VO2/TiO2 Nanosponges as Binder-Free Electrodes for High-Performance Supercapacitors.

Science.gov (United States)

Hu, Chenchen; Xu, Henghui; Liu, Xiaoxiao; Zou, Feng; Qie, Long; Huang, Yunhui; Hu, Xianluo

2015-11-04

VO2/TiO2 nanosponges with easily tailored nanoarchitectures and composition were synthesized by electrostatic spray deposition as binder-free electrodes for supercapacitors. Benefiting from the unique interconnected pore network of the VO2/TiO2 electrodes and the synergistic effect of high-capacity VO2 and stable TiO2, the as-formed binder-free VO2/TiO2 electrode exhibits a high capacity of 86.2 mF cm(-2) (~548 F g(-1)) and satisfactory cyclability with 84.3% retention after 1000 cycles. This work offers an effective and facile strategy for fabricating additive-free composites as high-performance electrodes for supercapacitors.

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...

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

Directory of Open Access Journals (Sweden)

Sheen Mers SV

2015-10-01

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

Efficient Photocatalytic H2 Evolution: Controlled Dewetting-Dealloying to Fabricate Site-Selective High-Activity Nanoporous Au Particles on Highly Ordered TiO2 Nanotube Arrays.

Science.gov (United States)

Nguyen, Nhat Truong; Altomare, Marco; Yoo, JeongEun; Schmuki, Patrik

2015-05-27

Anodic self-organized TiO2 nanostumps are formed and exploited for self-ordering dewetting of Au-Ag sputtered films. This forms ordered particle configurations at the tube top (crown position) or bottom (ground position). By dealloying from a minimal amount of noble metal, porous Au nanoparticles are then formed, which, when in the crown position, allow for a drastically improved photocatalytic H2 production compared with nanoparticles produced by conventional dewetting processes. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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)

Pseudocapacitance of amorphous TiO2@nitrogen doped graphene composite for high rate lithium storage

International Nuclear Information System (INIS)

Li, Sheng; Xue, Pan; Lai, Chao; Qiu, Jingxia; Ling, Min; Zhang, Shanqing

2015-01-01

The high rate applications such as electric vehicles of the traditional lithium ion batteries (LIBs) are commonly limited by their insufficient electron conductivity and slow mass transport of lithium ions in bulk electrode materials. In order to address these issues, in this work, a simple and up-scalable wet-mechanochemical (wet-ball milling) route has been developed for fabrication of amorphous porous TiO 2 @nitrogen doped graphene (TiO 2 @N-G) nanocomposites. The amorphous phase, unique porous structure of TiO 2 and the surface defects from nitrogen doping to graphene planes have incurred surface controlled reactions, contributing pseudocapacitance to the total capacity of the battery. It plays a dominant role in producing outstanding high rate electrochemical performance, e.g., 182.7 mAh/g (at 3.36 A/g) after 100 cycles. The design and synthesis of electrode materials with enhanced conductivity and surface pseudocapacitance can be a promising way for high rate LIBs.

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

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

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.

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

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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.

Photocatalytic activity of TiO2/Nb2O5/PANI and TiO2/Nb2O5/RGO as new nanocomposites for degradation of organic pollutants.

Science.gov (United States)

Zarrin, Saviz; Heshmatpour, Felora

2018-06-05

In this study, highly active titanium dioxide modified by niobium oxide (Nb 2 O 5 ), polymer (PANI) and reduced graphene oxide (RGO) were successfully prepared. The morphology, structure, surface area and light absorption properties of the present nanocomposites for removal of methylene blue (MB) and methyl orange (MO) were investigated and compared with those of TiO 2 /Nb 2 O 5 and TiO 2 nanoparticles. The characterization techniques such as XRD, FT-IR, UV-vis, SEM, EDX, BET and TEM were employed in order to identify the nanocomposites. Also, photocatalytic properties of TiO 2 /Nb 2 O 5 /PANI and TiO 2 /Nb 2 O 5 /RGO nanocomposites under visible light irradiation were studied. In this way, the obtained results were compared to each other and also compared to TiO 2 /Nb 2 O 5 and TiO 2 nanoparticles. In this context, the chemical oxygen demand (COD) removal follows the photodegradation in observed performance. The results indicate that reduced TiO 2 /Nb 2 O 5 nanocomposite is effectively modified by graphene oxide to give TiO 2 /Nb 2 O 5 /RGO composite. The TiO 2 /Nb 2 O 5 /RGO exhibits significantly higher photocatalytic activity in degradation of organic dyes under visible light rather than that of TiO 2 /Nb 2 O 5 /PANI, TiO 2 /Nb 2 O 5 and pure TiO 2 . Copyright © 2018 Elsevier B.V. All rights reserved.

Highly stable colloidal TiO2 nanocrystals with strong violet-blue emission

International Nuclear Information System (INIS)

Ghamsari, Morteza Sasani; Gaeeni, Mohammad Reza; Han, Wooje; Park, Hyung-Ho

2016-01-01

Improved sol–gel method has been applied to prepare highly stable colloidal TiO 2 nanocrystals. The synthesized titania nanocrystals exhibit strong emission in the violet-blue wavelength region. Very long evolution time was obtained by preventing the sol to gel conversion with reflux process. FTIR, XRD, UV–vis absorption, photoluminescence and high resolution transmission electron microscope (HRTEM) were used to study the optical properties, crystalline phase, morphology, shape and size of prepared TiO 2 colloidal nanocrystals. HRTEM showed that the diameter of TiO 2 colloidal nanocrystals is about 5 nm. Although the PL spectra show similar spectral features upon excitation wavelengths at 280, 300 and 350 nm, but their emission intensities are significantly different from each other. Photoluminescence quantum yield for TiO 2 colloidal nanocrystals is estimated to be 49% with 280 nm excitation wavelength which is in agreement and better than reported before. Obtained results confirm that the prepared colloidal TiO 2 sample has enough potential for optoelectronics applications.

Supported noble metals on hydrogen-treated TiO2 nanotube arrays as highly ordered electrodes for fuel cells.

Science.gov (United States)

Zhang, Changkun; Yu, Hongmei; Li, Yongkun; Gao, Yuan; Zhao, Yun; Song, Wei; Shao, Zhigang; Yi, Baolian

2013-04-01

Hydrogen-treated TiO2 nanotube (H-TNT) arrays serve as highly ordered nanostructured electrode supports, which are able to significantly improve the electrochemical performance and durability of fuel cells. The electrical conductivity of H-TNTs increases by approximately one order of magnitude in comparison to air-treated TNTs. The increase in the number of oxygen vacancies and hydroxyl groups on the H-TNTs help to anchor a greater number of Pt atoms during Pt electrodeposition. The H-TNTs are pretreated by using a successive ion adsorption and reaction (SIAR) method that enhances the loading and dispersion of Pt catalysts when electrodeposited. In the SIAR method a Pd activator can be used to provide uniform nucleation sites for Pt and leads to increased Pt loading on the H-TNTs. Furthermore, fabricated Pt nanoparticles with a diameter of 3.4 nm are located uniformly around the pretreated H-TNT support. The as-prepared and highly ordered electrodes exhibit excellent stability during accelerated durability tests, particularly for the H-TNT-loaded Pt catalysts that have been annealed in ultrahigh purity H2 for a second time. There is minimal decrease in the electrochemical surface area of the as-prepared electrode after 1000 cycles compared to a 68 % decrease for the commercial JM 20 % Pt/C electrode after 800 cycles. X-ray photoelectron spectroscopy shows that after the H-TNT-loaded Pt catalysts are annealed in H2 for the second time, the strong metal-support interaction between the H-TNTs and the Pt catalysts enhances the electrochemical stability of the electrodes. Fuel-cell testing shows that the power density reaches a maximum of 500 mWcm(-2) when this highly ordered electrode is used as the anode. When used as the cathode in a fuel cell with extra-low Pt loading, the new electrode generates a specific power density of 2.68 kWg(Pt) (-1) . It is indicated that H-TNT arrays, which have highly ordered nanostructures, could be used as ordered electrode supports

Ordering of Zn-centered porphyrin and phthalocyanine on TiO2(011: STM studies

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Piotr Olszowski

2017-01-01

Full Text Available Zn(IIphthalocyanine molecules (ZnPc were thermally deposited on a rutile TiO2(011 surface and on Zn(IImeso-tetraphenylporphyrin (ZnTPP wetting layers at room temperature and after elevated temperature thermal processing. The molecular homo- and heterostructures were characterized by high-resolution scanning tunneling microscopy (STM at room temperature and their geometrical arrangement and degree of ordering are compared with the previously studied copper phthalocyanine (CuPc and ZnTPP heterostructures. It was found that the central metal atom may play some role in ordering and growth of phthalocyanine/ZnTPP heterostructures, causing differences in stability of upright standing ZnPc versus CuPc molecular chains at given thermal annealing conditions.

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

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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.

Fast fabrication of long TiO2 nanotube array with high photoelectrochemical property on flexible stainless steel.

Science.gov (United States)

Tao, Jie; Wu, Tao; Gao, Peng

2012-03-01

Oriented highly ordered long TiO2 nanotube array films with nanopore structure and high photoelectrochemical property were fabricated on flexible stainless steel substrate (50 microm) by anodization treatment of titanium thin films in a short time. The samples were characterized by means of field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and photoelectrochemical methods, respectively. The results showed that Ti films deposited at the condition of 0.7 Pa Ar pressure and 96 W sputtering power at room temperature was uniform and dense with good homogeneity and high crystallinity. The voltage and the anodization time both played significant roles in the formation of TiO2 nanopore-nanotube array film. The optimal voltage was 60 V and the anodization time is less than 30 min by anodizing Ti films in ethylene glycerol containing 0.5% (w) NH4F and 3% (w) H2O. The growth rate of TiO2 nanotube array was as high as 340 nm/min. Moreover, the photocurrent-potential curves, photocurrent response curves and electrochemical impedance spectra results indicated that the TiO2 nanotube array film with the nanoporous structure exhibited a better photo-response ability and photoelectrochemical performance than the ordinary TiO2 nanotube array film. The reason is that the nanoporous structure on the surface of the nanotube array can separate the photo electron-hole pairs more efficiently and completely than the tubular structure.

An internal magnetic field strategy to reuse pulverized active materials for high performance: a magnetic three-dimensional ordered macroporous TiO2/CoPt/α-Fe2O3 nanocomposite anode.

Science.gov (United States)

Tang, Yiping; Hong, Liang; Li, Jiquan; Hou, Guangya; Cao, Huazhen; Wu, Liankui; Zheng, Guoqu; Wu, Qingliu

2017-05-09

A ferromagnetic three-dimensional ordered macroporous TiO 2 /CoPt/α-Fe 2 O 3 (3DOMTCF) nanocomposite was synthesized via a sol-gel approach templated by poly(methyl methacrylate) (PMMA) microspheres. After magnetization, it exhibited an extremely high reversible capacity and a long cycle life, which were ascribed to the internal magnetic field for reusing pulverized active materials and its unique structure.

Sandwich structured MoO2@TiO2@CNT nanocomposites with high-rate performance for lithium ion batteries

International Nuclear Information System (INIS)

Yuan, Dandan; Yang, Wanli; Ni, Jiangfeng; Gao, Lijun

2015-01-01

Titanium dioxide (TiO 2 ) is an important anode candidate for Li-ion battery (LIB) due to its properties of excellent cycle, high safety and low cost. However, the poor electrical conductivity of TiO 2 presents a significant challenge hampering its practical application in LIBs. Most researches have been concentrated on developing TiO 2 composites with metals, metal oxides and carbonaceous materials to improve its conductivity. In this work, we investigated a sandwich structured MoO 2 @TiO 2 @CNT nanocomposite through a simple three-step synthesis method. The CNT and highly conductive MoO 2 under/on the TiO 2 layer are served as flexible and strong electronic paths for rapid electron and ion transport. The resulting MoO 2 @TiO 2 @CNT hybrid structures show improved specific capacity and cycling stability compared with TiO 2 @CNT. In addition, the MoO 2 @TiO 2 @CNT composites also show a favorable rate capability, demonstrating its potential as anode material for LIBs

Photocatalytic Oxidation of Acetone Over High Thermally Stable TiO2 Nanosheets With Exposed (001) Facets.

Science.gov (United States)

Shi, Ting; Duan, Youyu; Lv, Kangle; Hu, Zhao; Li, Qin; Li, Mei; Li, Xiaofang

2018-01-01

Anatase TiO 2 (A-TiO 2 ) usually exhibits superior photocatalytic activity than rutile TiO 2 (R-TiO 2 ). However, the phase transformation from A-TiO 2 to R-TiO 2 will inevitably happens when the calcination temperature is up to 600°C, which hampers the practical applications of TiO 2 photocatalysis in hyperthermal situations. In this paper, high energy faceted TiO 2 nanosheets (TiO 2 -NSs) with super thermal stability was prepared by calcination of TiOF 2 cubes. With increase in the calcination temperature from 300 to 600°C, TiOF 2 transforms into TiO 2 hollow nanoboxes (TiO 2 -HNBs) assembly from TiO 2 -NSs via Ostwald Rippening process. Almost all of the TiO 2 -HNBs are disassembled into discrete TiO 2 -NSs when calcination temperature is higher than 700°C. Phase transformation from A-TiO 2 to R-TiO 2 begins at 1000°C. Only when the calcination temperature is higher than 1200°C can all the TiO 2 -NSs transforms into R-TiO 2 . The 500°C-calcined sample (T500) exhibits the highest photoreactivity toward acetone oxidation possibly because of the production of high energy TiO 2 -NSs with exposed high energy (001) facets and the surface adsorbed fluorine. Surface oxygen vacancy, due to the heat-induced removal of surface adsorbed fluoride ions, is responsible for the high thermal stability of TiO 2 -NSs which are prepared by calcination of TiOF 2 cubes.

High surface area TiO2/SBA-15 nanocomposites: Synthesis, microstructure and adsorption-enhanced photocatalysis

Science.gov (United States)

Wei, J. Q.; Chen, X. J.; Wang, P. F.; Han, Y. B.; Xu, J. C.; Hong, B.; Jin, H. X.; Jin, D. F.; Peng, X. L.; Li, J.; Yang, Y. T.; Ge, H. L.; Wang, X. Q.

2018-06-01

Mesoporous SBA-15 was used to anchor TiO2 nanoparticles into the mesopores to form high surface area TiO2/SBA-15 nanocomposites, and then the influence of mesoporous-structure on the photocatalytic performance was investigated. TiO2/SBA-15 nanocomposites possessed the high specific surface area and appropriate pore size, indicating the excellent adsorption performance. TiO2/SBA-15 nanocomposites exhibited the higher photocatalytic activity to degrade dyes (methylene blue: MB) than TiO2 (removing SBA-15), which should attributed to the excellent adsorption performance of the nanocomposites. MB was absorbed to form the higher concentration near TiO2/SBA-15 photocatalysts, and the photocatalytic degradation for MB was improved.

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 ...

Investigations of percutaneous uptake of ultrafine TiO2 particles at the high energy ion nanoprobe LIPSION

International Nuclear Information System (INIS)

Menzel, F.; Reinert, T.; Vogt, J.; Butz, T.

2004-01-01

Micronised TiO 2 particles with a diameter of about 15 nm are used in sunscreens as physical UV filter. Due to the small particle size it may be supposed that TiO 2 particles can pass through the uppermost horny skin layer (stratum corneum) via intercellular channels and penetrate into deeper vital skin layers. Accumulations of TiO 2 particles in the skin can decrease the threshold for allergies of the immune system or cause allergic reactions directly. Spatially resolved ion beam analysis (PIXE, RBS, STIM and secondary electron imaging) was carried out on freeze-dried cross-sections of biopsies of pig skin, on which four different formulations containing TiO 2 particles were applied. The investigations were carried out at the high energy ion nanoprobe LIPSION in Leipzig with a 2.25 MeV proton beam, which was focused to a diameter of 1 μm. The analysis concentrated on the penetration depth and on pathways of the TiO 2 particles into the skin. In these measurements a penetration of TiO 2 particles through the s. corneum into the underlying stratum granulosum via intercellular space was found. Hair follicles do not seem to be important penetration pathways because no TiO 2 was detected inside. The TiO 2 particle concentration in the stratum spinosum was below the minimum detection limit of about 1 particle/μm 2 . These findings show the importance of coating the TiO 2 particles in order to prevent damage of RNA and DNA of skin cells by photocatalytic reactions of the penetrated particles caused by absorption of UV light

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.

Photocatalytic Degradation of Chlorobenzene by TiO2 in High-Temperature and High-Pressure Water

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N. Kometani

2008-01-01

Full Text Available A fluidized-bed-type flow reactor available for the photocatalytic treatment of the suspension of model soil under high-temperature, high-pressure conditions was designed. An aqueous suspension containing hydrogen peroxide (H2O2 as an oxidizer and inorganic oxides as a model soil, titania (TiO2, silica (SiO2, or kaoline (Al2Si2O5(OH4 was continuously fed into the reactor with the temperature and the pressure controlled to be T=20–400∘C and P = 30 MPa, respectively. The degradation of chlorobenzene (CB in water was chosen as a model oxidation reaction. It appeared that most of the model soils are not so harmful to the SCWO treatment of CB in solutions. When the TiO2 suspension containing H2O2 was irradiated with near-UV light, the promotion of the degradation caused by photocatalytic actions of TiO2 was observed at all temperatures. Persistence of the photocatalytic activity in the oxidation reaction in high-temperature, high-pressure water would open up a possibility of the development of the hybrid process based on the combination of SCWO process and TiO2 photocatalysis for the treatment of environmental pollutants in soil and water, which are difficult to handle by conventional SCWO process or catalytic SCWO process alone.

Highly Efficient Light-Driven TiO2-Au Janus Micromotors.

Science.gov (United States)

Dong, Renfeng; Zhang, Qilu; Gao, Wei; Pei, Allen; Ren, Biye

2016-01-26

A highly efficient light-driven photocatalytic TiO2-Au Janus micromotor with wireless steering and velocity control is described. Unlike chemically propelled micromotors which commonly require the addition of surfactants or toxic chemical fuels, the fuel-free Janus micromotor (diameter ∼1.0 μm) can be powered in pure water under an extremely low ultraviolet light intensity (2.5 × 10(-3) W/cm(2)), and with 40 × 10(-3) W/cm(2), they can reach a high speed of 25 body length/s, which is comparable to common Pt-based chemically induced self-electrophoretic Janus micromotors. The photocatalytic propulsion can be switched on and off by incident light modulation. In addition, the speed of the photocatalytic TiO2-Au Janus micromotor can be accelerated by increasing the light intensity or by adding low concentrations of chemical fuel H2O2 (i.e., 0.1%). The attractive fuel-free propulsion performance, fast movement triggering response, low light energy requirement, and precise motion control of the TiO2-Au Janus photocatalytic micromotor hold considerable promise for diverse practical applications.

Plasma-spraying synthesis of high-performance photocatalytic TiO2 coatings

International Nuclear Information System (INIS)

Takahashi, Yasuo; Maeda, Masakatsu; Ohmori, Akira; Shibata, Yoshitaka; Miyano, Yasuyuki; Murai, Kensuke

2014-01-01

Anatase (A-) TiO 2 is a photocatalytic material that can decompose air-pollutants, acetaldehyde, bacteria, and so on. In this study, three kinds of powder (A-TiO 2 without HAp, TiO 2 + 10mass%HAp, and TiO 2 +30mass%HAp, where HAp is hydroxyapatite and PBS is polybutylene succinate) were plasma sprayed on biodegradable PBS substrates. HAp powder was mixed with A-TiO 2 powder by spray granulation in order to facilitate adsorption of acetaldehyde and bacteria. The crystal structure was almost completely maintained during the plasma spray process. HAp enhanced the decomposition of acetaldehyde and bacteria by promoting adsorption. A 10mass% HAp content was the most effective for decomposing acetaldehyde when plasma preheating of the PBS was not carried out before the plasma spraying. The plasma preheating of PBS increased the yield rate of the spray process and facilitated the decomposition of acetaldehyde by A-TiO 2 coatings without HAp. HAp addition improved photocatalytic sterilization when plasma preheating of the PBS was performed

A Facile Method for Loading CeO2 Nanoparticles on Anodic TiO2 Nanotube Arrays.

Science.gov (United States)

Liao, Yulong; Yuan, Botao; Zhang, Dainan; Wang, Xiaoyi; Li, Yuanxun; Wen, Qiye; Zhang, Huaiwu; Zhong, Zhiyong

2018-04-03

In this paper, a facile method was proposed to load CeO 2 nanoparticles (NPs) on anodic TiO 2 nanotube (NT) arrays, which leads to a formation of CeO 2 /TiO 2 heterojunctions. Highly ordered anatase phase TiO 2 NT arrays were fabricated by using anodic oxidation method, then these individual TiO 2 NTs were used as tiny "nano-containers" to load a small amount of Ce(NO 3 ) 3 solutions. The loaded anodic TiO 2 NTs were baked and heated to a high temperature of 450 °C, under which the Ce(NO 3 ) 3 would be thermally decomposed inside those nano-containers. After the thermal decomposition of Ce(NO 3 ) 3 , cubic crystal CeO 2 NPs were obtained and successfully loaded into the anodic TiO 2 NT arrays. The prepared CeO 2 /TiO 2 heterojunction structures were characterized by a variety of analytical technologies, including XRD, SEM, and Raman spectra. This study provides a facile approach to prepare CeO 2 /TiO 2 films, which could be very useful for environmental and energy-related areas.

