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Sample records for fabricated tio2 x nx

  1. Thermal behavior of TiO2-xNx nanostructured powder

    Czech Academy of Sciences Publication Activity Database

    Balek, V.; Šubrt, Jan; Irie, H.; Hashimoto, K.

    -, - (2008), No267345 ISSN 1110-662X Institutional research plan: CEZ:AV0Z40320502 Keywords : titanium-oxide photocatalysis * s-doped TiO2 Subject RIV: CH - Nuclear ; Quantum Chemistry Impact factor: 0.881, year: 2008

  2. Photo-induced hydrophilicity of TiO2-xNx thin films on PET plates

    International Nuclear Information System (INIS)

    Chou, H.-Y.; Lee, E.-K.; You, J.-W.; Yu, S.-S.

    2007-01-01

    TiO 2-x N x thin films were deposited on PET (polyethylene terephthalate) plates by sputtering a TiN target in a N 2 /O 2 plasma and without heating. X-ray photoemission spectroscopy (XPS) was used to investigate the N 1s, Ti 2p core levels and the nitrogen composition in the TiO 2-x N x films. The results indicate that Ti-O-N bonds are formed in the thin films. Two nitrogen states, substitution and interstitial nitrogen atoms, were attributed to peaks at 396 and 399 eV, respectively. It was observed that the nitrogen atoms occupy both the substitutive and interstitial sites in respective of the nitrogen content in the thin films. UV-VIS absorption spectroscopy of PET coated thin films shows a significant shift of the absorption edge to lower energy in the visible-light region. UV and visible-light irradiation are used to activate PET coated thin films for the development of hydrophilicity. The photo-induced surface wettability conversion reaction of the thin films has been investigated by means of water contact angle measurement. PET plates coated with TiO 2-x N x thin films are found to exhibit lower water contact angle than non-coated plates when the surface is illuminated with UV and visible light. The effects of nitrogen doping on photo-generated hydrophilicity of the thin films are investigated in this work

  3. Fabrication and Characteristics of Macroporous TiO2 Photocatalyst

    Directory of Open Access Journals (Sweden)

    Guiyun Yi

    2014-01-01

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

  4. Fabrication of a TiO2-P25/(TiO2-P25+TiO2 nanotubes junction for dye sensitized solar cells

    Directory of Open Access Journals (Sweden)

    Nguyen Huy Hao

    2016-08-01

    Full Text Available The dye sensitized solar cell (DSSC, which converts solar light into electric energy, is expected to be a promising renewable energy source for today's world. In this work, dye sensitized solar cells, one containing a single layer and one containing a double layer, were fabricated. In the double layer DSSC structure, the under-layer was TiO2-P25 film, and the top layer consisted of a mixture of TiO2-P25 and TiO2 nanotubes. The results indicated that the efficiency of the DSSC with the double layer structure was a significant improvement in comparison to the DSSC consisting of only a single film layer. The addition of TiO2-P25 in the top layer caused an improvement in the adsorption of dye molecules on the film rather than on the TiO2 nanotubes only. The presence of the TiO2 nanotubes together with TiO2-P25 in the top layer revealed the enhancement in harvesting the incident light and an improvement of electron transport through the film.

  5. Love Wave Ultraviolet Photodetector Fabricated on a TiO2/ST-Cut Quartz Structure

    Directory of Open Access Journals (Sweden)

    Walter Water

    2014-01-01

    Full Text Available A TiO2 thin film deposited on a 90° rotated 42°45′ ST-cut quartz substrate was applied to fabricate a Love wave ultraviolet photodetector. TiO2 thin films were grown by radio frequency magnetron sputtering. The crystalline structure and surface morphology of TiO2 thin films were examined using X-ray diffraction, scanning electron microscope, and atomic force microscope. The effect of TiO2 thin film thickness on the phase velocity, electromechanical coupling coefficient, temperature coefficient of frequency, and sensitivity of ultraviolet of devices was investigated. TiO2 thin film increases the electromechanical coupling coefficient but decreases the temperature coefficient of frequency for Love wave propagation on the 90° rotated 42°45′ ST-cut quartz. For Love wave ultraviolet photodetector application, the maximum insertion loss shift and phase shift are 2.81 dB and 3.55 degree at the 1.35-μm-thick TiO2 film.

  6. Fabrication of mesoporus TiO_2 from TiOSO_4 from leached ilmenite

    International Nuclear Information System (INIS)

    Wahyuningsih S; Ramelan AH; Rinawati L; Munifa RMI; Saputri LNMZ; Hanif QA; Pranata HP; Ismoyo YA

    2016-01-01

    The fabrication of mesoporous TiO_2 from TiOSO_4 precursor through roasted process, leaching, and homogeneous hydrolysis of ilmenite had been done. Analysis of X-ray Diffraction (XRD) showed the characteristics of ilmenite, hematite and rutile. After roasting the mineral ilmenite with the addition of Na_2S at a temperature of 800°C the XRD characterization showed peaks characteristic for hematite, TiO_2 anatase, TiO_2 rutile, Na_2SO_4, NaFeS_2, and NaFeO_2. Leaching processes of roasted ilmenite which maintained with an addition of strong acid H_2SO_4 6; 7.2; 9; 12, and 18 N were obtained TiOSO_4 filtrate. The results indicated that the more concentration of H_2SO_4 the more solubility of ilmenite, where optimum solubility was achieved when H_2SO_4 concentration was 12 N. The fabrication of mesoporous TiO_2 from TiOSO_4 was conducted with homogeneous hydrolysis method used urea and surfactant template F-127. XRD characterization results indicated the dominant peak of TiO_2 anatase. Crystallite size of 3.2 nm was obtained and the results of Scanning Electron Microscopy (SEM) showed that the presence of urea and surfactant be able to arrange porosity. (author)

  7. Fabrication of TiO2 Nanotanks Embedded in a Nanoporous Alumina Template

    Directory of Open Access Journals (Sweden)

    C. Massard

    2015-01-01

    Full Text Available The feasibility of surface nanopatterning with TiO2 nanotanks embedded in a nanoporous alumina template was investigated. Self-assembled anodized aluminium oxide (AAO template, in conjunction with sol gel process, was used to fabricate this nanocomposite object. Through hydrolysis and condensation of the titanium alkoxide, an inorganic TiO2 gel was moulded within the nanopore cavities of the alumina template. The nanocomposite object underwent two thermal treatments to stabilize and crystallize the TiO2. The morphology of the nanocomposite object was characterized by Field Emission Scanning Electron Microscopy (FESEM. The TiO2 nanotanks obtained have cylindrical shapes and are approximately 69 nm in diameter with a tank-to-tank distance of 26 nm. X-ray diffraction analyses performed by Transmission Electron Microscopy (TEM with selected area electron diffraction (SAED were used to investigate the TiO2 structure. The optical properties were studied using UV-Vis spectroscopy.

  8. 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

  9. 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)

  10. 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

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

    Science.gov (United States)

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

    2017-05-01

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

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

    International Nuclear Information System (INIS)

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

    2012-01-01

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

  13. 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.

  14. Fabrication and characterization of TiO2-epoxy nanocomposite

    International Nuclear Information System (INIS)

    Chatterjee, Amit; Islam, Muhammad S.

