on pristine CNTs. The surface state of CNTs was a critical factor in obtaining a homogeneous distribution of nanoscale TiO 2 particles. Acid oxidization could etch the surface of CNTs and introduce functional groups, which were beneficial to controllable homogeneous deposition. The TiO 2 coated on acid-treated CNTs was used as photocatalyst for Reactive Brilliant Red X-3B dye degradation under UV irradiation, which showed higher efficiency than that of TiO 2 coated on pristine CNTs and commercial photocatalyst P25.

  13. Carbon coated anatase TiO2 mesocrystals enabling ultrastable and robust sodium storage

    Science.gov (United States)

    Zhang, Weifeng; Lan, Tongbin; Ding, Tianli; Wu, Nae-Lih; Wei, Mingdeng

    2017-08-01

    Nanoporous anatase TiO2 mesocrystals with tunable architectures and crystalline phases were successfully fabricated in the presence of the butyl oleate and oleylamine. Especially, the introduced surfactants served as a carbon source, bring a uniform carbon layer (about 2-8 nm) for heightening the electronic conductivity. The carbon coated TiO2 mesocrystals assembled from crystalline tiny subunits have more space sites for sodium-ion storage. When the material was applied as an electrode material in rechargeable sodium-ion batteries, it exhibited a superior capacity of about 90 mA h g-1 at 20 C (1 C = 168 mA g-1) and a highly reversible capacity for 5000 cycles, which is the longest cycle life reported for sodium storage in TiO2 electrodes.

  14. 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.

  15. Rational design of carbon and TiO2 assembly materials: covered or strewn, which is better for photocatalysis?

    Science.gov (United States)

    Cui, Guan-wei; Wang, Wei-liang; Ma, Ming-yue; Zhang, Ming; Xia, Xin-yuan; Han, Feng-yun; Shi, Xi-feng; Zhao, Ying-qiang; Dong, Yu-bin; Tang, Bo

    2013-07-21

    The rational design of carbonaceous hybrid nanostructures is very important for obtaining high photoactivity. TiO2 particles strewn with an optimal quantity of carbon nanodots have a much higher photoactivity than that of TiO2 covered with a carbon layer, showing the importance of carbon morphology in the photocatalysis of carbonaceous hybrid nanostructures.

  16. Double-wall carbon nanotubes doped with different Br2 doping levels: a resonance Raman study.

    Science.gov (United States)

    do Nascimento, Gustavo M; Hou, Taige; Kim, Yoong Ahm; Muramatsu, Hiroyuki; Hayashi, Takuya; Endo, Morinobu; Akuzawa, Noboru; Dresselhaus, Mildred S

    2008-12-01

    This report focuses on the effects of different Br2 doping levels on the radial breathing modes of "double-wall carbon nanotube (DWNT) buckypaper". The resonance Raman profile of the Br2 bands are shown for different DWNT configurations with different Br2 doping levels. Near the maximum intensity of the resonance Raman profile, mainly the Br2 molecules adsorbed on the DWNT surface contribute strongly to the observed omega(Br-Br) Raman signal.

  17. Separation of yttrium using carbon nanotube doped polymeric beads impregnated with D2EHPA

    International Nuclear Information System (INIS)

    Dasgupta, Kinshuk; Yadav, Kartikey K.; Singh, D.K.; Anitha, M.; Singh, H.

    2013-01-01

    Di-2-ethylhexyl phosphoric acid impregnated polyethersulfone based composite beads in combination with additives such as polyvinyl alcohol (PVA) and multiwalled carbon nanotube (MWCNT) has been prepared by non-solvent phase inversion method. The synthesized beads were characterized by scanning electron microscopy, thermogravimetry and infra-red spectroscopy. Effect of additives on bead morphology, solvent impregnation capacity, extractability and stability has been examined to compare their suitability for yttrium recovery from acidic medium. Microstructural investigation as well as experimental findings confirmed the role of additives in modifying the pore structures in beads, responsible for varied degree of yttrium extraction. Further the role of metal ion concentration in aqueous phase on its recovery by polymeric beads was also evaluated. Among the tested beads PES/D2EHPA/MWCNT/PVA beads were found to be superior for Y(Ill) extraction. (author)

  18. Carbon nanotubes doped with trivalent elements by using back - scattering Raman spectroscopy

    Directory of Open Access Journals (Sweden)

    S. A. Babanejad

    2008-12-01

    Full Text Available  In this paper by using DC arc discharge method and acetylene gas, as the carbon source, and nitrogen, as the carrier gas, canrbon nanotubes, CNTs, doped with trivalent element boron, B, have been produced. The deposited CNTs on the cathod electrod, which have structural doped properties to boron element, have been collected and after purification have been investigated by back-scattering Raman spectroscopy. The results reveal that the high frequency G mode component in CNTs doped with electron acceptor element, B, shift to higher wavenumbers. The low frequency G mode component which can appear at approximately 1540–1570 cm-1 wavenumber region, called BWF mode, is a sign of metallic CNT. In the synthesized doped CNTs due to the presence of boron dopant, D mode has sharp peaks and has relatively high intensity in the Raman spectra .

  19. Enriching the hydrogen storage capacity of carbon nanotube doped with polylithiated molecules

    Science.gov (United States)

    Panigrahi, P.; Naqvi, S. R.; Hankel, M.; Ahuja, R.; Hussain, T.

    2018-06-01

    In a quest to find optimum materials for efficient storage of clean energy, we have performed first principles calculations to study the structural and energy storage properties of one-dimensional carbon nanotubes (CNTs) functionalized with polylithiated molecules (PLMs). Van der Waals corrected calculations disclosed that various PLMs like CLi, CLi2, CLi3, OLi, OLi2, OLi3, bind strongly to CNTs even at high doping concentrations ensuring a uniform distribution of dopants without forming clusters. Bader charge analysis reveals that each Li in all the PLMs attains a partial positive charge and transform into Li+ cations. This situation allows multiple H2 molecules adsorbed with each Li+ through the polarization of incident H2 molecules via electrostatic and van der Waals type of interaction. With a maximum doping concentration, that is 3CLi2/3CLi3 and 3OLi2/3OLi3 a maximum of 36 H2 molecules could be adsorbed that corresponds to a reasonably high H2 storage capacity with the adsorption energies in the range of -0.33 to -0.15 eV/H2. This suits the ambient condition applications.

  20. 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)

  1. Flexible symmetric supercapacitors based on vertical TiO2 and carbon nanotubes

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    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.

  2. Photocatalytic degradation of an azo-dye on TiO2/activated carbon composite material.

    Science.gov (United States)

    Andriantsiferana, C; Mohamed, E F; Delmas, H

    2014-01-01

    A sequential adsorption/photocatalytic regeneration process to remove tartrazine, an azo-dye in aqueous solution, has been investigated. The aim ofthis work was to compare the effectiveness of an adsorbent/photocatalyst composite-TiO2 deposited onto activated carbon (AC) - and a simple mixture of powders of TiO2 and AC in same proportion. The composite was an innovative material as the photocatalyst, TiO2, was deposited on the porous surface ofa microporous-AC using metal-organic chemical vapour deposition in fluidized bed. The sequential process was composed of two-batch step cycles: every cycle alternated a step of adsorption and a step of photocatalytic oxidation under ultra-violet (365 nm), at 25 degreeC and atmospheric pressure. Both steps, adsorption and photocatalytic oxidation, have been investigated during four cycles. For both materials, the cumulated amounts adsorbed during four cycles corresponded to nearly twice the maximum adsorption capacities qmax proving the photocatalytic oxidation to regenerate the adsorbent. Concerning photocatalytic oxidation, the degree of mineralization was higher with the TiO2/AC composite: for each cycle, the value of the total organic carbon removal was 25% higher than that obtained with the mixture powder. These better photocatalytic performances involved better regeneration than higher adsorbed amounts for cycles 2, 3 and 4. Better performances with this promising material - TiO2 deposited onto AC - compared with TiO2 powder could be explained by the vicinity of photocatalytic and AC adsorption sites.

  3. 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

  4. 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

  5. Formation of Sol Gel Dried Droplets of Carbon Doped Titanium Dioxide (TiO2) at Low Temperature via Electrospraying

    Science.gov (United States)

    Halimi, S. U.; Hashib, S. Abd; Abu Bakar, N. F.; Ismail, S. N.; Nazli Naim, M.; Rahman, N. Abd; Krishnan, J.

    2018-05-01

    The high band gap energy of TiO2 and inconsistency in particles size has imposed a significant drawback on TiO2 applications. Dried droplets of carbon-doped TiO2 fine particles were produced by using electrospraying technique. The C-doped TiO2 particles were prepared by hydrolysis of titanium isopropoxide with the addition of carbon precursor followed by electrospraying the suspension in stable Taylor cone-jet mode. Coulomb fission of charged droplets from the electrospraying technique successfully transformed dispersed liquid C-doped TiO2 particles into solid. The deposited C-doped TiO2 droplets were collected on aluminium substrates placed at working distances of 10 to 20 cm from the tip of the electrospray needle. The collected C-doped TiO2 droplets were characterized by using FESEM, UV-Vis, FTIR and XRD. By increasing the working distance, the average droplets size of the deposited C-doped TiO2 was reduced from ±163.2 nm to ±147.56 nm. UV-Vis analysis showed a strong absorption in the visible-light region and about 93 nm red shift of the onset spectrum for C-doped TiO2. The red shift indicates an increase in photocatalytic efficiency by reducing the TiO2 band gap energy from 3.0 eV to 2.46 eV and shifting its activity to the visible-light region. FTIR analysis indicated the presence of Ti-C and C-O chemical bonding in the C-doped TiO2.

  6. TiO2-anatase modified by carbon as the photo catalyst under visible light

    International Nuclear Information System (INIS)

    Morawski, A.W.; Janus, M.; Tryba, B.; Kalucki, K.; Tryba, B.; Inagaki, M.

    2006-01-01

    The photo-catalytic oxidation of phenol in water under a visible light over anatase-type titanium dioxide (Tytanpol A11, Poland), modified by carbon deposited via n-hexane carbonization, was investigated. The catalysts, which had small (0-0.2 mass%) and high (0.69-0.85 mass%) contents of carbon showed a little lower catalytic photo-activity than pristine TiO 2 . However, the catalyst with high content of carbon (0.85 mass%) gave almost 14-times lower turbidity in the phenol solution after the photo-catalyst sedimentation. These two factors depend on the carbon content and have an influence on the 'practical efficiency' of the catalysts. The 'practical efficiency' of the catalyst under visible light, calculated from these two factors, was therefore 14-times higher for the catalyst containing 0.85 mass% carbon (whereas for UV radiation, it was found to be lower - 0.2 mass% -; this is the result of a previous work). The surface modification of the catalyst with 0.85% carbon seemed to be stable under visible light. The deposition of carbon on TiO 2 by carbonization of n-hexane was supposed to lead to obtain the catalyst, which could be easily used in a water-treatment system under visible light. (authors)

  7. Particle-size effect on the rate of TiO2 carbonizing

    International Nuclear Information System (INIS)

    Lekanova, T.L.; Ryabkov, Yu.I.; Sevbo, O.A.

    2003-01-01

    Dependence of recovery rate constant of titanium dioxide in TiO 2 -C system on the value of specific surface initial components at 1300 deg C was studied. It is shown that decrease in equivalent particle size of titanium dioxide and carbon particles in the range of 500-100 μm has a similar effect on increase in titanium dioxide recovery rate. Analysis of kinetic equations suggests diffusion character of titanium dioxide carbonizing at the values of initial components specific surface in excess of 100 m 2 /g [ru

  8. PHOTOCATALYTIC DECOMPOSITION OF GASEOUS TOLUENE BY TIO2 NANOPARTICLES COATED ON ACTIVATED CARBON

    Directory of Open Access Journals (Sweden)

    A. Rezaee ، Gh. H. Pourtaghi ، A. Khavanin ، R. Sarraf Mamoory ، M. T. Ghaneian ، H. Godini

    2008-10-01

    Full Text Available Volatile organic compounds are considered as a group of major environmental pollutants and toluene is recognized as one of the representatives. In this research, the photocatalytic activity for toluene removal was studied over TiO2 nanoparticles embeded on activated carbon. Laboratory-scale experiments were conducted in a fixed-bed reactor equipped with 4 w and 8 w UV lamps (peak wavelength at 365 nm to determine the oxidation rates of toluene. The photocatalyst was extensively characterized by means of X- ray diffraction and scan electronmicroscopy. Experiments were conducted under general laboratory temperature (25ºC±2 while the irradiation was provided by the UV lamps. The dependence of the reaction rate on light intensity as well as the deactivation of the catalyst were determined. The results indicated that the rate of the photocatalytic process increased with increasing the intensity of UV irradiation. Using the UV-A lamps, the decomposition rate of toluene was 98%. The stabilized photocatalyst presented remarkable stability (no deactivation and excellent repeatability. The catalyst could be regenerated by UV irradiation in the absence of gas phase. The control experiments confirmed that the photocatalytic effects of toluene onto the TiO2/activated carbon catalysts in the dark conditions were negligible. Reproducibility tests proved that the photocatalytic activity of the photocatalyst remains intact even after several experiments of new added toluene quantities. The study demonstrated that the TiO2/activated carbon catalyst may be a practical and promising way to degrade the toluene under ultraviolet irradiation.

  9. 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.

  10. Evaluating the Catalytic Effects of Carbon Materials on the Photocatalytic Reduction and Oxidation Reactions of TiO2

    International Nuclear Information System (INIS)

    Khan, Gulzar; Kim, Young Kwang; Choi, Sung Kyu; Han, Dong Suk; Abdelwahab, Ahmed; Park, Hyunwoong

    2013-01-01

    TiO 2 composites with seven different carbon materials (activated carbons, graphite, carbon fibers, single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene oxides, and reduced graphene oxides) that are virgin or treated with nitric acid are prepared through an evaporation method. The photocatalytic activities of the as-prepared samples are evaluated in terms of H 2 production from aqueous methanol solution (photo-catalytic reduction: PCR) and degradation of aqueous pollutants (phenol, methylene blue, and rhodamine B) (photocatalytic oxidation: PCO) under AM 1.5-light irradiation. Despite varying effects depending on the kinds of carbon materials and their surface treatment, composites typically show enhanced PCR activity with maximum 50 times higher H 2 production as compared to bare TiO 2 . Conversely, the carbon-induced synergy effects on PCO activities are insignificant for all three substrates. Colorimetric quantification of hydroxyl radicals supports the absence of carbon effects. However, platinum deposition on the binary composites displays the enhanced effect on both PCR and PCO reactions. These differing effects of carbon materials on PCR and PCO reactions of TiO 2 are discussed in terms of physicochemical properties of carbon materials, coupling states of TiO 2 /carbon composites, interfacial charge transfers. Various surface characterizations of composites (UV-Vis diffuse reflectance, SEM, FTIR, surface area, electrical conductivity, and photoluminescence) are performed to gain insight on their photocatalytic redox behaviors

  11. Amorphous TiO2 doped with carbon for visible light photodegradation of rhodamine B and 4-chlorophenol

    International Nuclear Information System (INIS)

    Shao, Penghui; Tian, Jiayu; Zhao, Zhiwei; Shi, Wenxin; Gao, Shanshan; Cui, Fuyi

    2015-01-01

    Graphical abstract: - Highlights: • Amorphous TiO 2 doped with carbon is prepared as a visible photocatalyst. • RhB and 4-chlorophenol are decomposed effectively by carbon-doped amorphous TiO 2 . • The mechanism for visible light photocatalysis is discussed detailedly. - Abstract: Visible light photocatalytic activity of amorphous TiO 2 doped with carbon is prepared by a facile sol-gel route for the first time. The most active sample with mesostructure of amorphous phase, high surface area (273 m 2 g −1 ) and large pore volume (0.33 cm 3 g −1 ) is identified by X-ray diffractometer, Raman spectrometer, transmission electron microscope and N 2 adsorption–desorption isotherms. In addition, the most active sample is characterized by Fourier transform-infrared spectrometer, X-ray photoelectron spectrometer, UV–vis diffuse reflectance spectrometer and luminescence spectrometer. The results show that the most active sample with oxygenic groups has a narrower bandgap and lower recombination of electron–hole, due to the carbon doping and phase of amorphous. Effective photodegradation capability and stability of rhodamine B and colorless 4-chlorophenol are verified by photocatalytic tests under visible light irradiation. A possible mechanism of amorphous TiO 2 doped with carbon for visible light photocatalysis is proposed. The findings of this paper will provide new insights to design visible light-induced photocatalyst based on amorphous TiO 2 for organic removal

  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. Photocatalytic properties of nano-structured TiO2-carbon films obtained by means of electrophoretic deposition

    International Nuclear Information System (INIS)

    Peralta-Hernandez, J.M.; Manriquez, J.; Meas-Vong, Y.; Rodriguez, Francisco J.; Chapman, Thomas W.; Maldonado, Manuel I.; Godinez, Luis A.

    2007-01-01

    Recent studies have shown that the light-absorption and photocatalytic efficiencies of TiO 2 can be improved by coupling TiO 2 nano-particles with nonmetallic dopants, such as carbon. In this paper, we describe the electrophoretic preparation of a novel TiO 2 -carbon nano-composite photocatalyst on a glass indium thin oxide (ITO) substrate. The objective is to take better advantage of the (e - /h + ) pair generated by photoexcitation of semiconducting TiO 2 particles. The transfer of electrons (e - ) into adjacent carbon nano-particles promotes reduction of oxygen to produce hydrogen peroxide (H 2 O 2 ) which, in the presence of iron ions, can subsequently form hydroxyl radicals ( · OH) via the Fenton reaction. At the same time, · OH is formed from water by the (h + ) holes in the TiO 2 . Thus, the · OH oxidant is produced by two routes. The efficiency of this photolytic-Fenton process was tested with a model organic compound, Orange-II (OG-II) azo dye, which is employed in the textile industry

  14. Influence of Different Defects in Vertically Aligned Carbon Nanotubes on TiO2 Nanoparticle Formation through Atomic Layer Deposition.

    Science.gov (United States)

    Acauan, Luiz; Dias, Anna C; Pereira, Marcelo B; Horowitz, Flavio; Bergmann, Carlos P

    2016-06-29

    The chemical inertness of carbon nanotubes (CNT) requires some degree of "defect engineering" for controlled deposition of metal oxides through atomic layer deposition (ALD). The type, quantity, and distribution of such defects rules the deposition rate and defines the growth behavior. In this work, we employed ALD to grow titanium oxide (TiO2) on vertically aligned carbon nanotubes (VACNT). The effects of nitrogen doping and oxygen plasma pretreatment of the CNT on the morphology and total amount of TiO2 were systematically studied using transmission electron microscopy, Raman spectroscopy, and thermogravimetric analysis. The induced chemical changes for each functionalization route were identified by X-ray photoelectron and Raman spectroscopies. The TiO2 mass fraction deposited with the same number of cycles for the pristine CNT, nitrogen-doped CNT, and plasma-treated CNT were 8, 47, and 80%, respectively. We demonstrate that TiO2 nucleation is dependent mainly on surface incorporation of heteroatoms and their distribution rather than structural defects that govern the growth behavior. Therefore, selecting the best way to functionalize CNT will allow us to tailor TiO2 distribution and hence fabricate complex heterostructures.

  15. Carbon nanotube TiO2 hybrid films for detecting traces of O2

    Science.gov (United States)

    Llobet, E.; Espinosa, E. H.; Sotter, E.; Ionescu, R.; Vilanova, X.; Torres, J.; Felten, A.; Pireaux, J. J.; Ke, X.; Van Tendeloo, G.; Renaux, F.; Paint, Y.; Hecq, M.; Bittencourt, C.

    2008-09-01

    Hybrid titania films have been prepared using an adapted sol-gel method for obtaining well-dispersed hydrogen plasma-treated multiwall carbon nanotubes in either pure titania or Nb-doped titania. The drop-coating method has been used to fabricate resistive oxygen sensors based on titania or on titania and carbon nanotube hybrids. Morphology and composition studies have revealed that the dispersion of low amounts of carbon nanotubes within the titania matrix does not significantly alter its crystallization behaviour. The gas sensitivity studies performed on the different samples have shown that the hybrid layers based on titania and carbon nanotubes possess an unprecedented responsiveness towards oxygen (i.e. more than four times higher than that shown by optimized Nb-doped TiO2 films). Furthermore, hybrid sensors containing carbon nanotubes respond at significantly lower operating temperatures than their non-hybrid counterparts. These new hybrid sensors show a strong potential for monitoring traces of oxygen (i.e. beverage industry.

  16. 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

  17. TiO2-coated mesoporous carbon: conventional vs. microwave-annealing process.

    Science.gov (United States)

    Coromelci-Pastravanu, Cristina; Ignat, Maria; Popovici, Evelini; Harabagiu, Valeria

    2014-08-15

    The study of coating mesoporous carbon materials with titanium oxide nanoparticles is now becoming a promising and challenging area of research. To optimize the use of carbon materials in various applications, it is necessary to attach functional groups or other nanostructures to their surface. The combination of the distinctive properties of mesoporous carbon materials and titanium oxide is expected to be applied in field emission displays, nanoelectronic devices, novel catalysts, and polymer or ceramic reinforcement. But, their synthesis is still largely based on conventional techniques, such as wet impregnation followed by chemical reduction of the metal nanoparticle precursors, which takes time and money. The thermal heating based techniques are time consuming and often lack control of particle size and morphology. Hence, since there is a growing interest in microwave technology, an alternative way of power input into chemical reactions through dielectric heating is the use of microwaves. This work is focused on the advantages of microwave-assisted synthesis of TiO2-coated mesoporous carbon over conventional thermal heating method. The reviewed studies showed that the microwave-assisted synthesis of such composites allows processes to be completed within a shorter reaction time allowing the nanoparticles formation with superior properties than that obtained by conventional method. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Vertically aligned TiO2 nanorods-woven carbon fiber for reinforcement of both mechanical and anti-wear properties in resin composite

    Science.gov (United States)

    Fei, Jie; Zhang, Chao; Luo, Dan; Cui, Yali; Li, Hejun; Lu, Zhaoqing; Huang, Jianfeng

    2018-03-01

    A series of TiO2 nanorods were successfully grown on woven carbon fiber by hydrothermal method to reinforce the resin composite. The TiO2 nanorods improved the mechanical interlocking among woven carbon fibers and resin matrix, resulting in better fibers/resin interfacial bonding. Compared with desized-woven carbon fiber, the uniform TiO2 nanorods array resulted in an improvement of 84.3% and 73.9% in the tensile and flexural strength of the composite. However, the disorderly TiO2 nanorods on woven carbon fiber leaded to an insignificant promotion of the mechanical strength. The enhanced performance of well-proportioned TiO2 nanorods-woven carbon fiber was also reflected in the nearly 56% decrease of wear rate, comparing to traditional woven carbon fiber reinforced composite.

  19. 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.

  20. Removal of Trichloroethylene by Activated Carbon in the Presence and Absence of TiO2 Nanoparticles

    Science.gov (United States)

    Nanoparticles (NPs) are emerging as a new type of contaminant in water and wastewater. The fate of titanium dioxide nanoparticles (TiO2NPs) in a granular activated carbon (GAC) adsorber and their impact on the removal of trichloroethylene (TCE) by GAC was investigated...

  1. 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.

  2. Substitutional Carbon-Modified Anatase TiO2 Decahedral Plates Directly Derived from Titanium Oxalate Crystals via Topotactic Transition.

    Science.gov (United States)

    Niu, Ping; Wu, Tingting; Wen, Lei; Tan, Jun; Yang, Yongqiang; Zheng, Shijian; Liang, Yan; Li, Feng; Irvine, John Ts; Liu, Gang; Ma, Xiuliang; Cheng, Hui-Ming

    2018-03-30

    Changing the composition and/or structure of some metal oxides at the atomic level can significantly improve their performance in different applications. Although many strategies have been developed, the introduction of heteroatoms, particularly anions to the internal part of metal oxide particles, is still not adequate. Here, an effective strategy is demonstrated for directly preparing polycrystalline decahedral plates of substitutional carbon-doped anatase TiO 2 from titanium (IV) oxalate by a thermally induced topotactic transition in an inert atmosphere. Because of the carbon concentration gradient introduced in side of the plates, the carbon-doped TiO 2 (TiO 2- x C x ) shows an increased visible light absorption and a two orders of magnitude higher electrical conductivity than pure TiO 2 . Consequently, it can be used as a photocatalyst and an active material for lithium storage and shows much superior activity in generating hydroxyl radicals under visible light and greatly increased electrical-specific capacity at high charge-discharge rates. The strategy developed could also be applicable to the atomic-scale modification of other metal oxides. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Fabrication of TiO2/Carbon Photocatalyst using Submerged DC Arc Discharged in Ethanol/Acetic Acid Medium

    Science.gov (United States)

    Saraswati, T. E.; Nandika, A. O.; Andhika, I. F.; Patiha; Purnawan, C.; Wahyuningsih, S.; Rahardjo, S. B.

    2017-05-01

    This study aimed to fabricate a modified photocatalyst of TiO2/C to enhance its performance. The fabrication was achieved using the submerged direct current (DC) arc-discharge method employing two graphite electrodes, one of which was filled with a mixture of carbon powder, TiO2, and binder, in ethanol with acetic acid added in various concentrations. The arc-discharge method was conducted by flowing a current of 10-20 A (~20 V). X-ray diffraction (XRD) patterns showed significant placements of the main peak characteristics of TiO2, C graphite, and titanium carbide. The surface analysis using Fourier transform infrared spectroscopy (FTIR) revealed that fabricated TiO2/C nanoparticles had stretching vibrations of Ti-O, C-H, C═O, C-O, O-H and C═C in the regions of 450-550 cm-1, 2900-2880 cm-1, 1690-1760 cm-1, 1050-1300 cm-1, 3400-3700 cm-1 and ~1600 cm-1, respectively. In addition, the study investigated the photocatalysts of unmodified and modified TiO2/C for photodegradation of methylene blue (MB) dye solution under mercury lamp irradiation. The effectiveness of the degradation was defined by the decrease in 60-minute absorbance under a UV-Vis spectrophotometer. Modified TiO2/C proved to be significantly more efficient in reducing dye concentrations, reaching ~70%. It indicated that the oxygen-containing functional groups have been successfully attached to the surface of the nanoparticles and played a role in enhancing photocatalytic activity.

  4. 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.

  5. 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

  6. HOMO-LUMO analysis of multi walled carbon nanotubes doped Tetrafluoro Phthalate crystals for nonlinear optical applications

    Science.gov (United States)

    Latha, B.; Kumaresan, P.; Nithiyanantham, S.; Sampathkumar, K.

    2018-01-01

    The MWCNTs doped Tetrafluoro Phthalate (C6H2F4O4) precious stones are constantly having higher transmission rate contrasted with immaculate Tetrafluoro Phthalate crystal. The dependability of Tetrafluoro Phthalate crystal was enhanced by doping MWCNTs.The basic, synthetic, optical, mechanical and non-direct optical properties of the doped precious crystals were dissected with the portrayal concentrates, for example, powder XRD, FT-IR, UV-Visible, Hardness and SHG estimations individually. The dopants are relied upon to substitute the carbon iotas in the Tetrafluoro Phthalate grid because of their change of valency and in addition vicinity of ionic sweep. The strength and charge delocalization of the particle were additionally concentrated on by characteristic security orbital (NBO) examination. The HOMO-LUMO energies depict the charge exchange happens inside the atom. Atomic electrostatic potential has been dissected. The SHG productivity of the immaculate and colors doped TFP crystals were additionally contemplated utilizing Nd:YAG Q-exchanged laser.

  7. Synergy between surface adsorption and photocatalysis during degradation of humic acid on TiO2/activated carbon composites

    International Nuclear Information System (INIS)

    Xue Gang; Liu Huanhuan; Chen Quanyuan; Hills, Colin; Tyrer, Mark; Innocent, Francis

    2011-01-01

    A photocatalyst comprising nano-sized TiO 2 particles on granular activated carbon (GAC) was prepared by a sol-dipping-gel process. The TiO 2 /GAC composite was characterized by scanning electron microscopy (SEM), X-ray diffractiometry (XRD) and nitrogen sorptometry, and its photocatalytic activity was studied through the degradation of humic acid (HA) in a quartz glass reactor. The factors influencing photocatalysis were investigated and the GAC was found to be an ideal substrate for nano-sized TiO 2 immobilization. A 99.5% removal efficiency for HA from solution was achieved at an initial concentration of 15 mg/L in a period of 3 h. It was found that degradation of HA on the TiO 2 /GAC composite was facilitated by the synergistic relationship between surface adsorption characteristics and photocatalytic potential. The fitting of experimental results with the Langmuir-Hinshelwood (L-H) model showed that the reaction rate constant and the adsorption constant values were 0.1124 mg/(L min) and 0.3402 L/mg. The latter is 1.7 times of the calculated value by fitting the adsorption equilibrium data into the Langmuir equation.

  8. Theoretical Investigation on Single-Wall Carbon Nanotubes Doped with Nitrogen, Pyridine-Like Nitrogen Defects, and Transition Metal Atoms

    Directory of Open Access Journals (Sweden)

    Michael Mananghaya

    2012-01-01

    Full Text Available This study addresses the inherent difficulty in synthesizing single-walled carbon nanotubes (SWCNTs with uniform chirality and well-defined electronic properties through the introduction of dopants, topological defects, and intercalation of metals. Depending on the desired application, one can modify the electronic and magnetic properties of SWCNTs through an appropriate introduction of imperfections. This scheme broadens the application areas of SWCNTs. Under this motivation, we present our ongoing investigations of the following models: (i (10, 0 and (5, 5 SWCNT doped with nitrogen (CNxNT, (ii (10, 0 and (5, 5 SWCNT with pyridine-like defects (3NV-CNxNT, (iii (10, 0 SWCNT with porphyrine-like defects (4ND-CNxNT. Models (ii and (iii were chemically functionalized with 14 transition metals (TMs: Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Pd, Ag, Pt and Au. Using the spin-unrestricted density functional theory (DFT, stable configurations, deformations, formation and binding energies, the effects of the doping concentration of nitrogen, pyridine-like and porphyrine-like defects on the electronic properties were all examined. Results reveal that the electronic properties of SWCNTs show strong dependence on the concentration and configuration of nitrogen impurities, its defects, and the TMs adsorbed.

  9. Functionalized carbon nanotube doping of P3HT:PCBM photovoltaic devices for enhancing short circuit current and efficiency

    Directory of Open Access Journals (Sweden)

    Rohit Bhatia

    2017-03-01

    Full Text Available We have successfully functionalized multiwalled carbon nanotubes (MWCNTs using nitrene approach employing the two aryl azides as a precursor for nitrene generation. The dispersion of functionalized MWCNTs has been enhanced in various organic solvents. These functionalized MWCNTs have been successfully doped in various concentrations in the bulk heterojunction (BHJ organic photovoltaic (OPV cells with a poly (3-hexyl thiophene (P3HT and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM photoactive blended layer. The incorporation of MWCNTs with aryl functional groups, in active the layer, results in enhanced performance with respect to a reference cell. The maximum power conversion efficiency of 1.86% is achieved with adduct I while in the case of adduct II it gets double to 2.0% in comparison with a reference cell. This improvement in the device performance is attributed to enhanced exciton dissociation and improved charge transport properties due to the formation of a nanotube percolation network in the photoactive composite layer.

  10. Application of carbon-coated TiO2 for decomposition of methylene blue in a photocatalytic membrane reactor

    International Nuclear Information System (INIS)

    Mozia, Sylwia; Toyoda, Masahiro; Inagaki, Michio; Tryba, Beata; Morawski, Antoni W.

    2007-01-01

    An application of carbon-coated TiO 2 for decomposition of methylene blue (MB) in a photocatalytic membrane reactor (PMR), coupling photocatalysis and direct contact membrane distillation (DCMD) was investigated. Moreover, photodegradation of a model pollutant in a batch reactor without membrane distillation (MD) was also examined. Carbon-modified TiO 2 catalysts containing different amount of carbon and commercially available TiO 2 (ST-01) were used in this study. The carbon-coated catalyst prepared from a mixture of ST-01 and polyvinyl alcohol in the mass ratio of 70/30 was the most effective in degradation of MB from all of the photocatalysts applied. Photodecomposition of MB on the recovered photocatalysts was lower than on the fresh ones. The photodegradation of MB in the PMR was slower than in the batch reactor, what probably resulted from shorter time of exposure of the catalyst particles to UV irradiation. The MD process could be successfully applied for separation of photocatalyst and by-products from the feed solution

  11. 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.

  12. Synthesis and superior anode performances of TiO2-carbon-rGO composites in lithium-ion batteries.

    Science.gov (United States)

    Ren, Yameng; Zhang, Juan; Liu, Yanyan; Li, Hongbian; Wei, Huijuan; Li, Baojun; Wang, Xiangyu

    2012-09-26

    In this article, TiO(2)-Carbon-rGO (GCT) three-component composite material has been constructed by anchoring TiO(2) nanoparticles (NPs) encapsulated in carbon shells onto reduced graphene oxide (rGO) sheets. The structure of GCT was characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), N(2) adsorption-desorption isotherms, and transmission electron microscopy (TEM). This material shows a superior retention as the anode materials in lithium ion battery with a specific discharge capacity of 188 mA h g(-1) in the initial cycle and 158 mA h g(-1) after 100 cycles.

  13. TiO2/carbon nanotube hybrid nanostructures: Solvothermal synthesis and their visible light photocatalytic activity

    International Nuclear Information System (INIS)

    Tian Lihong; Ye Liqun; Deng Kejian; Zan Ling

    2011-01-01

    MWCNT/TiO 2 hybrid nanostructures were prepared via solvothermal synthesis and sol-gel method with benzyl alcohol as a surfactant. As-prepared hybrid materials were characterized by X-ray diffraction, transmission electron microscopy, UV-vis diffuse reflectance spectra and X-ray photoelectron spectroscopy. The results showed that MWCNTs were uniformly decorated with anatase nanocrystals in solvothermal condition, but MWCNTs were embedded in a majority of TiO 2 nanoparticles by sol-gel method. When the weight ratio of MWCNTs to TiO 2 was 20%, MWCNT/TiO 2 hybrid nanostructures prepared by solvothermal synthesis exhibited higher visible-light-driven photocatalytic activity than that prepared by sol-gel method. Post-annealing of MWCNT/TiO 2 nanostructures at 400 deg. C resulted in the formation of the carbonaceous Ti-C bonds on the interface between TiO 2 and MWCNTs, which enhanced the photoabsorbance of the hybrid materials in the visible light region and improved the visible-light degradation efficiency of methylene blue. - Graphical abstract: MWCNT/TiO 2 nanostructures have been prepared by solvothermal method, which exhibited higher visible-light-driven photocatalytic activity than that prepared by sol-gel method. The carbonaceous Ti-C bonds on the interface between TiO 2 and MWCNTs enhanced the photoabsorbance of the hybrid materials in the visible light region. Highlights: → Anatase TiO 2 nanoparticles were anchored on CNTs surface uniformly via solvothermal method → The morphology facilitated the electron transfer between CNTs and TiO 2 → Ti-C bonds extended the absorption of MWCNT/TiO 2 to the whole visible light region. → The hybrid nanostructures showed enhanced visible-light induced photocatalytic activity.

  14. Multiwalled carbon nanotubes decorated with nitrogen, palladium co-doped TiO2 (MWCNT/N, Pd co-doped TiO2) for visible light photocatalytic degradation of Eosin Yellow in water

    Science.gov (United States)

    Kuvarega, Alex T.; Krause, Rui W. M.; Mamba, Bhekie B.

    2012-03-01

    Multiwalled carbon nanotube (MWCNT/N), Pd co-doped TiO2 nanocomposites were prepared by calcining the hydrolysis products of the reaction of titanium isopropoxide, Ti(OC3H7)4 containing multiwalled carbon nanotubes with aqueous ammonia. The prepared samples were characterised by Fourier transform infrared spectroscopy, Raman spectroscopy, thermogravimetric analysis, diffuse reflectance UV-Vis spectrophotometry (DRUV-Vis), XRD, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). DRUV-Vis analysis confirmed the red shift in the absorption edge at lower MWCNT percentages. SEM and TEM images showed the complete coverage of the MWCNTs with clusters of anatase TiO2 at low MWCNT percentages. Higher MWCNT levels led to their aggregation and consequently poor coverage by N, Pd co-doped TiO2. The photocatalytic activities of the nanocomposites were monitored by photodegradation of Eosin Yellow under simulated solar and visible light irradiation (λ > 450 nm). Irradiation with simulated solar radiation gave higher dye-degradation rates compared to visible radiation. The optimum MWCNT weight percentage in the composites was found to be 0.5. High degradation-rate constants of 3.42 × 10-2 and 5.18 × 10-3 min-1 were realised for the 0.5% MWCNT/N, Pd co-doped TiO2 composite, using simulated solar light and visible light, respectively.

  15. 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.

  16. Photocatalytic degradation of clofibric acid, carbamazepine and iomeprol using conglomerated TiO2 and activated carbon in aqueous suspension.

    Science.gov (United States)

    Ziegmann, Markus; Frimmel, Fritz H

    2010-01-01

    The combination of powdered activated carbon (PAC) and TiO(2) has been tested for synergistic/antagonistic effects in the photocatalytic degradation of carbamazepine, clofibric acid and iomeprol. Synergistic effects are thought to be caused by rapid adsorption on the PAC surface followed by diffusion to the TiO(2) surface and photocatalytic degradation. The Freundlich constant K(F) was used for comparing the sorption properties of the three substances and it was found that K(F) for clofibric acid was 3 times lower than for carbamazepine and iomeprol, regardless of the kind of PAC used. A PAC with a distinct tendency to form conglomerates was selected so that a high percentage of the PAC surface was in direct proximity to the TiO(2) surface. The photocatalytic degradation of the pharmaceutically active compounds studied followed pseudo-first order kinetics. Synergistic effects only occurred for clofibric acid (factor 1.5) and an inverse relationship between adsorption affinity and synergistic effects was found. High affinity of the target substances to the PAC surface seemed to be counterproductive for the photocatalytic degradation.

  17. Visible-Light Upconversion Carbon Quantum Dots Decorated TiO2 for the Photodegradation of Flowing Gaseous Acetaldehyde

    Science.gov (United States)

    Hu, Yidan; Xie, Xiaofeng; Wang, Xiao; Wang, Yan; Zeng, Yi; Pui, David Y. H.; Sun, Jing

    2018-05-01

    Carbon-modified photocatalyst has attracted extensive attentions in the field of gaseous pollutant removal, mainly due to the improved adsorption properties and electronic transport of carbon matrix, such as carbon nanotubes, graphene, and fullerene, etc. In this work, carbon quantum dots (CQDs) were employed to enhance the photocatalytic performance of TiO2-based composites for flowing gaseous acetaldehyde removal. Besides the aforementioned advantages of carbon materials, the unique up-converted photoluminescence property of CQDs is capable of extending the optical absorption to visible-light range. Moreover, the electron spin resonance (ESR) results firstly verified a stable existence of Ti3+ defect in the CQDs/TiO2 composite, which is possibly induced by the electron migration from CQDs to TiO2. And the formed Ti3+ donor energy level in the band gap could further help with the visible-light harvesting. During the photodegradation experiments, with two-hour continuous flowing gaseous acetaldehyde injection (500 ppm, 20 sccm), the CQDs/TiO2 composite remained 99% removal efficiency under fluorescent lamp irradiation (λ > 380 nm). The optimized CQDs content was obtained as 3 wt%, and the underlying mechanism was further analyzed by temperature programmed desorption (TPD) methods. This work will push forward the air purification researches by providing new insights of CQDs sensitized photocatalyst.

  18. Synthesis, characterization, and performance evaluation of multilayered photoanodes by introducing mesoporous carbon and TiO2 for humic acid adsorption

    Science.gov (United States)

    Hosseini, Soraya; Jahangirian, Hossein; Webster, Thomas J; Soltani, Salman Masoudi; Aroua, Mohamed Kheireddine

    2016-01-01

    Nanostructured photoanodes were prepared via a novel combination of titanium dioxide (TiO2) nanoparticles and mesoporous carbon (C). Four different photoanodes were synthesized by sol–gel spin coating onto a glassy substrate of fluorine-doped tin oxide. The photocatalytic activities of TiO2, TiO2/C/TiO2, TiO2/C/C/TiO2, and TiO2/C/TiO2/C/TiO2 photoanodes were evaluated by exposing the synthesized photoanodes to UV–visible light. The photocurrent density observed in these photoanodes confirmed that an additional layer of mesoporous carbon could successfully increase the photocurrent density. The highest photocurrent density of ~1.022 mA cm−2 at 1 V/saturated calomel electrode was achieved with TiO2/C/C/TiO2 under an illumination intensity of 100 mW cm−2 from a solar simulator. The highest value of surface roughness was measured for a TiO2/C/C/TiO2 combination owing to the presence of two continuous layers of mesoporous carbon. The resulting films had a thickness ranging from 1.605 µm to 5.165 µm after the calcination process. The presence of double-layer mesoporous carbon resulted in a 20% increase in the photocurrent density compared with the TiO2/C/TiO2 combination when only a single mesoporous carbon layer was employed. The improved performance of these photoanodes can be attributed to the enhanced porosity and increased void space due to the presence of mesoporous carbon. For the first time, it has been demonstrated here that the photoelectrochemical performance of TiO2 can be improved by integrating several layers of mesoporous carbon. Comparison of the rate of removal of humic acid by the prepared photoanodes showed that the highest performance from TiO2/C/C/TiO2 was due to the highest photocurrent density generated. Therefore, this study showed that optimizing the sequence of mesoporous carbon layers can be a viable and inexpensive method for enhanced humic acid removal. PMID:27574426

  19. Preparation and Characterization of Pd Modified TiO2 Nanofiber Catalyst for Carbon–Carbon Coupling Heck Reaction

    Directory of Open Access Journals (Sweden)

    Leah O. Nyangasi

    2017-01-01

    Full Text Available TiO2 fibers were prepared through electrospinning of poly methyl methacrylate (PMMA and titanium isopropoxide (TIP solution followed by calcination of fibers in air at 500°C. Cetyltrimethylammonium bromide (CTAB protected palladium nanoparticles (Pd NPs prepared through reduction method were successfully adsorbed on the TiO2 nanofibers (NF. Combined studies of X-ray diffraction (XRD, scanning electron microscope (SEM, and transmission electron microscope (TEM indicated that the synthesized Pd/TiO2 had anatase. BET indicated that the synthesized TiO2 and Pd/TiO2 had a surface area of 53.4 and 43.4 m2/g, respectively. The activity and selectivity of 1 mol% Pd/TiO2 in the Heck reaction have been investigated towards the Mizoroki-Heck carbon–carbon cross-coupling of bromobenzene (ArBr and styrene. Temperature, time, solvent, and base were optimized and catalyst was recycled thrice. 1H NMR and 13C NMR indicated that stilbene, a known compound from literature, was obtained in various Heck reactions at temperatures between 100°C and 140°C but the recyclability was limited due to some palladium leaching and catalyst poisoning which probably arose from some residual carbon from the polymer. The catalyst was found to be highly active under air atmosphere with reaction temperatures up to 140°C. Optimized reaction condition resulted in 89.7% conversions with a TON of 1993.4 and TOF value of 332.2 hr−1.

  20. 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 TiO 2 /ASS (TiO 2 nanoparticle coated sewage sludge-based activated carbon) was synthesized by the sol-gel method. The changes in surface properties of the TiO 2 /ASS nanocomposite were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and X-ray fluorescence. The prepared TiO 2 /ASS nanocomposite was applied for simultaneous removal of methyl orange dye (MO) and Cd 2+ from bi-pollutant solution. The factors influencing photocatalysis (TiO 2  : 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 Cd 2+ from bi-pollutant solution was achieved with TiO 2 /ASS at a ratio (1 : 2). The obtained results revealed that degradation of MO dye on the TiO 2 /ASS nanocomposite was facilitated by surface adsorption and photocatalytic processes. The coupled photocatalysis and adsorption shown by TiO 2 /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 TiO 2 /ASS (1 : 2) nanocomposite at optimum pH value 7 were 74.14 and 94.28%, respectively, while for Cd 2+ it was more than 90%. The experimental results fitted well with the second-order kinetic reaction.

  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. Synergistic effect of single-electron-trapped oxygen vacancies and carbon species on the visible light photocatalytic activity of carbon-modified TiO2

    International Nuclear Information System (INIS)

    Wang, Xiaodong; Xue, Xiaoxiao; Liu, Xiaogang; Xing, Xing; Li, Qiuye; Yang, Jianjun

    2015-01-01

    Carbon-modified TiO 2 (CT) nanoparticles were prepared via a two-step method of heat treatment without the resorcinol-formaldehyde (RF) polymer. As-prepared CT nanoparticles were characterized by means of X-ray diffraction (XRD), UV–Vis diffuse reflectance spectroscopy (UV–Vis/DRS), transmission electron microscopy (TEM), N 2 adsorption–desorption isotherms, thermal analysis (TA), electron spin resonance (ESR), and X-ray photoelectron spectroscopy (XPS). The visible light photocatalytic activities were evaluated on the basis of the degradation of methyl orange (MO). The synergistic effect of single-electron-trapped oxygen vacancies (SETOVs) and the carbon species on the visible light photocatalytic activities of the CT nanoparticles were discussed. It was found that the crystalline phase, the morphology, and particle size of the CT nanoparticles depended on the second heat-treatment temperature instead of the first heat-treatment temperature. The visible light photocatalytic activities were attributed to the synergistic effect of SETOVs and the carbon species, and also depended on the specific surface area of the photocatalysts. - Highlights: • Carbon-modified TiO 2 particles have been prepared without RF polymer. • The visible light photocatalytic activities of the particles have been evaluated. • The band gap energy structure of the carbon-modified TiO 2 has been proposed. • Synergistic effect of SETOVs and carbon species has been discussed. • The activities also depend on the specific surface area of the catalysts

  3. Solar cells with PbS quantum dot sensitized TiO2-multiwalled carbon nanotube composites, sulfide-titania gel and tin sulfide coated C-fabric.

    Science.gov (United States)

    Kokal, Ramesh K; Deepa, Melepurath; Kalluri, Ankarao; Singh, Shrishti; Macwan, Isaac; Patra, Prabir K; Gilarde, Jeff

    2017-10-04

    Novel approaches to boost quantum dot solar cell (QDSC) efficiencies are in demand. Herein, three strategies are used: (i) a hydrothermally synthesized TiO 2 -multiwalled carbon nanotube (MWCNT) composite instead of conventional TiO 2 , (ii) a counter electrode (CE) that has not been applied to QDSCs until now, namely, tin sulfide (SnS) nanoparticles (NPs) coated over a conductive carbon (C)-fabric, and (iii) a quasi-solid-state gel electrolyte composed of S 2- , an inert polymer and TiO 2 nanoparticles as opposed to a polysulfide solution based hole transport layer. MWCNTs by virtue of their high electrical conductivity and suitably positioned Fermi level (below the conduction bands of TiO 2 and PbS) allow fast photogenerated electron injection into the external circuit, and this is confirmed by a higher efficiency of 6.3% achieved for a TiO 2 -MWCNT/PbS/ZnS based (champion) cell, compared to the corresponding TiO 2 /PbS/ZnS based cell (4.45%). Nanoscale current map analysis of TiO 2 and TiO 2 -MWCNTs reveals the presence of narrowly spaced highly conducting domains in the latter, which equips it with an average current carrying capability greater by a few orders of magnitude. Electron transport and recombination resistances are lower and higher respectively for the TiO 2 -MWCNT/PbS/ZnS cell relative to the TiO 2 /PbS/ZnS cell, thus leading to a high performance cell. The efficacy of SnS/C-fabric as a CE is confirmed from the higher efficiency achieved in cells with this CE compared to the C-fabric based cells. Lower charge transfer and diffusional resistances, slower photovoltage decay, high electrical conductance and lower redox potential impart high catalytic activity to the SnS/C-fabric assembly for sulfide reduction and thus endow the TiO 2 -MWCNT/PbS/ZnS cell with a high open circuit voltage (0.9 V) and a large short circuit current density (∼20 mA cm -2 ). This study attempts to unravel how simple strategies can amplify QDSC performances.

  4. Dye-sensitized solar cells with vertically aligned TiO2 nanowire arrays grown on carbon fibers.

    Science.gov (United States)

    Cai, Xin; Wu, Hongwei; Hou, Shaocong; Peng, Ming; Yu, Xiao; Zou, Dechun

    2014-02-01

    One-dimensional semiconductor TiO2 nanowires (TNWs) have received widespread attention from solar cell and related optoelectronics scientists. The controllable synthesis of ordered TNW arrays on arbitrary substrates would benefit both fundamental research and practical applications. Herein, vertically aligned TNW arrays in situ grown on carbon fiber (CF) substrates through a facile, controllable, and seed-assisted thermal process is presented. Also, hierarchical TiO2 -nanoparticle/TNW arrays were prepared that favor both the dye loading and depressed charge recombination of the CF/TNW photoanode. An impressive conversion efficiency of 2.48 % (under air mass 1.5 global illumination) and an apparent efficiency of 4.18 % (with a diffuse board) due to the 3D light harvesting of the wire solar cell were achieved. Moreover, efficient and inexpensive wire solar cells made from all-CF electrodes and completely flexible CF-based wire solar cells were demonstrated, taking into account actual application requirements. This work may provide an intriguing avenue for the pursuit of lightweight, cost-effective, and high-performance flexible/wearable solar cells. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Enhanced performance of dye-sensitized solar cells with layered structure graphitic carbon nitride and reduced graphene oxide modified TiO2 photoanodes

    Science.gov (United States)

    Lv, Huiru; Hu, Haihua; Cui, Can; Lin, Ping; Wang, Peng; Wang, Hao; Xu, Lingbo; Pan, Jiaqi; Li, Chaorong

    2017-11-01

    TiO2/reduced graphene oxide (TiO2/rGO) composite has been widely exploited as the photoanode material for high efficient dye-sensitized solar cells (DSSCs). However, the power conversion efficiency (PCE) is limited due to the charge recombination between the rGO and electrolyte. In this paper, we incorporate 5.5 wt% layered structure graphitic carbon nitride (g-C3N4) and 0.25 wt% rGO into TiO2 nanoparticle (NP) film to form a triple-component TiO2/rGO/g-C3N4 (TGC) photoanode for DSSCs. The TGC photoanode significantly increased the dye absorption and thus to improve the light harvesting efficiency. Furthermore, the electrochemical impedance spectroscopy (EIS) analysis of the DSSCs based on TGC photoanode demonstrates that the incorporation of the rGO and g-C3N4 into TiO2 effectively accelerates the electron transfer and reduces the charge recombination. As a result, the DSSCs based on TGC film show PCE of 5.83%, enhanced by 50.1% compared with that of pure TiO2 photoanodes. This result strongly suggests a facile strategy to improve the photovoltaic performance of DSSCs.

  6. Preparation and Characterization of Mn/N Co-Doped TiO2 Loaded on Wood-Based Activated Carbon Fiber and Its Visible Light Photodegradation

    Directory of Open Access Journals (Sweden)

    Xiaojun Ma

    2015-09-01

    Full Text Available Using MnSO4·H2O as manganese source and urea as nitrogen source, Mn/N co-doped TiO2 loaded on wood-based activated carbon fiber (Mn/Ti-N-WACF was prepared by sol–gel method. Mn/Ti-N-WACF with different Mn doping contents was characterized by scanning electron microscopy, X-ray diffraction (XRD and X-ray photoelectron spectroscopies (XPS, and ultraviolet-visible spectrophotometer. Results showed that the loading rate of TiO2 in Mn/Ti-N-WACF was improved by Mn/N co-doping. After calcination at 450 °C, the degree of crystallinity of TiO2 was reduced due to Mn/N co-doption in the resulting Mn/Ti-N-WACF samples, but the TiO2 crystal phase was not changed. XPS spectra revealed that some Ti4+ ions from the TiO2 lattice of Mn/Ti-N-WACF system were substituted by doped Mn. Moreover, new bonds formed within N–Ti–N and Ti–N–O because of the doped N that substituted some oxygen atoms in the TiO2 lattice. Notably, the degradation rate of methylene blue for Mn/Ti-N-WACF was improved because of the co-doped Mn/N under visible-light irradiation.

  7. Photocatalysis-assisted water filtration: Using TiO2-coated vertically aligned multi-walled carbon nanotube array for removal of Escherichia coli O157:H7

    International Nuclear Information System (INIS)

    Oza, Goldie; Pandey, Sunil; Gupta, Arvind; Shinde, Sachin; Mewada, Ashmi; Jagadale, Pravin; Sharon, Maheshwar; Sharon, Madhuri

    2013-01-01

    A porous ceramic was coated with vertically aligned multi-walled carbon nanotubes (MWCNTs) by spray pyrolysis. Titanium dioxide (TiO 2 ) nanoparticles were then coated onto this densely aligned MWCNT. The presence of TiO 2 /MWCNT interfacial arrays was confirmed by X-ray diffraction (XRD), scanning electron microscope–energy dispersive analysis of X-ray (SEM–EDAX) and transmission electron microscope (TEM). This is a novel report in which water loaded with a most dreadful enterohemorrhagic pathogenic strain of Escherichia coli O157:H7 was filtered through TiO 2 /MWCNT coated porous ceramic filter and then analysed. Bacterial removal performance was found to be significantly lower in control i.e. plain porous ceramic (P < 0.05) as compared to TiO 2 /MWCNT coated ceramic. The photocatalytic killing rate constant for TiO 2 -ceramic and MWCNT/TiO 2 -ceramic under fluorescent light was found be 1.45 × 10 −2 min −1 and 2.23 × 10 −2 min −1 respectively. Further, when I–V characteristics were performed for TiO 2 /MWCNT composite, it was corroborated that the current under light irradiation is comparatively higher than that in dark, thus proving it to be photocatalytically efficient system. The enhanced photocatalysis may be a contribution of increased surface area and charge transfer rate as a consequence of aligned MWCNT network. - Highlights: • Coating of vertically aligned MWCNT on ceramic candle filter • Surface orchestration of TiO 2 on MWCNT arrays • I–V characteristic studies are performed under dark and illumination. • Photocatalytic efficiency of TiO 2 /MWCNT arrays is determined using E. coli O157:H7. • Proposed a mechanism of bacterial killing due to free radical formation

  8. Pr3+ doped biphasic TiO2 (rutile-brookite) nanorod arrays grown on activated carbon fibers: Hydrothermal synthesis and photocatalytic properties

    Science.gov (United States)

    Li, Min; Zhang, Xiaomei; Liu, Ying; Yang, Yi

    2018-05-01

    Praseodymium-doped biphasic TiO2 (rutile-brookite) nanorod arrays (Pr-TiO2 NRAs) were successfully prepared via a two-step hydrothermal reaction on activated carbon fibers (ACFs) which pre-coated with TiO2 nanoparticles at first step. The bicrystalline arrays grown on ACFs are primarily constructed by the well-aligned TiO2 nanorods growing along [0 0 1] direction, which were indicated by the results of SEM and XRD. The nanorods are uniform in diameter and length with about 250 nm and 2.5 μm. The composite photocatalyst with high specific surface area and well-aligned nanostructure are beneficial to enhance the adsorption capacity and even help to suppress electron-hole recombination effectively, which consequently revealed much better (2 times) catalytic performance than that of commercially available P25 TiO2 on methylene blue(MB) photodegradation. In addition, the existence of praseodymium in TiO2 gives rise to shift of absorption edge towards long wavelength, which was indicated by the results of UV-vis DRS. Photodegradation results reveal that Pr-doping significantly improves the activity of TiO2, which was 20% higher than that of undoped TiO2 NRAs for the photodegradation of MB in aqueous medium under visible light irradiation. Meanwhile, the doped amount of Pr had a tiny influence on the photocatalytic performance of the composites. In our experiment, 3% Pr-doped molar concentration was proven to be the relatively optimal dopant concentration for the doping of TiO2 NRAs. Moreover, the photocatalyst grown on ACFs substrates is favorable to reuse and photodegradation rate kept on 76% even after 4 times of reuse.

  9. 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.

  10. Photoelectrocatalytic decomposition of ethylene using TiO2/activated carbon fiber electrode with applied pulsed direct current square-wave potential

    International Nuclear Information System (INIS)

    Ye, Sheng-ying; Zheng, Sen-hong; Song, Xian-liang; Luo, Shu-can

    2015-01-01

    Highlights: • Ethylene was decomposed by a photoelectrocatalytic (PEC) process. • A pulsed direct current square-wave (PDCSW) potential was applied to the PEC cell. • An electrode of TiO 2 or modified TiO 2 and activated carbon fiber (ACF) was used. • TiO 2 /ACF photocatalyst electrodes were modified by gamma radiolysis. • Efficiencies of the PEC process were higher than those of the process using DC. - Abstract: Removing ethylene (C 2 H 4 ) from the atmosphere of storage facilities for fruits and vegetable is one of the main challenges in their postharvest handling for maximizing their freshness, quality, and shelf life. In this study, we investigated the photoelectrocatalytic (PEC) degradation of ethylene gas by applying a pulsed direct current DC square-wave (PDCSW) potential and by using a Nafion-based PEC cell. The cell utilized a titanium dioxide (TiO 2 ) photocatalyst or γ-irradiated TiO 2 (TiO 2 * ) loaded on activated carbon fiber (ACF) as a photoelectrode. The apparent rate constant of a pseudo-first-order reaction (K) was used to describe the PEC degradation of ethylene. Parameters of the potential applied to the PEC cell in a reactor that affect the degradation efficiency in terms of the K value were studied. These parameters were frequency, duty cycle, and voltage. Ethylene degradation by application of a constant PDCSW potential to the PEC electrode of either TiO 2 /ACF cell or TiO 2 * /ACF cell enhanced the efficiency of photocatalytic degradation and PEC degradation. Gamma irradiation of TiO 2 in the electrode and the applied PDCSW potential synergistically increased the K value. Independent variables (frequency, duty cycle, and voltage) of the PEC cell fabricated from TiO 2 subjected 20 kGy γ radiation were optimized to maximize the K value by using response surface methodology with quadratic rotation–orthogonal composite experimental design. Optimized conditions were as follows: 358.36 Hz frequency, 55.79% duty cycle, and 64.65 V

  11. Assembling porous carbon-coated TiO2(B)/anatase nanosheets on reduced graphene oxide for high performance lithium-ion batteries

    International Nuclear Information System (INIS)

    Jiang, Shang; Wang, Runwei; Pang, Mingjun; Wang, Hongbin; Zeng, Shangjing; Yue, Xinzheng; Ni, Ling; Yu, Yanru; Dai, Jinyu; Qiu, Shilun; Zhang, Zongtao

    2015-01-01

    Highlights: • Porous carbon-coated mixed-phase Titanium dioxide nanosheets/reduced graphene oxide composites are successfully fabricated. • Carbon coating has been achieved from organic components. • Mesopores are uniformly distributed throughout the whole TiO 2 @C nanosheet. • Excellent cycling stability: the reversible capacity of 158.6 mAh g −1 is achieved at the current density of 800 mA g −1 after 500 cycles. - Abstract: Novel porous carbon-coated mixed-phase porous TiO 2 (TiO 2 (B)/anatase) nanosheets/reduced graphene oxide composites (TiO 2 @C/RGO) are successfully prepared through a facile one-pot solvothermal process followed by subsequent heat treatment in H 2 /Ar. The as-formed composites have a hierarchical porous structure, involving an average pore size of 28.56 nm, a large pore volume of 0.589 cm 3 g −1 and a desired surface area (136.19 m 2 g −1 ). When used as an anode material in LIBs, TiO 2 @C/RGO exhibits stable cycling performance with a reversible capacity of 272.9 mAh g −1 (with the second capacity retention of 151.1%) after 500 cycles at a current density of 100 mA g −1 , much higher than that of TiO 2 @C (177.6 mAh g −1 , 123.9% of the discharge capacity in second cycle) and TiO 2 (75.1 mAh g −1 , corresponding to 96.5% of the original capacity). More impressively, the capacity of TiO 2 @C/RGO can reach 158.6 mAh g −1 after 500 cycles even at 800 mA g −1 with Coulombic efficiency above 99.0%. The superior electrochemical performance of TiO 2 @C/RGO may be attributed to its unique 3D hierarchical porous structures, the existence of carbon, large surface area and extremely reduced diffusion length.