Comparative study of A-site order in the lead-free bismuth titanates M1/2Bi1/2TiO3 (M=Li, Na, K, Rb, Cs, Ag, Tl) from first-principles

International Nuclear Information System (INIS)

Gröting, Melanie; Albe, Karsten

2014-01-01

We investigate the possibility of enhancing chemical order in the relaxor ferroelectric Na 1/2 Bi 1/2 TiO 3 upon substitution of Na + by other monovalent cations M + using total energy calculations based on density functional theory. All chemically available monovalent cations M + , which are Li, Na, Ag, K, Tl, Rb and Cs, are considered and an analysis of the structurally relaxed structures in terms of symmetry-adapted distortion modes is given in order to quantify the chemically induced structural distortions. We demonstrate that the replacement of Na + by other monovalent cations can hardly alter the tendency of chemical order with respect to Na 1/2 Bi 1/2 TiO 3 . Only Tl 1/2 Bi 1/2 TiO 3 and Ag 1/2 Bi 1/2 TiO 3 show enhanced tendency for chemical ordering. Both heavy metals behave similar to the light alkali metals in terms of structural relaxations and relative stabilities of the ordered configurations. Although a comparison of the Goldschmidt factors of components (M TiO 3 ) − reveals for Tl a value above the upper stability limit for perovskites, the additional lone-pair effect of Tl + stabilizes the ordered structure. - Graphical abstract: Amplitudes of chemically induced distortion modes in different ordered perovskites M 1/2 Bi 1/2 TiO 3 and visualisation of atomic displacements associated with distortion mode X + 1 in the 001-ordered compounds Li 1/2 Bi 1/2 TiO 3 and Cs 1/2 Bi 1/2 TiO 3 . Due to a substantial size mismatch between bismuth (green) and caesium (dark blue), incorporation of the latter leads to enhanced displacements of oxygen atoms (red) and suppresses displacements of titanium (silver) as compared to lithium (light blue) or other smaller monovalent cations. - Highlights: • Lead-free A-site mixed bismuth titanates M 1/2 Bi 1/2 TiO 3 are studied by first-principles calculations. • Investigation of chemical ordering tendency for M=Li, Na, K, Rb, Cs, Ag, and Tl. • Group theoretical analysis of different ordered structures. • Ag and Tl

TiO2-ITO and TiO2-ZnO nanocomposites: application on water treatment

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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.

Nanostructured TiO2 Doped with Nb as a Novel Support for PEMFC

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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.

Electron microscopy observation of TiO2 nanocrystal evolution in high-temperature atomic layer deposition.

Science.gov (United States)

Shi, Jian; Li, Zhaodong; Kvit, Alexander; Krylyuk, Sergiy; Davydov, Albert V; Wang, Xudong

2013-01-01

Understanding the evolution of amorphous and crystalline phases during atomic layer deposition (ALD) is essential for creating high quality dielectrics, multifunctional films/coatings, and predictable surface functionalization. Through comprehensive atomistic electron microscopy study of ALD TiO2 nanostructures at designed growth cycles, we revealed the transformation process and sequence of atom arrangement during TiO2 ALD growth. Evolution of TiO2 nanostructures in ALD was found following a path from amorphous layers to amorphous particles to metastable crystallites and ultimately to stable crystalline forms. Such a phase evolution is a manifestation of the Ostwald-Lussac Law, which governs the advent sequence and amount ratio of different phases in high-temperature TiO2 ALD nanostructures. The amorphous-crystalline mixture also enables a unique anisotropic crystal growth behavior at high temperature forming TiO2 nanorods via the principle of vapor-phase oriented attachment.

High-resolution photoelectron spectroscopy of TiO3H2-: Probing the TiO2- + H2O dissociative adduct

Science.gov (United States)

DeVine, Jessalyn A.; Abou Taka, Ali; Babin, Mark C.; Weichman, Marissa L.; Hratchian, Hrant P.; Neumark, Daniel M.

2018-06-01

Slow electron velocity-map imaging spectroscopy of cryogenically cooled TiO3H2- anions is used to probe the simplest titania/water reaction, TiO20/- + H2O. The resultant spectra show vibrationally resolved structure assigned to detachment from the cis-dihydroxide TiO(OH)2- geometry based on density functional theory calculations, demonstrating that for the reaction of the anionic TiO2- monomer with a single water molecule, the dissociative adduct (where the water is split) is energetically preferred over a molecularly adsorbed geometry. This work represents a significant improvement in resolution over previous measurements, yielding an electron affinity of 1.2529(4) eV as well as several vibrational frequencies for neutral TiO(OH)2. The energy resolution of the current results combined with photoelectron angular distributions reveals Herzberg-Teller coupling-induced transitions to Franck-Condon forbidden vibrational levels of the neutral ground state. A comparison to the previously measured spectrum of bare TiO2- indicates that reaction with water stabilizes neutral TiO2 more than the anion, providing insight into the fundamental chemical interactions between titania and water.

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.

A ₂ TiO ₅ (A = Dy, Gd, Er, Yb) at High Pressure

Energy Technology Data Exchange (ETDEWEB)

Park, Sulgiye [Department of Geological Science, Stanford University, Stanford, California 94305, United States; Rittman, Dylan R. [Department of Geological Science, Stanford University, Stanford, California 94305, United States; Tracy, Cameron L. [Department of Geological Science, Stanford University, Stanford, California 94305, United States; Chapman, Karena W. [X-ray Science Division, Advanced Photon; Zhang, Fuxiang [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States; Park, Changyong [HPCAT, Carnegie Institution of Washington, Argonne, Illinois 60439, United States; Tkachev, Sergey N. [Center for Advanced Radiation Sources, University of Chicago, Chicago, Illinois 60637, United States; O’Quinn, Eric [Department of Nuclear Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States; Shamblin, Jacob [Department of Nuclear Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States; Lang, Maik [Department of Nuclear Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States; Mao, Wendy L. [Department of Geological Science, Stanford University, Stanford, California 94305, United States; Stanford; amp, Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States; Ewing, Rodney C. [Department of Geological Science, Stanford University, Stanford, California 94305, United States

2018-02-07

The structural evolution of lanthanide A2TiO5 (A = Dy, Gd, Yb, and Er) at high pressure is investigated using synchrotron X-ray diffraction. The effects of A-site cation size and of the initial structure are systematically examined by varying the composition of the isostructural lanthanide titanates, and the structure of dysprosium titanate polymorphs (orthorhombic, hexagonal and cubic), respectively. All samples undergo irreversible high pressure phase transformations, but with different onset pressures depending on the initial structure. While individual phase exhibits different phase transformation histories, all samples commonly experience a sluggish transformation to a defect cotunnite-like (Pnma) phase for a certain pressure range. Orthorhombic Dy2TiO5 and Gd2TiO5 form P21am at pressures below 9 GPa and Pnma above 13 GPa. Pyrochlore-type Dy2TiO5 and Er2TiO5 as well as defect-fluorite-type Yb2TiO5 form Pnma at ~ 21 GPa, followed by Im-3m. Hexagonal Dy2TiO5 forms Pnma directly, although a small amount of remnants of hexagonal Dy2TiO5 is observed even at the highest pressure (~ 55 GPa) reached, indicating a kinetic limitations in the hexagonal Dy2TiO5 phase transformations at high pressure. Decompression of these materials leads to different metastable phases. Most interestingly, a high pressure cubic X-type phase (Im-3m) is confirmed using highresolution transmission electron microscopy on recovered pyrochlore-type Er2TiO5. The kinetic constraints on this metastable phase yield a mixture of both the X-type phase and amorphous domains upon pressure release. This is the first observation of an X-type phase for an A2BO5 composition at high pressure.

Integration of High-Performance Nanocrystalline TiO2 Photoelectrodes for N719-Sensitized Solar Cells

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Ke-Jian Jiang

2013-01-01

Full Text Available We report on enhanced performance of N719-sensitized TiO2 solar cells (DSCs incorporating size and photoelectron diffusion-controlled TiO2 as sensitizer-matched light-scatter layers on conventional nanocrystalline TiO2 electrodes. The double-layered N719/TiO2 composite electrode with a high dye-loading capacity exhibits the diffused reflectance of more than 50% in the range of λ = 650–800 nm, even when the films are coupled with the titania nanocrystalline underlayer in the device. As a result, the increased near-infrared light-harvesting produces a high light-to-electricity conversion efficiency of over 9% mainly due to the significant increase of Jsc. Such an optical effect of the NIR-light scattering TiO2 electrodes will be beneficial when the sensitizers with low molar extinction coefficients, such as N719, are introduced in the device.

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.

Hierarchical architectures of ZnS–In2S3 solid solution onto TiO2 nanofibers with high visible-light photocatalytic activity

International Nuclear Information System (INIS)

Liu, Chengbin; Meng, Deshui; Li, Yue; Wang, Longlu; Liu, Yutang; Luo, Shenglian

2015-01-01

Graphical abstract: A unique hierarchical architecture of ZnS–In 2 S 3 solid solution onto TiO 2 nanofibers was fabricated. The hierarchical heterostructures exhibit high visible light photocatalytic activity and outstanding recycling performance. - Highlights: • Novel hierarchical heterostructure of TiO 2 @ZnS–In 2 S 3 solid solution. • Efficient inhibition of ZnS–In 2 S 3 solid solution aggregation. • High visible light photocatalytic activity. • Highly stable recycling performance. - Abstract: A unique hierarchical architecture of ZnS–In 2 S 3 solid solution nanostructures onto TiO 2 nanofibers (TiO 2 @ZnS–In 2 S 3 ) has been successfully fabricated by simple hydrothermal method. The ZnS–In 2 S 3 solid solution nanostructures exhibit a diversity of morphologies: nanosheet, nanorod and nanoparticle. The porous TiO 2 nanofiber templates effectively inhibit the aggregation growth of ZnS–In 2 S 3 solid solution. The formation of ZnS–In 2 S 3 solid solution is proved by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) and the intimate contact between TiO 2 nanofibers and ZnS–In 2 S 3 solid solution favors fast transfer of photogenerated electrons. The trinary TiO 2 @ZnS–In 2 S 3 heterostructures exhibit high adsorption capacity and visible light photocatalytic activity for the degradation of rhodamine B dye (RhB), remarkably superior to pure TiO 2 nanofibers or binary structures (ZnS/TiO 2 nanofibers, In 2 S 3 /TiO 2 nanofibers and ZnS–In 2 S 3 solid solution). Under visible light irradiation the RhB photocatalytic degradation rate over TiO 2 @ZnS–In 2 S 3 heterostructures is about 16.7, 12.5, 6.3, 5.9, and 2.2 times that over pure TiO 2 nanofibers, ZnS nanoparticles, In 2 S 3 /TiO 2 nanofibers, ZnS/TiO 2 nanofibers, and ZnS-In 2 S 3 solid solution, respectively. Furthermore, the TiO 2 @ZnS–In 2 S 3 heterostructures show highly stable recycling performance

Development of high efficient visible light-driven N, S-codoped TiO2 nanowires photocatalysts

International Nuclear Information System (INIS)

Zhang, Yanlin; Liu, Peihong; Wu, Honghai

2015-01-01

Highlights: • A facile hydrothermal route to synthesize N, S-codoped TiO 2 nanowires. • The codoped TiO 2 nanowires have TiO 2 (B) and anatase phase. • The significant shift of the optical absorption edge toward the visible region. • The photocatalyst showed high photocatalytic activity for atrazine. - Abstract: One-dimensional (1D) nanowire material (especially nonmetal doped 1D nanowires) synthesized by a facile way is of great significance and greatly desired as it has higher charge carrier mobility and lower carrier recombination rate. N, S-codoped TiO 2 nanowires were synthesized using titanium sulfate as a precursor and isopropanol as a protective capping agent by a hydrothermal route. The obtained doped nanowires were characterized by XRD, SEM, HRTEM, SAED, XPS, BET and UV–vis absorption spectrum. The incorporation of N and S into TiO 2 NWs can lead to the expansion of its lattice and remarkably lower its electron-transfer resistance. Photocatalytic activity measurement showed that the N, S-codoped TiO 2 nanowires with high quantum efficiency revealed the best photocatalytic performance for atrazine degradation under visible light irradiation compared to N, S-codoped TiO 2 nanoparticles and S-doped TiO 2 nanowires, which was attributed to (i) the synergistic effect of N and S doping in narrowing the band gap, separating electron–hole pairs and increasing the photoinduced electrons, and (ii) extending the anatase-to-rutile transformation temperature above 600 °C

TiO2 nanorods/PMMA copolymer-based nanocomposites: highly homogeneous linear and nonlinear optical material

International Nuclear Information System (INIS)

Sciancalepore, C; Agostiano, A; Cassano, T; Valentini, A; Curri, M L; Striccoli, M; Mecerreyes, D; Tommasi, R

2008-01-01

Original nanocomposites have been obtained by direct incorporation of pre-synthesized oleic acid capped TiO 2 nanorods into properly functionalized poly(methyl methacrylate) copolymers, carrying carboxylic acid groups on the repeating polymer unit. The presence of carboxylic groups on the alkyl chain of the host functionalized copolymer allows an highly homogeneous dispersion of the nanorods in the organic matrix. The prepared TiO 2 /PMMA-co-MA nanocomposites show high optical transparency in the visible region, even at high TiO 2 nanorod content, and tunable linear refractive index depending on the nanoparticle concentration. Finally measurements of nonlinear optical properties of TiO 2 polymer nanocomposites demonstrate a negligible two-photon absorption and a negative value of nonlinear refractive index, highlighting the potential of the nanocomposite for efficient optical devices operating in the visible region

TiO2 nanorods/PMMA copolymer-based nanocomposites: highly homogeneous linear and nonlinear optical material

Science.gov (United States)

Sciancalepore, C.; Cassano, T.; Curri, M. L.; Mecerreyes, D.; Valentini, A.; Agostiano, A.; Tommasi, R.; Striccoli, M.

2008-05-01

Original nanocomposites have been obtained by direct incorporation of pre-synthesized oleic acid capped TiO2 nanorods into properly functionalized poly(methyl methacrylate) copolymers, carrying carboxylic acid groups on the repeating polymer unit. The presence of carboxylic groups on the alkyl chain of the host functionalized copolymer allows an highly homogeneous dispersion of the nanorods in the organic matrix. The prepared TiO2/PMMA-co-MA nanocomposites show high optical transparency in the visible region, even at high TiO2 nanorod content, and tunable linear refractive index depending on the nanoparticle concentration. Finally measurements of nonlinear optical properties of TiO2 polymer nanocomposites demonstrate a negligible two-photon absorption and a negative value of nonlinear refractive index, highlighting the potential of the nanocomposite for efficient optical devices operating in the visible region.

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

Science.gov (United States)

Lv, Jinze; Zhu, Lizhong

2013-01-01

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

EFFECT OF THE REDUCTION TEMPERATURE INTO CATALYTIC ACTIVITY OF Ni SUPPORTED BY TiO2, AL2O2 AND TiO2/AL2O3 FOR CONVERSION CO2 INTO METHANE

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Hery Haerudin

2010-06-01

Full Text Available Nickel catalysts, containing 6% (w/w of nickel, have been prepared using TiO2, Al2O3 and mixture of TiO2-Al2O3 (1:9. The catalysts were used for CO2 conversion into methane. The characteristics of catalysts were studied by determination of its specific surface area, temperature programmed reaction technique and X-ray diffraction. The specific surface area were varied slightly by different temperature of reduction, namely after reduction at 300°C it was 39, 120 and 113 m2/g and after reduction at 400°C it was 42, 135  and 120 m2/g for 6% nickel catalysts supported on TiO2, Al2O3 and mixture of TiO2-Al2O3 (1:9 respectively. Temperature program reaction studies (TPO and TPR showed that NiTiOx species were possibly formed during the pretreatments which has shown by the shift of its peak to the lower temperature on Ni catalyst, that supported on mixture of TiO2-Al2O3 compared with catalysts supported on individual TiO2 or Al2O3. The nickel species on reduced Ni catalysts supported on TiO2 and on mixture of TiO2-Al2O3 could be detected by X-ray diffraction. The catalyst's activities toward CH4 formation were affected by the reduction temperature. Activity for CH4 formation was decreased in the following order: Ni/ TiO2 > Ni/ TiO2: Al2O3 > Ni/ Al2O3 and Ni/ TiO2: Al2O3 > Ni/ TiO2> Ni/ Al2O3, when catalysts were reduced at 300°C or 400°C respectively. The CO2 conversion was decreased in the following order: Ni/ Al2O3 > Ni/ TiO2: Al2O3 > Ni/ TiO2 when catalysts were reduced at 300°C or 400°C respectively.   Keywords: nickel catalyst, carbondioxide, methane

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.

One-step synthesis of hierarchically porous hybrid TiO2 hollow spheres with high photocatalytic activity

Science.gov (United States)

Liu, Ruiping; Ren, Feng; Yang, Jinlin; Su, Weiming; Sun, Zhiming; Zhang, Lei; Wang, Chang-an

2016-03-01

Hierarchically porous hybrid TiO2 hollow spheres were solvothermally synthesized successfully by using tetrabutyl titanate as titanium precursor and hydrated metal sulfates as soft templates. The as-prepared TiO2 spheres with hierarchically pore structures and high specific surface area and pore volume consisted of highly crystallized anatase TiO2 nanocrystals hybridized with a small amount of metal oxide from the hydrated sulfate. The proposed hydrated-sulfate assisted solvothermal (HAS) synthesis strategy was demonstrated to be widely applicable to various systems. Evaluation of the hybrid TiO2 hollow spheres for the photo-decomposition of methyl orange (MO) under visible-light irradiation revealed that they exhibited excellent photocatalytic activity and durability.

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.

Enhancement of mechanical strength of TiO2/high-density polyethylene composites for bone repair with silane-coupling treatment

International Nuclear Information System (INIS)

Hashimoto, Masami; Takadama, Hiroaki; Mizuno, Mineo; Kokubo, Tadashi

2006-01-01

Mechanical properties of composites made up of high-density polyethylene (HDPE) and silanated TiO 2 particles for use as a bone-repairing material were investigated in comparison with those of the composites of HDPE with unsilanized TiO 2 particles. The interfacial morphology and interaction between silanated TiO 2 and HDPE were analyzed by means of Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). The absorption in spectral bands related to the carboxyl bond in the silane-coupling agent, the vinyl group in the HDPE, and the formation of the ether bond was studied in order to assess the influence of the silane-coupling agent. The SEM micrograph showed that the 'bridging effect' between HDPE and TiO 2 was brought about by the silane-coupling agent. The use of the silane-coupling agent and the increase of the hot-pressing pressure for shaping the composites facilitated the penetration of polymer into cavities between individual TiO 2 particles, which increased the density of the composite. Therefore, mechanical properties such as bending yield strength and Young's modulus increased from 49 MPa and 7.5 GPa to 65 MPa and 10 GPa, respectively, after the silane-coupling treatment and increase in the hot-pressing pressure

High Sensitivity Refractometer Based on TiO2-Coated Adiabatic Tapered Optical Fiber via ALD Technology

Science.gov (United States)

Zhu, Shan; Pang, Fufei; Huang, Sujuan; Zou, Fang; Guo, Qiang; Wen, Jianxiang; Wang, Tingyun

2016-01-01

Atomic layer deposition (ALD) technology is introduced to fabricate a high sensitivity refractometer based on an adiabatic tapered optical fiber. Different thicknesses of titanium dioxide (TiO2) nanofilm were coated around the tapered fiber precisely and uniformly under different deposition cycles. Attributed to the higher refractive index of the TiO2 nanofilm compared to that of silica, an asymmetric Fabry–Perot (F-P) resonator could be constructed along the fiber taper. The central wavelength of the F-P resonator could be controlled by adjusting the thickness of the TiO2 nanofilm. Such a F-P resonator is sensitive to changes in the surrounding refractive index (SRI), which is utilized to realize a high sensitivity refractometer. The refractometer developed by depositing 50.9-nm-thickness TiO2 on the tapered fiber shows SRI sensitivity as high as 7096 nm/RIU in the SRI range of 1.3373–1.3500. Due to TiO2’s advantages of high refractive index, lack of toxicity, and good biocompatibility, this refractometer is expected to have wide applications in the biochemical sensing field. PMID:27537885

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)

Rutile TiO2 thin films grown by reactive high power impulse magnetron sputtering

International Nuclear Information System (INIS)

Agnarsson, B.; Magnus, F.; Tryggvason, T.K.; Ingason, A.S.; Leosson, K.; Olafsson, S.; Gudmundsson, J.T.