    2008-01-01

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

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

    International Nuclear Information System (INIS)

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

    2008-01-01

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

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  17. Electrical response of electron selective atomic layer deposited TiO2‑x heterocontacts on crystalline silicon substrates

    Science.gov (United States)

    Ahiboz, Doğuşcan; Nasser, Hisham; Aygün, Ezgi; Bek, Alpan; Turan, Raşit

    2018-04-01

    Integration of oxygen deficient sub-stoichiometric titanium dioxide (TiO2‑x) thin films as the electron transporting-hole blocking layer in solar cell designs are expected to reduce fabrication costs by eliminating high temperature processes while maintaining high conversion efficiencies. In this paper, we conducted a study to reveal the electrical properties of TiO2‑x thin films grown on crystalline silicon (c-Si) substrates by atomic layer deposition (ALD) technique. Effect of ALD substrate temperature, post deposition annealing, and doping type of the c-Si substrate on the interface states and TiO2‑x bulk properties were extracted by performing admittance (C-V, G-V) and current-voltage (J-V) measurements. Moreover, the asymmetry in C-V and J-V measurements between the p-n type and n-n TiO2‑x-c-Si heterojunction types were examined and the electron transport selectivity of TiO2‑x was revealed.

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

    Science.gov (United States)

    Zhang, Yu; Gu, Jian; Zhang, Mengqi

    2018-06-01

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

  19. Fabrication of TiO_2 nanorod assembly grafted rGO (rGO@TiO_2-NR) hybridized flake-like photocatalyst

    International Nuclear Information System (INIS)

    Lv, Kangle; Fang, Shun; Si, Lingling; Xia, Yang; Ho, Wingkei; Li, Mei

    2017-01-01

    Highlights: • TiO_2 nanorod assembly grafted with GO hybrid was successfully fabricated. • TiO_2 nanorods can reduce the aggregation of TiO_2 nanoparticles on graphene. • This unique structure facilitates the injection of electron from TiO_2 to graphene. - Abstract: To efficiently separate the photo-generated electron–hole pairs of TiO_2 hybrid, anatase TiO_2 nanorod assembly grafted reduced graphene oxides (rGO@TiO_2-NR) hybrid was successfully fabricated using potassium titanium oxalate (PTO) and graphene oxides (GO) as starting materials and diethylene glycol (DEG) as reductant. The effect of GO content on the structure and photocatalytic activity of rGO@TiO_2-NR composite was systematically studied. Results show that, in the absence of GO, only TiO_2 microsphere assembly is obtained from TiO_2 nanorods. The presence of GO results in the formation of a flake-like TiO_2-nanorod-assembled grafted rGO hybrid. The photocatalytic activity of rGO@TiO_2-NR composite increases first and then decreases with increase in the amount of GO from 0 wt.% to 10 wt.%. The hybridized S4 sample prepared with 4 wt.% GO possesses the highest photocatalytic activity with a constant rate of 0.039 min"−"1 in the photocataytic degradation of Brilliant X-3B dye (X3B); this sample was enhanced more than three times when compared with pure TiO_2 sample (0.012 min"−"1). The enhanced photocatalytic activity of the rGO@TiO_2-NR hybrid was attributed to the strong interaction between TiO_2 nanorods and rGO. The unique hierarchical structure of 1D nanorod assembly TiO_2–rGO flakes facilitates the injection and transfer of photo-generated electrons from TiO_2 to graphene, thus retarding the recombination of electron–hole pairs and enhancing the photocatalytic activity. The enlarged BET surface areas, not only increasing the number of active sites, but also facilitating the adsorption of the dye, and improved light-harvesting ability also contribute to the enhanced photoreactivity

  20. The design, fabrication, and photocatalytic utility of nanostructured semiconductors: focus on TiO2-based nanostructures

    Directory of Open Access Journals (Sweden)

    Arghya Narayan Banerjee

    2011-02-01

    Full Text Available Arghya Narayan BanerjeeSchool of Mechanical Engineering, Yeungnam University, Gyeongsan, South KoreaAbstract: Recent advances in basic fabrication techniques of TiO2-based nanomaterials such as nanoparticles, nanowires, nanoplatelets, and both physical- and solution-based techniques have been adopted by various research groups around the world. Our research focus has been mainly on various deposition parameters used for fabricating nanostructured materials, including TiO2-organic/inorganic nanocomposite materials. Technically, TiO2 shows relatively high reactivity under ultraviolet light, the energy of which exceeds the band gap of TiO2. The development of photocatalysts exhibiting high reactivity under visible light allows the main part of the solar spectrum to be used. Visible light-activated TiO2 could be prepared by doping or sensitizing. As far as doping of TiO2 is concerned, in obtaining tailored material with improved properties, metal and nonmetal doping has been performed in the context of improved photoactivity. Nonmetal doping seems to be more promising than metal doping. TiO2 represents an effective photocatalyst for water and air purification and for self-cleaning surfaces. Additionally, it can be used as an antibacterial agent because of its strong oxidation activity and superhydrophilicity. Therefore, applications of TiO2 in terms of photocatalytic activities are discussed here. The basic mechanisms of the photoactivities of TiO2 and nanostructures are considered alongside band structure engineering and surface modification in nanostructured TiO2 in the context of doping. The article reviews the basic structural, optical, and electrical properties of TiO2, followed by detailed fabrication techniques of 0-, 1-, and quasi-2-dimensional TiO2 nanomaterials. Applications and future directions of nanostructured TiO2 are considered in the context of various photoinduced phenomena such as hydrogen production, electricity generation via

  1. Fabrication of TiO2-Reduced Graphene Oxide Nanorod Composition Spreads Using Combinatorial Hydrothermal Synthesis and Their Photocatalytic and Photoelectrochemical Applications.

    Science.gov (United States)

    Lu, Wen-Chung; Tseng, Li-Chun; Chang, Kao-Shuo

    2017-09-11

    This study is the first to employ combinatorial hydrothermal synthesis and facile spin-coating technology to fabricate TiO 2 -reduced graphene oxide (rGO) nanorod composition spreads. The features of this study are (1) the development of a self-designed spin-coating wedge, (2) the systemic investigation of the structure-property relationship of the system, (3) the high-throughput screening of the optimal ratio from a wide range of compositions for photocatalytic and photoelectrochemical (PEC) applications, and (4) the effective coupling between the density gradient TiO 2 nanorod array and the thickness gradient rGO. The formation of rGO in the fabricated TiO 2 -rGO sample was monitored through Fourier transform infrared spectrometry. Transmission electron microscopy images also suggested that the TiO 2 nanorod surfaces were covered with a thin layer of amorphous rGO. The rutile TiO 2 plane evolution along the composition variation was verified through X-ray diffraction. 7% TiO 2 -93% rGO on the nanorod composition spread exhibited the most promising photocatalytic ability; the corresponding photodegradation kinetics, denoted by the photodegradation rate constant (k), was determined to be approximately 12.7 × 10 -3 min -1 . The excellent performance was attributed to the effective coupling between the TiO 2 and rGO, which improved the charge carrier transport, thus inhibiting electron-hole pair recombination. A cycling test implied that 7% TiO 2 -93% rGO is a reliable photocatalyst. A photoluminescence spectroscopy study also supported the superior photocatalytic ability of the sample, which was attributed to its markedly poorer recombination behavior. In addition, without further treatment, the sample exhibited excellent PEC stability; the photocurrent density was more than three times higher than that exhibited by the density gradient TiO 2 nanorods.