  12. Carbon as amorphous shell and interstitial dopant in mesoporous rutile TiO2: Bio-template assisted sol-gel synthesis and photocatalytic activity

    International Nuclear Information System (INIS)

    Mohamed Azuwa Mohamad; Wan Norharyati Wan Salleh; Juhana Jaafar; Mohamad Saufi Rosmi; Zul Adlan Mohd Hir; Muhazri Abd Mutalib; Ahmad Fauzi Ismail; Tanemura, Masaki

    2017-01-01

    Highlights: • RCM as bio-template and in-situ carbon shell and interstitial carbon doping. • Photo-sensitizers by carbonaceous layer grafted onto the surface of TiO 2 . • Visible light response could be tailored depending on the annealing temperature. • Photocatalytic properties and charge carrier transfer mechanism was proposed. - Abstract: Regenerated cellulose membrane was used as bio-template nanoreactor for the formation of rutile TiO 2 mesoporous, as well as in-situ carbon dopant in acidified sol-gel system. The effects of calcination temperature on the physicochemical characteristic of core-shell nanostructured of bio-templated C-doped mesoporous TiO 2 are highlighted in this study. By varying the calcination temperature, the thickness of the carbon shell coating on TiO 2 , crystallinity, surface area, and optical properties could be tuned as confirmed by HRTEM, nitrogen adsorption/desorption measurement, XRD and UV–vis-NIR spectroscopy. The results suggested that increment in the calcination temperature would lead to the band gap narrowing from 2.95 to 2.80 eV and the thickness of carbon shell increased from 0.40 to 1.20 nm. The x-ray photoelectron spectroscopy showed that the visible light absorption capability was mainly due to the incorporation of carbon dopant at interstitial position in the TiO 2 to form O−Ti−C or Ti−O−C bond. In addition, the formation of the carbon core-shell nanostructured was due to carbonaceous layer grafted onto the surface of TiO 2 via Ti−O−C and Ti−OCO bonds. The result indicated that bio-templated C-doped core-shell mesoporous TiO 2 prepared at 300 °C exhibited the highest photocatalytic activity. It is worthy to note that, the calcination temperature provided a huge impact towards improving the physicochemical and photocatalytic properties of the prepared bio-templated C-doped core-shell mesoporous TiO 2 .

  13. To Reduce of HC and SO2 Emission from Engine’s Exhaust with Local of TiO2 to Inserted in Active Carbon

    International Nuclear Information System (INIS)

    Kris Tri Basuki

    2007-01-01

    The Active carbon can be use to adsorb of emission HC and SO 2 gas from Engine’s exhaust. The result of this research, to make active carbon with 5 cm, 10 cm and 15 cm length in Engine’s exhaust can be reduce of HC are 78.480 %, 81.500 % and 86.320 %. The inserted of 5, 10, 15 % TiO 2 in active carbon with 15 cm length can be reduce of HC are 88.290 %, 91.550 % and 94.920 %. With 5 cm, 10 cm and 15 cm length of variation in Engine’s exhaust can be reduce of SO 2 are 48.630 %, 60.517 % and 60.517 %. The inserted of 5, 10, 15 % TiO 2 in active carbon to make 15 cm length can be reduce of SO 2 are 80.223 %, 82.594 % and 87.696 %. The result of this research to known that the make of 15 % of TiO 2 inserted in active carbon is more effective with 5 % and 10 % of TiO 2 . (author)

  14. Direct access to mesoporous crystalline TiO2/carbon composites with large and uniform pores for use as anode materials in lithium ion batteries

    NARCIS (Netherlands)

    Lee, J.; Jung, Y.S.; Warren, S.C.; Kamperman, M.M.G.; Oh, S.M.; DiSalvo, F.J.; Wiesner, U.

    2011-01-01

    Mesoporous and highly crystalline TiO2 (anatase)/carbon composites with large (>5¿nm) and uniform pores were synthesized using PI-b-PEO block copolymers as structure directing agents. Pore sizes could be tuned by utilizing block copolymers with different molecular weights. The resulting

  15. Fabrication of TiO2@Yeast-Carbon Hybrid Composites with the Raspberry-Like Structure and Their Synergistic Adsorption-Photocatalysis Performance

    Directory of Open Access Journals (Sweden)

    Dang Yu

    2013-01-01

    Full Text Available In the present work, we report the preparation and photocatalytic properties of TiO2@yeast-carbon with raspberry-like structure using a pyrolysis method. The products are characterized by field emission scanning electron microscopy (FE-SEM, energy dispersive spectrometry (EDS, X-ray diffraction (XRD, thermal gravimetric and differential thermal analysis (TGA-DTA, Fourier transformed infrared spectroscopy (FT-IR, and ultraviolet visible spectroscopy (UV-VIS, respectively. The results show that the hybrid TiO2@yeast-carbon microspheres have ordered elliptic shapes of uniform size (length = 3.5±0.3 μm; width = 2.5±0.5 μm. UV-VIS ascertains that the as-prepared microspheres possess an obvious light response in a wide range of 250–400 nm. In the decomposition of typical model pollutants including methylene blue and congo red, the hybrid composites exhibited excellent photocatalytic activity for the methylene blue due to the enhanced adsorption ability. Further investigation reveals that the combined effect of adsorption from the yeast-carbon core and photocatalytic degradation from the attached TiO2 nanoparticles were responsible for the improvement of the photocatalytic activities. Hereby, the raspberry-like TiO2@yeast-carbon has promising applications in water purification.

  16. SnS2 nanosheets arrays sandwiched by N-doped carbon and TiO2 for high-performance Na-ion storage

    Directory of Open Access Journals (Sweden)

    Weina Ren

    2018-01-01

    Full Text Available In this paper, SnS2 nanosheets arrays sandwiched by porous N-doped carbon and TiO2 (TiO2@SnS2@N-C on flexible carbon cloth are prepared and tested as a free-standing anode for high-performance sodium ion batteries. The as-obtained TiO2@SnS2@N-C composite delivers a remarkable capacity performance (840 mA h g−1 at a current density of 200 mA g−1, excellent rate capability and long-cycling life stability (293 mA h g−1 at 1 A g−1 after 600 cycles. The excellent electrochemical performance can be attributed to the synergistic effect of each component of the unique hybrid structure, in which the SnS2 nanosheets with open framworks offer high capacity, while the porous N-doped carbon nanoplates arrays on flexible carbon cloth are able to improve the conductivity and the TiO2 passivation layer can keep the structure integrity of SnS2 nanosheets.

  17. Photocatalysis-assisted water filtration: using TiO2-coated vertically aligned multi-walled carbon nanotube array for removal of Escherichia coli O157:H7.

    Science.gov (United States)

    Oza, Goldie; Pandey, Sunil; Gupta, Arvind; Shinde, Sachin; Mewada, Ashmi; Jagadale, Pravin; Sharon, Maheshwar; Sharon, Madhuri

    2013-10-01

    A porous ceramic was coated with vertically aligned multi-walled carbon nanotubes (MWCNTs) by spray pyrolysis. Titanium dioxide (TiO2) nanoparticles were then coated onto this densely aligned MWCNT. The presence of TiO2/MWCNT interfacial arrays was confirmed by X-ray diffraction (XRD), scanning electron microscope-energy dispersive analysis of X-ray (SEM-EDAX) and transmission electron microscope (TEM). This is a novel report in which water loaded with a most dreadful enterohemorrhagic pathogenic strain of Escherichia coli O157:H7 was filtered through TiO2/MWCNT coated porous ceramic filter and then analysed. Bacterial removal performance was found to be significantly lower in control i.e. plain porous ceramic (Paligned MWCNT network. © 2013 Elsevier B.V. All rights reserved.

  18. TiO2-NT electrodes modified with Ag and diamond like carbon (DLC) for hydrogen production by alkaline water electrolysis

    Science.gov (United States)

    Baran, Evrim; Baz, Zeynep; Esen, Ramazan; Yazici Devrim, Birgül

    2017-10-01

    In present work, the two-step anodization technique was applied for synthesis of TiO2 nanotube (NT). Silver and diamond like carbon (DLC) were coated on the surface of as prepared TiO2-NT using chemical reduction method and MW ECR plasma system. The morphology, composition and structure of the electrodes were examined by field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The results showed that Ag nanoparticles, having size in the range of 48-115 nm, are evenly distributed on the top, inside and outside surface of TiO2-NT and when DLC was coated on the surface of TiO2-NT and TiO2-NT-Ag, the top of nanotubes were partially open and the pore diameter of hexagonal structure decreased from 165 nm to of 38-80 nm. On the other hand, the microhardness test and contact angle measurements revealed that additions of Ag and diamond like carbon have a positive effect on the mechanical properties of TiO2-NT film. The electrocatalytic properties of the electrodes towards the hydrogen evolution reaction (HER) were investigated by the electrochemical measurements recorded in 1 M KOH solution. In addition, long-term durability of electrodes towards HER and the energy consumption of alkaline electrolysis were investigated. The energy requirement showed that while the deposition of silver provides approximately 14.95% savings of the energy consumption, the DLC coating causes increase in energy consumption.

  19. Self-assembly graphitic carbon nitride quantum dots anchored on TiO_2 nanotube arrays: An efficient heterojunction for pollutants degradation under solar light

    International Nuclear Information System (INIS)

    Su, Jingyang; Zhu, Lin; Geng, Ping; Chen, Guohua

    2016-01-01

    Highlights: • Carbon nitride quantum dots (CNQDs) were decorated onto TiO_2 nanotube arrays (NTAs). • The CNQDs/TiO_2 NTAs exhibits much improved photoelectrochemical activity. • The heterojunction displays efficient removal efficiencies for RhB and phenol. • Pollutants degradation mechanism over CNQDs/TiO_2 NTAs was clarified. - Abstract: In this study, an efficient heterojunction was constructed by anchoring graphitic carbon nitride quantum dots onto TiO_2 nanotube arrays through hydrothermal reaction strategy. The prepared graphitic carbon nitride quantum dots, which were prepared by solid-thermal reaction and sequential dialysis process, act as a sensitizer to enhance light absorption. Furthermore, it was demonstrated that the charge transfer and separation in the formed heterojunction were significantly improved compared with pristine TiO_2. The prepared heterojunction was used as a photoanode, exhibiting much improved photoelectrochemical capability and excellent photo-stability under solar light illumination. The photoelectrocatalytic activities of prepared heterojunction were demonstrated by degradation of RhB and phenol in aqueous solution. The kinetic constants of RhB and phenol degradation using prepared photoelectrode are 2.4 times and 4.9 times higher than those of pristine TiO_2, respectively. Moreover, hydroxyl radicals are demonstrated to be dominant active radicals during the pollutants degradation.

  20. Síntese, caracterização e atividade fotocatalítica de catalisadores nanoestruturados de TiO2 dopados com metais Synthesis, characterization and photocatalytic activity of nanostructured TiO2 catalysts doped with metals

    Directory of Open Access Journals (Sweden)

    William Leonardo da Silva

    2013-01-01

    Full Text Available Titanium dioxide nanostructured catalysts (nanotubes doped with different metals (silver, gold, copper, palladium and zinc were synthesized by the hydrothermal method in order to promote an increase in their photocatalytic activity under visible light. The catalysts were characterized by X-ray diffraction, diffuse reflectance spectroscopy, transmission electron microscopy and specific area and pore volume determination. The materials' photocatalytic activity was evaluated by rhodamine B decomposition in a glass batch reactor. Under UV radiation, only nanotubes doped with palladium were more active than the TiO2 P25, but the samples doped with silver, palladium and gold exhibited better results than the undoped samples under visible light.

  1. Carbon Domains on MoS2/TiO2 System via Catalytic Acetylene Oligomerization: Synthesis, Structure, and Surface Properties

    Directory of Open Access Journals (Sweden)

    Sara Cravanzola

    2017-11-01

    Full Text Available Carbon domains have been obtained at the surface of a MoS2/TiO2 (Evonik, P25 system via oligomerization and cyclotrimerization reactions involved in the interaction of the photoactive material with acetylene. Firstly, MoS2 nanosheets have been synthesized at the surface of TiO2, via sulfidation of a molybdenum oxide precursor with H2S (bottom-up method. Secondly, the morphology and the structure, the optical and the vibrational properties of the obtained materials, for each step of the synthesis procedure, have been investigated by microscopy and spectroscopy methods. In particular, transmission electron microscopy images provide a simple tool to highlight the effectiveness of the sulfidation process, thus showing 1L, 2L, and stacked MoS2 nanosheets anchored to the surface of TiO2 nanoparticles. Lastly, in-situ FTIR spectroscopy investigation gives insights into the nature of the oligomerized species, showing that the formation of both polyenic and aromatic systems can be taken into account, being their formation promoted by both Ti and Mo catalytic sites. This finding gives an opportunity for the assembly of extended polyenic, polyaromatic, or mixed domains firmly attached at the surface of photoactive materials. The presented approach, somehow different from the carbon adding or doping processes of TiO2, is of potential interest for the advanced green chemistry and energy conversion/transport applications.

  2. Influence of Cu, TiO2 Nanoparticles and Carbon Nano-Horns on Tribological Properties of Engine Oil.

    Science.gov (United States)

    Zin, V; Agresti, F; Barison, S; Colla, L; Fabrizio, M

    2015-05-01

    The addition of nanoparticles in lubricating oils recently demonstrated to reduce the coefficient of friction and to increase the load-carrying capability of lubricant in coupled surfaces. In this work, different kinds of nanoparticles were tested as additives to engine oil to improve lubrication: copper and titanium oxide nanoparticles and single walled carbon nanohorns (SWCNHs). Two nanoparticle sizes were also tested in case of copper. The tribological properties of these nanofluids were evaluated by Stribeck tests, in order to compare the effect of nanoparticles on friction coefficient and electric contact resistance in different lubrication regimes. Stribeck curves showed that the coefficient of friction was reduced, compared to raw oil, by the action of Cu nanoparticles having 130 nm diameter, leading to a mean decrease of about 17%, and by SWCNHs, with a mean decrease of about 12%. Conversely, no significant changes were detected in presence of Cu nanoparticles having 50 nm diameter or of TiO2. The suspension viscosity and stability were also tested. Wear tests were also carried out, showing a reduction of wear rate up to nearly 50% for Cu nanoparticles (150 nm diameter) and around 30% for SWCNHs. The measurements showed that nanoparticles having size comparable to the mean roughness of coupled surfaces significantly improved the tribological properties of bare oil. An explanation of nanoparticle action is proposed.

  3. High-Performance Li-Ion Capacitor Based on an Activated Carbon Cathode and Well-Dispersed Ultrafine TiO2 Nanoparticles Embedded in Mesoporous Carbon Nanofibers Anode.

    Science.gov (United States)

    Yang, Cheng; Lan, Jin-Le; Liu, Wen-Xiao; Liu, Yuan; Yu, Yun-Hua; Yang, Xiao-Ping

    2017-06-07

    A novel Li-ion capacitor based on an activated carbon cathode and a well-dispersed ultrafine TiO 2 nanoparticles embedded in mesoporous carbon nanofibers (TiO 2 @PCNFs) anode was reported. A series of TiO 2 @PCNFs anode materials were prepared via a scalable electrospinning method followed by carbonization and a postetching method. The size of TiO 2 nanoparticles and the mesoporous structure of the TiO 2 @PCNFs were tuned by varying amounts of tetraethyl orthosilicate (TEOS) to increase the energy density and power density of the LIC significantly. Such a subtle designed LIC displayed a high energy density of 67.4 Wh kg -1 at a power density of 75 W kg -1 . Meanwhile, even when the power density was increased to 5 kW kg -1 , the energy density can still maintain 27.5 Wh kg -1 . Moreover, the LIC displayed a high capacitance retention of 80.5% after 10000 cycles at 10 A g -1 . The outstanding electrochemical performance can be contributed to the synergistic effect of the well-dispersed ultrafine TiO 2 nanoparticles, the abundant mesoporous structure, and the conductive carbon networks.

  4. TiO2 Photocatalyst Nanoparticle Separation: Flocculation in Different Matrices and Use of Powdered Activated Carbon as a Precoat in Low-Cost Fabric Filtration

    Directory of Open Access Journals (Sweden)

    Carlos F. Liriano-Jorge

    2014-01-01

    Full Text Available Separation of photocatalyst nanoparticles is a problem impeding widespread application of photocatalytic oxidation. As sedimentation of photocatalyst particles is facilitated by their flocculation, the influence of common constituents of biologically pretreated wastewaters (NaCl, NaHCO3, and their combination with humic acid sodium salt on flocculation was tested by the pipet method. Results showed that the impact of these substances on TiO2 nanoparticle flocculation is rather complex and strongly affected by pH. When humic acid was present, TiO2 particles did not show efficient flocculation in the neutral and slightly basic pH range. As an alternative to photocatalyst separation by sedimentation, precoat vacuum filtration with powdered activated carbon (PAC over low-cost spunbond polypropylene fabrics was tested in the presence of two PAC types in aqueous NaCl and NaHCO3 solutions as well as in biologically treated greywater and in secondary municipal effluent. PAC concentrations of ≥2 g/L were required in order to achieve a retention of nearly 95% of the TiO2 nanoparticles on the fabric filter when TiO2 concentration was 1 g/L. Composition of the aqueous matrix and PAC type had a slight impact on precoat filtration. PAC precoat filtration represents a potential pretreatment for photocatalyst removal by micro- or ultrafiltration.

  5. Synthesis of TiO2 nanoparticles containing Fe, Si, and V using multiple diffusion flames and catalytic oxidation capability of carbon-coated nanoparticles

    KAUST Repository

    Ismail, Mohamed

    2016-01-19

    Titanium dioxide (TiO2) nanoparticles containing iron, silicon, and vanadium are synthesized using multiple diffusion flames. The growth of carbon-coated (C–TiO2), carbon-coated with iron oxide (Fe/C–TiO2), silica-coated (Si–TiO2), and vanadium-doped (V–TiO2) TiO2 nanoparticles is demonstrated using a single-step process. Hydrogen, oxygen, and argon are utilized to establish the flame, with titanium tetraisopropoxide (TTIP) as the precursor for TiO2. For the growth of Fe/C–TiO2 nanoparticles, TTIP is mixed with xylene and ferrocene. While for the growth of Si–TiO2 and V–TiO2, TTIP is mixed with hexamethyldisiloxane (HMDSO) and vanadium (V) oxytriisopropoxide, respectively. The synthesized nanoparticles are characterized using high-resolution transmission electron microscopy (HRTEM) with energy-filtered TEM for elemental mapping (of Si, C, O, and Ti), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), nitrogen adsorption BET surface area analysis, and thermogravimetric analysis. Anatase is the dominant phase for the C–TiO2, Fe/C–TiO2, and Si–TiO2 nanoparticles, whereas rutile is the dominant phase for the V–TiO2 nanoparticles. For C–TiO2 and Fe/C–TiO2, the nanoparticles are coated with about 3-5-nm thickness of carbon. The iron-based TiO2 nanoparticles significantly improve the catalytic oxidation of carbon, where complete oxidation of carbon occurs at a temperature of 470 °C (with iron) compared to 610 °C (without iron). Enhanced catalytic oxidation properties are also observed for model soot particles, Printex-U, when mixed with Fe/C-TiO2. With regards to Si–TiO2 nanoparticles, a uniform coating of 3 to 8 nm of silicon dioxide is observed around the TiO2 particles. This coating mainly occurs due to variance in the chemical reaction rates of the precursors. Finally, with regards to V–TiO2, vanadium is doped within the TiO2 nanoparticles as visualized by HRTEM and XPS further confirms the formation of

  6. Synthesis of TiO2 nanoparticles containing Fe, Si, and V using multiple diffusion flames and catalytic oxidation capability of carbon-coated nanoparticles

    KAUST Repository

    Ismail, Mohamed; Memon, Nasir K.; Hedhili, Mohamed N.; Anjum, Dalaver H.; Chung, Suk-Ho

    2016-01-01

    Titanium dioxide (TiO2) nanoparticles containing iron, silicon, and vanadium are synthesized using multiple diffusion flames. The growth of carbon-coated (C–TiO2), carbon-coated with iron oxide (Fe/C–TiO2), silica-coated (Si–TiO2), and vanadium-doped (V–TiO2) TiO2 nanoparticles is demonstrated using a single-step process. Hydrogen, oxygen, and argon are utilized to establish the flame, with titanium tetraisopropoxide (TTIP) as the precursor for TiO2. For the growth of Fe/C–TiO2 nanoparticles, TTIP is mixed with xylene and ferrocene. While for the growth of Si–TiO2 and V–TiO2, TTIP is mixed with hexamethyldisiloxane (HMDSO) and vanadium (V) oxytriisopropoxide, respectively. The synthesized nanoparticles are characterized using high-resolution transmission electron microscopy (HRTEM) with energy-filtered TEM for elemental mapping (of Si, C, O, and Ti), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), nitrogen adsorption BET surface area analysis, and thermogravimetric analysis. Anatase is the dominant phase for the C–TiO2, Fe/C–TiO2, and Si–TiO2 nanoparticles, whereas rutile is the dominant phase for the V–TiO2 nanoparticles. For C–TiO2 and Fe/C–TiO2, the nanoparticles are coated with about 3-5-nm thickness of carbon. The iron-based TiO2 nanoparticles significantly improve the catalytic oxidation of carbon, where complete oxidation of carbon occurs at a temperature of 470 °C (with iron) compared to 610 °C (without iron). Enhanced catalytic oxidation properties are also observed for model soot particles, Printex-U, when mixed with Fe/C-TiO2. With regards to Si–TiO2 nanoparticles, a uniform coating of 3 to 8 nm of silicon dioxide is observed around the TiO2 particles. This coating mainly occurs due to variance in the chemical reaction rates of the precursors. Finally, with regards to V–TiO2, vanadium is doped within the TiO2 nanoparticles as visualized by HRTEM and XPS further confirms the formation of

  7. TiO2/Halloysite Composites Codoped with Carbon and Nitrogen from Melamine and Their Enhanced Solar-Light-Driven Photocatalytic Performance

    Directory of Open Access Journals (Sweden)

    Pengcheng Yao

    2015-01-01

    Full Text Available Carbon (C and nitrogen (N codoped anatase TiO2/amorphous halloysite nanotubes (C+N-TiO2/HNTs were fabricated using melamine as C and N source. The samples prepared by different weight ratios of melamine and TiO2 were investigated by X-ray diffraction (XRD and UV-vis diffuse reflectance spectrometer. It is shown that the doping amounts of C and N could influence the photocatalytic performance of as-prepared composites. When the weight ratio of melamine/TiO2 is 4.5, the C+N-TiO2/HNTs exhibited the best photocatalytic degradation efficiency of methyl blue (MB under solar light irradiation. The obtained C+N-TiO2/HNTs were characterized by transmission electron microscopy (TEM, N2 adsorption-desorption isotherm (BET, X-ray photoelectron spectroscopy (XPS, and Fourier transform infrared spectrum (FT-IR. The results showed that the aggregation was effectively reduced, and TiO2 nanoparticles could be uniformly deposited on the surface of HNTs. This leads to an increase of their specific surface area. XPS and FT-IR analyses indicated TiO2 particles were doped successfully with C and N via the linkage of the Ti–O–N, O–Ti–N, and Ti–O–C. Photocatalytic experiments showed that C+N-TiO2/HNTs had higher degradation efficiency of MB than TiO2/HNTs. This makes the composite a potential candidate for the photocatalytic wastewater treatment.

  8. TiO2 Immobilized on Manihot Carbon: Optimal Preparation and Evaluation of Its Activity in the Decomposition of Indigo Carmine

    Science.gov (United States)

    Antonio-Cisneros, Cynthia M.; Dávila-Jiménez, Martín M.; Elizalde-González, María P.; García-Díaz, Esmeralda

    2015-01-01

    Applications of carbon-TiO2 materials have attracted attention in nanotechnology due to their synergic effects. We report the immobilization of TiO2 on carbon prepared from residues of the plant Manihot, commercial TiO2 and glycerol. The objective was to obtain a moderate loading of the anatase phase by preserving the carbonaceous external surface and micropores of the composite. Two preparation methods were compared, including mixing dry precursors and immobilization using a glycerol slurry. The evaluation of the micropore blocking was performed using nitrogen adsorption isotherms. The results indicated that it was possible to use Manihot residues and glycerol to prepare an anatase-containing material with a basic surface and a significant SBET value. The activities of the prepared materials were tested in a decomposition assay of indigo carmine. The TiO2/carbon eliminated nearly 100% of the dye under UV irradiation using the optimal conditions found by a Taguchi L4 orthogonal array considering the specific surface, temperature and initial concentration. The reaction was monitored by UV-Vis spectrophotometry and LC-ESI-(Qq)-TOF-MS, enabling the identification of some intermediates. No isatin-5-sulfonic acid was detected after a 60 min photocatalytic reaction, and three sulfonated aromatic amines, including 4-amino-3-hydroxybenzenesulfonic acid, 2-(2-amino-5-sulfophenyl)-2-oxoacetic acid and 2-amino-5-sulfobenzoic acid, were present in the reaction mixture. PMID:25588214

  9. TiO2 Immobilized on Manihot Carbon: Optimal Preparation and Evaluation of Its Activity in the Decomposition of Indigo Carmine

    Directory of Open Access Journals (Sweden)

    Cynthia M. Antonio-Cisneros

    2015-01-01

    Full Text Available Applications of carbon-TiO2 materials have attracted attention in nanotechnology due to their synergic effects. We report the immobilization of TiO2 on carbon prepared from residues of the plant Manihot, commercial TiO2 and glycerol. The objective was to obtain a moderate loading of the anatase phase by preserving the carbonaceous external surface and micropores of the composite. Two preparation methods were compared, including mixing dry precursors and immobilization using a glycerol slurry. The evaluation of the micropore blocking was performed using nitrogen adsorption isotherms. The results indicated that it was possible to use Manihot residues and glycerol to prepare an anatase-containing material with a basic surface and a significant SBET value. The activities of the prepared materials were tested in a decomposition assay of indigo carmine. The TiO2/carbon eliminated nearly 100% of the dye under UV irradiation using the optimal conditions found by a Taguchi L4 orthogonal array considering the specific surface, temperature and initial concentration. The reaction was monitored by UV-Vis spectrophotometry and LC-ESI-(Qq-TOF-MS, enabling the identification of some intermediates. No isatin-5-sulfonic acid was detected after a 60 min photocatalytic reaction, and three sulfonated aromatic amines, including 4-amino-3-hydroxybenzenesulfonic acid, 2-(2-amino-5-sulfophenyl-2-oxoacetic acid and 2-amino-5-sulfobenzoic acid, were present in the reaction mixture.

  10. 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.

  11. Effect of photocatalytic reduction of carbon dioxide by N-Zr co-doped nano TiO2.

    Science.gov (United States)

    Zhang, Ru; Wang, Li; Kang, Zhuo; Li, Qiang; Pan, Huixian

    2017-11-01

    Modified sol-gel method was adopted to prepare TiO 2 , Zr-TiO 2 and N/Zr-TiO 2 composite catalyst. The as-synthesized photocatalysts were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Brunner- Emmet- Teller measurement and UV-Vis diffuse reflectance spectroscopy. And the photocatalytic performance toward CO 2 reduction was evaluated under ultraviolet light. The catalyst particles were demonstrated in the nanometer level size. When N and Zr are co-doped, on the one hand, Ti 4+ can be replaced by Zr 4  +, which leads to lattice distortion and inhibits electron-hole recombination. On the other hand, N enters into TiO 2 lattice gap to form O-Ti-N bond structure, and partial Ti 4+ are reduced to Ti 3+ . Compared with pristine TiO 2 , the specific surface area and the band gap of N/Zr-TiO 2 were improved and reduced, respectively. The N and Zr synergistically contribute to the obviously strengthened absorption intensity in visible region, as well as significantly improved photocatalytic activity. In the gas phase reactor, when the calcination temperature was 550°C, 0.125N/0.25Zr-TiO 2 composite performed the highest photocatalytic activity UV irradiation for 8 h, and the corresponding CH 4 yield was 11.837 µmol/g, which was 87.8% higher than that of pristine TiO 2 . For the visible light, the CH 4 yield was 9.003 µmol/g after 8 h irradiation, which was 83.9% higher than that of pristine TiO 2 .

  12. Single-walled carbon nanotube-facilitated dispersion of particulate TiO2 on ZrO2 ceramic membrane filters.

    Science.gov (United States)

    Yao, Yuan; Li, Gonghu; Gray, Kimberly A; Lueptow, Richard M

    2008-07-15

    We report that SWCNTs substantially improve the uniformity and coverage of TiO2 coatings on porous ZrO2 ceramic membrane filters. The ZrO2 filters were dip coated with 100 nm anatase TiO2, TiO2/SWCNT composites, a TiO2+SWCNT mixture, and a TiO2/MWCNT composite at pH 3, 5, and 8. Whereas the TiO2+SWCNT mixture and the TiO2/MWCNT composite promote better coverage and less clumping than TiO2 alone, the TiO2/SWCNT composite forms a complete uniform coating without cracking at pH 5 ( approximately 100% coverage). A combination of chemical and electrostatic effects between TiO2 and SWCNTs forming the composite as well as between the composite and the ZrO2 surface explains these observations.

  13. Síntese, caracterização e atividade fotocatalítica de catalisadores nanoestruturados de TiO2 dopados com metais

    Directory of Open Access Journals (Sweden)

    William Leonardo da Silva

    2013-01-01

    Full Text Available Titanium dioxide nanostructured catalysts (nanotubes doped with different metals (silver, gold, copper, palladium and zinc were synthesized by the hydrothermal method in order to promote an increase in their photocatalytic activity under visible light. The catalysts were characterized by X-ray diffraction, diffuse reflectance spectroscopy, transmission electron microscopy and specific area and pore volume determination. The materials' photocatalytic activity was evaluated by rhodamine B decomposition in a glass batch reactor. Under UV radiation, only nanotubes doped with palladium were more active than the TiO2 P25, but the samples doped with silver, palladium and gold exhibited better results than the undoped samples under visible light.

  14. Comparison between nano-diamond and carbon nanotube doping effects on critical current density and flux pinning in MgB2

    International Nuclear Information System (INIS)

    Cheng, C H; Yang, Y; Munroe, P; Zhao, Y

    2007-01-01

    Doping effects of nano-diamond and carbon nanotubes (CNTs) on critical current density of bulk MgB 2 have been studied. CNTs are found prone to be doped into the MgB 2 lattice whereas nano-diamond tends to form second-phase inclusions in the MgB 2 matrix, leading to a more significant improvement of J c (H) by doping by nano-diamond than by CNTs in MgB 2 . TEM reveals tightly packed MgB 2 nanograins (50-100 nm) with a dense distribution of diamond nanoparticles (10-20 nm) inside MgB 2 grains in nano-diamond-doped samples. Such a unique microstructure leads to a flux pinning behaviour different from that in CNTs-doped MgB 2

  15. 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

  16. TiO2-Containing Carbon Derived from a Metal-Organic Framework Composite: A Highly Active Catalyst for Oxidative Desulfurization.

    Science.gov (United States)

    Bhadra, Biswa Nath; Song, Ji Yoon; Khan, Nazmul Abedin; Jhung, Sung Hwa

    2017-09-13

    A new metal-organic framework (MOF) composite consisting of Ti- and Zn-based MOFs (ZIF-8(x)@H 2 N-MIL-125; in brief, ZIF(x)@MOF) was designed and synthesized. The pristine MOF [H 2 N-MIL-125 (MOF)]- and an MOF-composite [ZIF(30)@MOF]-derived mesoporous carbons consisting of TiO 2 nanoparticles were prepared by pyrolysis (named MDC-P and MDC-C, respectively). MDC-C showed a higher surface area, larger pore sizes, and larger mesopore volumes than MDC-P. In addition, the TiO 2 nanoparticles on MDC-C have more uniform shapes and sizes and are smaller than those of MDC-P. The obtained MDC-C and MDC-P [together with MOF, ZIF(30)@MOF, pure/nanocrystalline TiO 2 , and activated carbon] were applied in the oxidative desulfurization reaction of dibenzothiophene in a model fuel. The MDC-C, even with a lower TiO 2 content than that of MDC-P, showed an outstanding catalytic performance, especially with a very low catalyst dose (i.e., a very high quantity of dibenzothiophene was converted per unit weight of the catalyst), fast kinetics (∼3 times faster than that for MDC-P), and a low activation energy (lower than that for any reported catalyst) for the oxidation of dibenzothiophene. The large mesopores of MDC-C and the well-dispersed/small TiO 2 might be the dominant factors for the superior catalytic conversions. The oxidative desulfurization of other sulfur-containing organic compounds with various electron densities was also studied with MDC-C to understand the mechanism of catalysis. Moreover, the MDC-C catalyst can be reused many times in the oxidative desulfurization reaction after a simple washing with acetone. Finally, composing MOFs and subsequent pyrolysis is suggested as an effective way to prepare a catalyst with well-dispersed active sites, large pores, and high mesoporosity.

  17. TiO2 nanoparticles immobilized on carbon nanotubes for enhanced visible-light photo-induced activity

    Directory of Open Access Journals (Sweden)

    Ali Akbar Ashkarran

    2015-04-01

    Full Text Available CNT–TiO2 nanocomposites were prepared through (i simple mixing of as prepared CNTs and TiO2 nanoparticles (NPs, (ii simple mixing of as prepared CNTs and TiO2 NPs followed by heat treatment and (iii simple mixing of as prepared CNTs and TiO2 NPs followed by UV illumination. The synthesis of CNTs and TiO2 NPs were performed individually by arc discharge in water and sol–gel methods, respectively and characterized by X-ray diffraction (XRD, ultra violet and visible spectroscopy (UV–vis, Fourier transform infrared spectroscopy (FT-IR, scanning electron microscopy (SEM and transmission electron microscopy (TEM. The visible-light photocatalytic performance of CNT–TiO2 nanocomposites was successfully demonstrated for the degradation of Rhodamine B (Rh. B as a model dye at room temperature. It is found that CNT–TiO2 nanocomposites extended the light absorption spectrum toward the visible region and considerably improved the photocatalytic efficiency under visible-light irradiation. The visible-light photocatalytic activities of CNT–TiO2 nanocomposites in which CNTs are produced by arc discharge in deionized (DI water at 40, 60 and 80 A arc currents and combined through three different protocols are also investigated. It was found that samples prepared at 80 A arc current and 5 s arc duration followed by UV illumination revealed best photocatalytic activity compared with the same samples prepared under simple mixing and simple mixing followed by heat treatment. The enhancement in the photocatalytic property of CNT–TiO2 nanocomposites prepared at 80 A arc current followed by UV illumination may be ascribed to the quality of CNTs produced at this current, as was reported before.

  18. Double-layer Electromagnetic Wave Absorber Based on Carbon Nanotubes Doped with La(NO33 and Fe3O4 Nanoparticles

    Directory of Open Access Journals (Sweden)

    Cuiling HOU

    2017-08-01

    Full Text Available Double-layer structure absorbing materials based on the impedance matching principle and transmission line theory can effectively improve the electromagnetic wave absorbing properties. In this paper, the electro-magnetic wave absorbing properties of double-layer absorbers (2 mm thickness, where multiwall carbon nanotube (MWCNT-La(NO33/polyvinyl chloride (PVC and MWCNT-Fe3O4/PVC composites had been taken turns as the absorption layer and matching layer, were investigated in 2 – 18 GHz range. The absorbing properties of single- and double-layer structure and different each-layer thickness with two types of combinations were compared. The results showed that the design of double-layer structure for composites could effectively broaden the absorption frequency area, and increase the absorption intensity. When MWCNT-La(NO33/PVC composite were used as absorption layers with 0.6 mm thickness, the absorption bandwidth (< – 15 dB or > 97 % of double-layer composite was the widest, reaching a maximum of about 3.36 GHz, and the absorption peak value was also the lowest about – 46.02 dB at 16.24 GHz.DOI: http://dx.doi.org/10.5755/j01.ms.23.3.16279

  19. First principles studies of the electronic properties and catalytic activity of single-walled carbon nanotube doped with Pt clusters and chains

    International Nuclear Information System (INIS)

    Hayes, Kayla E.; Lee, Hee-Seung

    2012-01-01

    Highlights: ► Electronic and magnetic properties of (5, 5)-SWNT doped with Pt clusters and chains. ► Pt-doping can change metallic (5, 5)-SWNT to semiconducting CNT. ► Oxygen adsorption on Pt-doped (5, 5)-SWNT is barrierless process. ► Pt-doping reduces the activation barrier of oxygen dissociation reaction. ► Adsorbed oxygen has 2 O 2 - – character. - Abstract: We report the results of density functional theory calculations on the electronic structures, geometrical parameters, and magnetic properties of a wide variety of Pt clusters/chains adsorbed on metallic (5,5) single-walled carbon nanotube (SWNT). It was found that the electronic band structures of Pt/CNT systems are very sensitive to the small changes in the geometries of Pt clusters and chains. In some cases, metallic (5, 5)-SWNT becomes a small-gap semiconducting nanotube with adsorbed Pt clusters and chains. We also investigated the dissociation of molecular oxygen on the (5, 5)-SWNT doped with a single Pt atom via the nudged elastic band (NEB) method. The NEB results showed that the activation barrier is lowered even with a single Pt atom compared to that of pristine SWNT. It was found that the electronic structure of molecular oxygen adsorbed on Pt-doped CNT resembles that of 2 O 2 - , which should facilitate the dissociation process.

  20. Effect of beam expansion loss in a carbon nanotube-doped PVA film on passively mode-locked erbium-doped fiber lasers with different feedback ratios

    International Nuclear Information System (INIS)

    Cheng, Kuang-Nan; Chi, Yu-Chieh; Cheng, Chih-Hsien; Lin, Yung-Hsiang; Lo, Jui-Yung; Lin, Gong-Ru

    2014-01-01

    The effect of beam expansion induced divergent loss in a single-wall carbon nanotube (SWCNT) doped polyvinyl alcohol (PVA) based ultrafast saturable absorber (SA) film thickness on the passive mode-locking (PML) performances of erbium-doped fiber lasers are demonstrated. The variation on the PML pulsewidth of the EDFL is discussed by changing the SWCNT-PVA SA film thicknesses, together with adjusting the pumping power and the intra-cavity feedback ratio. An almost 6 dB increment of divergent loss when enlarging the SWCNT-PVA based SA film thickness from 30–130 µm is observed. When shrinking the SA thickness to 30 µm at the largest pumping power of 52.5 mW, the optical spectrum red-shifts to 1558.8 nm with its 3 dB spectral linewidth broadening up to 2.7 nm, while the pulse has already entered the soliton regime with multi-order Kelly sidebands aside the spectral shoulder. The soliton pulsewidth is as short as 790 fs, which is much shorter than those obtained with other thicker SWCNT doped PVA polymer film based SAs; therefore, the peak power from the output of the PML-EDFL is significantly enlarged accompanied by a completely suppressed residual continuous-wave level to achieve the largest on/off extinction ratio. The main mechanism of pulse shortening with reducing thickness of SWCNT doped PVA polymer film based SA is attributed to the limited beam expansion as well as the enlarged modulation depth, which results in shortened soliton pulsewidth with a clean dc background, and broadened spectrum with enriched Kelly sidebands. The increase of total SWCNT amount in the thicker SA inevitably causes a higher linear absorption; hence, the mode-locking threshold also rises accordingly. By enlarging pumping power from 38.5–52.5 mW, the highest ascent on pulse extinction of up to 32 dB is observed among all kinds of feedback conditions. Nevertheless, the enlargement on the extinction slightly decays with increasing the feedback ratio from 30–90

  1. Enhancing the photocatalytic properties of TiO2 by coupling with carbon nanotubes and supporting gold

    International Nuclear Information System (INIS)

    Wang, Huihu; Dong, Shijie; Chang, Ying; Faria, Joaquim L.

    2012-01-01

    Highlights: ► Au–CNT–TiO 2 composites were synthesized by coupling CNT and Au to TiO 2 . ► The activity of Au–CNT–TiO 2 materials is higher than that of CNT–TiO 2 and Au–TiO 2 . ► The Au–CNT–TiO 2 composites possess both advantages of CNTs and Au. ► The Au–CNT–TiO 2 composites also overcome the disadvantages of surplus CNTs addition. - Abstract: The photodegradation of methylene blue in aqueous solutions is studied using various photocatalysts, including neat TiO 2 , CNT–TiO 2 , Au–TiO 2 , and Au–CNT–TiO 2 composites MB. Materials were synthesized and extensively characterized by XRD, TEM, DRFIT spectroscopy, N 2 adsorption–desorption isotherms, as well as diffuse reflectance UV–vis spectroscopy. By using CNT–TiO 2 composite as catalysts, it was found that CNT act as adsorbent and photosensitizer to improve the photoactivity of neat TiO 2 . Among the CNT–TiO 2 composites with different CNT weight ratio (0.2–20%), the 2%CNT–TiO 2 shows the best photoactivity. When CNT content is larger than 2%, the surplus CNT may absorb and scatter light photons. Combined with the decrease of TiO 2 amount in composite, the photoactivity is reduced. To further improve the photoactivity of 2%CNT–TiO 2 , different Au loads varying from 0.25% to 1% were introduced by the deposition–precipitation method. The 0.25%Au–2%CNT–TiO 2 composite had the highest photoactivity. The increase in activity was explained by the surface plasmon resonance of Au that makes the composite to absorb more photons than the 2%CNT–TiO 2 , thus overcoming the disadvantages of surplus CNT addition. On the other hand, 0.25%Au–2%CNT–TiO 2 composite also presents higher activity than 0.25%Au–TiO 2 due to higher adsorption capacity provided by CNT introduction. The addition of CNT and Au simultaneously has a much stronger synergic role than when each of them is introduced individually.

  2. Effective Carbon Dioxide Photoreduction over Metals (Fe-, Co-, Ni-, and Cu- Incorporated TiO2/Basalt Fiber Films

    Directory of Open Access Journals (Sweden)

    Jeong Yeon Do

    2016-01-01

    Full Text Available Mineralogical basalt fibers as a complementary adsorbent were introduced to improve the adsorption of CO2 over the surfaces of photocatalysts. TiO2 photocatalysts (M-TiO2 incorporated with 5.0 mol.% 3d-transition metals (Fe, Co, Ni, and Cu were prepared using a solvothermal method and mixed with basalt fibers for applications to CO2 photoreduction. The resulting 5.0 mol.% M-TiO2 powders were characterized by X-ray diffraction, scanning electron microscopy, ultraviolet-visible spectroscopy, photoluminescence, Brunauer, Emmett, and Teller surface area, and CO2-temperature-programmed desorption. A paste composed of two materials was coated and fixed on a Pyrex plate by a thermal treatment. The 5.0 mol.% M-TiO2/basalt fiber films increased the adsorption of CO2 significantly, indicating superior photocatalytic behavior compared to pure TiO2 and basalt fiber films, and produced 158~360 μmol gcat-1 L−1 CH4 gases after an 8 h reaction. In particular, the best performance was observed over the 5.0 mol.% Co-TiO2/basalt fiber film. These results were attributed to the effective CO2 gas adsorption and inhibition of photogenerated electron-hole pair recombination.

  3. Toxicological consequences of TiO2, SiC nanoparticles and multi-walled carbon nanotubes exposure in several mammalian cell types: an in vitro study

    International Nuclear Information System (INIS)

    Barillet, Sabrina; Simon-Deckers, Angelique; Herlin-Boime, Nathalie; Mayne-L'Hermite, Martine; Reynaud, Cecile; Cassio, Doris; Gouget, Barbara; Carriere, Marie

    2010-01-01

    The development of nanotechnologies may lead to dissemination of potentially toxic nanoparticles in the environment. Toxicology of these nano-sized particles is thus attracting attention of public and governments worldwide. Our research is focused on the in vitro response of eukaryotic cells to nanoparticles exposure. For this purpose, we used cellular models of primary target organs (lung: A549 alveolar epithelial cells), or secondary target organs (liver: WIF-B9, Can-10 and kidneys: NRK-52E, LLC-PK1 proximal cells), i.e., organs exposed if nanoparticles are translocated through epithelial barriers. These cells were exposed to TiO 2 , SiC nanoparticles or multi-walled carbon nanotubes (MWCNT). The influence of nanoparticles physico-chemical characteristics on various toxicological endpoints (cytotoxicity, reactive oxygen species generation, genotoxicity) was specified. Our data demonstrate that nanoparticles toxicity depend on their size, morphology, and chemical composition, the finest, spherical shaped, and anatase TiO 2 nanoparticles being the more cytotoxic to NRK-52E cells, while SiC nanoparticles exert almost no cytotoxicity. MWCNT cytotoxicity neither depended on their length, nor on the presence of metal impurities. Nanoparticles cytotoxicity also depended on the exposed cell line. All the tested nanoparticles were uptaken by cells and caused intracellular reactive oxygen species generation. Relative to genotoxic effects, DNA strand breaks were detected in NRK-52E cells via the alkaline comet assay after exposure of cells to TiO 2 nanoparticles and to a lesser extent after exposure to MWCNT, but no double strand breaks were detected. The originality of this study lies on the panel of nanomaterials which were tested on a variety of cell lines. All these data may lead to a better understanding of nanomaterial toxicity and hazards for health.

  4. Adsorption of carbon dioxide on TEPA-modified TiO_2/titanate composite nano-rods

    International Nuclear Information System (INIS)

    Kapica-Kozar, Joanna; Michalkiewicz, Beata; Wrobel, Rafal J.; Mozia, Sylwia; Pirog, Ewa; Usiak-Nejman, Ewelina K.; Serafin, Jaroslaw; Morawski, Antoni W.; Narkiewicz, Urszula

    2017-01-01

    A titanate-TiO_2 composite was obtained through hydrothermal treatment of TiO_2 in KOH solution. The presence of a titanate phase was confirmed by X-ray diffraction (XRD), whereas scanning electron microscopy (SEM) measurements showed the porous nano-rod structure of the material. The obtained nano-rods were treated with tetra-ethylene-pentamine (TEPA). Such synthesized sorbents were applied for CO_2 removal. The CO_2 capacity under a pressure of 1 bar and at 80 C was 0.47, 0.34, and 3.11 mmol.g"-"1 for the starting TiO_2, the titanate-TiO_2 composite and the TEPA-titanate-TiO_2 composite (27.4 wt% of TEPA), respectively. The experimental isotherms of CO_2 were analysed using the Langmuir, Freundlich, Sips, Toth, Unilan, Redlich-Peterson, Radke-Prausnitz, Dubinin-Radushkevich, Temkin and Pyzhev, and Jovanovich models. The error sums of squares (SSR) function was used to test the fit of the models. The analysis revealed that the Sips isotherm is the best-fitting model for the CO_2 adsorption on the starting TiO_2, whereas the Freundlich equation should be used to describe the CO_2 adsorption isotherm on the titanate-TiO_2 composite. The CO_2 adsorption on the TEPA-modified sorbents was proposed to be described using the Sips isotherm for physical sorption and the modified Sips model for chemical sorption. The calculated isosteric heat of adsorption was found to be E46 kJ mol"-"1, which is about two times higher than the heat of CO_2 absorption in liquid TEPA reported in the literature (i.e. E85 kJ.mol"-"1). Therefore, it was concluded that the TEPA-titanate-TiO_2 composite is an attractive alternative for liquid amines due to the lower energy of regeneration in the sorption-desorption process. The material was proved to be stable during multiple sorption-desorption cycles. Moreover, its thermal stability up to 150 C was confirmed by thermogravimetric analysis (TGA). All these features make it a promising alternative for sorbents based on liquid amines. (authors)

  5. Preparation and characterization of nanocomposite of graphitic carbon nitride and TiO2 as a porous support for nano catalyst for desulfurization process

    Directory of Open Access Journals (Sweden)

    Ezzat Rafiee

    2017-12-01

    Full Text Available A novel heterogeneous nanocatalyst H3PW12O40/TiO2/g-C3N4 (PW/TiO2/CN was successfully synthesized by immobilization of PW on TiO2/CN nanocomposite, and characterized by SEM, BET, FT-IR, XRD, EDX, TEM and ICP. Catalytic performance of the as-prepared catalyst was investigated for the selective oxidation of sulfides to sulfoxides and sulfones in the presence of H2O2 as oxidant with good conversion and high selectivity. The main factors influencing the ability for selective oxidation of sulfides were studied, including reaction temperature, amounts of the catalyst, H2O2 and type of the reaction solvent. Catalytic oxidation of the different model oils containing dibenzothiophene (DBT, benzothiophene (BT and thiophene (T into corresponding sulfone was also studied. Effects of different extractive solvents, aromatics, alkenes and nitrogen compounds on the oxidative desulfurization processes (ODS were also studied. In addition, reducing the level of sulfur content in real oil was investigated. The recyclability of the PW/TiO2/CN nanocatalyst for various cycles without a significant loss of activity was proved. The heterogeneity of the as-prepared catalyst was confirmed by leaching tests. Keywords: Graphitic carbon nitride, Extraction, Tetrabutyl titanate, Heteropoly acid, Oxidative desulfurization, Oil

  6. A Simple Surface Modification of NiO Cathode with TiO2 Nano-Particles for Molten Carbonate Fuel Cells (MCFCs)

    International Nuclear Information System (INIS)

    Choi, Hee Seon; Kim, Keon; Yi, Cheolwoo

    2014-01-01

    The TiO 2 -modified Ni powders, prepared by the simple method (ball-milling and subsequent annealing) without resorting to any complex coating process, eventually form nickel titanate passive layer at high temperature. It as good corrosion resistance in molten carbonates media and higher electrical conductivity at high temperature. In addition, the modified cathode increases the degree of lithiation during the operation of MCFC. These positive effects provide a decrease in the internal resistance and improve the cell performance. Results obtained from this study can be applied to develop the surface modification of cathode materials and the performance of molten carbonate fuel cells. Molten carbonate fuel cells (MCFCs) are efficient energy conversion devices to convert chemical energy into electrical energy through the electrochemical reaction. Because of a lot of advantages of MCFC operated at high temperature, many researchers have been trying to apply it to large-scaled power generations, marine boats, and so on. Among various cathode materials, nickel oxide, NiO, is the most widely used cathode for MCFCs due to its stability and high electrical conductivity, but the degradation of cathode material, so-called NiO dissolution, prevents a long-term operation of MCFC. In order to overcome the drawback, numerous studies have been performed. One of the most useful ways to enhance the surface property and maintain the bulk property of the host materials is the surface modification. The most common modification method is coating and these coating procedures which need some complicated steps with the use of organic materials, but it restricts the large-scale fabrication. In this study, to improve the electrochemical performance, we have prepared an alternative MCFC cathode material, TiO 2 -modified NiO, by simple method without resorting to any complex coating process. Results obtained in this study can provide an effective way to mass-produce the cathode materials

  7. Photocatalytic Degradation of Methylene Blue under UV Light Irradiation on Prepared Carbonaceous TiO2

    Directory of Open Access Journals (Sweden)

    Zatil Amali Che Ramli

    2014-01-01

    Full Text Available This study involves the investigation of altering the photocatalytic activity of TiO2 using composite materials. Three different forms of modified TiO2, namely, TiO2/activated carbon (AC, TiO2/carbon (C, and TiO2/PANi, were compared. The TiO2/carbon composite was obtained by pyrolysis of TiO2/PANi prepared by in situ polymerization method, while the TiO2/activated carbon (TiO2/AC was obtained after treating TiO2/carbon with 1.0 M KOH solution, followed by calcination at a temperature of 450°C. X-ray powder diffraction (XRD, transmission electron microscopy (TEM, Fourier transform infrared (FTIR, thermogravimetric analysis (TG-DTA, Brunauer-Emmet-Teller (BET, and UV-Vis spectroscopy were used to characterize and evaluate the prepared samples. The specific surface area was determined to be in the following order: TiO2/AC > TiO2/C > TiO2/PANi > TiO2 (179 > 134 > 54 > 9 m2 g−1. The evaluation of photocatalytic performance for the degradation of methylene blue under UV light irradiation was also of the same order, with 98 > 84.7 > 69% conversion rate, which is likely to be attributed to the porosity and synergistic effect in the prepared samples.

  8. The Implications of Fe2O3 and TiO2 Nanoparticles on the Removal of Trichloroethylene by Activated Carbon in the Presence and Absence of Humic Acid

    Science.gov (United States)

    The implications of Fe2O3 and TiO2 nanoparticles (NPs) on a granular activated carbon (GAC) adsorber and their impact on the removal of Trichloroethylene (TCE) were investigated in the presence of humic acid (HA). The surface charge of the GAC and NPs was obtained in the presence...

  9. Preparation, characterization and applications of novel carbon and nitrogen codoped TiO2 nanoparticles from annealing TiN under CO atmosphere

    International Nuclear Information System (INIS)

    Sun, Mingxuan; Song, Peng; Li, Jing; Cui, Xiaoli

    2013-01-01

    Graphical abstract: Carbon and nitrogen codoped TiO 2 nanoparticles were firstly fabricated by calcining TiN powder under CO atmosphere at different temperatures between 400 and 600 °C, both the improved photocatalytic activity for degradation of methylene blue and enhanced photovoltaic performance for dye sensitized solar cells were demonstrated. - Highlights: • CN-codoped TiO 2 nanoparticles were prepared by calcining TiN under CO atmosphere. • More visible light response was confirmed by UV–vis DRS and photocatalytic results. • Enhanced conversion efficiency was observed for the DSSCs from CN-TiO 2 photoanode. • CN-codoping played an important role to improve the photocatalytic performance. - Abstract: Carbon and nitrogen codoped titania (CN-TiO 2 ) nanoparticles were fabricated by calcining titanium nitride (TiN) nanoparticles under carbon monoxide (CO) atmosphere at four different temperatures in a range of 400–600 °C. The as-prepared samples were characterized with X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and X-ray photoelectron spectroscopy (XPS). Enhanced light absorption in both the UV and visible light region was observed for the resulted CN-TiO 2 nanoparticles in ultraviolet-visible diffuse reflectance spectroscopy (UV–vis DRS). Improved photocatalytic activity toward the degradation of methylene blue by the CN-TiO 2 nanoparticles was demonstrated under UV and visible light, respectively. The highest degradation rate was achieved for CN-TiO 2 nanoparticles (13%) compared to N-TiO 2 (10%) and the commercial P25 (5%) under visible light illumination for 40 min. Furthermore, the improved photocatalytic activity of CN-TiO 2 was also confirmed by the degradation of colorless resorcinol under UV–vis light irradiation. Dye-sensitized solar cells (DSSCs) were fabricated using P25, N-TiO 2 and CN-TiO 2 photoanodes, respectively. The highest conversion efficiency of 3.31% was achieved by the DSSCs based on the

  10. Interfacial enhancement of carbon fiber composites by growing TiO2 nanowires onto amine-based functionalized carbon fiber surface in supercritical water

    Science.gov (United States)

    Ma, Lichun; Li, Nan; Wu, Guangshun; Song, Guojun; Li, Xiaoru; Han, Ping; Wang, Gang; Huang, Yudong

    2018-03-01

    A novel amine-based functionalization method was developed to improve the interfacial adhesion between TiO2 NWs and CFs in supercritical water. The microstructure, morphology and mechanical properties of CFs were investigated. It was found that introducing hexamethylenetetramine (HMTA) dendrimers and branched polyethyleneimine (PEI) on CF could increase significantly the adhesion strength between CF and TiO2 NWs and their interfacial shear strength with epoxy resin, and the order is CF-PEI-TiO2 NWs > CF-HMTA-TiO2 NWs > CF-COOH-TiO2 NWs > CF-TiO2 NW. Meanwhile, the reinforcing mechanisms and interfacial failure modes have also been discussed. We believe that these effective methods may provide theoretical foundation for the preparation of high performance composite materials.

  11. 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%.

  12. Improved reaction kinetics and selectivity by the TiO2-embedded carbon nanofiber support for electro-oxidation of ethanol on PtRu nanoparticles

    Science.gov (United States)

    Nakagawa, Nobuyoshi; Ito, Yudai; Tsujiguchi, Takuya; Ishitobi, Hirokazu

    2014-02-01

    The electro-oxidation of ethanol by the catalyst of PtRu nanoparticles supported on a TiO2-embedded carbon nanofiber (PtRu/TECNF), which has recently been proposed by the authors as a highly active catalyst for methanol oxidation, is investigated by cyclic voltammetry using a glassy carbon electrode and by operating a direct ethanol fuel cell (DEFC) with the catalyst. The mass activity obtained from the cyclic voltammogram for the ethanol oxidation is compared to that for the methanol oxidation reported in our recent paper. The mass activity for the ethanol oxidation is comparable or slightly higher than that for the methanol oxidation, and the relationship between the TECNF composition, i.e., the Ti/C mass ratio, and the activity are also similar to that for the methanol oxidation. A DEFC fabricated with the PtRu/TECNF shows a higher power output compared to that with the commercial PtRu/C catalyst. An analysis of the reaction products by a simple two-step reaction model reveals that the PtRu/TECNF increases the rate constant for the reaction steps from ethanol to acetaldehyde and subsequently to CO2, but decreases that from acetaldehyde to acetic acid. This means that the PtRu/TECNF improves not only the kinetics, but also the selectivity to acetaldehyde.