2013-01-01

Thin TiO 2 films were grown on Si(001) substrates by reactive dc magnetron sputtering (dcMS) and high power impulse magnetron sputtering (HiPIMS) at temperatures ranging from 300 to 700 °C. Optical and structural properties of films were compared both before and after post-annealing using scanning electron microscopy, low angle X-ray reflection (XRR), grazing incidence X-ray diffractometry and spectroscopic ellipsometry. Both dcMS- and HiPIMS-grown films reveal polycrystalline rutile TiO 2 , even prior to post-annealing. The HiPIMS-grown films exhibit significantly larger grains compared to that of dcMC-grown films, approaching 100% of the film thickness for films grown at 700 °C. In addition, the XRR surface roughness of HiPIMS-grown films was significantly lower than that of dcMS-grown films over the whole temperature range 300–700 °C. Dispersion curves could only be obtained for the HiPIMS-grown films, which were shown to have a refractive index in the range of 2.7–2.85 at 500 nm. The results show that thin, rutile TiO 2 films, with high refractive index, can be obtained by HiPIMS at relatively low growth temperatures, without post-annealing. Furthermore, these films are smoother and show better optical characteristics than their dcMS-grown counterparts. - Highlights: • We demonstrate growth of rutile TiO 2 on Si (111) by high power impulse magnetron sputtering. • The films exhibit significantly larger grains than dc magnetron sputtered films • TiO 2 films with high refractive index are obtained without post-growth annealing

Development of high dispersed TiO2 paste for transparent screen-printable self-cleaning coatings on glass

International Nuclear Information System (INIS)

Wang Yuanhao; Lu, Lin; Yang Hongxing; Che Quande

2013-01-01

This paper reports a cheap and facile method to fabricate transparent self-cleaning coatings on glass by screen-printing high dispersed TiO 2 paste. Three kinds of ZrO 2 beads with diameter of 2, 1, and 0.1–0.2 mm were utilized to investigate their influence on the grinding and dispersion of the commercial TiO 2 powder in the ball mill. From the SEM images, surface profiler and transmittance spectrum it could be demonstrated that the smallest ZrO 2 bead with the diameter of 0.1–0.2 mm was the best candidate to disperse the TiO 2 powder into nanoscale size to make the high dispersed TiO 2 paste which was the key factor to achieve a smooth, high transparent TiO 2 coating. The surface wettability measurement showed that all the screen-printed coatings had super hydrophilic surfaces, which was independent to the surface morphology. However, the coating with the highest transparency showed the lowest photocatalytic activity which is mainly due to the light loss.

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

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.

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.

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.

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.

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

Sol-gel synthesis of TiO2-SiO2 photocatalyst for β-naphthol photodegradation

International Nuclear Information System (INIS)

Qourzal, S.; Barka, N.; Tamimi, M.; Assabbane, A.; Nounah, A.; Ihlal, A.; Ait-Ichou, Y.

2009-01-01

Silica gel supported titanium dioxide particles (TiO 2 -SiO 2 ) prepared by sol-gel method was as photocatalyst in the degradation of β-naphthol in water under UV-illumination. The prepared sample has been characterized by powder X-ray diffraction (XRD), infrared spectroscopy (IR) and scanning electron microscopy (SEM). The supported catalyst had large surface area and good sedimentation ability. The photodegradation rate of β-naphthol under UV-irradiation depended strongly on adsorption capacity of the catalyst, and the photoactivity of the supported catalyst was much higher than that of the pure titanium dioxides. The experiments were measured by high performance liquid chromatography (HPLC). The photodegradation rate of β-naphthol using 60% TiO 2 -SiO 2 particles was faster than that using TiO 2 'Degussa P-25', TiO 2 'PC-50' and TiO 2 'Aldrich' as photocatalyst by 2.7, 4 and 7.8 times, respectively. The kinetics of photocatalytic β-naphthol degradation was found to follow a pseudo-first-order rate law. The effect of the TiO 2 loading on the photoactivity of TiO 2 -SiO 2 particles was also discussed. With good photocatalytic activity under UV-irradiation and the ability to be readily separated from the reaction system, this novel kind of catalyst exhibited the potential effective in the treatment of organic pollutants in aqueous systems.

Facile synthesis of high-temperature (1000 °C) phase-stable rice-like anatase TiO2 nanocrystals

Science.gov (United States)

Lv, Lizhen; Chen, Qirong; Liu, Xiuyun; Wang, Miaomiao; Meng, Xiangfu

2015-05-01

High-temperature phase-stable rice-like anatase TiO2 nanocrystals were synthesized by one-pot solvothermal method using soluble titania xerogel and isopropyl alcohol (IPA) as the precursor and the solvent, respectively. Sample characterization was carried out by powder X-ray diffraction, high-resolution transmission electron microscopy, field emission scanning electron microscope, X-ray photoelectron spectroscopy, and N2 adsorption-desorption isotherms. The results showed that TiO2 nanocrystals had rice-like shapes with an average size of 5 nm in width and 35 nm in length. The BET surface area was 153 m2/g. Unexpectedly, the rice-like TiO2 nanocrystals exhibited high-temperature phase stability, which could remain as pure anatase phase after calcinations at 1000 °C. Growth mechanism investigation revealed that the IPA solvent played a key role in nucleation and growth of rice-like anatase TiO2 nanocrystals. The photodegradation of rhodamine B demonstrated that rice-like anatase TiO2 nanocrystals exhibited enhanced photocatalytic activity under visible light irradiation.

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.

Effects of deposition rates on laser damage threshold of TiO2/SiO2 high reflectors

International Nuclear Information System (INIS)

Yao Jianke; Xu Cheng; Ma Jianyong; Fang Ming; Fan Zhengxiu; Jin Yunxia; Zhao Yuanan; He Hongbo; Shao Jianda

2009-01-01

TiO 2 single layers and TiO 2 /SiO 2 high reflectors (HR) are prepared by electron beam evaporation at different TiO 2 deposition rates. It is found that the changes of properties of TiO 2 films with the increase of rate, such as the increase of refractive index and extinction coefficient and the decrease of physical thickness, lead to the spectrum shift and reflectivity bandwidth broadening of HR together with the increase of absorption and decrease of laser-induced damage threshold. The damages are found of different morphologies: a shallow pit to a seriously delaminated and deep crater, and the different amorphous-to-anatase-to-rutile phase transition processes detected by Raman study. The frequency shift of Raman vibration mode correlates with the strain in film. Energy dispersive X-ray analysis reveals that impurities and non-stoichiometric defects are two absorption initiations resulting to the laser-induced transformation.

Mechanochemical preparation of nanocrystalline TiO2 powders and their behavior at high temperatures

International Nuclear Information System (INIS)

Gajovic, A.; Furic, K.; Tomasic, N.; Popovic, S.; Skoko, Z.; Music, S.

2005-01-01

Nanocrystalline TiO 2 powders were prepared by high-energy ball-milling using zirconia vial and balls. The changes of microstructure caused by material processing were studied using Raman spectroscopy, X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). The milling of the starting TiO 2 powder (anatase + rutile in traces) induced phase transitions to high-pressure polymorph, TiO 2 II, and rutile. We found that the phase transition to TiO 2 II was initiated at the surface of the small particles, while transition to rutile started in their center. Changes in crystallite size during milling process were obtained by the Scherrer method, while the particle size changes were monitored by TEM. The kinetics of phase changes, a decrease in crystallite/particle size, as well as zirconia contamination depended on the powder-to-ball weight ratio. The starting powder and some selected ball-milled samples were investigated in situ by Raman spectroscopy and XRD at high temperatures (up to 1300 deg. C) to examine their behavior during the sintering process. A difference in the results obtained by these two techniques was explained in frame of basic physical properties characterizing both methods. The morphology of the final sinters was monitored by scanning electron microscopy (SEM)

Ordered Fe(II)Ti(IV)O3 Mixed Monolayer Oxide on Rutile TiO2(011).

Science.gov (United States)

Halpegamage, Sandamali; Ding, Pan; Gong, Xue-Qing; Batzill, Matthias

2015-08-25

Oxide monolayers supported or intermixed with an oxide support are potential nanocatalysts whose properties are determined by the interplay with the support. For fundamental studies of monolayer oxides on metal oxide supports, well-defined systems are needed, but so far, the synthesis of monolayer oxides with long-range order on single-crystal oxide surfaces is rare. Here, we show by a combination of scanning tunneling microscopy, photoemission spectroscopy, and density functional theory (DFT)-based computational analysis that the rutile TiO2(011) surface supports the formation of an ordered mixed FeTiO3 monolayer. Deposition of iron in a slightly oxidizing atmosphere (10(-8) Torr O2) and annealing to 300 °C results in a well-ordered surface structure with Fe in a 2+ charge state and Ti in a 4+ charge states. Low-energy ion scattering suggests that the cation surface composition is close to half Fe and half Ti. This surface is stable in ultrahigh vacuum to annealing temperatures of 300 °C before the iron is reduced. DFT simulations confirm that a surface structure with coverage of 50% FeO units is stable and forms an ordered structure. Although distinct from known bulk phases of the iron-titanium oxide systems, the FeTiO3 monolayer exhibits some resemblance to the ilmenite structure, which may suggest that a variety of different mixed oxide phases (of systems that exist in a bulk ilmenite phase) may be synthesized in this way on the rutile TiO2(011) substrate.

Photolithographically Patterned TiO2 Films for Electrolyte-Gated Transistors.

Science.gov (United States)

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

2016-06-15

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

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.

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

Hierarchical (0 0 1) facet anatase/rutile TiO2 heterojunction photoanode with enhanced photoelectrocatalytic performance

International Nuclear Information System (INIS)

Tian, Hongyi; Zhao, Guohua; Zhang, Ya-nan; Wang, Yanbin; Cao, Tongcheng

2013-01-01

Highlights: ► (0 0 1) facet TiO 2 photoanode with large surface area is reported for the first time. ► Ordered heterojunction further improves light absorption in (0 0 1) facet TiO 2 system. ► (0 0 1) facet TiO 2 photoanode possesses promoted photoelectrocatalytic performance. ► Photoelectrical enhancement mechanism is clarified by electrochemical methods. ► Photogenerated carrier and lifetime are remarkably enhanced by ingenious design. -- Abstract: A hierarchical heterojunction TiO 2 photoanode with large surface/body ratio is reported to exhibit high oxidation activity due to the constructing of anatase TiO 2 with exposed (0 0 1) facets. The mixed-phase photoanode is fabricated through surfactant-assisted anchoring ultrathin anatase nanosheets on vertically ordered rutile nanorod arrays. This cactaceae-like TiO 2 possesses high-exposed (0 0 1) facets outer layer, large specific surface area (375 m 2 g −1 ), efficient photo-to-current conversion (8.2%) and excellent photocatalytic ability to degrade bisphenol A. The greatly promoted photoelectric and photocatalytic performance results from the synergetic effects of the architecture design of high-active (0 0 1) facets and hierarchical heterojunctions. The mechanism analysis reveals that the remarkable increase of photogenerated carrier concentration (2.40 × 10 22 cm −3 ) improves photocatalytic activity, by virtue of constructing staggered energy levels, suppressing the recombination of electrons and holes, and extending the electron lifetime (133 ms)

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

Science.gov (United States)

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

2015-10-01

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

High quantum yield graphene quantum dots decorated TiO_2 nanotubes for enhancing photocatalytic activity

International Nuclear Information System (INIS)

Qu, Ailan; Xie, Haolong; Xu, Xinmei; Zhang, Yangyu; Wen, Shengwu; Cui, Yifan

2016-01-01

Highlights: • High concentration yellow GQDs and TiO_2 nanotubes were achieved by a simple and green method. • High quantum yield GQDs enhanced the photodegradation capacity of TiO_2 nanotube. • The catalytic performance of GQDs/TiO_2 depends on the GQDs loading. • The improved photocatalytic activity of GQDs/TiO_2 was attributed to three aspects. - Abstract: Graphene quantum dots (GQDs) with high quantum yield (about 23.6% at an excitation wavelength of 320 nm) and GQDs/TiO_2 nanotubes (GQDs/TiO_2 NTs) composites were achieved by a simple hydrothermal method at low temperature. Photoluminescence characterization showed that the GQDs exhibited the down-conversion PL features at excitation from 300 to 420 nm and up-conversion photoluminescence in the range of 600–800 nm. The photocatalytic activity of prepared GQDs/TiO_2 NTs composites on the degradation of methyl orange (MO) was significantly enhanced compared with that of pure TiO_2 nanotubes (TiO_2 NTs). For the composites coupling with 1.5%, 2.5% and 3.5% GQDs, the degradation of MO after 20 min irradiation under UV–vis light irradiation (λ = 380–780 nm) were 80.52%, 94.64% and 51.91%, respectively, which are much higher than that of pure TiO_2 NTs (35.41%). It was inferred from the results of characterization that the improved photocatalytic activity of the GQDs/TiO_2 NTs composites was attributed to the synergetic effect of up-conversion properties of the GQDs, enhanced visible light absorption and efficient separation of photogenerated electron-holes of the GQDs/TiO_2 composite.

Nanoplasmonically Engineered Interfaces on Amorphous TiO2 for Highly Efficient Photocatalysis in Hydrogen Evolution.

Science.gov (United States)

Liang, Huijun; Meng, Qiuxia; Wang, Xiaobing; Zhang, Hucheng; Wang, Jianji

2018-04-25

The nanoplasmonic metal-driven photocatalytic activity depends heavily on the spacing between metal nanoparticles (NPs) and semiconductors, and this work shows that ethylene glycol (EG) is an ideal candidate for interface spacer. Controlling the synthetic systems at pH 3, the composite of Ag NPs with EG-stabilized amorphous TiO 2 (Ag/TiO 2 -3) was synthesized by the facile light-induced reduction. It is verified that EG spacers can set up suitable geometric arrangement in the composite: the twin hydroxyls act as stabilizers to bind Ag NPs and TiO 2 together and the nonconductive alkyl chains consisting only of two CH 2 are able to separate the two building blocks completely and also provide the shortest channels for an efficient transfer of radiation energies to reach TiO 2 . Employed as photocatalysts in hydrogen evolution under visible light, amorphous TiO 2 hardly exhibits the catalytic activity due to high defect density, whereas Ag/TiO 2 -3 represents a remarkably high catalytic efficiency. The enhancement mechanism of the reaction rate is proposed by the analysis of the compositional, structural, and optical properties from a series of Ag/TiO 2 composites.

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.

Deliberate Design of TiO2 Nanostructures towards Superior Photovoltaic Cells.

Science.gov (United States)

Sun, Ziqi; Liao, Ting; Sheng, Liyuan; Kou, Liangzhi; Kim, Jung Ho; Dou, Shi Xue

2016-08-01

TiO2 nanostructures are being sought after as flexibly utilizable building blocks for the fabrication of the mesoporous thin-film photoelectrodes that are the heart of the third-generation photovoltaic devices, such as dye-sensitized solar cells (DSSCs), quantum-dot-sensitized solar cells (QDSSCs), and the recently promoted perovskite-type solar cells. Here, we report deliberate tailoring of TiO2 nanostructures for superior photovoltaic cells. Morphology engineering of TiO2 nanostructures is realized by designing synthetic protocols in which the precursor hydrolysis, crystal growth, and oligomer self-organization are precisely controlled. TiO2 nanostructures in forms varying from isolated nanocubes, nanorods, and cross-linked nanorods to complex hierarchical structures and shape-defined mesoporous micro-/nanostructures were successfully synthesized. The photoanodes made from the shape-defined mesoporous TiO2 microspheres and nanospindles presented superior performances, owing to the well-defined overall shapes and the inner ordered nanochannels, which allow not only a high amount of dye uptake, but also improved visible-light absorption. This study provides a new way to seek an optimal synthetic protocol to meet the required functionality of the nanomaterials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thermoelectric Properties in the TiO2/SnO2 System

Science.gov (United States)

Dynys, F.; Sayir, A.; Sehirlioglu, A.; Berger, M.

2009-01-01

Nanotechnology has provided a new interest in thermoelectric technology. A thermodynamically driven process is one approach in achieving nanostructures in bulk materials. TiO2/SnO2 system exhibits a large spinodal region with exceptional stable phase separated microstructures up to 1400 C. Fabricated TiO2/SnO2 nanocomposites exhibit n-type behavior with Seebeck coefficients greater than -300 .V/K. Composites exhibit good thermal conductance in the range of 7 to 1 W/mK. Dopant additions have not achieved high electrical conductivity (<1000 S/m). Formation of oxygen deficient composites, TixSn1-xO2-y, can change the electrical conductivity by four orders of magnitude. Achieving higher thermoelectric ZT by oxygen deficiency is being explored. Seebeck coeffcient, thermal conductivity, electrical conductance and microstructure will be discussed in relation to composition and doping.

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.%.

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

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.

Highly piezoelectric BaTiO3 nanorod bundle arrays using epitaxially grown TiO2 nanomaterials.

Science.gov (United States)

Jang, Seon-Min; Yang, Su Chul

2018-06-08

Low-dimensional piezoelectric nanostructures such as nanoparticles, nanotubes, nanowires, nanoribbons and nanosheets have been developed for potential applications as energy harvesters, tunable sensors, functional transducers and low-power actuators. In this study, lead-free BaTiO 3 nanorod bundle arrays (NBA) with highly piezoelectric properties were successfully synthesized on fluorine-doped tin oxide (FTO) substrate via a two-step process consisting of TiO 2 epitaxial growth and BaTiO 3 conversion. Through the TiO 2 epitaxial growth on FTO substrate, (001) oriented TiO 2 nanostructures formed vertically-aligned NBA with a bundle diameter of 80 nm and an aspect ratio of six. In particular, chemical etching of the TiO 2 NBA was conducted to enlarge the surface area for effective Ba 2+ ion diffusion during the perovskite conversion process from TiO 2 to BaTiO 3 . The final structure of perovskite BaTiO 3 NBA was found to exhibit a feasible piezoelectric response of 3.56 nm with a clear phase change of 180° from the single BaTiO 3 bundle, by point piezoelectric forced microscopy (PFM) analysis. Consequently, highly piezoelectric NBA could be a promising nanostructure for various nanoscale electronic devices.

Highly piezoelectric BaTiO3 nanorod bundle arrays using epitaxially grown TiO2 nanomaterials

Science.gov (United States)

Jang, Seon-Min; Yang, Su Chul

2018-06-01

Low-dimensional piezoelectric nanostructures such as nanoparticles, nanotubes, nanowires, nanoribbons and nanosheets have been developed for potential applications as energy harvesters, tunable sensors, functional transducers and low-power actuators. In this study, lead-free BaTiO 3 nanorod bundle arrays (NBA) with highly piezoelectric properties were successfully synthesized on fluorine-doped tin oxide (FTO) substrate via a two-step process consisting of TiO2 epitaxial growth and BaTiO3 conversion. Through the TiO2 epitaxial growth on FTO substrate, (001) oriented TiO2 nanostructures formed vertically-aligned NBA with a bundle diameter of 80 nm and an aspect ratio of six. In particular, chemical etching of the TiO2 NBA was conducted to enlarge the surface area for effective Ba2+ ion diffusion during the perovskite conversion process from TiO2 to BaTiO3. The final structure of perovskite BaTiO3 NBA was found to exhibit a feasible piezoelectric response of 3.56 nm with a clear phase change of 180° from the single BaTiO3 bundle, by point piezoelectric forced microscopy (PFM) analysis. Consequently, highly piezoelectric NBA could be a promising nanostructure for various nanoscale electronic devices.

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.

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.

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

Al2O3 doping of TiO2 electrodes and applications in dye-sensitized solar cells

International Nuclear Information System (INIS)

Eom, Tae Sung; Kim, Kyung Hwan; Bark, Chung Wung; Choi, Hyung Wook

2014-01-01

Dye-sensitized solar cells (DSSCs) have been intensively studied since their discovery in 1991. DSSCs have been extensively researched over the past decades as cheaper alternatives to silicon solar cells due to their high energy-conversion efficiency and their low production cost. However, some problems need to be solved in order to enhance the efficiency of DSSCs. In particular, the electron recombination that occurs due to the contact between the transparent conductive oxide (TCO) and a redox electrolyte is one of the main limiting factors of efficiency. In this work, we report for the first time the improvement of the photovoltaic characteristics of DSSCs by doping TiO 2 with Al 2 O 3 . DSSCs were constructed using composite particles of Al 2 O 3 -doped TiO 2 and TiO 2 nanoparticles. The DSSCs using Al 2 O 3 showed the maximum conversion efficiency of 6.29% due to effective electron transport. DSSCs based on Al 2 O 3 -doped TiO 2 films showed better photovoltaic performance than cells fabricated with only TiO 2 nanoparticles. This result is attributed to the prevention of electron recombination between electrons in the TiO 2 conduction band with holes in the dye or the electrolyte. There mechanism is suggested based on impedance results, which indicated improved electron transport at the TiO 2 /dye/electrolyte interface.

CO2 Plasma-Treated TiO2 Film as an Effective Electron Transport Layer for High-Performance Planar Perovskite Solar Cells.

Science.gov (United States)

Wang, Kang; Zhao, Wenjing; Liu, Jia; Niu, Jinzhi; Liu, Yucheng; Ren, Xiaodong; Feng, Jiangshan; Liu, Zhike; Sun, Jie; Wang, Dapeng; Liu, Shengzhong Frank

2017-10-04

Perovskite solar cells (PSCs) have received great attention because of their excellent photovoltaic properties especially for the comparable efficiency to silicon solar cells. The electron transport layer (ETL) is regarded as a crucial medium in transporting electrons and blocking holes for PSCs. In this study, CO 2 plasma generated by plasma-enhanced chemical vapor deposition (PECVD) was introduced to modify the TiO 2 ETL. The results indicated that the CO 2 plasma-treated compact TiO 2 layer exhibited better surface hydrophilicity, higher conductivity, and lower bulk defect state density in comparison with the pristine TiO 2 film. The quality of the stoichiometric TiO 2 structure was improved, and the concentration of oxygen-deficiency-induced defect sites was reduced significantly after CO 2 plasma treatment for 90 s. The PSCs with the TiO 2 film treated by CO 2 plasma for 90 s exhibited simultaneously improved short-circuit current (J SC ) and fill factor. As a result, the PSC-based TiO 2 ETL with CO 2 plasma treatment affords a power conversion efficiency of 15.39%, outperforming that based on pristine TiO 2 (13.54%). These results indicate that the plasma treatment by the PECVD method is an effective approach to modify the ETL for high-performance planar PSCs.