  2. The design, fabrication, and photocatalytic utility of nanostructured semiconductors: focus on TiO2-based nanostructures

    Science.gov (United States)

    Banerjee, Arghya Narayan

    2011-01-01

    Recent advances in basic fabrication techniques of TiO2-based nanomaterials such as nanoparticles, nanowires, nanoplatelets, and both physical- and solution-based techniques have been adopted by various research groups around the world. Our research focus has been mainly on various deposition parameters used for fabricating nanostructured materials, including TiO2-organic/inorganic nanocomposite materials. Technically, TiO2 shows relatively high reactivity under ultraviolet light, the energy of which exceeds the band gap of TiO2. The development of photocatalysts exhibiting high reactivity under visible light allows the main part of the solar spectrum to be used. Visible light-activated TiO2 could be prepared by doping or sensitizing. As far as doping of TiO2 is concerned, in obtaining tailored material with improved properties, metal and nonmetal doping has been performed in the context of improved photoactivity. Nonmetal doping seems to be more promising than metal doping. TiO2 represents an effective photocatalyst for water and air purification and for self-cleaning surfaces. Additionally, it can be used as an antibacterial agent because of its strong oxidation activity and superhydrophilicity. Therefore, applications of TiO2 in terms of photocatalytic activities are discussed here. The basic mechanisms of the photoactivities of TiO2 and nanostructures are considered alongside band structure engineering and surface modification in nanostructured TiO2 in the context of doping. The article reviews the basic structural, optical, and electrical properties of TiO2, followed by detailed fabrication techniques of 0-, 1-, and quasi-2-dimensional TiO2 nanomaterials. Applications and future directions of nanostructured TiO2 are considered in the context of various photoinduced phenomena such as hydrogen production, electricity generation via dye-sensitized solar cells, photokilling and self-cleaning effect, photo-oxidation of organic pollutant, wastewater management, and

  3. Synthesis variables effect on TiO2/polyester fabrics photoactivity and stability

    Directory of Open Access Journals (Sweden)

    Camilo Castro

    2016-12-01

    Full Text Available TiO2-SiO2 coatings on fabric samples were obtained by immersion of 9cm2 of commercial polyester in a TiO2-SiO2 suspension. This suspension was prepared by adding TiO2 P25 to a silica matrix obtained from the hydrolysis of tetraethyl orthosilicate (TEOS. The aim of this work was to study the relationship between the immersion time of the fabric on the photocatalytic activity and stability of the coating against several cycles of use and washing. Obtained samples were characterized by scanning electron microscopy (SEM, energy dispersive spectroscopy (EDS and infrared spectroscopy (FTIR-ATR. Evaluation of modified fabrics was performed by self-disinfection tests under 250W/m2 of simulated sunlight using E. coli as model bacteria. In general, all modified fabrics (except that obtained at 2h immersion time inactivated bacteria in less than 120min and its regrowth was prevented for at least 24h after the disinfection tests. It was determined that low immersion time (3-4h lead to active and stable fabrics to 3 cycles of use and washing, whereas higher immersion times (12h lead to more active but unstable fabrics.

  4. TiO2 Nanoparticles as a Soft X-ray Molecular Probe

    Energy Technology Data Exchange (ETDEWEB)

    Larabell, Carolyn; Ashcroft, Jared M.; Gu, Weiwei; Zhang, Tierui; Hughes, Steven M.; Hartman, Keith B.; Hofmann, Cristina; Kanaras, Antonios G.; Kilcoyne, David A.; Le Gros, Mark; Yin, Yadong; Alivisatos, A. Paul; Larabell, Carolyn A.

    2007-06-30

    With the emergence of soft x-ray techniques for imaging cells, there is a pressing need to develop protein localization probes that can be unambiguously identified within the region of x-ray spectrum used for imaging. TiO2 nanocrystal colloids, which have a strong absorption cross-section within the "water-window" region of x-rays, areideally suited as soft x-ray microscopy probes. To demonstrate their efficacy, TiO2-streptavidin nanoconjugates were prepared and subsequently labeled microtubules polymerized from biotinylated tubulin. The microtubules were imaged using scanning transmission x-ray microscopy (STXM), and the TiO2 nanoparticle tags were specifically identified using x-ray absorption near edge spectroscopy (XANES). These experiments demonstrate that TiO2 nanoparticles are potential probes for protein localization analyses using soft x-ray microscopy.

  5. Tuning the resistive switching properties of TiO2-x films

    Science.gov (United States)

    Ghenzi, N.; Rozenberg, M. J.; Llopis, R.; Levy, P.; Hueso, L. E.; Stoliar, P.

    2015-03-01

    We study the electrical characteristics of TiO2-x-based resistive switching devices fabricated with different oxygen/argon flow ratio during the oxide thin film sputtering deposition. Upon minute changes in this fabrication parameter, three qualitatively different device characteristics were accessed in the same system, namely, standard bipolar resistive switching, electroforming-free devices, and devices with multi-step breakdown. We propose that small variations in the oxygen/ argon flow ratio result in relevant changes of the oxygen vacancy concentration, which is the key parameter determining the resistive switching behavior. The coexistence of percolative or non-percolative conductive filaments is also discussed. Finally, the hypothesis is verified by means of the temperature dependence of the devices in low resistance state.

  6. Surface Coatings of TiO2 Nanoparticles onto the Designed Fabrics for Enhanced Self-Cleaning Properties

    Directory of Open Access Journals (Sweden)

    Mudassar Abbas

    2018-01-01

    Full Text Available Herein, the hydrophobic and self-cleaning properties of three different fabric surfaces have been evaluated after applying titanium dioxide (TiO2 nanofinishes. The nanoparticles were prepared by sol-gel techniques and were characterized by using X-ray diffraction (XRD, scanning electron microscopy (SEM and dynamic light scattering (DLS methods. The ultra-refined particles were applied over three different fabric substrates having similar weave of Z-twill (3/1. The yarns of 100% polyester, blend of viscose with mod-acrylic and high performance polyethylene containing 16 yarn count (Ne and 31.496 and 15.748 ends/cm and picks/cm, respectively, were used for required fabric preparation. The different fabric structures were applied with self-cleaning finish of TiO2 nanoparticles prepared in our laboratory and the results were compared with commercially available finish Rucoguard AFR. The static contact angles, UV-protection factor, air permeability and hydrophobic activity of nanofinished fabric helped in evaluating their breathability and self-cleaning properties.

  7. Bactericidal activity under UV and visible light of cotton fabrics coated with anthraquinone-sensitized TiO2

    KAUST Repository

    Rahal, Raed; Le Bé chec, Mickaë l; Guyoneaud, Ré my; Pigot, Thierry; Paolacci, H.; Lacombe, Sylvie M.