  13. Improving the Power Conversion Efficiency of Carbon Quantum Dot-Sensitized Solar Cells by Growing the Dots on a TiO2 Photoanode In Situ

    Directory of Open Access Journals (Sweden)

    Quanxin Zhang

    2017-05-01

    Full Text Available Dye-sensitized solar cells (DSSCs are highly promising since they can potentially solve global energy issues. The development of new photosensitizers is the key to fully realizing perspectives proposed to DSSCs. Being cheap and nontoxic, carbon quantum dots (CQDs have emerged as attractive candidates for this purpose. However, current methodologies to build up CQD-sensitized solar cells (CQDSCs result in an imperfect apparatus with extremely low power conversion efficiencies (PCEs. Herein, we present a simple strategy of growing carbon quantum dots (CQDs onto TiO2 surfaces in situ. The CQDs/TiO2 hybridized photoanode was then used to construct solar cell with an improved PCE of 0.87%, which is higher than all of the reported CQDSCs adopting the simple post-adsorption method. This result indicates that an in situ growing strategy has great advantages in terms of optimizing the performance of CQDSCs. In addition, we have also found that the mechanisms dominating the performance of CQDSCs are different from those behind the solar cells using inorganic semiconductor quantum dots (ISQDs as the photosensitizers, which re-confirms the conclusion that the characteristics of CQDs differ from those of ISQDs.

  14. Effects of nitrogen and carbon doping on properties and photocatalytic activity of TiO2-In2O3 composite

    International Nuclear Information System (INIS)

    Wu, Chung-Hsin; Wu, Jui-Tai; Lai, Chih-Hao; Chung, Wei-Yang; Kuo, Chao-Yin; Hong, Pui-Kwan Andy

    2015-01-01

    TiO 2 -In 2 O 3 (Ti-In) was synthesized by the sol-gel method and the composite was further doped with nitrogen and carbon to create Ti-In-N and Ti-In-C, respectively. The dye C.I. Reactive Red 2 (RR2) was used a model compound to be subjected to various composites and measured for removal by photocatalytic degradation and adsorption. Ti-In-N possessed a larger mean diameter than Ti-In-C, while the latter possessed a greater anatase content and surface area than the former. After N or C doping, the spectra of corresponding Ti-In-N and Ti-In-C showed absorption edges at longer wavelengths than the parent Ti-In. Ti-N-O and Ti-O-C bonds were found in Ti-In-N and Ti-In-C composites, respectively. Ti-In-N was more effective for RR2 photodegradation than Ti-In-C, and the Ti-In-C removed more RR2 by adsorption than Ti-In-N

  15. Fabrication and Characterization of New Composite Tio2 Carbon Nanofiber Anodic Catalyst Support for Direct Methanol Fuel Cell via Electrospinning Method

    Science.gov (United States)

    Abdullah, N.; Kamarudin, S. K.; Shyuan, L. K.; Karim, N. A.

    2017-12-01

    Platinum (Pt) is the common catalyst used in a direct methanol fuel cell (DMFC). However, Pt can lead towards catalyst poisoning by carbonaceous species, thus reduces the performance of DMFC. Thus, this study focuses on the fabrication of a new composite TiO2 carbon nanofiber anodic catalyst support for direct methanol fuel cells (DMFCs) via electrospinning technique. The distance between the tip and the collector (DTC) and the flow rate were examined as influencing parameters in the electrospinning technique. To ensure that the best catalytic material is fabricated, the nanofiber underwent several characterizations and electrochemical tests, including FTIR, XRD, FESEM, TEM, and cyclic voltammetry. The results show that D18, fabricated with a flow rate of 0.1 mLhr-1 and DTC of 18 cm, is an ultrafine nanofiber with the smallest average diameter, 136.73 ± 39.56 nm. It presented the highest catalyst activity and electrochemical active surface area value as 274.72 mAmg-1 and 226.75m2 g-1 PtRu, respectively, compared with the other samples.

  16. Free-standing Hierarchical Porous Assemblies of Commercial TiO_2 Nanocrystals and Multi-walled Carbon Nanotubes as High-performance Anode Materials for Sodium Ion Batteries

    International Nuclear Information System (INIS)

    Liu, Xiong; Xu, Guobao; Xiao, Huaping; Wei, Xiaolin; Yang, Liwen

    2017-01-01

    Highlights: • Utilization of commercial nanomaterials to freestanding sodium electrode is demonstrated. • Free-standing electrodes composed of TiO_2 and MWCNTs are hierarchically porous. • Hierarchical porous architecture benefits charge transport and interfacial Na"+ adsorption. • Free-standing hierarchical porous electrodes exhibit superior Na storage performance. - Abstract: Freestanding hierarchical porous assemblies of commercial TiO_2 nanocrystals and multi-wall carbon nanotubes (MWCNTs) as electrode materials for sodium ion batteries (SIBs) are prepared via modified vacuum filtration, free-drying and annealing. Microstructure characterizations reveal that TiO_2 nanocrystals are confined in hierarchically porous, highly electrically conductive and mechanically robust MWCNTs networks with cross-linking of thermally-treated bovine serum albumin. The hierarchical porous architecture not only enables rapid charge transportation and sufficient interaction between electrode and electrolyte, but also guarantees abundant interfacial sites for Na"+ adsorption, which benefits substantial contribution from pseudocapacitive Na storage. When it is used directly as an anode for sodium-ion batteries, the prepared electrode delivers high specific capacity of 100 mA h g"−"1 at a current density of 3000 mA g"−"1, and 150 mA h g"−"1 after 500 cycles at a current density of 500 mA g"−"1. The low-cost TiO_2-based freestanding anode has large potential application in high-performance SIBs for portable, flexible and wearable electronics.

  17. Multi-Walled Carbon Nanotube Coating on Alkali Treated TiO2 Nanotubes Surface for Improvement of Biocompatibility

    Directory of Open Access Journals (Sweden)

    Jung-Eun Park

    2018-04-01

    Full Text Available The aim of this study is to enhance the bioactivity of pure titanium using multiple surface treatments for the application of the implant. To form the biofunctional multilayer coating on pure titanium, anodization was conducted to make titanium dioxide nanotubes, then multi-walled carbon nanotubes were coated using a dipping method after an alkali treatment. The surface characteristics at each step were analyzed using a field emission scanning electron microscope and X-ray diffractometer. The effect of the multilayer coating on the biocompatibility was identified using immersion and cytotoxicity tests. Better hydroxyapatite formation was observed on the surface of multilayer-coated pure titanium compared to non-treated pure titanium after immersion in the simulated body fluid. Improvement of biocompatibility by multiple surface treatments was identified through various cytotoxicity tests using osteoblast cells.

  18. Degradation of paracetamol by advance oxidation processes using modified reticulated vitreous carbon electrodes with TiO(2) and CuO/TiO(2)/Al(2)O(3).

    Science.gov (United States)

    Arredondo Valdez, H C; García Jiménez, G; Gutiérrez Granados, S; Ponce de León, C

    2012-11-01

    The degradation of paracetamol in aqueous solutions in the presence of hydrogen peroxide was carried out by photochemistry, electrolysis and photoelectrolysis using modified 100 pores per inch reticulated vitreous carbon electrodes. The electrodes were coated with catalysts such as TiO(2) and CuO/TiO(2)/Al(2)O(3) by electrophoresis followed by heat treatment. The results of the electrolysis with bare reticulated vitreous carbon electrodes show that 90% paracetamol degradation occurs in 4 h at 1.3 V vs. SCE, forming intermediates such as benzoquinone and carboxylic acids followed by their complete mineralisation. When the electrolysis was carried out with the modified electrodes such as TiO(2)/RVC, 90% degradation was achieved in 2 h while with CuO/TiO(2)/Al(2)O(3)/RVC, 98% degradation took only 1 h. The degradation was also carried out in the presence of UV reaching 95% degradation with TiO(2)/RVC/UV and 99% with CuO/TiO(2)/Al(2)O(3)/RVC/UV in 1 h. The reactions were followed by spectroscopy UV-Vis, HPLC and total organic carbon analysis. These studies show that the degradation of paracetamol follows a pseudo-first order reaction kinetics. Copyright © 2012 Elsevier Ltd. All rights reserved.

  19. Fabrication and CO2 separation performance of carbon membranes doped with TiO2 nanoparticles%纳米TiO2掺杂炭膜的制备及其CO2分离性能

    Institute of Scientific and Technical Information of China (English)

    王婵; 黄彦

    2014-01-01

    A TiO2 sol was prepared from tetrabutyltitanate using polyethylene glycol as a stabilizer, and this was homogeneously mixed with polyfurfuryl alcohol, dip-coated on a porous Al2 O3 substrate and carbonized at 700℃ for 4 h to produce TiO2-doped car-bon membranes. SEM, TEM, XRD and granulometry were used to characterize the membranes, and their permeation performance for CO2 , N2 and CH4 were tested. It was found that polyethylene glycol is effective in controlling the hydroxylation of the tetrabu-tyltitanate. This not only favored the formation of spherical TiO2 nanoparticles with a small size and narrow size distribution but also improved the homogeneity of the dispersion of the TiO2 nanoparticles in polyfurfuryl alcohol. The doping of the membranes with TiO2 nanoparticles greatly improved the CO2 permeance and permselectivity. The TiO2 doping helps to create diffusion paths, but it may also block the pores in the carbon matrix. Therefore, the CO2 permeance reached a maximum of 7. 0×10-8 mol·m-2·s-1·Pa-1 with a mass ratio of TiO2 sol to polyfurfuryl alcohol of 2, where the CO2/N2 and the CO2/CH4 selectivities were 34 and 64, respec-tively.%以钛酸丁酯为原料、聚乙二醇为稳定剂,采用溶胶-凝胶法制备含球形TiO2纳米粒子的溶胶,将其与碳前驱体聚糠醇均匀混合后涂敷于多孔Al2 O3基体表面,最后经炭化处理制得TiO2-C/Al2 O3复合膜。采用SEM、TEM、XRD、粒径分析等手段对样品进行表征,并测定炭膜对CO2、N2和CH4的渗透性能。结果表明,聚乙二醇能有效控制钛酸丁酯的水解,不仅有利于形成粒径小而均匀的球形纳米TiO2粒子,而且可促进TiO2粒子在聚糠醇中的均匀分散。 TiO2粒子的掺杂明显提高了炭膜的CO2渗透率及渗透选择性。其中,CO2渗透率、CO2/N2选择性和CO2/CH4选择性分别可达7.0´10-8 mol·m-2·s-1· Pa-1、34和64。 TiO2的掺杂有利于产生更多渗透通道,但也会阻断炭材料本

  20. PtNi alloy nanoparticles supported on carbon-doped TiO2 nanotube arrays for photo-assisted methanol oxidation

    International Nuclear Information System (INIS)

    He, Huichao; Xiao, Peng; Zhou, Ming; Liu, Feila; Yu, Shujuan; Qiao, Lei; Zhang, Yunhuai

    2013-01-01

    To develop anode catalysts for photo-assisted direct methanol fuel cell (PDMFC), carbon-doped TiO 2 nanotube arrays-supported PtNi alloy nanoparticles with different Pt/Ni atomic ratio (PtNi/C-TiO 2 NTs) prepared by pulsed electrodeposition method are evaluated as catalysts for photo-assisted methanol oxidation. The cyclic voltammetry (CV) and chronoamperometry results show that the PtNi/C-TiO 2 NTs prepared at t onPt :t onNi : = 10:7 (t on is the current-on time) with a Pt:Ni atomic ratio of 6.1:5.7 presents the highest catalytic activity for methanol oxidation both in the dark and under illumination. In addition, according to the results obtained from the CO stripping voltammetry and electrochemical impedance spectroscopy (EIS) tests, it was found that the light play an accelerative role in the oxidation of methanol on PtNi/C-TiO 2 NTs under illumination. The effect of illumination which enhancing the catalytic activity of PtNi/C-TiO 2 NTs are attributed to (1) methanol and the intermediates be oxidized directly on C-TiO 2 NTs for the light-induced catalytic effect; (2) more abundant oxygen-donating species be produced on C-TiO 2 NTs in the presence of light; (3) less CO ads adsorbing on catalysts due to the presence of stronger metal–support interactions between PtNi alloy nanoparticles and C-TiO 2 NTs under illumination

  1. Revealing the relationship between the photocatalytic property and structure characteristic of reduced TiO2 by hydrogen and carbon monoxide treatment.

    Science.gov (United States)

    Liu, Yunpeng; Li, Yuhang; Yang, Siyuan; Lin, Yuan; Zuo, Jianliang; Liang, Hong; Peng, Feng

    2018-06-04

    The hydrogenation (reduction) has been considered as an effective method to improve the photocatalytic activity of TiO2, however, the underlying relationship between structure and photocatalytic performance has still not been adequately unveiled so far. Herein, to obtain insight into the effect of structure on photocatalytic activity, two types of reduced TiO2 were prepared by CO (CO-TiO2) and H2 (H-TiO2), respectively. For H-TiO2, Ti-H bonds and oxygen vacancies are formed on the surface of H-TiO2, resulting in a more disorder surface lattice. However, for CO-TiO2, the more Ti-OH bonds are formed on the surface and the more bulk oxygen vacancies are introduced, the disorder layer of CO-TiO2 is relatively thin owing to the most of surface vacancies repaired by Ti-OH bonds. Under the simulated solar irradiation, the photocatalytic H2 evolution rate of CO-TiO2 reaches 7.17 mmol g-1 h-1, which is 4.14 and 1.50 times those of TiO2 and H-TiO2, respectively. The photocatalytic degradation rate constant of methyl orange on CO-TiO2 is 2.45 and 6.39 times those on H-TiO2 and TiO2. The superior photocatalytic activity of CO-TiO2 is attributed to the effective separation and transfer of the photo-generated electron-hole pairs, due to the synergistic effects of oxygen vacancies and surface Ti-OH bonds. This study reveals the relation between the photocatalytic property and structure, and provides a new method to prepare highly active TiO2 for H2 production and environmental treatment. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. On Sol–Gel Derived Au-Enriched TiO2 and TiO2-ZrO2 Photocatalysts and Their Investigation in Photocatalytic Reduction of Carbon Dioxide

    Czech Academy of Sciences Publication Activity Database

    Matějová, Lenka; Kočí, K.; Reli, M.; Čapek, L.; Matějka, V.; Šolcová, Olga; Obalová, L.

    2013-01-01

    Roč. 285, Part B (2013), s. 688-696 ISSN 0169-4332 Grant - others:MŠk(CZ) CZ.1.05/2.1.00/03.0069; MŠk(CZ) CZ.1.07/2.3.00/30.0016; MŠk(CZ) SP2013/77; MŠk(CZ) SP2013/41 Institutional support: RVO:67985858 Keywords : gold * titania-zirconia * carbon dioxide Subject RIV: CC - Organic Chemistry Impact factor: 2.538, year: 2013

  3. Reactivity of a reduced metal oxide surface: hydrogen, water and carbon monoxide adsorption on oxygen defective rutile TiO 2( 1 1 0 )

    Science.gov (United States)

    Menetrey, M.; Markovits, A.; Minot, C.

    2003-02-01

    The reactivity at reduced surface differs from that on the stoichiometric perfect surfaces. This does not originate uniquely from the modification of the coordination; electron count also is determining. The general trend is a decrease of the heat of adsorption on the metal cations. The reactivity decreases at sites in the vicinity of the defects due to the reduction induced by the O vacancies. At the defect site the decrease is less pronounced for H, H 2, CO and molecular H 2O. In the case of H 2O dissociative adsorption, the defect site is more reactive than the perfect surface. Thus, a hydration converting the defective-reduced TiO 2 to the hydrogenated non-defective-reduced surface is easy. The resulting structure possesses surface hydroxyl groups. It is probably the easiest way to form the hydrogenated non-defective surface. On TiO 2, the defective surface requires very anhydrous conditions.

  4. A flexible 3D nitrogen-doped carbon foam@CNTs hybrid hosting TiO2 nanoparticles as free-standing electrode for ultra-long cycling lithium-ion batteries

    Science.gov (United States)

    Yuan, Wei; Wang, Boya; Wu, Hao; Xiang, Mingwu; Wang, Qiong; Liu, Heng; Zhang, Yun; Liu, Huakun; Dou, Shixue

    2018-03-01

    Free-standing electrodes have stood out from the electrode pack, owing to their advantage of abandoning the conventional polymeric binder and conductive agent, thus increasing the specific capacity of lithium-ion batteries. Nevertheless, their practical application is hampered by inferior electrical conductivity and complex manufacturing process. To this end, we report here a facile approach to fabricate a flexible 3D N-doped carbon foam/carbon nanotubes (NCF@CNTs) hybrid to act as the current collector and host scaffold for TiO2 particles, which are integrated into a lightweight free-standing electrode (NCF@CNTs-TiO2). In the resulting architecture, ultra-fine TiO2 nanoparticles are homogeneously anchored in situ into the N-doped NCF@CNTs framework with macro- and meso-porous structure, wrapped by a dense CNT layer, cooperatively enhances the electrode flexibility and forms an interconnected conductive network for electron/ion transport. As a result, the as-prepared NCF@CNTs-TiO2 electrode exhibits excellent lithium storage performance with high specific capacity of 241 mAh g-1 at 1 C, superb rate capability of 145 mAh g-1 at 20 C, ultra-long cycling stability with an ultra-low capacity decay of 0.0037% per cycle over 2500 cycles, and excellent thermal stability with ∼94% capacity retention over 100 cycles at 55 °C.

  5. 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.

  6. 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.

  7. Enhanced conversion efficiency of dye-sensitized solar cells using a CNT-incorporated TiO2 slurry-based photoanode

    OpenAIRE

    Jiaoping Cai; Zexiang Chen; Jun Li; Yan Wang; Dong Xiang; Jijun Zhang; Hai Li

    2015-01-01

    A new titanium dioxide (TiO2) slurry formulation is herein reported for the fabrication of TiO2 photoanode for use in dye-sensitized solar cells (DSSCs). The prepared TiO2 photoanode featured a highly uniform mesoporous structure with well-dispersed TiO2 nanoparticles. The energy conversion efficiency of the resulting TiO2 slurry-based DSSC was ∼63% higher than that achieved by a DSSC prepared using a commercial TiO2 slurry. Subsequently, the incorporation of acid-treated multi-walled carbon ...

  8. Application of the Functional Theory in studying the adsorption of carbon monoxide on the TiO2 rutile surface of 110, defected surface and the surface modified by some metallic ions

    International Nuclear Information System (INIS)

    Le Kim Long; Phung Manh Quan; Tran Thi Thanh Van

    2012-01-01

    Density functional theory (DFT) is used to investigate properties of TiO 2 (110) surface with defects and metal-doped TiO 2 . The results of our calculations of structure of TiO 2 surface have been shown in good agreement with those of experiments and other ab-initio calculations. The differences of band structure between TiO 2 (110) and TiO 2 surface defected show that visible light can excite surface with defects easily. We also investigate density of states (DOS) of metal-doped surface (Li, Ca, Sc, V, Mo, Mn, Fe, Co, Ni) and find that the Mo-doped surface has very small band gap (∼ 0 eV). This surface may have higher photo-chemical activity in visible light. (author)

  9. TiO2@C Core-Shell Nanoparticles Formed by Polymeric Nano-Encapsulation

    Directory of Open Access Journals (Sweden)

    Mitra eVasei

    2014-07-01

    Full Text Available TiO2 semiconducting nanoparticles are known to be photocatalysts of moderate activity due to their high band-gap and high rate of electron-hole recombination. The formation of a shell of carbon around the core of TiO2, i.e. the formation of TiO2@C nanoparticles, is believed to partly alleviate these problems. It is usually achieved by a hydrothermal treatment in a presence of a sugar derivative. We present here a novel method for the formation of highly uniform C shell around TiO2 nanoparticles. For this purpose, TiO2 nanoparticles were dispersed in water using an oligomeric dispersant prepared by Reversible Addition-Fragmentation chain Transfer (RAFT polymerization. Then the nanoparticles were engaged into an emulsion polymerization of acrylonitrile, resulting in the formation of a shell of polyacrylonitrile (PAN around each TiO2 nanoparticles. Upon pyrolisis, the PAN was transformed into carbon, resulting in the formation of TiO2@C nanoparticles. The structure of the resulting particles was elucidated by X-Ray diffraction, FTIR, UV-VIS and Raman spectroscopy as well as TEM microscopy. Preliminary results about the use of the TiO2@C particles as photocatalysts for the splitting of water are presented. They indicate that the presence of the C shell is responsible for a significant enhancement of the photocurrent.

  10. Recovery TiO2 by leaching process of carbothermic reduced Kalimantan ilmenite

    Science.gov (United States)

    Wahyuningsih, S.; Sari, P. P.; Ramelan, A. H.

    2018-05-01

    Ilmenite naturally occurred in iron titanate (FeTiO3) minerals. The separation of natural ilmenite into TiO2 and Fe2O3 need to be explored to gain the high purity separation product. A new combination method named of carbothermic reduction, acidic-leaching and complexation by EDTA were proposed for separation TiO2 from Ilmenite. Roasting of ilmenite was carried out at 950 °C for 1 h by the addition of activated carbon with mass ratio of ilmenite : activated carbon =4:3. The carbothermic reduction was carried out to yield a high separation of initial content of ilmenite that will be easily to dissolve within hydrochloric acid solution in leaching process. The composition of ilmenite observed by X-Ray Fluoresences (XRF) changed after the carbothermic reduction process and the dominant content is TiO2 (57.56%). X-Ray Diffraction (XRD) of roasted ilmenite composed of decomposed product of ilmenite i.e. hematite (Fe2O3), TiO2 anatase, TiO2 rutile, and inorganic salt. The leaching of the roasted ilmenite has been done by sulphuric acid solution (6 M) to gain the titanyl sulphate solution. Separation of iron impurities of TiO2 gel from titanyl sulphate (TiOSO4) solution was conducted by complexation method using EDTA as a complexation agent. The characteristic of TiO2 obtained using XRD showed that TiO2 is anatase type and the percentage of TiO2 using XRF showed that TiO2 content of 86,03%.

  11. Microstructural Properties and HDS Activity of CoMo Catalysts Supported on Activated Carbon, Al2O3, ZrO2 and TiO2

    Czech Academy of Sciences Publication Activity Database

    Soukup, Karel; Procházka, Martin; Kaluža, Luděk

    2015-01-01

    Roč. 43, č. 2015 (2015), s. 841-846 ISSN 1974-9791. [International Conference on Chemical and Process Engineering - ICheaP12 /12./. Milano, 19.05.2015-22.05.2015] R&D Projects: GA ČR GAP106/11/0902 Institutional support: RVO:67985858 Keywords : CoMo catalysts * surface area * activated carbon Subject RIV: CF - Physical ; Theoretical Chemistry

  12. Novel TiO2/C nanocomposites: synthesis, characterization, and application as a photocatalyst for the degradation of organic pollutants.

    Science.gov (United States)

    da Costa, Elias; Zamora, Patricio P; Zarbin, Aldo J G

    2012-02-15

    Novel TiO(2)/carbon nanocomposites were prepared through the pyrolysis of TiO(2)/poly(furfuryl alcohol) hybrid materials, which were obtained by the sol-gel method, starting from titanium tetraisopropoxide (TTIP) and furfuryl alcohol (FA) precursors. Six different TiO(2)/C samples were prepared based on different TiO(2) nanoparticle sizes and TiO(2)/FA ratios. All of the samples were characterized using X-ray diffraction, infrared, and Raman spectroscopy. The results indicated effective FA polymerization onto the TiO(2) (anatase) nanoparticles, polymer conversion to disordered carbon following the pyrolysis, and a simultaneous TiO(2) anatase-rutile phase transition. The resulting TiO(2)/carbon composites were used as photocatalysts in the advanced oxidative process (AOP) for the degradation of reactive organic dyes in aqueous solution. The results indicate excellent photocatalytic performance (degradation of 99% of the dye after 60 min) with several advantages over traditional TiO(2)-based photocatalysts. Copyright © 2011 Elsevier Inc. All rights reserved.

  13. NOx photocatalytic degradation on gypsum plates modified by TiO2-N,C photocatalysts

    Directory of Open Access Journals (Sweden)

    Janus Magdalena

    2015-09-01

    Full Text Available In presented studies the photocatalytic decomposition of NOx on gypsum plates modified by TiO2-N,Cphotocatalysts were presented. The gypsum plates were obtained by addition of 10 or 20 wt.% of different types of titanium dioxide, such as: pure TiO2 and carbon and nitrogen co-modified TiO2 (TiO2-N,C to gypsum. TiO2-N,C photocatalysts were obtained by heating up the starting TiO2 (Grupa Azoty Zakłady Chemiczne Police S.A in the atmosphere of ammonia and carbon at the temperature: 100, 300 i 600ºC. Photocatalyst were characterized by FTIR/DRS, UVVis/DR, BET and XRD methods. Moreover the compressive strength tests of modified gypsum were also done. Photocatalytic activity of gypsum plates was done during NOx decomposition. The highest photocatalytic activity has gypsum with 20 wt.% addition of TiO2-N,C obtained at 300ºC.

  14. High performance sulfur, nitrogen and carbon doped mesoporous anatase–brookite TiO2 photocatalyst for the removal of microcystin-LR under visible light irradiation

    International Nuclear Information System (INIS)

    El-Sheikh, Said M.; Zhang, Geshan; El-Hosainy, Hamza M.; Ismail, Adel A.; O'Shea, Kevin E.; Falaras, Polycarpos; Kontos, Athanassios G.; Dionysiou, Dionysios D.

    2014-01-01

    Graphical abstract: - Highlights: • Synthesis of tailor-designed C, N and S doped titania anatase–brookite nano-heterojunction photocatalyst. • Microcystin-LR was completely removed in the presence of doped sample under visible light. • The MC-LR degradation rate achieved by the doped sample was much better than that of un-doped sample under visible light. - Abstract: Carbon, nitrogen and sulfur (C, N and S) doped mesoporous anatase–brookite nano-heterojunction titania photocatalysts have been synthesized through a simple sol–gel method in the presence of triblock copolymer Pluronic P123. XRD and Raman spectra revealed the formation of anatase and brookite mixed phases. XPS spectra indicated the presence of C, N and S dopants. The TEM images demonstrated the formation of almost monodisperse titania nanoparticles with particle sizes of approximately 10 nm. N 2 isotherm measurements confirmed that both doped and undoped titania anatase–brookite materials have mesoporous structure. The photocatalytic degradation of the cyanotoxin microcystin-LR (MC-LR) has been investigated using these novel nanomaterials under visible light illumination. The photocatalytic efficiency of the mesoporous titania anatase–brookite photocatalyst dramatically increased with the addition of the C, N and S non-metal, achieving complete degradation (∼100%) of MC-LR. The results demonstrate the advantages of the synthetic approach and the great potential of the visible light activated C, N, and S doped titania photocatalysts for the treatment of organic micropollutants in contaminated waters under visible light

  15. 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.

  16. Preparation and enhanced photocatalytic activity of carbon nitride/titania(001 vs 101 facets)/reduced graphene oxide (g-C3N4/TiO2/rGO) hybrids under visible light

    Science.gov (United States)

    Huang, Meina; Yu, Jianhua; Hu, Qun; Su, Wenli; Fan, Minguang; Li, Bin; Dong, Lihui

    2016-12-01

    Herein, a novel photocatalyst, anatase TiO2 nanoparticles with both exposed (101) and (001) facets synchronously incorporated with g-C3N4 and graphene, was successfully prepared via a simple one-step solvothermal route. The morphology and structure of as-prepared composites were confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS). Efficiency of the prepared samples was investigated by monitoring the degradation of Methyl Orange (MO), Rhodamine B (RhB) and phenol under visible light irradiation. Improved photocatalytic activity in g-C3N4/TiO2/rGO is observed owing to higher specific surface area and enhanced visible light absorption capability. Most importantly, the in situ g-C3N4 and rGO doping might enhance the interaction among g-C3N4, TiO2 (001 vs 101) and rGO, which generates more synergistic heteroconjunctions in g-C3N4/TiO2/rGO facilitating a fast electron transfer at the interface among them. This synergistic approach could prove useful for the design and development of other visible light active photocatalysts with high chemical stability.

  17. Effect of sunlight irradiation on photocatalytic pyrene degradation in contaminated soils by micro-nano size TiO2

    International Nuclear Information System (INIS)

    Chang Chien, S.W.; Chang, C.H.; Chen, S.H.; Wang, M.C.; Madhava Rao, M.; Satya Veni, S.

    2011-01-01

    The enhanced catalytic pyrene degradation in quartz sand and alluvial and red soils by micro-nano size TiO 2 in the presence and absence of sunlight was investigated. The results showed that the synergistic effect of sunlight irradiation and TiO 2 was more efficient on pyrene degradation in quartz sand and red and alluvial soils than the corresponding reaction system without sunlight irradiation. In the presence of sunlight irradiation, the photooxidation (without TiO 2 ) of pyrene was very pronounced in alluvial and red soils and especially in quartz sand. However, in the absence of sunlight irradiation, the catalytic pyrene degradation by TiO 2 and the photooxidation (without TiO 2 ) of pyrene were almost nil. This implicates that ultra-violet (UV) wavelength range of sunlight plays an important role in TiO 2 -enhanced photocatalytic pyrene degradation and in photooxidation (without TiO 2 ) of pyrene. The percentages of photocatalytic pyrene degradation by TiO 2 in quartz sand, alluvial and red soils under sunlight irradiation were 78.3, 23.4, and 31.8%, respectively, at 5 h reaction period with a 5% (w/w) dose of the amended catalyst. The sequence of TiO 2 -enhanced catalytic pyrene degradation in quartz sand and alluvial and red soils was quartz sand > red soil > alluvial soil, due to different texture and total organic carbon (TOC) contents of the quartz sand and other two soils. The differential Fourier transform infrared (FT-IR) spectra of degraded pyrene in alluvial soil corroborate that TiO 2 -enhanced photocatalytic degradation rate of degraded pyrene was much greater than photooxidation (without TiO 2 ) rate of degraded pyrene. Based on the data obtained, the importance for the application of TiO 2 -enhanced photocatalytic pyrene degradation and associated organic contaminants in contaminated soils was elucidated. - Highlights: → Synergistic effect of sunlight irradiation and TiO 2 promoted degradation of pyrene. → Micro-nano size TiO 2 enhanced

  18. 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.

  19. Two-dimensional TiO_2-based nanosheets co-modified by surface-enriched carbon dots and Gd_2O_3 nanoparticles for efficient visible-light-driven photocatalysis

    International Nuclear Information System (INIS)

    Lu, Dingze; Fang, Pengfei; Ding, Junqian; Yang, Minchen; Cao, Yufei; Zhou, Yawei; Peng, Kui; Kondamareddy, Kiran Kumar; Liu, Min

    2017-01-01

    Highlights: • Gd-C-TNSs with high stability and recycle usability were prepared by two-pot method. • Gd_2O_3 loading results in the structure changes of TNSs and increase of the Ti"3"+ ions. • Modified CDs leads to obvious increase of optical absorption ability and red shift. • Appropriate amount of Gd_2O_3 nanoparticles and CDs improve the separation of charges. • Gd-C-TNSs exhibit excellent synergistic photocatalytic activity for Cr(VI) and RhB. - Abstract: Two-dimensional TiO_2-based nanosheets (TNSs) co-modified by surface-enriched carbon dots (CDs) and Gd_2O_3 nanoparticles: (Gd-C-TNSs), capable of exhibiting visible-light-driven photo catalysis were synthesized using a two-pot hydrothermal route. The samples had a sheet-like structure, thickness of approximately 3.6 nm, large specific surface area of 240–350 cm"2/g. The CDs (2–3 nm) and Gd_2O_3 nanoparticles (1–2 nm) were highly dispersed over the surface of the nanosheets. The co-modification by Gd_2O_3 nanoparticles and CDs influenced the crystallinity, crystal structure, and surface area of the TNSs, and improved the visible-light absorption. Surface photocurrent and fluorescence spectral studies revealed that the photo-generated charge carrier separation efficiency could be improved by an appropriate amount of modification. A very high efficiency was obtained using 0.5 at% Gd/Ti and 3.0 g/L of CDs. The visible-light-induced photocatalytic activity is enhanced under the isolated Cr(VI) system, isolated Rhodamin B (RhB) system, and the synergism between RhB degradation and Cr(VI) reduction for the Gd-C-TNSs photocatalysts. Initially, the photocatalytic activity gradually increased with an increase in the amount of CDs, and then decreased after attaining a maximum, in the case where 0.5 at% Gd/Ti and 3.0 g/L of CDs were used. The enhancement in the photocatalytic activity was attributed to the synergetic effect of the Gd_2O_3 nanoparticles, TNSs, and CDs in the Gd-C-TNSs composites. The

  20. 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.

  1. Adsorption performance of titanium dioxide (TiO2) coated air filters for volatile organic compounds.

    Science.gov (United States)

    Zhong, Lexuan; Lee, Chang-Seo; Haghighat, Fariborz

    2012-12-01

    The photocatalytic oxidation (PCO) technology as an alternative method for air purification has been studied for decades and a variety of PCO models indicate that the adsorption of reactants on the catalyst surface is one of the major physical and chemical processes occurring at a heterogeneous photocatalytic reaction. However, limited study explored the adsorption effect of a photocatalyst. This study carried out a systematic evaluation of adsorption performance of titanium dioxide (TiO(2)) coated fiberglass fibers (FGFs), TiO(2) coated carbon cloth fibers (CCFs), and original CCFs air filters at various relative humidity conditions for nine volatile organic compounds. TiO(2)/FGFs, TiO(2)/CCFs, and CCFs were characterized by SEM for morphology and N(2) adsorption isotherm for BET surface area and pore structure. A bench-scale adsorption test setup was constructed and adsorption tests were performed at various relative humidity conditions and four different injected concentrations for each compound. The isothermal adsorption curves at low concentration levels were obtained and they were well described by Langmuir isotherm model. It was noticed that there were significant differences between the adsorption behaviors and photocatalytic activities of TiO(2)/FGFs and TiO(2)/CCFs. It was concluded that adsorption performance is closely related to the characteristics of substrates and therefore, the development of a substrate with high adsorption ability is a promising trend for improving the performance of the UV-PCO technology. Copyright © 2012 Elsevier B.V. All rights reserved.

  2. Phenol degradation by TiO2 photocatalysts combined with different pulsed discharge systems.

    Science.gov (United States)

    Zhang, Yi; Lu, Jiani; Wang, Xiaoping; Xin, Qing; Cong, Yanqing; Wang, Qi; Li, Chunjuan

    2013-11-01

    Films of TiO2 nanotubes distributed over the inner surface of a discharge reactor cylinder (CTD) or adhered to a stainless steel electrode surface (PTD) in a discharge reactor were compared with a single-discharge (SD) system to investigate their efficiencies in phenol degradation. Morphology studies indicated that the TiO2 film was destroyed in the PTD system, but that there was no change in the CTD system after discharge. X-ray diffraction results revealed that the anatase phase of the original sample was preserved in the CTD system, but that an anatase-to-rutile phase transformation occurred in the PTD system after discharge. The highest efficiencies of phenol degradation and total organic carbon (TOC) mineralization were observed in the CTD system, and there was no decrease in phenol degradation efficiency upon reuse of a TiO2 film, indicating high catalysis activity and stability of the TiO2 photocatalysts in the combined treatment. TiO2 photocatalysts favored the formation of hydrogen peroxide and disfavored the formation of ozone. A greater degree of oxidation of intermediates and higher energy efficiency in phenol oxidation were observed with the TiO2-plasma systems, especially in the CTD system, compared to those with the SD system. Copyright © 2013 Elsevier Inc. All rights reserved.

  3. 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.

  4. 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.

  5. 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

  6. 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)

  7. 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.

  8. 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

  9. Solar photocatalytic degradation of isoproturon over TiO2/H-MOR composite systems

    International Nuclear Information System (INIS)

    Sharma, Mangalampalli V. Phanikrishna; Durgakumari, Valluri; Subrahmanyam, Machiraju

    2008-01-01

    The photocatalytic degradation and mineralization of isoproturon herbicide was investigated in aqueous solution containing TiO 2 over H-mordenite (H-MOR) photocatalysts under solar light. The catalysts are characterized by X-ray diffraction (XRD), UV-Vis diffused reflectance spectra (UV-Vis DRS), Fourier transform-infra red spectra (FT-IR) and scanning electron microscopy (SEM) techniques. The effect of TiO 2 , H-MOR support and different wt% of TiO 2 over the support on the photocatalytic degradation and influence of parameters such as TiO 2 loading, catalyst amount, pH and initial concentration of isoproturon on degradation are evaluated. 15 wt% TiO 2 /H-MOR composite is found to be optimum. The degradation reaction follows pseudo-first order kinetics and is discussed in terms of Langmuir-Hinshelwood (L-H) kinetic model. The extent of isoproturon mineralization studied with chemical oxygen demand (COD) and total organic carbon (TOC) measurements and ∼80% mineralization occurred in 5 h. A plausible mechanism is proposed based on the intermediates identified by liquid chromatography-mass spectroscopy (LC-MS)

  10. Solar photocatalytic degradation of isoproturon over TiO2/H-MOR composite systems.

    Science.gov (United States)

    Sharma, Mangalampalli V Phanikrishna; Durgakumari, Valluri; Subrahmanyam, Machiraju

    2008-12-30

    The photocatalytic degradation and mineralization of isoproturon herbicide was investigated in aqueous solution containing TiO2 over H-mordenite (H-MOR) photocatalysts under solar light. The catalysts are characterized by X-ray diffraction (XRD), UV-Vis diffused reflectance spectra (UV-Vis DRS), Fourier transform-infra red spectra (FT-IR) and scanning electron microscopy (SEM) techniques. The effect of TiO2, H-MOR support and different wt% of TiO2 over the support on the photocatalytic degradation and influence of parameters such as TiO2 loading, catalyst amount, pH and initial concentration of isoproturon on degradation are evaluated. 15wt% TiO2/H-MOR composite is found to be optimum. The degradation reaction follows pseudo-first order kinetics and is discussed in terms of Langmuir-Hinshelwood (L-H) kinetic model. The extent of isoproturon mineralization studied with chemical oxygen demand (COD) and total organic carbon (TOC) measurements and approximately 80% mineralization occurred in 5h. A plausible mechanism is proposed based on the intermediates identified by liquid chromatography-mass spectroscopy (LC-MS).

  11. Mesoporous TiO2 : an alternative material for PEM fuel cells catalyst support

    Energy Technology Data Exchange (ETDEWEB)

    Do, T.B. [Michigan Univ., Ann Arbor, MI (United States). Dept. of Materials Science; Ruthkosky, M.; Cai, M. [General Motors, Warren, MI (United States). Research and Development Center

    2008-07-01

    This paper discussed the feasibility of using an alternative catalyst support material to replace carbon in proton exchange membrane (PEM) fuel cells. The alternative catalyst support material requires a high surface area with a large porosity but must have comparable conductivity with carbon. A mesoporous titanium oxide (TiO2) material produced by coprecipitation was introduced. The conductivity of the material is about one order of that of carbon. The 8 mole per cent Nb-doped TiO2 was formed and deposited on the surface of a nano polystyrene (PS) template via the hydrolysis of a co-solution of Ti(OC4H9)4 and Nb(OC2H5)5. The removal of PS by heat treatment produced porous structure of TiO2 with the appearance of 3 different pore types, notably open pore, ink-pot pores and closed pores. TiO2 formed from the rutile phase, allowing a lower activation temperature at 850 degrees C in a hydrogen atmosphere. The pore structures were retained after this heat treatment. The BET surface area was 116 m{sup 2}/g, porosity was 22 per cent and the average pore size was 159 angstrom. The conductivity improved considerably from almost non-conductive to one order of that of carbon.

  12. 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...

  13. Sol–gel synthesis of highly TiO2 aerogel photocatalyst via high temperature supercritical drying

    Directory of Open Access Journals (Sweden)

    Rebah Moussaoui

    2017-09-01

    Full Text Available Nanocrystalline powders of TiO2 xerogel and aerogel were prepared by using acid-modified sol–gel approach. For TiO2 aerogel material (TA, the solvent was high temperature supercritically extracted at 300 °C and 100 bars. However, the TiO2 xerogel material (TX was dried at 200 °C and ambient pressure. The effects of the drying processes on the crystalline structure, phase transformation and grain growth were determined by Raman spectroscopy, SAED and X-ray diffraction (XRD analyses using Rietveld refinement method. The TiO2 aerogel was composed of anatase crystalline structure. The TiO2 xerogel material was composed of anatase, brookite and small amount of amorphous phase with anatase as dominant phase. The TX sample still contains a relatively high concentration of carbon than that of TA, indicating the amorphous character of TiO2 xerogel. These materials were applied as catalyst for the degradation of indigo carmine in aqueous medium. Photo-degradation ability of TA and TX was compared to the TiO2 commercial Degussa P25. The photo-catalytic results showed that the degradation efficiency was in the order TA > P25 > TX. The photo-degradation of indigo carmine followed pseudo first order reaction kinetics.

  14. Photodegradation of oxytetracycline in aqueous by 5A and 13X loaded with TiO2 under UV irradiation

    International Nuclear Information System (INIS)

    Zhao Chun; Deng Huiping; Li Yuan; Liu Zhenzhong

    2010-01-01

    The photocatalysis degradation, mineralization and detoxification of oxytetracycline (OTC) in aqueous were investigated by 5A and 13X zeolite with nano-TiO 2 loaded under UV light. The composite photocatalysts are characterized by X-ray diffraction (XRD) and field emission scanning (FESEM) technologies. The adsorption isotherms of OTC by 5A and 13X with different pH are evaluated. The results show that 654 and 1497 mg/g OTC of saturation adsorption capacity is reached by 5A and 13X at pH 7, respectively. Then the effect of TiO 2 with 5A and 13X support and different wt% of TiO 2 over the support on the resultant OTC removal, net photocatalytic degradation and influence factors such as TiO 2 loading, initial pH, concentration of OTC and adding anion on degradation are investigated. The 15 wt% TiO 2 /5A and 10 wt% TiO 2 /13X photocatalysts are found optimum for OTC removal and degradation in aqueous. The mineralization was measured by total organic carbon (TOC) while combined toxicity change during OTC degradation was tested with standardized bioluminescence assay of inhibition rate on Vibrio qinghaiensis sp.-Q67 (Q67). The results suggest that TiO 2 /5A and TiO 2 /13X composite systems are effective photocatalysts for treatment of OTC in aqueous.

  15. Reaction of silanes in supercritical CO2 with TiO2 and Al2O3.

    Science.gov (United States)

    Gu, Wei; Tripp, Carl P

    2006-06-20

    Infrared spectroscopy was used to investigate the reaction of silanes with TiO2 and Al2O3 using supercritical CO2 (Sc-CO2) as a solvent. It was found that contact of Sc-CO2 with TiO2 leads to partial removal of the water layer and to the formation of carbonate, bicarbonate, and carboxylate species on the surface. Although these carbonate species are weakly bound to the TiO2 surface and can be removed by a N2 purge, they poison the surface, resulting in a lower level of reaction of silanes with TiO2. Specifically, the amount of hexamethyldisilazane adsorbed on TiO2 is about 10% of the value obtained when the reaction is performed from the gas phase. This is not unique to TiO2, as the formation of carbonate species also occurs upon contact of Al2O3 with Sc-CO2 and this leads to a lower level of reaction with hexamethyldisilazane. This is in contrast to reactions of silanes on SiO2 where Sc-CO2 has several advantages over conventional gaseous or nonaqueous methods. As a result, caution needs to be applied when using Sc-CO2 as a solvent for silanization reactions on oxides other than SiO2.

  16. Evaluation of the content of TiO2 nanoparticles in the coatings of chewing gums.

    Science.gov (United States)

    Dudefoi, William; Terrisse, Hélène; Popa, Aurelian Florin; Gautron, Eric; Humbert, Bernard; Ropers, Marie-Hélène

    2018-02-01

    Titanium dioxide is a metal oxide used as a white pigment in many food categories, including confectionery. Due to differences in the mass fraction of nanoparticles contained in TiO 2 , the estimated intakes of TiO 2 nanoparticles differ by a factor of 10 in the literature. To resolve this problem, a better estimation of the mass of nanoparticles present in food products is needed. In this study, we focused our efforts on chewing gum, which is one of the food products contributing most to the intake of TiO 2 . The coatings of four kinds of chewing gum, where the presence of TiO 2 was confirmed by Raman spectroscopy, were extracted in aqueous phases. The extracts were analysed by transmission electron microscopy (TEM), X-ray diffraction, Fourier Transform Raman spectroscopy, and inductively coupled plasma atomic emission spectroscopy (ICP-AES) to establish their chemical composition, crystallinity and size distribution. The coatings of the four chewing gums differ chemically from each other, and more specifically the amount of TiO 2 varies from one coating to another. TiO 2 particles constitute the entire coating of some chewing gums, whereas for others, TiO 2 particles are embedded in an organic matrix and/or mixed with minerals like calcium carbonate, talc, or magnesium silicate. We found 1.1 ± 0.3 to 17.3 ± 0.9 mg TiO 2 particles per piece of chewing gum, with a mean diameter of 135 ± 42 nm. TiO 2 nanoparticles account for 19 ± 4% of all particles, which represents a mass fraction of 4.2 ± 0.1% on average. The intake of nanoparticles is thus highly dependent on the kind of chewing gum, with an estimated range extending from 0.04 ± 0.01 to 0.81 ± 0.04 mg of nano-TiO 2 per piece of chewing gum. These data should serve to refine the exposure scenario.

  17. 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.

  18. Enhanced conversion efficiency of dye-sensitized solar cells using a CNT-incorporated TiO2 slurry-based photoanode

    Directory of Open Access Journals (Sweden)

    Jiaoping Cai

    2015-02-01

    Full Text Available A new titanium dioxide (TiO2 slurry formulation is herein reported for the fabrication of TiO2 photoanode for use in dye-sensitized solar cells (DSSCs. The prepared TiO2 photoanode featured a highly uniform mesoporous structure with well-dispersed TiO2 nanoparticles. The energy conversion efficiency of the resulting TiO2 slurry-based DSSC was ∼63% higher than that achieved by a DSSC prepared using a commercial TiO2 slurry. Subsequently, the incorporation of acid-treated multi-walled carbon nanotubes (CNTs into the TiO2 slurry was examined. More specifically, the effect of varying the concentration of the CNTs in this slurry on the performance of the resulting DSSCs was studied. The chemical state of the CNTs-incorporated TiO2 photoanode was investigated by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. A high energy conversion efficiency of 6.23% was obtained at an optimum CNT concentration of ∼0.06 wt.%. The obtained efficiency corresponds to a 63% enhancement when compared with that obtained from a DSSC based on a commercial TiO2 slurry. The higher efficiency was attributed to the improvement in the collection and transport of excited electrons in the presence of the CNTs.

  19. Enhanced conversion efficiency of dye-sensitized solar cells using a CNT-incorporated TiO2 slurry-based photoanode

    Science.gov (United States)

    Cai, Jiaoping; Chen, Zexiang; Li, Jun; Wang, Yan; Xiang, Dong; Zhang, Jijun; Li, Hai

    2015-02-01

    A new titanium dioxide (TiO2) slurry formulation is herein reported for the fabrication of TiO2 photoanode for use in dye-sensitized solar cells (DSSCs). The prepared TiO2 photoanode featured a highly uniform mesoporous structure with well-dispersed TiO2 nanoparticles. The energy conversion efficiency of the resulting TiO2 slurry-based DSSC was ˜63% higher than that achieved by a DSSC prepared using a commercial TiO2 slurry. Subsequently, the incorporation of acid-treated multi-walled carbon nanotubes (CNTs) into the TiO2 slurry was examined. More specifically, the effect of varying the concentration of the CNTs in this slurry on the performance of the resulting DSSCs was studied. The chemical state of the CNTs-incorporated TiO2 photoanode was investigated by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. A high energy conversion efficiency of 6.23% was obtained at an optimum CNT concentration of ˜0.06 wt.%. The obtained efficiency corresponds to a 63% enhancement when compared with that obtained from a DSSC based on a commercial TiO2 slurry. The higher efficiency was attributed to the improvement in the collection and transport of excited electrons in the presence of the CNTs.

  20. 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.%.

  1. Photocatalytic activity of Sulfer-doped TiO2 fiber under visible light illumination (Joint research)

    International Nuclear Information System (INIS)

    Takeyama, Akinori; Yamamoto, Shunya; Yoshikawa, Masahito; Hasegawa, Yoshio; Awatsu, Satoshi

    2007-03-01

    The Sol-Gel derived precursor fiber was annealed under hydrogen disulfeid (H 2 S) following oxygen atmosphere, Sulfur-doped TiO 2 fiber was obtained. Crystal structure of the fiber was identified as anatase phase of TiO 2 . The energy band gap of the fiber was narrower by about 0.06 eV than that of anatase, which showed that it could absorb visible light. The fiber contains about 0.58 atomic % of Sulfur, and they located at the oxygen lattice site of TiO 2 . Under visible light illumination, the fiber degraded Trichloroethylen (TCE) and produced carbon dioxide (CO 2 ). This shows Sulfur-doped TiO 2 fiber has the photocatalytic activity under visible light illumination. (author)

  2. 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.

  3. 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.

  4. 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% activity was protected after 11 cycles for method A and 16 cycles for method B

  5. Suggestion for the detection of TiO2 in interstellar medium

    Science.gov (United States)

    Kumar Sharma, Mohit; Sharma, Monika; Chandra, Suresh

    2017-09-01

    Since all the carbon in oxygen-rich stars is locked into carbon monoxide (CO), how the formation of dust takes place in their environment is a matter of great interest. Being a refractory species, the titanium dioxide (TiO2) is thought to play important role in the dust-condensation sequence. The TiO2 is detected in the environment of red supergiant VY Canis Majoris through sub-millimeter wavelengths. All these lines are between the levels lying at high energies for which large kinetic temperature in the region is required. Based on the detailed study of transfer of radiation, we propose for the identification of TiO2 through its transitions between low lying levels. Using spectroscopic data, we have calculated energies of 100 rotational levels of para-TiO2 (up to 82 cm^{-1}) and the Einstein A-coefficients for radiative transitions between the levels. These Einstein A-coefficients along with the scaled values of collisional rate coefficients, we have solved a set of 100 statistical equilibrium equations coupled with 436 equations of radiative transfer. We have found 9 transitions having anomalous absorption and 6 transitions showing emission features. These transitions may help in identification of TiO2 in a cosmic object.

  6. 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...

  7. 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...

  8. 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.

  9. Facile synthesis and characterization of N-doped TiO2/C nanocomposites with enhanced visible-light photocatalytic performance

    Science.gov (United States)

    Jia, Tiekun; Fu, Fang; Yu, Dongsheng; Cao, Jianliang; Sun, Guang

    2018-02-01

    Ultrafine anatase N-doped TiO2 nanocrystals modified with carbon (denoted as N-doped TiO2/C) were successfully prepared via a facile and low-cost approach, using titanium tetrachloride, aqueous ammonia and urea as starting materials. The phase composition, surface chemical composition, morphological structure, electronic and optical properties of the as-prepared photocatalysts were well characterized and analyzed. On the basis of Raman spectral characterization combining with the results of X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscopy (HRTEM), it could be concluded that N dopant ions were successfully introduced into TiO2 crystal lattice and carbon species were modified on the surface or between the nanoparticles to form N-doped TiO2/C nanocomposites. Compared with that of bare TiO2, the adsorption band edge of N-doped TiO2/C nanocomposites were found to have an evident red-shift toward visible light region, implying that the bandgap of N-doped TiO2/C nanocomposites is narrowed and the visible light absorption capacity is significantly enhanced due to N doping and carbon modification. The photoactivity of the as-prepared photocatalytsts was tested by the degradation of Rhodamine B (RhB) under visible light (λ > 420 nm), and the results showed that the N-doped TiO2/C nanocomposites exhibited much higher photodegradation rate than pure TiO2 and N-doped TiO2, which was mainly attributed to the synergistic effect of the enhanced light harvesting, augmented catalytic active sites and efficient separation of photogenerated electron-hole pairs.

  10. Effect of sintering temperatures and screen printing types on TiO2 layers in DSSC applications

    Science.gov (United States)

    Supriyanto, Agus; Furqoni, Lutfi; Nurosyid, Fahru; Hidayat, Jojo; Suryana, Risa

    2016-03-01

    Dye-Sensitized Solar Cell (DSSC) is a candidate solar cell, which has a big potential in the future due to its eco-friendly material. This research is conducted to study the effect of sintering temperature and the type of screen-printing toward the characteristics of TiO2 layer as a working electrode in DSSC. TiO2 layers were fabricated using a screen-printing method with a mesh size of T-49, T-55, and T-61. TiO2 layers were sintered at temperatures of 600°C and 650°C for 60 min. DSSC structure was composed of TiO2 as semiconductors, ruthenium complex as dyes, and carbon as counter electrodes. The morphology of TiO2 layer was observed by using Nikon E2 Digital Camera Microscopy. The efficiencies of DSSC were calculated from the I-V curves. The highest efficiency is 0.015% at TiO2 layer fabricated with screen type T-61 and at a sintering temperature of 650°C.

  11. Effect of sintering temperatures and screen printing types on TiO_2 layers in DSSC applications

    International Nuclear Information System (INIS)

    Supriyanto, Agus; Furqoni, Lutfi; Nurosyid, Fahru; Suryana, Risa; Hidayat, Jojo

    2016-01-01

    Dye-Sensitized Solar Cell (DSSC) is a candidate solar cell, which has a big potential in the future due to its eco-friendly material. This research is conducted to study the effect of sintering temperature and the type of screen-printing toward the characteristics of TiO_2 layer as a working electrode in DSSC. TiO_2 layers were fabricated using a screen-printing method with a mesh size of T-49, T-55, and T-61. TiO_2 layers were sintered at temperatures of 600°C and 650°C for 60 min. DSSC structure was composed of TiO_2 as semiconductors, ruthenium complex as dyes, and carbon as counter electrodes. The morphology of TiO_2 layer was observed by using Nikon E2 Digital Camera Microscopy. The efficiencies of DSSC were calculated from the I-V curves. The highest efficiency is 0.015% at TiO_2 layer fabricated with screen type T-61 and at a sintering temperature of 650°C.

  12. Water on Graphene-Coated TiO2: Role of Atomic Vacancies

    Science.gov (United States)

    2018-01-01

    Beyond two-dimensional (2D) materials, interfaces between 2D materials and underlying supports or 2D-coated metal or metal oxide nanoparticles exhibit excellent properties and promising applications. The hybrid interface between graphene and anatase TiO2 shows great importance in photocatalytic, catalytic, and nanomedical applications due to the excellent and complementary properties of the two materials. Water, as a ubiquitous and essential element in practical conditions and in the human body, plays a significant role in the applications of graphene/TiO2 composites for both electronic devices and nanomedicine. Carbon vacancies, as common defects in chemically prepared graphene, also need to be considered for the application of graphene-based materials. Therefore, the behavior of water on top and at the interface of defective graphene on anatase TiO2 surface was systematically investigated by dispersion-corrected hybrid density functional calculations. The presence of the substrate only slightly enhances the on-top adsorption and reduces the on-top dissociation of water on defective graphene. However, at the interface, dissociated water is largely preferred compared with undissociated water on bare TiO2 surface, showing a prominent cover effect. Reduced TiO2 may further induce oxygen diffusion into the bulk. Our results are helpful to understand how the presence of water in the surrounding environment affects structural and electronic properties of the graphene/TiO2 interface and thus its application in photocatalysis, electronic devices, and nanomedicine. PMID:29368503

  13. 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.

  14. Taking a fresh look at optical crowding of TiO2: the role of nanocarbonate as synergistic optical extender

    Science.gov (United States)

    Ridgway, Cathy J.; Gane, Patrick A. C.

    2013-10-01

    The light scattering potential of titanium dioxide (TiO2) is maximized when the TiO2 particles are correctly spaced in relation to the size of the particles, their spacing distance and the refractive index contrast with the surrounding medium. Nanoparticle extenders are claimed to improve TiO2 spacing due to the small particles acting to separate larger TiO2 particles (void size in respect to the separation of the surfaces ˜0.2 µm) and so preventing the TiO2 particles from reaching optical crowding. This concept has been challenged by previous work (Diebold 2011 J. Coat. Technol. Res. 8 541-52) using a combination of Monte Carlo simulations and image analysis techniques. Surprisingly in the light of traditional interpretations, the results showed that nanoparticles did not, in fact, space TiO2 particles under any conditions examined. Instead, TiO2 distributions and spacings were completely indifferent to the presence of smaller particles. This current paper undertakes to study why in certain cases extenders do in fact deliver significant synergy allowing TiO2 levels to be reduced in practice. The use of nano-calcium carbonate is demonstrated to provide a wide range of synergistic extension of TiO2 when in combination with synthetic latex binder, but, as found in the previous theoretical work, only a limited synergistic range in direct pigment packing studies using slurry pigment mixes only. A schematic model of the action of calcium carbonate containing a high nanoparticle fraction in the presence of binder is proposed, and is related to a combination of the potential reduction of contact between latex and TiO2 related to an increase in effective pigment volume fraction and surface area as well as the potential for differential flocculation. This model is supported by electron microscopy images and a measure of the ‘hardness’ of the skeletal elements making up the coating structure, determined via the bulk modulus using mercury intrusion porosimetry, enabling

  15. Taking a fresh look at optical crowding of TiO2: the role of nanocarbonate as synergistic optical extender

    International Nuclear Information System (INIS)

    Ridgway, Cathy J; Gane, Patrick A C

    2013-01-01

    The light scattering potential of titanium dioxide (TiO 2 ) is maximized when the TiO 2 particles are correctly spaced in relation to the size of the particles, their spacing distance and the refractive index contrast with the surrounding medium. Nanoparticle extenders are claimed to improve TiO 2 spacing due to the small particles acting to separate larger TiO 2 particles (void size in respect to the separation of the surfaces ∼0.2 µm) and so preventing the TiO 2 particles from reaching optical crowding. This concept has been challenged by previous work (Diebold 2011 J. Coat. Technol. Res. 8 541–52) using a combination of Monte Carlo simulations and image analysis techniques. Surprisingly in the light of traditional interpretations, the results showed that nanoparticles did not, in fact, space TiO 2 particles under any conditions examined. Instead, TiO 2 distributions and spacings were completely indifferent to the presence of smaller particles. This current paper undertakes to study why in certain cases extenders do in fact deliver significant synergy allowing TiO 2 levels to be reduced in practice. The use of nano-calcium carbonate is demonstrated to provide a wide range of synergistic extension of TiO 2 when in combination with synthetic latex binder, but, as found in the previous theoretical work, only a limited synergistic range in direct pigment packing studies using slurry pigment mixes only. A schematic model of the action of calcium carbonate containing a high nanoparticle fraction in the presence of binder is proposed, and is related to a combination of the potential reduction of contact between latex and TiO 2 related to an increase in effective pigment volume fraction and surface area as well as the potential for differential flocculation. This model is supported by electron microscopy images and a measure of the ‘hardness’ of the skeletal elements making up the coating structure, determined via the bulk modulus using mercury intrusion

  16. Chemical changes induced on a TiO2 surface by electron bombardment

    International Nuclear Information System (INIS)

    Vergara, L.I.; Passeggi, M.C.G.; Ferron, J.