Development of high efficient visible light-driven N, S-codoped TiO2 nanowires photocatalysts

Science.gov (United States)

Zhang, Yanlin; Liu, Peihong; Wu, Honghai

2015-02-01

One-dimensional (1D) nanowire material (especially nonmetal doped 1D nanowires) synthesized by a facile way is of great significance and greatly desired as it has higher charge carrier mobility and lower carrier recombination rate. N, S-codoped TiO2 nanowires were synthesized using titanium sulfate as a precursor and isopropanol as a protective capping agent by a hydrothermal route. The obtained doped nanowires were characterized by XRD, SEM, HRTEM, SAED, XPS, BET and UV-vis absorption spectrum. The incorporation of N and S into TiO2 NWs can lead to the expansion of its lattice and remarkably lower its electron-transfer resistance. Photocatalytic activity measurement showed that the N, S-codoped TiO2 nanowires with high quantum efficiency revealed the best photocatalytic performance for atrazine degradation under visible light irradiation compared to N, S-codoped TiO2 nanoparticles and S-doped TiO2 nanowires, which was attributed to (i) the synergistic effect of N and S doping in narrowing the band gap, separating electron-hole pairs and increasing the photoinduced electrons, and (ii) extending the anatase-to-rutile transformation temperature above 600 °C.

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

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.

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.

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

International Nuclear Information System (INIS)

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

2017-01-01

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

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-.

Preparation of flexible TiO2 photoelectrodes for dye-sensitized solar cells

Science.gov (United States)

Li, Wen-Ren; Wang, Hsiu-Hsuan; Lin, Chia-Feng; Su, Chaochin

2014-09-01

Dye-sensitized solar cells (DSSCs) based on nanocrystalline TiO2 photoelectrodes on indium tin oxide (ITO) coated polymer substrates have drawn great attention due to its lightweight, flexibility and advantages in commercial applications. However, the thermal instability of polymer substrates limits the process temperature to below 150 °C. In order to assure high and firm interparticle connection between TiO2 nanocrystals (TiO2-NC) and polymer substrates, the post-treatment of flexible TiO2 photoelectrodes (F-TiO2-PE) by mechanical compression was employed. In this work, Degussa P25 TiO2-NC was mixed with tert-butyl alcohol and DI-water to form TiO2 paste. F-TiO2-PE was then prepared by coating the TiO2 paste onto ITO coated polyethylene terephthalate (PET) substrate using doctor blade followed by low temperature sintering at 120 °C for 2 hours. To study the effect of mechanical compression, we applied 50 and 100 kg/cm2 pressure on TiO2/PET to complete the fabrication of F-TiO2-PE. The surface morphology of F-TiO2-PE was characterized using scanning electron microscopy. The resultant F-TiO2-PE sample exhibited a smooth, crack-free structure indicating the great improvement in the interparticle connection of TiO2-NC. Increase of compression pressure could lead to the increase of DSSC photoconversion efficiency. The best photoconversion efficiency of 4.19 % (open circuit voltage (Voc) = 0.79 V, short-circuit photocurrent density (Jsc) = 7.75 mA/cm2, fill factor (FF) = 0.68) was obtained for the F-TiO2-PE device, which showed great enhancement compared with the F-TiO2-PE cell without compression treatment. The effect of compression in DSSC performance was vindicated by the electrochemical impedance spectroscopy measurement.

The Effect of TiO2 Doped Photocatalytic Nano-Additives on the Hydration and Microstructure of Portland and High Alumina Cements

Directory of Open Access Journals (Sweden)

María Pérez-Nicolás

2017-10-01

Full Text Available Mortars with two different binders (Portland cement (PC and high alumina cement (HAC were modified upon the bulk incorporation of nano-structured photocatalytic additives (bare TiO2, and TiO2 doped with either iron (Fe-TiO2 or vanadium (V-TiO2. Plastic and hardened state properties of these mortars were assessed in order to study the influence of these nano-additives. Water demand was increased, slightly by bare TiO2 and Fe-TiO2, and strongly by V-TiO2, in agreement with the reduction of the particle size and the tendency to agglomerate. Isothermal calorimetry showed that hydration of the cementitious matrices was accelerated due to additional nucleation sites offered by the nano-additives. TiO2 and doped TiO2 did not show pozzolanic reactivity in the binding systems. Changes in the pore size distribution, mainly the filler effect of the nano-additives, accounted for the increase in compressive strengths measured for HAC mortars. A complex microstructure was seen in calcium aluminate cement mortars, strongly dependent on the curing conditions. Fe-TiO2 was found to be homogeneously distributed whereas the tendency of V-TiO2 to agglomerate was evidenced by elemental distribution maps. Water absorption capacity was not affected by the nano-additive incorporation in HAC mortars, which is a favourable feature for the application of these mortars.

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.

Thermodynamic investigation of the phase equilibrium boundary between TiO2 rutile and its α-PbO2-type high-pressure polymorph

Science.gov (United States)

Kojitani, Hiroshi; Yamazaki, Monami; Kojima, Meiko; Inaguma, Yoshiyuki; Mori, Daisuke; Akaogi, Masaki

2018-06-01

Heat capacity (C P) of rutile and α-PbO2 type TiO2 (TiO2-II) were measured by the differential scanning calorimetry and thermal relaxation method. Using the results, standard entropies at 1 atm and 298.15 K of rutile and TiO2-II were determined to be 50.04(4) and 46.54(2) J/mol K, respectively. Furthermore, thermal expansivity (α) determined by high-temperature X-ray diffraction measurement and mode Grüneisen parameters obtained by high-pressure Raman spectroscopy suggested the thermal Grüneisen parameter (γ th) for TiO2-II of 1.7(1). By applying the obtained low-temperature C P and γ th, the measured C P and α data of TiO2-II were extrapolated to higher temperature region using a lattice vibrational model calculation, as well as rutile. Internally consistent thermodynamic data sets of both rutile and TiO2-II assessed in this study were used to thermodynamically calculate the rutile‒TiO2-II phase equilibrium boundary. The most plausible boundary was obtained to be P (GPa) = 0.0074T (K) - 1.7. Our boundary suggests that the crystal growth of TiO2-II observed below 5.5 GPa and 900 K in previous studies advanced in its stability field. The phase boundary calculation also suggested small, exothermic phase transition enthalpy from rutile to TiO2-II at 1 atm and 298.15 K of - 0.5 to - 1.1 kJ/mol. This implies that the thermodynamic stability of rutile at 1 atm above room temperature is due to larger contribution of entropy term.

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.

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

Low-cost fabrication of highly sensitive room temperature hydrogen sensor based on ordered mesoporous Co-doped TiO2 structure

Science.gov (United States)

Li, Zhong; Haidry, Azhar Ali; Wang, Tao; Yao, Zheng Jun

2017-07-01

The development of cost-effective gas sensors with improved sensing properties and minimum power consumption for room temperature hydrogen leakage monitoring is in increasing demand. In this context, this report focus on the facile fabrication of ordered mesoporous TiO2 via evaporation-induced self-assembly route. With the controlled doping threshold (3%Co-TiO2), the output resistance change to 1000 ppm H2 is ˜4.1 × 103 with the response time of 66 s. The sensor response exhibits power law dependence with an increase in the hydrogen concentration, where the power law coefficient was found not only specific to the kind of target gas but also related to temperature. Further, the effect of structure integrity with doping level and humidity on sensing characteristics is interpreted in terms of variation in surface potential eVS and depletion region w caused by the adsorption of molecular oxygen O2-.

TiO_2 hierarchical hollow microspheres with different size for application as anodes in high-performance lithium storage

International Nuclear Information System (INIS)

Wang, Xiaobing; Meng, Qiuxia; Wang, Yuanyuan; Liang, Huijun; Bai, Zhengyu; Wang, Kui; Lou, Xiangdong; Cai, Bibo; Yang, Lin

2016-01-01

Graphical abstract: In the application of lithium-ion batteries, the influences of microsphere sizes are more significant than the secondary nanoparticles size and crystallinity of TiO_2-HSs for their transfer resistance and cycling performance, so that the bigger sizes of TiO_2-HSs can retain high reversible capacities after 30 recycles. - Highlights: • Hierarchical hollow microspheres have size-effect in the application of lithium ion battery. • The microsphere sizes can significantly affect the cycling capacities of TiO_2. • The nanoparticles size affect the initial discharge capacity and lithium ion diffusion. • Controlled microsphere size is more significant for improving TiO_2 cycling capacities. - Abstract: Nowadays, the safety issue has greatly hindered the development of large capacity lithium-ion batteries (LIBs), especially in electric vehicles applications. TiO_2 is a kind of potential anode candidate for improving the safety of LIBs. However, it still needs to understand how to improve the performance of TiO_2 anode in the practical applications. Herein, we design a contrast experiment by using three sizes of TiO_2 hierarchical hollow microspheres (TiO_2-HSs). The research results indicated that the cycling performance of TiO_2-HSs anode can be affected by the size of microspheres, and the nanoparticles size of microspheres and crystallinity of TiO_2 can affect their initial discharge capacity and lithium ion diffusion. And, the influence of microspheres size is more significant. This may provide a new strategy for improving the lithium-ion storage property of TiO_2 anode material in the practical applications.

Synergic effect of the TiO2-CeO2 nanoconjugate system on the band-gap for visible light photocatalysis

International Nuclear Information System (INIS)

Contreras-García, M.E.; García-Benjume, M. Lorena; Macías-Andrés, Víctor I.; Barajas-Ledesma, E.; Medina-Flores, A.; Espitia-Cabrera, M.I.

2014-01-01

Graphical abstract: - Highlights: • Nanostructured TiO 2 -CeO 2 films are successfully synthesized by combining of sputtering and electrophoresis methods. • Synergic effect of CeO 2 on TiO 2 band gap was demonstrated, CeO 2 diminishes it from 3.125 to 2.74. • Morphologic characterization of the nanoconjugate TiO 2 -CeO 2 films by different microscopy techniques. - Abstract: The TiO 2 -CeO 2 photocatalytic system in films is proposed here, in order to obtain photocatalytic systems that can be excited by solar light. The films were obtained through the electrophoretic deposition (EPD) of TiO 2 -CeO 2 gel on sputtered Ti Corning glass substrates. The synergic effect of CeO 2 in TiO 2 films was analyzed as a function of the optical band gap reduction at different concentrations (1, 5, 10, and 15 mol%). The effect of two thermal treatments was also evaluated. The lowest band gap value was obtained for the sample with 5 mol% ceria that was thermally treated at 700 °C. The nanostructured films were characterized by Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high angle annular dark field (HAADF), high resolution transmission electron microscopy (HRTEM), and atomic force microscopy (AFM). The nanocomposites were formed by TiO 2 and CeO 2 nanoparticles in the anatase and fluorite type phases, respectively

Synthesis of TiO2 nanorod-decorated graphene sheets and their highly efficient photocatalytic activities under visible-light irradiation

International Nuclear Information System (INIS)

Lee, Eunwoo; Hong, Jin-Yong; Kang, Haeyoung; Jang, Jyongsik

2012-01-01

Highlights: ► TiO 2 nanorods were successfully decorated on the surface of graphene sheets. ► Population of TiO 2 nanorods can be controlled by changing experimental conditions. ► TiO 2 nanorod-decorated graphene sheets have an expanded light absorption range. ► TiO 2 nanorod-decorated graphene sheets showed unprecedented photocatalytic activity. - Abstract: The titanium dioxide (TiO 2 ) nanorod-decorated graphene sheets photocatalysts with different TiO 2 nanorods population have been synthesized by a simple non-hydrolytic sol–gel approach. Electron microscopy and X-ray diffraction analysis indicated that the TiO 2 nanorods are well-dispersed and successfully anchored on the graphene sheet surface through the formation of covalent bonds between Ti and C atoms. The photocatalytic activities are evaluated in terms of the efficiencies of photodecomposition and adsorption of methylene blue (MB) in aqueous solution under visible-light irradiation. The as-synthesized TiO 2 nanorod-decorated graphene sheets showed unprecedented photodecomposition efficiency compared to the pristine TiO 2 nanorods and the commercial TiO 2 (P-25, Degussa) under visible-light. It is believed that this predominant photocatalytic activity is due to the synergistic contribution of both a retarded charge recombination rate caused by a high electronic mobility of graphene and an increased surface area originated from nanometer-sized TiO 2 nanorods. Furthermore, photoelectrochemical study is performed to give deep insights into the primary roles of graphene that determines the photocatalytic activity.

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)

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...

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.

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%.

Decolorization of Methylene Blue with TiO2 Sol via UV Irradiation Photocatalytic Degradation

Directory of Open Access Journals (Sweden)

Jun Yao

2010-01-01

Full Text Available TiO2 sol was prepared for the degradation of methylene blue (MB solution under ultraviolet (UV irradiation. The absorption spectra of MB indicated that the maximum wavelength, 663 nm, almost kept the same. The performance of 92.3% for color removal was reached after 160 min. The particle size of TiO2 sol was about 22.5 nm. X-ray diffraction showed that TiO2 consisted of a single anatase phase. The small size and anatase phase probably resulted in high photocatalytic activity of TiO2 sol. The degradation ratio decreased as the initial concentration of MB increased. The photodegradation efficiency decreased in the order of pH 2>pH 9>pH 7. Regarding catalyst load, the degradation increased with the mass of catalyst up to an amount of 1.5 g⋅L−1 then decreased as the mass continued to increase. The addition of H2O2 to TiO2 sol resulted in an increase on the degradation ratio.

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.

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.

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.

Highly photocatalytic TiO_2 interconnected porous powder fabricated by sponge-templated atomic layer deposition

International Nuclear Information System (INIS)

Pan, Shengqiang; Zhao, Yuting; Huang, Gaoshan; Li, Menglin; Mei, Yongfeng; Wang, Jiao; Zheng, Lirong; Baunack, Stefan; Schmidt, Oliver G; Gemming, Thomas

2015-01-01

A titanium dioxide (TiO_2) interconnected porous structure has been fabricated by means of atomic layer deposition of TiO_2 onto a reticular sponge template. The obtained freestanding TiO_2 with large surface area can be easily taken out of the water to solve a complex separation procedure. A compact and conformal nanocoating was evidenced by morphologic characterization. A phase transition, as well as production of oxygen vacancies with increasing annealing temperature, was detected by x-ray diffraction and x-ray photoelectron spectroscopy, respectively. The photocatalytic experimental results demonstrated that the powder with appropriate annealing treatment possessed excellent photocatalytic ability due to the co-action of high surface area, oxygen vacancies and the optimal crystal structure. (paper)

Photocatalyzed degradation of flumequine by doped TiO2 and simulated solar light

International Nuclear Information System (INIS)

Nieto, J.; Freer, J.; Contreras, D.; Candal, R.J.; Sileo, E.E.; Mansilla, H.D.

2008-01-01

Titanium dioxide was obtained in its pure form (TiO 2 ) and in the presence of urea (u-TiO 2 ) and thiourea (t-TiO 2 ) using the sol-gel technique. The obtained powders were characterized by BET surface area analysis, Infrared Spectroscopy, Diffuse Reflectance Spectroscopy and the Rietveld refinement of XRD measurements. All the prepared catalysts show high anatase content (>99%). The a and b-cell parameters of anatase increase in the order TiO 2 2 2 , while the c-parameter presents the opposite trend. Because of the interplay in cell dimensions, the cell grows thicker and shorter when prepared in the presence of urea and thiourea, respectively. The cell volume decreases in the order t-TiO 2 > u-TiO 2 > TiO 2 . The photocatalytic activities of the samples were determined on flumequine under solar-simulated irradiation. The most active catalysts were u-TiO 2 and t-TiO 2 , reaching values over 90% of flumequine degradation after 15 min irradiation, compared with values of 55% for the pure TiO 2 catalyst. Changing simultaneously the catalyst amount (t-TiO 2 ) and pH, multivariate analysis using the response surface methodology was used to determine the roughly optimal conditions for flumequine degradation. The optimized conditions found were pH below 7 and a catalyst amount of 1.6 g L -1

CNTs threaded (001) exposed TiO2 with high activity in photocatalytic NO oxidation.

Science.gov (United States)

Xiao, Shuning; Zhu, Wei; Liu, Peijue; Liu, Fanfan; Dai, Wenrui; Zhang, Dieqing; Chen, Wei; Li, Hexing

2016-02-07

A microwave-ionothermal strategy was developed for in situ synthesis of CNTs threaded TiO2 single crystal with a tunable percentage of surface exposed (001) active facets. The CNTs were used as microwave antennas to create local "super hot" dots to induce Ti(3+) adsorption and hydrolysis, thereby leading to a good assembly of (001) facets exposed single crystalline TiO2 threaded by the CNTs in the presence of Hmim[BF4] ionic liquid. Due to the high percentage of the active (001) facets of single crystal TiO2 and the direct electron transfer property of the CNTs, the as-prepared CNTs-TiO2 composite showed a photocatalytic NO removal ratio of up to 76.8% under UV irradiation. In addition, with self-doped Ti(3+), the CNTs-TiO2 composite also exhibited an enhanced activity under irradiation with either solar lights or visible lights, showing good potential in practical applications for environmental remediation.

Azo dyes degradation using TiO2-Pt/graphene oxide and TiO2-Pt/reduced graphene oxide photocatalysts under UV and natural sunlight irradiation

Science.gov (United States)

Rosu, Marcela-Corina; Coros, Maria; Pogacean, Florina; Magerusan, Lidia; Socaci, Crina; Turza, Alexandru; Pruneanu, Stela

2017-08-01

The photocatalytic degradation of azo dyes with different structures (amaranth, sunset yellow and tartrazine) using TiO2-Pt nanoparticles (TPt), TiO2-Pt/graphene oxide (TPt-GO) and TiO2-Pt/reduced graphene oxide (TPt-rGO) composites were investigated in the presence of UV and natural sunlight irradiation. The composites were prepared by a combined chemical-thermal method and characterized by Transmission Electron Microscopy (TEM), X-ray powder diffraction (XRD), Infrared (FTIR) and UV-Vis spectroscopy. The modification of TiO2-Pt with graphene oxide shifted its optical absorption edge towards the visible region and increased its photocatalytic activity under UV and natural sunlight irradiation. The efficiency of catalysts on azo dyes degradation (in similar conditions) reached high values (above 99%) under sunlight conditions, proving the remarkable photocatalytic activities of obtained composites. TPt-GO nanocomposite exhibited higher photoactivity than TPt or TPt-rGO, demonstrating degradation efficiencies of 99.56% for amaranth, 99.15% for sunset yellow and 96.23% for tartrazine. The dye photodegradation process follows a pseudo-first-order kinetic with respect to the Langmuir-Hinshelwood reaction mechanism. A direct dependence between azo dyes degradation rate and chemical structure of dyes has been observed.

Sol-Gel TiO2 thin films sensitized with the mulberry pigment cyanidin

Directory of Open Access Journals (Sweden)

Emerson Henrique de Faria

2007-12-01

Full Text Available TiO2 films have various applications, among them solar cells and photodegradation of pollutants. In this study, we investigated TiO2 films functionalized with the organic dye cyanidin extracted from black mulberry (Morus nigra. The TiO2 was functionalized by the sol-gel method and the film was deposited on glass substrates by dip-coating. Our aim was to investigate the interaction between the semiconductor and the dye, as well as the influence of the velocity and number of deposits on the characteristics of the film. Using ultraviolet-visible spectroscopy, we observed a shift from the maximum absorption band at 545 nm for the dye’s ethanol solution to 595 nm for the film, indicating interaction of the cyanidin with the TiO2. The absorption spectra in the infrared region of the functionalized TiO2 particles showed bands characteristic of the oxide and indicated their interaction with the dye. Using profilometry and m-line techniques, we found that the films presented thicknesses in the order of 100 nm. A SEM analysis confirmed the high density of the films.

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.

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).

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

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.

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.

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

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.

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.

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

DEFF Research Database (Denmark)

Su, Ren; Bechstein, Ralf; Kibsgaard, Jakob

2012-01-01

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

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.