    2013-01-01

    . The experimental method allowed the accurate quantification of bacteria survival on photoactive surfaces and films under UVA and UV-free visible irradiation. Cotton fabrics coated with TiO2, anthraquinone or anthraquinone-sensitized TiO2 display a significant

  8. Fabricating TiO2 nanocolloids by electric spark discharge method at normal temperature and pressure

    Science.gov (United States)

    Tseng, Kuo-Hsiung; Chang, Chaur-Yang; Chung, Meng-Yun; Cheng, Ting-Shou

    2017-11-01

    In this study, TiO2 nanocolloids were successfully fabricated in deionized water without using suspending agents through using the electric spark discharge method at room temperature and under normal atmospheric pressure. This method was exceptional because it did not create nanoparticle dispersion and the produced colloids contained no derivatives. The proposed method requires only traditional electrical discharge machines (EDMs), self-made magnetic stirrers, and Ti wires (purity, 99.99%). The EDM pulse on time (T on) and pulse off time (T off) were respectively set at 50 and 100 μs, 100 and 100 μs, 150 and 100 μs, and 200 and 100 μs to produce four types of TiO2 nanocolloids. Zetasizer analysis of the nanocolloids showed that a decrease in T on increased the suspension stability, but there were no significant correlations between T on and particle size. Colloids produced from the four production configurations showed a minimum particle size between 29.39 and 52.85 nm and a zeta-potential between -51.2 and -46.8 mV, confirming that the method introduced in this study can be used to produce TiO2 nanocolloids with excellent suspension stability. Scanning electron microscopy with energy dispersive spectroscopy also indicated that the TiO2 colloids did not contain elements other than Ti and oxygen.

  9. Fabricating TiO2 nanocolloids by electric spark discharge method at normal temperature and pressure.

    Science.gov (United States)

    Tseng, Kuo-Hsiung; Chang, Chaur-Yang; Chung, Meng-Yun; Cheng, Ting-Shou

    2017-11-17

    In this study, TiO 2 nanocolloids were successfully fabricated in deionized water without using suspending agents through using the electric spark discharge method at room temperature and under normal atmospheric pressure. This method was exceptional because it did not create nanoparticle dispersion and the produced colloids contained no derivatives. The proposed method requires only traditional electrical discharge machines (EDMs), self-made magnetic stirrers, and Ti wires (purity, 99.99%). The EDM pulse on time (T on ) and pulse off time (T off ) were respectively set at 50 and 100 μs, 100 and 100 μs, 150 and 100 μs, and 200 and 100 μs to produce four types of TiO 2 nanocolloids. Zetasizer analysis of the nanocolloids showed that a decrease in T on increased the suspension stability, but there were no significant correlations between T on and particle size. Colloids produced from the four production configurations showed a minimum particle size between 29.39 and 52.85 nm and a zeta-potential between -51.2 and -46.8 mV, confirming that the method introduced in this study can be used to produce TiO 2 nanocolloids with excellent suspension stability. Scanning electron microscopy with energy dispersive spectroscopy also indicated that the TiO 2 colloids did not contain elements other than Ti and oxygen.

  10. Bactericidal activity under UV and visible light of cotton fabrics coated with anthraquinone-sensitized TiO2

    KAUST Repository

    Rahal, Raed

    2013-06-01

    This study describes a method derived from ISO/TC 206/SC specifications to assess the bactericidal activity against a bacterial strain, Pseudomonas fluorescens, of various photocatalytic fabrics, under UVA and filtered visible light. The experimental method allowed the accurate quantification of bacteria survival on photoactive surfaces and films under UVA and UV-free visible irradiation. Cotton fabrics coated with TiO2, anthraquinone or anthraquinone-sensitized TiO2 display a significant bactericidal efficiency. TiO2-coated fabrics are very efficient against P. fluorescens after 4 h UVA irradiation (bacteria survival below the detection limit). Under UVA-free visible light, anthraquinone-sensitized TiO2 coated fabrics induced a significant bactericidal activity after 2 h irradiation, while anthraquinone alone-coated fabrics were not as efficient and TiO2 coated fabrics were almost inefficient. These results show that although exhibiting a weak n-π* band in the 350-420 nm range, anthraquinone is a good candidate as an efficient visible light photosensitizer. A synergy effect between anthraquinone and TiO2 was demonstrated. A possible reaction mechanism, involving a synergy effect for singlet oxygen formation with anthraquinone-sensitized TiO2 is proposed to account for these results. © 2012 Elsevier B.V. All rights reserved.

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

    Directory of Open Access Journals (Sweden)

    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.

  12. Fabrication of predominantly Mn4+ -doped TiO2 nanoparticles under equilibrium conditions and their application as visible-light photocatalyts.

    Science.gov (United States)

    Wang, Lijie; Fan, Jiajie; Cao, Zetan; Zheng, Yichao; Yao, Zhiqiang; Shao, Guosheng; Hu, Junhua

    2014-07-01

    The chemical state of a transition-metal dopant in TiO(2) can intrinsically determine the performance of the doped material in applications such as photocatalysis and photovoltaics. In this study, manganese-doped TiO2 is fabricated by a near-equilibrium process, in which the TiO(2) precursor powder precipitates from a hydrothermally obtained transparent mother solution. The doping level and subsequent thermal treatment influence the morphology and crystallization of the TiO(2) samples. FTIR spectroscopy and X-ray photoelectron spectroscopy analyses indicate that the manganese dopant is substitutionally incorporated by replacing Ti(4+) cations. The absorption band edge can be gradually shifted to 1.8 eV by increasing the nominal manganese content to 10 at %. Manganese atoms doped into the titanium lattice are associated with the dominant 4+ valence oxidation state, which introduces two curved, intermediate bands within the band gap and results in a significant enhancement in photoabsorption and the quantity of photogenerated hydroxyl radicals. Additionally, the high photocatalytic performance of manganese-doped TiO(2) is also attributed to the low oxygen content, owing to the equilibrium fabrication conditions. This work provides an important strategy to control the chemical and defect states of dopants by using an equilibrium fabrication process. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Fabrication of TiO_2-modified polytetrafluoroethylene ultrafiltration membranes via plasma-enhanced surface graft pretreatment

    International Nuclear Information System (INIS)

    Qian, Yingjia; Chi, Lina; Zhou, Weili; Yu, Zhenjiang; Zhang, Zhongzhi; Zhang, Zhenjia; Jiang, Zheng

    2016-01-01

    Graphical abstract: - Highlights: • Multifunctional TiO_2/PAA/PTFE ultrafiltration membrane was fabricated via tight coating of TiO_2 functional layer onto the plasma-assisted graft of PAA on PTFE. • The high water flux rate, remarkable enhanced ultrafiltration performance and excellent self-cleaning ability were demonstrated. • The formation of COO−Ti bidentate coordination between TiO_2 and PAA was responsible for the successful coating. - Abstract: Surface hydrophilic modification of polymer ultrafiltration membrane using metal oxide represents an effective yet highly challenging solution to improve water flux and antifouling performance. Via plasma-enhanced graft of poly acryl acid (PAA) prior to coating TiO_2, we successfully fixed TiO_2 functional thin layer on super hydrophobic polytetrafluoroethylene (PTFE) ultrafiltration (UF) membranes. The characterization results evidenced TiO_2 attached on the PTFE-based UF membranes through the chelating bidentate coordination between surface-grafted carboxyl group and Ti"4"+. The TiO_2 surface modification may greatly reduce the water contact angle from 115.8° of the PTFE membrane to 35.0° without degradation in 30-day continuous filtration operations. The novel TiO_2/PAA/PTFE membranes also exhibited excellent antifouling and self-cleaning performance due to the intrinsic hydrophilicity and photocatalysis properties of TiO_2, which was further confirmed by the photo-degradation of MB under Xe lamp irradiation.