    2007-01-01

    We study the TiO 2 (Ti 4+ ) chemical reduction induced by electron bombardment using Auger electron spectroscopy and factor analysis. We show that the electron irradiation of a TiO 2 sample is characterized by the appearance of a lower Ti oxidation state, Ti 2 O 3 (Ti 3+ ), followed by a further deposition of carbon, which is present inevitably in the environment even under ultra-high vacuum conditions. The appearance of C over the surface is found to be a complex mechanism which affects the reduction process through passivation of the electron-induced oxygen desorption and formation of titanium carbide. For very high irradiation doses, we also found that the chemical changes on the surface are stopped due to the deposition of carbon in a graphitic form

  17. 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.

  18. 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.

  19. Photo-Catalytic Properties of TiO2 Supported on MWCNTs, SBA-15 and Silica-Coated MWCNTs Nanocomposites.

    Science.gov (United States)

    Ramoraswi, Nteseng O; Ndungu, Patrick G

    2015-12-01

    Mesoporous silica, specifically SBA-15, acid-treated multi-walled carbon nanotubes and a hybrid nanocomposite of SBA-15 coated onto the sidewalls acid-treated multi-walled carbon nanotubes (CNTs) were prepared and used as supports for anatase TiO2. Sol-gel methods were adapted for the synthesis of selected supports and for coating the materials with selected wt% loading of titania. Physical and chemical properties of the supports and catalyst composite materials were investigated by powder X-ray diffraction (XRD), Raman spectroscopy, thermogravimetric analysis, scanning electron microscope (SEM), high-resolution transmission electron microscope (HRTEM), UV-vis diffuse reflectance spectroscopy and fluorescence spectroscopy. The photo-activity of the catalyst composites were evaluated on the decolorisation of methylene blue as a model pollutant. Coating CNTs with SBA-15 improved the thermal stability and textural properties of the nanotubes. All supported titania composites had high surface areas (207-301 m(2)/g), altered band gap energies and reduced TiO2 crystallite sizes. The TiO2/SBA-CNT composite showed enhanced photo-catalytic properties and activity than the TiO2/SBA-15 and TiO2/CNT composites. In addition, an interesting observation was noted with the TiO2/SBA-15 nanocomposites, which had a significantly greater photo-catalytic activity than the TiO2/CNT nanocomposites in spite of the high electron-hole recombination phenomena observed with the photoluminescence results. Discussions in terms of morphological, textural and physical-chemical aspects to account for the result are presented.

  20. Oxygen Atom Exchange between Gaseous CO2 and TiO2 Nanoclusters

    Czech Academy of Sciences Publication Activity Database

    Civiš, Svatopluk; Ferus, Martin; Zukalová, Markéta; Zukal, Arnošt; Kavan, Ladislav; Jordan, K. D.; Sorescu, D. C.

    2015-01-01

    Roč. 119, č. 7 (2015), s. 3605-3612 ISSN 1932-7447 R&D Projects: GA ČR GA13-07724S; GA ČR(CZ) GAP108/12/0814; GA MŠk(CZ) LD13060; GA MŠk LD14115 Grant - others:COST(XE) CM1104 Institutional support: RVO:61388955 Keywords : TiO2 * carbon dioxide * nanoparticles Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.509, year: 2015

  1. Cross flow microfiltration of oil-water emulsions using clay based ceramic membrane support and TiO2 composite membrane

    OpenAIRE

    Kanchapogu Suresh; G. Pugazhenthi

    2017-01-01

    The main objective of this work is to study the effect of cross flow filtration conditions on the separation of oily wastewater using ceramic support and TiO2 membrane. Firstly, the low cost clay based ceramic membrane support was prepared by uniaxial compaction method using combination of pyrophyllite, quartz, feldspar, kaolin, ball clay and calcium carbonate along with PVA as a binder. Subsequently, TiO2 composite membrane was fabricated via hydrothermal route employing TiO2 sol derived fro...

  2. A novel synthesis method for TiO2 particles with magnetic Fe3O4 cores.

    Science.gov (United States)

    Dong, Qi; Zhang, Keqiang; An, Yi

    2014-01-01

    TiO2@(AC/Fe3O4) (AC is activated carbon) was prepared by using AC and Fe3O4 as joint support. The morphological features, crystal structure, and magnetism of the final product were characterized. The results indicate that TiO2 particles formed on the surface of AC and Fe3O4; the sizes of TiO2 and Fe3O4 were 0.5 and 0.7 μm respectively, and that of AC fell within a wide range. The highly crystalline cubic structures of the TiO2 particles was in accord with the standard X-ray diffractometry spectrum of magnetite and anatase. The maximum saturation magnetization of TiO2@(AC/Fe3O4) was 75 emu g(-1), which was enough to support magnetic recovery. The rate of methylene blue (MB) removal photocatalyzed by TiO2@(AC/Fe3O4) was higher by 50% than that achieved with AC/Fe3O4 photocatalysis, and similar to that achieved with TiO2@AC. The removal rate (kobs) decreased drastically from 1.77 × 10(-2) to 9.36 × 10(-3)min(-1) when the initial concentration of MB solution increased from 2.0 to 5.0 mg L(-1). The kobs value increased from 9.41 × 10(-3) to 1.34 × 10(-2)min(-1) with increasing photocatalyst dosage from 0.2 to 1.0 g, then slightly decreased to 1.33 × 10(-2)min(-1) at 2.0 g dosage.

  3. 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.

  4. 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.

  5. Polymer dots grafted TiO2 nanohybrids as high performance visible light photocatalysts.

    Science.gov (United States)

    Li, Gen; Wang, Feng; Liu, Peng; Chen, Zheming; Lei, Ping; Xu, Zhongshan; Li, Zengxi; Ding, Yanfen; Zhang, Shimin; Yang, Mingshu

    2018-04-01

    As a new member of carbon dots (CDs), Polymer dots (PDs) prepared by hydrothermal treatment of polymers, usually consist of the carbon core and the connected partially degraded polymer chains. This type of CDs might possess aqueous solubility, non-toxicity, excellent stability against photo-bleaching and high visible light activity. In this research, PDs were prepared by a moderate hydrothermal treatment of polyvinyl alcohol, and PDs grafted TiO 2 (PDs-TiO 2 ) nanohybrids with TiOC bonds were prepared by a facile in-situ hydrothermal treatment of PDs and Ti (SO 4 ) 2 . Under visible light irradiation, the PDs-TiO 2 demonstrate excellent photocatalytic activity for methyl orange degradation, and the photocatalytic rate constant of PDs-TiO 2 is 3.6 and 9.5 times higher than that of pure TiO 2 and commercial P25, respectively. In addition, the PDs-TiO 2 exhibit good recycle stability under UV-Vis light irradiation. The interfacial TiOC bonds and the π-conjugated structures in PDs-TiO 2 can act as the pathways to quickly transfer the excited electrons between PDs and TiO 2 , therefore contribute to the excellent photocatalytic activity. Copyright © 2018 Elsevier Ltd. All rights reserved.

  6. 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.

  7. 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).

  8. Facile fabrication of robust TiO2@SnO2@C hollow nanobelts for outstanding lithium storage

    Science.gov (United States)

    Tian, Qinghua; Li, Lingxiangyu; Chen, Jizhang; Yang, Li; Hirano, Shin-ichi

    2018-02-01

    Elaborate fabrication of state-of-the-art nanostructure SnO2@C-based composites greatly contributes to alleviate the huge volume expansion issue of the SnO2 anodes. But the preparation processes of most of them are complicated and tedious, which is generally adverse to the development of SnO2@C-based composite anodes. Herein, a unique nanostructure of TiO2@SnO2@C hollow nanobelts (TiO2@SnO2@C HNBs), including the characteristics of one-dimensional architecture, sandwich protection, hollow structure, carbon coating, and a mechanically robust TiO2 support, has been fabricated by a facile approach for the first time. As anodes for lithium-ion batteries, the as-fabricated TiO2@SnO2@C HNBs exhibit an outstanding lithium storage performance, delivering capacity of 804.6 and 384. 5 mAh g-1 at 200 and even 1000 mA g-1 after 500 cycles, respectively. It is demonstrated that thus outstanding performance is mainly attributed to the unique nanostructure of TiO2@SnO2@C HNBs.

  9. 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

  10. X-ray and EPR study of reactions between B4C and TiO2

    International Nuclear Information System (INIS)

    Kakazey, M.; Vlasova, M.; Gonzalez-Rodriguez, J.G.; Dominguez-Patino, M.; Leder, R.

    2006-01-01

    X-ray diffraction and electron paramagnetic resonance (EPR) methods have been used to study the reaction process in a system of 95 wt.% of B 4 C + 5 wt.% TiO 2 . The addition of TiO 2 to B 4 C was effective in accelerating the removal of carbon inclusions. Two types of reactions between B 4 C and TiO 2 , starting at temperatures ∼1173 K, took place: (a) gas-transport exchange and (b) diffusion of Ti atoms into the B 4 C lattice. These reactions modify the number and type of donor centers in the B 4 C. The dependence of EPR line width on the number of donor centers in B 4 C (from conditions of sample treatment) is a useful method for investigating the formation of powders and ceramics based on B 4 C

  11. Single-step preparation of TiO2/MWCNT Nanohybrid materials by laser pyrolysis and application to efficient photovoltaic energy conversion.

    Science.gov (United States)

    Wang, Jin; Lin, Yaochen; Pinault, Mathieu; Filoramo, Arianna; Fabert, Marc; Ratier, Bernard; Bouclé, Johann; Herlin-Boime, Nathalie

    2015-01-14

    This paper presents the continuous-flowand single-step synthesis of a TiO2/MWCNT (multiwall carbon nanotubes) nanohybrid material. The synthesis method allows achieving high coverage and intimate interface between the TiO2particles and MWCNTs, together with a highly homogeneous distribution of nanotubes within the oxide. Such materials used as active layer in theporous photoelectrode of solid-state dye-sensitized solar cells leads to a substantial performance improvement (20%) as compared to reference devices.

  12. Enhanced H2/CH4 and H2/CO2 Separation by Carbon Molecular Sieve Membrane Coated on Titania Modified Alumina Support: Effects of TiO2 Intermediate Layer Preparation Variables on Interfacial Adhesion.

    Czech Academy of Sciences Publication Activity Database

    Tseng, H.-H.; Wang, Ch.-T.; Zhuang, G.-L.; Uchytil, Petr; Řezníčková Čermáková, Jiřina; Setničková, Kateřina

    2016-01-01

    Roč. 510, JUL 15 (2016), s. 391-404 ISSN 0376-7388 Grant - others:NSC(TW) NSC100-2221-E- 040-004-MY3 Institutional support: RVO:67985858 Keywords : carbon membrane * intermediate layer * adhesion Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 6.035, year: 2016

  13. ??????????? ??????????????? ????? ??????-???????? ????????????? ?????????? ??????? ?aO?Al2O3?TiO2 ??? ???????? ?????? ?????

    OpenAIRE

    ???????, ????; ??????, ?????????

    2011-01-01

    ? ????? ?????? ?????????? ???????? ?????????????? ??????????? ????????????? ??? ??????-????????? ???????????????? ?????????? ??????? ?aO?Al2O3?TiO2, ?? ???????? ??????? ? ???????????? ??????? ??? ???????? ? ?????? ????????? ?????? ?????. ???????? ?????????? ???????? ??? ??????????? ?????????? ??????? ????????? ???????????? ?????????? ??? ??????????? 12000?, ?? ????????? ?????????????? ????????????? ???????, ????????? ???? ? ?????????? ????? ???????? ??????? ???????????. ????????, ?? ?? ...

  14. Thermal degradation of TiO2 nanotubes on titanium

    Science.gov (United States)

    Shivaram, Anish; Bose, Susmita; Bandyopadhyay, Amit

    2014-10-01

    The objective of this research was to study thermal degradation behavior of TiO2 nanotubes on titanium (Ti). TiO2 nanotubes were grown via anodization method on commercially pure Ti (Cp-Ti) discs using two different electrolytes, 1 vol. % HF in deionized (DI) water and 1 vol. % HF + 0.5 wt. % NH4F + 10 vol. % DI water in ethylene glycol, to obtain nanotubes with two different lengths, 300 nm and 950 nm keeping the nanotube diameter constant at 100 ± 20 nm. As grown TiO2 nanotubes were subjected to heat treatment to understand thermal degradation as a function of both temperature and hold time. The signs of degradation were observed mainly when amorphous nanotubes started to crystallize, however the crystallization temperature varied based on TiO2 nanotubes length and anodizing condition. Overall, 300 nm nanotubes were thermally stable at least up to 400 °C for 12 h, while the 950 nm long nanotubes show signs of degradation from 400 °C for 6 h only. Clearly, length of nanotubes, heat treatment temperature as well as hold times show influence toward degradation kinetics of TiO2 nanotubes on titanium.

  15. Discoloration of a red cationic dye by supported TiO2 photocatalysis

    International Nuclear Information System (INIS)

    Mounir, B.; Pons, M.N.; Zahraa, O.; Yaacoubi, A.; Benhammou, A.

    2007-01-01

    The degradation under UV, visible and sunlight irradiation of C.I. Basic Red 46 (BR 46) dye used for acrylic fibers dyeing has been studied in a lab-scale continuous system with two different immobilized TiO 2 systems. Catalyst I was based on TiO 2 particles deposited on cellulose fibers; Catalyst II combined TiO 2 particles deposited on a layer of cellulose fibers (as in Catalyst I) with a layer of carbon fibers and finally a layer of cellulose fibers. The treatment of aqueous dye solutions and industrial wastewater contaminated with the same dye has been evaluated in terms of color removal and chemical oxygen demand (COD) decrease. With UV light, aqueous solutions containing dye were decolorized slightly more rapidly with Catalyst II than with Catalyst I. Sunlight was also very effective and experiments involving sunlight irradiation showed Catalyst II to be the more efficient, giving more than 90% discoloration after 20 min of treatment. Comparing the discoloration yield by adsorption or under visible light for both catalysts, it was observed that the difference between them is below 5%. The adsorption kinetics was found to follow a second-order rate law for Catalyst I and a first-order rate law for Catalyst II. The kinetics of photocatalytic degradation under UV or sunlight were found to follow a first-order rate law for both catalytic systems. Under sunlight the COD removal yield for textile wastewater reaches 33% with Catalyst I against 93% with Catalyst II

  16. Composite TiO2/clays materials for photocatalytic NOx oxidation

    Science.gov (United States)

    Todorova, N.; Giannakopoulou, T.; Karapati, S.; Petridis, D.; Vaimakis, T.; Trapalis, C.

    2014-11-01

    TiO2 photocatalyst received much attention for air purification applications especially for removal of air pollutants like NOx, VOCs etc. It has been established that the activity of the photocatalyst can be significantly enhanced by its immobilization onto suitable substrates like inorganic minerals, porous silica, hydroxyapatite, adsorbent materials like activated carbon, various co-catalysts such as semiconductors, graphene, reduced graphite oxide, etc. In the present work, photocatalytic composite materials consisted of mineral substrate and TiO2 in weight ratio 1:1 were manufactured and examined for oxidation and removal of nitric oxides NOx (NO and NO2). Commercial titania P25 (Evonik-Degussa) and urea-modified P25 were used as photocatalytically active components. Inorganic minerals, namely kunipia, talk and hydrotalcite were selected as supporting materials due to their layered structure and expected high NOx adsorption capability. Al3+ and Ca2+ intercalation was applied in order to improve the dispersion of TiO2 and its loading into the supporting matrix. The X-ray diffraction analysis and Scanning Electron Microscopy revealed the binary structure of the composites and homogeneous dispersion of the photocatalyst into the substrates. The photocatalytic behavior of the materials in NOx oxidation and removal was investigated under UV and visible light irradiation. The composite materials exhibited superior photocatalytic activity than the bare titania under both types of irradiation. Significant visible light activity was recorded for the composites containing urea-modified titania that was accredited to the N-doping of the semiconductor. Among the different substrates, the hydrotalcite caused highest increase in the NOx removal, while among the intercalation ions the Ca2+ was more efficient. The results were related to the improved dispersion of the TiO2 and the synergetic activity of the substrates as NOx adsorbers.

  17. 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

  18. 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.

  19. Microwave-assisted synthesis of C-doped TiO2 and ZnO hybrid nanostructured materials as quantum-dots sensitized solar cells

    Science.gov (United States)

    Rangel-Mendez, Jose R.; Matos, Juan; Cházaro-Ruiz, Luis F.; González-Castillo, Ana C.; Barrios-Yáñez, Guillermo

    2018-03-01

    The microwave-assisted solvothermal synthesis of C-doped TiO2 and ZnO hybrid materials was performed. Saccharose, titanium isopropoxide and zinc acetate were used as organic and inorganic sources for the synthesis. The influence of temperature and reaction time on the textural and optoelectronic properties of the hybrid materials was verified. Carbon quantum-dots of TiO2 and ZnO nanostructured spheres were obtained in a second pot by controlled calcination steps of the precursor hybrid materials. A carefully characterization by adsorption-desorption N2 isotherms, XRD, XPS, SEM, UV-vis/DR and electro- and photo-electrochemistry properties of the carbon quantum-dots TiO2 and ZnO spheres was performed. The photoelectrochemical activity of TiO2-C and ZnO-C films proved to be dependent on the conditions of synthesis. It was found a red-shift in the energy band gap of the semiconductors with values of 3.02 eV and 3.13 eV for the TiO2-C and ZnO-C, respectively, clearly lower than those on bare semiconductors, which is associated with the C-doping effect. From the photo-electrochemistry characterization of C-doped TiO2 and ZnO films can be concluded that the present materials have potential applications as photoelectrodes for quantum-dots sensitized solar cells.

  20. Uniform Gold-Nanoparticle-Decorated {001}-Faceted Anatase TiO2 Nanosheets for Enhanced Solar-Light Photocatalytic Reactions.

    Science.gov (United States)

    Shi, Huimin; Zhang, Shi; Zhu, Xupeng; Liu, Yu; Wang, Tao; Jiang, Tian; Zhang, Guanhua; Duan, Huigao

    2017-10-25

    The {001}-faceted anatase TiO 2 micro-/nanocrystals have been widely investigated for enhancing the photocatalysis and photoelectrochemical performance of TiO 2 nanostructures, but their practical applications still require improved energy conversion efficiency under solar-light and enhanced cycling stability. In this work, we demonstrate the controlled growth of ultrathin {001}-faceted anatase TiO 2 nanosheets on flexible carbon cloth for enhancing the cycling stability, and the solar-light photocatalytic performance of the synthesized TiO 2 nanosheets can be significantly improved by decorating with vapor-phase-deposited uniformly distributed plasmonic gold nanoparticles. The fabricated Au-TiO 2 hybrid system shows an 8-fold solar-light photocatalysis enhancement factor in photodegrading Rhodamine B, a high photocurrent density of 300 μA cm -2 under the illumination of AM 1.5G, and 100% recyclability under a consecutive long-term cycling measurement. Combined with electromagnetic simulations and systematic control experiments, it is believed that the tandem-type separation and transition of plasmon-induced hot electrons from Au nanoparticles to the {001} facet of anatase TiO 2 , and then to the neighboring {101} facet, is responsible for the enhanced solar-light photochemical performance of the hybrid system. The Au-TiO 2 nanosheet system addresses well the problems of the limited solar-light response of anatase TiO 2 and fast recombination of photogenerated electron-hole pairs, representing a promising high-performance recyclable solar-light-responding system for practical photocatalytic reactions.

  1. Optimization of sulfamethoxazole degradation by TiO2/hydroxyapatite composite under ultraviolet irradiation using response surface methodology

    International Nuclear Information System (INIS)

    Chun, Suk Young; Kim, Ji Tae; Chang, Soon Woong; An, Sang Woo; Lee, Si Jin

    2014-01-01

    A titanium dioxide/hydroxyapatite/ultraviolet (TiO 2 /HAP/UV-A) system was used to remove sulfamethoxazole (SMX) from water in a second-order response surface methodology (RSM) experiment with a three-level Box-Behnken design (BBD) for optimization. The effects of both the primary and secondary interaction effects of three photocatalytic reaction variables were examined: the concentration of SMX (X 1 ), dose of TiO 2 /HAP composite (X 2 ), and UV intensity (X 3 ). The UV intensity and TiO 2 /HAP dose significantly influence the SMX and total organic carbon (TOC) removal (p<0.001). However, the SMX and TOC removal are enhanced with increasing TiO 2 /HAP dose up to certain levels, and further increases in the TiO 2 /HAP dose result in adverse effects due to hydroxyl radical scavenging at higher catalyst concentrations. Complete removal of SMX was achieved upon UV-A irradiation for 180 min. Under optimal conditions, 51.2% of the TOC was removed, indicating the formation of intermediate products during SMX degradation. The optimal ratio of SMX (mg L -1 ) to TiO 2 /HAP (g L -1 ) to UV (W/L) was 5.4145 mg L -1 to 1.4351 g L -1 to 18 W for both SMX and TOC removal. By comparison with actual applications, the experimental results were found to be in good agreement with the model's predictions, with mean results for SMX and TOC removal of 99.89% and 51.01%, respectively

  2. Biomolecule-controlled hydrothermal synthesis of C-N-S-tridoped TiO2 nanocrystalline photocatalysts for NO removal under simulated solar light irradiation.

    Science.gov (United States)

    Wang, Yawen; Huang, Yu; Ho, Wingkei; Zhang, Lizhi; Zou, Zhigang; Lee, Shuncheng

    2009-09-30

    In this study, C-N-S-tridoped titanium dioxide (TiO(2)) nanocrystals were synthesized by using a facile hydrothermal method in the presence of a biomolecule l-cysteine. This biomolecule could not only serve as the common source for the carbon, sulfur and nitrogen tridoping, but also could control the final crystal phases and morphology. The resulting materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption and UV-vis diffuse reflectance spectroscopy. XPS analysis revealed that S was incorporated into the lattice of TiO(2) through substituting oxygen atoms, N might coexist in the forms of N-Ti-O and Ti-O-N in tridoped TiO(2) and most C could form a mixed layer of carbonate species deposited on the surface of TiO(2) nanoparticles. The photocatalytic activities of the samples were tested on the removal of NO at typical indoor air level in a flow system under simulated solar light irradiation. The tridoped TiO(2) samples showed much higher removal efficiency than commercial P25 and the undoped counterpart photocatalyst. The enhanced visible light photocatalytic activity of C-N-S-tridoped TiO(2) nanocrystals was explained on the basis of characterizations. The possible formation process of the monodispersed C-N-S-tridoped anatase TiO(2) nanocrystals was also proposed. This study provides a new method to prepare visible light active TiO(2) photocatalyst.

  3. Biomolecule-controlled hydrothermal synthesis of C-N-S-tridoped TiO2 nanocrystalline photocatalysts for NO removal under simulated solar light irradiation

    International Nuclear Information System (INIS)

    Wang Yawen; Huang Yu; Ho Wingkei; Zhang Lizhi; Zou Zhigang; Lee Shuncheng

    2009-01-01

    In this study, C-N-S-tridoped titanium dioxide (TiO 2 ) nanocrystals were synthesized by using a facile hydrothermal method in the presence of a biomolecule L-cysteine. This biomolecule could not only serve as the common source for the carbon, sulfur and nitrogen tridoping, but also could control the final crystal phases and morphology. The resulting materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption and UV-vis diffuse reflectance spectroscopy. XPS analysis revealed that S was incorporated into the lattice of TiO 2 through substituting oxygen atoms, N might coexist in the forms of N-Ti-O and Ti-O-N in tridoped TiO 2 and most C could form a mixed layer of carbonate species deposited on the surface of TiO 2 nanoparticles. The photocatalytic activities of the samples were tested on the removal of NO at typical indoor air level in a flow system under simulated solar light irradiation. The tridoped TiO 2 samples showed much higher removal efficiency than commercial P25 and the undoped counterpart photocatalyst. The enhanced visible light photocatalytic activity of C-N-S-tridoped TiO 2 nanocrystals was explained on the basis of characterizations. The possible formation process of the monodispersed C-N-S-tridoped anatase TiO 2 nanocrystals was also proposed. This study provides a new method to prepare visible light active TiO 2 photocatalyst.

  4. Influence of Pore Size on the Optical and Electrical Properties of Screen Printed TiO2 Thin Films

    Directory of Open Access Journals (Sweden)

    Dinfa Luka Domtau

    2016-01-01

    Full Text Available Influence of pore size on the optical and electrical properties of TiO2 thin films was studied. TiO2 thin films with different weight percentages (wt% of carbon black were deposited by screen printing method on fluorine doped tin oxide (FTO coated on glass substrate. Carbon black decomposed on annealing and artificial pores were created in the films. All the films were 3.2 µm thick as measured by a surface profiler. UV-VIS-NIR spectrophotometer was used to study transmittance and reflectance spectra of the films in the photon wavelength of 300–900 nm while absorbance was studied in the range of 350–900 nm. Band gaps and refractive index of the films were studied using the spectra. Reflectance, absorbance, and refractive index were found to increase with concentrations of carbon black. There was no significant variation in band gaps of films with change in carbon black concentrations. Transmittance reduced as the concentration of carbon black in TiO2 increased (i.e., increase in pore size. Currents and voltages (I-V characteristics of the films were measured by a 4-point probe. Resistivity (ρ and conductivity (σ of the films were computed from the I-V values. It was observed that resistivity increased with carbon black concentrations while conductivity decreased as the pore size of the films increased.

  5. Sulphur doped nanoparticles of TiO2

    Czech Academy of Sciences Publication Activity Database

    Szatmáry, Lórant; Bakardjieva, Snejana; Šubrt, Jan; Bezdička, Petr; Jirkovský, Jaromír; Bastl, Zdeněk; Brezová, V.; Korenko, M.

    2011-01-01

    Roč. 161, č. 1 (2011), s. 23-28 ISSN 0920-5861 R&D Projects: GA MŠk 1M0577 Institutional research plan: CEZ:AV0Z40400503; CEZ:AV0Z40320502 Keywords : photocatalyst * S-doped TiO2 * Thiourea Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.407, year: 2011

  6. Impedance spectroscopy studies of surface engineered TiO2 ...

    Indian Academy of Sciences (India)

    Administrator

    Impedance; nanoTiO2; self-assembled monolayers; electrical resistivity; permittivity. 1. Introduction ... search studies showed that nanostructured TiO2 ceramics possess ..... tion handbook (ed) J Cazes (New York: Marcel Dekker). 3rd ed, p ...

  7. Supercritical Flow Synthesis of TiO2

    DEFF Research Database (Denmark)

    Hellstern, Henrik Christian; Becker, Jacob; Hald, Peter

    2014-01-01

    A new, up-scaled supercritical flow synthesis apparatus has been constructed in Aarhus. A module based system allows for a range of parameter studies with improved parameter control. The dual-reactor setup enables both single phase and core-shell nanoparticle synthesis. TiO2 is a well-known mater...

  8. Fluoropolymer - TiO2 coatings and their superhydrophilicity

    DEFF Research Database (Denmark)

    Søgaard, Erik Gydesen; Simonsen, Morten Enggrob; Jepsen, Henrik

    In this work the superhydrophilicity of coatings on fluoropolymer were investigated. The different coatings were prepared by help of P25 Degussa TiO2 powder, titaniumisopropoxide, Lumiflon® and two different curing agents (BL 3175 and Cymel 303). The investigations were performed by help of a sta...

  9. High-pressure polymorphs of anatase TiO2

    DEFF Research Database (Denmark)

    Arlt, T.; Bermejo, M.; Blanco, M. A.

    2000-01-01

    The equation of state of anatase TiO2 has been determined experimentally-using polycrystalline as well as single-crystal material-and compared with theoretical calculations using the ab initio perturbed ion model. The results are highly consistent, the zero-pressure bulk modulus being 179(2) GPa ...

  10. Protein Corona Prevents TiO2 Phototoxicity.

    Directory of Open Access Journals (Sweden)

    Maja Garvas

    Full Text Available TiO2 nanoparticles have generally low toxicity in the in vitro systems although some toxicity is expected to originate in the TiO2-associated photo-generated radical production, which can however be modulated by the radical trapping ability of the serum proteins. To explore the role of serum proteins in the phototoxicity of the TiO2 nanoparticles we measure viability of the exposed cells depending on the nanoparticle and serum protein concentrations.Fluorescence and spin trapping EPR spectroscopy reveal that the ratio between the nanoparticle and protein concentrations determines the amount of the nanoparticles' surface which is not covered by the serum proteins and is proportional to the amount of photo-induced radicals. Phototoxicity thus becomes substantial only at the protein concentration being too low to completely coat the nanotubes' surface.These results imply that TiO2 nanoparticles should be applied with ligands such as proteins when phototoxic effects are not desired - for example in cosmetics industry. On the other hand, the nanoparticles should be used in serum free medium or any other ligand free medium, when phototoxic effects are desired - as for efficient photodynamic cancer therapy.

  11. TiO2--a prototypical memristive material.

    Science.gov (United States)

    Szot, K; Rogala, M; Speier, W; Klusek, Z; Besmehn, A; Waser, R

    2011-06-24

    Redox-based memristive switching has been observed in many binary transition metal oxides and related compounds. Since, on the one hand, many recent reports utilize TiO(2) for their studies of the memristive phenomenon and, on the other hand, there is a long history of the electronic structure and the crystallographic structure of TiO(2) under the impact of reduction and oxidation processes, we selected this material as a prototypical material to provide deeper insight into the mechanisms behind memristive switching. In part I, we briefly outline the results of the historical and recent studies of electroforming and resistive switching of TiO(2)-based cells. We describe the (tiny) stoichiometrical range for TiO(2 - x) as a homogeneous compound, the aggregation of point defects (oxygen vacancies) into extended defects, and the formation of the various Magnéli phases. Furthermore, we discuss the driving forces for these solid-state reactions from the thermodynamical point of view. In part II, we provide new experimental details about the hierarchical transformation of TiO(2) single crystals into Magnéli phases, and vice versa, under the influence of chemical, electrical and thermal gradients, on the basis of the macroscopic and nanoscopic measurements. Those include thermogravimetry, high-temperature x-ray diffraction (XRD), high-temperature conductivity measurements, as well as low-energy electron diffraction (LEED), x-ray photoelectron spectroscopy (XPS), and LC-AFM (atomic force microscope equipped with a conducting tip) studies. Conclusions are drawn concerning the relevant parameters that need to be controlled in order to tailor the memristive properties.

  12. TiO2/ CNT hetero-structure with variable electron beam diameter suitable for nano lithography

    International Nuclear Information System (INIS)

    Barati, F.; Abdi, Y.; Arzi, E.

    2012-01-01

    We report fabrication of a novel TiO 2 /carbon nano tube based field emission device suitable for nano lithography and fabrication of transistor. The growth of carbon nano tubes is performed on silicon substrates using plasma-enhanced chemical vapor deposition method. The vertically grown carbon nano tubes are encapsulated by TiO 2 using an atmospheric pressure chemical vapor deposition system. Field emission from the carbon nano tubes is realized by mechanical polishing of the prepared nano structure. The possibility of the application of such nano structures as a lithography tool with variable electron beam diameter was investigated. The obtained results show that spot size of less than 30 nm can be obtained by applying a proper voltage on TiO 2 surrounding gate. Electrical measurements of the fabricated device confirm the capability of this nano structure for the fabrication of field emission based field effect transistor. By applying a voltage between the gate and the cathode electrode, the emission current from carbon nano tubes shows a significant drop, indicating proper control of gate on the emission current.

  13. A review on the effects of TiO2 surface point defects on CO2 photoreduction with H2O

    Directory of Open Access Journals (Sweden)

    Huilei Zhao

    2017-03-01

    Full Text Available Photocatalytic reduction of CO2 with water by photocatalysts such as TiO2 to produce solar fuels is an attractive approach to alleviate the environmental influences of greenhouse gases and in the meantime produce valuable carbon-neutral fuels. Among the materials properties that affect catalytic activity of CO2 photoreduction, the point defect on TiO2 is one of the most important but not frequently addressed and well understood in the literature. In this review, we have examined the major influences of TiO2 point defects on CO2 photoreduction with H2O, by changing the catalysts' gas adsorption capabilities, optical properties, and electronic structures. In addition, the performances of various defective TiO2 toward CO2 photoreduction are summarized and compared in terms of productivity, selectivity, and stability. We hope this review can contribute to understanding the mechanism of CO2 photoreduction on defective TiO2 and provide insights to the design of highly efficient defect-rich TiO2 to boost the CO2 utilization.

  14. Dripping and evolution behavior of primary slag bearing TiO2 through the coke packed bed in a blast-furnace hearth

    Science.gov (United States)

    Liu, Yan-xiang; Zhang, Jian-liang; Wang, Zhi-yu; Jiao, Ke-xin; Zhang, Guo-hua; Chou, Kuo-chih

    2017-02-01

    To investigate the flow of primary slag bearing TiO2 in the cohesive zone of blast furnaces, experiments were carried out based on the laboratory-scale packed bed systems. It is concluded that the initial temperature of slag dripping increases with decreasing FeO content and increasing TiO2 content. The slag holdup decreases when the FeO content is in the range of 5wt%-10wt%, whereas it increases when the FeO content exceeds 10wt%. Meanwhile, the slag holdup decreases when the TiO2 content increases from 5wt% to 10wt% but increases when the TiO2 content exceeds 10wt%. Moreover, slag/coke interface analysis shows that the reaction between FeO and TiO2 occurs between the slag and the coke. The slag/coke interface is divided into three layers: slag layer, iron-rich layer, and coke layer. TiO2 in the slag is reduced by carbon, and the generated Ti diffuses into iron.

  15. High photocatalytic activity of hierarchical SiO2@C-doped TiO2 hollow spheres in UV and visible light towards degradation of rhodamine B.

    Science.gov (United States)

    Zhang, Ying; Chen, Juanrong; Hua, Li; Li, Songjun; Zhang, Xuanxuan; Sheng, Weichen; Cao, Shunsheng

    2017-10-15

    Ongoing research activities are targeted to explore high photocatalytic activity of TiO 2 -based photocatalysts for the degradation of environmental contaminants under UV and visible light irradiation. In this work, we devise a facile, cost-effective technique to in situ synthesize hierarchical SiO 2 @C-doped TiO 2 (SCT) hollow spheres for the first time. This strategy mainly contains the preparation of monodisperse cationic polystyrene spheres (CPS), sequential deposition of inner SiO 2 , the preparation of the sandwich-like CPS@SiO 2 @CPS particles, and formation of outer TiO 2 . After the one-step removal of CPS templates by calcination at 450°C, hierarchical SiO 2 @C-doped TiO 2 hollow spheres are in situ prepared. The morphology, hierarchical structure, and properties of SCT photocatalyst were characterized by TEM. SEM, STEM Mapping, BET, XRD, UV-vis spectroscopy, and XPS. Results strongly confirm the carbon doping in the outer TiO 2 lattice of SCT hollow spheres. When the as-synthesized SCT hollow spheres were employed as a photocatalyst for the degradation of Rhodamine B under visible-light and ultraviolet irradiation, the SCT photocatalyst exhibits a higher photocatalytic activity than commercial P25, effectively overcoming the limitations of poorer UV activity for many previous reported TiO 2 -based photocatalysts due to doping. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Cross flow microfiltration of oil-water emulsions using clay based ceramic membrane support and TiO2 composite membrane

    Directory of Open Access Journals (Sweden)

    Kanchapogu Suresh

    2017-09-01

    Full Text Available The main objective of this work is to study the effect of cross flow filtration conditions on the separation of oily wastewater using ceramic support and TiO2 membrane. Firstly, the low cost clay based ceramic membrane support was prepared by uniaxial compaction method using combination of pyrophyllite, quartz, feldspar, kaolin, ball clay and calcium carbonate along with PVA as a binder. Subsequently, TiO2 composite membrane was fabricated via hydrothermal route employing TiO2 sol derived from TiCl4 and NH4OH solution. Cross flow microfiltration investigations were carried out by utilizing oil-water emulsion concentration of 200 mg/L at three distinct applied pressures (69–207 kPa and three cross flow velocities (0.0885, 0.1327, and 0.1769 m/s. Compared to ceramic support, TiO2 composite membrane demonstrates better performance in terms of flux and removal efficiency of oil and also the rate of flux decline during filtration operation is lower due to highly hydrophilic surface of the TiO2 membrane. TiO2 membrane displays the oil removal efficiency of 99% in the entire range of applied pressures investigation, while ceramic support shows 93–96% of oil removal.

  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. Fate of pristine TiO2 nanoparticles and aged paint-containing TiO2 nanoparticles in lettuce crop after foliar exposure.

    Science.gov (United States)

    Larue, Camille; Castillo-Michel, Hiram; Sobanska, Sophie; Trcera, Nicolas; Sorieul, Stéphanie; Cécillon, Lauric; Ouerdane, Laurent; Legros, Samuel; Sarret, Géraldine

    2014-05-30

    Engineered TiO2 nanoparticles (TiO2-NPs) are present in a large variety of consumer products, and are produced in largest amount. The building industry is a major sector using TiO2-NPs, especially in paints. The fate of NPs after their release in the environment is still largely unknown, and their possible transfer in plants and subsequent impacts have not been studied in detail. The foliar transfer pathway is even less understood than the root pathway. In this study, lettuces were exposed to pristine TiO2-NPs and aged paint leachate containing TiO2-NPs and microparticles (TiO2-MPs). Internalization and in situ speciation of Ti were investigated by a combination of microscopic and spectroscopic techniques. Not only TiO2-NPs pristine and from aged paints, but also TiO2-MPs were internalized in lettuce leaves, and observed in all types of tissues. No change in speciation was noticed, but an organic coating of TiO2-NPs is likely. Phytotoxicity markers were tested for plants exposed to pristine TiO2-NPs. No acute phytotoxicity was observed; variations were only observed in glutathione and phytochelatin levels but remained low as compared to typical values. These results obtained on the foliar uptake mechanisms of nano- and microparticles are important in the perspective of risk assessment of atmospheric contaminations. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Favorable recycling photocatalyst TiO2/CFA: Effects of loading percent of TiO2 on the structural property and photocatalytic activity

    International Nuclear Information System (INIS)

    Shi Jianwen; Chen Shaohua; Ye Zhilong; Wang Shumei; Wu Peng

    2010-01-01

    A series of photocatalysts TiO 2 /CFA were prepared using coal fly ash (CFA), waste discharged from coal-fired power plant, as substrate, and then these photocatalysts were characterized by scanning electron microscope, X-ray diffraction analysis, nitrogen adsorption test and ultraviolet-visible absorption analysis. The effects of loading percent of TiO 2 on the photocatalytic activity and re-use property of TiO 2 /CFA were evaluated by the photocatalytic decoloration and mineralization of methyl orange solution. The results show that the pore volume and the specific surface area of the TiO 2 /CFA both increased with the increase in the loading percent of TiO 2 , which improved the photocatalytic activity of TiO 2 /CFA. However, when the loading percent of TiO 2 was too high (up to 54.51%), superfluous TiO 2 was easy to break away from CFA in the course of water treatment, which was disadvantaged to the recycling property of TiO 2 /CFA. In this study, the optimal loading percent of TiO 2 was 49.97%, and the efficiencies of photocatalytic decoloration and mineralization could be maintained above 99% and 90%, respectively, when the photocatalyst was used repeatedly, without any decline, even at the sixth cycle.

  20. Superhydrophilicity of TiO2 nano thin films

    International Nuclear Information System (INIS)

    Mohammadizadeh, M.R.; Ashkarran, A.A.

    2007-01-01

    Full text: Among the several oxide semiconductors, titanium dioxide has a more helpful role in our environmental purification due to its photocatalytic activity, photo-induced superhydrophilicity, and as a result of them non-toxicity, self cleaning, and antifogging effects. After the discovery of superhydrophilicity of titanium dioxide in 1997, several researches have been performed due to its nature and useful applications. The superhydrophilicity property of the surface allows water to spread completely across the surface rather than remains as droplets, thus making the surface antifog and easy-to-clean. The distinction of photo-induced catalytic and hydrophilicity properties of TiO 2 thin films has been accepted although, the origin of hydrophilicity property has not been recognized completely yet. TiO 2 thin films on soda lime glass were prepared by the sol-gel method and spin coating process. The calcination temperature was changed from 100 to 550 C. XRD patterns show increasing the content of polycrystalline anatase phase with increasing the calcination temperature. The AFM results indicate granular morphology of the films, which particle size changes from 22 to 166 nm by increasing the calcination temperature. The RBS, EDX and Raman spectroscopy of the films show the ratio of Ti:O∼0.5, and diffusion of sodium ions from substrate into the layer, by increasing the calcination temperature. The UV/Vis. spectroscopy of the films indicates a red shift by increasing the calcination temperature. The contact angle meter experiment shows that superhydrophilicity of the films depends on the formation of anatase crystal structure and diffused sodium content from substrate to the layer. The best hydrophilicity property was observed at 450 C calcination temperature, where the film is converted to a superhydrophilic surface after 10 minutes under 2mW/cm 2 UV irradiation. TiO 2 thin film on Si(111), Si(100), and quartz substrates needs less time to be converted to superhydrophilic surface rather than glass and polycrystalline Si substrates. Our results are consistent with the idea that UV-induced wetting of TiO 2 surface is caused by the removal of hydrophobic layers of hydrocarbons by TiO 2 -mediated photo-oxidation, which leads to the attractive interaction of water with clean TiO 2 surface. (authors)

  1. 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 samples with pH 7, XRD measurements showed the coexistence of TiO2 and sodium titanate phase. By decreasing the pH during acid washing the sodium content was eliminated leaving only the main phase. This behavior was observed for samples containing Cerium concentrations up to 0.2%. The obtained nanotubes presented multiple walls, having dimensions of 5 nm of diameter and about 200 nm of length. Energy dispersive X-ray spectroscopy analyzes revealed that nanotubes are mainly composed of titanium and oxygen, with small amounts of sodium when pH is 7 and sodium no was observed for the sample obtained at pH 4. It shows that synthesis conditions are very important in order to obtain single-phase structures. In addition, TiO2 nanotubes showed good photocatalytic activity with degradation around 100 minutes.(author)

  2. 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 samples with pH 7, XRD measurements showed the coexistence of TiO2 and sodium titanate phase. By decreasing the pH during acid washing the sodium content was eliminated leaving only the main phase. This behavior was observed for samples containing Cerium concentrations up to 0.2%. The obtained nanotubes presented multiple walls, having dimensions of 5 nm of diameter and about 200 nm of length. Energy dispersive X-ray spectroscopy analyzes revealed that nanotubes are mainly composed of titanium and oxygen, with small amounts of sodium when pH is 7 and sodium no was observed for the sample obtained at pH 4. It shows that synthesis conditions are very important in order to obtain single-phase structures. In addition, TiO2 nanotubes showed good photocatalytic activity with degradation around 100 minutes.(author)

  3. Photocorrosion Mechanism of TiO2-Coated Photoanodes

    Directory of Open Access Journals (Sweden)

    Arjen Didden

    2015-01-01

    Full Text Available Atomic layer deposition was used to coat CdS photoanodes with 7 nm thick TiO2 films to protect them from photocorrosion during photoelectrochemical water splitting. Photoelectrochemical measurements indicate that the TiO2 coating does not provide full protection against photocorrosion. The degradation of the film initiates from small pinholes and shows oscillatory behavior that can be explained by an Avrami-type model for photocorrosion that is halfway between 2D and 3D etching. XPS analysis of corroded films indicates that a thin layer of CdS remains present on the surface of the corroded photoanode that is more resilient towards photocorrosion.

  4. Application of TIO2 as A sorbent for radioactive waste

    International Nuclear Information System (INIS)

    Zamroni, H.; Las, T.; Kamarz, H.

    1997-01-01

    The sorption properties of the neodymium has been studied by using TiO 2 sorbent. The experiment was carried out by batch methods to investigate the kinetic sorption, effect of pH and effect of NaNO 3 concentration in the solution. Neodymium uses for a model of trivalent actinide treated by TiO 2 which was known as materials having high thermal and radiation stabilities as well as potentially used for immobilization of waste with cement or vitrification. the results show that the optimum of kinetic sorption was obtained after one day experiment to reach the equilibrium in sorption on pH 4, and the increasing of NaNO 3 concentrations will increase the sorption of neodymium in solution (author)

  5. Investigation of the photocatalytic transformation of acesulfame K in the presence of different TiO2-based materials.

    Science.gov (United States)

    López-Muňoz, M J; Daniele, A; Zorzi, M; Medana, C; Calza, P

    2018-02-01

    The photocatalytic transformation of acesulfame K - an artificial sweetener that has gained popularity over the last decades for being a calorie-free additive in food, beverages and several pharmaceutical products - was studied using three different photocatalysts, the benchmark TiO 2 -P25 and two other forms of synthetized titanium oxides named TiO 2 -SG1 and TiO 2 -SG2. The two latter materials were synthesized by a sol gel process in which the hydrolysis rate of titanium n-butoxide was controlled by the water formed in situ through an esterification reaction between ethanol and acetic acid. The investigation included monitoring the sweetener disappearance, identifying its intermediate compounds, assessing mineralization and evaluating toxicity. The analyses were carried out using high-performance liquid chromatography (HPLC) coupled with a LTQ-Orbitrap analyzer via an electrospray ionization (ESI) in the negative ion mode. This is a powerful tool for the identification, characterization and measurement of the transformation products (TPs); overall 13 species were identified. The use of several semiconductors has pointed out differences in terms of both photocatalytic efficiency and mechanism: the assessment of the evolution kinetics of each species (TPs, total organic carbon and inorganic ions) has brought to the elaboration of a general transformation pathway of acesulfame K. TiO 2 -SG2 proved to be the most efficient material in degrading the artificial sweetener and leads to the complete mineralization within 6 h of irradiation, while up to 16 h are required for TiO 2 -P25. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. TiO2 and SiC nanostructured films, organized CNT structures

    Indian Academy of Sciences (India)

    sized nanostructured TiO2 films through hydrolysis of titanium tetra-isopropoxide. (TTIP) [9 ... structured TiO2 as a photocatalyst is as follows [15]:. TiO2(ns) ... The deposited films were easily detached from the silica tube and subjected to. SEM.

  7. 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.

  8. Enhanced Bonding of Silver Nanoparticles on Oxidized TiO2(110)

    DEFF Research Database (Denmark)

    Hansen, Jonas Ørbæk; Salazar, Estephania Lira; Galliker, Patrick

    2010-01-01

    The nucleation and growth of silver nanoclusters on TiO2(110) surfaces with on-top O adatoms (oxidized TiO2), surface O vacancies and H adatoms (reduced TiO2) have been studied. From the interplay of scanning tunneling microscopy/photoelectron spectroscopy experiments and density functional theor...

  9. Photocatalytic Water Treatment on TiO2 Thin Layers.

    Czech Academy of Sciences Publication Activity Database

    Šolcová, Olga; Spáčilová, L.; Maléterová, Ywetta; Morozová, Magdalena; Ezechiáš, Martin; Křesinová, Zdena

    2016-01-01

    Roč. 57, č. 25 (2016), s. 11631-11638 ISSN 1944-3994. [International Conference on Protection and Restoration of the Environment /12./. Skiathos Island, 29.06.2014-03.07.2014] R&D Projects: GA TA ČR TA01020804 Institutional support: RVO:67985858 ; RVO:61388971 Keywords : water purification * endocrine disruptor * photocatalytic * TiO2 layers Subject RIV: CI - Industrial Chemistry, Chemical Engineering; EE - Microbiology, Virology (MBU-M) Impact factor: 1.631, year: 2016

  10. TiO(2)-graphene nanocomposite as high performace photocatalysts

    Czech Academy of Sciences Publication Activity Database

    Štengl, Václav; Popelková, Daniela; Vláčil, P.

    2011-01-01

    Roč. 115, č. 51 (2011), s. 25209-25218 ISSN 1932-7447 R&D Projects: GA MPO(CZ) FI-IM3/061; GA MPO FI-IM5/239 Institutional research plan: CEZ:AV0Z40320502 Keywords : titanium-dioxide * visible-light * doped TiO2 * degradation * graphene * oxide Subject RIV: CA - Inorganic Chemistry Impact factor: 4.805, year: 2011

  11. Defects improved photocatalytic ability of TiO2

    International Nuclear Information System (INIS)

    Li, Lei; Tian, Hong-Wei; Meng, Fan-Ling; Hu, Xiao-Ying; Zheng, Wei-Tao; Sun, Chang Q.

    2014-01-01

    Highlights: • Defect improves the photocatalytic ability by band gap narrowing and carrier life prolonging. • Atomic undercoordination shortens the local bonds, entraps, and polarizes electrons. • Polarization lowers the local workfunction and lengthens carrier life. • Entrapment and polarization narrows the band gap tuning the wavelength of absorption. - Abstract: Defect generation forms an important means modulating the photocatalytic ability of TiO 2 with mechanisms that remain yet unclear. Here we show that a spectral distillation clarifies the impact of defect on modulating the band gap, electroaffinity, and work function of the substance. Firstly, by analyzing XPS measurements, we calibrated the 2p 3/2 level of 451.47 eV for an isolated Ti atom and its shifts by 2.14 and 6.94 eV, respectively, upon Ti and TiO 2 bulk formation. Spectral difference between the defected and the un-defected TiO 2 skin revealed then that the 2p 3/2 level shifts further from 6.94 to 9.67 eV due to the defect-induced quantum entrapment. This entrapment is associated with an elevation of the upper edges of both the 2p 3/2 and the conduction band by polarization. The shortening and strengthening of bonds between undercoordinated atoms densify and entrap the core electrons, which in turn polarize the dangling bond electrons of defect atoms. The entrapment and polarization mediate thus the band gap, the electroaffinity, the work function, and the photocatalytic ability of TiO 2

  12. Versatile preparation method for mesoporous TiO2 electrodes ...

    Indian Academy of Sciences (India)

    Unknown

    cyanate into CuI layer further enhanced the efficiency up to 2⋅75% under the irradiance .... an extremely easy way to dope films with virtually any .... to see the effect of ionic liquid on CuI, 1-ethyl-3-methyl- ... This analysis showed that TiO2 electrodes were polycrys- .... thin insulating layer of Al2O3 by using dip-coating meth-.

  13. Drug loading of nanoporous TiO2 films

    International Nuclear Information System (INIS)

    Ayon, Arturo A; Cantu, Michael; Chava, Kalpana; Agrawal, C Mauli; Feldman, Marc D; Johnson, Dave; Patel, Devang; Marton, Denes; Shi, Emily

    2006-01-01

    The loading of therapeutic amounts of drug on a nanoporous TiO 2 surface is described. This novel drug-loading scheme on a biocompatible surface, when employed on medical implants, will benefit patients who require the deployment of drug-eluting implants. Anticoagulants, analgesics and antibiotics can be considered on the associated implants for drug delivery during the time of maximal pain or risk for patients undergoing orthopedic procedures. Therefore, this scheme will maximize the chances of patient recovery. (communication)

  14. Lattice defects in rutile, TiO2

    International Nuclear Information System (INIS)

    Nakagawa, M.; Itoh, H.; Nakanishi, S.; Kondo, K.; Okada, M.; Atobe, K.

    1991-01-01

    Rutile, TiO 2 , having a relatively high melting point exhibits strong optical absorption after neutron irradiation (8 x 10 16 n f /cm 2 ) at 15K. The band peak is located near 0.96 μ, having a FWHM of 0.87 eV (at liquid nitrogen temperature). After inverse recovery at 120K, lattice defects due probably to F centers are annealed out at about 220K. (author)

  15. 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)

  16. Incorporation of chromium into TiO2 nanopowders

    International Nuclear Information System (INIS)

    Kollbek, Kamila; Sikora, Marcin; Kapusta, Czesław; Szlachetko, Jakub; Radecka, Marta; Lyson-Sypien, Barbara; Zakrzewska, Katarzyna

    2015-01-01

    Highlights: • Nanopowders of TiO 2 :Cr with different amount of Cr dopant were obtained by flame spray synthesis, FSS. • Increase in the optical absorption and a shift of the absorption edge were observed upon Cr doping. • HERFD-XANES measurements indicated that the average valence state of titanium ions was preserved. • Increasing magnetic susceptibility of a paramagnetic character was observed upon Cr doping. - Abstract: The paper reports on the results of a study of optical, electronic and magnetic properties of TiO 2 nanopowders doped with Cr ions. Diffused reflectance spectra reveal an increase in the optical absorption and a shift of the absorption edge towards lower energies upon Cr doping. Direct information on the Ti electronic state and the symmetry of its nearest environment is obtained from XANES Ti K-edge spectra. Magnetic behaviour is probed by means of the temperature dependence of DC magnetic susceptibility. Increasing magnetic susceptibility of a paramagnetic character is observed upon increasing chromium doping. The Curie constant of TiO 2 :10 at.% Cr sample (0.12 emu K/mol Oe) is lower than that expected for Cr 3+ (0.1875 emu K/mol Oe) possibly due to the appearance of Cr 4+ or the presence of the orbital contribution to the magnetic moment

  17. Thermal catalytic oxidation of octachloronaphthalene over anatase TiO2 nanomaterial and its hypothesized mechanism

    Science.gov (United States)

    Su, Guijin; Li, Qianqian; Lu, Huijie; Zhang, Lixia; Huang, Linyan; Yan, Li; Zheng, Minghui

    2015-12-01

    As an environmentally-green technology, thermal catalytic oxidation of octachloronaphthalene (CN-75) over anatase TiO2 nanomaterials was investigated at 300 °C. A wide range of oxidation intermediates, which were investigated using various techniques, could be of three types: naphthalene-ring, single-benzene-ring, and completely ring-opened products. Reactive oxygen species on anatase TiO2 surface, such as O2-• and O2-, contributed to oxidative degradation. Based on these findings, a novel oxidation degradation mechanism was proposed. The reaction at (101) surface of anatase TiO2 was used as a model. The naphthalene-ring oxidative products with chloronaphthols and hydroxyl-pentachloronaphthalene-dione, could be formed via attacking the carbon of naphthalene ring at one or more positions by nucleophilic O2-. Lateral cleavage of the naphthalene ring at different C1-C10 and C4-C9, C1-C2 and C4-C9, C1-C2 or and C3-C4 bond positions by electrophilic O2-• could occur. This will lead to the formation of tetrachlorophenol, tetrachloro-benzoic acid, tetrachloro-phthalaldehyde, and tetrachloro-acrolein-benzoic acid, partially with further transformation into tetrachlorobenzene-dihydrodiol and tetrachloro-salicylic acid. Unexpectedly, the symmetric half section of CN-75 could be completely remained with generating the intricate oxidative intermediates characteristically containing tetrachlorobenzene structure. Complete cleavage of naphthalene ring could produce the ring-opened products, such as formic and acetic acids.

  18. Effect of the nanosized TiO2 particles in Pd/C catalysts as cathode materials in direct methanol fuel cells.

    Science.gov (United States)

    Choi, Mahnsoo; Han, Choonsoo; Kim, In-Tae; Lee, Ji-Jung; Lee, Hong-Ki; Shim, Joongpyo

    2011-07-01

    Pd-TiO2/C catalysts were prepared by impregnating titanium dioxide (TiO2) on carbon-supported Pd (Pd/C) for use as the catalyst for the oxygen reduction reaction (ORR) in direct methanol fuel cells (DMFCs). Transmission electron microscope (TEM), scanning electron microscope (SEM) and X-ray diffraction (XRD) analyses were carried to confirm the distribution, morphology and structure of Pd and TiO2 on the carbon support. In fuel cell test, we confirmed that the addition of TiO2 nanoparticles make the improved catalytic activity of oxygen reduction. The electrochemical characterization of the Pd-TiO2/C catalyst for the ORR was carried out by cyclic voltammetry (CV) in the voltage window of 0.04 V to 1.2 V with scan rate of 25 mV/s. With the increase in the crystallite size of TiO2, the peak potential for OH(ads) desorption on the surface of Pd particle shifted to higher potential. This implies that TiO2 might affect the adsorption and desorption of oxygen molecules on Pd catalyst. The performance of Pd-TiO2/C as a cathode material was found to be similar to or better performance than that of Pt/C.

  19. Nb-doped TiO2 cathode catalysts for oxygen reduction reaction of polymer electrolyte fuel cells

    KAUST Repository

    Arashi, Takuya

    2014-09-01

    Nb-doped TiO2 particles were studied as electrocatalysts for the oxygen reduction reaction (ORR) under acidic conditions. The Nb-doped TiN nanoparticles were first synthesized by meso-porous C3N4 and then fully oxidized to Nb-doped TiO2 by immersing in 0.1 M H 2SO4 at 353 K for 24 h. Although the ORR activity of the as-obtained sample was low, a H2 treatment at relatively high temperature (1173 K) dramatically improved the ORR performance. An onset potential as high as 0.82 VRHE was measured. No degradation of the catalysts was observed during the oxidation-reduction cycles under the ORR condition for over 127 h. H2 treatment at temperatures above 1173 K caused the formation of a Ti4O7 phase, resulting in a decrease in ORR current. Elemental analysis indicated that the Nb-doped TiO 2 contained 25 wt% residual carbon. Calcination in air at 673 or 973 K eliminated the residual carbon in the catalyst, which was accompanied by a dramatic decrease in ORR activity. This post-calcination process may reduce the conductivity of the sample by filling the oxygen vacancies, and the carbon residue in the particle aggregates may enhance the electrocatalytic activity for ORR. The feasibility of using conductive oxide materials as electrocatalysts is discussed. © 2013 Elsevier B.V.