INKJET PRINTING OF HIGH REFRACTIVE STRUCTURES BASED ON TiO2 SOL

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Elena A. Eremeeva

2016-11-01

Full Text Available Subject of Research. The paper deals with description of novel inkjet printing method for optical elements formed by structures based on TiO2 sol. The proposed approach presents effective way to obtain such optical nano objects as diffraction structures and transparent interference patterns. Methods. TiO2 nanoparticles were synthesized by hydrolysis of titanium isopropoxide (0.36 mol in deionized water (33.3 mol under vigorous stirring and using nitric acid (0.04 mol as a protonating agent. Viscosity was determined by Brookfield HA/HB viscometer, and surface tension - by Kyowa DY-700 tensiometer. Titanium dioxide inks were deposited on commercially available microembossed PET film with a thickness of 20 µm. To print titania ink Canon Pixma IP 2840 desktop office printer was used with a drop volume of 2 pL. The thickness of an inkjet TiO2 layer after drying in the air and removal of the solvents did not exceed 500 nm with a refractive index not less than 2.08 in the entire visible range.Main Results. The synthesis of aqueous TiO2 sol was used to obtain the ink with desirable rheological characteristics: viscosity and surface tension. The required rheology was regulated by controlling parameters of sol-gel transition in the system of aqueous titanium dioxide sol and by adding ethanol that affects the charge of double electrical layer of disperse phase. The reviled ratio of titanium dioxide sol and ethanol in the system gives such values of viscosity and surface tension that make this material convenient for inkjet printing. The coatings created by sol have a high refractive index in the entire visible range (not less than 2.08. We have shown that the deposition of optical transparent microstructures with diffraction effect has an ability to be applied on the transparent surfaces. The morphology of particles and the topology of printed structures were analyzed by optic and atomic-force microscopes.Practical Relevance. We have proposed the approach

MIL-125-NH2@TiO2 Core-Shell Particles Produced by a Post-Solvothermal Route for High-Performance Photocatalytic H2 Production.

Science.gov (United States)

Zhang, Bingxing; Zhang, Jianling; Tan, Xiuniang; Shao, Dan; Shi, Jinbiao; Zheng, Lirong; Zhang, Jing; Yang, Guanying; Han, Buxing

2018-05-02

Metal-organic frameworks (MOFs) have proven to be an interesting class of sacrificial precursors of functional inorganic materials for catalysis, energy storage, and conversion applications. However, the controlled synthesis of MOF-derived materials with desirable compositions, structures, and properties still remains a big challenge. Herein, we propose a post-solvothermal route for the outer-to-inner loss of organic linkers from MOF, which is simple, rapid, and controllable and can be operated at temperature much lower than that of the commonly adopted pyrolysis method. By such a strategy, the MIL-125-NH 2 particles coated by TiO 2 nanosheets were produced, and the thickness of TiO 2 shell can be easily tuned. The MIL-125-NH 2 @TiO 2 core-shell particles combine the advantages of highly active TiO 2 nanosheets, MIL-125-NH 2 photosensitizer, plenty of linker defects and oxygen vacancies, and mesoporous structure, which allows them to be utilized as photocatalysts for the visible-light-driven hydrogen production reaction. It is remarkable that the hydrogen evolution rate by MIL-125-NH 2 @TiO 2 can be enhanced 70 times compared with the pristine MIL-125-NH 2 . Such a route can be easily applied to the synthesis of different kinds of MOF-derived functional materials.

Fabrication and characterization of 6Li-enriched Li2TiO3 pebbles for a high Li-burnup irradiation test

International Nuclear Information System (INIS)

Tsuchiya, Kunihiko; Kawamura, Hiroshi

2006-10-01

Lithium titanate (Li 2 TiO 3 ) pebbles are considered to be a candidate material of tritium breeders for fusion reactor from viewpoints of easy tritium release at low temperatures (about 300degC) and chemical stability. In the present study, trial fabrication tests of 6 Li-enriched Li 2 TiO 3 pebbles of 1mm in diameter were carried out by a wet process with a dehydration reaction, and characteristics of the 6 Li-enriched Li 2 TiO 3 pebbles were evaluated for preparation of a high Li-burnup test in a testing reactor. Powder of 96at% 6 Li-enriched Li 2 TiO 3 was prepared by a solid state reaction, and two kinds of 6 Li-enriched Li 2 TiO 3 pebbles, namely un-doped and TiO 2 -doped Li 2 TiO 3 pebbles, were fabricated by the wet process. Based on results of the pebble fabrication tests, two kinds of 6 Li-enriched Li 2 TiO 3 pebbles were successfully fabricated with target values (density: 80-85%T.D., grain size: 2 TiO 3 pebbles was a satisfying value of about 1.05. Contact strength of these pebbles was about 6300MPa, which was almost the same as that of the Li 2 TiO 3 pebbles with natural Li. (author)

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...

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.

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%

Growth and characterization of epitaxial anatase TiO2(001) on SrTiO3-buffered Si(001) using atomic layer deposition

International Nuclear Information System (INIS)

McDaniel, M.D.; Posadas, A.; Wang, T.; Demkov, A.A.; Ekerdt, J.G.

2012-01-01

Epitaxial anatase titanium dioxide (TiO 2 ) films have been grown by atomic layer deposition (ALD) on Si(001) substrates using a strontium titanate (STO) buffer layer grown by molecular beam epitaxy (MBE) to serve as a surface template. The growth of TiO 2 was achieved using titanium isopropoxide and water as the co-reactants at a substrate temperature of 225–250 °C. To preserve the quality of the MBE-grown STO, the samples were transferred in-situ from the MBE chamber to the ALD chamber. After ALD growth, the samples were annealed in-situ at 600 °C in vacuum (10 −7 Pa) for 1–2 h. Reflection high-energy electron diffraction was performed during the MBE growth of STO on Si(001), as well as after deposition of TiO 2 by ALD. The ALD films were shown to be highly ordered with the substrate. At least four unit cells of STO must be present to create a stable template on the Si(001) substrate for epitaxial anatase TiO 2 growth. X-ray diffraction revealed that the TiO 2 films were anatase with only the (004) reflection present at 2θ = 38.2°, indicating that the c-axis is slightly reduced from that of anatase powder (2θ = 37.9°). Anatase TiO 2 films up to 100 nm thick have been grown that remain highly ordered in the (001) direction on STO-buffered Si(001) substrates. - Highlights: ► Epitaxial anatase films are grown by atomic layer deposition (ALD) on Si(001). ► Four unit cells of SrTiO 3 on silicon create a stable template for ALD. ► TiO 2 thin films have a compressed c-axis and an expanded a-axis. ► Up to 100 nm thick TiO 2 films remain highly ordered in the (001) direction.

Fabrication and Characteristics of Macroporous TiO2 Photocatalyst

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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.

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

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.

Electron Beam Evaporated TiO2 Layer for High Efficiency Planar Perovskite Solar Cells on Flexible Polyethylene Terephthalate Substrates

KAUST Repository

Qiu, Weiming; Paetzold, Ulrich W; Gehlhaar, Robert; Smirnov, Vladimir; Boyen, Hans-Gerd; Tait, Jeffrey Gerhart; Conings, Bert; Zhang, Weimin; Nielsen, Christian; McCulloch, Iain; Froyen, Ludo; Heremans, Paul; Cheyns, David

2015-01-01

The TiO2 layer made by electron beam (e-beam) induced evaporation is demonstrated as electron transport layer (ETL) in high efficiency planar junction perovskite solar cells. The temperature of the substrate and the thickness of the TiO2 layer can

Structural and electrical characteristics of high-κ Er2O3 and Er2TiO5 gate dielectrics for a-IGZO thin-film transistors.

Science.gov (United States)

Chen, Fa-Hsyang; Her, Jim-Long; Shao, Yu-Hsuan; Matsuda, Yasuhiro H; Pan, Tung-Ming

2013-01-08

In this letter, we investigated the structural and electrical characteristics of high-κ Er2O3 and Er2TiO5 gate dielectrics on the amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistor (TFT) devices. Compared with the Er2O3 dielectric, the a-IGZO TFT device incorporating an Er2TiO5 gate dielectric exhibited a low threshold voltage of 0.39 V, a high field-effect mobility of 8.8 cm2/Vs, a small subthreshold swing of 143 mV/decade, and a high Ion/Ioff current ratio of 4.23 × 107, presumably because of the reduction in the oxygen vacancies and the formation of the smooth surface roughness as a result of the incorporation of Ti into the Er2TiO5 film. Furthermore, the reliability of voltage stress can be improved using an Er2TiO5 gate dielectric.

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

International Nuclear Information System (INIS)

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

2015-01-01

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

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

Science.gov (United States)

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

2014-12-01

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

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

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.

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

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Kai Liu

2015-01-01

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

Highly-ordered mesoporous titania thin films prepared via surfactant assembly on conductive indium-tin-oxide/glass substrate and its optical properties

International Nuclear Information System (INIS)

Uchida, Hiroshi; Patel, Mehul N.; May, R. Alan; Gupta, Gaurav; Stevenson, Keith J.; Johnston, Keith P.

2010-01-01

Highly ordered mesoporous titanium dioxide (titania, TiO 2 ) thin films on indium-tin-oxide (ITO) coated glass were prepared via a Pluronic (P123) block copolymer template and a hydrophilic TiO 2 buffer layer. The contraction of the 3D hexagonal array of P123 micelles upon calcination merges the titania domains on the TiO 2 buffer layer to form mesoporous films with a mesochannel diameter of approximately 10 nm and a pore-to-pore distance of 10 nm. The mesoporous titania films on TiO 2 -buffered ITO/glass featured an inverse mesospace with a hexagonally-ordered structure, whereas the films formed without a TiO 2 buffer layer had a disordered microstructure with submicron cracks because of non-uniform water condensation on the hydrophobic ITO/glass surface. The density of the mesoporous film was 83% that of a bulk TiO 2 film. The optical band gap of the mesoporous titania thin film was approximately 3.4 eV, larger than that for nonporous anatase TiO 2 (∼ 3.2 eV), suggesting that the nanoscopic grain size leads to an increase in the band gap due to weak quantum confinement effects. The ability to form highly-ordered mesoporous titania films on electrically conductive and transparent substrates offers the potential for facile fabrication of high surface area semiconductive films with small diffusion lengths for optoelectronics applications.

Electron Beam Evaporated TiO2 Layer for High Efficiency Planar Perovskite Solar Cells on Flexible Polyethylene Terephthalate Substrates

KAUST Repository

Qiu, Weiming

2015-09-30

The TiO2 layer made by electron beam (e-beam) induced evaporation is demonstrated as electron transport layer (ETL) in high efficiency planar junction perovskite solar cells. The temperature of the substrate and the thickness of the TiO2 layer can be easily controlled with this e-beam induced evaporation method, which enables the usage of different types of substrates. Here, Perovskite solar cells based on CH3NH3PbI3-xClx achieve power conversion efficiencies of 14.6% on glass and 13.5% on flexible plastic substrates. The relationship between the TiO2 layer thickness and the perovskite morphology is studied with scanning electron microscope (SEM), atomic force microscope (AFM), and X-ray photoelectron spectroscopy (XPS). Our results indicate that pinholes in thin TiO2 layer lead to pinholes in the perovskite layer. By optimizing the TiO2 thickness, perovskite layers with substantially increased surface coverage and reduced pinhole areas are fabricated, increasing overall device performance.

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

KAUST Repository

Isimjan, Tayirjan T.

2014-12-19

Highly ordered nitrogen-doped titanium dioxide (N-doped TiO2) nanotube array films with enhanced photo-electrochemical water splitting efficiency (PCE) for hydrogen generation were fabricated by electrochemical anodization, followed by annealing in a nitrogen atmosphere. Morphology, structure and composition of the N-doped TiO2 nanotube array films were investigated by FE-SEM, XPS, UV-Vis and XRD. The effect of annealing temperature, heating rate and annealing time on the morphology, structure, and photo-electrochemical property of the N-doped TiO2 nanotube array films were investigated. A design of experiments method was applied in order to minimize the number of experiments and obtain a statistical model for this system. From the modelling results, optimum values for the influential factors were obtained in order to achieve the maximum PCE. The optimized experiment resulted in 7.42 % PCE which was within 95 % confidence interval of the predicted value by the model. © 2014 Springer Science+Business Media.

Data on the effect of improved TiO2/FTO interface and Ni(OH2 cocatalyst on the photoelectrochemical performances and stability of CdS cased ZnIn2S4/TiO2 heterojunction

Directory of Open Access Journals (Sweden)

Mahadeo A. Mahadik

2018-04-01

Full Text Available This data article presents the experimental evidences of the effect of TiO2-fluorine doped tin oxide interface annealing and Ni(OH2 cocatalysts on the photoelectrochemical, structural, morphological and optical properties of Ni(OH2/CdS/ZnIn2S4/TiO2 heterojunction. The Raman spectroscopy exhibits the sharp features of the rutile phase of TiO2 and in agreement with the X-ray diffraction data. The band gap energy of the 500 °C sample was found to be 3.12 eV, further it was increased to 3.20, 3.22 eV for samples annealed at 600 and 700 °C respectively. The decrease in the band gap energy at 500 °C related to the oxygen vacancies and was analysed by photoluminescence spectroscopy analysis. The synthesis, characterization methods and other experimental details of TiO2 based heterostructure are also provided. The presence of CdS and ZnIn2S4 coating on surface of TiO2 electrodes providing a high surface area, extended visible absorption and helps to improve the change separation. This data article contains data related to the research article entitled “Highly efficient and stable 3D Ni(OH2/CdS/ZnIn2S4/TiO2 heterojunction under solar light: Effect of an improved TiO2/FTO interface and cocatalyst” (Mahadik et al., 2017 [1]. Keywords: Annealed TiO2 nanorods, CdS/ZnIn2S4/TiO2 heterostructure, Ni(OH2 cocatalyst, TiO2-FTO interface

Design of H3PW12O40/TiO2 nano-photocatalyst for efficient photocatalysis under simulated sunlight irradiation

International Nuclear Information System (INIS)

Zhao, Kun; Lu, Ying; Lu, Nan; Zhao, Yahui; Yuan, Xing; Zhang, Hao; Teng, Lianghui; Li, Fu

2013-01-01

H 3 PW 12 O 40 /TiO 2 (PW 12 /TiO 2 ) nano-photocatalyst was successfully synthesized through a modified sol–gel-hydrothermal method. The X-ray diffraction (XRD) patterns, Fourier transform infrared (FT-IR) spectra, UV–vis diffuse reflectance spectrum (UV–vis DRS), and N 2 adsorption–desorption isotherms were characterized respectively to investigate the physical and chemical properties of prepared catalysts. Under simulated sunlight (320 nm 12 /TiO 2 . The results showed that the pollutants degradation followed first-order kinetics, and the kinetic constants of photocatalytic degradation of fuchsin acid, malachite green and PNP were 2.82, 4.66, and 3.48 times as great as that using pristine TiO 2 , respectively. The high pollutants degradation efficiency was ascribed to the synergistic effect between H 3 PW 12 O 40 and TiO 2 , which resulted in enhanced quantum efficiency and high light harvesting efficiency. We believe this work could provide new insights into the fabrication of photocatalyst with high photocatalytic performance and facilitate their practical application in environmental issues.

Enhanced visible light photocatalytic properties of Fe-doped TiO2 nanorod clusters and monodispersed nanoparticles

International Nuclear Information System (INIS)

Liu, Y.; Wei, J.H.; Xiong, R.; Pan, C.X.; Shi, J.

2011-01-01

In order to get photocatalysts with desired morphologies and enhanced visible light responses, the Fe-doped TiO 2 nanorod clusters and monodispersed nanoparticles were prepared by modified hydrothermal and solvothermal method, respectively. The microstructures and morphologies of TiO 2 crystals can be controlled by restraining the hydrolytic reaction rates. The Fe-doped photocatalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis absorption spectroscopy (UV-vis), N 2 adsorption-desorption measurement (BET), and photoluminescence spectroscopy (PL). The refinements of the microstructures and morphologies result in the enhancement of the specific surface areas. The Fe 3+ -dopants in TiO 2 lattices not only lead to the significantly extending of the optical responses from UV to visible region but also diminish the recombination rates of the electrons and holes. The photocatalytic activities were evaluated by photocatalytic decomposition of formaldehyde in air under visible light illumination. Compared with P25 (TiO 2 ) and N-doped TiO 2 nanoparticles, the Fe-doped photocatalysts show high photocatalytic activities under visible light.

Synthesis of TiO2/Bi2S3 heterojunction with a nuclear-shell structure and its high photocatalytic activity

International Nuclear Information System (INIS)

Lu, Juan; Han, Qiaofeng; Wang, Zuoshan

2012-01-01

Highlights: ► Bi 2 S 3 was doped into TiO 2 and it was clearly proved by the expander of the crystalline lattice in XRD result. ► As-prepared TiO 2 /Bi 2 S 3 heterojunctions have a nuclear-shell structure which has not been reported. ► As-prepared TiO 2 /Bi 2 S 3 heterojunctions have the excellent photocatalytic activity. -- Abstract: TiO 2 /Bi 2 S 3 heterojunctions with a nuclear-shell structure were prepared by the coprecipitation method. The products were characterized by X-ray diffraction analysis, Raman spectra, transmission electron microscope images and energy dispersion X-ray spectra. Results showed that as-prepared Bi 2 S 3 was urchin-like, made from many nanorods, and TiO 2 /Bi 2 S 3 heterojunctions have a similar nuclear-shell structure, with Bi 2 S 3 as the shell and TiO 2 as the nuclear. The photocatalytic experiments performed under UV irradiation using methyl orange as the pollutant revealed that the photocatalytic activity of TiO 2 could be improved by introduction of an appropriate amount of Bi 2 S 3 . However, excessive amount of Bi 2 S 3 would result in the decrease of photocatalytic activity of TiO 2 . The relative mechanism was proposed.

Comparative analysis of Dye-Sensitized Solar Cells (DSSC) having different nanocrystalline TiO2 layer structures

International Nuclear Information System (INIS)

Forcade, Fresnel; Gonzalez, Bernardo; Vigil, Elena; Jennings, James R.; Duna, Halina; Wang, Hongxia; Peter, Laurence M.

2009-01-01

Full text: Dye-sensitized solar cells (DSSC) are very prospective because of their low cost and comparatively not so low efficiency. This represents an advantage together with the innocuous character of the constituent materials. We study different types of DSSC. The procedure for making them has been the same except for the TiO 2 layer structure. This layer must be porous and nanocrystalline in order to increase light absorption by the sensitizer. On the other hand, this condition causes that the electrolyte contacts the transparent conducting oxide (TCO) underneath the TiO 2 originating undesired recombinations. Also the electrical contact of the Tio to the TCO depends on the technology used to deposit the TiO 2 . In order to avoid possible leakage currents caused by recombinations from the TCO to the electrolyte and improve TiO 2 -TCO electrical contact, a thin TiO 2 film is placed in between the porous TiO 2 layer and the TCO. Different structures are obtained using different technologies to obtain the thin TiO 2 film. These structures are analyzed from their volt-amperic characteristic, external quantum efficiency spectra and voltage decay observed when light is suppressed. Results obtained allow making recommendations regarding nanocrystalline TiO 2 structure to be used in DSSC. (author)

Highly Al-doped TiO2 nanoparticles produced by Ball Mill Method: structural and electronic characterization

International Nuclear Information System (INIS)

Santos, Desireé M. de los; Navas, Javier; Sánchez-Coronilla, Antonio; Alcántara, Rodrigo; Fernández-Lorenzo, Concha; Martín-Calleja, Joaquín

2015-01-01

Highlights: • Highly Al-doped TiO 2 nanoparticles were synthesized using a Ball Mill Method. • Al doping delayed anatase to rutile phase transformation. • Al doping allow controlling the structural and electronic properties of nanoparticles. - Abstract: This study presents an easy method for synthesizing highly doped TiO 2 nanoparticles. The Ball Mill method was used to synthesize pure and Al-doped titanium dioxide, with an atomic percentage up to 15.7 at.% Al/(Al + Ti). The samples were annealed at 773 K, 973 K and 1173 K, and characterized using ICP-AES, XRD, Raman spectroscopy, FT-IR, TG, STEM, XPS, and UV–vis spectroscopy. The effect of doping and the calcination temperature on the structure and properties of the nanoparticles were studied. The results show high levels of internal doping due to the substitution of Ti 4+ ions by Al 3+ in the TiO 2 lattice. Furthermore, anatase to rutile transformation occurs at higher temperatures when the percentage of doping increases. Therefore, Al doping allows us to control the structural and electronic properties of the nanoparticle synthesized. So, it is possible to obtain nanoparticles with anatase as predominant phase in a higher range of temperature

Characterization of new bioactive coatings of hydroxyapatite and TiO2 obtained by High-Velocity Oxy-Fuel

International Nuclear Information System (INIS)

Melero, H.; Fernandez, J.; Dosta, S.; Guilemany, J. M.

2011-01-01

Hydroxyapatite (Hap: Ca 1 0(PO 4 ) 6 OH 2 ) is a biocompatible and bioactive ceramic material widely used as a coating on metal surfaces (dental implants, hip replacements ...), but the low adhesion between Hap and the substrate, due to differences in thermal expansion coefficients of both (very important in thermal spraying because of the fast cooling of the coating, which can produce a lost of adherence), and the degradation of Hap, have been tried to be improved through the incorporation of TiO 2 to get a good combination of mechanical properties. Therefore, the objective of this project is to produce coatings of Hap 80% TiO 2 and 20% (by weight) on Ti6Al4V by High-Speed Thermal Spray (HVOF). The study of the microstructure has been carried out using scanning electron microscopy and characterization of the crystalline phases by X-ray diffraction and Raman spectrometry. The coatings adhesion has been measured by tensile tests according to ASTM C633-01 (2008), and their bioactivity also has been evaluated through its immersion in simulated body fluid (SBF), in order to measure their capacity to form an apatite layer on their surface. (Author) 26 refs.

Photodecomposition of volatile organic compounds using TiO2 nanoparticles.