  14. Cotton fabric finishing with TiO2/SiO2 composite hydrosol based on ionic cross-linking method

    International Nuclear Information System (INIS)

    Xu, Z.J.; Tian, Y.L.; Liu, H.L.; Du, Z.Q.

    2015-01-01

    Highlights: • We studied the cotton finishing with TiO 2 /SiO 2 based on ionic cross-linking method. • The samples treated with CHTAC had lower value of whiteness. • The samples treated with BTCA achieved higher crease recovery angle and lower tensile strength. • The ionic cross-linking treatment (CHTAC + BTCA + TiO 2 /SiO 2 ) was better than with TiO 2 /SiO 2 sol alone. - Abstract: Cotton fabric was successfully modified by 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CHTAC), 1,2,3,4-butanetetracarboxylic acid (BTCA) and TiO 2 /SiO 2 sol. Self-cleaning characteristic was investigated using a Color Measuring and Matching System with 6 h sunlight irradiation. And the stability of TiO 2 /SiO 2 coatings was explored by measuring the washing fastness and wrinkle resistance of treated cotton samples. In addition, whiteness index, crease recovery angle and tensile strength retention (%) of treated samples were evaluated. Moreover, the morphology, structure change and crystallinity of samples were observed by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD), respectively. The results revealed that the samples treated with CHTAC had lower value of whiteness index as compared with original cotton fabric. It was also found that samples treated with BTCA achieved higher crease recovery angle and lower tensile strength. Moreover, the treatment of CHTAC and BTCA had adverse effect on the crystallinity of cotton samples, as treated samples had lower crystallinity in comparison with raw cotton fabrics. Nevertheless, the stability of self-cleaning coatings was better for samples treated with ionic cross-linking treatment (CHTAC + BTCA + TiO 2 /SiO 2 ) than samples treated with TiO 2 /SiO 2 sol alone. Furthermore, compared with original samples the UV-blocking property of ionic cross-linking treated samples was obviously enhanced

  15. Digital selective fabrication of micro/nano-composite structured TiO2 nanorod arrays by laser direct writing

    Science.gov (United States)

    Jiang, Wei; He, Xiaoning; Liu, Hongzhong; Yin, Lei; Shi, Yongsheng; Ding, Yucheng

    2014-11-01

    In this article, we report on the digital selective fabrication of micro/nano-composite structured TiO2 nanorod arrays by laser direct writing. The pattern of TiO2 nanorod arrays can be easily designed and fabricated by laser scanning technology integrated with a computer-aided design system, which allows a high degree of freedom corresponding to the various pattern design demands. The approach basically involves the hydrothermal growth of TiO2 nanorod arrays on a transparent conductive substrate, the micropattern of TiO2 nanorod arrays and surface fluorination treatment. With these micro/nano-composite TiO2 nanorod array based films, we have demonstrated superhydrophilic patterned TiO2 nanorod arrays with rapid water spreading ability and superhydrophobic patterned TiO2 nanorod arrays with an excellent droplet bouncing effect and a good self-cleaning performance. The dynamic behaviours of the water droplets observed on the patterned TiO2 nanorod arrays were demonstrated by experiments and simulated by a finite element method. The approaches we will show are expected to provide potential applications in fields such as self-cleaning, surface protection, anticrawling and microfluidic manipulation.

  16. Effect Of Ti Powder Addition On The Fabrication Of TiO2 Nanopowders

    Directory of Open Access Journals (Sweden)

    Raihanuzzaman R.M.

    2015-06-01

    Full Text Available Sintered samples of Ti added TiO2 nanopowders were fabricated by combined application of magnetic pulsed compaction (MPC and sintering. The effect of Ti nano powder on density, shrinkage and hardness of the samples were investigated as part of the study. The optimum processing conditions were found to be around 0.5 GPa MPC pressure and 1450°C sintering temperature, illustrating maximum density, hardness and minimum shrinkage. High pressure compaction using MPC was found to enhance density with increasing MPC pressure up to 0.9 GPa, and significantly reduce the total shrinkage (about 16% in this case in the sintered bulks compared to other general processes (about 18%. While sintered samples blended with micro Ti showed presence of microstructural cracks, the samples with 1-2% nano Ti had less or no cracks on them. Overall, the inclusion of nano Ti indicated improvement in mechanical properties of TiO2 nanopowders sintered preforms as opposed to micro Ti-added TiO2.

  17. Low temperature fabrication of V-doped TiO2 nanoparticles, structure and photocatalytic studies

    International Nuclear Information System (INIS)

    Liu Baoshun; Wang Xuelai; Cai Guofa; Wen Liping; Song Yanbao; Zhao Xiujian

    2009-01-01

    V-doped TiO 2 nanoparticles were synthesized at low temperature and characterized by X-ray diffraction (XRD), Raman spectroscopy (RS), transmission electron microscopy (TEM), Brunauer-Emmet-Teller (BET), X-ray photoelectron spectroscopy (XPS), UV-vis spectroscopy, and photoluminescence (PL) spectroscopy, respectively. It is found the nanoparticle shape changed from needle, to short stick and then to cubic with the increase of doped V concentration, which was also accompanied by the improvement of crystallinity. The specific surface area (S BET ) decreased with increasing V content. It is confirmed that V ions can be doped in TiO 2 by substituting Ti 4+ ions, which suppressed the CB → VB and surface recombination of photoinduced electrons and holes, and a relation was found between the PL spectra and the UV photocatalytic activity. There was an optimum V content for the V-doped TiO 2 to present the best UV-light induced photoactivity, but they were visible-inactive. At last, the effect of the doping V as trapping centers on photocatalysis was investigated in detail, and used to explain the difference between the photocatalysis under the illumination of UV light and visible light.

  18. Solvothermal fabrication of activated semi-coke supported TiO2-rGO nanocomposite photocatalysts and application for NO removal under visible light

    Science.gov (United States)

    Yang, Weiwei; Li, Chunhu; Wang, Liang; Sun, ShengNan; Yan, Xin

    2015-10-01

    The photocatalysts of activated semi-coke supported TiO2-rGO nanocomposite (TiO2-rGO/ASC) with different contents of reduced graphene oxide were fabricated by one-step solvothermal method for NO removal under visible light irradiation. It was confirmed that 8% content of reduced graphene oxide presented the best NO photooxidation performance under visible light irradiation at 70 °C with 350-400 mg/m3 NO,5% O2 and 5% relative humidity. The reasons for improved activity were discussed, alloyed with the mechanism of producing CO. Detailed structural information of TiO2-rGO/ASC photocatalysts was characterized by scanning electron microscope (SEM), energy dispersive X-ray Spectroscopy (EDX), X-ray diffraction analysis (XRD), UV-Vis diffuse reflectance spectra (UV-Vis DRS) and photoluminescence (PL), which indicated that the introduction of rGO was responsible for well dispersion, smaller crystalline size, red shift of absorption band and suppressing quick photo-induced charges recombination of TiO2-rGO/ASC photocatalysts. Optimization of operational parameters with 70 °C, 8% O2 and 8% relative humidity were also obtained. Deactivation of TiO2-rGO/ASC photocatalysts for NO removal was investigated by Fourier-transform infrared (FTIR) analysis. Regeneration experiments showed that thermal vapor regeneration would be optimal method owing to excellent regenerative capacity and inexpensive procedure.