  20. Nb-doped TiO2 cathode catalysts for oxygen reduction reaction of polymer electrolyte fuel cells

    KAUST Repository

    Arashi, Takuya; Seo, Jeongsuk; Takanabe, Kazuhiro; Kubota, Jun; Domen, Kazunari

    2014-01-01

    Nb-doped TiO2 particles were studied as electrocatalysts for the oxygen reduction reaction (ORR) under acidic conditions. The Nb-doped TiN nanoparticles were first synthesized by meso-porous C3N4 and then fully oxidized to Nb-doped TiO2 by immersing in 0.1 M H 2SO4 at 353 K for 24 h. Although the ORR activity of the as-obtained sample was low, a H2 treatment at relatively high temperature (1173 K) dramatically improved the ORR performance. An onset potential as high as 0.82 VRHE was measured. No degradation of the catalysts was observed during the oxidation-reduction cycles under the ORR condition for over 127 h. H2 treatment at temperatures above 1173 K caused the formation of a Ti4O7 phase, resulting in a decrease in ORR current. Elemental analysis indicated that the Nb-doped TiO 2 contained 25 wt% residual carbon. Calcination in air at 673 or 973 K eliminated the residual carbon in the catalyst, which was accompanied by a dramatic decrease in ORR activity. This post-calcination process may reduce the conductivity of the sample by filling the oxygen vacancies, and the carbon residue in the particle aggregates may enhance the electrocatalytic activity for ORR. The feasibility of using conductive oxide materials as electrocatalysts is discussed. © 2013 Elsevier B.V.

  1. 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

  2. OXIDACIÓN DE p -NITROFENOL USANDO TiO 2 -ADENOSINA MONOFOSFATO I OXIDATION OF p -NITROPHENOL USING TiO 2 -ADENOSIN MONOPHOSPHATE

    Directory of Open Access Journals (Sweden)

    Carlos F. Rivas

    2018-04-01

    Full Text Available The surface of TiO2 was modified with the nucleotides adenosine 3’-monophosphate (AMP’3 and Adenosine 5’-monophosphate (AMP’5. The adsorption of nucleotides was adjusted to Langmuir ́s adsorption model, determining that the optimal condition for TiO 2 modification was at neutral pH. UV-Visible Diffuse Reflectance and IR Attenuated Total Reflectance spectra show that the chemisorption of nucleotides take placed on TiO 2 anatase. The new catalysts (TiO 2 -nucleotide improved the photodegradation of p -nitrophenol in a wide range of pH as compared with the titanium dioxide precursor. Most photoactivity was generated by using the new photocatalytic in the degradation of p -nitrophenol at pH = 6, obtaining high values for the pseudo first order kinetic constant (0.0254 min -1 and 0.0244 min -1 for TiO 2 -AMP’3 and TiO 2 -AMP’5, respectively. For all pH, the trend obtained for the photodegradation was: TiO 2 -AMP ́3 @ TiO 2 -AMP’5 > TiO 2 . Langmuir-Hinshelwood kinetics shows that the contribution of the surface reac tion rate governs the oxidation of the contaminant.

  3. Photocatalytic effects for the TiO2-coated phosphor materials

    International Nuclear Information System (INIS)

    Yoon, Jin-Ho; Jung, Sang-Chul; Kim, Jung-Sik

    2011-01-01

    Research highlights: → The photocatalytic behavior of the coupling of TiO 2 with phosphorescent materials. → The photobleaching of an MB aqueous solution under visible light irradiation. → The ALD TiO 2 -coated phosphor composite showed much higher photocatalytic reactivity. → The light emitted from the phosphors contributed to the photo-generation. - Abstract: This study investigated the photocatalytic behavior of the coupling of TiO 2 with phosphorescent materials. A TiO 2 thin film was deposited on CaAl 2 O 4 :Eu 2+ ,Nd 3+ phosphor particles by using atomic layer deposition (ALD), and its photocatalytic reaction was investigated by the photobleaching of an aqueous solution of methylene-blue (MB) under visible light irradiation. To clarify the mechanism of the TiO 2 -phosphorescent materials, two different samples of TiO 2 -coated phosphor and TiO 2 -Al 2 O 3 -coated phosphor particles were prepared. The photocatalytic mechanisms of the ALD TiO 2 -coated phosphor powders were different from those of the pure TiO 2 and TiO 2 -Al 2 O 3 -coated phosphor. The absorbance in a solution of the ALD TiO 2 -coated phosphor decreased much faster than that of pure TiO 2 under visible irradiation. In addition, the ALD TiO 2 -coated phosphor showed moderately higher photocatalytic degradation of MB solution than the TiO 2 -Al 2 O 3 -coated phosphor did. The TiO 2 -coated phosphorescent materials were characterized by transmission electron microscopy (TEM), Auger electron spectroscopy (AES) and X-ray photon spectroscopy (XPS).

  4. Synthesis of nanostructured TiO2 (anatase) and TiO2(B) in ionic liquids

    Czech Academy of Sciences Publication Activity Database

    Mansfeldová, Věra; Lásková, Barbora; Krýsová, Hana; Zukalová, Markéta; Kavan, Ladislav

    2014-01-01

    Roč. 230, JUL 2014 (2014), s. 85-90 ISSN 0920-5861 R&D Projects: GA ČR GA13-07724S; GA MŠk 7E09117 Grant - others:European Commission(XE) NMP-229036 Institutional support: RVO:61388955 Keywords : TiO2(B) * ionic liquid * electrochemistry Subject RIV: CG - Electrochemistry Impact factor: 3.893, year: 2014

  5. High pressure structural phase transitions of TiO2 nanomaterials

    International Nuclear Information System (INIS)

    Li Quan-Jun; Liu Bing-Bing

    2016-01-01

    Recently, the high pressure study on the TiO 2 nanomaterials has attracted considerable attention due to the typical crystal structure and the fascinating properties of TiO 2 with nanoscale sizes. In this paper, we briefly review the recent progress in the high pressure phase transitions of TiO 2 nanomaterials. We discuss the size effects and morphology effects on the high pressure phase transitions of TiO 2 nanomaterials with different particle sizes, morphologies, and microstructures. Several typical pressure-induced structural phase transitions in TiO 2 nanomaterials are presented, including size-dependent phase transition selectivity in nanoparticles, morphology-tuned phase transition in nanowires, nanosheets, and nanoporous materials, and pressure-induced amorphization (PIA) and polyamorphism in ultrafine nanoparticles and TiO 2 -B nanoribbons. Various TiO 2 nanostructural materials with high pressure structures are prepared successfully by high pressure treatment of the corresponding crystal nanomaterials, such as amorphous TiO 2 nanoribbons, α -PbO 2 -type TiO 2 nanowires, nanosheets, and nanoporous materials. These studies suggest that the high pressure phase transitions of TiO 2 nanomaterials depend on the nanosize, morphology, interface energy, and microstructure. The diversity of high pressure behaviors of TiO 2 nanomaterials provides a new insight into the properties of nanomaterials, and paves a way for preparing new nanomaterials with novel high pressure structures and properties for various applications. (topical review)

  6. Low temperature fabrication of perovskite solar cells with TiO2 nanoparticle layers

    International Nuclear Information System (INIS)

    Kanayama, Masato; Oku, Takeo; Suzuki, Atsushi; Yamada, Masahiro; Sakamoto, Hiroki; Minami, Satoshi; Kohno, Kazufumi

    2016-01-01

    TiO 2 /CH 3 NH 3 PbI 3 -based photovoltaic devices were fabricated by a spin-coating method using a mixture solution. TiO 2 require high-temperature processing to achieve suitably high carrier mobility. TiO 2 electron transport layers and TiO 2 scaffold layers for the perovskite were fabricated from TiO 2 nanoparticles with different grain sizes. The photovoltaic properties and microstructures of solar cells were characterized. Nanoparticle sizes of these TiO 2 were 23 nm and 3 nm and the performance of solar cells was improved by combination of two TiO 2 nanoparticles

  7. 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.

  8. First-principles atomistic Wulff constructions for an equilibrium rutile TiO2 shape modeling

    Science.gov (United States)

    Jiang, Fengzhou; Yang, Lei; Zhou, Dali; He, Gang; Zhou, Jiabei; Wang, Fanhou; Chen, Zhi-Gang

    2018-04-01

    Identifying the exposed surfaces of rutile TiO2 crystal is crucial for its industry application and surface engineering. In this study, the shape of the rutile TiO2 was constructed by applying equilibrium thermodynamics of TiO2 crystals via first-principles density functional theory (DFT) and Wulff principles. From the DFT calculations, the surface energies of six low-index stoichiometric facets of TiO2 are determined after the calibrations of crystal structure. And then, combined surface energy calculations and Wulff principles, a geometric model of equilibrium rutile TiO2 is built up, which is coherent with the typical morphology of fully-developed equilibrium TiO2 crystal. This study provides fundamental theoretical guidance for the surface analysis and surface modification of the rutile TiO2-based materials from experimental research to industry manufacturing.

  9. Composition of Surface Adsorbed Layer of TiO2 Stored in Ambient Air

    Directory of Open Access Journals (Sweden)

    Zakharenko V.S.

    2017-11-01

    Full Text Available The processes of dark, UV, and visible light promoted desorption of surface species were investigated for three different TiO2 samples: TiO2 prepared by dispersion of the titania single crystal, TiO2 prepared by combustion of a pyrotechnic mixture in air, and commercial TiO2 P25. The composition of the adsorbed layer was identified in the dark and under UV and visible light irradiation. The composition of desorption products showed the dependence of the adsorption layer state on the TiO2 nature. Methane photodesorption was detected only for the commercial TiO2 P25. Possible reasons for methane emission include the capturing of complete molecules during the TiO2 production process and photocatalytic hydrogenation of CO2 under UV-light.

  10. Study of TiO2 nanotubes as an implant application

    International Nuclear Information System (INIS)

    Hazan, Roshasnorlyza; Sreekantan, Srimala; Mydin, Rabiatul Basria S. M. N.; Mat, Ishak; Abdullah, Yusof

    2016-01-01

    Vertically aligned TiO 2 nanotubes have become the primary candidates for implant materials that can provide direct control of cell behaviors. In this work, 65 nm inner diameters of TiO 2 nanotubes were successfully prepared by anodization method. The interaction of bone marrow stromal cells (BMSC) in term of cell adhesion and cell morphology on bare titanium and TiO 2 nanotubes is reported. Field emission scanning electron microscopy (FESEM) analysis proved interaction of BMSC on TiO 2 nanotubes structure was better than flat titanium (Ti) surface. Also, significant cell adhesion on TiO 2 nanotubes surface during in vitro study revealed that BMSC prone to attach on TiO 2 nanotubes. From the result, it can be conclude that TiO 2 nanotubes are biocompatible to biological environment and become a new generation for advanced implant materials

  11. Immobilized TiO2 for Phenol Degradation in a Pilot-Scale Photocatalytic Reactor

    Directory of Open Access Journals (Sweden)

    Sylwia Mozia

    2012-01-01

    Full Text Available Phenol degradation was carried out in a photocatalytic pilot plant reactor equipped with a UV/vis mercury lamp. The total volume of treated water was equal to 1.35 m3. TiO2 P25 was used as a photocatalyst and it was immobilized on two different supports: (i a steel mesh and (ii a fiberglass cloth. Moreover, the performance of commercially available Photospheres-40 was examined. In addition, an experiment in the absence of a photocatalyst was conducted. The commercially available Photospheres-40 were found to be inadequate for the presented application due to their fragility, which in connection with vigorous mixing and pumping led to their mechanical destruction and loss of floating abilities. The highest effectiveness of phenol decomposition and mineralization was observed in the presence of TiO2 supported on the fiberglass cloth. After 15 h of the process, phenol and total organic carbon concentrations decreased by ca. 80% and 50%, respectively.

  12. Degradation of paracetamol in aqueous solutions by TiO2 photocatalysis.

    Science.gov (United States)

    Yang, Liming; Yu, Liya E; Ray, Madhumita B

    2008-07-01

    In this study, photo/photocatalytic oxidation of common analgesic and antipyretic drug, paracetamol (acetaminophen), was investigated to determine the optimal operating conditions for degradation in water. UVA (365 nm) radiation alone degraded negligible amount of paracetamol, whereas paracetamol concentration decreased substantially under an irradiation of UVC (254 nm) with marginal changes in total organic carbon (TOC). In the presence of TiO2, much faster photodegradation of paracetamol and effective mineralization occurred; more than 95% of 2.0mM paracetamol was degraded within 80 min. The degradation rate constant decreased with an increase in the initial concentration of paracetamol, while it increased with light intensity and oxygen concentration. The degradation rate also increased with TiO2 loading until a concentration of 0.8 g L(-1). The degradation rate slowly increased between pH 3.5 and 9.5, but significantly decreased with increasing pH between 9.5 and 11.0. Based on the experimental data, a kinetic equation describing paracetamol photocatalytic degradation with various process parameters is obtained.

  13. Optical Properties and Surface Morphology of Nano-composite PMMA: TiO2 Thin Films

    International Nuclear Information System (INIS)

    Lyly Nyl Ismail; Ahmad Fairoz Aziz; Habibah Zulkefle

    2011-01-01

    There are two nano-composite PMMA: TiO 2 solutions were prepared in this research. First solution is nano-composite PMMA commercially available TiO 2 nanopowder and the second solution is nano-composite PMMA with self-prepared TiO 2 powder. The self-prepared TiO 2 powder is obtained by preparing the TiO 2 sol-gel. Solvo thermal method were used to dry the TiO 2 sol-gel and obtained TiO 2 crystal. Ball millers were used to grind the TiO 2 crystal in order to obtained nano sized powder. Triton-X was used as surfactant to stabilizer the composite between PMMA: TiO 2 . Besides comparing the nano-composite solution, we also studied the effect of the thin films thickness on the optical properties and surface morphology of the thin films. The thin films were deposited by sol-gel spin coating method on glass substrates. The optical properties and surface characterization were measured with UV-VIS spectrometer equipment and atomic force microscopy (AFM). The result showed that nano-composite PMMA with self prepared TiO 2 give high optical transparency than nano-composite PMMA with commercially available TiO 2 nano powder. The results also indicate as the thickness is increased the optical transparency are decreased. Both AFM images showed that the agglomerations of TiO 2 particles are occurred on the thin films and the surface roughness is increased when the thickness is increased. High agglomeration particles exist in the AFM images for nano-composite PMMA: TiO 2 with TiO 2 nano powder compare to the other nano-composite solution. (author)

  14. Distinct toxic interactions of TiO2 nanoparticles with four coexisting organochlorine contaminants on algae.

    Science.gov (United States)

    Zhang, Shuai; Deng, Rui; Lin, Daohui; Wu, Fengchang

    Engineered nanoparticles are increasingly discharged into the environment. After discharge, these nanoparticles can interact with co-existing organic contaminants, resulting in a phenomena referred to as 'joint toxicity'. This study evaluated joint toxicities of TiO 2 nanoparticles (TiO 2 NPs) with four different (atrazine, hexachlorobenzene, pentachlorobenzene, and 3,3',4,4'-tetrachlorobiphenyl) organochlorine contaminants (OCs) toward algae (Chlorella pyrenoidosa). The potential mechanisms underlying the joint toxicity were discussed, including TiO 2 NPs-OC interactions, effects of TiO 2 NPs and OCs on biophysicochemical properties of algae and effects of TiO 2 NPs and OCs on each other's bioaccumulation in algae. The results indicate that coexposure led to a synergistic effect on the joint toxicity for TiO 2 NPs-atrazine, antagonistic effect for TiO 2 NPs-hexachlorobenzene and TiO 2 NPs-3,3',4,4'-tetrachlorobiphenyl, and an additive effect for TiO 2 NPs-pentachlorobenzene. There was nearly no adsorption of OCs by TiO 2 NPs, and the physicochemical properties of TiO 2 NPs were largely unaltered by the presence of OCs. However, both OCs and NPs affected the biophysicochemical properties of algal cells and thereby influenced the cell surface binding and/or internalization. TiO 2 NPs significantly increased the bioaccumulation of each OC. However, with the exception of atrazine, the bioaccumulation of TiO 2 NPs decreased when used with each OC. The distinct joint toxicity outcomes were a result of the balance between the increased toxicities of OCs (increased bioaccumulations) and the altered toxicity of TiO 2 NPs (bioaccumulation can either increase or decrease). These results can significantly improve our understanding of the potential environmental risks associated with NPs.

  15. Crystallization behaviour of nanostructured hybrid SiO2-TiO2 gel glasses to nanocomposites.

    Science.gov (United States)

    Tsvetelina, Gerganova; Yordanka, Ivanova; Yuliya, Vueva; Miranda, Salvado Isabel M; Helena, Fernandes Maria

    2010-04-01

    The crystallization behaviour of hybrid SiO2-TiO2 nanocomposites derived from titanosiloxanes by sol-gel method has been investigated depending on the type of siloxane precursor and the pirolysis temperature. The resulting hybrid titanosiloxanes, crosslinked with trimethylsilil isocyanate (nitrogen-modified) or methyltrietoxisilane (carbon-modified), were pirolyzed in an inert atmosphere in the temperature range between 600 to 1100 degrees C in order to form C-(N)-Si-O-TiO2 nanocomposites. By means of XRD, FTIR, 29Si NMR, SEM, TEM and AFM investigations have been established that the transformation of the nanostructured SiO2-TiO2 hybrid materials into nanocomposites as well as the crystalline size depend on the titanium content and the type of cross-linking agents used in the synthesizes.

  16. Hybrid matrices of TiO2 and TiO2–Ag nanofibers with silicone for high water flux photocatalytic degradation of dairy effluent

    DEFF Research Database (Denmark)

    Kanjwal, Muzafar Ahmad; Alm, Martin; Thomsen, Peter

    2016-01-01

    TiO2 and TiO2–Ag nanofibers were produced by electrospinning technique and surface coated on silicone elastomer (diameter: 10.0 mm; thickness: 2.0 mm) by dipcoating method. These coated hybrid nanoporous matrices were characterized by various morphological and physicochemical techniques (like SEM...

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

    KAUST Repository

    Shi, Le

    2015-01-01

    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

  18. Charge transfer between biogenic jarosite derived Fe3+and TiO2 enhances visible light photocatalytic activity of TiO2.

    Science.gov (United States)

    Chowdhury, Mahabubur; Shoko, Sipiwe; Cummings, Fransciuos; Fester, Veruscha; Ojumu, Tunde Victor

    2017-04-01

    In this work, we have shown that mining waste derived Fe 3+ can be used to enhance the photocatalytic activity of TiO 2 . This will allow us to harness a waste product from the mines, and utilize it to enhance TiO 2 photocatalytic waste water treatment efficiency. An organic linker mediated route was utilized to create a composite of TiO 2 and biogenic jarosite. Evidence of FeOTi bonding in the TiO 2 /jarosite composite was apparent from the FTIR, EFTEM, EELS and ELNEFS analysis. The as prepared material showed enhanced photocatalytic activity compared to pristine TiO 2 , biogenic jarosite and mechanically mixed sample of jarosite and TiO 2 under both simulated and natural solar irradiation. The prepared material can reduce the electrical energy consumption by 4 times compared to pristine P25 for degradation of organic pollutant in water. The material also showed good recyclability. Results obtained from sedimentation experiments showed that the larger sized jarosite material provided the surface to TiO 2 nanoparticles, which increases the settling rate of the materials. This allowed simple and efficient recovery of the catalyst from the reaction system after completion of photocatalysis. Enhanced photocatalytic activity of the composite material was due to effective charge transfer between TiO 2 and jarosite derived Fe 3+ as was shown from the EELS and ELNEFS. Generation of OH was supported by photoluminesence (PL) experiments. Copyright © 2016. Published by Elsevier B.V.

  19. Ultraviolet and Visible Photochemistry of Methanol at 3D Mesoporous Networks: TiO2 and Au-TiO2

    Science.gov (United States)

    2013-05-23

    adsorbates are known to bend the bands of n-type semi- conductors ( ZnO , TiO2, etc.) upward, 21,133,134 which drives hole diffusion toward the surface... Electrochemistry of Ω-Functionalized Alkanethiolate-Stabilized Gold Cluster Compounds. J. Am. Chem. Soc. 1996, 118 (17), 4212−4213. (48) Dagan, G.; Tomkiewicz...Tsubota, S.; Haruta, M. FTIR Study of Carbon Monoxide Oxidation and Scrambling at Room Temperature over Gold Supported on ZnO and TiO2. J. Phys. Chem

  20. Interface engineered construction of porous g-C3N4/TiO2 heterostructure for enhanced photocatalysis of organic pollutants

    Science.gov (United States)

    Li, Ya-Nan; Chen, Zhao-Yang; Wang, Min-Qiang; Zhang, Long-zhen; Bao, Shu-Juan

    2018-05-01

    A porous g-C3N4/TiO2 with hierarchical heterostructure has been successfully fabricated through a in situ assembling of small needle-like TiO2 on the surface of ultrathin g-C3N4 sheets. The ultrathin g-C3N4 sheets with carbon vacancies and rich hydroxyl groups were found to facilitate the nucleation and in situ growth of TiO2 and also to modulate the surface chemical activity of the g-C3N4/TiO2 hierarchical heterostructure. The as-designed photocatalytic heterojunction degraded Acid Orange with 82% efficiency after 10 min under simulated solar light, and possessed excellent cycle stability. Relative physical characterizations and photochemical experiments reveal that engineering the interface/surface of g-C3N4 plays a vital role in effectively constructing heterostructures of g-C3N4/TiO2, thus realizing efficient photoinduced electron-hole separation during photocatalytic process.

  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. High Photocatalytic Activity of Fe3O4-SiO2-TiO2 Functional Particles with Core-Shell Structure

    Directory of Open Access Journals (Sweden)

    Chenyang Xue

    2013-01-01

    Full Text Available This paper describes a novel method of synthesizing Fe3O4-SiO2-TiO2 functional nanoparticles with the core-shell structure. The Fe3O4 cores which were mainly superparamagnetic were synthesized through a novel carbon reduction method. The Fe3O4 cores were then modified with SiO2 and finally encapsulated with TiO2 by the sol-gel method. The results of characterizations showed that the encapsulated 700 nm Fe3O4-SiO2-TiO2 particles have a relatively uniform size distribution, an anatase TiO2 shell, and suitable magnetic properties for allowing collection in a magnetic field. These magnetic properties, large area, relative high saturation intensity, and low retentive magnetism make the particles have high dispersibility in suspension and yet enable them to be recovered well using magnetic fields. The functionality of these particles was tested by measuring the photocatalytic activity of the decolouring of methyl orange (MO and methylene blue (MB under ultraviolet light and sunlight. The results showed that the introduction of the Fe3O4-SiO2-TiO2 functional nanoparticles significantly increased the decoloration rate so that an MO solution at a concentration of 10 mg/L could be decoloured completely within 180 minutes. The particles were recovered after utilization, washing, and drying and the primary recovery ratio was 87.5%.

  3. Photocatalytic mechanism of high-activity anatase TiO2 with exposed (001) facets from molecular-atomic scale: HRTEM and Raman studies

    Science.gov (United States)

    Wu, Jun; Shi, Chentian; Zhang, Yupeng; Fu, Qiang; Pan, Chunxu

    2017-12-01

    Anatase TiO2 with a variant percentage of exposed (001) facets was prepared under hydrothermal processes by adjusting the volume of HF, and the photocatalytic mechanism was studied from atomic-molecular scale by HRTEM and Raman spectroscopy. It was revealed that: 1) From HRTEM observations, the surface of original TiO2 with exposed (001) facets was clean without impurity, and the crystal lattice was clear and completed; however, when mixed with methylene blue (MB) solution, there were many 1 nm molecular absorbed at the surface of TiO2; after the photocatalytic experiment, MB molecules disappeared and the TiO2 lattice image became fuzzy. 2) The broken path of the MB chemical bond was obtained by Raman spectroscopy, i.e., after the irradiation of the light, the vibrational mode of C-N-C disappeared due to the chemical bond breakage, and the groups containing C-N bond and carbon rings were gradually decomposed. Accordingly, we propose that the driving force for breaking the chemical bond and the disappearance of groups is from the surface lattice distortion of TiO2 during photocatalyzation.

  4. Structural properties of TiO2 nanomaterials

    Science.gov (United States)

    Kusior, Anna; Banas, Joanna; Trenczek-Zajac, Anita; Zubrzycka, Paulina; Micek-Ilnicka, Anna; Radecka, Marta

    2018-04-01

    The surface of solids is characterized by active, energy-rich sites that determine physicochemical interaction with gaseous and liquid media and possible applications in photocatalysis. The behavior of materials in such processes is related to their form and amount of various species, especially water and forms of oxygen adsorbed on the surface. The preparation of materials with controlled morphology, which includes modifications of the size, geometry, and composition, is currently an important way of optimizing properties, as many of them depend on not only the size and phase composition, but also on shape. Hydroxylated centers on the surface, which can be treated as trapping sites, are particularly significant. Water adsorbed on the surface bridging hydroxyl groups can distinctly modulate the properties of the surface of titania. The saturation of the surface with hydroxyl groups may improve the photocatalytic properties. TiO2 nanomaterials were obtained via different methods. SEM and TEM analysis were performed to study the morphology. The analysis of XRD and Raman data revealed a phase composition of obtained materials. To examine the surface properties, FTIR absorption spectra of TiO2 nanomaterials were recorded. The photocatalytic activity of titanium dioxide nanoparticles was investigated through the decomposition of methylene blue. It was demonstrated that each surface modification affects the amount of adsorbed hydroxyl groups. The different contributions of the two species to the ν(H2O) FTIR bands for different nanostructures result from the preparation conditions. It was noted that pre-adsorbed water (the surface-bridging hydroxyl) might significantly modulate the surface properties of the material. The increase in hydroxyl group density on the titanium dioxide surface enhances the effectiveness of the photocatalytic processes. It was demonstrated that flower-like titania obtained via hydrothermal synthesis exhibits the weakest catalytic activity, in contrast to the typical spherical TiO2.

  5. 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

  6. On Multiple Zagreb Indices of TiO2 Nanotubes.

    Science.gov (United States)

    Malik, Mehar Ali; Imran, Muhammad

    2015-01-01

    The First and Second Zagreb indices were first introduced by I. Gutman and N. Trinajstic in 1972. It is reported that these indices are useful in the study of anti-inflammatory activities of certain chemical instances, and in elsewhere. Recently, the first and second multiple Zagreb indices of a graph were introduced by Ghorbani and Azimi in 2012. In this paper, we calculate the Zagreb indices and the multiplicative versions of the Zagreb indices of an infinite class of Titania nanotubes TiO(2)[m,n].

  7. Carrier recombination dynamics in anatase TiO 2 nanoparticles

    Science.gov (United States)

    Cavigli, Lucia; Bogani, Franco; Vinattieri, Anna; Cortese, Lorenzo; Colocci, Marcello; Faso, Valentina; Baldi, Giovanni

    2010-11-01

    We present an experimental study of the radiative recombination dynamics in size-controlled TiO 2 nanoparticles in the range 20-130 nm. Time-integrated photoluminescence spectra clearly show a dominance of self-trapped exciton (STE) emission, with main features not dependent on the nanoparticle size and on its environment. From picosecond time-resolved experiments as a function of the excitation density and the nanoparticle size we address the STE recombination dynamics as the result of two main processes related to the direct STE formation and to the indirect STE formation mediated by non-radiative surface states.

  8. Al-bound hole polarons in TiO2

    International Nuclear Information System (INIS)

    Stashans, Arvids; Bermeo, Sthefano

    2009-01-01

    Changes in the structural and electronic properties of TiO 2 (anatase and rutile) due to the Al-doping are studied using a quantum-chemical approach based on the Hartree-Fock theory. The formation of hole polarons trapped at oxygen sites near the Al impurity has been discovered and their spatial configuration are discussed. The occurrence of well-localized one-center hole polarons in rutile may influence its photocatalytic activity. Optical absorption energy for this hole center is obtained, 0.4 eV, using the ΔSCF approach.

  9. Tailoring the wettability of nanocrystalline TiO 2 films

    Science.gov (United States)

    Liang, Qiyu; Chen, Yan; Fan, Yuzun; Hu, Yong; Wu, Yuedong; Zhao, Ziqiang; Meng, Qingbo

    2012-01-01

    The water contact angle (WCA) of nanocrystalline TiO2 films was adjusted by fluoroalkylsilane (FAS) modification and photocatalytic lithography. FAS modification made the surface hydrophobic with the WCA up to ∼156°, while ultraviolet (UV) irradiation changed surface to hydrophilic with the WCA down to ∼0°. Both the hydrophobicity and hydrophilicity were enhanced by surface roughness. The wettability can be tailored by varying the concentration of FAS solution and soaking time, as well as the UV light intensity and irradiation time. Additionally, with the help of photomasks, hydrophobic-hydrophilic micropatterns can be fabricated and manifested via area-selective deposition of polystyrene particles.

  10. Highly uniform bipolar resistive switching characteristics in TiO2/BaTiO3/TiO2 multilayer

    International Nuclear Information System (INIS)

    Ma, W. J.; Zhang, X. Y.; Wang, Ying; Zheng, Yue; Lin, S. P.; Luo, J. M.; Wang, B.; Li, Z. X.

    2013-01-01

    Nanoscale multilayer structure TiO 2 /BaTiO 3 /TiO 2 has been fabricated on Pt/Ti/SiO 2 /Si substrate by chemical solution deposition method. Highly uniform bipolar resistive switching (BRS) characteristics have been observed in Pt/TiO 2 /BaTiO 3 /TiO 2 /Pt cells. Analysis of the current-voltage relationship demonstrates that the space-charge-limited current conduction controlled by the localized oxygen vacancies should be important to the resistive switching behavior. X-ray photoelectron spectroscopy results indicated that oxygen vacancies in TiO 2 play a crucial role in the resistive switching phenomenon and the introduced TiO 2 /BaTiO 3 interfaces result in the high uniformity of bipolar resistive switching characteristics

  11. Synthesis of Fe2O3/TiO2 nanorod-nanotube arrays by filling TiO2 nanotubes with Fe

    International Nuclear Information System (INIS)

    Mohapatra, Susanta K; Banerjee, Subarna; Misra, Mano

    2008-01-01

    Synthesis of hematite (α-Fe 2 O 3 ) nanostructures on a titania (TiO 2 ) nanotubular template is carried out using a pulsed electrodeposition technique. The TiO 2 nanotubes are prepared by the sonoelectrochemical anodization method and are filled with iron (Fe) by pulsed electrodeposition. The Fe/TiO 2 composite is then annealed in an O 2 atmosphere to convert it to Fe 2 O 3 /TiO 2 nanorod-nanotube arrays. The length of the Fe 2 O 3 inside the TiO 2 nanotubes can be tuned from 50 to 550 nm by changing the deposition time. The composite material is characterized by scanning electron microscopy, transmission electron microscopy and diffuse reflectance ultraviolet-visible studies to confirm the formation of one-dimensional Fe 2 O 3 /TiO 2 nanorod-nanotube arrays. The present approach can be used for designing variable one-dimensional metal oxide heterostructures

  12. Komposit Nano TiO2 Dengan PCC, Zeolit atau Karbon Aktif Untuk Menurunkan Total Krom dan Zat Organik Pada Air Limbah Industri Penyamakan Kulit

    Directory of Open Access Journals (Sweden)

    Bumiarto Nugroho Jati

    2012-04-01

    Full Text Available Telah dilakukan penelitian untuk menurunkan total krom dan zat organik pada limbah industri penyamakan kulit dengan menggunakan nano TiO2 yang dikompositkan dengan adsorben karbon aktif, zeolit, dan precipitated calcium carbonate (PCC dalam suatu reaktor fotokatalitik yang disusun secara batch dan dilengkapi dengan 6 buah lampu UV dan magnetic stirrer. Penurunan kadar krom total diukur dengan menggunakan Atomic Absorption Spectro-photometer (AAS dan penurunan zat organik dianalisa dengan menggunakan titrasi permanganatometri. Hasil penelitian menunjukkan pengolahan terbaik untuk penurunan kadar krom total adalah dengan menggunakan komposit TiO2:PCC = 8:2 yang dapat menurunkan total krom hampir 100% pada menit ke-170 dengan konsentrasi awal 214,35 mg/L. Untuk penurunan kadar zat organik, pengolahan terbaik dengan menggunakan komposit TiO2:PCC = 9:1 yang dapat menurunkan kadar zat organik hingga 100% pada menit ke-180. 

  13. Magnetic properties of zigzag (0,9 GaAs nanotube doped with 3d transition metals

    Directory of Open Access Journals (Sweden)

    R Fathi

    2016-06-01

    Full Text Available of 3d transition metals (Sc, Ti, Cr, Mn , Fe, Co, Ni in both far and close situations were studied based on spin polarised density functional theory using the generalized gradient approximation (LDA with SIESTA code. The electronic structures show that zigzag (0,9 GaAs nanotubes are non-magnetic semiconductors with direct band gap. It was revealed that doping of 11.11 % Fe and Mn concentrations substituted in Ga sites in ferromagnetic phase in far situation and Cr sites in ferromagnetic phase in near situation introduces half metallic behavior with %100 spin polarization. The unique structure of spin polarised energy levels is primarily attributed to strong hybridization of 3d transition metal and its nearest-neighbor As-4p orbitals. The results of this study can be useful for empirical studies on diluted magnetic semiconductors (DMSs and systemic investigation in 3d transitional metals. We suggest that GaAs nanotubes doped by transition metals would have a potential application as a spin polarised electron source for spintronic devices in the future.

  14. Photocatalytic activities of heterostructured TiO2-graphene porous microspheres prepared by ultrasonic spray pyrolysis

    International Nuclear Information System (INIS)

    Yang, Jikai; Zhang, Xintong; Li, Bing; Liu, Hong; Sun, Panpan; Wang, Changhua; Wang, Lingling; Liu, Yichun

    2014-01-01

    Highlights: • USP method is used to prepare TiO 2 -graphene porous microspheres. • XPS shows GO sheets in the composites has been reduced to graphene. • TiO 2 -graphene microspheres display a red-shifted absorption edge. • PL spectra indicate graphene can accept the photoexcited electrons from TiO 2 . • TiO 2 -graphene shows higher photocatalytic activity than TiO 2 under solar light. -- Abstract: TiO 2 -graphene porous microspheres were prepared by ultrasonic spray pyrolysis (USP) of aqueous suspension of graphene oxide containing TiO 2 nanoparticles (Degussa P25). The composite microspheres were characterized with SEM, XPS, photoluminescence, Raman and UV–Vis absorption spectra. TiO 2 -graphene porous microspheres displayed higher photocatalytic activity for the degradation of methylene blue solution than pristine TiO 2 microspheres under the irradiation of Xe lamp, and the highest activity was obtained at a weight percentage of graphene around 1%. The effect of graphene on photocatalytic activity of porous microsphere was discussed in terms of the enhanced charge separation by TiO 2 -graphene heterojunction, increased absorption of the visible light, as well as the possible hindrance of mass transportation in microspheres

  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. 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

  18. Preparation of rutile TiO(2) coating by thermal chemical vapor deposition for anticoking applications.

    Science.gov (United States)

    Tang, Shiyun; Wang, Jianli; Zhu, Quan; Chen, Yaoqiang; Li, Xiangyuan

    2014-10-08

    To inhibit the metal catalytic coking and improve the oxidation resistance of TiN coating, rutile TiO2 coating has been directly designed as an efficient anticoking coating for n-hexane pyrolysis. TiO2 coatings were prepared on the inner surface of SS304 tubes by a thermal CVD method under varied temperatures from 650 to 900 °C. The rutile TiO2 coating was obtained by annealing the as-deposited TiO2 coating, which is an alternative route for the deposition of rutile TiO2 coating. The morphology, elemental and phase composition of TiO2 coatings were characterized by SEM, EDX and XRD, respectively. The results show that deposition temperature of TiO2 coatings has a strong effect on the morphology and thickness of as-deposited TiO2 coatings. Fe, Cr and Ni at.% of the substrate gradually changes to 0 when the temperature is increased to 800 °C. The thickness of TiO2 coating is more than 6 μm and uniform by metalloscopy, and the films have a nonstoichiometric composition of Ti3O8 when the deposition temperature is above 800 °C. The anticoking tests show that the TiO2 coating at a deposition temperature of 800 °C is sufficiently thick to cover the cracks and gaps on the surface of blank substrate and cut off the catalytic coke growth effect of the metal substrate. The anticoking ratio of TiO2 coating corresponding to each 5 cm segments is above 65% and the average anticoking ratio of TiO2 coating is up to 76%. Thus, the TiO2 coating can provide a very good protective layer to prevent the substrate from severe coking efficiently.

  19. 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.

  20. Microwave-assisted self-doping of TiO2 photonic crystals for efficient photoelectrochemical water splitting

    KAUST Repository

    Zhang, Zhonghai; Yang, Xiulin; Hedhili, Mohamed N.; Ahmed, Elaf S.; Shi, Le; Wang, Peng

    2014-01-01

    In this article, we report that the combination of microwave heating and ethylene glycol, a mild reducing agent, can induce Ti3+ self-doping in TiO2. A hierarchical TiO2 nanotube array with the top layer serving as TiO2 photonic crystals (TiO2 NTPCs

  1. Photoluminescence studies on Eu doped TiO2 nanoparticles

    International Nuclear Information System (INIS)

    Ningthoujam, R.S.; Sudarsan, V.; Vatsa, R.K.; Kadam, R.M.; Jagannath; Gupta, A.

    2009-01-01

    Eu 3+ doped TiO 2 nanoparticles were prepared by urea hydrolysis in ethylene glycol medium at low temperature of 150 deg. C. X-ray diffraction study showed that anatase phase of tetragonal structure was formed below 500 deg. C; and above this temperature, additional peaks due to rutile phase were also observed. From luminescence study, it was found that as prepared nanoparticles showed the enhanced luminescence intensity due to energy transfer from host to europium ions. However, photoluminescence from these nanoparticles was found to disappear when the samples were heated above 900 deg. C. We established the origin of the reduction in the luminescence intensity from Eu 3+ when doped in TiO 2 and heated at 900 deg. C. Based on detailed studies at different heat-treatment temperatures using techniques such as X-ray diffraction, X-ray photoelectron spectroscopy, electron paramagnetic resonance, Raman spectroscopy, and Moessbauer spectroscopy, it has been established that formation of Eu 2 Ti 2 O 7 phase, wherein Eu 3+ ions occupy high symmetric environment (D 3d ) and also reduced distance between Eu 3+ and Eu 3+ ions is responsible for the decrease/loss in the luminescence intensity.

  2. Unconventional cells of TiO2 doped with erbium

    International Nuclear Information System (INIS)

    Ribeiro, P.C.; Campos, R.D.; Oliveira, A.S.; Wellen, R.; Diniz, V.C.S.; Costa, A.C.F.M. da

    2016-01-01

    The technology used in TiO_2 solar cells is in constant improvement, new configurations have been developed, aiming practicality and leading to efficiency increase of photovoltaic devices. This paper proposes a new technology for the production of solar cells in order to investigate a better utilization of solar spectrum of TiO2 doped with erbium (Er"3"+), proven by energetic conversion. The Ti_0_,_9Er_0_,_1O2 system was obtained by Pechini method. Nanoparticles have a crystallite size 65.30 nm and surface area 118.48 m"2/g. These characteristics are essential for the formation of the film to be deposited on the conductive glass substrate constituting the cell's photoelectrode. The other side of the cell is the platinum counter electrode. The cell will have the faces sealed by a thermoplastic and, finally the electrolyte will be inserted, then they will be electrically evaluated through energy efficiency and confronted with the literature data base. (author)

  3. Fabrication and characterization of TiO2-epoxy nanocomposite

    International Nuclear Information System (INIS)

    Chatterjee, Amit; Islam, Muhammad S.

    2008-01-01

    A systematic study has been conducted to investigate the matrix properties by introducing nanosize TiO 2 (5-40 nm, 0.5-2% by weight) fillers into an epoxy resin. Ultrasonic mixing process, via sonic cavitations, was employed to disperse the particles into the resin system. The thermal, mechanical, morphology and the viscoelastic properties of the nanocomposite and the neat resin were measured with TGA, DMA, TEM and Instron. The nano-particles are dispersed evenly throughout the entire volume of the resin. The nanofiller infusion improves the thermal, mechanical and viscoelastic properties of the epoxy resin. The nanocomposite shows increase in storage modulus, glass transition temperature, tensile modulus, flexural modulus and short beam shear strength from neat epoxy resin. The mechanical performance and thermal stability of the epoxy nanocomposites are depending on with the dispersion state of the TiO 2 in the epoxy matrix and are correlated with loading (0.0015-0.006% by volume). In addition, the nanocomposite shows enhanced flexural strength. Several reasons to explain these effects in terms of reinforcing mechanisms were discussed

  4. 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

  5. Surface and interface engineering of anatase TiO2 anode for sodium-ion batteries through Al2O3 surface modification and wise electrolyte selection

    Science.gov (United States)

    Li, Tao; Gulzar, Umair; Bai, Xue; Monaco, Simone; Longoni, Gianluca; Prato, Mirko; Marras, Sergio; Dang, Zhiya; Capiglia, Claudio; Proietti Zaccaria, Remo

    2018-04-01

    In the present study, Al2O3 is utilized for the first time as coating agent on nanostructured anatase TiO2 in order to investigate its effect on sodium-ion batteries performance. Our results show that the Al2O3 coating, introduced by a facile two-step approach, provides beneficial effects to the TiO2-based anodes. However, the coated TiO2 still suffers of capacity fading upon cycling when using 1.0 M of NaClO4 in propylene carbonate (PC) as electrolyte. To address this issue, the influence of different electrolytes (NaClO4 salt in various solvents) is further studied. It is found that the modified TiO2 exhibits significant improvements in cycling performance using binary ethylene carbonate (EC) and PC solvent mixture without the need of the commonly used fluoroethylene carbonate (FEC) additive. Under the best configuration, our battery could deliver a high reversible capacity of 188.1 mAh g-1 at 0.1C after 50 cycles, good rate capability up to 5C, and remarkable long-term cycling stability at 1C rate for 650 cycles. This excellent performance can be ascribed to the synergistic effects of surface and interface engineering enabling the formation of a stable and highly ionic conductive interface layer in EC:PC based electrolyte which combines the native SEI film and an 'artificial' SEI layer of irreversibly formed Na-Al-O.

  6. Particle emission rates during electrostatic spray deposition of TiO2 nanoparticle-based photoactive coating.

    Science.gov (United States)

    Koivisto, Antti J; Jensen, Alexander C Ø; Kling, Kirsten I; Kling, Jens; Budtz, Hans Christian; Koponen, Ismo K; Tuinman, Ilse; Hussein, Tareq; Jensen, Keld A; Nørgaard, Asger; Levin, Marcus

    2018-01-05

    Here, we studied the particle release rate during Electrostatic spray deposition of anatase-(TiO 2 )-based photoactive coating onto tiles and wallpaper using a commercially available electrostatic spray device. Spraying was performed in a 20.3m 3 test chamber while measuring concentrations of 5.6nm to 31μm-size particles and volatile organic compounds (VOC), as well as particle deposition onto room surfaces and on the spray gun user hand. The particle emission and deposition rates were quantified using aerosol mass balance modelling. The geometric mean particle number emission rate was 1.9×10 10 s -1 and the mean mass emission rate was 381μgs -1 . The respirable mass emission-rate was 65% lower than observed for the entire measured size-range. The mass emission rates were linearly scalable (±ca. 20%) to the process duration. The particle deposition rates were up to 15h -1 for deposited particles consisted of mainly TiO 2 , TiO 2 mixed with Cl and/or Ag, TiO 2 particles coated with carbon, and Ag particles with size ranging from 60nm to ca. 5μm. As expected, no significant VOC emissions were observed as a result of spraying. Finally, we provide recommendations for exposure model parameterization. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

  7. 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.

  8. Optimization of photoelectrochemical water splitting performance on hierarchical TiO 2 nanotube arrays

    KAUST Repository

    Zhang, Z.; Wang, Peng

    2012-01-01

    In this paper, we show that by varying the voltages during two-step anodization the morphology of the hierarchical top-layer/bottom-tube TiO 2 (TiO 2 NTs) can be finely tuned between nanoring/nanotube, nanopore/nanotube, and nanohole-nanocave/nanotube morphologies. This allows us to optimize the photoelectrochemical (PEC) water splitting performance on the hierarchical TiO 2 NTs. The optimized photocurrent density and photoconversion efficiency in this study, occurring on the nanopore/nanotube TiO 2 NTs, were 1.59 mA cm -2 at 1.23 V vs. RHE and 0.84% respectively, which are the highest values ever reported on pristine TiO 2 materials under illumination of AM 1.5G. Our findings contribute to further improvement of the energy conversion efficiency of TiO 2-based devices.

  9. Reflectance spectroscopy from TiO2 particles embedded in polyurethane

    DEFF Research Database (Denmark)

    Gudla, Visweswara Chakravarthy; Canulescu, Stela; Johansen, Villads Egede

    2013-01-01

    This paper presents the results of a physical simulation carried out using TiO2-Polyurethane composite coating on bright aluminium surface to understand the light scattering effect for designing white surfaces. Polyurethane matrix is selected due to the matching refractive index (1.7) with Al2O3...... layer on anodized aluminium surfaces. Three different TiO2 particle distributions were dispersed in polyurethane and spin coated onto high gloss and caustic etched aluminium substrates. Reflectance spectra of TiO2-polyurethane films of various concentrations were analysed using an integrating sphere....... The results show that the TiO2-polyurethane coatings have a high diffuse reflectance as a result of multiple scattering from TiO2 particles. Diffuse reflectance spectra of TiO2 containing films vary weakly with particle concentration and reach a steady state value at a concentration of 0.75 wt.%. Using...

  10. 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)

  11. Optimization of photoelectrochemical water splitting performance on hierarchical TiO 2 nanotube arrays

    KAUST Repository

    Zhang, Z.

    2012-02-10

    In this paper, we show that by varying the voltages during two-step anodization the morphology of the hierarchical top-layer/bottom-tube TiO 2 (TiO 2 NTs) can be finely tuned between nanoring/nanotube, nanopore/nanotube, and nanohole-nanocave/nanotube morphologies. This allows us to optimize the photoelectrochemical (PEC) water splitting performance on the hierarchical TiO 2 NTs. The optimized photocurrent density and photoconversion efficiency in this study, occurring on the nanopore/nanotube TiO 2 NTs, were 1.59 mA cm -2 at 1.23 V vs. RHE and 0.84% respectively, which are the highest values ever reported on pristine TiO 2 materials under illumination of AM 1.5G. Our findings contribute to further improvement of the energy conversion efficiency of TiO 2-based devices.

  12. Engineering of highly ordered TiO2 nanopore arrays by anodization

    Science.gov (United States)

    Wang, Huijie; Huang, Zhennan; Zhang, Li; Ding, Jie; Ma, Zhaoxia; Liu, Yong; Kou, Shengzhong; Yang, Hangsheng

    2016-07-01

    Finite element analysis was used to simulate the current density distributions in the TiO2 barrier layer formed at the initial stage of Ti anodization. The morphology modification of the barrier layer was found to induce current density distribution change. By starting the anodization with proper TiO2 barrier layer morphology, the current density distribution can be adjusted to favor the formation of either nanotube arrays or nanopore arrays of anodic TiO2. We also found that the addition of sodium acetate into the electrolyte suppressed both the field-assisted chemical dissolution of TiO2 and the TiF62- hydrolysis induced TiO2 deposition during anodization, and thus further favored the nanopore formation. Accordingly, highly ordered anodic TiO2 nanopore arrays, similar to anodic aluminum oxide nanopore arrays, were successfully prepared.

  13. 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

  14. Effect of surface ethoxy groups on photoactivity of TiO2 nanocrystals

    International Nuclear Information System (INIS)

    Tian Lihong; Deng Kejian; Ye Liqun; Zan Lin

    2011-01-01

    TiO 2 nanocrystals modified by ethoxy groups were prepared by a facile nonhydrolytic solvothermal method and characterized by XRD, TEM, TG-DTA and XPS, which showed an enhanced visible-light photocatalytic activity on the degradation of Rhodamine B compared with TiO 2 modified by benzyloxy groups and the 'naked' TiO 2 . The adsorption and degradation pathway of Rhodamine B on TiO 2 modified by ethoxy groups were also investigated. The zeta-potential (ζ) results showed that the TiO 2 modified by ethoxy groups had high negative surface charge, which incited the positive -N(Et) 2 group of RhB absorbing on the TiO 2 surface and preferably led the N-dealkylation pathway under visible light irradiation.

  15. 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.

  16. Graphene-enhanced Raman imaging of TiO2 nanoparticles

    International Nuclear Information System (INIS)

    Naumenko, Denys; Snitka, Valentinas; Snopok, Boris; Arpiainen, Sanna; Lipsanen, Harri

    2012-01-01

    The interaction of anatase titanium dioxide (TiO 2 ) nanoparticles with chemical vapour deposited graphene sheets transferred on glass substrates is investigated by using atomic force microscopy, Raman spectroscopy and imaging. Significant electronic interactions between the nanoparticles of TiO 2 and graphene were found. The changes in the graphene Raman peak positions and intensity ratios indicate that charge transfer between graphene and TiO 2 nanoparticles occurred, increasing the Raman signal of the TiO 2 nanoparticles up to five times. The normalized Raman intensity of TiO 2 nanoparticles per their volume increased with the disorder of the graphene structure. The complementary reason for the observed enhancement is that due to the higher density of states in the defect sites of graphene, a higher electron transfer occurs from the graphene to the anatase TiO 2 nanoparticles. (paper)

  17. Enhanced photoelectrochemical and photocatalytic activity of WO3-surface modified TiO2 thin film

    Science.gov (United States)

    Qamar, Mohammad; Drmosh, Qasem; Ahmed, Muhammad I.; Qamaruddin, Muhammad; Yamani, Zain H.

    2015-02-01

    Development of nanostructured photocatalysts for harnessing solar energy in energy-efficient and environmentally benign way remains an important area of research. Pure and WO3-surface modified thin films of TiO2 were prepared by magnetron sputtering on indium tin oxide glass, and photoelectrochemical and photocatalytic activities of these films were studied. TiO2 particles were <50 nm, while deposited WO3 particles were <20 nm in size. An enhancement in the photocurrent was observed when the TiO2 surface was modified WO3 nanoparticles. Effect of potential, WO3 amount, and radiations of different wavelengths on the photoelectrochemical activity of TiO2 electrodes was investigated. Photocatalytic activity of TiO2 and WO3-modified TiO2 for the decolorization of methyl orange was tested.

  18. 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.

  19. Ammonia Sensing Behaviors of TiO2-PANI/PA6 Composite Nanofibers

    Directory of Open Access Journals (Sweden)

    Fenglin Huang

    2012-12-01

    Full Text Available Titanium dioxide-polyaniline/polyamide 6 (TiO2-PANI/PA6 composite nanofibers were prepared by in situ polymerization of aniline in the presence of PA6 nanofibers and a sputtering-deposition process with a high purity titanium sputtering target. TiO2-PANI/PA6 composite nanofibers and PANI/PA6 composite nanofibers were fabricated for ammonia gas sensing. The ammonia sensing behaviors of the sensors were examined at room temperature. All the results indicated that the ammonia sensing property of TiO2-PANI/PA6 composite nanofibers was superior to that of PANI/PA6 composite nanofibers. TiO2-PANI/PA6 composite nanofibers had good selectivity to ammonia. It was also found that the content of TiO2 had a great influence on both the morphology and the sensing property of TiO2-PANI/PA6 composite nanofibers.

  20. 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.

  1. TiO2 nanofiber solid-state dye sensitized solar cells with thin TiO2 hole blocking layer prepared by atomic layer deposition

    International Nuclear Information System (INIS)

    Li, Jinwei; Chen, Xi; Xu, Weihe; Nam, Chang-Yong; Shi, Yong

    2013-01-01

    We incorporated a thin but structurally dense TiO 2 layer prepared by atomic layer deposition (ALD) as an efficient hole blocking layer in the TiO 2 nanofiber based solid-state dye sensitized solar cell (ss-DSSC). The nanofiber ss-DSSCs having ALD TiO 2 layers displayed increased open circuit voltage, short circuit current density, and power conversion efficiency compared to control devices with blocking layers prepared by spin-coating liquid TiO 2 precursor. We attribute the improved photovoltaic device performance to the structural integrity of ALD-coated TiO 2 layer and consequently enhanced hole blocking effect that results in reduced dark leakage current and increased charge carrier lifetime. - Highlights: • TiO 2 blocking locking layer prepared by atomic layer deposition (ALD) method. • ALD-coated TiO 2 layer enhanced hole blocking effect. • ALD blocking layer improved the voltage, current and efficiency. • ALD blocking layer reduced dark leakage current and increased electron lifetime

  2. 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.

  3. Characterization of manufactured TiO2 nanoparticles

    Science.gov (United States)

    Motzkus, C.; Macé, T.; Vaslin-Reimann, S.; Ausset, P.; Maillé, M.

    2013-04-01

    Technological advances in nanomaterials have allowed the development of new applications in industry, increasing the probability of finding airborne manufactured and engineered nano-objects in the workplace, as well as in ambient air. Scientific studies on health and environmental risks have indicated that airborne nano-objects in ambient air have potential adverse effects on the health of exposed workers and the general population. For regulatory purposes, ambient measurements of particulate matter are based on the determination of mass concentrations for PM10 and PM2.5, as regulated in the European Directive 2008/50/EC. However, this legislation is not suitable for airborne manufactured and engineered nano-objects. Parameters characterising ultrafine particles, such as particle number concentration and size distribution, are under consideration for future health-based legislation, to monitor workplaces and to control industrial processes. Currently, there are no existing regulations covering manufactured airborne nano-objects. There is therefore a clear, unaddressed need to focus on the toxicology and exposure assessment of nano-objects such as titanium dioxide (TiO2), which are manufactured and engineered in large quantities in industry. To perform reliable toxicology studies it is necessary to determine the relevant characteristics of nano-objects, such as morphology, surface area, agglomeration, chemical composition, particle size and concentration, by applying traceable methods. Manufacturing of nanomaterials, and their use in industrial applications, also require traceable characterisation of the nanomaterials, particularly for quality control of the process. The present study arises from the OECD WPMN sponsorship programme, supported by the French Agency for Environmental and Occupational Health Safety (ANSES), in order to develop analytical methods for the characterization of TiO2 nanoparticles in size and count size distribution, based on different techniques to characterize five different manufactured TiO2 nanoparticles. In this study, different measurement techniques have been implemented: Transmission Electron Microscopy (TEM), Scanning Mobility Particle Sizer (SMPS) and Aerodynamic Particle Sizer (APS). The TEM results lead to a relatively good agreement between data from the manufacturer and our characterizations of primary particle size. With regard to the dustiness, the results show a strong presence of agglomerates / aggregates of primary particles and a significant presence of emitted airborne nanoparticles with a diameter below 100 nm (composed of isolated primary particles and small aggregates / agglomerates formed from a few primary particles): the number proportion of these particles varies from 0 to 44 % in the measurement range 14-360 nm depending on the types of powders and corrections of measurements.

  4. Characterization of manufactured TiO2 nanoparticles

    International Nuclear Information System (INIS)

    Motzkus, C; Macé, T; Vaslin-Reimann, S; Ausset, P; Maillé, M

    2013-01-01

    Technological advances in nanomaterials have allowed the development of new applications in industry, increasing the probability of finding airborne manufactured and engineered nano-objects in the workplace, as well as in ambient air. Scientific studies on health and environmental risks have indicated that airborne nano-objects in ambient air have potential adverse effects on the health of exposed workers and the general population. For regulatory purposes, ambient measurements of particulate matter are based on the determination of mass concentrations for PM10 and PM2.5, as regulated in the European Directive 2008/50/EC. However, this legislation is not suitable for airborne manufactured and engineered nano-objects. Parameters characterising ultrafine particles, such as particle number concentration and size distribution, are under consideration for future health-based legislation, to monitor workplaces and to control industrial processes. Currently, there are no existing regulations covering manufactured airborne nano-objects. There is therefore a clear, unaddressed need to focus on the toxicology and exposure assessment of nano-objects such as titanium dioxide (TiO 2 ), which are manufactured and engineered in large quantities in industry. To perform reliable toxicology studies it is necessary to determine the relevant characteristics of nano-objects, such as morphology, surface area, agglomeration, chemical composition, particle size and concentration, by applying traceable methods. Manufacturing of nanomaterials, and their use in industrial applications, also require traceable characterisation of the nanomaterials, particularly for quality control of the process. The present study arises from the OECD WPMN sponsorship programme, supported by the French Agency for Environmental and Occupational Health Safety (ANSES), in order to develop analytical methods for the characterization of TiO 2 nanoparticles in size and count size distribution, based on different techniques to characterize five different manufactured TiO 2 nanoparticles. In this study, different measurement techniques have been implemented: Transmission Electron Microscopy (TEM), Scanning Mobility Particle Sizer (SMPS) and Aerodynamic Particle Sizer (APS). The TEM results lead to a relatively good agreement between data from the manufacturer and our characterizations of primary particle size. With regard to the dustiness, the results show a strong presence of agglomerates / aggregates of primary particles and a significant presence of emitted airborne nanoparticles with a diameter below 100 nm (composed of isolated primary particles and small aggregates / agglomerates formed from a few primary particles): the number proportion of these particles varies from 0 to 44 % in the measurement range 14-360 nm depending on the types of powders and corrections of measurements.

  5. Positron annihilation lifetime characterization of oxygen ion irradiated rutile TiO2

    Science.gov (United States)

    Luitel, Homnath; Sarkar, A.; Chakrabarti, Mahuya; Chattopadhyay, S.; Asokan, K.; Sanyal, D.

    2016-07-01

    Ferromagnetic ordering at room temperature has been induced in rutile phase of TiO2 polycrystalline sample by O ion irradiation. 96 MeV O ion induced defects in rutile TiO2 sample has been characterized by positron annihilation spectroscopic techniques. Positron annihilation results indicate the formation of cation vacancy (VTi, Ti vacancy) in these irradiated TiO2 samples. Ab initio density functional theoretical calculations indicate that in TiO2 magnetic moment can be induced either by creating Ti or O vacancies.