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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.

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

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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.

Mesoporous anatase TiO2/reduced graphene oxide nanocomposites: A simple template-free synthesis and their high photocatalytic performance

International Nuclear Information System (INIS)

Zhou, Qi; Zhong, Yong-Hui; Chen, Xing; Huang, Xing-Jiu; Wu, Yu-Cheng

2014-01-01

Graphical abstract: - Highlights: • Mesoporous TiO 2 nanoparticles with anatase phase were assembled on reduced graphene oxide via a template-free one-step hydrothermal method. • The TiO 2 /rGO nanocomposites have better adsorption capacity and photocatalytic degradation efficiency for dyes removal. • Improved dye adsorption and photogenerated charge separation are responsible for enhanced activity. - Abstract: Mesoporous anatase phase TiO 2 was assembled on reduced graphene oxide (rGO) using a template-free one-step hydrothermal process. The nanocomposites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and Brunauer–Emmett–Teller (BET) surface area. Morphology of TiO 2 was related to the content of graphene oxide. TiO 2 /rGO nanocomposites exhibited excellent photocatalytic activity for the photo-degradation of methyl orange. The degradation rate was 4.5 times greater than that of pure TiO 2 nanoparticles. This difference was attributed to the thin two-dimensional graphene sheet. The graphene sheet had a large surface area, high adsorption capacity, and acted as a good electron acceptor for the transfer of photo-generated electrons from the conduction band of TiO 2 . The enhanced surface adsorption characteristics and excellent charge transport separation were independent properties of the photocatalytic degradation process

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

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

2016-12-01

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

Adsorption Equilibrium and Kinetics of Gardenia Blue on TiO2 Photoelectrode for Dye-Sensitized Solar Cells

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Tae-Young Kim

2014-01-01

Full Text Available Nanostructured porous TiO2 paste was deposited on the FTO conductive glass using squeeze printing technique in order to obtain a TiO2 thin film with a thickness of 10 μm and an area of 4 cm2. Gardenia blue (GB extracted from Gardenia jasminode Ellis was employed as the natural dye for a dye-sensitized solar cell (DSSC. Adsorption studies indicated that the maximum adsorption capacity of GB on the surface of TiO2 thin film was approximately 417 mg GB/g TiO2 photoelectrode. The commercial and natural dyes, N-719 and GB, respectively, were employed to measure the adsorption kinetic data, which were analyzed by pseudo-first-order and pseudo-second-order models. The energy conversion efficiency of the TiO2 electrode with successive adsorptions of GB dye was about 0.2%.

FTIR and Raman Characterization of TiO2 Nanoparticles Coated with Polyethylene Glycol as Carrier for 2-Methoxyestradiol

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Andrea León

2017-01-01

Full Text Available The aim of this study was to prepare a novel targeting drug delivery system for 2-Methoxyestradiol (2ME in order to improve the clinical application of this antitumor drug. It is based in nanoparticles (NPs of titanium dioxide (TiO2 coated with polyethylene glycol (PEG and loaded with 2ME. A complete IR and Raman characterization have been made to confirm the formation of TiO2–PEG–2ME composite. Vibrational modes have been assigned for TiO2, PEG, and 2ME and functionalized TiO2–PEG and TiO2–PEG–2ME. The observed variation in peak position of FTIR and Raman of each for these composites has been elucidated in terms of intermolecular interactions between PEG–2ME and TiO2, obtaining step-by-step the modification processes that were attributed to the conjugation of PEG and 2ME to TiO2 NPs. Modifying TiO2 NPs with PEG loaded with the 2ME drug revealed that the titanium dioxide nanocarrier possesses an effective adsorption capability, and we discuss their potential application as a system of drug delivery.

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

Disruption of Autolysis in Bacillus subtilis using TiO2 Nanoparticles.

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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.

Oriented epitaxial TiO2 nanowires for water splitting

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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.

TiO2-SnS2 nanocomposites: solar-active photocatalytic materials for water treatment.

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Kovacic, Marin; Kusic, Hrvoje; Fanetti, Mattia; Stangar, Urska Lavrencic; Valant, Matjaz; Dionysiou, Dionysios D; Bozic, Ana Loncaric

2017-08-01

The study is aimed at evaluating TiO 2 -SnS 2 composites as effective solar-active photocatalysts for water treatment. Two strategies for the preparation of TiO 2 -SnS 2 composites were examined: (i) in-situ chemical synthesis followed by immobilization on glass plates and (ii) binding of two components (TiO 2 and SnS 2 ) within the immobilization step. The as-prepared TiO 2 -SnS 2 composites and their sole components (TiO 2 or SnS 2 ) were inspected for composition, crystallinity, and morphology using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX) analyses. Diffuse reflectance spectroscopy (DRS) was used to determine band gaps of immobilized TiO 2 -SnS 2 and to establish the changes in comparison to respective sole components. The activity of immobilized TiO 2 -SnS 2 composites was tested for the removal of diclofenac (DCF) in aqueous solution under simulated solar irradiation and compared with that of single component photocatalysts. In situ chemical synthesis yielded materials of high crystallinity, while their morphology and composition strongly depended on synthesis conditions applied. TiO 2 -SnS 2 composites exhibited higher activity toward DCF removal and conversion in comparison to their sole components at acidic pH, while only in situ synthesized TiO 2 -SnS 2 composites showed higher activity at neutral pH.

The effect of Co-doping on the humidity sensing properties of ordered mesoporous TiO2

Science.gov (United States)

Li, Zhong; Haidry, Azhar Ali; Gao, Bin; Wang, Tao; Yao, ZhengJun

2017-08-01

Monitoring of humidity is of utmost importance as it is essential part of almost every process in our life. Many commercial humidity sensors based on metal oxide semiconductors are available in the market, but there is still need to synthesize low-cost, fast and highly sensitive humidity sensors with no interference from background environment. The aim of this work was to fabricate the ordered mesoporous un-doped and Co-doped TiO2 (0.1-5 mol% Co) and to analyze its humidity sensing properties at room temperatures. The ordered mesoporous powders with high specific surface area (SSA) were prepared by multicomponent self-assembly procedure and then spray-coated onto the sensor substrates with interdigitated gold electrodes. The sensors exhibited excellent stability and reproducible resistance change under various relative humidity percentages (9-90% RH) with negligible effect of background environment. For instance, the response to 90% RH at room temperature was about five orders of magnitude (∼1.39 × 105) and the response time (Tres) was ∼24 s. The reaction/recovery times of the sensors were compared with commercial humidity sensor to show that the reaction times in this work are not given by the surface reaction of water vapor on the sensor surfaces, rather these are mainly influenced by the experimental setup. The sensor response increased up to 3 mol% Co-contents and then decreased for 5 mol% Co-contents. Based on the experimental results, the surface reaction of humidity is discussed related to specific surface area, average grain size and cobalt contents to understand the humidity sensing mechanism.

Remarkable optical red shift and extremely high optical absorption coefficient of V-Ga co-doped TiO2

Science.gov (United States)

Deng, Quanrong; Han, Xiaoping; Gao, Yun; Shao, Guosheng

2012-07-01

A first attempt has been made to study the effect of codoping of transition metal and sp metal on the electronic structure and associated optical properties of TiO2, through V-Ga codoped thin films. V-Ga codoped rutile TiO2 films were fabricated on fused quartz substrates using pulsed laser ablation, followed by heat treatment at high temperatures. Gigantic redshift in the optical absorption edge was observed in V-Ga co-doped TiO2 materials, from UV to infrared region with high absorption coefficient. Through combined structural characterization and theoretical modeling, this is attributed to the p-d hybridization between the two metals. This leads to additional energy bands to overlap with the minimum of the conduction band, leading to remarkably narrowed band gap free of mid-gap states. The direct-gap of the co-doped phase is key to the remarkably high optical absorption coefficient of the coped titania.

Highly efficient enrichment of phosphopeptides from HeLa cells using hollow magnetic macro/mesoporous TiO2 nanoparticles.

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Hong, Yayun; Zhan, Qiliang; Pu, Chenlu; Sheng, Qianying; Zhao, Hongli; Lan, Minbo

2018-09-01

In this work, hollow magnetic macro/mesoporous TiO 2 nanoparticles (denoted as Fe 3 O 4 @H-fTiO 2 ) were synthesized by a facile "hydrothermal etching assisted crystallization" route to improve the phosphopeptide enrichment efficiency. The porous nanostructure of TiO 2 shell and large hollow space endowed the Fe 3 O 4 @H-fTiO 2 with a high surface area (144.71 m 2 g -1 ) and a large pore volume (0.52 cm 3 g -1 ), which could provide more affinity sites for phosphopeptide enrichment. Besides, the large pore size of TiO 2 nanosheets and large hollow space could effectively prevent the "shadow effect", thereby facilitating the diffusion and release of phosphopeptides. Compared with the hollow magnetic mesoporous TiO 2 with small and deep pores (denoted as Fe 3 O 4 @H-mTiO 2 ) and solid magnetic macro/mesoporous TiO 2 , the Fe 3 O 4 @H-fTiO 2 nanoparticles showed a better selectivity (molar ratio of α-casein/BSA up to 1:10000) and a higher sensitivity (0.2 fmol/μL α-casein) for phosphopeptide enrichment. Furthermore, 1485 unique phosphopeptides derived from 660 phosphoproteins were identified from HeLa cell extracts after enrichment with Fe 3 O 4 @H-fTiO 2 nanoparticles, further demonstrating that the Fe 3 O 4 @H-fTiO 2 nanoparticles had a high-efficiency performance for phosphopeptide enrichment. Taken together, the Fe 3 O 4 @H-fTiO 2 nanoparticles will have unique advantages in phosphoproteomics analysis. Copyright © 2018 Elsevier B.V. All rights reserved.

Photocatalytic application of TiO2/SiO2-based magnetic nanocomposite (Fe3O4@SiO2/TiO2 for reusing of textile wastewater

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Laleh Enayati Ahangar

2016-01-01

Full Text Available In this research we have developed a treatment method for textile wastewater by TiO2/SiO2-based magnetic nanocomposite. Textile wastewater includes a large variety of dyes and chemicals and needs treatments. This manuscript presents a facile method for removing dyes from the textile wastewater by using TiO2/SiO2-based nanocomposite (Fe3O4@SiO2/TiO2 under UV irradiation. This magnetic nanocomposite, as photocatalytically active composite, is synthesized via solution method in mild conditions. A large range of cationic, anionic and neutral dyes including: methyl orange, methylene blue, neutral red, bromocresol green and methyl red are used for treatment investigations. Neutral red and bromocresol green have good results in reusing treatment. The high surface area of nanocomposites improve the kinetic of wastewater treatment. In this method, by using the magnetic properties of Fe3O4 nanoparticles, TiO2-based photocatalyst could be separated and reused for 3 times. The efficiency of this method is respectively 100% and 65% for low concentration (10 ppm and high concentration (50 ppm of neutral red and bromocrosol green after 3 h treatment. The efficiency of treatment using the second used nanocomposite was 90% for 10 ppm of the same dyes.

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%.

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

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

High Photocatalytic Performance of Two Types of Graphene Modified TiO2 Composite Photocatalysts

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Zhang, Jun; Li, Sen; Tang, Bo; Wang, Zhengwei; Ji, Guojian; Huang, Weiqiu; Wang, Jinping

2017-07-01

High quality and naturally continuous structure of three-dimensional graphene network (3DGN) endow it a promising candidate to modify TiO2. Although the resulting composite photocatalysts display outstanding performances, the lacking of active sites of the 3DGN not only goes against a close contact between the graphene basal plane and TiO2 nanoparticles (weaken electron transport ability) but also limits the efficient adsorption of pollutant molecules. Similar with surface functional groups of the reduced graphene oxide (RGO) nanosheets, surface defects of the 3DGN can act as the adsorption sites. However, the defect density of the 3DGN is difficult to control (a strict cool rate of substrate and a strict flow of precursor gas are necessary) because of its growth approach (chemical vapor deposition method). In this study, to give full play to the functions of graphene, the RGO nanosheets and 3DGN co-modified TiO2 composite photocatalysts are prepared. After optimizing the mass fraction of the RGO nanosheets in the composite photocatalyst, the resulting chemical adsorption ability and yields of strong oxidizing free radicals increase significantly, indicating the synergy of the RGO nanosheets and 3DGN.

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

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

Remote sensing of potential lunar resources. 2: High spatial resolution mapping of spectral reflectance ratios and implications for nearside mare TiO2 content`

Science.gov (United States)

Melendrez, David E.; Johnson, Jeffrey R.; Larson, Stephen M.; Singer, Robert B.

1994-01-01

High spatial resolution maps illustrating variations in spectral reflectance 400/560 nm ratio values have been generated for the following mare regions: (1) the border between southern Mare Serenitatis and northern Mare Tranquillitatis (including the MS-2 standard area and Apollo 17 landing site), (2) central Mare Tranquillitatis, (3) Oceanus Procellarum near Seleucus, and (4) southern Oceanus Procellarum and Flamsteed. We have also obtained 320-1000 nm reflectance spectra of several sites relative to MS-2 to facilitate scaling of the images and provide additional information on surface composition. Inferred TiO2 abundances for these mare regions have been determined using an empirical calibration which relates the weight percent TiO2 in mature mare regolith to the observed 400/560 nm ratio. Mare areas with high TiO2 abundances are probably rich in ilmenite (FeTiO3) a potential lunar resource. The highest potential TiO2 concentrations we have identified in the nearside maria occur in central Mare Tranquillitatis. Inferred TiO2 contents for these areas are greater than 9 wt% and are spatially consistent with the highest-TiO2 regions mapped previously at lower spatial resolution. We note that the morphology of surface units with high 400/560 nm ratio values increases in complexity at higher spatial resolutions. Comparisons have been made with previously published geologic maps, Lunar Orbiter IV, and ground-based images, and some possible morphologic correlatins have been found between our mapped 400/560 nm ratio values and volcanic landforms such as lava flows, mare domes, and collapse pits.

Quasiparticle interfacial level alignment of highly hybridized frontier levels: H2O on TiO2(110).

Science.gov (United States)

Migani, Annapaola; Mowbray, Duncan J; Zhao, Jin; Petek, Hrvoje

2015-01-13

Knowledge of the frontier levels' alignment prior to photoirradiation is necessary to achieve a complete quantitative description of H2O photocatalysis on TiO2(110). Although H2O on rutile TiO2(110) has been thoroughly studied both experimentally and theoretically, a quantitative value for the energy of the highest H2O occupied levels is still lacking. For experiment, this is due to the H2O levels being obscured by hybridization with TiO2(110) levels in the difference spectra obtained via ultraviolet photoemission spectroscopy (UPS). For theory, this is due to inherent difficulties in properly describing many-body effects at the H2O-TiO2(110) interface. Using the projected density of states (DOS) from state-of-the-art quasiparticle (QP) G0W0, we disentangle the adsorbate and surface contributions to the complex UPS spectra of H2O on TiO2(110). We perform this separation as a function of H2O coverage and dissociation on stoichiometric and reduced surfaces. Due to hybridization with the TiO2(110) surface, the H2O 3a1 and 1b1 levels are broadened into several peaks between 5 and 1 eV below the TiO2(110) valence band maximum (VBM). These peaks have both intermolecular and interfacial bonding and antibonding character. We find the highest occupied levels of H2O adsorbed intact and dissociated on stoichiometric TiO2(110) are 1.1 and 0.9 eV below the VBM. We also find a similar energy of 1.1 eV for the highest occupied levels of H2O when adsorbed dissociatively on a bridging O vacancy of the reduced surface. In both cases, these energies are significantly higher (by 0.6 to 2.6 eV) than those estimated from UPS difference spectra, which are inconclusive in this energy region. Finally, we apply self-consistent QPGW (scQPGW1) to obtain the ionization potential of the H2O-TiO2(110) interface.

Evaluate humidity sensing properties of novel TiO2–WO3 composite material

International Nuclear Information System (INIS)

Lin, Wang-De; Lai, De-Sheng; Chen, Min-Hung; Wu, Ren-Jang; Chen, Fu-Chou

2013-01-01

Graphical abstract: TiO 2 –WO 3 (1:1) showed better humidity sensing properties than others within the range of 12–90% relative humidity (RH), the response and recovery time were about 20 s and 160 s, respectively. Compared to the previous studies, the prepared sensor exhibits higher sensitivity (S = 451) and the low hysteresis value was around 0.13% at 32% RH. - Highlights: • Novel TiO 2 –WO 3 composite material was prepared for humidity sensor. • The sensor exhibits higher sensitivity (S = 451). • Low hysteresis value was around 0.13% at 32% RH. - Abstract: A novel TiO 2 –WO 3 composite material was prepared using a different proportion of TiO 2 and WO 3 to that investigated in previous studies. The obtained mesoporous material was characterized using X-ray diffraction, Fourier transform infrared spectrometry, transmission electron microscopy, energy dispersive X-ray spectroscopy, and N 2 adsorption-desorption techniques. The humidity-sensing properties were measured using an inductance, capacitance and resistance analyzer. The results demonstrated that the TiO 2 –WO 3 sample with a ratio of 1:1 showed better humidity sensing properties. Compared to previous studies, the prepared sensor exhibited higher sensitivity (S = 451) and the lower hysteresis value was around 0.13% at 32% RH. Complex impedance analysis indicated that the enhanced humidity sensitivity was probably due to spherical Brunauer–Emmett–Teller surface area and the hetero-junction between TiO 2 –WO 3 thin films, while the impedance varied about three orders of magnitude. Our results demonstrated the potential application of TiO 2 –WO 3 composite for fabricating high performance humidity sensors

A pressure tuned stop-flow atomic layer deposition process for MoS2 on high porous nanostructure and fabrication of TiO2/MoS2 core/shell inverse opal structure

Science.gov (United States)

Li, Xianglin; Puttaswamy, Manjunath; Wang, Zhiwei; Kei Tan, Chiew; Grimsdale, Andrew C.; Kherani, Nazir P.; Tok, Alfred Iing Yoong

2017-11-01

MoS2 thin films are obtained by atomic layer deposition (ALD) in the temperature range of 120-150 °C using Mo(CO)6 and dimethyl disulfide (DMDS) as precursors. A pressure tuned stop-flow ALD process facilitates the precursor adsorption and enables the deposition of MoS2 on high porous three dimensional (3D) nanostructures. As a demonstration, a TiO2/MoS2 core/shell inverse opal (TiO2/MoS2-IO) structure has been fabricated through ALD of TiO2 and MoS2 on a self-assembled multilayer polystyrene (PS) structure template. Due to the self-limiting surface reaction mechanism of ALD and the utilization of pressure tuned stop-flow ALD processes, the as fabricated TiO2/MoS2-IO structure has a high uniformity, reflected by FESEM and FIB-SEM characterization. A crystallized TiO2/MoS2-IO structure can be obtained through a post annealing process. As a 3D photonic crystal, the TiO2/MoS2-IO exhibits obvious stopband reflecting peaks, which can be adjusted through changing the opal diameters as well as the thickness of MoS2 layer.

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.

Synthesis and photocatalytic activity for TiO2 nanoparticles as air purification

Directory of Open Access Journals (Sweden)

Haider Adawiya

2018-01-01

Full Text Available In the present work, titanium dioxide (TiO2 nanoparticles (NP’s were prepared using sol-gel process from Titanium Tetrachloride (TiCl4 as a precursor with calcinations at two temperatures (500 and 900 °C. The effect of calcinations temperatures on the structural, optical, morphological and Root Mean Square (roughness properties were investigated by means of Scanning Electron Microscopy, X-ray Diffraction (XRD, and Atomic Force Microscopy (AFM. Bacterial inactivation was evaluated using TiO2-coated Petri dishes. A thin layer of photocatalytic TiO2 powder was deposited on glass substrate in order to investigate the self-cleaning effect of TiO2 nanoparticles in indoor and outdoor applications. Ultra-hydrophilicity was assessed by measuring the contact angle and it evaluated photolysis properties through the degradation of potassium permanganate (KMnO4 under direct sunlight. XRD analysis indicated that the structure of TiO2 was anatase at 500 °C and rutile at 900 °C calcination temperatures. As the calcination temperature increases, the crystallinity is improved and the crystallite size becomes larger. Coated films of TiO2 made the has permeability, low water contact angle and good optical activity. These are properties essential for the application of the surface of the self-cleaning. The final results illustrate that titanium dioxide can be used in the build materials to produce coated surfaces in order to minimize air pollutants that are placed in microbiologically sensitive circumference like hospitals and the food factory.

Selective adsorption of thiophenic compounds from fuel over TiO2/SiO2 under UV-irradiation.