  19. The Effect of Titanium Dioxide (TiO2) Nanoparticles on Hydroxyapatite (HA)/TiO2 Composite Coating Fabricated by Electrophoretic Deposition (EPD)

    Science.gov (United States)

    Amirnejad, M.; Afshar, A.; Salehi, S.

    2018-05-01

    Composite coatings of Hydroxyapatite (HA) with ceramics, polymers and metals are used to modify the surface structure of implants. In this research, HA/TiO2 composite coating was fabricated by electrophoretic deposition (EPD) on 316 stainless steel substrate. HA/TiO2 composite coatings with 5, 10 and 20 wt.% of TiO2, deposited at 40 V and 90 s as an optimum condition. The samples coated at this condition led to an adherent, continuous and crack-free coating. The influence of TiO2 content was studied by performing different characterization methods such as scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), corrosion resistance in simulated body fluid (SBF), coating's dissolution rate in physiological solution and bond strength to the substrate. The results showed that the higher amount of TiO2 in the composite coating led to increase in bond strength of coating to stainless steel substrate from 3 MPa for HA coating to 5.5 MPa for HA-20 wt.% TiO2 composite coating. In addition, it caused to reduction of corrosion current density of samples in the SBF solution from 18.92 μA/cm2 for HA coating to 6.35 μA/cm2 for HA-20 wt.% TiO2 composite coating.

  20. The Effect of Titanium Dioxide (TiO2) Nanoparticles on Hydroxyapatite (HA)/TiO2 Composite Coating Fabricated by Electrophoretic Deposition (EPD)

    Science.gov (United States)

    Amirnejad, M.; Afshar, A.; Salehi, S.

    2018-04-01

    Composite coatings of Hydroxyapatite (HA) with ceramics, polymers and metals are used to modify the surface structure of implants. In this research, HA/TiO2 composite coating was fabricated by electrophoretic deposition (EPD) on 316 stainless steel substrate. HA/TiO2 composite coatings with 5, 10 and 20 wt.% of TiO2, deposited at 40 V and 90 s as an optimum condition. The samples coated at this condition led to an adherent, continuous and crack-free coating. The influence of TiO2 content was studied by performing different characterization methods such as scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), corrosion resistance in simulated body fluid (SBF), coating's dissolution rate in physiological solution and bond strength to the substrate. The results showed that the higher amount of TiO2 in the composite coating led to increase in bond strength of coating to stainless steel substrate from 3 MPa for HA coating to 5.5 MPa for HA-20 wt.% TiO2 composite coating. In addition, it caused to reduction of corrosion current density of samples in the SBF solution from 18.92 μA/cm2 for HA coating to 6.35 μA/cm2 for HA-20 wt.% TiO2 composite coating.

  1. Fabrication of TiO2 nanorod assembly grafted rGO (rGO@TiO2-NR) hybridized flake-like photocatalyst

    Science.gov (United States)

    Lv, Kangle; Fang, Shun; Si, Lingling; Xia, Yang; Ho, Wingkei; Li, Mei

    2017-01-01

    To efficiently separate the photo-generated electron-hole pairs of TiO2 hybrid, anatase TiO2 nanorod assembly grafted reduced graphene oxides (rGO@TiO2-NR) hybrid was successfully fabricated using potassium titanium oxalate (PTO) and graphene oxides (GO) as starting materials and diethylene glycol (DEG) as reductant. The effect of GO content on the structure and photocatalytic activity of rGO@TiO2-NR composite was systematically studied. Results show that, in the absence of GO, only TiO2 microsphere assembly is obtained from TiO2 nanorods. The presence of GO results in the formation of a flake-like TiO2-nanorod-assembled grafted rGO hybrid. The photocatalytic activity of rGO@TiO2-NR composite increases first and then decreases with increase in the amount of GO from 0 wt.% to 10 wt.%. The hybridized S4 sample prepared with 4 wt.% GO possesses the highest photocatalytic activity with a constant rate of 0.039 min-1 in the photocataytic degradation of Brilliant X-3B dye (X3B); this sample was enhanced more than three times when compared with pure TiO2 sample (0.012 min-1). The enhanced photocatalytic activity of the rGO@TiO2-NR hybrid was attributed to the strong interaction between TiO2 nanorods and rGO. The unique hierarchical structure of 1D nanorod assembly TiO2-rGO flakes facilitates the injection and transfer of photo-generated electrons from TiO2 to graphene, thus retarding the recombination of electron-hole pairs and enhancing the photocatalytic activity. The enlarged BET surface areas, not only increasing the number of active sites, but also facilitating the adsorption of the dye, and improved light-harvesting ability also contribute to the enhanced photoreactivity of rGO@TiO2-NR hybrid.

  2. Rapid fabrication of mesoporous TiO2 thin films by pulsed fibre laser for dye sensitized solar cells

    Science.gov (United States)

    Hadi, Aseel; Alhabradi, Mansour; Chen, Qian; Liu, Hong; Guo, Wei; Curioni, Michele; Cernik, Robert; Liu, Zhu

    2018-01-01

    In this paper we demonstrate for the first time that a fibre laser with a wavelength of 1070 nm and a pulse width of milliseconds can be applied to generate mesoporous nanocrystalline (nc) TiO2 thin films on ITO coated glass in ambient atmosphere, by complete vaporisation of organic binder and inter-connection of TiO2 nanoparticles, without thermally damaging the ITO layer and the glass substrate. The fabrication of the mesoporous TiO2 thin films was achieved by stationary laser beam irradiation of 1 min. The dye sensitized solar cell (DSSC) with the laser-sintered TiO2 photoanode reached higher power conversion efficiency (PCE) of 3.20% for the TiO2 film thickness of 6 μm compared with 2.99% for the furnace-sintered. Electrochemical impedance spectroscopy studies revealed that the laser sintering under the optimised condition effectively decreased charge transfer resistance and increased electron lifetime of the TiO2 thin films. The use of the fibre laser with over 40% wall-plug efficiency offers an economically-feasible, industrial viable solution to the major challenge of rapid fabrication of large scale, mass production of mesoporous metal oxide thin film based solar energy systems, potentially for perovskite and monolithic tandem solar cells, in the future.

  3. What can we learn from the decay of $ N_X(1625)$ in molecule picture?

    OpenAIRE

    Liu, Xiang; Zhang, Bo

    2007-01-01

    Considering two molecular state assumptions, i.e. S-wave $\\bar{\\Lambda}-K^-$ and S-wave $\\bar{\\Sigma}^0-K^-$ molecular states, we study the possible decays of $\\bar N_X(1625)$ that include $\\bar N_X(1625)\\to K^{-}\\bar{\\Lambda}, \\pi^{0}\\bar{p}, \\eta\\bar{p}, \\pi^{-}\\bar{n}$. Our results indicate: (1) if $\\bar N_{X}(1625)$ is $\\bar{\\Lambda}-K^-$ molecular state, $K^{-}\\bar{\\Lambda}$ is the main decay modes of $\\bar N_{X}(1625)$, and the branching ratios of the rest decay modes are tiny; (2) if $...