  6. The effects of nanostructures on the mechanical and tribological properties of TiO2 nanotubes

    Science.gov (United States)

    Yoon, Yeoungchin; Park, Jeongwon

    2018-04-01

    TiO2 nanotubes were prepared by anodization on Ti substrates with a diameter variation of 30-100 nm, and the structure of the nanotubes were studied using x-ray diffraction and Raman spectroscopy, which confirmed the structure changes from the anatase phase to the rutile phase of TiO2 at a diameter below 50 nm. The tribological behaviors of TiO2 nanotubes were investigated with different diameters. The effectiveness of the rutile phase and the diameter size enhanced the frictional performance of TiO2 nanotubes.

  7. Annealing of TiO2 Films Deposited on Si by Irradiating Nitrogen Ion Beams

    International Nuclear Information System (INIS)

    Yokota, Katsuhiro; Yano, Yoshinori; Miyashita, Fumiyoshi

    2006-01-01

    Thin TiO2 films were deposited on Si at a temperature of 600 deg. C by an ion beam assisted deposition (IBAD) method. The TiO2 films were annealed for 30 min in Ar at temperatures below 700 deg. C. The as-deposited TiO2 films had high permittivities such 200 εo and consisted of crystallites that were not preferentially oriented to the c-axis but had an expanded c-axis. On the annealed TiO2 films, permittivities became lower with increasing annealing temperature, and crystallites were oriented preferentially to the (110) plane

  8. 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.

  9. Defective TiO2 with oxygen vacancies: synthesis, properties and photocatalytic applications

    Science.gov (United States)

    Pan, Xiaoyang; Yang, Min-Quan; Fu, Xianzhi; Zhang, Nan; Xu, Yi-Jun

    2013-04-01

    Titanium dioxide (TiO2), as an important semiconductor metal oxide, has been widely investigated in the field of photocatalysis. The properties of TiO2, including its light absorption, charge transport and surface adsorption, are closely related to its defect disorder, which in turn plays a significant role in the photocatalytic performance of TiO2. Among all the defects identified in TiO2, oxygen vacancy is one of the most important and is supposed to be the prevalent defect in many metal oxides, which has been widely investigated both by theoretical calculations and experimental characterizations. Here, we give a short review on the existing strategies for the synthesis of defective TiO2 with oxygen vacancies, and the defect related properties of TiO2 including structural, electronic, optical, dissociative adsorption and reductive properties, which are intimately related to the photocatalytic performance of TiO2. In particular, photocatalytic applications with regard to defective TiO2 are outlined. In addition, we offer some perspectives on the challenge and new direction for future research in this field. We hope that this tutorial minireview would provide some useful contribution to the future design and fabrication of defective semiconductor-based nanomaterials for diverse photocatalytic applications.Titanium dioxide (TiO2), as an important semiconductor metal oxide, has been widely investigated in the field of photocatalysis. The properties of TiO2, including its light absorption, charge transport and surface adsorption, are closely related to its defect disorder, which in turn plays a significant role in the photocatalytic performance of TiO2. Among all the defects identified in TiO2, oxygen vacancy is one of the most important and is supposed to be the prevalent defect in many metal oxides, which has been widely investigated both by theoretical calculations and experimental characterizations. Here, we give a short review on the existing strategies for the synthesis of defective TiO2 with oxygen vacancies, and the defect related properties of TiO2 including structural, electronic, optical, dissociative adsorption and reductive properties, which are intimately related to the photocatalytic performance of TiO2. In particular, photocatalytic applications with regard to defective TiO2 are outlined. In addition, we offer some perspectives on the challenge and new direction for future research in this field. We hope that this tutorial minireview would provide some useful contribution to the future design and fabrication of defective semiconductor-based nanomaterials for diverse photocatalytic applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr00476g

  10. Enhancing lipid productivity of Chlorella vulgaris using oxidative stress by TiO2 nanoparticles

    International Nuclear Information System (INIS)

    Kang, Nam Kyu; Lee, Bongsoo; Choi, Gang-Guk; Moon, Myounghoon; Park, Min S.; Yang, Ji-Won; Lim, JitKang

    2014-01-01

    Ability to increase the lipid production in microalgae is one of the heavily sought-after ideas to improve the economic feasibility of microalgae-derived transportation fuels for commercial applications. We used the oxidative stress by TiO 2 nanoparticles, a well-known photocatalyst, to induce lipid production in microalgae. Chlorella vulgaris UTEX 265 was cultivated under various concentrations of TiO 2 ranging from 0.1 to 5 g/L under UV-A illumination. Maximum specific growth rate was affected in responding to TiO 2 concentrations. In the presence of UV-A, chlorophyll concentration was decreased at the highest concentration of TiO 2 (5 g/L TiO 2 ) by oxidative stress. The fatty acid methyl ester (FAME) composition analysis suggested that oxidative stress causes the accumulation and decomposition of lipids. The highest FAME productivity was 18.2 g/L/d under low concentrations of TiO 2 (0.1 g/L) and a short induction time (two days). The controlled condition of TiO 2 /UV-A inducing oxidative stress (0.1 g/L TiO 2 and two days induction) could be used to increase the lipid productivity of C. vulgaris UTEX 265. Our results show the possibility of modulating the lipid induction process through oxidative stress with TiO 2 /UV-A

  11. Preparation and characterization of nanocrystalline porous TiO2/WO3 composite thin films

    International Nuclear Information System (INIS)

    Hsu, C.-S.; Lin, C.-K.; Chan, C.-C.; Chang, C.-C.; Tsay, C.-Y.

    2006-01-01

    TiO 2 materials possessing not only photocatalytic but also electrochromic properties have attracted many research and development interests. Though WO 3 exhibits excellent electrochromic properties, the much higher cost and water-sensitivity of WO 3 as compared with the TiO 2 may restrict the practical application of WO 3 materials. In the present study, the feasibility of preparing nanocrystalline porous TiO 2 /WO 3 composite thin films was investigated. Precursors of sols TiO 2 and/or WO 3 and polystyrene microspheres were used to prepare nanocrystalline pure TiO 2 , WO 3 , and composite TiO 2 /WO 3 thin films by spin coating. The spin-coated thin films were amorphous and, after heat treating at a temperature of 500 o C, nanocrystalline TiO 2 , TiO 2 /WO 3 , and WO 3 thin films with or without pores were prepared successfully. The heat-treated thin films were colorless and coloration-bleaching phenomena can be observed during cyclic voltammetry tests. The heat-treated thin films exhibited good reversible electrochromic behavior while the porous TiO 2 /WO 3 composite film exhibited improved electrochromic properties

  12. 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.

  13. One-component solution system to prepare nanometric anatase TiO2

    International Nuclear Information System (INIS)

    Trung, Tran; Ha, Chang-Sik

    2004-01-01

    A novel one-pot synthesis route was proposed to prepare nanometric anatase TiO 2 using trichloroethylene as reaction medium, which may have great advantage over multicomponent solution systems when TiO 2 is used as a reinforcing filler for polymers dissolved in trichloroethylene. The anatase TiO 2 nanoparticles were characterized using X-ray diffraction (XRD), scanning electron microscopy and small-angle X-ray scattering (SAXS). It was found that the diameters of TiO 2 nanoparticles are in the range from 5 to 13 nm

  14. Photodecomposition of volatile organic compounds using TiO2 nanoparticles.

    Science.gov (United States)

    Jwo, Ching-Song; Chang, Ho; Kao, Mu-Jnug; Lin, Chi-Hsiang

    2007-06-01

    This study examined the photodecomposition of volatile organic compounds (VOCs) using TiO2 catalyst fabricated by the Submerged Arc Nanoparticle Synthesis System (SANSS). TiO2 catalyst was employed to decompose volatile organic compounds and compare with Degussa-P25 TiO2 in terms of decomposition efficiency. In the electric discharge manufacturing process, a Ti bar, applied as the electrode, was melted and vaporized under high temperature. The vaporized Ti powders were then rapidly quenched under low-temperature and low-pressure conditions in deionized water, thus nucleating and forming nanocrystalline powders uniformly dispersed in the base solvent. The average diameter of the TiO2 nanoparticles was 20 nm. X-ray diffraction analysis confirmed that the nanoparticles in the deionized water were Anatase type TiO2. It was found that gaseous toluene exposed to UV irradiation produced intermediates that were even harder to decompose. After 60-min photocomposition, Degussa-P25 TiO2 reduced the concentration of gaseous toluene to 8.18% while the concentration after decomposition by SANSS TiO2 catalyst dropped to 0.35%. Under UV irradiation at 253.7 +/- 184.9 nm, TiO2 prepared by SANSS can produce strong chemical debonding energy, thus showing great efficiency, superior to that of Degussa-P25 TiO2, in decomposing gaseous toluene and its intermediates.

  15. Degradation of Methyl Orange and Congo Red dyes by using TiO2 nanoparticles activated by the solar and the solar-like radiation.

    Science.gov (United States)

    Ljubas, Davor; Smoljanić, Goran; Juretić, Hrvoje

    2015-09-15

    In this study we used TiO2 nanoparticles as semiconductor photocatalysts for the degradation of Methyl Orange (MO) and Congo Red (CR) dyes in an aqueous solution. Since TiO2 particles become photocatalytically active by UV radiation, two sources of UV-A radiation were used - natural solar radiation which contains 3-5% UV-A and artificial, solar-like radiation, created by using a lamp. The optimal doses of TiO2 of 500 mg/L for the CR and 1500 mg/L for the MO degradation were determined in experiments with the lamp and were also used in degradation experiments with natural solar light. The efficiency of each process was determined by measuring the absorbance at two visible wavelengths, 466 nm for MO and 498 nm for CR, and the total organic carbon (TOC), i.e. decolorization and mineralization, respectively. In both cases, considerable potential for the degradation of CR and MO was observed - total decolorization of the solution was achieved within 30-60 min, while the TOC removal was in the range 60-90%. CR and MO solutions irradiated without TiO2 nanoparticles showed no observable changes in either decolorization or mineralization. Three different commercially available TiO2 nanoparticles were used: pure-phase anatase, pure-phase rutile, and mixed-phase preparation named Degussa P25. In terms of degradation kinetics, P25 TiO2 exhibited a photocatalytic activity superior to that of pure-phase anatase or rutile. The electric energy consumption per gram of removed TOC was determined. For nearly the same degradation effect, the consumption in the natural solar radiation experiment was more than 60 times lower than in the artificial solar-like radiation experiment. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. N-doped TiO2 photo-catalyst for the degradation of 1,2-dichloroethane under fluorescent light

    International Nuclear Information System (INIS)

    Lin, Yi-Hsing; Chiu, Tang-Chun; Hsueh, Hsin-Ta; Chu, Hsin

    2011-01-01

    The photo-catalytic degradation of 1,2-dichloroethane (1, 2-DCE) using nitrogen-doped TiO 2 photo-catalysts under fluorescent light irradiation was investigated. Highly pure TiO 2 and nitrogen-doped TiO 2 were prepared by a sol-gel method and characterized by thermo-gravimetric/differential-thermal analysis (TG/DTA), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy. The results indicate that the photo-catalysts were mainly nano-size with an anatase-phase structure. The degradation reaction of 1,2-DCE was operated under visible-light irradiation, and the photo-catalytic oxidation was conducted in a batch photo-reactor with various nitrogen doping ratios (N/Ti = 0-25 mol%). The relative humidity (RH) was controlled at 0-20% and the oxygen concentration was controlled at 0-21%. The photo-degradation with nitrogen-doped TiO 2 showed superior photo-catalytic activity compared to that for pure TiO 2 . TiO 2 doped with 15 mol% nitrogen exhibited the best photo-catalytic efficiency under the tested conditions. The products from the 1,2-DCE photo-catalytic oxidation were CO 2 and water; the by-products included dichloromethane, methyl chloride, ethyl chloride, carbon monoxide, and hydrogen chloride. The reaction pathway of 1,2-DCE indicates that oxygen molecules are the major factor that causes the degradation of 1,2-DCE in the gas phase.

  17. 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...

  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 photocatalytic results showed that the Ag nanoparticle modified TiO 2 NTs largely enhanced the photocatalytic degradation of methyl orange under ultraviolet light irradiation.

  19. The Effects of Anchor Groups on (1) TiO2-Catalyzed Photooxidation and (2) Linker-Assisted Assembly on TiO2

    Science.gov (United States)

    Anderson, Ian Mark

    Quantum dot-sensitized solar cells (QDSSCs) are a popular target for research due to their potential for highly efficient, easily tuned absorption. Typically, light is absorbed by quantum dots attached to a semiconductor substrate, such as TiO2, via bifunctional linker molecules. This research aims to create a patterned monolayer of linker molecules on a TiO2 film, which would in turn allow the attachment of a patterned layer of quantum dots. One method for the creation of a patterned monolayer is the functionalization of a TiO2 film with a linker molecule, followed by illumination with a laser at 355 nm. This initiates a TiO 2-catalyzed oxidation reaction, causing loss of surface coverage. A second linker molecule can then be adsorbed onto the TiO2 surface in the illuminated area. Towards that end, the behaviors of carboxylic and phosphonic acids adsorbed on TiO2 have been studied. TiO2 films were functionalized by immersion in solutions a single adsorbate and surface coverage was determined by IR spectroscopy. It is shown that phosphonic acids attain higher surface coverage than carboxylic acids, and will displace them from TiO2 when in a polar solvent. Alkyl chain lengths, which can influence stabilities of monolayers, are shown not to have an effect on this relationship. Equilibrium binding data for the adsorption of n-hexadecanoic acid to TiO2 from a THF solution are presented. It is shown that solvent polarity can affect monolayer stability; carboxylates and phosphonates undergo more desorption into polar solvents than nonpolar. Through illumination, it was possible to remove nearly all adsorbed linkers from TiO2. However, the illuminated areas were found not to be receptive to attachment by a second adsorbate. A possible reason for this behavior is presented. I also report on the synthesis and characterization of a straight-chain, thiol-terminated phosphonic acid. Initial experiments involving monolayer formation and quantum dot attachment are presented. Finally, it was found that quantum dots attach in high amounts to linker-functionalized TiO2 when suspended in pyridine. This increased surface attachment was present even when the linker molecule used lacked a functional group which would bind to the CdSe surface.

  20. The synthesis of aqueous-dispersible anatase TiO2 nanoplatelets

    International Nuclear Information System (INIS)

    Shan Guobin; Demopoulos, George P

    2010-01-01

    Aqueous well-dispersed and phase-pure anatase TiO 2 truncated octahedron nanoplatelets (NPLs) were prepared via controlled hydrolysis of titanium tetrachloride (TiCl 4 ) in ethylene glycol at 240 deg. C. Two shapes, square and hexagon, were observed by microscopy, exactly corresponding to the truncated octahedron NPLs. Ethylene glycol was found to produce water in situ that reacts with TiCl 4 to produce TiO 2 and HCl-the latter promoting TiO 2 colloid peptization. TiO 2 truncated octahedron NPLs are formed under the stabilizing action of ethylene glycol thermolysis derivatives, such as aldehydes. Crystal growth of the TiO 2 NPLs was affected by the reaction temperature that determines the water production rate and HCl-assisted peptization. TGA and FT-IR results showed ∼1.2% ethylene glycol thermolysis derivatives are attached to the surface of the TiO 2 NPLs, which prevents their agglomeration, hence making them easily dispersible in aqueous media. HR-TEM and SAED results showed that the TiO 2 NPLs are well crystallized and that the SAED patterns of the single TiO 2 NPL changes with its size and shape. XRD patterns showed that the TiO 2 NPLs are phase-pure anatase and the percentage of the {101} plane in the TiO 2 NPLs to be only 18%-a structural feature that renders the TiO 2 NPLs with enhanced UV absorption and reactivity properties.

  1. 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%.

  2. Rapid detection of TiO2 (E171) in table sugar using Raman spectroscopy.

    Science.gov (United States)

    Tan, Chen; Zhao, Bin; Zhang, Zhiyun; He, Lili

    2017-02-01

    The potential toxic effects of titanium dioxide (TiO 2 ) to humans remain debatable despite its broad application as a food additive. Thus, confirmation of the existence of TiO 2 particles in food matrices and subsequently quantifying them are becoming increasingly critical. This study developed a facile, rapid (E171) from food products (e.g., table sugar) by Raman spectroscopy. To detect TiO 2 particles from sugar solution, sequential centrifugation and washing procedures were effectively applied to separate and recover 97% of TiO 2 particles from the sugar solution. The peak intensity of TiO 2 sensitively responded to the concentration of TiO 2 with a limit of detection (LOD) of 0.073 mg kg -1 . In the case of sugar granules, a mapping technique was applied to directly estimate the level of TiO 2 , which can be potentially used for rapid online monitoring. The plot of averaged intensity to TiO 2 concentration in the sugar granules exhibited a good linear relationship in the wide range of 5-2000 mg kg -1 , with an LOD of 8.46 mg kg -1 . Additionally, we applied Raman spectroscopy to prove the presence of TiO 2 in sugar-coated doughnuts. This study begins to fill in the analytical gaps that exist regarding the rapid detection and quantification of TiO 2 in food, which facilitate the risk assessment of TiO 2 through food exposure.

  3. 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

  4. Direct Visualization of 2-Butanol Adsorption and Dissociation on TiO2(110)

    International Nuclear Information System (INIS)

    Zhang, Zhenrong; Bondarchuk, Olexsandr; Kay, Bruce D.; White, J. M.; Dohnalek, Zdenek

    2007-01-01

    Atomically resolved scanning tunneling microscopy (STM) images of identical regions of a TiO2(110) surface were gathered before and after controlled doses of 2-butanol (CH3CH2CH(OH)CH3) at ambient temperature (∼300 K). When dosing is initiated, 2-butanol preferentially adsorbs at bridge-bonded oxygen vacancy (BBOv) sites and dissociates via O-H, not C-O, bond scission to form paired 2-butoxy and hydroxyl species evidenced by two local maxima in STM line profiles. The measured separation is 0.4 nm, slightly larger than the measured separation (0.3 nm) between neighboring bridge-bonded oxygen anions in the surface unit cell of TiO2(110). As the dose increases, but before all the BBOv are occupied, there is direct STM evidence of hydroxyl proton hopping to an adjacent oxygen anion row. This process is facilitated by species bound to 5-coordinate Ti4+ rows, presumably undissociated 2-butanol, that hop slowly compared the STM imaging time scale. The backbones of these mobile species are centered over the Ti4+ rows with preference for lying parallel to these rows. On the other hand, the carbon backbones of the 2-butoxy species that fill BBOv's are centered over the O2- rows and prefer an orientation perpendicular to these rows. As the oxygen vacancy concentration increases from 0.4 to 11% and 2-butanol is dosed the ratio of mobile species to 2-butoxy species decreases for doses that do not fill all the BBOv

  5. Photocatalytic degradation of paracetamol on TiO2 nanoparticles and TiO2/cellulosic fiber under UV and sunlight irradiation

    Directory of Open Access Journals (Sweden)

    Nabil Jallouli

    2017-05-01

    Full Text Available In the present study, photocatalytic degradation of acetaminophen ((N-(4-hydroxyphe-nylacetamide, an analgesic drug has been investigated in a batch reactor using TiO2 P25 as a photocatalyst in slurry and under UV light. Using TiO2 P25 nanoparticles, much faster photodegradation of paracetamol and effective mineralization occurred, more than 90% of 2.65 × 10−4 M paracetamol was degraded under UV irradiation. Changes in pH values affected the adsorption and the photodegradation of paracetamol. pH 9.0 is found to be the optimum for the photodegradation of paracetamol. HPLC detected hydroquinone, benzoquinone, p-nitrophenol, and 1,2,4-trihydroxybenzene during the TiO2-assisted photodegradation of paracetamol among which some pathway products are disclosed for the first time. The results showed that TiO2 suspension/UV system is more efficient than the TiO2/cellulosic fiber mode combined to solar light for the photocatalytic degradation of paracetamol. Nerveless the immobilization of TiO2 showed many advantages over slurry system because it can enhance adsorption properties while allowing easy separation of the photocatalyst from the treated solution with improved reusable performance.

  6. 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.

  7. Synthesis of TiO2-doped SiO2 composite films and its applications

    Indian Academy of Sciences (India)

    Wintec

    structure of the titanium oxide species in the TiO2-doped SiO2 composite films and the photocatalytic reactiv- ity in order to ... gaku D-max γA diffractometer with graphite mono- chromized ... FT–IR absorption spectra of TiO2-doped SiO2 com-.

  8. TiO2-Based Advanced Oxidation Nanotechnologies For Water Purification And Reuse

    Science.gov (United States)

    TiO2 photocatalysis, one of the UV-based advanced oxidation technologies (AOTs) and nanotechnologies (AONs), has attracted great attention for the development of efficient water treatment and purification systems due to the effectiveness of TiO2 to generate ...

  9. Oxidation and photo-oxidation of water on TiO2 surface

    DEFF Research Database (Denmark)

    Valdes, A.; Qu, Z.W.; Kroes, G.J.

    2008-01-01

    The oxidation and photo-oxidation of water on the rutile TiO2(110) surface is investigated using density functional theory (DFT) calculations. We investigate the relative stability of different surface terminations of TiO2 interacting with H2O and analyze the overpotential needed for the electrol...

  10. Hazards of TiO2 and amorphous SiO2 nanoparticles

    NARCIS (Netherlands)

    Reijnders, L.; Kahn, H.A.; Arif, I.A.

    2012-01-01

    TiO2 and amorphous SiO2 nanoparticles have been described as ‘safe’, ‘non-toxic’ and ‘environment friendly’ in scientific literature. However, though toxicity data are far from complete, there is evidence that these nanoparticles are hazardous. TiO2 nanoparticles have been found hazardous to humans

  11. Spectral Sensitization of TiO2 Substrates by Monolayers of Porphyrin Heterodimers

    NARCIS (Netherlands)

    Koehorst, R.B.M.; Boschloo, G.K.; Savenije, T.J.; Goossens, A.; Schaafsma, T.J.

    2000-01-01

    Photoelectrochemical cells have been constructed by depositing monolayers of oriented covalently linked zinc/free base porphyrin heterodimers onto ~30 nm nonporous layers of TiO2 on ITO, deposited by metal-organic chemical vapor deposition (MO-CVD), and onto ~100 nm porous, nanostructured TiO2

  12. Construction of hydrophobic wood surfaces by room temperature deposition of rutile (TiO2) nanostructures

    Science.gov (United States)

    Rongbo Zheng; Mandla A. Tshabalala; Qingyu Li; Hongyan Wang

    2015-01-01

    A convenient room temperature approach was developed for growing rutile TiO2 hierarchical structures on the wood surface by direct hydrolysis and crystallization of TiCl3 in saturated NaCl aqueous solution.The morphology and the crystal structure of TiO2 coated on the wood surface were characterized...

  13. TiO2 Based Photocatalyst: From Synthesis and Characterization to Optimization and Design

    DEFF Research Database (Denmark)

    Su, Ren

    2012-01-01

    TiO2 based photocatalyst has attracted gerat attentions from both fundamental and an applied aspects in water/air purifications and energy production. In this thesis, series of well-defined TiO2 photocatalyst with various parameters (i.e., polymorph composition, shape, impurity concentration, sur...

  14. Characterization of low temperature deposited atomic layer deposition TiO2 for MEMS applications

    NARCIS (Netherlands)

    Huang, Y.; Pandraud, G.; Sarro, P.M.

    2012-01-01

    TiO2 is an interesting and promising material for micro-/nanoelectromechanical systems (MEMS/NEMS). For high performance and reliable MEMS/NEMS, optimization of the optical characteristics, mechanical stress, and especially surface smoothness of TiO2 is required. To overcome the roughness issue of

  15. 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.

  16. Hydrothermal synthesis of TiO2 Nanotubes: Microwave heating versus conventional heating

    CSIR Research Space (South Africa)

    Sikhwivhilu, LM

    2010-01-01

    Full Text Available The influence of the method of synthesis in the properties of the tubular structures derived from TiO2 was investigated using XRD, SEM and BET analysis. The use of microwave irradiation resulted in the formation of TiO2 tubes comprising anatase...

  17. TiO2 Photocatalysis Damages Lipids and Proteins in Escherichia coli

    NARCIS (Netherlands)

    Carre, Gaelle; Hamon, Erwann; Ennahar, Said; Estner, Maxime; Lett, Marie-Claire; Horvatovich, Peter; Gies, Jean-Pierre; Keller, Valerie; Keller, Nicolas; Andre, Philippe

    This study investigates the mechanisms of UV-A (315 to 400 nm) photocatalysis with titanium dioxide (TiO2) applied to the degradation of Escherichia coli and their effects on two key cellular components: lipids and proteins. The impact of TiO2 photocatalysis on E. coli survival was monitored by

  18. New TiO2/DSAT Immobilization System for Photodegradation of Anionic and Cationic Dyes

    Directory of Open Access Journals (Sweden)

    Wan Izhan Nawawi Wan Ismail

    2015-01-01

    Full Text Available A new immobilized TiO2 technique was prepared by coating TiO2 solution onto double-sided adhesive tape (DSAT as a thin layer binder without adding any organic additives. Glass plate was used as support material to immobilized TiO2/DSAT. Two different charges of dyes were applied, namely, anionic reactive red 4 (RR4 and cationic methylene blue (MB dyes. Photocatalytic degradation of RR4 and MB dyes was observed under immobilized TiO2/DSAT with the degradation rate slightly lower and higher, respectively, compared with TiO2 in suspension mode. It was observed that DSAT is able to provide a very strong intact between glass and TiO2 layers thus making the reusability of immobilized TiO2/DSAT be up to 30 cycles. In fact, a better photodegradation activity was observed by number of cycles due to increasing formation of pores on TiO2 surface observed by SEM analysis.

  19. Photocatalytic properties of porous TiO2/Ag thin films

    International Nuclear Information System (INIS)

    Chang, C.-C.; Chen, J.-Y.; Hsu, T.-L.; Lin, C.-K.; Chan, C.-C.

    2008-01-01

    In this study, nanocrystalline TiO 2 /Ag composite thin films were prepared by a sol-gel spin-coating technique. By introducing polystyrene (PS) spheres into the precursor solution, porous TiO 2 /Ag thin films were prepared after calcination at a temperature of 500 deg. C for 4 h. Three different sizes (50, 200, and 400 nm) of PS spheres were used to prepare porous TiO 2 films. The as-prepared TiO 2 and TiO 2 /Ag thin films were characterized by X-ray diffractometry (XRD) and by scanning electron microscopy to reveal structural and morphological differences. In addition, the photocatalytic properties of these films were investigated by degrading methylene blue under UV irradiation. When PS spheres of different sizes were introduced after calcination, the as-prepared TiO 2 films exhibited different porous structures. XRD results showed that all TiO 2 /Ag films exhibited a major anatase phase. The photodegradation of porous TiO 2 thin films prepared with 200 nm PS spheres and doped with 1 mol% Ag exhibited the best photocatalytic efficiency where ∼ 100% methylene blue was decomposed within 8 h under UV exposure

  20. Synthesis of nanocrystalline TiO2 thin films by liquid phase ...

    Indian Academy of Sciences (India)

    WINTEC

    goes degradation efficiently in presence of TiO2 thin films by exposing its aqueous solution to .... Figure 6. Photodegradation of IGOR organic dye by a. bare TiO2 thin film and b. ... Meng L-J and Dos Santos M P 1993 Thin Solid Films 226 22.

  1. 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 ...

  2. 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.

  3. Growth and characterization of hydroxyapatite nanorice on TiO2 nanofibers

    KAUST Repository

    Chetibi, Loubna; Hamana, Djamel; Achour, Slimane

    2014-01-01

    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

  4. Electrospinning processed nanofibrous TiO2 membranes for photovoltaic applications

    Science.gov (United States)

    Onozuka, Katsuhiro; Ding, Bin; Tsuge, Yosuke; Naka, Takayuki; Yamazaki, Michiyo; Sugi, Shinichiro; Ohno, Shingo; Yoshikawa, Masato; Shiratori, Seimei

    2006-02-01

    We have recently fabricated dye-sensitized solar cells (DSSCs) comprising nanofibrous TiO2 membranes as electrode materials. A thin TiO2 film was pre-deposited on fluorine doped tin oxide (FTO) coated conducting glass substrate by immersion in TiF4 aqueous solution to reduce the electron back-transfer from FTO to the electrolyte. The composite polyvinyl acetate (PVac)/titania nanofibrous membranes can be deposited on the pre-deposited thin TiO2 film coated FTO by electrospinning of a mixture of PVac and titanium isopropoxide in N,N-dimethylformamide (DMF). The nanofibrous TiO2 membranes were obtained by calcining the electrospun composite nanofibres of PVac/titania as the precursor. Spectral sensitization of the nanofibrous TiO2 membranes was carried out with a ruthenium (II) complex, cis-dithiocyanate-N,N'-bis(2,2'-bipyridyl-4,4'-dicarboxylic acid) ruthenium (II) dihydrate. The results indicated that the photocurrent and conversion efficiency of electrodes can be increased with the addition of the pre-deposited TiO2 film and the adhesion treatment using DMF. Additionally, the dye loading, photocurrent, and efficiency of the electrodes were gradually increased by increasing the average thickness of the nanofibrous TiO2 membranes. The efficiency of the fibrous TiO2 photoelectrode with the average membrane thickness of 3.9 µm has a maximum value of 4.14%.

  5. Nanoscale surface potential imaging of the photocatalytic TiO2 films on aluminum

    DEFF Research Database (Denmark)

    Daviðsdóttir, Svava; Dirscherl, Kai; Canulescu, Stela

    2013-01-01

    in the surface potential of TiO2 coatings upon UV-illumination are closely correlated to the band gap and thickness of the coatings. The inhomogeneity surface potential distribution of a 100 nm TiO2 film indicates a heterogeneous coating. Transition to a homogeneous surface potential distribution was observed...

  6. Hot corrosion performance of LVOF sprayed Al2O3–40% TiO2 ...

    Indian Academy of Sciences (India)

    ficients of thermal expansions of the two. ... size 40 mesh just prior to deposition of the coating. Al2O3–. 40% TiO2 ... the laboratory Kanthal wire tube furnace, which was cali- ... formation of TiO2, Al2O3 and Al2Ti7O15 phases in the coat- ing.

  7. Intrinsic Photocatalytic Assessment of Reactively Sputtered TiO2 Films

    NARCIS (Netherlands)

    Rafieian Boroujeni, Damon; Driessen, Rick Theodorus; Driessen, Rick T.; Ogieglo, Wojciech; Lammertink, Rob G.H.

    2015-01-01

    Thin TiO2 films were prepared by DC magnetron reactive sputtering at different oxygen partial pressures. Depending on the oxygen partial pressure during sputtering, a transition from metallic Ti to TiO2 was identified by spectroscopic ellipsometry. The crystalline nature of the film developed during

  8. 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.

  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. 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

  11. 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.

  12. Azo dyes decomposition on new nitrogen-modified anatase TiO2 with high adsorptivity

    International Nuclear Information System (INIS)

    Janus, M.; Choina, J.; Morawski, A.W.

    2009-01-01

    New vis active photocatalyst was obtained by the modification of commercial anatase TiO 2 (Police, Poland) in pressure reactor in an ammonia water atmosphere at 100 o C for 4 h. The photocatalytic activity of new material was tested during three azo dyes decomposition: monoazo (Reactive Read), diazo (Reactive Black) and poliazodye (Direct Green). Obtained photocatalyst had new bands at 1430-1440 cm -1 attributed to the bending vibrations of NH 4 + and at 1535 cm -1 associated with NH 2 groups or NO 2 and NO. UV-vis/DR spectra of photocatalyst had also insignificant decrease in visible region. Fluorescence technique was used for studying the amount of hydroxyl radicals produced on TiO 2 surface during visible light irradiation. The hydroxyl radicals produced react with coumarin present in the solution to form 7-hydroxycoumarin which has fluorescent capacity. Photocatalytic activity of modified TiO 2 was compared with commercial titanium dioxide P25 (Degussa, Germany). The photocatalytic activity of TiO 2 /N was higher than that of unmodified material and P25 under visible light irradiation. The ability for dye adsorption (Reactive Red) on photocatalyst surface was also tested. Unmodified TiO 2 and P25 has isotherm of adsorption by Freundlich model, and nitrogen-modified TiO 2 by Langmuir model. The presence of nitrogen at the surface of TiO 2 significantly increased adsorption capacity of TiO 2 as well as OH· radicals formation under visible radiation.

  13. Y-doping TiO2 nanorod arrays for efficient perovskite solar cells

    Science.gov (United States)

    Deng, Xinlian; Wang, Yanqing; Cui, Zhendong; Li, Long; Shi, Chengwu

    2018-05-01

    To improve the electron transportation in TiO2 nanorod arrays and charge separation in the interface of TiO2/perovskite, Y-doping TiO2 nanorod arrays with the length of 200 nm, diameter of 11 nm and areal density of 1050 μm-2 were successfully prepared by the hydrothermal method and the influence of Y/Ti molar ratios of 0%, 3%, 5% in the hydrothermal grown solutions on the growth of TiO2 nanorod arrays was investigated. The results revealed that the appropriate Y/Ti molar ratios can increase the areal density of the corresponding TiO2 nanorod arrays and improve the charge separation in the interface of the TiO2/perovskite. The Y-doping TiO2 nanorod array perovskite solar cells with the Y/Ti molar ratio of 3% exhibited a photoelectric conversion efficiency (PCE) of 18.11% along with an open-circuit voltage (Voc) of 1.06 V, short-circuit photocurrent density (Jsc) of 22.50 mA cm-2 and fill factor (FF) of 76.16%, while the un-doping TiO2 nanorod array perovskite solar cells gave a PCE of 16.42% along with Voc of 1.04 V, Jsc of 21.66 mA cm-2 and FF of 72.97%.

  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. First-Principles Modeling of Polaron Formation in TiO2 Polymorphs.

    Science.gov (United States)

    Elmaslmane, A R; Watkins, M B; McKenna, K P

    2018-06-21

    We present a computationally efficient and predictive methodology for modeling the formation and properties of electron and hole polarons in solids. Through a nonempirical and self-consistent optimization of the fraction of Hartree-Fock exchange (α) in a hybrid functional, we ensure the generalized Koopmans' condition is satisfied and self-interaction error is minimized. The approach is applied to model polaron formation in known stable and metastable phases of TiO 2 including anatase, rutile, brookite, TiO 2 (H), TiO 2 (R), and TiO 2 (B). Electron polarons are predicted to form in rutile, TiO 2 (H), and TiO 2 (R) (with trapping energies ranging from -0.02 eV to -0.35 eV). In rutile the electron localizes on a single Ti ion, whereas in TiO 2 (H) and TiO 2 (R) the electron is distributed across two neighboring Ti sites. Hole polarons are predicted to form in anatase, brookite, TiO 2 (H), TiO 2 (R), and TiO 2 (B) (with trapping energies ranging from -0.16 eV to -0.52 eV). In anatase, brookite, and TiO 2 (B) holes localize on a single O ion, whereas in TiO 2 (H) and TiO 2 (R) holes can also be distributed across two O sites. We find that the optimized α has a degree of transferability across the phases, with α = 0.115 describing all phases well. We also note the approach yields accurate band gaps, with anatase, rutile, and brookite within six percent of experimental values. We conclude our study with a comparison of the alignment of polaron charge transition levels across the different phases. Since the approach we describe is only two to three times more expensive than a standard density functional theory calculation, it is ideally suited to model charge trapping at complex defects (such as surfaces and interfaces) in a range of materials relevant for technological applications but previously inaccessible to predictive modeling.

  16. Positively charged TiO2 particles in non-polar system for electrophoretic display

    International Nuclear Information System (INIS)

    Chang, Young Seon

    2005-02-01

    Electrophoretic display uses a technique called electrophoresis to represent images and letters electronically with electronic ink. Although it has good characteristics such as wide viewing angle, high contrast ratio and extremely low power consumption, there are still several issues to be resolved to improve its performances. Higher mobility and stability of the ink particles are the most important issues among them. In this study, TiO 2 particles coated with acrylamide were found to be effective ink particles that satisfy higher mobility and stability. The TiO 2 particles coated with 5∼40% acrylamide were prepared by dispersion polymerization using monomers of methyl methacrylate (MMA) and acrylamide. The TiO 2 particles coated with acrylamide were dispersed in isopar-G with sorbitan esters such as span 20, span 80 and span 85. The size of the TiO 2 particles were changed from 200±150 nm to 350∼500 nm by the coating process. The morphology of coated particles was observed using a transmission electron microscope (TEM) and thermogravimetric analysis (TGA). From the TGA results, the weight fraction of TiO 2 and polymer in coated particle were calculated. From the zeta potential measurement, it was shown that as acrylamide concentration was increased from 5% to 30%, zeta potential of the coated TiO 2 particles was increased from 50mV to about 230mV. The zeta potential of the coated TiO 2 particles with 40% acrylamide was decreased to 50mV. As a stabilizer, span 85 was the most effective surfactant to improve stability of the TiO 2 particles coated with acrylamide among used surfactants in this study. Span 85 showed best stability in the storage test with TiO 2 particles coated with 10% acrylamide. The mobility of TiO 2 particles coated with acrylamide with span 85 in dye solution (Oil Blue-N dissolved in isopar-G) were measured by ITO cell test. The mobility of TiO 2 particles coated with 10∼30% acrylamide was over 600μm 2 /Vs while the mobility of TiO 2 particles coated with 40% acrylamide was about 400μm 2 /Vs. Span 85 was effective to improve the mobility of TiO 2 particles coated with acrylamide. As the concentration of span 85 was increased from 0 to 1.75 vol %, mobility of the TiO 2 particles coated with 20% acrylamide was increased from 250μm 2 /Vs to about 720μ 2 /Vs

  17. Structural, optical and ferromagnetic properties of Cr doped TiO2 nanoparticles

    International Nuclear Information System (INIS)

    Choudhury, Biswajit; Choudhury, Amarjyoti

    2013-01-01

    Graphical abstract: Doping of Cr 3+ distorts the lattice of TiO 2 , generate oxygen vacancies and create d-band states in the mid band gap of TiO 2 . Incorporation of Cr 3+ also imparts magnetism in non-magnetic TiO 2 by undergoing coupling with the neighboring oxygen vacancies. -- Highlights: • Incorporation of Cr 3+ increases the concentration of oxygen vacancies in TiO 2 nanoparticles. • Doped TiO 2 nanoparticles contain absorption peaks corresponding to d–d transition of Cr 3+ into TiO 2 . • Pure and doped TiO 2 nanoparticles contain emission peaks related to oxygen vacancies. • Pure TiO 2 shows diamagnetism while Cr doped TiO 2 shows ferromagnetism. • The ferromagnetism is due to the interaction of Cr 3+ ions via oxygen vacancies. -- Abstract: Cr doped TiO 2 nanoparticles are prepared with three different concentrations of chromium, 1.5%, 3.0% and 4.5 mol% respectively. Doping decreases the crystallinity and increases the width of the X-ray diffraction peak. The Raman active E g peak of TiO 2 nanoparticles become asymmetric and shifted to higher energy on doping of 4.5% chromium. Electron paramagnetic resonance spectra reveal the presence of Cr 3+ in the host TiO 2 matrix. The absorption spectra of Cr doped TiO 2 nanoparticles contain absorption peaks corresponding to d–d transition of Cr 3+ in octahedral coordination. Most of the visible emission peaks are due to the electrons trapped in the oxygen vacancy centers. Undoped TiO 2 nanoparticles show diamagnetism at room temperature while all chromium doped samples show ferromagnetism. The magnetization of the doped samples increases at 1.5% and 3.0% and decreases at 4.5%. The ferromagnetism arises owing to the interaction of the neighboring Cr 3+ ions via oxygen vacancies. The decrease of magnetization at the highest doping is possibly due to the antiferromagnetic interactions of Cr 3+ pairs or due to Cr 3+ -O 2− -Cr 3+ superexchange interaction in the lattice

  18. N-doped hollow urchin-like anatase TiO2@C composite as a novel anode for Li-ion batteries

    Science.gov (United States)

    Xing, Yalan; Wang, Shengbin; Fang, Baizeng; Song, Ge; Wilkinson, David P.; Zhang, Shichao

    2018-05-01

    N-doped hollow urchin-like anatase TiO2 spheres (HUTSs) with carbon coating (HUTS@C) are prepared through a facile and scalable hydrothermal reaction followed by coating of polypyrrole and carbonization. The HUTS is composed of radially grown anatase nanorods and possesses an enhanced percentage of exposed {001} facets compared with P25 TiO2 nanoparticles. After the carbon coating, the HUTS@C retains the hollow nanostructure although covered with an N-doped carbon layer. As an anode for Li-ion batteries, the HUTS@C delivers a higher capacity of 165.1 mAh g-1 at 1C after 200 cycles and better rate capability (111.7 mAh g-1 at 10C) than the HUTS. Further electrochemical studies reveal that the HUTS@C has a better electrochemical reversibility, lower charge-transfer resistance, and higher Li-ion diffusion coefficient due to its unique nanosctructure including the hollow core, anatase phase of TiO2 microspheres with high exposed {001} facets and the N-doped carbon layer, which facilitates mass transport and enhances electrical conductivity.

  19. Synergistic effects for the TiO2/RuO2/Pt photodissociation of water

    Energy Technology Data Exchange (ETDEWEB)

    Blondel, G; Harriman, A; Williams, D

    1983-07-01

    Compressed discs of naked TiO2 or TiO2 coated with a thin film of a noble metal (e.g. Pt) do not photodissociate water upon illumination with UV light, but small amounts of H2 are generated if the TiO2 has been reduced in a stream of H2 at 600 C. Discs prepared from mixtures of TiO2/RuO2 facilitate the UV photodissociation of water into H2 and O2 although the yields are very low. When a thin (about 9 nm) film of Pt is applied to the TiO2/RuO2 discs, the yields of H2 and O2 observed upon irradiation with UV light are improved drastically. 25 references.

  20. Properties of phases in HfO2-TiO2 system

    International Nuclear Information System (INIS)

    Red'ko, V.P.; Terekhovskij, P.B.; Majster, I.M.; Shevchenko, A.V.; Lopato, L.M.; Dvernyakova, A.A.

    1990-01-01

    A study was made on axial and linear coefficients of thermal expansion (CTE) of HfO 2 -TiO 2 system samples in concentration range of 25-50 mol% TiO 2 . Samples, containing 35 and 37 mol% TiO 2 , are characterized by the lowest values of linear CTE. Dispersion of the basic substances doesn't affect CTE value. Correlation with axial and linear CTE of samples in ZrO 2 -TiO 2 system was conducted. Presence of anisotropy of change of lattice parameters was supported for samples, containing 37.5 and 40 mol% TiO 2 . Polymorphous transformations for hafnium titanate were not revealed

  1. Enhanced photoelectrochemical properties of TiO2 nanorod arrays decorated with CdS nanoparticles

    International Nuclear Information System (INIS)

    Xie, Zheng; Wang, Weipeng; Liu, Can; Li, Zhengcao; Liu, Xiangxuan; Zhang, Zhengjun

    2014-01-01

    TiO 2 nanorod arrays (TiO 2 NRAs) sensitized with CdS nanoparticles were fabricated via successive ion layer adsorption and reaction (SILAR), and TiO 2 NRAs were obtained by oxidizing Ti NRAs obtained through oblique angle deposition. The TiO 2 NRAs decorated with CdS nanoparticles exhibited excellent photoelectrochemical and photocatalytic properties under visible light, and the one decorated with 20 SILAR cycles CdS nanoparticles shows the best performance. This can be attributed to the enhanced separation of electrons and holes by forming heterojunctions of CdS nanoparticles and TiO 2 NRAs. This provides a promising way to fabricate the material for solar energy conversion and wastewater degradation. (paper)

  2. Effects of highly ordered TiO2 nanotube substrates on the nucleation of Cu electrodeposits.

    Science.gov (United States)

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

    2010-05-01

    We investigated the effects of TiO2 nanotube substrates on the nucleation density of Cu during electrodeposition in a solution of CuSO4 and H2SO4 at 50 degrees C compared with those of pure Ti and micro-porous TiO2 substrates. During electrodeposition, the density of Cu nuclei on the TiO2 nanotube substrate increased and the average size of Cu nuclei decreased with increasing anodizing voltage and time for the synthesis of the substrate. In addition, the nucleation density of Cu electrodeposits on the highly ordered TiO2 nanotube substrate was much higher than that on pure Ti and micro-porous TiO2 substrates.

  3. Preparation of anatase TiO2 thin films by vacuum arc plasma evaporation

    International Nuclear Information System (INIS)

    Miyata, Toshihiro; Tsukada, Satoshi; Minami, Tadatsugu

    2006-01-01

    Anatase titanium dioxide (TiO 2 ) thin films with high photocatalytic activity have been prepared with deposition rates as high as 16 nm/min by a newly developed vacuum arc plasma evaporation (VAPE) method using sintered TiO 2 pellets as the source material. Highly transparent TiO 2 thin films prepared at substrate temperatures from room temperature to 400 deg. C exhibited photocatalytic activity, regardless whether oxygen (O 2 ) gas was introduced during the VAPE deposition. The highest photocatalytic activity and photo-induced hydrophilicity were obtained in anatase TiO 2 thin films prepared at 300 deg. C, which correlated to the best crystallinity of the films, as evidenced from X-ray diffraction. In addition, a transparent and conductive anatase TiO 2 thin film with a resistivity of 2.6 x 10 -1 Ω cm was prepared at a substrate temperature of 400 deg. C without the introduction of O 2 gas

  4. Three-dimensional observation of TiO2 nanostructures by electron tomography

    KAUST Repository

    Suh, Young Joon

    2013-03-01

    Three-dimensional nanostructures of TiO2 related materials including nanotubes, electron acceptor materials in hybrid polymer solar cells, and working electrodes of dye sensitized solar cells (DSSCs) were visualized by electron tomography as well as TEM micrographs. The regions on the wall of TiO2 nanotubes where the streptavidins were attached were elucidated by electron tomogram analysis. The coverage of TiO2 nanotubes by streptavidin was also investigated. The TiO2 nanostructures in hybrid polymer solar cells made by sol-gel and atomic layer deposition (ALD) methods and the morphologies of pores between TiO2 particles in DSSCs were also observed by reconstructed three-dimensional images made by electron tomography. © 2012 Elsevier Ltd.

  5. Antimicrobial and Barrier Properties of Bovine Gelatin Films Reinforced by Nano TiO2

    Directory of Open Access Journals (Sweden)

    R. Nassiri

    2013-11-01

    Full Text Available The effects of nano titanium dioxide incorporation were investigated on the water vaporpermeability, oxygen permeability, and antimicrobial properties of bovine gelatin films. The nano TiO2 (TiO2-N was homogenized by sonication and incorporated into bovine gelatin solutions at different concentrations(e.g. 1, 2, 3, and 5% w/w of dried gelatin. The permeability of the films to water vapor and oxygen wassignificantly decreased by incorporating of low concentration TiO2-N to gelatin solutions. TiO2-N gelatin filmsshowed an excellent antimicrobial activity against Staphylococcus aureus and Escherichia coli. Theseproperties suggest that TiO2-N has the potential as filler in gelatin-based films for using as an active packagingmaterials in pharmaceutical and food packaging industries.

  6. Optimized monolayer grafting of 3-aminopropyltriethoxysilane onto amorphous, anatase and rutile TiO 2

    Science.gov (United States)

    Song, Yan-Yan; Hildebrand, Helga; Schmuki, Patrik

    2010-02-01

    Experimental conditions were studied for optimized attachment of 3-aminopropyltriethoxysilane (APTES) onto amorphous, anatase and rutile titanium dioxide (TiO 2) surfaces. The attachment process and extent was characterized using X-ray photoelectron spectroscopy (XPS). In particular, the effect of attachment time, silane concentration, reaction temperature and the TiO 2 crystalline structure on the growth kinetics of the silane layers was studied. The measurements reveal that typically monolayers are more dense on amorphous than on crystalline TiO 2. The results show that critical experimental conditions exist where APTES attachment to the TiO 2 surface changes from a monolayer to a multilayer growth mode. The obtained results and parameters to produce optimized APTES layers are of a high practical relevance as APTES attachment often constitutes the initial step for organic modification of TiO 2 surface with biorelevant molecules such as proteins, enzymes or growth factors.

  7. One-Dimensional TiO2 Nanostructures as Photoanodes for Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Jie Qu

    2013-01-01

    Full Text Available Titanium dioxide (TiO2 is star materials due to its remarkable optical and electronic properties, resulting in various applications, especially in the fields of dye-sensitized solar cells (DSSCs. Photoanode is the most important part of the DSSCs, which help to adsorb dye molecules and transport the injected electrons. The size, structure, and morphology of TiO2 photoanode have been found to show significant influence on the photovoltaic performance of DSSCs. In this paper, we briefly summarize the synthesis and properties of one-dimensional (1D TiO2 nanomaterials (bare 1D TiO2 nanomaterial and 1D hierarchical TiO2 and their photovoltaic performance in DSSCs.

  8. Excess electrons in reduced rutile and anatase TiO2

    Science.gov (United States)

    Yin, Wen-Jin; Wen, Bo; Zhou, Chuanyao; Selloni, Annabella; Liu, Li-Min

    2018-05-01

    As a prototypical photocatalyst, TiO2 is a material of scientific and technological interest. In photocatalysis and other applications, TiO2 is often reduced, behaving as an n-type semiconductor with unique physico-chemical properties. In this review, we summarize recent advances in the understanding of the fundamental properties and applications of excess electrons in reduced, undoped TiO2. We discuss the characteristics of excess electrons in the bulk and at the surface of rutile and anatase TiO2 focusing on their localization, spatial distribution, energy levels, and dynamical properties. We examine specific features of the electronic states for photoexcited TiO2, for intrinsic oxygen vacancy and Ti interstitial defects, and for surface hydroxyls. We discuss similarities and differences in the behaviors of excess electrons in the rutile and anatase phases. Finally, we consider the effect of excess electrons on the reactivity, focusing on the interaction between excess electrons and adsorbates.

  9. Recent Advances in Graphene Based TiO2 Nanocomposites (GTiO2Ns for Photocatalytic Degradation of Synthetic Dyes

    Directory of Open Access Journals (Sweden)

    Rita Giovannetti

    2017-10-01

    Full Text Available Synthetic dyes are widely used in textile, paper, food, cosmetic, and pharmaceutical industries. During industrial processes, some of these dyes are released into the wastewater and their successive release into rivers and lakes produces serious environmental problems. TiO2 is one of the most widely studied and used photocatalysts for environmental remediation. However, it is mainly active under UV-light irradiation due to its band gap of 3.2 eV, while it shows low efficiency under the visible light spectrum. Regarding the exploration of TiO2 activation in the visible light region of the total solar spectrum, the incorporation of carbon nanomaterials, such as graphene, in order to form carbon-TiO2 composites is a promising area. Graphene, in fact, has a large surface area which makes it a good adsorbent for organic pollutants removal through the combination of electrostatic attraction and π-π interaction. Furthermore, it has a high electron mobility and therefore it reduces the electron-hole pair recombination, improving the photocatalytic activity of the semiconductor. In recent years, there was an increasing interest in the preparation of graphene-based TiO2 photocatalysts. The present short review describes the recent advances in TiO2 photocatalyst coupling with graphene materials with the aim of extending the light absorption of TiO2 from UV wavelengths into the visible region, focusing on recent progress in the design and applications in the photocatalytic degradation of synthetic dyes.

  10. ADSORCIÓN DE ALDEHÍDOS INSATURADOS SOBRE TiO2

    Directory of Open Access Journals (Sweden)

    Natalia Ortega

    2012-01-01

    Full Text Available En el presente trabajo se estudió la adsorción de aldehídos insaturados sobre la superficie del TiO2. Para evaluar su eficiencia como catalizador, se realizaron experimentos de fotocatálisis heterogénea de p-nitrofenol (PNF y una muestra proveniente de efluentes industriales. Se empleó un simulador solar y cuatro sistemas de TiO2: el TiO2-sólo (sin modificar y los sistemas TiO2-dienal constituidos por la adsorción química de 2,4 hexadienal, 2,4 heptadienal y el trans-cinamaldehído sobre la superficie del TiO2. La adsorción de los aldehídos insaturados sobre el TiO2 se cuantificó empleando los modelos de adsorción de Langmuir y Freundlich. Se evaluó la influencia del pH en los sistemas TiO2-dienal y su efecto en la degradación fotocatalítica del PNF. En condiciones básicas, la constante de velocidad del PNF es mayor al emplear los sistemas TiO2-dienal en comparación con el TiO2-sólo, mientras que en condiciones ácidas se encontró la tendencia opuesta. El sistema TiO2-cina resultó ser el fotocatalizador de mayor eficiencia.

  11. Synthesis and photocatalytic activity of graphene based doped TiO2 nanocomposites

    International Nuclear Information System (INIS)

    Gu, Yongji; Xing, Mingyang; Zhang, Jinlong

    2014-01-01

    Graphical abstract: - Highlights: • Graphene based doped TiO 2 nanocomposites were prepared. • The intimate contact between doped TiO 2 and graphene is achieved simultaneously. • These nanocomposites showed higher photocatalytic activity than TiO 2 and doped TiO 2 . • Photocatalytic mechanism was explained thoroughly. - Abstract: The nanocomposites of reduced graphene oxide based nitrogen doped TiO 2 (N–TiO 2 –RGO) and reduced graphene oxide based nitrogen and vanadium co-doped TiO 2 (N, V–TiO 2 –RGO) were prepared via a facile hydrothermal reaction of graphene oxide and TiO 2 in a water solvent. In this hydrothermal treatment, the reduction of graphene oxide and the intimate contact between nitrogen doped TiO 2 (N–TiO 2 ) or nitrogen and vanadium co-doped TiO 2 (N,V–TiO 2 ) and the RGO sheet is achieved simultaneously. Both N–TiO 2 –RGO and N,V–TiO 2 –RGO nanocomposites exhibit much higher visible light photocatalytic activity than N–TiO 2 and N,V–TiO 2 , and the order of visible light photocatalytic activity is N,V–TiO 2 –RGO > N–TiO 2 –RGO > N,V–TiO 2 > N–TiO 2 > TiO 2 . According to the characterization, the enhanced photocatalytic activity of the nanocomposites is attributed to reasons, such as enhancement of adsorption of pollutants, light absorption intensity, minimizing the recombination of photoinduced electrons and holes and more excited states of these nanocomposites under visible light irradiation. Overall, this work provides a more marked contrast of graphene based semiconductor nanocomposites and a more comprehensive explanation of the mechanism

  12. 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

  13. 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.

  14. Significant enhancement in the photocatalytic activity of N, W co-doped TiO2 nanomaterials for promising environmental applications

    International Nuclear Information System (INIS)

    Thind, Sapanbir S; Wu Guosheng; Tian Min; Chen Aicheng

    2012-01-01

    In this work, a mesoporous N, W co-doped TiO 2 photocatalyst was synthesized via a one-step solution combustion method, which utilized urea as the nitrogen source and sodium tungstate as the tungsten source. The photocatalytic activity of the N, W co-doped TiO 2 photocatalyst was significantly enhanced by a facile UV pretreatment approach and was evaluated by measuring the rate of photodegradation of Rhodamine B under both UV and visible (λ > 420) light. Following the UV pretreatment, the UV photocatalytic activity of the N, W co-doped TiO 2 was doubled. In terms of visible light activity, the UV pretreatment resulted in an extraordinary >12 fold improvement. In order to gain insight into this substantial enhancement, the N, W co-doped TiO 2 photocatalysts were studied using x-ray diffraction, transmission electron microscopy, N 2 physisorption, UV–vis absorbance spectroscopy and x-ray photoelectron spectroscopy prior to and following the UV pretreatment. Our experimental results have revealed that this significant augmentation of photocatalytic activity may be attributed to several synergetic factors, including increase of the specific surface area, reduction of the band gap energy and the removal of carbon impurities. (paper)

  15. Core/Shell Structure of TiO2-Coated MWCNTs for Thermal Protection for High-Temperature Processing of Metal Matrix Composites

    Directory of Open Access Journals (Sweden)

    Laura Angélica Ardila Rodriguez

    2018-01-01

    Full Text Available The production of metal matrix composites with elevated mechanical properties depends largely on the reinforcing phase properties. Due to the poor oxidation resistance of multiwalled carbon nanotubes (MWCNTs as well as their high reactivity with molten metal, the processing conditions for the production of MWCNT-reinforced metal matrix composites may be an obstacle to their successful use as reinforcement. Coating MWCNTs with a ceramic material that acts as a thermal protection would be an alternative to improve oxidation stability. In this work, MWCNTs previously functionalized were coated with titanium dioxide (TiO2 layers of different thicknesses, producing a core-shell structure. Heat treatments at three different temperatures (500°C, 750°C, and 1000°C were performed on coated nanotubes in order to form a stable metal oxide structure. The MWCNT/TiO2 hybrids produced were evaluated in terms of thermal stability. Thermogravimetric analysis (TGA, X-ray diffraction (XRD, scanning electron microscopy (SEM, Fourier transform infrared spectroscopy (FTIR, Raman spectroscopy (RS, and X-ray photoelectron spectroscopy (XPS were performed in order to investigate TiO2-coated MWCNT structure and thermal stability under oxidative atmosphere. It was found that the thermal stability of the TiO2-coated MWCNTs was dependent of the TiO2 layer morphology that in turn depends on the heat treatment temperature.

  16. Synergistic Effects of Sm and C Co-Doped Mixed Phase Crystalline TiO2 for Visible Light Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Fuchang Peng

    2017-02-01

    Full Text Available Mixed phase TiO2 nanoparticles with element doping by Sm and C were prepared via a facile sol-gel procedure. The UV-Vis light-diffuse reflectance spectroscopy analysis showed that the absorption region of co-doped TiO2 was shifted to the visible-light region, which was attributed to incorporation of samarium and carbon into the TiO2 lattice during high-temperature reaction. Samarium effectively decreased the anatase-rutile phase transformation. The grain size can be controlled by Sm doping to achieve a large specific surface area useful for the enhancement of photocatalytic activity. The photocatalytic activities under visible light irradiation were evaluated by photocatalytic degradation of methylene blue (MB. The degradation rate of MB over the Sm-C co-doped TiO2 sample was the best. Additionally, first-order apparent rate constants increased by about 4.3 times compared to that of commercial Degusssa P25 under the same experimental conditions. Using different types of scavengers, the results indicated that the electrons, holes, and •OH radicals are the main active species for the MB degradation. The high visible-light photocatalytic activity was attributed to low recombination of the photo-generated electrons and holes which originated from the synergistic effect of the co-doped ions and the heterostructure.