Science.gov (United States)

Miao, Guang; Ye, Feiyan; Wu, Luoming; Ren, Xiaoling; Xiao, Jing; Li, Zhong; Wang, Haihui

2015-12-30

This study investigates selective adsorption of thiophenic compounds from fuel over TiO2/SiO2 under UV-irradiation. The TiO2/SiO2 adsorbents were prepared and then characterized by N2 adsorption, X-ray diffraction and X-ray photoelectron spectroscopy. Adsorption isotherms, selectivity and kinetics of TiO2/SiO2 were measured in a UV built-in batch reactor. It was concluded that (a) with the employment of UV-irradiation, high organosulfur uptake of 5.12 mg/g was achieved on the optimized 0.3TiO2/0.7SiO2 adsorbent at low sulfur concentration of 15 ppmw-S, and its adsorption selectivity over naphthalene was up to 325.5; (b) highly dispersed TiO2 served as the photocatalytic sites for DBT oxidation, while SiO2 acted as the selective adsorption sites for the corresponding oxidized DBT using TiO2 as a promoter, the two types of active sites worked cooperatively to achieve the high adsorption selectivity of TiO2/SiO2; (c) The kinetic rate-determining step for the UV photocatalysis-assisted adsorptive desulfurization (PADS) over TiO2/SiO2 was DBT oxidation; (d) consecutive adsorption-regeneration cycles suggested that the 0.3TiO2/0.7SiO2 adsorbent can be regenerated by acetonitrile washing followed with oxidative air treatment. This work demonstrated an effective PADS approach to greatly enhance adsorption capacity and selectivity of thiophenic compounds at low concentrations for deep desulfurization under ambient conditions. Copyright © 2015 Elsevier B.V. All rights reserved.

Photocatalytic Degradation of Bisphenol A from Aqueous Solutions using TiO2 Nanoparticles and UV Illumination

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Ramzan ali Dianati

2014-12-01

Full Text Available Background and Purpose: Bisphenol A (BPA is used to make certain plastics and epoxy resins. It is a non-biodegradable compound, and poses health risks to both humans and animals. The purpose of this study was to evaluate decomposition efficiency of BPA from aqueous solutions using UV irradiation. Materials and Methods: In this study, the photodegradation of BPA in water were carried out in a reactor equipped 6 W UV lamp. In order to obtain the optimum operational conditions, parameters such as BPA concentration (1-50 mg/l, TiO2 dosage (0.025-2 g/l, and pH (3-11 were evaluated. BPA concentration was measured by high-performance liquid chromatography. Results: The highest degradation was 90% and achieved in 60 min. BPA degradation efficiency can be effectively improved by increasing pH, decreasing the initial concentration and increasing TiO2 dosage. The optimal dose of TiO2 was measured at 0.5 g/l. The degradation decreases with increasing TiO2 dosage. Conclusion: Photocatalytic degradation by using TiO2 and low power UV lamp is applicable.

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.

Highly Enhanced Photoreductive Degradation of Polybromodiphenyl Ethers with g-C3N4/TiO2 under Visible Light Irradiation

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Weidong Ye

2017-04-01

Full Text Available A series of high activity photocatalysts g-C3N4-TiO2 were synthesized by simple one-pot thermal transformation method and characterized by transmission electron microscopy (TEM, scanning electron microscopy (SEM, X-ray diffraction (XRD, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller (BET surface area, and ultraviolet–visible diffuse reflectance spectroscopy (UV-Vis-DRS. The g-C3N4-TiO2 samples show highly improved photoreductive capability for the degradation of polybromodiphenyl ethers compared with g-C3N4 under visible light irradiation. Among all the hybrids, 0.02-C3N4-TiO2 with 2 wt % g-C3N4 loaded shows the highest reaction rate, which is 15 times as high as that in bare g-C3N4. The well-matched band gaps in heterojunction g-C3N4-TiO2 not only strengthen the absorption intensity, but also show more effective charge carrier separation, which results in the highly enhanced photoreductive performance under visible light irradiation. The trapping experiments show that holetrapping agents largely affect the reaction rate. The rate of electron accumulation in the conductive band is the rate-determining step in the degradation reaction. A possible photoreductive mechanism has been proposed.

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.

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

International Nuclear Information System (INIS)

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

2014-01-01

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

Effect of TiO2 on thermal, structural and third-order nonlinear optical properties of Ca-La-B-O glass system

International Nuclear Information System (INIS)

Biswas, Kaushik; Sontakke, Atul D.; Annapurna, K.

2010-01-01

A series of calcium lanthanum metaborate glasses in the composition (wt%) of 23.88CaO-28.33La 2 O 3 -47.79B 2 O 3 modified with TiO 2 up to 20 wt% are prepared by a melt quenching technique to study the influence of TiO 2 on their thermal, structural, linear and nonlinear optical properties. The differential thermal analysis (DTA) studies have demonstrated significant effects due to the presence of TiO 2 on the glass forming ability and crystallization situations. The glass with 15 wt% TiO 2 has achieved a eutectic composition and also exhibited a better glass forming ability among the glasses studied. The FT-IR spectra of these glasses show mainly vibration modes corresponding to stretching of BO 3 trigonal, BO 4 tetrahedral units and of B-O-B bending bonds. At higher concentrations of TiO 2 , development of vibration band around 400 cm -1 has indicated the formation of TiO 6 structural units in the glass network. The red shift of optical absorption edge (UV cutoff) shows a monotonous decrease in direct and indirect optical band gap energies (E opt ) with an increase of TiO 2 content in the glasses based on their absorption spectra. The optical transparency of these glasses is found to be varied from 64 to 87% within the wavelength range 450-1100 nm depending on the TiO 2 content. Besides these studies, linear refractive indices, the nonlinear optical properties of these glasses have also been evaluated.

Photocatalytic Degradation of Methylene Blue Using TiO2 Impregnated Diatomite

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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.

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%.

Data on the effect of improved TiO2/FTO interface and Ni(OH)2 cocatalyst on the photoelectrochemical performances and stability of CdS cased ZnIn2S4/TiO2 heterojunction.

Science.gov (United States)

Mahadik, Mahadeo A; Shinde, Pravin S; Lee, Hyun Hwi; Cho, Min; Jang, Jum Suk

2018-04-01

This data article presents the experimental evidences of the effect of TiO 2 -fluorine doped tin oxide interface annealing and Ni(OH) 2 cocatalysts on the photoelectrochemical, structural, morphological and optical properties of Ni(OH) 2 /CdS/ZnIn 2 S 4 /TiO 2 heterojunction. The Raman spectroscopy exhibits the sharp features of the rutile phase of TiO 2 and in agreement with the X-ray diffraction data. The band gap energy of the 500 °C sample was found to be 3.12 eV, further it was increased to 3.20, 3.22 eV for samples annealed at 600 and 700 °C respectively. The decrease in the band gap energy at 500 °C related to the oxygen vacancies and was analysed by photoluminescence spectroscopy analysis. The synthesis, characterization methods and other experimental details of TiO 2 based heterostructure are also provided. The presence of CdS and ZnIn 2 S 4 coating on surface of TiO 2 electrodes providing a high surface area, extended visible absorption and helps to improve the change separation. This data article contains data related to the research article entitled "Highly efficient and stable 3D Ni(OH) 2 /CdS/ZnIn 2 S 4 /TiO 2 heterojunction under solar light: Effect of an improved TiO 2 /FTO interface and cocatalyst" (Mahadik et al., 2017) [1].

Dissociative and molecular oxygen chemisorption channels on reduced rutile TiO2(110): A high-resolution STM study

DEFF Research Database (Denmark)

Lira, Estephania; Hansen, Jonas Ørbæk; Huo, Peipei

2010-01-01

High-resolution scanning tunneling microscopy (STM) and temperature-programmed desorption (TPD) were used to study the interaction of O2 with reduced TiO2(110)–(1 × 1) crystals. STM is the technique of choice to unravel the relation between vacancy and non-vacancy assisted O2 dissociation channel...... in the near-surface region of reduced TiO2(110) crystals, the kinetics of the two O2 dissociation channels as well as the kinetics of the diffusion and reaction of Ti interstitials....

TiO2 nanosheets synthesized by atomic layer deposition for photocatalysis

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Riyanto Edy

2016-10-01

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

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

Highly efficient hybrid photovoltaics based on hyperbranched three-dimensional TiO2 electron transporting materials

KAUST Repository

Mahmood, Khalid; Swain, Bhabani Sankar; Amassian, Aram

2015-01-01

A 3D hyperbranched TiO2 electron transporting material is demonstrated, which exhibits superior carrier transport and lifetime, as well as excellent infiltration, leading to highly efficient mesostructured hybrid solar cells, such as lead-halide perovskites (15.5%) and dye-sensitized solar cells (11.2%).

Highly efficient hybrid photovoltaics based on hyperbranched three-dimensional TiO2 electron transporting materials

KAUST Repository

Mahmood, Khalid

2015-03-23

A 3D hyperbranched TiO2 electron transporting material is demonstrated, which exhibits superior carrier transport and lifetime, as well as excellent infiltration, leading to highly efficient mesostructured hybrid solar cells, such as lead-halide perovskites (15.5%) and dye-sensitized solar cells (11.2%).

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)

Sb2S3 surface modification induced remarkable enhancement of TiO2 core/shell nanowries solar cells

International Nuclear Information System (INIS)

Meng, Xiuqing; Wang, Xiaozhou; Zhong, Mianzeng; Wu, Fengmin; Fang, Yunzhang

2013-01-01

This study presents the fabrication of a novel dye-sensitized solar cell with Sb 2 S 3 -modified TiO 2 nanowire (NW) arrays/TiO 2 nanoparticles (NP) (TiO 2(NWs) /TiO 2(NPs) /Sb 2 S 3 ) as the anodes and N719 dye as the sensitizer. A solar conversion efficiency of 4.91% at 1 sun illumination was achieved for the composite cell, which is markedly higher than the efficiency rates obtained using TiO 2 and TiO 2(NWs) /Sb 2 S 3 /TiO 2(NPs) NW cells, calculated at 2.36% and 3.11%, respectively. The improved efficiency results from the large surface area of the NPs, as well as the expansion of the light absorption region and high absorption coefficient by Sb 2 S 3 surface modification. - Graphical abstract: A novel TiO 2(NWs) /TiO 2(NPs) /Sb 2 S 3 dye sensitized solar cells (DSSCs) is fabricated, a solar conversion efficiency of 4.91 % at 1 sun illumination is achieved. Highlights: ► We fabricate sandwich structured TiO 2 dye-sensitized solar cells. ► The anode of the solar cells consist of Sb 2 S 3 modified TiO 2 nanowire arrays/TiO 2 nanopartices. ► A solar conversion efficiency of 4.91% at 1 sun illumination is achieved. ► The high efficiency results from large surface area and expanded light adsorption of the anode

Enhanced photoelectrocatalytic degradation of 2,4-dichlorophenoxyacetic acid by CuInS2 nanoparticles deposition onto TiO2 nanotube arrays

International Nuclear Information System (INIS)

Liu Ronghua; Liu Yutang; Liu Chengbin; Luo Shenglian; Teng Yarong; Yang Lixia; Yang Renbin; Cai Qingyun

2011-01-01

Research highlights: → The photocatalytic application of CuInS 2 with a direct band gap of about 1.5 eV and a high absorption coefficient remains unknown. → We describe an impulse electrodeposition approach to deposit CuInS 2 nanoparticles in uniform size of about 20 nm onto the top surface of the highly oriented TiO 2 NT arrays while minimizing the clogging of the tube entrances. → The novel photocatalyst exhibits a highly visible-light photocatalytic degradation activity for the target organic pollutant. → Moreover, the stability of the modified TiO 2 NT is good. → Therefore, CuInS 2 nanoparticles modified TiO 2 NT photocatalysts have potential utility in practical purification of organic wastewater. - Abstract: Surface modification of TiO 2 nanotube (NT) arrays with CuInS 2 nanoparticles (NPs) for photocatalytic degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) was reported. A pulse electrodeposition technique was used to prepare the CuInS 2 NPs, and the resulted CuInS 2 NPs, with a uniform size of about 20 nm, were found to deposit on the top surface of the highly oriented TiO 2 NT while without clogging the tube entrances. Compared with the unmodified TiO 2 NT, the CuInS 2 NPs modified TiO 2 NT (CuInS 2 -TiO 2 NT) showed significantly enhanced photocatalytic activity towards 2,4-D under visible light. After 160 min irradiation, the removal rate of 2,4-D is 100% by using CuInS 2 -TiO 2 NT, much higher than 65.2% by using the unmodified TiO 2 NT in photoelectrocatalytic process. The increased photodegradation efficiency mainly results from the improved photocurrent density as results of enhanced visible-light absorption and decreased hole-electron recombination due to the presence of narrow-band-gap p-type semiconductor CuInS 2 .

Dynamic Hydrogen Production from Methanol/Water Photo-Splitting Using Core@Shell-Structured CuS@TiO2 Catalyst Wrapped by High Concentrated TiO2 Particles

Directory of Open Access Journals (Sweden)

Younghwan Im

2013-01-01

Full Text Available This study focused on the dynamic hydrogen production ability of a core@shell-structured CuS@TiO2 photocatalyst coated with a high concentration of TiO2 particles. The rectangular-shaped CuS particles, 100 nm in length and 60 nm in width, were surrounded by a high concentration of anatase TiO2 particles (>4~5 mol. The synthesized core@shell-structured CuS@TiO2 particles absorbed a long wavelength (a short band gap above 700 nm compared to that pure TiO2, which at approximately 300 nm, leading to easier electronic transitions, even at low energy. Hydrogen evolution from methanol/water photo-splitting over the core@shell-structured CuS@TiO2 photocatalyst increased approximately 10-fold compared to that over pure CuS. In particular, 1.9 mmol of hydrogen gas was produced after 10 hours when 0.5 g of 1CuS@4TiO2 was used at pH = 7. This level of production was increased to more than 4-fold at higher pH. Cyclic voltammetry and UV-visible absorption spectroscopy confirmed that the CuS in CuS@TiO2 strongly withdraws the excited electrons from the valence band in TiO2 because of the higher reduction potential than TiO2, resulting in a slower recombination rate between the electrons and holes and higher photoactivity.

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

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.

Heterostructured TiO2/NiTiO3 Nanorod Arrays for Inorganic Sensitized Solar Cells with Significantly Enhanced Photovoltaic Performance and Stability.

Science.gov (United States)

Li, Yue-Ying; Wang, Jian-Gan; Sun, Huan-Huan; Wei, Bingqing

2018-04-11

Organic dyes used in the conventional dye-sensitized solar cells (DSSCs) suffer from poor light stability and high cost. In this work, we demonstrate a new inorganic sensitized solar cell based on ordered one-dimensional semiconductor nanorod arrays of TiO 2 /NiTiO 3 (NTO) heterostructures prepared via a facile two-step hydrothermal approach. The semiconductor heterostructure arrays are highly desirable and promising for DSSCs because of their direct charge transport capability and slow charge recombination rate. The low-cost NTO inorganic semiconductor possesses an appropriate band gap that matches well with TiO 2 , which behaves like a "dye" to enable efficient light harvesting and fast electron-hole separation. The solar cells constructed by the ordered TiO 2 /NTO heterostructure photoanodes show a significantly improved power conversion efficiency, high fill factor, and more promising, outstanding life stability. The present work will open up an avenue to design heterostructured inorganics for high-performance solar cells.

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

KAUST Repository

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

2014-01-01

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

Improved Solar-Driven Photocatalytic Performance of Highly Crystalline Hydrogenated TiO2 Nanofibers with Core-Shell Structure

Science.gov (United States)

Wu, Ming-Chung; Chen, Ching-Hsiang; Huang, Wei-Kang; Hsiao, Kai-Chi; Lin, Ting-Han; Chan, Shun-Hsiang; Wu, Po-Yeh; Lu, Chun-Fu; Chang, Yin-Hsuan; Lin, Tz-Feng; Hsu, Kai-Hsiang; Hsu, Jen-Fu; Lee, Kun-Mu; Shyue, Jing-Jong; Kordás, Krisztián; Su, Wei-Fang

2017-01-01

Hydrogenated titanium dioxide has attracted intensive research interests in pollutant removal applications due to its high photocatalytic activity. Herein, we demonstrate hydrogenated TiO2 nanofibers (H:TiO2 NFs) with a core-shell structure prepared by the hydrothermal synthesis and subsequent heat treatment in hydrogen flow. H:TiO2 NFs has excellent solar light absorption and photogenerated charge formation behavior as confirmed by optical absorbance, photo-Kelvin force probe microscopy and photoinduced charge carrier dynamics analyses. Photodegradation of various organic dyes such as methyl orange, rhodamine 6G and brilliant green is shown to take place with significantly higher rates on our novel catalyst than on pristine TiO2 nanofibers and commercial nanoparticle based photocatalytic materials, which is attributed to surface defects (oxygen vacancy and Ti3+ interstitial defect) on the hydrogen treated surface. We propose three properties/mechanisms responsible for the enhanced photocatalytic activity, which are: (1) improved absorbance allowing for increased exciton generation, (2) highly crystalline anatase TiO2 that promotes fast charge transport rate, and (3) decreased charge recombination caused by the nanoscopic Schottky junctions at the interface of pristine core and hydrogenated shell thus promoting long-life surface charges. The developed H:TiO2 NFs can be helpful for future high performance photocatalysts in environmental applications.

Facile synthesis of 3D few-layered MoS2 coated TiO2 nanosheet core-shell nanostructures for stable and high-performance lithium-ion batteries

Science.gov (United States)

Chen, Biao; Zhao, Naiqin; Guo, Lichao; He, Fang; Shi, Chunsheng; He, Chunnian; Li, Jiajun; Liu, Enzuo

2015-07-01

Uniform transition metal sulfide deposition on a smooth TiO2 surface to form a coating structure is a well-known challenge, caused mainly due to their poor affinities. Herein, we report a facile strategy for fabricating mesoporous 3D few-layered (glucose as a binder. The core-shell structure has been systematically examined and corroborated by transmission electron microscopy, scanning transmission electron microscopy, and X-ray photoelectron spectroscopy analyses. It is found that the resultant 3D FL-MoS2@TiO2 as a lithium-ion battery anode delivers an outstanding high-rate capability with an excellent cycling performance, relating to the unique structure of 3D FL-MoS2@TiO2. The 3D uniform coverage of few-layered (glucose as a binder. The core-shell structure has been systematically examined and corroborated by transmission electron microscopy, scanning transmission electron microscopy, and X-ray photoelectron spectroscopy analyses. It is found that the resultant 3D FL-MoS2@TiO2 as a lithium-ion battery anode delivers an outstanding high-rate capability with an excellent cycling performance, relating to the unique structure of 3D FL-MoS2@TiO2. The 3D uniform coverage of few-layered (<4 layers) MoS2 onto the TiO2 can remarkably enhance the structure stability and effectively shortens the transfer paths of both lithium ions and electrons, while the strong synergistic effect between MoS2 and TiO2 can significantly facilitate the transport of ions and electrons across the interfaces, especially in the high-rate charge-discharge process. Moreover, the facile fabrication strategy can be easily extended to design other oxide/carbon-sulfide/oxide core-shell materials for extensive applications. Electronic supplementary information (ESI) available: Supplementary SEM, TEM, XPS and EIS analyses. See DOI: 10.1039/c5nr03334a

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.

TiO2-Nanofillers Effects on Some Properties of Highly- Impact Resin Using Different Processing Techniques.

Science.gov (United States)

Aziz, Hawraa Khalid

2018-01-01

The criteria of conventional curing of polymethyl methacrylate do not match the standard properties of the denture base materials. This research was conducted to investigate the addition of TiO 2 nano practical on impact strength, thermal conductivity and color stability of acrylic resin cured by microwave in comparison to the conventional cured of heat-polymerized acrylic resin. 120 specimens made of high impact acrylic resin were divided into two main groups according to the type of curing (water bath, microwave), then each group was subdivided into two groups according to the addition of 3% TiO 2 nano-fillers and control group (without the addition of TiO 2 0%). Each group was subdivided according to the type of test into 3 groups with 10 specimens for each group. Data were statistically analyzed using Student t-test to detect the significant differences between tested and control groups at significance level ( P <0.05). According to curing type methods, the results showed that there was a significant decrease in impact strength of microwaved cured resin, but there was no significant difference in the thermal conductivity and color stability of resin. In addition, by using nanofiller, there was a significant increase in the impact strength and color stability with the addition of 3% TiO 2 nanofillers, but no significant difference was found in the thermal conductivity of the acrylic resin. The microwave curing of acrylic resin had no change in the color stability and thermal conductivity in comparison to the water bath, but the impact strength was decreased. The addition of 3% TiO 2 improved the impact and the color stability, but the thermal conductivity did not change.

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.

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.

Quantum Dot Sensitized Solar Cells Based on TiO2/AgInS2

Science.gov (United States)

Pawar, Sachin A.; Jeong, Jae Pil; Patil, Dipali S.; More, Vivek M.; Lee, Rochelle S.; Shin, Jae Cheol; Choi, Won Jun

2018-05-01

Quantum dot heterojunctions with type-II band alignment can efficiently separate photogenerated electron-hole pairs and, hence, are useful for solar cell studies. In this study, a quantum dot sensitized solar cell (QDSSC) made of TiO2/AgInS2 is achieved to boost the photoconversion efficiency for the TiO2-based system by varying the AgInS2 layer's thickness. The TiO2 nanorods array film is prepared by using a simple hydrothermal technique. The formation of a AgInS2 QD-sensitized TiO2-nanorod photoelectrode is carried out by successive ionic layer adsorption and reaction (SILAR) technique. The effect of the QD layer on the performance of the solar cell is studied by varying the SILAR cycles of the QD coating. The synthesized electrode materials are characterized by using X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, high resolution transmission electron microscopy and solar cell performances. The results indicate that the nanocrystals have effectively covered the outer surfaces of the TiO2 nanorods. The interfacial structure of quantum dots (QDs)/TiO2 is also investigated, and the growth interface is verified. A careful comparison between TiO2/AgInS2 sensitized cells reveals that the trasfer of electrons and hole proceeds efficiently, the recombination is suppressed for the optimum thickness of the QD layer and light from the entire visible spectrum is utilised. Under AM 1.5G illumination, a high photocurrent of 1.36 mAcm-2 with an improved power conversion efficiency of 0.48% is obtained. The solar cell properties of our photoanodes suggest that the TiO2 nanorod array films co-sensitized by AgInS2 nanoclusters have potential applications in solar cells.