  4. Experimental and theoretical studies on X-ray induced secondary electron yields in Ti and TiO2

    International Nuclear Information System (INIS)

    Iyasu, Takeshi; Tamura, Keiji; Shimizu, Ryuichi; Vlaicu, Mihai Aurel; Yoshikawa, Hideki

    2006-01-01

    Generation of X-ray induced secondary electrons in Ti and TiO 2 was studied from both experimental and theoretical approaches, using X-ray photoelectron spectroscopy (XPS) attached to a synchrotron radiation facility and Monte Carlo simulation, respectively. The experiment revealed that the yields of secondary electrons induced by X-rays (electrons/photon) at photon energies to 4950 and 5000eV for Ti and TiO 2 are δ Ti (4950eV)=0.002 and δ Ti (5000eV)=0.014 while those for TiO 2 are δ TiO 2 (4950eV)=0.003 and δ TiO 2 (5000eV)=0.018. A novel approach to obtain the escape depth of secondary electrons has been proposed and applied to Ti and TiO 2 . The approach agreed very well with the experimental data reported so far. The Monte Carlo simulation predicted; δ Ti * (4950eV)=0.002 and δ Ti * (5000eV)=0.011 while δ TiO 2 * (4950eV)=0.003 and δ TiO 2 * (5000eV)=0.015. An experimental examination on the contribution of X-ray induced secondary electrons to photocatalysis in TiO 2 has also been proposed

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

    Science.gov (United States)

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

    2018-02-01

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

  6. Facile fabrication of Si-doped TiO2 nanotubes photoanode for enhanced photoelectrochemical hydrogen generation

    Science.gov (United States)

    Dong, Zhenbiao; Ding, Dongyan; Li, Ting; Ning, Congqin

    2018-04-01

    Photoelectrochemical (PEC) water splitting based doping modified one dimensional (1D) titanium dioxide (TiO2) nanostructures provide an efficient method for hydrogen generation. Here we first successfully fabricated 1D Si-doped TiO2 (Ti-Si-O) nanotube arrays through anodizing Ti-Si alloys with different Si amount, and reported the PEC properties for water splitting. The Ti-Si-O nanotube arrays fabricated on Ti-5 wt.% Si alloy and annealed at 600 °C possess higher PEC activity, yielding a higher photocurrent density of 0.83 mA/cm2 at 0 V vs. Ag/AgCl. The maximum photoconversion efficiency was 0.54%, which was 2.7 times the photoconversion efficiency of undoped TiO2.

  7. Fabrication of high aspect ratio TiO2 and Al2O3 nanogratings by atomic layer deposition

    DEFF Research Database (Denmark)

    Shkondin, Evgeniy; Takayama, Osamu; Michael-Lindhard, Jonas

    2016-01-01

    The authors report on the fabrication of TiO2 and Al2O3 nanostructured gratings with an aspect ratio of up to 50. The gratings were made by a combination of atomic layer deposition (ALD) and dry etch techniques. The workflow included fabrication of a Si template using deep reactive ion etching...... spectroscopy. The approach presented opens the possibility to fabricate high quality optical metamaterials and functional nanostructures....

  8. Nanoscale self-recovery of resistive switching in Ar+ irradiated TiO2-x films

    Science.gov (United States)

    Barman, A.; Saini, C. P.; Sarkar, P. K.; Das, D.; Dhar, S.; Singh, M.; Sinha, A. K.; Kanjilal, D.; Gupta, M.; Phase, D. M.; Kanjilal, A.

    2017-11-01

    Nanoscale evidence of self-recovery in resistive switching (RS) behavior was found in TiO2-x film by conductive atomic force microscopy when exposed to Ar+-ions above a threshold fluence of 1  ×  1016 ions cm-2. This revealed an evolution and gradual disappearance of bipolar RS-loops, followed by reappearance with increasing number of voltage sweep. This was discussed in the realm of oxygen vacancy (OV) driven formation, dissolution and reformation of conducting filaments. The presence of OVs in ion-beam irradiated TiO2-x films was evidenced by decreasing trend of work function in scanning-Kelvin probe microscopy, and was further verified by x-ray absorption near edge spectroscopy at Ti and O-K edges.

  9. 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.

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

    International Nuclear Information System (INIS)

    Zhao Chun; Deng Huiping; Li Yuan; Liu Zhenzhong

    2010-01-01

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

  11. Designed fabrication of fluorine-doped carbon coated mesoporous TiO2 hollow spheres for improved lithium storage

    International Nuclear Information System (INIS)

    Geng, Hongbo; Ming, Hai; Ge, Danhua; Zheng, Junwei; Gu, Hongwei

    2015-01-01

    Graphical abstract: Hollow TiO 2 with mesoporous shell (MHTO) was successfully fabricated by a novel and controllable route, followed by fluorine-doped carbon coating the MHTO (MHTO-C/F), with the aim of enhancing the conductivity and stability of structures. - Highlights: • Anatase TiO 2 hollow spheres with mesoporous shells (MHTO) was fabricated via a facile and controllable route, to improve the lithium ion mobility as well as the stability of the architecture. • Fluorine-doped carbon derived from polyvinylidene difluoride was further encapsulated onto TiO 2 hollow spheres to improve the conductivity. • The composites could provide excellent electrochemical performance, which was desirable for the application of TiO 2 as an anode material in lithium ion batteries. - Abstract: In this manuscript, we demonstrated a facile route for the controllable design of “Fluorine (F)-doped carbon” (C/F)-treated TiO 2 hollow spheres with mesoporous shells (MHTO-C/F). The fabrication of this distinct mesoporous hollow structures and the C/F coating could effectively improve the electrolyte permeability and architectural stability, as well as electrical conductivity and lithium ion mobility. As anticipated, MHTO-C/F has several remarkable electrochemical properties, such as a high specific reversible capacity of 252 mA h g −1 , outstanding cycling stability of more than 210 mA h g −1 after 100 cycles at 0.5 C, and good rate performance of around 123 mA h g −1 at 5 C (1 C = 168 mA g −1 ). These properties are highly beneficial for lithium storage

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

    International Nuclear Information System (INIS)

    Bae, S.H.

    1981-01-01

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

  13. THE APPLICATION AND CHARACTERIZATION OF GRAPHENE DECORATED WITH TiO2 –Fe (1%-N ON COTTON FABRICS

    Directory of Open Access Journals (Sweden)

    DUMITRESCU Iuliana

    2017-05-01

    Full Text Available Doped TiO2/graphene nanocomposites are studied due to their capacity to absorb the visible rays and large applicability in photo-catalytic applications. In this paper, we summarize our experiments on the development of photocatalytic fabrics based on deposition of doped TiO2/graphene nanocomposites by ultrasound method. We have investigated the surface morphology by scanning electron microscopy (SEM and elemental composition was determinate through EDX. Other information were obtained from electrical resistivity analysis measured on Prostat PRS-801 instrument, evaluation of the cotton fabrics wettability by measuring the contact angle on a VCA Optima instrument and evaluation of the photo-catalytic properties of the treated fabrics under solar and visible light (Xenotest by measuring the trichromatic coordinates of the treated and untreated textile materials. The results demonstrated that the ultrasound is an effective method to deposit nanoparticles on textile materials and that the uniform dispersion of TiO2- graphene composites depends on sonication parameters. Also, the treatment used on textile materials doesn’t improve the electrical properties of the knit. The results obtain after evaluation of the photo-catalytic activity by photo degradation of methylene blue under visible and solar light show the performance of the developed fabrics and also that the photo-catalytic activity is high under visible light and solar light.