  17. 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.

  18. Structural and optical properties of AgCl-sensitized TiO2 (TiO2 @AgCl prepared by a reflux technique under alkaline condition

    Directory of Open Access Journals (Sweden)

    V. A. Mu’izayanti

    Full Text Available Abstract The AgCl-sensitized TiO2 (TiO2@AgCl has been prepared from the precursor of TiO2-rutile type which on its surface adsorb chloride anion (Cl- and various amounts of silver using AgNO3 as starting material: AgNO3/(AgNO3+TiO2 mass ratio of 0.00, 1.14, 3.25, 6.38 and 10.32%. Reflux under alkaline condition was the employed technique. All samples were characterized by X-ray diffraction (XRD and diffuse reflectance UV-vis spectroscopy. The sample without the addition of AgNO3 was analyzed by scanning electron microscope and surface area analyzer. The morphology of the sample showed a distribution of microspheres of approximately 0.5 to 1.0 µm and the specific surface area was 68 m2/g. XRD patterns indicated that the sample without the addition of AgNO3 contained two types of TiO2: rutile (major and anatase (minor, whereas the samples with the addition of AgNO3 consisted of one phase of AgCl and two types of TiO2: rutile and anatase. The bandgaps of the samples were in the range of 2.97 to 3.24 eV, which were very close to the bandgap of intrinsic TiO2 powder. The presence of 0.8, 2.6 and 4.4 wt% of AgCl in each sample resulted in an additional bandgap in visible light region of 1.90, 1.94 and 2.26 eV, respectively, whereas the presence of 9.4 wt% of AgCl in the sample resulted in two bandgaps in visible light region of 1.98 and 1.88 eV.

  19. Interface actions between TiO2 and porous diatomite on the structure and photocatalytic activity of TiO2-diatomite

    International Nuclear Information System (INIS)

    Xia, Yue; Li, Fangfei; Jiang, Yinshan; Xia, Maosheng; Xue, Bing; Li, Yanjuan

    2014-01-01

    TiO 2 -diatomite photocatalysts were prepared by sol–gel process with various pre-modified diatomite. In order to obtain diatomite with different surface characteristics, two modification approaches including calcination and phosphoric acid treatment on the micro-structure of diatomite are introduced. The photocatalysts were characterized by XRD, XPS, nitrogen adsorption–desorption isotherms and micromorphology analysis. The results indicate that, compared with pure TiO 2 , the anatase-to-rutile phase transition temperature of TiO 2 loaded on diatomite carrier is significantly increased to nearly 900 °C, depending on the different pretreatment method of diatomite. The photocatalytic activities of different samples were evaluated by their degradation rate of methyl orange (MO) dye under UV and visible-light irradiation. The samples prepared by phosphoric acid pretreatment method exhibit the highest photocatalytic activity. After 90 min of UV irradiation, about 90% of MO is decomposed by the best effective photocatalyst. And after 8 h visible-light irradiation, nearly 60% of MO is decomposed by the same sample. Further mechanism investigation reveals that the H 3 PO 4 pretreatment process can obviously change the surface features of diatomite carrier, cause the formation of Si–O–Ti bond, increase the binding strength between TiO 2 and diatomite, restrain crystal growth of loaded TiO 2 , and thus form thermal-stable mesoporous structure at the granular spaces. It helps to build micro-, meso- and macro-porous hierarchical porous structure in TiO 2 -diatomite, and improves the charge and mass transfer efficiency during catalyzing process, resulting in the significantly increased photocatalytic activity of TiO 2 -diatomite pretreated by phosphoric acid.

  20. Interface actions between TiO2 and porous diatomite on the structure and photocatalytic activity of TiO2-diatomite

    Science.gov (United States)

    Xia, Yue; Li, Fangfei; Jiang, Yinshan; Xia, Maosheng; Xue, Bing; Li, Yanjuan

    2014-06-01

    TiO2-diatomite photocatalysts were prepared by sol-gel process with various pre-modified diatomite. In order to obtain diatomite with different surface characteristics, two modification approaches including calcination and phosphoric acid treatment on the micro-structure of diatomite are introduced. The photocatalysts were characterized by XRD, XPS, nitrogen adsorption-desorption isotherms and micromorphology analysis. The results indicate that, compared with pure TiO2, the anatase-to-rutile phase transition temperature of TiO2 loaded on diatomite carrier is significantly increased to nearly 900 °C, depending on the different pretreatment method of diatomite. The photocatalytic activities of different samples were evaluated by their degradation rate of methyl orange (MO) dye under UV and visible-light irradiation. The samples prepared by phosphoric acid pretreatment method exhibit the highest photocatalytic activity. After 90 min of UV irradiation, about 90% of MO is decomposed by the best effective photocatalyst. And after 8 h visible-light irradiation, nearly 60% of MO is decomposed by the same sample. Further mechanism investigation reveals that the H3PO4 pretreatment process can obviously change the surface features of diatomite carrier, cause the formation of Si-O-Ti bond, increase the binding strength between TiO2 and diatomite, restrain crystal growth of loaded TiO2, and thus form thermal-stable mesoporous structure at the granular spaces. It helps to build micro-, meso- and macro-porous hierarchical porous structure in TiO2-diatomite, and improves the charge and mass transfer efficiency during catalyzing process, resulting in the significantly increased photocatalytic activity of TiO2-diatomite pretreated by phosphoric acid.

  1. XAS study of TiO2-based nanomaterials

    Science.gov (United States)

    Schneider, K.; Zajac, D.; Sikora, M.; Kapusta, Cz.; Michalow-Mauke, K.; Graule, Th.; Rekas, M.

    2015-07-01

    X-Ray Absorption Spectroscopy studies of the W (0-1 at% W) and Mo-doped TiO2 (0-1 at% Mo) nanoparticle specimens at the K edges of titanium and molybdenum as well as at the L2 L3 edges of tungsten are presented. The materials were prepared with Flame Spray Synthesis process by oxidation of metal-organic precursors. The Ti:K edge spectra in the XANES range show pre-edge and post-edge features characteristic for anatase. A decrease of the amplitude of the EXAFS function with doping is observed and attributed to a softening of the crystal lattice. The Mo EXAFS functions show a considerable decrease of the second-neighbour-shell peak with increasing Mo content, which is attributed to an increased number of cation vacancies. For tungsten a less pronounced effect is observed. The Mo and W XANES spectra do not show noticeable changes with doping level, which indicates their unchanged oxidation states.

  2. Optical spectroscopy of rare earth ion-doped TiO2 nanophosphors.

    Science.gov (United States)

    Chen, Xueyuan; Luo, Wenqin

    2010-03-01

    Trivalent rare-earth (RE3+) ion-doped TiO2 nanophosphors belong to one kind of novel optical materials and have attracted increasing attention. The luminescence properties of different RE3+ ions in various TiO2 nanomaterials have been reviewed. Much attention is paid to our recent progresses on the luminescence properties of RE3+ (RE = Eu, Er, Sm, Nd) ions in anatase TiO2 nanoparticles prepared by a sol-gel-solvothermal method. Using Eu3+ as a sensitive optical probe, three significantly different luminescence centers of Eu3+ in TiO2 nanoparticles were detected by means of site-selective spectroscopy at 10 K. Based on the crystal-field (CF) splitting of Eu3+ at each site, C2v and D2 symmetries were proposed for Eu3+ incorporated at two lattice sites. A structural model for the formation of multiple sites was proposed based on the optical behaviors of Eu3+ at different sites. Similar multi-site luminescence was observed in Sm(3+)- or Nd(3+)-doped TiO2 nanoparticles. In Eu(3+)-doped TiO2 nanoparticles, only weak energy transfer from the TiO2 host to the Eu3+ ions was observed at 10 K due to the mismatch of energy between the TiO2 band-gap and the Eu3+ excited states. On the contrary, efficient host-sensitized luminescences were realized in Sm(3+)- or Nd(3+)-doped anatase TiO2 nanoparticles due to the match of energy between TiO2 band-gap and the Sm3+ and Nd3+ excited states. The excitation spectra of both Sm(3+)- and Nd(3+)-doped samples exhibit a dominant broad peak centered at approximately 340 nm, which is associated with the band-gap of TiO2, indicating that sensitized emission is much more efficient than direct excitation of the Sm3+ and Nd3+ ions. Single lattice site emission of Er3+ in TiO2 nanocrystals can be achieved by modifying the experimental conditions. Upon excitation by a Ti: sapphire laser at 978 nm, intense green upconverted luminescence was observed. The characteristic emission of Er3+ ions was obtained both in the ultraviolet-visible (UV-vis) and near-infrared regions through the high-resolution experiments at 10 K. The CF experienced by Er3+ in TiO2 nanocrystal was systematically studied by means of the energy level fitting.

  3. In situ controlled synthesis of various TiO2 nanostructured materials via a facile hydrothermal route

    International Nuclear Information System (INIS)

    Wang Hai; Liu Yong; Zhong Minyi; Xu Hongmei; Huang Hong; Shen Hui

    2011-01-01

    Various TiO 2 nanomaterials, such as nanosheets, nanoflowers, and nanowires were directly self assembled on titanium substrate on a large scale under hydrothermal conditions. The morphology of the formed TiO 2 nanomaterials could be easily tuned by varying the experimental parameters of temperature, reaction time, and the NaOH concentration. A possible formation mechanism was suggested on the basis of the shape evolution of TiO 2 nanostructures by SEM images in combination with XRD patterns of as-grown samples. The optical properties of TiO 2 nanosheets, nanoflowers, and nanowires were characterized by reflectance spectroscopy. The studies revealed that the absorption capability of visible light is obviously different for TiO 2 with different morphologies. Moreover, TiO 2 nanosheets exhibited better light trapping than TiO 2 nanoflowers and TiO 2 nanowires due to their unique nanostructure.

  4. Alternative photocatalysts to TiO2 for the photocatalytic reduction of CO2

    Science.gov (United States)

    Nikokavoura, Aspasia; Trapalis, Christos

    2017-01-01

    The increased concentration of CO2 in the atmosphere, originating from the burning of fossil fuels in stationary and mobile sources, is referred as the "Anthropogenic Greenhouse Effect" and constitutes a major environmental concern. The scientific community is highly concerned about the resulting enhancement of the mean atmospheric temperature, so a vast diversity of methods has been applied. Thermochemical, electrochemical, photocatalytic, photoelectrochemical processes, as well as combination of solar electricity generation and water splitting processes have been performed in order to lower the CO2 atmospheric levels. Photocatalytic methods are environmental friendly and succeed in reducing the atmospheric CO2 concentration and producing fuels or/and useful organic compounds at the same time. The most common photocatalysts for the CO2 reduction are the inorganic, the carbon based semiconductors and the hybrids based on semiconductors, which combine stability, low cost and appropriate structure in order to accomplish redox reactions. In this review, inorganic semiconductors such as single-metal oxide, mixed-metal oxides, metal oxide composites, layered double hydroxides (LDHs), salt composites, carbon based semiconductors such as graphene based composites, CNT composites, g-C3N4 composites and hybrid organic-inorganic materials (ZIFs) were studied. TiO2 and Ti based photocatalysts are extensively studied and therefore in this review they are not mentioned.

  5. Laser induced photocurrent and photovoltage transient measurements of dye-sensitized solar cells based on TiO_2 nanosheets and TiO_2 nanoparticles

    International Nuclear Information System (INIS)

    Ghaithan, Hamid M.; Qaid, Saif M.H.; Hezam, Mahmoud; Labis, Joselito P.; Alduraibi, Mohammad; Bedja, Idriss M.; Aldwayyan, Abdullah S.

    2016-01-01

    Dye-sensitized solar cells (DSSCs) based on TiO_2 nanoparticles and TiO_2 nanosheets with exposed {001} facets are investigated using laser-induced photovoltage and photocurrent transient decay (LIPVCD) measurements. We adopted a simplified version of LIPVCD technique, in which a single illumination light source and a laboratory oscilloscope could be conveniently used for the measurements. Although the {001} surface of TiO_2 nanosheets allowed a noticeably slower recombination with the electrolyte, this was counterpoised by a slower electron transport probably due to its planar morphology, resulting in a shorter diffusion length in TiO_2 nanosheets. The nanosheet morphology also resulted in less surface area and therefore reduced short circuit current density in the fabricated devices. Our work highlights the fact that the morphological parameters of TiO_2 nanosheets finally resulting after electrode film deposition is of no less importance than the reported efficient dye adsorption and slow electron recombination at the surface of individual nanosheets.

  6. Disruption of Autolysis in Bacillus subtilis using TiO2 Nanoparticles.

    Science.gov (United States)

    McGivney, Eric; Han, Linchen; Avellan, Astrid; VanBriesen, Jeanne; Gregory, Kelvin B

    2017-03-17

    In contrast to many nanotoxicity studies where nanoparticles (NPs) are observed to be toxic or reduce viable cells in a population of bacteria, we observed that increasing concentration of TiO 2 NPs increased the cell survival of Bacillus subtilis in autolysis-inducing buffer by 0.5 to 5 orders of magnitude over an 8 hour exposure. Molecular investigations revealed that TiO 2 NPs prevent or delay cell autolysis, an important survival and growth-regulating process in bacterial populations. Overall, the results suggest two potential mechanisms for the disruption of autolysis by TiO 2 NPs in a concentration dependent manner: (i) directly, through TiO 2 NP deposition on the cell wall, delaying the collapse of the protonmotive-force and preventing the onset of autolysis; and (ii) indirectly, through adsorption of autolysins on TiO 2 NP, limiting the activity of released autolysins and preventing further lytic activity. Enhanced darkfield microscopy coupled to hyperspectral analysis was used to map TiO 2 deposition on B. subtilis cell walls and released enzymes, supporting both mechanisms of autolysis interference. The disruption of autolysis in B. subtilis cultures by TiO 2 NPs suggests the mechanisms and kinetics of cell death may be influenced by nano-scale metal oxide materials, which are abundant in natural systems.

  7. Thiourea-Modified TiO2 Nanorods with Enhanced Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Xiaofeng Wu

    2016-02-01

    Full Text Available Semiconductor TiO2 photocatalysis has attracted much attention due to its potential application in solving the problems of environmental pollution. In this paper, thiourea (CH4N2S modified anatase TiO2 nanorods were fabricated by calcination of the mixture of TiO2 nanorods and thiourea at 600 °C for 2 h. It was found that only N element was doped into the lattice of TiO2 nanorods. With increasing the weight ratio of thiourea to TiO2 (R from 0 to 8, the light-harvesting ability of the photocatalyst steady increases. Both the crystallization and photocatalytic activity of TiO2 nanorods increase first and then decrease with increase in R value, and R2 sample showed the highest crystallization and photocatalytic activity in degradation of Brilliant Red X3B (X3B and Rhodamine B (RhB dyes under visible light irradiation (λ > 420 nm. The increased visible-light photocatalytic activity of the prepared N-doped TiO2 nanorods is due to the synergistic effects of the enhanced crystallization, improved light-harvesting ability and reduced recombination rate of photo-generated electron-hole pairs. Note that the enhanced visible photocatalytic activity of N-doped nanorods is not based on the scarification of their UV photocatalytic activity.

  8. Adsorption and photodegradation of methylene blue on TiO_2-halloysite adsorbents

    International Nuclear Information System (INIS)

    Du, Yuanyuan; Zheng, Pengwu

    2014-01-01

    TiO_2-halloysite (TiO_2-HNT) composites were fabricated by depositing anatase TiO_2 on the halloysite (HNT) surfaces with calcination treatment at 100, 200, 300 and 500 .deg. C. The obtained composites were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and X-Ray diffraction (XRD). HNT was attached with TiO_2 particles or clusters in sizes of 10-30 nm. With the increasing of calcination temperature, the crystalline of anatase became more perfect, but the structure of HNT could be destroyed at 500 .deg. C. The adsorption and photodegradation of methylene blue (MB) by TiO_2-HNTs were investigated. The kinetic adsorption fit the pseudo second-order, and the isotherm data followed the Langmuir model. The maximum adsorption capacities of MB were in the range of 38.57 to 54.29 mg/g. TiO_2-HNTs exhibited an efficient photocatalytic activity in the decomposition of MB. For TiO_2-HNT calcined at 300 .deg. C, 81.6% MB were degraded after 4 h treatment of UV irradiation

  9. High-performance thermoelectric materials based on ternary TiO2/CNT/PANI composites.

    Science.gov (United States)

    Erden, Fuat; Li, Hui; Wang, Xizu; Wang, FuKe; He, Chaobin

    2018-04-04

    In the present work, we report the fabrication of high-performance thermoelectric materials using TiO2/CNT/PANI ternary composites. We showed that a conductivity of ∼2730 S cm-1 can be achieved for the binary CNT (70%)/PANI (30%) composite, which is the highest recorded value for the reported CNT/PANI composites. We further demonstrated that the Seebeck coefficient of CNT/PANI composites could be enhanced by incorporating TiO2 nanoparticles into the binary CNT/PANI composites, which could be attributed to lower carrier density and the energy scattering of low-energy carriers at the interfaces of TiO2/a-CNT and TiO2/PANI. The resulting TiO2/a-CNT/PANI ternary system exhibits a higher Seebeck coefficient and enhanced thermoelectric power. Further optimization of the thermoelectric power was achieved by water treatment and by tuning the processing temperature. A high thermoelectric power factor of 114.5 μW mK-2 was obtained for the ternary composite of 30% TiO2/70% (a-CNT (70%)/PANI (30%)), which is the highest reported value among the reported PANI based ternary composites. The improvement of thermoelectric performance by incorporation of TiO2 suggests a promising approach to enhance power factor of organic thermoelectric materials by judicial tuning of the carrier concentration and electrical conductivity.

  10. Toxicity of nanotitanium dioxide (TiO2-NP) on human monocytes and their mitochondria.

    Science.gov (United States)

    Ghanbary, Fatemeh; Seydi, Enaytollah; Naserzadeh, Parvaneh; Salimi, Ahmad

    2018-03-01

    The effect of nanotitanium dioxide (TiO 2 -NP) in human monocytes is still unknown. Therefore, an understanding of probable cytotoxicity of TiO 2 -NP on human monocytes and underlining the mechanisms involved is of significant interest. The aim of this study was to assess the cytotoxicity of TiO 2 -NP on human monocytes. Using biochemical and flow cytometry assessments, we demonstrated that addition of TiO 2 -NP at 10 μg/ml concentration to monocytes induced cytotoxicity following 12 h. The TiO 2 -NP-induced cytotoxicity on monocytes was associated with intracellular reactive oxygen species (ROS) generation, mitochondrial membrane potential (MMP) collapse, lysosomal membrane injury, lipid peroxidation, and depletion of glutathione. According to our results, TiO 2 -NP triggers oxidative stress and organelles damages in monocytes which are important cells in defense against foreign agents. Finally, our findings suggest that use of antioxidants and mitochondrial/lysosomal protective agents could be of benefit for the people in the exposure with TiO 2 -NP.

  11. Single-Nanoparticle Photoelectrochemistry at a Nanoparticulate TiO2 -Filmed Ultramicroelectrode.

    Science.gov (United States)

    Peng, Yue-Yi; Ma, Hui; Ma, Wei; Long, Yi-Tao; Tian, He

    2018-03-26

    An ultrasensitive photoelectrochemical method for achieving real-time detection of single nanoparticle collision events is presented. Using a micrometer-thick nanoparticulate TiO 2 -filmed Au ultra-microelectrode (TiO 2 @Au UME), a sub-millisecond photocurrent transient was observed for an individual N719-tagged TiO 2 (N719@TiO 2 ) nanoparticle and is due to the instantaneous collision process. Owing to a trap-limited electron diffusion process as the rate-limiting step, a random three-dimensional diffusion model was developed to simulate electron transport dynamics in TiO 2 film. The combination of theoretical simulation and high-resolution photocurrent measurement allow electron-transfer information of a single N719@TiO 2 nanoparticle to be quantified at single-molecule accuracy and the electron diffusivity and the electron-collection efficiency of TiO 2 @Au UME to be estimated. This method provides a test for studies of photoinduced electron transfer at the single-nanoparticle level. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. SAXS Studies of TiO2 Nanoparticles in Polymer Electrolytes and in Nanostructured Films

    Directory of Open Access Journals (Sweden)

    Sigrid Bernstorff

    2010-11-01

    Full Text Available Polymer electrolytes as nanostructured materials are very attractive components for batteries and opto-electronic devices. (PEO8ZnCl2 polymer electrolytes were prepared from PEO and ZnCl2. The nanocomposites (PEO8ZnCl2/TiO2 themselves contained TiO2 nanograins. In this work, the influence of the TiO2 nanograins on the morphology and ionic conductivity of the nanocomposite was systematically studied by transmission small-angle X-ray scattering (SAXS simultaneously recorded with wide-angle X-ray diffraction (WAXD and differential scanning calorimetry (DSC at the synchrotron ELETTRA. Films containing nanosized grains of titanium dioxide (TiO2 are widely used in the research of optical and photovoltaic devices. The TiO2 films, prepared by chemical vapor deposition and e-beam epitaxy, were annealed in hydrogen atmospheres in the temperature range between 20 °C and 900 °C in order to study anatase-rutile phase transition at 740 °C. Also, grazing-incidence small angle X-ray scattering (GISAXS spectra for each TiO2 film were measured in reflection geometry at different grazing incident angles. Environmentally friendly galvanic cells, as well as solar cells of the second generation, are to be constructed with TiO2 film as working electrode, and nanocomposite polymer as electrolyte.

  13. Simplified TiO2 force fields for studies of its interaction with biomolecules

    Science.gov (United States)

    Luan, Binquan; Huynh, Tien; Zhou, Ruhong

    2015-06-01

    Engineered TiO2 nanoparticles have been routinely applied in nanotechnology, as well as in cosmetics and food industries. Despite active experimental studies intended to clarify TiO2's biological effects, including potential toxicity, the relation between experimentally inferred nanotoxicity and industry standards for safely applying nanoparticles remains somewhat ambiguous with justified concerns. Supplemental to experiments, molecular dynamics simulations have proven to be efficacious in investigating the molecular mechanism of a biological process occurring at nanoscale. In this article, to facilitate the nanotoxicity and nanomedicine research related to this important metal oxide, we provide a simplified force field, based on the original Matsui-Akaogi force field but compatible to the Lennard-Jones potentials normally used in modeling biomolecules, for simulating TiO2 nanoparticles interacting with biomolecules. The force field parameters were tested in simulating the bulk structure of TiO2, TiO2 nanoparticle-water interaction, as well as the adsorption of proteins on the TiO2 nanoparticle. We demonstrate that these simulation results are consistent with experimental data/observations. We expect that simulations will help to better understand the interaction between TiO2 and molecules.

  14. Titanium Dioxide (TiO2) Dye-Sensitized Solar Cells

    Science.gov (United States)

    Alseadi, Anwar Abdulaziz

    With the increasing global energy consumption and diminishing fossil fuels, various renewable and sustainable energies have been harvested in past decades and related devices have been fabricated. Dye-sensitized solar cells (DSSCs) are the most efficient third-generation solar cells to harvest solar energy into electricity directly. Titanium dioxide (TiO2) based DSSCs were invented in 1988 and have attracted more and more attention since then because of low-cost and high efficiency. TiO2 nanoparticles are one kind of popular anode materials of DSSC because of stability, abundance, environment safety, non-toxicity, and excellent photovoltaic properties. In the project, TiO2 nanoparticles with different crystallographic sizes were produced by ball-milling. Physical properties of the produced TiO 2 nanoparticles were characterized by X-ray powder diffraction, UV-visible spectroscopy, and Raman scattering. TiO2-based DSSCs were fabricated and their photovoltaic performances were tested. The effects of TiO2 layer thickness, crystallographic size, and microsphere fillings were investigated. The project enriched our understanding of TiO2-based DSSCs.

  15. Enhanced Photocatalytic Properties of Ag-Loaded N-Doped Tio2 Nanotube Arrays

    Directory of Open Access Journals (Sweden)

    Gao Dawei

    2018-03-01

    Full Text Available Highly ordered TiO2 nanotube (TiO2 NT arrays were prepared by anodic oxidizing method on the surface of the Ti substrate. Nitrogen-doped TiO2 nanotube (N-TiO2 NT arrays were carried out by ammonia solution immersion, and Ag nanoparticles loaded N-doped TiO2 nanotube (Ag/N-TiO2 NT arrays were obtained by successive ionic layer adsorption and reaction (SILAR technique. The samples were characterized by the X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, field emission scanning electron microscopy (FESEM, high-resolution transmission electron microscopy (HRTEM, photoluminescence (PL emission spectra, ultraviolet–visible (UV–vis diffuse reflectance spectroscopy (DRS. The result indicated that the diameter and wall thickness of the TiO2 NT are 100–120 and 20–30 nm, respectively. Moreover, the morphology and structure of the highly ordered TiO2 NTs were not affected by N-doping. Furthermore, Ag nanoparticles were evenly deposited on the surface of TiO2 NTs in the form of elemental silver. Finally, the photocatalytic activity of Ag/N-TiO2 NTs was evaluated by degradation of methyl orange (MO under visible-light irradiation. The Ag/N-TiO2 NTs exhibited enhanced photocatalytic properties, which could reach 95% after 90-min irradiation.

  16. 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.

  17. 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.

  18. Enhanced properties of nanostructured TiO2-graphene composites by rapid sintering

    Science.gov (United States)

    Shon, In-Jin; Yoon, Jin-Kook; Hong, Kyung-Tae

    2018-01-01

    Despite of many attractive properties of TiO2, the drawback of TiO2 ceramic is low fracture toughness for widely industrial application. The method to improve the fracture toughness and hardness has been reported by addition of reinforcing phase to fabricate a nanostructured composite. In this regard, graphene has been evaluated as an ideal second phase in ceramics. Nearly full density of nanostructured TiO2-graphene composite was achieved within one min using pulsed current activated sintering. The effect of graphene on microstructure, fracture toughness and hardness of TiO2-graphene composite was evaluated using Vickers hardness tester and field emission scanning electron microscopy. The grain size of TiO2 in the TiO2-x vol% (x = 0, 1, 3, and 5) graphene composite was greatly reduced with increase in addition of graphene. Both hardness and fracture toughness of TiO2-graphene composites simultaneously increased in the addition of graphene.

  19. ALMA observations of TiO2 around VY Canis Majoris

    Science.gov (United States)

    De Beck, E.; Vlemmings, W.; Muller, S.; Black, J. H.; O'Gorman, E.; Richards, A. M. S.; Baudry, A.; Maercker, M.; Decin, L.; Humphreys, E. M.

    2015-08-01

    Context. Titanium dioxide, TiO2, is a refractory species that could play a crucial role in the dust-condensation sequence around oxygen-rich evolved stars. To date, gas phase TiO2 has been detected only in the complex environment of the red supergiant VY CMa. Aims: We aim to constrain the distribution and excitation of TiO2 around VY CMa in order to clarify its role in dust formation. Methods: We analyse spectra and channel maps for TiO2 extracted from ALMA science verification data. Results: We detect 15 transitions of TiO2, and spatially resolve the emission for the first time. The maps demonstrate a highly clumpy, anisotropic outflow in which the TiO2 emission likely traces gas exposed to the stellar radiation field. An accelerating bipolar-like structure is found, oriented roughly east-west, of which the blue component runs into and breaks up around a solid continuum component. A distinct tail to the south-west is seen for some transitions, consistent with features seen in the optical and near-infrared. Conclusions: We find that a significant fraction of TiO2 remains in the gas phase outside the dust-formation zone and suggest that this species might play only a minor role in the dust-condensation process around extreme oxygen-rich evolved stars like VY CMa. Appendix A is available in electronic form at http://www.aanda.org

  20. 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.

  1. 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

  2. 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.

  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. W-doped TiO2 photoanode for high performance perovskite solar cell

    International Nuclear Information System (INIS)

    Liu, Jinwang; Zhang, Jing; Yue, Guoqiang; Lu, Xingwei; Hu, Ziyang; Zhu, Yuejin

    2016-01-01

    Titanium dioxide (TiO 2 ) with dispersed W-doping shows its capability for efficient electron collection from perovskite to TiO 2 in perovskite solar cell. The conduction band (CB) of TiO 2 moves downward (positive shift) with increasing the tungsten (W) content, which enlarges the energy gap between the CB of TiO 2 and the perovskite. Thus, the efficiency of electron injection from perovskite to TiO 2 is increased. Due to the increased electron injection, W-doped TiO 2 (≤0.2% W content) enhances the short-circuit photocurrent (J sc ) of perovskite solar cell and improves the performance of perovskite solar cell. Perovskite solar cell with 0.1% W-doped photoanode obtains the highest power conversion efficiency (η = 10.6%), which shows enhancement by 13% in J sc and by 17% in η, as compared with the undoped TiO 2 perovskite solar cell.

  5. TiO2 nanoparticle biosynthesis and its physiological effect on mung bean (Vigna radiata L.

    Directory of Open Access Journals (Sweden)

    Ramesh Raliya

    2015-03-01

    Full Text Available TiO2 nanoparticle (NPs biosynthesis is a low cost, ecofriendly approach developed using the fungi Aspergillus flavus TFR 7. To determine whether TiO2 NPs is suitable for nutrient, we conducted a two part study; biosynthesis of TiO2 NP and evaluates their influence on mung bean. The characterized TiO2 NPs were foliar sprayed at 10 mgL−1 concentration on the leaves of 14 days old mung bean plants. A significant improvement was observed in shoot length (17.02%, root length (49.6%, root area (43%, root nodule (67.5%, chlorophyll content (46.4% and total soluble leaf protein (94% as a result of TiO2 NPs application. In the rhizosphere microbial population increased by 21.4–48.1% and activity of acid phosphatase (67.3%, alkaline phosphatase (72%, phytase (64% and dehydrogenase (108.7% enzyme was observed over control in six weeks old plants owing to application of TiO2 NPs. A possible mechanism has also been hypothesized for TiO2 NPs biosynthesis.

  6. Photocatalytic and microwave absorbing properties of polypyrrole/Fe-doped TiO2 composite by in situ polymerization method

    International Nuclear Information System (INIS)

    Li Qiaoling; Zhang Cunrui; Li Jianqiang

    2011-01-01

    Research highlights: → Polypyrrole/Fe-doped TiO 2 composite is prepared by in situ polymerization of pyrrole on the Fe-doped TiO 2 template. → The Fe-doped TiO 2 microbelts are prepared by sol-gel method using the absorbent cotton template for the first time. → Then the Fe-doped TiO 2 microbelts are used as template for the preparation of polypyrrole/Fe-doped TiO 2 composites. → The structure, morphology and properties of the composites are characterized with scanning electron microscope (SEM), IR, Net-work Analyzer. → A possible formation mechanism of Fe-doped TiO 2 microbelts and polypyrrole/Fe-doped TiO 2 composites has been proposed. → The effect of the mol ratio of pyrrole/Fe-doped TiO 2 on the photocatalysis properties and microwave loss properties of the composites is investigated. - Abstract: The Fe-doped TiO 2 microbelts were prepared by sol-gel method using the absorbent cotton template for the first time. Then the Fe-doped TiO 2 microbelts were used as templates for the preparation of polypyrrole/Fe-doped TiO 2 composites. Polypyrrole/Fe-doped TiO 2 composites were prepared by in situ polymerization of pyrrole on the Fe-doped TiO 2 template. The structure, morphology and properties of the composites were characterized with scanning electron microscope (SEM), FTIR, Net-work Analyzer. The possible formation mechanisms of Fe-doped TiO 2 microbelts and polypyrrole/Fe-doped TiO 2 composites have been proposed. The effect of the molar ratio of pyrrole/Fe-doped TiO 2 on the photocatalytic properties and microwave loss properties of the composites was investigated.

  7. 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.

  8. 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.

  9. TiO2-BASED Composite Films for the Photodegradation of Oxytetracycline

    Science.gov (United States)

    Li, Hui; Guan, Ling-Xiao; Feng, Ji-Jun; Li, Fang; Yao, Ming-Ming

    2015-02-01

    The spread of the antibiotic oxytetracycline (OTC) has been thought as a threat to the safety of drinking water. In this paper, the photocatalytic activity of the nanocrystalline Fe/Ca co-doped TiO2-SiO2 composite film for the degradation of OTC was studied. The films were characterized by field emission scanning electron microscopy (FE-SEM) equipped with energy-dispersive spectroscopy (EDS), N2 adsorption/desorption isotherms, photoluminescence (PL) spectra, and UV-Vis diffraction reflectance absorption spectra (DRS). The FE-SEM results indicated that the Fe/Ca co-doped TiO2-SiO2 film was composed of smaller nanoparticles compared to pure TiO2 or TiO2-SiO2 film. The BET surface area results showed that the specific surface area of the pure TiO2, TiO2-SiO2 and Ca2+/Fe3+ co-doped TiO2-SiO2 is 118.3 m2g-1, 294.3 m2g-1 and 393.7 m2g-1, respectively. The DRS and PL spectra revealed that the Fe/Ca co-doped TiO2-SiO2 film had strong visible light adsorption and diminished electrons/holes recombination. Experimental results showed that the Fe/Ca co-doped TiO2-SiO2 film is effective in the degradation of OTC under both UV and visible light irradiation.

  10. Preparation, Characterization and Analysis of Fouling Mechanisms of TiO2- Embedded PVDF Membranes

    Directory of Open Access Journals (Sweden)

    Yoones Jafarzadeh

    2017-01-01

    Full Text Available Titanium dioxide (TiO2-embedded polyvinylidene fluoride (PVDF mixed matrix membranes were prepared through a nonsolvent induced phase separation (NIPS method. The structure of the membranes was characterized by FESEM, EDX, water drop contact angle measurement, pure water flux and mean pore radius analysis. The results showed that the prepared membranes had asymmetric structures with macro-voids and the presence of TiO2 nanoparticles increased the size of macro-voids. Moreover, pure water flux increased from 41 kg/m2h to 162 kg/m2h the content of TiO2 nanoparticles increased from 1 wt% to 5 wt% as embedded membrane. The contact angle dropped from 100° for 1 wt% TiO2- embedded membrane to 69° for 5 wt% TiO2-embedded membrane, showing that the hydrophilicity of membranes increased by addition of inorganic TiO2 nanoparticles. The fouling behavior oftheprepared mixed matrix membranes was studied in filtration process of 1% humic acid solution. The results showed that fouling resistance of the membranes increased with higher content of TiO2 nanoparticles. The results of classic fouling modeling of membranes showed that for 2 and 5 wt% TiO2-embedded membranes the best fit of the data occurred with the intermediate blockage model whereas cake formation model was the dominant mechanism for other membranes. Moreover, the analysis of fouling mechanisms by combined models showed that cake filtration-intermediate blockage model was in good agreement with the experimental data for all membranes. Finally, the results showed that the rejection of membranes increased with the addition of TiO2 nanoparticles, and then decreased.

  11. 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.

  12. Preparation and Characterization of Nano-Sized TiO2@Chitosan for Bone Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Lei JIANG

    2016-12-01

    Full Text Available Background: With the development of genetic engineering, it is urgent to find a vector with high transfection efficiency and good biocompatibility for genes. We considered combining nano-TiO2 with chitosan (CTS in order to tap their respective advantages to make a better new nanoparticle as gene vector.Methods: TiO2@CTS was prepared using microemulsion method. The physicochemical property of TiO2@CTS was measured by transmission electron microscopy (TEM and zeta potential. The safety and influence on MC3T3-E1 cells were detected by methyl thiazolyl tetrazolium (MTT, blood compatibility assay and flow cytometry.Results: TiO2@CTS was well prepared and it was safe to cells under concentration tests. TiO2@CTS particles had a fuzzy boundary with a particle size remaining in 20-30 nm. Besides, the results also showed that TiO2@CTS did better in cellular uptake than TiO2 at 2 h and 24 h, and had good biocompatibility. MTT assay proved that the MC3T3 cells remained good growth when treated with different concentrations of TiO2@CTS (2.5, 5, 10, 20, 40 and 80 μg/mL. Moreover, transfection assay in vitro and electrophoretic mobility shift assay illustrated the high transfection efficiency of TiO2@CTS.Conclusion: TiO2@CTS is a good choice to gene transfection, with good biocompatibility, and it also provides a new thought for the application of nanotechnology in the field of aveolar bone graft material.

  13. Photocatalytic degradation and mineralization of microcystin-LR under UV-A, solar and visible light using nanostructured nitrogen doped TiO2

    International Nuclear Information System (INIS)

    Triantis, T.M.; Fotiou, T.; Kaloudis, T.; Kontos, A.G.; Falaras, P.; Dionysiou, D.D.; Pelaez, M.; Hiskia, A.

    2012-01-01

    Highlights: ► N-TiO 2 exhibited effective degradation of MC-LR under UV-A, solar and visible light. ► Complete photocatalytic mineralization of MC-LR was achieved under UV-A and solar light. ► The organic nitrogen is mainly released as ammonium and nitrate ions. - Abstract: In an attempt to face serious environmental hazards, the degradation of microcystin-LR (MC-LR), one of the most common and more toxic water soluble cyanotoxin compounds released by cyanobacteria blooms, was investigated using nitrogen doped TiO 2 (N-TiO 2 ) photocatalyst, under UV-A, solar and visible light. Commercial Degussa P25 TiO 2 , Kronos and reference TiO 2 nanopowders were used for comparison. It was found that under UV-A irradiation, all photocatalysts were effective in toxin elimination. The higher MC-LR degradation (99%) was observed with Degussa P25 TiO 2 followed by N-TiO 2 with 96% toxin destruction after 20 min of illumination. Under solar light illumination, N-TiO 2 nanocatalyst exhibits similar photocatalytic activity with that of commercially available materials such as Degussa P25 and Kronos TiO 2 for the destruction of MC-LR. Upon irradiation with visible light Degussa P25 practically did not show any response, while the N-TiO 2 displayed remarkable photocatalytic efficiency. In addition, it has been shown that photodegradation products did not present any significant protein phosphatase inhibition activity, proving that toxicity is proportional only to the remaining MC-LR in solution. Finally, total organic carbon (TOC) and inorganic ions (NO 2 − , NO 3 − and NH 4 + ) determinations confirmed that complete photocatalytic mineralization of MC-LR was achieved under both UV-A and solar light.

  14. Preparation and Performance of TiO2-ZnO/CNT Hetero-Nanostructures Applied to Photodegradation of Organic Dye

    OpenAIRE

    Da Dalt,Silvana; Alves,Annelise Kopp; Bergmann,Carlos Pérez

    2016-01-01

    Water pollution by organic compounds is one of the major challenges faced by industries that use dyeing processes. Thus, some methods were developed for degrading dyes in wastewaters, including heterogeneous photocatalysis by semiconductor oxides. However, these oxides have limited photocatalytic activity due to the fast recombination of photogenerated electron-hole pairs. The aim of this study is the use of a carbon nanotube (CNT) and TiO2-ZnO oxide junction from modified sol-gel method to p...

  15. An appraisal on the degradation of paracetamol by TiO2/UV system in aqueous medium: product identification by gas chromatography-mass spectrometry (GC-MS)

    OpenAIRE

    Dalmázio,Ilza; Alves,Tânia M. A.; Augusti,Rodinei

    2008-01-01

    The advanced oxidation of paracetamol (1) promoted by TiO2/UV system in aqueous medium was investigated. Continuous monitoring by several techniques, such as UV-Vis spectroscopy, HPLC (high performance liquid chromatography), TOC (total organic carbon), and ESI-MS (electrospray ionization mass spectrometry), revealed that whereas the removal of paracetamol was highly efficient under these conditions, its mineralization was not likewise accomplished. GC-MS (gas chromatography-mass spectrometry...

  16. Interfacial microstructure and mechanical properties of Cf/AZ91D composites with TiO2 and PyC fiber coatings.

    Science.gov (United States)

    Li, Shaolin; Qi, Lehua; Zhang, Ting; Ju, Luyan; Li, Hejun

    2017-10-01

    In spite of the effectiveness of the fiber coatings on interface modification of carbon fiber reinforced magnesium matrix composites, the cost and exclusive equipment for the coatings preparation are usually ignored during research work. In this paper, pyrolytic carbon (PyC) and TiO 2 were coated on carbon fiber surface to study the effects of fiber coatings on interfacial microstructure and mechanical properties of carbon fiber reinforced AZ91D composites (C f /AZ91D composites). It was indicated that both the two coatings could modify the interface and improve the mechanical properties of the composites. The ultimate tensile strength of the TiO 2 -C f /AZ91D and the PyC-C f /AZ91D composite were 333MPa and 400MPa, which were improved by 41.7% and 70.2% respectively, compared with the untreated-C f /AZ91D composite. The microstructure observation revealed that the strengthening of the composites relied on fiber integrity and moderate interfacial bonding. MgO nano-particles were generated at the interface due to the reaction of TiO 2 with Mg in the TiO 2 -C f /AZ91D composite. The volume expansion resulting from the reaction let to disordered intergranular films and crystal defects at the interface. The fibers were protected and the interfacial reaction was restrained by PyC coating in the PyC-C f /AZ91D composite. The principle to select the coating of fiber was proposed by comparing the effectiveness and cost of the coatings. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Liquid phase deposition of WO3/TiO2 heterojunction films with high photoelectrocatalytic activity under visible light irradiation

    International Nuclear Information System (INIS)

    Zhang, Man; Yang, Changzhu; Pu, Wenhong; Tan, Yuanbin; Yang, Kun; Zhang, Jingdong

    2014-01-01

    Highlights: • Liquid phase deposition is developed for preparing WO 3 /TiO 2 heterojunction films. • TiO 2 film provides an excellent platform for WO 3 deposition. • WO 3 expands the absorption band edge of TiO 2 film to visible light region. • WO 3 /TiO 2 heterojunction film shows high photoelectrocatalytic activity. - ABSTRACT: The heterojunction films of WO 3 /TiO 2 were prepared by liquid phase deposition (LPD) method via two-step processes. The scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopic analysis indicated that flower-like WO 3 film was successfully deposited on TiO 2 film with the LPD processes. The TiO 2 film provided an excellent platform for WO 3 deposition while WO 3 obviously expanded the absorption of TiO 2 film to visible light. As the result, the heterojunction film of WO 3 /TiO 2 exhibited higher photocurrent response to visible light illumination than pure TiO 2 or WO 3 film. The photoelectrocatalytic (PEC) activity of WO 3 /TiO 2 film was evaluated by degrading Rhodamin B (RhB) and 4-chlorophenol (4-CP) under visible light irradiation. The results showed that the LPD WO 3 /TiO 2 film possessed high PEC activity for efficient removal of various refractory organic pollutants

  18. 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...

  19. Development and Application of TiO2 Nanoparticles Coupled with Silver Halide

    Directory of Open Access Journals (Sweden)

    Xiaojia Wan

    2014-01-01

    Full Text Available Titanium dioxide (TiO2 is proposed to be effective photocatalyst for wastewater treatment, air purification, and self-cleaning ability, because of its strong oxidation and superhydrophilicity. In order to conquer the limits of TiO2, a variety of methods have been used. This paper presents a critical review of novel research and achievements in the modification of TiO2 nanoparticles with silver halide (AgX, X=Cl, Br, I, which aims at enhancing the visible light absorption and photosensitivity. Herein we study the synthesis, physical and chemical properties, and the mechanism of this composite photocatalyst.

  20. TiO2-Anatase Nanowire Dispersed Composite Electrode for Dye-Sensitized Solar Cells

    International Nuclear Information System (INIS)

    Asagoe, K; Suzuki, Y; Ngamsinlapasathian, S; Yoshikawa, S

    2007-01-01

    TiO 2 anatase nanowires have been prepared by a hydrothermal process followed by post-heat treatment in air. TiO 2 nanoparticle/TiO 2 nanowire composite electrodes were prepared for dye-sensitized solar cells (DSC) in order to improve light-to-electricity conversion efficiency. The TiO 2 NP/TiO 2 NW composite cells showed higher DSC performance than ordinary nanoparticle cells and fully nanowire cells: efficiency (η = 6.53 % for DSC with 10% nanowire, whereas 5.59% for 0% nanowire, and 2.42% for 100% nanowire

  1. Fabrication and electrical characteristics for MIS diode by utilizing TiO2 ceramics

    International Nuclear Information System (INIS)

    Bae, S.H.

    1981-01-01

    Metal insulator semiconductor diodes were made by utilizing TiO 2 ceramics. Tunnel field emission is here proposed as a model for rectification in TiO 2 diode. Measurements of junction depth show very satisfactory agreement with value obtained from the Richardson plot, thus serving as additional supporting evidence of field emission in TiO 2 ceramic. The measured junction area exceeds by a factor of 10 6 the value expected by assuming field emission. The Richardson plot shows a deviation from the emission theory at low voltage, which is probably due to leakage currents which are present in MIS rutile diode. (author)

  2. 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.

  3. 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

  4. Photocatalytic Degradation of Methylene Blue Using TiO2 Impregnated Diatomite

    OpenAIRE

    Zuo, Ranfang; Du, Gaoxiang; Zhang, Weiwei; Liu, Lianhua; Liu, Yanming; Mei, Lefu; Li, Zhaohui

    2014-01-01

    Nano-TiO2 showed a good catalytic activity, but it is easy to agglomerate, resulting in the reduction or even complete loss of photocatalytic activity. The dispersion of TiO2 particles on porous materials was a potential solution to this problem. Diatomite has high specific surface and absorbability because of its particular shell structure. Thus, TiO2/diatomite composite, prepared by loading TiO2 on the surface of diatomite, was a good photocatalyst, through absorbing organic compounds with ...

  5. N-Doped TiO2-Coated Ceramic Membrane for Carbamazepine Degradation in Different Water Qualities

    Science.gov (United States)

    Luster, Enbal; Avisar, Dror; Horovitz, Inna; Lozzi, Luca; Baker, Mark A.; Grilli, Rossana; Mamane, Hadas

    2017-01-01

    The photocatalytic degradation of the model pollutant carbamazepine (CBZ) was investigated under simulated solar irradiation with an N-doped TiO2-coated Al2O3 photocatalytic membrane, using different water types. The photocatalytic membrane combines photocatalysis and membrane filtration in a single step. The impact of each individual constituent such as acidity, alkalinity, dissolved organic matter (DOM), divalent cations (Mg2+ and Ca2+), and Cl− on the degradation of CBZ was examined. CBZ in water was efficiently degraded by an N-doped TiO2-coated Al2O3 membrane. However, elements added to the water, which simulate the constituents of natural water, had an impact on the CBZ degradation. Water alkalinity inhibited CBZ degradation mostly due to increase in pH while radical scavenging by carbonate was more dominant at higher values (>200 mg/L as CaCO3). A negative effect of Ca2+ addition on photocatalytic degradation was found only in combination with phosphate buffer, probably caused by deposition of CaHPO4 or CaHPO4·2H2O on the catalyst surface. The presence of Cl− and Mg2+ ions had no effect on CBZ degradation. DOM significantly inhibited CBZ degradation for all tested background organic compounds. The photocatalytic activity of N-doped TiO2-coated Al2O3 membranes gradually decreased after continuous use; however, it was successfully regenerated by 0.1% HCl chemical cleaning. Nevertheless, dissolution of metals like Al and Ti should be monitored following acid cleaning. PMID:28758982

  6. FTIR study of formic acid interaction with TiO2 and TiO2 doped with Pd and Cu in photocatalytic processes

    International Nuclear Information System (INIS)

    Arana, J.; Garriga i Cabo, C.; Dona-Rodriguez, J.M.; Gonzalez-Diaz, O.; Herrera-Melian, J.A.; Perez-Pena, J.

    2004-01-01

    In this study the different processes occurring on the TiO 2 and Pd and Cu doped TiO 2 surfaces during the photocatalytic formic acid degradation in the presence or absence of S 2 O 8 2- or H 2 O 2 have been investigated. FTIR studies have shown the relevance of the H-bounded hydroxyl groups. It has been observed that formate molecules interact simultaneously with the dopants and surfacial Ti atoms yielding an intermediate species which plays an important role in the phototacatalytic degradation mechanism. Also, it has been determined that Pd or Cu oxides may act as receptors or transmitters of the TiO 2 photogenerated electrons and thus modify the degradation mechanism. Different redox reactions have been proposed according to the obtained results

  7. Photocatalytic degradation of paracetamol on TiO2 nanoparticles and TiO2/cellulosic fiber under UV and sunlight irradiation

    OpenAIRE

    Jallouli, Nabil; Elghniji, Kais; Trabelsi, Hassen; Ksibi, Mohamed

    2014-01-01

    In the present study, photocatalytic degradation of acetaminophen ((N-(4-hydroxyphe-nyl)acetamide)), an analgesic drug has been investigated in a batch reactor using TiO2 P25 as a photocatalyst in slurry and under UV light. Using TiO2 P25 nanoparticles, much faster photodegradation of paracetamol and effective mineralization occurred, more than 90% of 2.65 × 10−4 M paracetamol was degraded under UV irradiation. Changes in pH values affected the adsorption and the photodegradation of paracetam...

  8. Copper doping enhanced the oxidative stress-mediated cytotoxicity of TiO2 nanoparticles in A549 cells.

    Science.gov (United States)

    Ahmad, J; Siddiqui, M A; Akhtar, M J; Alhadlaq, H A; Alshamsan, A; Khan, S T; Wahab, R; Al-Khedhairy, A A; Al-Salim, A; Musarrat, J; Saquib, Q; Fareed, M; Ahamed, M

    2018-05-01

    Physicochemical properties of titanium dioxide nanoparticles (TiO 2 NPs) can be tuned by doping with metals or nonmetals. Copper (Cu) doping improved the photocatalytic behavior of TiO 2 NPs that can be applied in various fields such as environmental remediation and nanomedicine. However, interaction of Cu-doped TiO 2 NPs with human cells is scarce. This study was designed to explore the role of Cu doping in cytotoxic response of TiO 2 NPs in human lung epithelial (A549) cells. Characterization data demonstrated the presence of both TiO 2 and Cu in Cu-doped TiO 2 NPs with high-quality lattice fringes without any distortion. The size of Cu-doped TiO 2 NPs (24 nm) was lower than pure TiO 2 NPs (30 nm). Biological results showed that both pure and Cu-doped TiO 2 NPs induced cytotoxicity and oxidative stress in a dose-dependent manner. Low mitochondrial membrane potential and higher caspase-3 enzyme (apoptotic markers) activity were also observed in A549 cells exposed to pure and Cu-doped TiO 2 NPs. We further observed that cytotoxicity caused by Cu-doped TiO 2 NPs was higher than pure TiO 2 NPs. Moreover, antioxidant N-acetyl cysteine effectively prevented the reactive oxygen species generation, glutathione depletion, and cell viability reduction caused by Cu-doped TiO 2 NPs. This is the first report showing that Cu-doped TiO 2 NPs induced cytotoxicity and oxidative stress in A549 cells. This study warranted further research to explore the role of Cu doping in toxicity mechanisms of TiO 2 NPs.

  9. 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)

  10. Effect of chemisorbed surface species on the photocatalytic activity of TiO2 nanoparticulate films

    International Nuclear Information System (INIS)

    Cao Yaan; Yang Wensheng; Chen Yongmei; Du Hui; Yue, Polock

    2004-01-01

    TiO 2 sols prepared in acidic and basic medium were deposited into films by a spin coating method. Photodegradation experiments showed that photocatalytic activity of the films prepared from acidic sol was much higher than that from basic sol. It is identified that there are more chemisorbed species of CO 2 on the surface of the TiO 2 films from the basic sol than on the surface of the TiO 2 films from the acidic sol. The chemisorbed species of CO 2 reduce the concentration of active species such as hydroxyl group and bridging oxygen on surface of the TiO 2 film and contribute to the formation of surface electron traps in the band gap which are detrimental to charge separation, thus lowering the photocatalytic activity

  11. The properties of transparent TiO2 films for Schottky photodetector

    Directory of Open Access Journals (Sweden)

    Sung-Ho Park

    2017-08-01

    Full Text Available In this data, the properties of transparent TiO2 film for Schottky photodetector are presented for the research article, entitled as “High-performing transparent photodetectors based on Schottky contacts” (Patel et al., 2017 [1]. The transparent photoelectric device was demonstrated by using various Schottky metals, such as Cu, Mo and Ni. This article mainly shows the optical transmittance of the Ni-transparent Schottky photodetector, analyzed by the energy dispersive spectroscopy and interfacial TEM images for transparency to observe the interface between NiO and TiO2 film. The observation and analyses clearly show that no pinhole formation in the TiO2 film by Ni diffusion. The rapid thermal process is an effective way to form the quality TiO2 film formation without degradation, such as pinholes (Qiu et al., 2015 [2]. This thermal process may apply to form functional metal oxide layers for solar cells and photodetectors.

  12. Biomimetic Approach to Solar Cells Based on TiO2 Nanotubes

    National Research Council Canada - National Science Library

    Allen, Jan L; Lee, Ivan C; Wolfenstine, Jeff

    2008-01-01

    The goal of this research was to explore the use of nanotube titanium dioxide (TiO2) as an electrode material in dye-sensitized solar cells in order to further the development of solar cell technology...

  13. 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

  14. Polymer Photovoltaic Cell Using TiO2/G-PEDOT Nanocomplex Film as Electrode

    Directory of Open Access Journals (Sweden)

    F. X. Xie

    2008-01-01

    Full Text Available Using TiO2/G-PEDOT (PEDOT/PSS doped with glycerol nanocomplex film as a substitute for metal electrode in organic photovoltaic cell is described. Indium tin oxide (ITO worked as cathode and TiO2/G-PEDOT nanocomplex works as anode. The thickness of TiO2 layer in nanocomplex greatly affects the act of this nonmetallic electrode of the device. To enhance its performance, this inverted organic photovoltaic cell uses another TiO2 layer as electron selective layer contacted to ITO coated glass substrates. All films made by solution processing techniques are coated on the transparent substrate (glass with a conducting film ITO. The efficiency of this solar cell is compared with the conventional device using Al as electrode.

  15. Influence of TiO2 Nanoparticles on Growth, Chemical Constituents and Toxicity of Fennel Plant

    International Nuclear Information System (INIS)

    Khater, M.S.; Osman, Y.A.H.

    2015-01-01

    The present work is carried out to evaluate the effect of TiO 2 nanoparticles treatments on fennel (Feoniculum Vulgare Mill) plants. The plants were sprayed with different concentrations of TiO 2 nanoparticles 2, 4 and 6 ppm. In most cases, the tallest plants, the highest number of branches , the highest fruit yield per plant and the highest values of Pigments, Carbohydrates, Sugars nitrogen , phosphorus , potassium were obtained from the treatment of 6 ppm TiO 2 nanoparticles of fennel . Results showed that sprayed fennel plant with concentrations of TiO 2 nanoparticles 0, 2, 4 and 6 ppm is safe and enhanced chlorophyll synthesis and consequently enhanced photosynthesis

  16. ADSORCIÓN DE ALDEHÍDOS INSATURADOS SOBRE TiO2

    OpenAIRE

    Natalia Ortega; Oswaldo Núñez

    2012-01-01

    En el presente trabajo se estudió la adsorción de aldehídos insaturados sobre la superficie del TiO2. Para evaluar su eficiencia como catalizador, se realizaron experimentos de fotocatálisis heterogénea de p-nitrofenol (PNF) y una muestra proveniente de efluentes industriales. Se empleó un simulador solar y cuatro sistemas de TiO2: el TiO2-sólo (sin modificar) y los sistemas TiO2-dienal constituidos por la adsorción química de 2,4 hexadienal, 2,4 heptadienal y el trans-cinamaldehído sobre la ...

  17. Molecular design of TiO2 for gigantic red shift via sublattice substitution.

    Science.gov (United States)

    Shao, Guosheng; Deng, Quanrong; Wan, Lin; Guo, Meilan; Xia, Xiaohong; Gao, Yun

    2010-11-01

    The effects of 3d transition metal doping in TiO2 phases have been simulated in detail. The results of modelling indicate that Mn has the biggest potential among 3d transition metals, for the reduction of energy gap and the introduction of effective intermediate bands to allow multi-band optical absorption. On the basis of theoretical formulation, we have incorporated considerable amount of Mn in nano-crystalline TiO2 materials. Mn doped samples demonstrate significant red shift in the optical absorption edge, with a secondary absorption edge corresponding to theoretically predicted intermediate bands/states. The gigantic red shift achievable in Mn-doped TiO2 is expected to extend the useful TiO2 functionalities well beyond the UV threshold via the optical absorption of both visible and infrared photon irradiance.

  18. Control of Electron Transfer from Lead-Salt Nanocrystals to TiO 2

    KAUST Repository

    Hyun, Byung-Ryool; Bartnik, A. C.; Sun, Liangfeng; Hanrath, Tobias; Wise, F. W.

    2011-01-01

    The roles of solvent reorganization energy and electronic coupling strength on the transfer of photoexcited electrons from PbS nanocrystals to TiO 2 nanoparticles are investigated. We find that the electron transfer depends only weakly

  19. GW quasiparticle bandgaps of anatase TiO2 starting from DFT + U.

    Science.gov (United States)

    Patrick, Christopher E; Giustino, Feliciano

    2012-05-23

    We investigate the quasiparticle band structure of anatase TiO(2), a wide gap semiconductor widely employed in photovoltaics and photocatalysis. We obtain GW quasiparticle energies starting from density-functional theory (DFT) calculations including Hubbard U corrections. Using a simple iterative procedure we determine the value of the Hubbard parameter yielding a vanishing quasiparticle correction to the fundamental bandgap of anatase TiO(2). The bandgap (3.3 eV) calculated using this optimal Hubbard parameter is smaller than the value obtained by applying many-body perturbation theory to standard DFT eigenstates and eigenvalues (3.7 eV). We extend our analysis to the rutile polymorph of TiO(2) and reach similar conclusions. Our work highlights the role of the starting non-interacting Hamiltonian in the calculation of GW quasiparticle energies in TiO(2) and suggests an optimal Hubbard parameter for future calculations.

  20. Recent Progress in TiO2-Mediated Solar Photocatalysis for Industrial Wastewater Treatment

    Directory of Open Access Journals (Sweden)

    Tong Zhang

    2014-01-01

    Full Text Available The current paper reviews the application of TiO2-mediated solar photocatalysis for industrial wastewater treatment, starting with a brief introduction on the background of industrial wastewater and the development of wastewater treatment processes, especially advanced oxidation processes (AOPs. We, then, discuss the application of solar TiO2 photocatalysis in treating different kinds of industrial wastewater, such as paper mill wastewater, textile wastewater, and olive mill wastewater. In the end, we compare solar TiO2 photocatalysis with other AOPs in terms of effectiveness, energy, and chemical consumption. Personal perspectives are also given, which may provide new insights to the future development of TiO2 photocatalysis for industrial wastewater.