Proline adsorption on TiO 2(1 1 0) single crystal surface: A study by high resolution photoelectron spectroscopy

Science.gov (United States)

Fleming, G. J.; Adib, K.; Rodriguez, J. A.; Barteau, M. A.; Idriss, H.

2007-12-01

The surface chemistry and binding of DL-proline were investigated on the oxidised (stoichiometric) and reduced (sub-stoichiometric) TiO 2(1 1 0) single crystal surfaces. TiO 2 was chosen as the substrate as it best represents the surface of a biomedical implant, which bio-molecules interact with during the healing of bone/teeth fractures (molecular recognition). High resolution X-ray photoelectron spectroscopy (HR-XPS) studies of the C1s and N1s regions revealed that DL-proline is present in two forms (dissociated and zwitterionic) on the oxidised TiO 2 surface. On TiO 2(1 1 0) surfaces reduced by Ar + sputtering, a significant increase in the amount of zwitterionic proline at the surface was detected when compared with the oxidised surface. Study of the temperature effect showed that in both cases the zwitterionic structure was the less stable structure. The reason for its relative instability appears to be thermodynamic.

Spontaneous Synthesis of Highly Crystalline TiO2 Compact/Mesoporous Stacked Films by a Low-Temperature Steam-Annealing Method for Efficient Perovskite Solar Cells.

Science.gov (United States)

Sanehira, Yoshitaka; Numata, Youhei; Ikegami, Masashi; Miyasaka, Tsutomu

2018-05-23

Highly crystalline TiO 2 nanostructured films were synthesized by a simple steam treatment of a TiCl 4 precursor film under a saturated water vapor atmosphere at 125 °C, here referred to as the steam-annealing method. In a single TiO 2 film preparation step, a bilayer structure comprising a compact bottom layer and a mesoporous surface layer was formed. The mesoporous layer was occupied by bipyramidal nanoparticles, with a composite phase of anatase and brookite crystals. Despite the low-temperature treatment process, the crystallinity of the TiO 2 film was high, comparable with that of the TiO 2 film sintered at 500 °C. The compact double-layered TiO 2 film was applied to perovskite solar cells (PSCs) as an electron-collecting layer. The PSC exhibited a maximum power conversion efficiency (PCE) of 18.9% with an open-circuit voltage ( V OC ) of 1.15 V. The PCE and V OC were higher than those of PSCs using a TiO 2 film formed by 500 °C sintering.

Thermoluminescence response and glow curve structure of Sc2TiO5 ß-irradiated

International Nuclear Information System (INIS)

Muñoz, I.C.; Brown, F.; Durán-Muñoz, H.; Cruz-Zaragoza, E.; Durán-Torres, B.; Alvarez-Montaño, V.E.

2014-01-01

Discandium titanate (Sc 2 TiO 5 ) powder was synthesized in order to analyze its thermoluminescence (TL) response. The TL glow curve structure shows two peaks: at 453–433 K and at 590–553 K. The TL beta dose–response has a linear behavior over the dose range 50–500 Gy. The T stop preheat method shows five glow peaks that were taken into account to calculate the kinetic parameters using the CGCD procedure. TL results support the possible use of Sc 2 TiO 5 as a new phosphor in high ß-dose dosimetry. - Highlights: • Discandium titanate was synthesized, and its TL properties were analyzed. • The beta dose–response has a linear behavior on the dose range 50–500 Gy. • The kinetic parameters were obtained by the CGCD procedure. • Results support the possible use of Sc 2 TiO 5 as a new phosphor for ß-dose dosimetry

Pressure-Induced Polyamorphic Transition in Nanoscale TiO2

International Nuclear Information System (INIS)

Swamy, Varghese; Muddle, Barry C.

2009-01-01

The detection and characterization of pressure-induced amorphization in 20 GPa and ambient temperature is documented. The characterization employed in situ high-pressure angle-dispersive synchrotron X-ray diffraction and Raman spectroscopy in diamond-anvil cells. Comparative Raman spectroscopy allows the local structures of the high-density amorphous (HDA) form obtained at high pressures and its low-pressure (<10-15 GPa) low-density amorphous (LDA) analogue to be related to the baddeleyite-TiO2 and TiO2-II structures, respectively. The pressure-induced amorphization and the HDA-LDA transition in nanoscale TiO2 bear broad similarities to transitions in the Si and H2O systems.

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.

Enhancing photocatalytic activity by using TiO2-MgO core-shell-structured nanoparticles

International Nuclear Information System (INIS)

Jung, Hyun Suk; Lee, Jung-Kun; Nastasi, Michael; Kim, Jeong-Ryeol; Lee, Sang-Wook; Kim, Jin Young; Park, Jong-Sung; Hong, Kug Sun; Shin, Hyunho

2006-01-01

Hygroscopic Mg(OH) 2 gel was topotactically decomposed on TiO 2 particle surfaces, resulting in highly nanoporous MgO-coated TiO 2 particles. The highly hygroscopic and nanoporous MgO shell absorbed more water molecules and hydroxyl groups from the environment to yield an improved photocatalytic property of the core-shell particles as compared to the uncoated TiO 2 counterpart

Nanoimprinted distributed feedback lasers comprising TiO2 thin films

DEFF Research Database (Denmark)

Vannahme, Christoph; Smith, Cameron; Leung, Michael C.

2013-01-01

Design guidelines for optimizing the sensing performance of nanoimprinted second order distributed feedback dye lasers are presented. The guidelines are verified by experiments and simulations. The lasers, fabricated by UV-nanoimprint lithography into Pyrromethene doped Ormocomp thin films on glass......, have their sensor sensitivity enhanced by a factor of up to five via the evaporation of a titanium dioxide (TiO2) waveguiding layer. The influence of the TiO2 layer thickness on the device sensitivity is analyzed with a simple model that accurately predicts experimentally measured wavelength shifts...

The influence of material type and composition of TiO2- ZnO on manufacturing of paste for the application of DSSC

Science.gov (United States)

Retnaningsih, L.; Muliani, L.; Aggraini, P. N.; Hidayat, J.

2016-11-01

Research, fabrication and material selection for the application of Dye- sensitized solar cell (DSSC) has been performed on glass FTO (Flour Tin Oxide). The material is used in the form of TiO2 paste, TiO2 powder and ZnO powder. Dye-sensitized solar cell (DSSC), is a fotoelektrokimia-based solar cells where the absorption process light done by the dye molecules and the process of separation of inorganic semiconductor materials by charge of Titanium dioxide (TiO2) and Zinc oxide (ZnO). The purpose of this research is to know the exact composition of TiO2 and ZnO materials in order to produce the best efficiency with DSSC. On this research was done making prototype dye-sensitized solar cell using dye Z 907, and semiconductor nanoparticles TiO2 and ZnO powder that is made into a paste by mixing different composition in two variations of samples: A = ZnO (powder) + 40% TiO2 (powder) and B = 60% TiO2 (powder) (40%) + TiO2 (pasta) 60%. The second variation of this high efficiency is value at sample B i.e. TiO2 (powder) + 40% TiO2 (paste) of 60%.

The influence of material type and composition of TiO2- ZnO on manufacturing of paste for the application of DSSC

International Nuclear Information System (INIS)

Retnaningsih, L.; Muliani, L.; Aggraini, P. N.; Hidayat, J.

2016-01-01

Research, fabrication and material selection for the application of Dye- sensitized solar cell (DSSC) has been performed on glass FTO (Flour Tin Oxide). The material is used in the form of TiO 2 paste, TiO 2 powder and ZnO powder. Dye-sensitized solar cell (DSSC), is a fotoelektrokimia-based solar cells where the absorption process light done by the dye molecules and the process of separation of inorganic semiconductor materials by charge of Titanium dioxide (TiO 2 ) and Zinc oxide (ZnO). The purpose of this research is to know the exact composition of TiO 2 and ZnO materials in order to produce the best efficiency with DSSC. On this research was done making prototype dye-sensitized solar cell using dye Z 907, and semiconductor nanoparticles TiO 2 and ZnO powder that is made into a paste by mixing different composition in two variations of samples: A = ZnO (powder) + 40% TiO 2 (powder) and B = 60% TiO 2 (powder) (40%) + TiO 2 (pasta) 60%. The second variation of this high efficiency is value at sample B i.e. TiO 2 (powder) + 40% TiO 2 (paste) of 60%. (paper)

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.

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.

Visible-light-driven photoelectrochemical and photocatalytic performances of Cr-doped SrTiO3/TiO2 heterostructured nanotube arrays.

Science.gov (United States)

Jiao, Zhengbo; Chen, Tao; Xiong, Jinyan; Wang, Teng; Lu, Gongxuan; Ye, Jinhua; Bi, Yingpu

2013-01-01

Well-aligned TiO2 nanotube arrays have become of increasing significance because of their unique highly ordered array structure, high specific surface area, unidirectional charge transfer and transportation features. However, their poor visible light utilization as well as the high recombination rate of photoexcited electron-hole pairs greatly limited their practical applications. Herein, we demonstrate the fabrication of visible-light-responsive heterostructured Cr-doped SrTiO3/TiO2 nanotube arrays by a simple hydrothermal method, which facilitate efficient charge separation and thus improve the photoelectrochemical as well as photocatalytic performances.

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 ...

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.

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.

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

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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.

Rutile IrO2/TiO2 superlattices: A hyperconnected analog to the Ruddelsden-Popper structure

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Kawasaki, Jason K.; Baek, David; Paik, Hanjong; Nair, Hari P.; Kourkoutis, Lena F.; Schlom, Darrell G.; Shen, Kyle M.

2018-05-01

Dimensionality and connectivity among octahedra play important roles in determining the properties, electronic structure, and phase transitions of transition-metal oxides. Here we demonstrate the epitaxial growth of (110)-oriented alternating layers of IrO2 and TiO2, both of which have the rutile structure. These (IrO2)n/(TiO2)2 superlattices consist of IrO6 and TiO6 octahedra tiled in a hyperconnected, edge- and corner-sharing network. Despite the large lattice mismatch between constituent layers (Δ d∥=-2.1 % and Δ c =+6.6 % ), our reactive molecular-beam epitaxy-grown superlattices show high structural quality as determined by x-ray diffraction and sharp interfaces as observed by transmission electron microscopy. The large strain at the interface is accommodated by an ordered interfacial reconstruction. The superlattices show persistent metallicity down to n =3 atomic layers, and angle-resolved photoemission spectroscopy measurements reveal quantized sub-bands with signatures of IrO2-IrO2 interlayer coupling.

Lithium recovery from salt lake brine by H2TiO3.

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Chitrakar, Ramesh; Makita, Yoji; Ooi, Kenta; Sonoda, Akinari

2014-06-21

The details of the ion exchange properties of layered H2TiO3, derived from the layered Li2TiO3 precursor upon treatment with HCl solution, with lithium ions in the salt lake brine (collected from Salar de Uyuni, Bolivia) are reported. The lithium adsorption rate is slow, requiring 1 d to attain equilibrium at room temperature. The adsorption of lithium ions by H2TiO3 follows the Langmuir model with an adsorptive capacity of 32.6 mg g(-1) (4.7 mmol g(-1)) at pH 6.5 from the brine containing NaHCO3 (NaHCO3 added to control the pH). The total amount of sodium, potassium, magnesium and calcium adsorbed from the brine was lithium ions from the brine containing competitive cations such as sodium, potassium, magnesium and calcium in extremely large excess. The results indicate that the selectivity order Li(+) ≫ Na(+), K(+), Mg(2+), Ca(2+) originates from a size effect. The H2TiO3 can be regenerated and reused for lithium exchange in the brine with an exchange capacity very similar to the original H2TiO3.

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

International Nuclear Information System (INIS)

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

2010-01-01

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

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

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

2016-10-01

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

Visible-Light-Driven, Dye-Sensitized TiO2 Photo-Catalyst for Self-Cleaning Cotton Fabrics

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Ishaq Ahmad

2017-11-01

Full Text Available We report here the photo-catalytic properties of dye-sensitized TiO2-coated cotton fabrics. In this study, visible-light-driven, self-cleaning cotton fabrics were developed by coating the cotton fabrics with dye-sensitized TiO2. TiO2 nano-sol was prepared via the sol-gel method and the cotton fabric was coated with this nano-sol by the dip-pad–dry-cure method. In order to enhance the photo-catalytic properties of this TiO2-coated cotton fabric under visible light irradiation, the TiO2-coated cotton fabric was dyed with a phthalocyanine-based reactive dye, C.I. Reactive Blue 25 (RB-25, as a dye sensitizer for TiO2. The photo-catalytic self-cleaning efficiency of the resulting dye/TiO2-coated cotton fabrics was evaluated by degradation of Rhodamine B (RhB and color co-ordinate measurements. Dye/TiO2-coated cotton fabrics show very good photo-catalytic properties under visible light.

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

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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.

Adsorption and photocatalysis for methyl orange and Cd removal from wastewater using TiO2/sewage sludge-based activated carbon nanocomposites

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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.

Ammonia Sensing Behaviors of TiO2-PANI/PA6 Composite Nanofibers

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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.

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

Photocatalytic decolorization of basic dye by TiO2 nanoparticle in photoreactor

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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.

Preparation of MoS2/TiO2 based nanocomposites for photocatalysis and rechargeable batteries: progress, challenges, and perspective.

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Chen, Biao; Meng, Yuhuan; Sha, Junwei; Zhong, Cheng; Hu, Wenbin; Zhao, Naiqin

2017-12-21

The rapidly increasing severity of the energy crisis and environmental degradation are stimulating the rapid development of photocatalysts and rechargeable lithium/sodium ion batteries. In particular, MoS 2 /TiO 2 based nanocomposites show great potential and have been widely studied in the areas of both photocatalysis and rechargeable lithium/sodium ion batteries due to their superior combination properties. In addition to the low-cost, abundance, and high chemical stability of both MoS 2 and TiO 2 , MoS 2 /TiO 2 composites also show complementary advantages. These include the strong optical absorption of TiO 2 vs. the high catalytic activity of MoS 2 , which is promising for photocatalysis; and excellent safety and superior structural stability of TiO 2 vs. the high theoretic specific capacity and unique layered structure of MoS 2 , thus, these composites are exciting as anode materials. In this review, we first summarize the recent progress in MoS 2 /TiO 2 -based nanomaterials for applications in photocatalysis and rechargeable batteries. We highlight the synthesis, structure and mechanism of MoS 2 /TiO 2 -based nanomaterials. Then, advancements and strategies for improving the performance of these composites in photocatalytic degradation, hydrogen evolution, CO 2 reduction, LIBs and SIBs are critically discussed. Finally, perspectives on existing challenges and probable opportunities for future exploration of MoS 2 /TiO 2 -based composites towards photocatalysis and rechargeable batteries are presented. We believe the present review would provide enriched information for a deeper understanding of MoS 2 /TiO 2 composites and open avenues for the rational design of MoS 2 /TiO 2 based composites for energy and environment-related applications.

Mesoporous titanium dioxide (TiO2) with hierarchically 3D dendrimeric architectures: formation mechanism and highly enhanced photocatalytic activity.

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Li, Xiao-Yun; Chen, Li-Hua; Rooke, Joanna Claire; Deng, Zhao; Hu, Zhi-Yi; Wang, Shao-Zhuan; Wang, Li; Li, Yu; Krief, Alain; Su, Bao-Lian

2013-03-15

Mesoporous TiO(2) with a hierarchically 3D dendrimeric nanostructure comprised of nanoribbon building units has been synthesized via a spontaneous self-formation process from various titanium alkoxides. These hierarchically 3D dendrimeric architectures can be obtained by a very facile, template-free method, by simply dropping a titanium butoxide precursor into methanol solution. The novel configuration of the mesoporous TiO(2) nanostructure in nanoribbon building units yields a high surface area. The calcined samples show significantly enhanced photocatalytic activity and degradation rates owing to the mesoporosity and their improved crystallinity after calcination. Furthermore, the 3D dendrimeric architectures can be preserved after phase transformation from amorphous TiO(2) to anatase or rutile, which occurs during calcination. In addition, the spontaneous self-formation process of mesoporous TiO(2) with hierarchically 3D dendrimeric architectures from the hydrolysis and condensation reaction of titanium butoxide in methanol has been followed by in situ optical microscopy (OM), revealing the secret on the formation of hierarchically 3D dendrimeric nanostructures. Moreover, mesoporous TiO(2) nanostructures with similar hierarchically 3D dendrimeric architectures can also be obtained using other titanium alkoxides. The porosities and nanostructures of the resultant products were characterized by SEM, TEM, XRD, and N(2) adsorption-desorption measurements. The present work provides a facile and reproducible method for the synthesis of novel mesoporous TiO(2) nanoarchitectures, which in turn could herald the fabrication of more efficient photocatalysts. Copyright © 2012 Elsevier Inc. All rights reserved.

Enhanced Water Splitting by Fe2O3-TiO2-FTO Photoanode with Modified Energy Band Structure

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Eul Noh

2013-01-01

Full Text Available The effect of TiO2 layer applied to the conventional Fe2O3/FTO photoanode to improve the photoelectrochemical performance was assessed from the viewpoint of the microstructure and energy band structure. Regardless of the location of the TiO2 layer in the photoanodes, that is, Fe2O3/TiO2/FTO or TiO2/Fe2O3/FTO, high performance was obtained when α-Fe2O3 and H-TiNT/anatase-TiO2 phases existed in the constituent Fe2O3 and TiO2 layers after optimized heat treatments. The presence of the Fe2O3 nanoparticles with high uniformity in the each layer of the Fe2O3/TiO2/FTO photoanode achieved by a simple dipping process seemed to positively affect the performance improvement by modifying the energy band structure to a more favorable one for efficient electrons transfer. Our current study suggests that the application of the TiO2 interlayer, together with α-Fe2O3 nanoparticles present in the each constituent layers, could significantly contribute to the performance improvement of the conventional Fe2O3 photoanode.

Development and Application of Binary Suspensions in the Ternary System Cr2O3-TiO2-Al2O3 for S-HVOF Spraying

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Potthoff, Annegret; Kratzsch, Robert; Barbosa, Maria; Kulissa, Nick; Kunze, Oliver; Toma, Filofteia-Laura

2018-04-01

Compositions in the system Cr2O3-TiO2-Al2O3 are among the most used ceramic materials for thermally sprayed coating solutions. Cr2O3 coatings present good sliding wear resistance; Al2O3 coatings show excellent insulation behavior and TiO2 striking corrosion properties. In order to combine these properties, coatings containing more than one oxide are highly interesting. The conventional spraying process is limited to the availability of binary feedstock powders with defined compositions. The use of suspensions offers the opportunity for tailor-made chemical compositions: within the triangle of Cr2O3-TiO2-Al2O3, each mixture of oxides can be created. Criteria for the selection of raw materials as well as the relevant aspects for the development of binary suspensions in the Cr2O3-TiO2-Al2O3 system to be used as feedstock for thermal spraying are presented. This formulation of binary suspensions required the development of water-based single-oxide suspensions with suitable behavior; otherwise, the interaction between the particles while mixing could lead up to a formation of agglomerates, which affect both the stability of the spray process and the coating properties. For the validation of this formulation procedure, binary Cr2O3-TiO2 and Al2O3-TiO2 suspensions were developed and sprayed using the S-HVOF process. The binary coatings were characterized and discussed in terms of microstructure and microhardness.

Development and Application of Binary Suspensions in the Ternary System Cr2O3-TiO2-Al2O3 for S-HVOF Spraying

Science.gov (United States)

Potthoff, Annegret; Kratzsch, Robert; Barbosa, Maria; Kulissa, Nick; Kunze, Oliver; Toma, Filofteia-Laura

2018-03-01

Compositions in the system Cr2O3-TiO2-Al2O3 are among the most used ceramic materials for thermally sprayed coating solutions. Cr2O3 coatings present good sliding wear resistance; Al2O3 coatings show excellent insulation behavior and TiO2 striking corrosion properties. In order to combine these properties, coatings containing more than one oxide are highly interesting. The conventional spraying process is limited to the availability of binary feedstock powders with defined compositions. The use of suspensions offers the opportunity for tailor-made chemical compositions: within the triangle of Cr2O3-TiO2-Al2O3, each mixture of oxides can be created. Criteria for the selection of raw materials as well as the relevant aspects for the development of binary suspensions in the Cr2O3-TiO2-Al2O3 system to be used as feedstock for thermal spraying are presented. This formulation of binary suspensions required the development of water-based single-oxide suspensions with suitable behavior; otherwise, the interaction between the particles while mixing could lead up to a formation of agglomerates, which affect both the stability of the spray process and the coating properties. For the validation of this formulation procedure, binary Cr2O3-TiO2 and Al2O3-TiO2 suspensions were developed and sprayed using the S-HVOF process. The binary coatings were characterized and discussed in terms of microstructure and microhardness.

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