  1. 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.

  2. Three-dimensional observation of TiO2 nanostructures by electron tomography

    KAUST Repository

    Suh, Young Joon; Lu, Ning; Park, Seong Yong; Lee, Tae Hun; Lee, Sang Hoon; Cha, Dong Kyu; Lee, Min Gun; Huang, Jie; Kim, Sung Soo; Sohn, Byeong Hyeok; Kim, Geung Ho; Ko, Min Jae; Kim, Jiyoung; Kim, Moon J.

    2013-01-01

    Three-dimensional nanostructures of TiO2 related materials including nanotubes, electron acceptor materials in hybrid polymer solar cells, and working electrodes of dye sensitized solar cells (DSSCs) were visualized by electron tomography as well

  3. Novel bamboo structured TiO2 nanotubes for energy storage/production applications

    Science.gov (United States)

    Samuel, J. J.; Beh, K. P.; Cheong, Y. L.; Yusuf, W. A. A.; Yam, F. K.

    2018-04-01

    Nanostructured TiO2 received much attention owing to its high surface-to-volume ratio, which can be advantageous in energy storage and production applications. However, the increase in energy consumption at present and possibly the foreseeable future has demanded energy storage and production devices of even higher performance. A direct approach would be manipulating the physical aspects of TiO2 nanostructures, particularly, nanotubes. In this work, dual voltage anodization system has been implemented to fabricate bamboo shaped TiO2 nanotubes, which offers even greater surface area. This unique nanostructure would be used in Dye Sensitized Solar Cell (DSSC) fabrication and its performance will be evaluated and compared along other forms of TiO2 nanotubes. The results showed that bamboo shaped nanotubes indeed are superior morphologically, with an increase of efficiency of 107% at 1.130% efficiency when compared to smooth walled nanotubes at 0.546% efficiency.

  4. Investigation on the Photoelectrocatalytic Activity of Well-Aligned TiO2 Nanotube Arrays

    Directory of Open Access Journals (Sweden)

    Xiaomeng Wu

    2012-01-01

    Full Text Available Well-aligned TiO2 nanotube arrays were fabricated by anodizing Ti foil in viscous F− containing organic electrolytes, and the crystal structure and morphology of the TiO2 nanotube array were characterized and analyzed by XRD, SEM, and TEM, respectively. The photocatalytic activity of the TiO2 nanotube arrays was evaluated in the photocatalytic (PC and photoelectrocatalytic (PEC degradation of methylene blue (MB dye in different supporting solutions. The excellent performance of ca. 97% for color removal was reached after 90 min in the PEC process compared to that of PC process which indicates that a certain external potential bias favors the promotion of the electrode reaction rate on TiO2 nanotube array when it is under illumination. In addition, it is found that PEC process conducted in supporting solutions with low pH and containing Cl− is also beneficial to accelerate the degradation rate of MB.

  5. 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.

  6. 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.

  7. Variable range hopping in TiO2 insulating layers for oxide electronic devices

    Directory of Open Access Journals (Sweden)

    Y. L. Zhao

    2012-03-01

    Full Text Available TiO2 thin films are of importance in oxide electronics, e.g., Pt/TiO2/Pt for memristors and Co-TiO2/TiO2/Co-TiO2 for spin tunneling devices. When such structures are deposited at a variety of oxygen pressures, how does TiO2 behave as an insulator? We report the discovery of an anomalous resistivity minimum in a TiO2 film at low pressure (not strongly dependent on deposition temperature. Hall measurements rule out band transport and in most of the pressure range the transport is variable range hopping (VRH though below 20 K it was difficult to differentiate between Mott and Efros-Shklovskii's (ES mechanism. Magnetoresistance (MR of the sample with lowest resistivity was positive at low temperature (for VRH but negative above 10 K indicating quantum interference effects.

  8. 1 composite mixture of TiO2 nanoparticles and nanotubes in dye

    Indian Academy of Sciences (India)

    Administrator

    Abstract. TiO2-based nanotubes (NTs), nanoparticles (NPs) and composite structural film (50% NP + 50% ... of faster electron injection ratio compared with other .... exist in this system. .... the open circuit voltage, Im the maximum current and.

  9. Production of TiO_2 particles by sol-gel ultrasound assisted for photocatalytic applications

    International Nuclear Information System (INIS)

    Martinez Rojas, Vanessa; Solis Veliz, Jose; Gomez Leon, Monica; Matejova, Lenka; Lopez, Alcides; Cruz, Gerardo J.

    2015-01-01

    Synthesis of TiO_2 particles was made by sol-gel technique assisted of ultrasonic radiation from an alcoholic solution of titanium isopropoxide. Then was subjected to a heat treatment in air at 350 °C for 1 h. X-ray diffraction and transmission electron microscopy confirmed that the size of the crystalline domains is between 10 and 37 nm. Infrared spectroscopy study confirms the presence of -OH groups on the surface of TiO_2. Modification of the morphology and surface area, due to the influence of exposure time to the ultrasonic radiation, is evidenced by studies of SEM and BET respectively. Properties of TiO_2 obtained were studied by monitoring the degradation of solutions of methyl orange in the presence of UV-A radiation. It was observed that larger the ultrasonic radiation exposure during the TiO_2 synthesis larger the constant velocity for the photocatalytic reaction for the methyl orange. (author)

  10. High-temperature interaction in the ZrSiO4-TiO2 system

    International Nuclear Information System (INIS)

    Matveeva, F.A.; Melekhova, T.F.; Samsonova, T.I.

    1976-01-01

    The solid phase interaction in the ZrSiO 4 - TiO 2 system in the region of lower concentrations of TiO 2 (between 0-30%) when heating in the range 1400-1600 0 C is investigated. The different mechanism of the interaction of zircon and titanium dioxide with a content of titanium dioxide of 10% and higher is shown. In compounds with a TiO 2 content to 10%, a solid solution of titanium dioxide and zircon arises, with a limiting value of TiO 2 dissolving in zircon of 1% at 1400 0 C and 2% at 1500-1600 0 C. The partial decomposition of zircon giving crystobalite and the solid solution of separated zirconium dioxide with rutile occurs when the content of titanium dioxide is higher than 10%

  11. TiO2 Nanoparticles as a Soft X-ray Molecular Probe

    Energy Technology Data Exchange (ETDEWEB)

    Larabell, Carolyn; Ashcroft, Jared M.; Gu, Weiwei; Zhang, Tierui; Hughes, Steven M.; Hartman, Keith B.; Hofmann, Cristina; Kanaras, Antonios G.; Kilcoyne, David A.; Le Gros, Mark; Yin, Yadong; Alivisatos, A. Paul; Larabell, Carolyn A.

    2007-06-30

    With the emergence of soft x-ray techniques for imaging cells, there is a pressing need to develop protein localization probes that can be unambiguously identified within the region of x-ray spectrum used for imaging. TiO2 nanocrystal colloids, which have a strong absorption cross-section within the "water-window" region of x-rays, areideally suited as soft x-ray microscopy probes. To demonstrate their efficacy, TiO2-streptavidin nanoconjugates were prepared and subsequently labeled microtubules polymerized from biotinylated tubulin. The microtubules were imaged using scanning transmission x-ray microscopy (STXM), and the TiO2 nanoparticle tags were specifically identified using x-ray absorption near edge spectroscopy (XANES). These experiments demonstrate that TiO2 nanoparticles are potential probes for protein localization analyses using soft x-ray microscopy.

  12. Non-equilibrium nitrogen DC-arc plasma treatment of TiO2 nanopowder.

    Science.gov (United States)

    Suzuki, Yoshikazu; Gonzalez-Aguilar, José; Traisnel, Noel; Berger, Marie-Hélène; Repoux, Monique; Fulcheri, Laurent

    2009-01-01

    Non-equilibrium nitrogen DC-arc plasma treatment of a commercial TiO2 anatase nanopowder was examined to obtain nitrogen-doped TiO2. By using a non-thermal discharge at low current (150 mA) and high voltage (1200 V) using pure N2 gas, light yellowish-gray TiO2 powder was successfully obtained within a short period of 5-10 min. XPS and TEM-EELS studies confirmed the existence of doped nitrogen. Due to the relatively mild conditions (plasma power of 180 W), metastable anatase structure and fine crystallite size of TiO2 (ca. 10 nm) were maintained after the plasma treatment. The in-flight powder treatment system used in this study is promising for various type of powder treatment.

  13. One-step preparation and photocatalytic performance of vanadium doped TiO2 coatings

    International Nuclear Information System (INIS)

    Vasilić, R.; Stojadinović, S.; Radić, N.; Stefanov, P.; Dohčević-Mitrović, Z.; Grbić, B.

    2015-01-01

    In this paper, we have investigated one-step preparation of vanadium doped TiO 2 coatings formed by plasma electrolytic oxidation (PEO) of titanium in electrolyte containing 10 g/L Na 3 PO 4 ·12H 2 O + 0.5 g/L NH 4 VO 3 . The morphology, phase structure, and elemental composition of the formed coatings were characterized by atomic force microscopy (AFM), x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS) techniques. Ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS) was employed to evaluate the band gap energy of obtained coatings. Vanadium doped TiO 2 coatings are partly crystallized and mainly composed of anatase phase TiO 2 , with up to about 2 wt% of vanadium present in the surface layer of the oxide. The valence band photoelectron spectra and UV–Vis DRS showed that vanadium doped TiO 2 coatings exhibit notable red shift with respect to the pure TiO 2 coatings. The photocatalytic activity was evaluated by monitoring the degradation of methyl orange under simulated sunlight conditions. Photocatalytic activity of vanadium doped TiO 2 coatings increases with PEO time. Prolonged PEO times result in higher roughness of obtained coatings, thus increasing surface area available for methyl orange degradation. Vanadium doped TiO 2 coatings obtained after 180 s of PEO time exhibit the best photocatalytic activity and about 67% of methyl orange is degraded after 12 h of irradiation under simulated sunlight. - Highlights: • One-step preparation of V-doped TiO 2 coatings in 10 g/L Na 3 PO 4 ·12H 2 O + 0.5 g/L NH 4 VO 3 . • Properties of obtained coatings strongly depend on microdischarge characteristics. • Band gap of V-doped TiO 2 coatings is shifted towards red side of the spectrum. • V-doped TiO 2 coatings have better photocatalytic activity than pure TiO 2 . • After 12 h of simulated sunlight irradiation, 67% of methyl orange was decomposed

  14. Karakteristik Pasta TiO2 Suhu Rendah untuk Aplikasi Dye Sensitized Solar Cell (DSSC

    Directory of Open Access Journals (Sweden)

    Mariya Al Qibtiya

    2016-06-01

    Full Text Available Pada tulisan ini, diuraikan karakteristik pasta TiO2 suhu rendah untuk aplikasi sel surya berbasis dye-sensitized yang dipreparasi dengan penambahan serbuk TiO2 reflektor. Penambahan TiO2 reflektor sebagai light scattering layer pada pasta dilakukan untuk melihat pengaruhnya terhadap karakteristik listrik sel surya yang dihasilkan. Preparasi pasta dilakukan menggunakan bahan komersial yaitu pasta T-Nanooxide D-L (Solaronix dan serbuk pasta WER2-O (Dyesiol sebagai bahan reflector. Bahan tersebut dianalisis struktur kristalnya. Hasil karakterisasi X-Ray Diffraction (XRD menunjukan bahwa bahan TiO2 serbuk yang digunakan adalah nanokristal dengan struktur kristal anatase. Pasta ini dideposisi di atas permukaan plastik dan kaca konduktif (ITO-PET dan FTO dengan metode doctor blade printing. Proses sintering lapisan TiO2 dilakukan pada suhu rendah yaitu 120 ˚C selama 4 jam. Morfologi permukaan lapisan TiO2 dianalisa menggunakan Scanning Electron Microscopy (SEM. Lapisan TiO2 yang terbentuk diaplikasikan pada DSSC sebagai fotoelektroda. Pewarnaan dengan larutan N-719 (Ruthenium Complex, lapisan elektroda kerja platina dan larutan elektrolit iodine. Karakteristik kurva I-V dengan ukuran sel daerah aktif 1 cm2 diukur menggunakan Sun Simulator AM1,5 dengan sumber cahaya Xenon dan intensitas 50 mW/cm2. Hasil pengukuran menunjukkan penambahan serbuk TiO2 reflektor dapat meningkatkan unjuk kerja sel surya fleksibel yang dihasilkan. Efisiensi terbaik DSSC yang dihasilkan adalah 0,166% untuk substrat plastik dan 0,167% untuk substrat kaca.

  15. 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.

  16. 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.

  17. 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

  18. Deep-level transient spectroscopy of TiO2/CuInS2 heterojunctions

    NARCIS (Netherlands)

    Nanu, M.; Boulch, F.; Schoonman, J.; Goossens, A.

    2005-01-01

    Deep-level transient spectroscopy (DLTS) has been used to measure the concentration and energy position of deep electronic states in CuInS2. Flat TiO2?CuInS2 heterojunctions as well as TiO2-CuInS2 nanocomposites have been investigated. Subband-gap electronic states in CuInS2 films are mostly due to

  19. Catalytic Study on TiO2 Photo catalyst Synthesised Via Microemulsion Method on Atrazine

    International Nuclear Information System (INIS)

    Ruslimie, C.A.; Hasmizam Razali; Khairul, W.M.

    2011-01-01

    Titanium dioxide photo catalyst was synthesised by microemulsions method under controlled hydrolysis of titanium butoxide, Ti(O(CH 2 ) 3 )CH 3 . The synthesised TiO 2 photo catalyst was compared with Sigma-commercial TiO 2 by carrying out the investigation on its properties using scanning electron microscopy (SEM), x-ray diffraction (XRD) analysis and thermal gravimetric analysis (TGA). The photo catalytic activities for both photo catalysts were studied for atrazine photodegradation. (author)

  20. Physicochemical Study of Photocatalytic Activity of TiO2 Supported Palygorskite Clay Mineral

    Directory of Open Access Journals (Sweden)

    Lahcen Bouna

    2013-01-01

    Full Text Available This study deals with the influence of physicochemical parameters, namely, the photocatalyst loading, dye concentration, and pH of polluted solutions, on the degradation efficiency of Orange G (OG solutions containing TiO2 nanoparticles supported on palygorskite clay mineral (TiO2-Pal. The TiO2 photocatalyst attached to natural palygorskite fibers was elaborated by colloidal sol-gel route. It exhibits the anatase structure that is the most photoactive crystallographic form. The highest performances of supported photocatalyst on OG degradation were found using an optimum amount of TiO2-Pal around 0.8 g·L−1, which corresponds properly to ca. 0.4 g·L−1 of TiO2. This amount is interestingly lower than the 2.5 g·L−1 generally reported when using pure unsupported TiO2 powder. The photodegradation rate increases by decreasing OG initial concentration, and it was found significantly higher when the OG solution is either acidic (pH<4 or basic (pH≈11. For OG concentrations in the range 5×10-6– 5×10-4 M, the kinetic law of the OG degradation in presence of TiO2-Pal is similar to that reported for unsupported TiO2 nanopowder. It follows a Langmuir-Hinshelwood model with a first-order reaction and an apparent rate constant of about 2.9×10-2 min−1.

  1. TiO2 nanoparticles in seawater: Aggregation and interactions with the green alga Dunaliella tertiolecta.

    Science.gov (United States)

    Morelli, Elisabetta; Gabellieri, Edi; Bonomini, Alessandra; Tognotti, Danika; Grassi, Giacomo; Corsi, Ilaria

    2018-02-01

    Titanium dioxide nanoparticles (TiO 2 NPs) have been widely employed in industrial applications, thus rising concern about their impact in the aquatic environment. In this study we investigated the chemical behaviour of TiO 2 NPs in the culture medium and its effect on the green alga Dunaliella tertiolecta, in terms of growth inhibition, oxidative stress, ROS (Reactive Oxygen Species) accumulation and chlorophyll content. In addition, the influence of exopolymeric substances (EPS) excreted by the microalgae on the stability of NPs has been evaluated. The physicochemical characterization showed a high propensity of TiO 2 NPs to form micrometric-sized aggregates within 30min, large enough to partially settle to the bottom of the test vessel. Indeed, an increasing amount of TiO 2 particles settled out with time, but the presence of EPS seemed to mitigate this behaviour in the first 6h of exposure where the main effects in D. tertiolecta were observed. TiO 2 NPs did not inhibit the 72-h growth rate of D. tertiolecta, nor affected the cellular chlorophyll concentration in the range 0.01-10mgL -1 . The time-course of ROS production showed an initial transient increase of ROS in TiO 2 NP-exposed algae compared to the control, concomitant with an enhancement of catalase activity. Interestingly, intracellular ROS was a small fraction of total ROS, the highest amount being extracellular. The occurrence of cell-mediated chemical transformations of TiO 2 NPs in the external medium, related to the presence of EPS, has been evaluated. Our results showed that carbohydrates were the major component of EPS, whereas proteins of medium molecular weight (20-80kDa) were preferentially bound to TiO 2 NPs, likely influencing their biological fate. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. 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.

  3. Microglial cells (BV-2) internalize titanium dioxide (TiO2) nanoparticles: toxicity and cellular responses.

    Science.gov (United States)

    Rihane, Naima; Nury, Thomas; M'rad, Imen; El Mir, Lassaad; Sakly, Mohsen; Amara, Salem; Lizard, Gérard

    2016-05-01

    Because of their whitening and photocatalytic effects, titanium dioxide nanoparticles (TiO2-NPs) are widely used in daily life. These NPs can be found in paints, plastics, papers, sunscreens, foods, medicines (pills), toothpastes, and cosmetics. However, the biological effect of TiO2-NPs on the human body, especially on the central nervous system, is still unclear. Many studies have demonstrated that the brain is one of the target organs in acute or chronic TiO2-NPs toxicity. The present study aimed to investigate the effect of TiO2-NPs at different concentrations (0.1 to 200 μg/mL) on murine microglial cells (BV-2) to assess their activity on cell growth and viability, as well as their neurotoxicity. Different parameters were measured: cell viability, cell proliferation and DNA content (SubG1 peak), mitochondrial depolarization, overproduction of reactive oxygen species (especially superoxide anions), and ultrastructural changes. Results showed that TiO2-NPs induced some cytotoxic effects with a slight inhibition of cell growth. Thus, at high concentrations, TiO2-NPs were not only able to inhibit cell adhesion but also enhanced cytoplasmic membrane permeability to propidium iodide associated with a loss of mitochondrial transmembrane potential and an overproduction of superoxide anions. No induction of apoptosis based on the presence of a SubG1 peak was detected. The microscopic observations also indicated that small groups of nanosized particles and micron-sized aggregates were engulfed by the BV-2 cells and sequestered as intracytoplasmic aggregates after 24-h exposure to TiO2-NPs. Altogether, our data show that the accumulation TiO2-NPs in microglial BV-2 cells favors mitochondrial dysfunctions and oxidative stress.

  4. Adsorption of small hydrocarbons on rutile TiO2(110)

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Long; Smith, R. Scott; Kay, Bruce D.; Dohnalek, Zdenek

    2016-08-01

    Temperature programmed desorption and molecular beam scattering were used to study the adsorption and desorption of small hydrocarbons (n-alkanes, 1-alkenes and 1-alkynes with 1 - 4 carbon atoms of C1-C4) on rutile TiO2(110). We show that the sticking coefficients for all the hydrocarbons are close to unity (> 0.95) at an adsorption temperature of 60 K. The desorption energies for hydrocarbons of the same chain length increase from n-alkanes to 1-alkenes and to 1-alkynes. This trend is likely a consequence of an additional dative bonding of the alkene and alkyne π system to the coordinatively unsaturated Ti5c sites. Similar to previous studies on the adsorption of n-alkanes on metal and metal oxide surfaces, we find the desorption energies within each group (n-alkanes vs. 1-alkenes vs. 1-alkynes) from Ti5c sites increase linearly with the chain length. The absolute saturation coverages of each hydrocarbon on Ti5c sites were also determined. The saturation coverage of CH4, is found to be ~ 2/3 monolayer (ML). The saturation coverages of C2-C4 hydrocarbons are found nearly independent of the chain length with values of ~1/2 ML for n-alkanes and 1-alkenes and 2/3 ML for 1-alkynes. This result is surprising considering their similar sizes.

  5. 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.

  6. Wet-Chemical Preparation of TiO2-Based Composites with Different Morphologies and Photocatalytic Properties

    Directory of Open Access Journals (Sweden)

    Liqin Xiang

    2017-10-01

    Full Text Available TiO2-based composites have been paid significant attention in the photocatalysis field. The size, crystallinity and nanomorphology of TiO2 materials have an important effect on the photocatalytic efficiency. The synthesis and photocatalytic activity of TiO2-based materials have been widely investigated in past decades. Based on our group’s research works on TiO2 materials, this review introduces several methods for the fabrication of TiO2, rare-earth-doped TiO2 and noble-metal-decorated TiO2 particles with different morphologies. We focused on the preparation and the formation mechanism of TiO2-based materials with unique structures including spheres, hollow spheres, porous spheres, hollow porous spheres and urchin-like spheres. The photocatalytical activity of urchin-like TiO2, noble metal nanoparticle-decorated 3D (three-dimensional urchin-like TiO2 and bimetallic core/shell nanoparticle-decorated urchin-like hierarchical TiO2 are briefly discussed.

  7. Effect of dissolved ozone or ferric ions on photodegradation of thiacloprid in presence of different TiO2 catalysts

    International Nuclear Information System (INIS)

    Cernigoj, Urh; Stangar, Urska Lavrencic; Jirkovsky, Jaromir

    2010-01-01

    Combining TiO 2 photocatalysis with inorganic oxidants (such as O 3 and H 2 O 2 ) or transition metal ions (Fe 3+ , Cu 2+ and Ag + ) often leads to a synergic effect. Electron transfer between TiO 2 and the oxidant is usually involved. Accordingly, the degree of synergy could be influenced by TiO 2 surface area. With this in mind, the disappearance of thiacloprid, a neonicotinoid insecticide, was studied applying various photochemical AOPs and different TiO 2 photocatalysts. In photocatalytic ozonation experiments, synergic effect of three different TiO 2 photocatalysts was quantified. Higher surface area resulted in a more pronounced synergic effect but an increasing amount of TiO 2 did not influence the degree of the synergy. This supports the theory that the synergy is a consequence of adsorption of ozone on the TiO 2 surface. No synergy was observed in photocatalytic degradation of thiacloprid in the presence of dissolved iron(III) species performed under varied experimental conditions (concentration, age of iron(III) solution, different TiO 2 films, usage of TiO 2 slurries). This goes against the literature for different organic compounds (i.e., monuron). It indicates different roles of iron(III) in the photodegradation of different organic molecules. Moreover, TiO 2 surface area did not affect photodegradation efficiency in iron(III)-based experiments which could confirm absence of electron transfer between TiO 2 photocatalyst and iron(III).

  8. The Photocatalytic Activity and Compact Layer Characteristics of TiO2 Films Prepared Using Radio Frequency Magnetron Sputtering

    Directory of Open Access Journals (Sweden)

    H. C. Chang

    2014-01-01

    Full Text Available TiO2 compact layers are used in dye-sensitized solar cells (DSSCs to prevent charge recombination between the electrolyte and the transparent conductive substrate (indium tin oxide, ITO; fluorine-doped tin oxide, FTO. Thin TiO2 compact layers are deposited onto ITO/glass by means of radio frequency (rf magnetron sputtering, using deposition parameters that ensure greater photocatalytic activity and increased DSSC conversion efficiency. The photoinduced decomposition of methylene blue (MB and the photoinduced hydrophilicity of the TiO2 thin films are also investigated. The photocatalytic performance characteristics for the deposition of TiO2 films are improved by using the Grey-Taguchi method. The average transmittance in the visible region exceeds 85% for all samples. The XRD patterns of the TiO2 films, for sol-gel with spin coating of porous TiO2/TiO2 compact/ITO/glass, show a good crystalline structure. In contrast, without the TiO2 compact layer (only porous TiO2, the peak intensity of the anatase (101 plane in the XRD patterns for the TiO2 film has a lower value, which demonstrates inferior crystalline quality. With a TiO2 compact layer to prevent charge recombination, a higher short-circuit current density is obtained. The DSSC with the FTO/glass and Pt counter electrode demonstrates the energy conversion efficiency increased.

  9. Photocatalytic Study of New Immobilized TiO2 Technique Towards Degradation of Reactive Red 4 Dye

    Directory of Open Access Journals (Sweden)

    Ain S. K.

    2016-01-01

    Full Text Available The study on TiO2 for wastewater remediation has gained interest among researchers. However, the application of this photocatalyst is limited due to non-recyclability of conventional TiO2. Thus, immobilization technique has been developed to solve this issue. Hence, a comparison study between two types of immobilized photocatalysts namely titanium dioxide (TiO2 and TiO2 mixed with polyvinyl alcohol (PVA has been conducted in this work to observe the significant effect of PVA polymer in photocatalysis reaction of reactive red 4 (RR4 dye. Double sided adhesive tape (DSAT was used as thin layer binder in this immobilization system. The result shows that the photocatalytic performance of TiO2-PVA/DSAT was higher than that of TiO2/DSAT under both normal UV and visible light irradiations due to the conjugated unsaturated polymer from PVA serve as electron donor for TiO2 thus increase the photocatalysis process. Besides, TiO2-PVA/DSAT was also found to possess much better adhesion strength to the support material compared to TiO2/DSAT. Based on the findings, this TiO2 immobilization system is expected to be beneficial in the industrial wastewater treatment. Thus, further study to improve the photocatalytic activity of this immobilized TiO2 will be in our future work.

  10. Degradation of organic dyes using spray deposited nanocrystalline stratified WO3/TiO2 photoelectrodes under sunlight illumination

    Science.gov (United States)

    Hunge, Y. M.; Yadav, A. A.; Mahadik, M. A.; Bulakhe, R. N.; Shim, J. J.; Mathe, V. L.; Bhosale, C. H.

    2018-02-01

    The need to utilize TiO2 based metal oxide hetero nanostructures for the degradation of environmental pollutants like Rhodamine B and reactive red 152 from the wastewater using stratified WO3/TiO2 catalyst under sunlight illumination. WO3, TiO2 and stratified WO3/TiO2 catalysts were prepared by a spray pyrolysis method. It was found that the stratified WO3/TiO2 heterostructure has high crystallinity, no mixed phase formation occurs, strong optical absorption in the visible region of the solar spectrum, and large surface area. The photocatalytic activity was tested for degradation of Rhodamine B (Rh B) and reactive red 152 in an aqueous medium. TiO2 layer in stratified WO3/TiO2 catalyst helps to extend its absorption spectrum in the solar light region. Rh B and Reactive red 152is eliminated up to 98 and 94% within the 30 and 40 min respectively at optimum experimental condition by stratified WO3/TiO2. Moreover, stratified WO3/TiO2 photoelectrode has good stability and reusability than individual TiO2 and WO3 thin film in the degradation of Rh B and reactive red 152. The photoelectrocatalytic experimental results indicate that stratified WO3/TiO2 photoelectrode is a promising material for dye removal.

  11. TiO2 thin-films on polymer substrates and their photocatalytic activity

    International Nuclear Information System (INIS)

    Yang, Jae-Hun; Han, Yang-Su; Choy, Jin-Ho

    2006-01-01

    We have developed dip-coating process for TiO 2 -thin film on polymer substrates (acrylonitrile-butadiene-styrene polymer: ABS, polystyrene: PS). At first, a monodispersed and transparent TiO 2 nano-sol solution was prepared by the controlled hydrolysis of titanium iso-propoxide in the presence of acetylacetone and nitric acid catalyst at 80 deg. C. Powder X-ray diffraction patterns of the dried particles are indicative of crystalline TiO 2 with anatase-type structure. According to the XRD and transmission electron microscopy (TEM) studies, the mean particle size was estimated to be ca. 5 nm. The transparent thin films on ABS and PS substrates were fabricated by dip-coating process by changing the processing variables, such as the number of dip-coating and TiO 2 concentration in nano-sol solution. Scanning electron microscopic (SEM) analysis for the thin film samples reveals that the acetylacetone-modified TiO 2 nano-sol particles are effective for enhancing the interfacial adherence between films and polymeric substrates compared to the unmodified one. Photocatalytic degradation of methylene blue (MB) on the TiO 2 thin-films has also been systematically investigated

  12. Photoetching of Immobilized TiO2-ENR50-PVC Composite for Improved Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    M. A. Nawi

    2012-01-01

    Full Text Available Commercially acquired TiO2 photocatalyst (99% anatase powder was mixed with epoxidized natural rubber-50 (ENR50/polyvinyl chloride (PVC blend by ultrasonication and immobilized onto glass plates as TiO2-ENR50-PVC composite via a dip-coating method. Photoetching of the immobilized TiO2-ENR50-PVC composite was investigated under the irradiation of a 45 W compact fluorescent lamp and characterized by chemical oxygen demand (COD analysis, scanning electron microscopy-energy dispersive X-ray (SEM-EDX spectrometry, thermogravimetry analysis (TGA, and fourier transform infrared (FTIR spectroscopy. The BET surface area of the photoetched TiO2 composite was observed to be larger than the original TiO2 powder due to the systematic removal of ENR50 while PVC was retained within the composite. It also exhibited better photocatalytic efficiency than the TiO2 powder in a slurry mode and was highly reproducible and reusable. More than 98% of MB removal was consistently achieved for 10 repeated runs of the photo-etched photocatalyst system. About 93% of the 20 mg L−1 MB was mineralized over a period of 480 min. The presence of SO42−, NO3−, and Cl− anions was detected in the mineralized solution where the solution pH was reduced from 7 to 4.

  13. The Effects of Doping Copper and Mesoporous Structure on Photocatalytic Properties of TiO2

    Directory of Open Access Journals (Sweden)

    Yang Wang

    2014-01-01

    Full Text Available This paper describes a system for the synthesis of Cu-doped mesoporous TiO2 nanoparticles by a hydrothermal method at relatively low temperatures. The technique used is to dope the as-prepared mesoporous TiO2 system with copper. In this method, the copper species with the form of Cu1+, which was attributed to the reduction effect of dehydroxylation and evidenced by X-ray photoelectron spectroscopy (XPS and X-ray diffraction (XRD, was well dispersed in the optimal concentration 1 wt.% Cu-doped mesoporous TiO2. In this as-prepared mesoporous TiO2 system, original particles with a size of approximately 20 nm are aggregated together to shapes of approximately 1100 nm, which resulted in the porous aggregate structure. More importantly, the enhancement of the photocatalytic activity was discussed as effects due to the formation of stable Cu(I and the mesoporous structure in the Cu-doped mesoporous TiO2. Among them, Cu-doped mesoporous TiO2 shows the highest degradation rate of methyl orange (MO. In addition, the effects of initial solution pH on degradation of MO had also been investigated. As a result, the optimum values of initial solution pH were found to be 3.

  14. Effect of Graphite Doped TiO_2 Nanoparticles on Smoke Degradation

    International Nuclear Information System (INIS)

    Roshasnorlyza Hazan; Mohamad Shahrizal Md Zain; Natrah Syafiqah Rosli

    2016-01-01

    Secondhand smoke affects in the same way as regular smoker. The best solution is to purify the air efficiently and effectively. In this study, we were successfully doped TiO_2 nanoparticle with graphite to accelerate the degradation of cigarette smoke. The graphite doped and undoped TiO_2 nanoparticles were prepared from synthetic rutile using alkaline fusion method and their photo catalytic activity were investigated under visible light irradiation. The photo catalytic activity of the TiO_2 nanoparticles was analyzed in terms of their particle size analysis, crystallization and optical band gap. TiO_2 nanoparticle act as photo catalyzer by utilization of light energy to excite electron-hole pairs in smoke degradation processes. With the aided from graphite in TiO_2 nanoparticles, the smoke degradation was accelerate up to 44.4 %. In this case, graphite helps to reduce optical band gap of TiO_2 nanoparticle, thus increasing excitation of electron from valence band to conduction band. (author)

  15. Enhanced oxidation of naphthalene using plasma activation of TiO2/diatomite catalyst.

    Science.gov (United States)

    Wu, Zuliang; Zhu, Zhoubin; Hao, Xiaodong; Zhou, Weili; Han, Jingyi; Tang, Xiujuan; Yao, Shuiliang; Zhang, Xuming

    2018-04-05

    Non-thermal plasma technology has great potential in reducing polycyclic aromatic hydrocarbons (PAHs) emission. But in plasma-alone process, various undesired by-products are produced, which causes secondary pollutions. Here, a dielectric barrier discharge (DBD) reactor has been developed for the oxidation of naphthalene over a TiO 2 /diatomite catalyst at low temperature. In comparison to plasma-alone process, the combination of plasma and TiO 2 /diatomite catalyst significantly enhanced naphthalene conversion (up to 40%) and CO x selectivity (up to 92%), and substantially reduced the formation of aerosol (up to 90%) and secondary volatile organic compounds (up to near 100%). The mechanistic study suggested that the presence of the TiO 2 /diatomite catalyst intensified the electron energy in the DBD. Meantime, the energized electrons generated in the discharge activated TiO 2 , while the presence of ozone enhanced the activity of the TiO 2 /diatomite catalyst. This plasma-catalyst interaction led to the synergetic effect resulting from the combination of plasma and TiO 2 /diatomite catalyst, consequently enhanced the oxidation of naphthalene. Importantly, we have demonstrated the effectiveness of plasma to activate the photocatalyst for the deep oxidation of PAH without external heating, which is potentially valuable in the development of cost-effective gas cleaning process for the removal of PAHs in vehicle applications during cold start conditions. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Enhancement of tributyltin degradation under natural light by N-doped TiO2 photocatalyst

    International Nuclear Information System (INIS)

    Bangkedphol, S.; Keenan, H.E.; Davidson, C.M.; Sakultantimetha, A.; Sirisaksoontorn, W.; Songsasen, A.

    2010-01-01

    Photo-degradation of tributyltin (TBT) has been enhanced by TiO 2 nanoparticles doped with nitrogen (N-doped TiO 2 ). The N-doped catalyst was prepared by a sol-gel reaction of titanium (IV) tetraisopropoxide with 25% ammonia solution and calcined at various temperatures from 300 to 600 deg. C. X-ray diffraction results showed that N-doped TiO 2 remained amorphous at 300 deg. C. At 400 deg. C the anatase phase occurred then transformed to the rutile phase at 600 deg. C. The crystallite size calculated from Scherrer's equation was in the range of 16-51 nm which depended on the calcination temperature. N-doped TiO 2 calcined at 400 deg. C which contained 0.054% nitrogen, demonstrated the highest photocatalytic degradation of TBT at 28% in 3 h under natural light when compared with undoped TiO 2 and commercial photocatalyst, P25-TiO 2 which gave 14.8 and 18% conversion, respectively.

  17. 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.

  18. 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.

  19. Photocatalytic Degradation of Methylene Blue Using TiO2 Impregnated Diatomite

    Directory of Open Access Journals (Sweden)

    Ranfang Zuo

    2014-01-01

    Full Text Available Nano-TiO2 showed a good catalytic activity, but it is easy to agglomerate, resulting in the reduction or even complete loss of photocatalytic activity. The dispersion of TiO2 particles on porous materials was a potential solution to this problem. Diatomite has high specific surface and absorbability because of its particular shell structure. Thus, TiO2/diatomite composite, prepared by loading TiO2 on the surface of diatomite, was a good photocatalyst, through absorbing organic compounds with diatomite and degrading them with TiO2. Scanning electron microscopy (SEM, energy dispersive spectrum (EDS, X-ray diffraction (XRD, chemical analysis, and Fourier transform infrared spectrometry (FTIR indicated that TiO2 was impregnated well on the surface of diatomite. Furthermore, TiO2/diatomite was more active than nano-TiO2 for the degradation of methylene blue (MB in solution. MB at concentrations of 15 and 35 ppm can be completely degraded in 20 and 40 min, respectively.

  20. Photocatalytic decolorization of basic dye by TiO2 nanoparticle in photoreactor

    Directory of Open Access Journals (Sweden)

    Jutaporn Chanathaworn1

    2012-04-01

    Full Text Available Photocatalytic decolorization of rhodamine B (RB and malachite green (MG basic dyes in aqueous solution wasevaluated using TiO2 powder as a semiconductor photocatalyst under UV black light irradiation. A 0.5 L batch photoreactorcontaining dyeing solution was installed in a stainless steel chamber with air cooling under irradiation. The TiO2 powder wascharacterized by XRD observation and it was shown that the nanoparticles could be identified as 73 nm anatase crystals. Theeffects of operational parameters such as light intensity (0-114 W/m2, initial dye concentration (10-30 mg/L, and TiO2 powderloading (0.5-1.5 g/L on the decolorization of dye samples were examined. The photocatalytic decolorization rate depended onthe pollutant’s structure, such that the MG dye could be removed faster than the RB dye. Decolorization efficiency (% of thephotocatalytic system increased with increasing TiO2 loading and light intensity; however, it decreased with increasing initialdye concentration. A loading of 1.5 g TiO2/L, initial dye concentration of 20 mg/L, and light intensity of 114 W/m2 were foundto yield the highest removal efficiency of dye solution based on time requirement. The kinetics are of first order and dependon the TiO2 powder loading and dye structure. The research had a perfect application foreground.

  1. Phosphorus doped TiO2 as oxygen sensor with low operating temperature and sensing mechanism

    International Nuclear Information System (INIS)

    Han, Zhizhong; Wang, Jiejie; Liao, Lan; Pan, Haibo; Shen, Shuifa; Chen, Jianzhong

    2013-01-01

    Nano-scale TiO 2 powders doped with phosphorus were prepared by sol–gel method. The characterization of the materials was performed by XRD, BET, FT-IR spectroscopy, Zeta potential measurement and XPS analysis. The results indicate that the phosphorus suppresses the crystal growth and phase transformation and, at the same time, increases the surface area and enhances the sensitivity and selectivity for the P-doped TiO 2 oxygen sensors. In this system, the operating temperature is low, only 116 °C, and the response time is short. The spectra of FT-IR and XPS show that the phosphorus dopant presents as the pentavalent-oxidation state in TiO 2 , further phosphorus can connect with Ti 4+ through the bond of Ti-O-P. The positive shifts of XPS peaks indicate that electron depleted layer of P-doped TiO 2 is narrowed compared with that of pure TiO 2 , and the results of Zeta potential illuminate that the density of surface charge carrier is intensified. The adsorptive active site and Lewis acid characteristics of the surface are reinforced by phosphorus doping, where phosphorus ions act as a new active site. Thus, the sensitivity of P-doped TiO 2 is improved, and the 5 mol% P-doped sample has the optimal oxygen sensing properties.

  2. Improved hydrogen storage properties of MgH2 catalyzed with TiO2

    Science.gov (United States)

    Jangir, Mukesh; Meena, Priyanka; Jain, I. P.

    2018-05-01

    In order to improve the hydrogenation properties of the MgH2, various concentration of rutile Titanium Oxide (TiO2) (X wt%= 5, 10, 15 wt %) is added to MgH2 by ball milling and the catalytic effect of TiO2 on hydriding/dehydriding properties of MgH2 has been investigated. Result shows that the TiO2 significantly reduced onset temperature of desorption. Onset temperature as low as 190 °C were observed for the MgH2-15 wt% TiO2 sample which is 60 °C and 160 °C lower than the as-milled and as-received MgH2. Fromm the Kissinger plot the activation energy of 15 wt% TiO2 added sample is calculated to be -75.48 KJ/mol. These results indicate that the hydrogenation properties of MgH2-TiO2 have been improved compared to the as-milled and as-received MgH2. Furthermore, XRD and XPS were performed to characterize the structural evolution upon milling and dehydrogenation.

  3. Antimicrobial Activity of TiO2 Nanoparticle-Coated Film for Potential Food Packaging Applications

    Directory of Open Access Journals (Sweden)

    Siti Hajar Othman

    2014-01-01

    Full Text Available Recent uses of titanium dioxide (TiO2 have involved various applications which include the food industry. This study aims to develop TiO2 nanoparticle-coated film for potential food packaging applications due to the photocatalytic antimicrobial property of TiO2. The TiO2 nanoparticles with varying concentrations (0–0.11 g/ 100 mL organic solvent were coated on food packaging film, particularly low density polyethylene (LDPE film. The antimicrobial activity of the films was investigated by their capability to inactivate Escherichia coli (E. coli in an actual food packaging application test under various conditions, including types of light (fluorescent and ultraviolet (UV and the length of time the film was exposed to light (one–three days. The antimicrobial activity of the TiO2 nanoparticle-coated films exposed under both types of lighting was found to increase with an increase in the TiO2 nanoparticle concentration and the light exposure time. It was also found that the antimicrobial activity of the films exposed under UV light was higher than that under fluorescent light. The developed film has the potential to be used as a food packaging film that can extend the shelf life, maintain the quality, and assure the safety of food.

  4. Novel preparation and photocatalytic activity of one-dimensional TiO2 hollow structures

    International Nuclear Information System (INIS)

    Yu Huogen; Yu Jiaguo; Cheng Bei; Liu Shengwei

    2007-01-01

    Usually, templated methods include two important steps: the coating of nanocrystals on the surface of the templates and the removal of the templates. In this study, one-dimensional TiO 2 hollow structures, based on the template-directed deposition and then in situ template-sacrificial reaction (or dissolution), were prepared by a one-step template method using vanadium oxide nanobelts as the templates and TiF 4 as the precursor at 60 deg. C. The coating of TiO 2 nanoparticles on the surface of the templates was accompanied with the dissolution of vanadium oxide nanobelts by HF produced during the hydrolysis of TiF 4 in the reaction solution. It was found that the prepared one-dimensional TiO 2 hollow structures with a mesoporous wall were composed of TiO 2 nanoparticles with a diameter of 10-55 nm, resulting in a large specific surface area (77.2 m 2 g -1 ) and high pore volume (0.13 cm 3 g -1 ), and the wall thickness of the TiO 2 hollow structures could be easily controlled by adjusting the precursor concentration of TiF 4 . The photocatalytic activity experiment indicated that the prepared one-dimensional TiO 2 hollow structures, which could be readily separated from a slurry system after photocatalytic reaction, exhibited obvious photocatalytic activity for the photocatalytic degradation of methyl orange aqueous solution

  5. Preparation of Nanoporous TiO2 Electrodes for Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Hsiue-Hsyan Wang

    2011-01-01

    Full Text Available Nano-porous TiO2 thin films have been widely used as the working electrodes in dye-sensitized solar cells (DSSCs. In this work, the phase-pure anatase TiO2 (a-TiO2 and rutile TiO2 (r-TiO2 have been prepared using hydrothermal processes. The investigation of photo-to-electron conversion efficiency of DSSCs fabricated from mixed-TiO2 with a-TiO2 and r-TiO2 ratio of 80 : 20 (A8R2 was performed and compared to that from commercial TiO2 (DP-25. The results showed higher efficiency of DSSC for A8R2 cells with same dependence of cell efficiency on the film thickness for both A8R2 and DP-25 cells. The best efficiency obtained in this work is 5.2% from A8R2 cell with TiO2 film thickness of 12.0 μm. The correlation between the TiO2 films thickness and photoelectron chemical properties of DSSCs fabricated from A8R2 and DP-25 was compared and discussed.

  6. Biocompatibility and Surface Properties of TiO2 Thin Films Deposited by DC Magnetron Sputtering

    Science.gov (United States)

    López-Huerta, Francisco; Cervantes, Blanca; González, Octavio; Hernández-Torres, Julián; García-González, Leandro; Vega, Rosario; Herrera-May, Agustín L.; Soto, Enrique

    2014-01-01

    We present the study of the biocompatibility and surface properties of titanium dioxide (TiO2) thin films deposited by direct current magnetron sputtering. These films are deposited on a quartz substrate at room temperature and annealed with different temperatures (100, 300, 500, 800 and 1100 °C). The biocompatibility of the TiO2 thin films is analyzed using primary cultures of dorsal root ganglion (DRG) of Wistar rats, whose neurons are incubated on the TiO2 thin films and on a control substrate during 18 to 24 h. These neurons are activated by electrical stimuli and its ionic currents and action potential activity recorded. Through X-ray diffraction (XRD), the surface of TiO2 thin films showed a good quality, homogeneity and roughness. The XRD results showed the anatase to rutile phase transition in TiO2 thin films at temperatures between 500 and 1100 °C. This phase had a grain size from 15 to 38 nm, which allowed a suitable structural and crystal phase stability of the TiO2 thin films for low and high temperature. The biocompatibility experiments of these films indicated that they were appropriated for culture of living neurons which displayed normal electrical behavior. PMID:28788667

  7. 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.

  8. 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.

  9. Nanocomposites of TiO2/cyanoethylated cellulose with ultra high dielectric constants

    International Nuclear Information System (INIS)

    Madusanka, Nadeesh; Shivareddy, Sai G; Hiralal, Pritesh; Choi, Youngjin; Amaratunga, Gehan A J; Eddleston, Mark D; Oliver, Rachel A

    2016-01-01

    A novel dielectric nanocomposite containing a high permittivity polymer, cyanoethylated cellulose (CRS) and TiO 2 nanoparticles was successfully prepared with different weight percentages (10%, 20% and 30%) of TiO 2 . The intermolecular interactions and morphology within the polymer nanocomposites were analysed. TiO 2 /CRS nanofilms on SiO 2 /Si wafers were used to form metal–insulator–metal type capacitors. Capacitances and loss factors in the frequency range of 1 kHz–1 MHz were measured. At 1 kHz CRS-TiO 2 nanocomposites exhibited ultra high dielectric constants of 118, 176 and 207 for nanocomposites with 10%, 20% and 30% weight of TiO 2 respectively, significantly higher than reported values of pure CRS (21), TiO 2 (41) and other dielectric polymer-TiO 2 nanocomposite films. Furthermore, all three CRS-TiO 2 nanocomposites show a loss factor <0.3 at 1 kHz and low leakage current densities (10 −6 –10 −7 A cm −2 ). Leakage was studied using conductive atomic force microscopy and it was observed that the leakage is associated with TiO 2 nanoparticles embedded in the CRS polymer matrix. A new class of ultra high dielectric constant hybrids using nanoscale inorganic dielectrics dispersed in a high permittivity polymer suitable for energy management applications is reported. (paper)

  10. Construction of anatase/rutile TiO2 hollow boxes for highly efficient photocatalytic performance

    Science.gov (United States)

    Jia, Changchao; Zhang, Xiao; Yang, Ping

    2018-02-01

    Hollow TiO2 hierarchical boxes with suitable anatase and rutile ratios were designed for photocatalysis. The unique hierarchical structure was fabricated via a Topotactic synthetic method. CaTiO3 cubes were acted as the sacrificial templates to create TiO2 hollow hierarchical boxes with well-defined phase distribution. The phase composition of the hollow TiO2 hierarchical boxes is similar to that of TiO2 P25 nanoparticles (∼80% anatase, and 20% rutile). Compared with nanaoparticles, TiO2 hollow boxes with hierarchical structures exhibited an excellent performance in the photocatalytic degradation of methylene blue organic pollutant. Quantificationally, the degradation rate of the hollow boxes is higher than that of TiO2 P25 nanoparticles by a factor of 2.7. This is ascribed that hollow structure provide an opportunity for using incident light more efficiently. The surface hierarchical and well-organized porous structures are beneficial to supply more active sites and enough transport channels for reactant molecules. The boxes consist of single crystal anatase and rutile combined well with each other, which gives photon-generated carriers transfer efficiently.

  11. Sputtered PdO Decorated TiO2 Sensing Layer for a Hydrogen Gas Sensor

    Directory of Open Access Journals (Sweden)

    Jeong Hoon Lee

    2018-01-01

    Full Text Available We report a sputtered PdO decorated TiO2 sensing layer by radiofrequency (RF sputtering methods and demonstrated gas sensing performance for H2 gas. We prepared sputtered anatase TiO2 sensing films with 200 nm thickness and deposited a Pd layer on top of the TiO2 films with a thickness ranging from 3 nm to 13 nm. Using an in situ TiO2/Pd multilayer annealing process at 550°C for 1 hour, we observed that Pd turns into PdO by Auger electron spectroscopy (AES depth profile and confirmed decorated PdO on TiO2 sensing layer from scanning electron microscope (SEM and atomic-force microscope (AFM. We also observed a positive sensing signal for 3, 4.5, and 6.5 nm PdO decorated TiO2 sensor while we observed negative output signal for a 13.5 nm PdO decorated one. Using a microheater platform, we acquired fast response time as ~11 sec and sensitivity as 6 μV/ppm for 3 nm PdO under 33 mW power.

  12. Photocatalytic properties of nanocrystalline TiO2 thin film with Ag additions

    International Nuclear Information System (INIS)

    Chang, C.-C.; Lin, C.-K.; Chan, C.-C.; Hsu, C.-S.; Chen, C.-Y.

    2006-01-01

    In the present study, nanocrystalline TiO 2 /Ag composite thin films were prepared by a sol-gel spin coating technique. While, by introducing polystyrene (PS) microspheres, porous TiO 2 /Ag films were obtained after calcining at a temperature of 500 o C. The as-prepared TiO 2 and TiO 2 /Ag thin films were characterized by X-ray diffractometry, and scanning electron microscopy to reveal the structural and morphological differences. In addition, the photocatalytic properties of these films were investigated by degrading methylene blue under UV irradiation. After 500 o C calcination, the microstructure of PS-TiO 2 film without Ag addition exhibited a sponge-like microstructure while significant sintering effect was noticed with Ag additions and the films exhibited a porous microstructure. Meanwhile, coalescence of nanocrystalline anatase-phase TiO 2 can be observed with respect to the sharpening of XRD diffraction peaks. The photodegradation of porous TiO 2 doped with 1 mol% Ag exhibited the best photocatalytic efficiency where 72% methylene blue can be decomposed after UV exposure for 12 h

  13. Love Wave Ultraviolet Photodetector Fabricated on a TiO2/ST-Cut Quartz Structure

    Directory of Open Access Journals (Sweden)

    Walter Water

    2014-01-01

    Full Text Available A TiO2 thin film deposited on a 90° rotated 42°45′ ST-cut quartz substrate was applied to fabricate a Love wave ultraviolet photodetector. TiO2 thin films were grown by radio frequency magnetron sputtering. The crystalline structure and surface morphology of TiO2 thin films were examined using X-ray diffraction, scanning electron microscope, and atomic force microscope. The effect of TiO2 thin film thickness on the phase velocity, electromechanical coupling coefficient, temperature coefficient of frequency, and sensitivity of ultraviolet of devices was investigated. TiO2 thin film increases the electromechanical coupling coefficient but decreases the temperature coefficient of frequency for Love wave propagation on the 90° rotated 42°45′ ST-cut quartz. For Love wave ultraviolet photodetector application, the maximum insertion loss shift and phase shift are 2.81 dB and 3.55 degree at the 1.35-μm-thick TiO2 film.

  14. 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)

  15. Exposure to TiO2 nanoparticles increases Staphylococcusaureusinfection of HeLa cells

    Science.gov (United States)

    Xu, Yan; Wei, Ming-Tzo; Walker, Stephen. G.; Wang, Hong Zhan; Gondon, Chris; Brink, Peter; Guterman, Shoshana; Zawacki, Emma; Applebaum, Eliana; Rafailovich, Miriam; Ou-Yang, H. Daniel; Mironava, Tatsiana

    TiO2 is one of the most common nanoparticles in industry from food additives to energy generation. Even though TiO2 is also used as an anti-bacterial agent in combination with UV, we found that, in the absence of UV, exposure of HeLa cells to TiO2 nanoparticles largely increased their risk of bacterial invasion. HeLa cells cultured with low dosage rutile and anatase TiO2 nanoparticles (0.1 mg/ml) for 24 hrs prior to exposure to bacteria had 350% and 250% respectively more bacteria infected per cell. The increase was attributed to increased LDH leakage, and changes in the mechanical response of the cell membrane. On the other hand, macrophages exposed to TiO2 particles ingested 40% fewer bacteria, further increasing the risk of infection. In combination, these two factors raise serious concerns regarding the impact of exposure to TiO2 nanoparticles on the ability of organisms to resist bacterial infection.

  16. TiO2 (NanoParticles Extracted from Sugar-Coated Confectionery

    Directory of Open Access Journals (Sweden)

    Martina Lorenzetti

    2017-01-01

    Full Text Available As the debate about TiO2 food additive safety is still open, the present study focuses on the extraction and characterisation of TiO2 (nanoparticles added as a whitening agent to confectionary products, that is, chewing gum pellets. The aim was to (1 determine the colloidal properties of suspensions mutually containing TiO2 and all other chewing gum ingredients in biologically relevant media (preingestion conditions; (2 characterise the TiO2 (nanoparticles extracted from the chewing gum coating (after ingestion; and (3 verify their potential photocatalysis. The particle size distribution, in agreement with the zeta potential results, indicated that a small but significant portion of the particle population retained mean dimensions close to the nanosize range, even in conditions of moderate stability, and in presence of all other ingredients. The dispersibility was enhanced by proteins (i.e., albumin, which acted as surfactants and reduced particle size. The particle extraction methods involved conventional techniques and no harmful chemicals. The presence of TiO2 particles embedded in the sugar-based coating was confirmed, including 17–30% fraction in the nanorange (<100 nm. The decomposition of organics under UV irradiation proved the photocatalytic activity of the extracted (nanoparticles. Surprisingly, photocatalysis occurred even in presence of an amorphous SiO2 layer surrounding the TiO2 particles.

  17. Production and Characterization of (004) Oriented Single Anatase TiO2 Films

    Science.gov (United States)

    Atay, Ferhunde; Akyuz, Idris; Cergel, Muge Soyleyici; Erdogan, Banu

    2018-02-01

    Highly (004) oriented anatase TiO2 films have been successfully obtained by an inexpensive ultrasonic spray pyrolysis technique at low substrate temperatures and without additional annealing. X-ray diffraction analysis, ultraviolet-visible spectroscopy and field emission scanning electron microscopy were used to analyze the structural, optical and surface properties of the films. By using the less reported TiCl4 solution, the optical band gap values falling into the visible region (between 2.70 eV and 2.92 eV) have been obtained for all films. Spectroscopic ellipsometry technique has been used to determine the dispersive refractive index and extinction coefficient of TiO2 films. Possible electrical conduction mechanisms in TiO2 films have been examined using temperature dependent conductivity measurements in the temperature range of 78-300 K. At room temperature, electrical resistivity values of TiO2 films change between 1.68 × 104 Ω cm and 5.88 × 104 Ω cm. Considering the analyzed parameters with respect to substrate temperature, this work refers to the properties of anatase TiO2 films that are strongly correlated to the growth direction, namely (004). As a result, (004) oriented anatase TiO2 films with appropriate optical band gap values are promising materials for technological applications, especially for photocatalysts.

  18. Multi-Layered TiO2 Films towards Enhancement of Escherichia coli Inactivation

    Directory of Open Access Journals (Sweden)

    Sorachon Yoriya

    2016-09-01

    Full Text Available Crystalline TiO2 has shown its great photocatalytic properties in bacterial inactivation. This work presents a design fabrication of low-cost, layered TiO2 films assembled reactors and a study of their performance for a better understanding to elucidate the photocatalytic effect on inactivation of E. coli in water. The ability to reduce the number of bacteria in water samples for the layered TiO2 composing reactors has been investigated as a function of time, while varying the parameters of light sources, initial concentration of bacteria, and ratios of TiO2 film area and volume of water. Herein, the layered TiO2 films have been fabricated on the glass plates by thermal spray coating prior to screen printing, allowing a good adhesion of the films. Surface topology and crystallographic phase of TiO2 for the screen-printed active layer have been characterized, resulting in the ratio of anatase:rutile being 80:20. Under exposure to sunlight and a given condition employed in this study, the optimized film area:water volume of 1:2.62 has shown a significant ability to reduce the E. coli cells in water samples. The ratio of surface area of photocatalytic active base to volume of water medium is believed to play a predominant role facilitating the cells inactivation. The kinetic rate of inactivation and its behavior are also described in terms of adsorption of reaction species at different contact times.

  19. Origin of visible-light sensitivity in N-doped TiO2 films

    International Nuclear Information System (INIS)

    Nakano, Yoshitaka; Morikawa, Takeshi; Ohwaki, Takeshi; Taga, Yasunori

    2007-01-01

    We report on visible-light sensitivity in N-doped TiO 2 (TiO 2 :N) films that were deposited on n + -GaN/Al 2 O 3 substrates by reactive magnetron sputtering and subsequently crystallized by annealing at 550 deg. C in flowing N 2 gas. The N-doping concentration was ∼8.8%, as determined by X-ray photoelectron spectroscopy measurements. From transmission electron microscopic observations and optical absorption measurements, yellow-colored TiO 2 :N samples showed an enhanced granular structure and strong absorption in the visible-light region. Photoelectron spectroscopy in air measurements showed a noticeable decrease in ionization energy of TiO 2 by the N doping. Deep-level optical spectroscopy measurements revealed two characteristic deep levels located at ∼1.18 and ∼2.48 eV below the conduction band. The 1.18 eV level is probably attributable to the O vacancy state and can be active as an efficient generation-recombination center. The pronounced 2.48 eV band is newly introduced by the N doping and contributes to band-gap narrowing of TiO 2 by mixing with the O 2p valence band. Therefore, this localized intraband is probably one origin of visible-light sensitivity in TiO 2 :N

  20. Hydrothermal synthesis spherical TiO2 and its photo-degradation property on salicylic acid

    International Nuclear Information System (INIS)

    Guo Wenlu; Liu Xiaolin; Huo Pengwei; Gao Xun; Wu Di; Lu Ziyang; Yan Yongsheng

    2012-01-01

    Anatase TiO 2 spheres have been prepared using hydrothermal synthesis. The prepared spheres were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and UV-vis diffuse reflectance spectra (UV-vis DRS). The TiO 2 consisted of well-defined spheres with size of 3-5 μm. The photocatalytic activity of spherical TiO 2 was determined by degradation of salicylic acid under visible light irradiation. It was revealed that the degradation rate of the spherical TiO 2 which was processed at 150 °C for 48 h could reach 81.758%. And the kinetics of photocatalytic degradation obeyed first-order kinetic, which the rate constant value was 0.01716 S -1 of the salicylic acid onto TiO 2 (temperature: 150, time: 48 h). The kinetics of adsorption followed the pseudo-second-order model and the rate constant was 1.2695 g mg -1 of the salicylic acid onto TiO 2 (temperature: 150, time: 48 h).