  14. A multifunctional cotton fabric using TiO2 and PCMs: introducing thermal comfort and self-cleaning properties

    Science.gov (United States)

    Scacchetti, F. A. P.; Pinto, E.; Soares, G.

    2017-10-01

    The development of materials with multiple functionalities is a market imperative that places new challenges on textile processing. The purpose of this study was to establish the conditions to obtain a cotton material that is comfortable, with self-cleaning and antimicrobial properties. For this purpose, microcapsules of phase change materials (mPCM) and titanium dioxide nanoparticles (TiO2 NP) were applied. The resulting fabrics were characterized with resource to infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), contact angle and scanning electron microscopy (SEM). The self-cleaning properties of treated fabrics were also analysed based on the photocatalytic ability of coated fabrics. Therefore, the decomposition of methyl orange (MO) and the degradation of red wine and curry spots under the irradiation of a solar simulator were analysed. Thus, the incorporation of TiO2 particles into the cotton fabric promoted self-cleaning and antibacterial characteristics, but the presence of PCM combined with TiO2 increases the bioactivity of materials.

  15. Photocatalytic activity of self-assembled porous TiO2 nano-columns array fabricated by oblique angle sputter deposition

    Science.gov (United States)

    Shi, Pengjun; Li, Xibo; Zhang, Qiuju; Yi, Zao; Luo, Jiangshan

    2018-04-01

    A well-separated and oriented TiO2 nano-columns arrays with porous structure were fabricated by the oblique angle sputter deposition technique and subsequently annealing at 450 °C in Ar/O2 mixed atmosphere. The deposited substrate was firstly modified by a template of self-assembled close-packed arrays of 500 nm-diameter silica (SiO2) spheres. Scanning electronic microscopic (SEM) images show that the porous columnar nanostructure is formed as a result of the geometric shadowing effect and surface diffusion of the adatoms in oblique angle deposition (OAD). X-ray diffraction (XRD) measurements reveal that the physically OAD film with annealing treatment are generally mixed phase of rutile and anatase TiO2 polymorphic forms. The morphology induced absorbance and band gap tuning by different substrates was demonstrated by the UV–vis spectroscopy. The well-separated one-dimensional (1D) nano-columns array with specific large porous surface area is beneficial for charge separation in photocatalytic degradation. Compared with compact thin film, such self-assembled porous TiO2 nano-columns array fabricated by oblique angle sputter deposition performed an enhanced visible light induced photocatalytic activity by decomposing methyl orange (MO) solution. The well-designed periodic array-structured porous TiO2 films by using modified patterned substrates has been demonstrated significantly increased absorption edge in the UV-visible light region with a narrower optical band gap, which are expected to be favorable for application in photovoltaic, lithium-ion insertion and photocatalytic, etc.

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  17. Rapid fabrication of TiO2@carboxymethyl cellulose coatings capable of shielding UV, antifog and delaying support aging.

    Science.gov (United States)

    Li, Xiaozhou; Lv, Junping; Li, Dehuai; Wang, Lin

    2017-08-01

    Agricultural plastic films capable of shielding UV, filtering visible light and antifog are important to prolong their life and protect safeties of agriculturists and crops. In this work, high stable and small size TiO 2 @polymer nanoparticles (NPs) were prepared by an efficient one-pot microwave synthesis using titanic sulfate as Ti resource, carboxymethyl cellulose sodium (CMC) as complexing agent and stabilizer. The TiO 2 @CMC NPs obtained were then utilized to fabricate poly(ethylene imine) (PEI)/TiO 2 @CMC coatings on the surface of polypropylene films by a layer-by-layer assembly technique. The TiO 2 @CMC NPs show rapid deposition rate because small, spherical and anion-rich TiO 2 @CMC NPs possess large specific surface area and fast diffusion rate. More importantly, property experiments confirm that (PEI/TiO 2 @CMC)*15 coatings can not only effectively shield UV rays, filter visible light and prevent fogging but also delay the aging of their supports. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Development of Cotton Fabrics with Durable UV Protective and Self-cleaning Property by Deposition of Low TiO2 Levels through Sol-gel Process.

    Science.gov (United States)

    Mishra, Anu; Butola, Bhupendra Singh

    2018-01-19

    In this article, the deposition of TiO 2 on cotton fabric using sol-gel technique has been described. Various process routes (pad-dry-cure, pad-dry-hydrothermal and pad-dry-solvothermal) were examined to impart a stable coating of TiO 2 on fabric. The role of precursor concentration, process temperature and time of treatment were studied to aim at a wash durable, UV protective and self-cleaning property in the treated fabric. EDX and ICP-MS techniques were used to examine the add-on percentage of TiO 2 on cotton fabrics treated via different routes. It has been found that the TiO 2 remains largely amorphous and nondurable if it is given a short thermal treatment. To convert the deposited TiO 2 to its anatase crystal form, a prolonged hydrothermal treatment for at least 3 h needs to be given. TiO 2 deposition levels of less than 0.1% were found to be effective in imparting reasonable degree of UV protection and self-cleaning property to the cotton fabric. The self-cleaning ability of the treated fabric against coffee stain was also studied and was found to be related to the process route and the deposition levels of TiO 2 . © 2018 The American Society of Photobiology.

  19. Ultrafast Flame Annealing of TiO2 Paste for Fabricating Dye-Sensitized and Perovskite Solar Cells with Enhanced Efficiency.

    Science.gov (United States)

    Kim, Jung Kyu; Chai, Sung Uk; Cho, Yoonjun; Cai, Lili; Kim, Sung June; Park, Sangwook; Park, Jong Hyeok; Zheng, Xiaolin

    2017-11-01

    Mesoporous TiO 2 nanoparticle (NP) films are broadly used as electrodes in photoelectrochemical cells, dye-sensitized solar cells (DSSCs), and perovskite solar cells (PSCs). State-of-the-art mesoporous TiO 2 NP films for these solar cells are fabricated by annealing TiO 2 paste-coated fluorine-doped tin oxide glass in a box furnace at 500 °C for ≈30 min. Here, the use of a nontraditional reactor, i.e., flame, is reported for the high throughput and ultrafast annealing of TiO 2 paste (≈1 min). This flame-annealing method, compared to conventional furnace annealing, exhibits three distinct benefits. First, flame removes polymeric binders in the initial TiO 2 paste more completely because of its high temperature (≈1000 °C). Second, flame induces strong interconnections between TiO 2 nanoparticles without affecting the underlying transparent conducting oxide substrate. Third, the flame-induced carbothermic reduction on the TiO 2 surface facilitates charge injection from the dye/perovskite to TiO 2 . Consequently, when the flame-annealed mesoporous TiO 2 film is used to fabricate DSSCs and PSCs, both exhibit enhanced charge transport and higher power conversion efficiencies than those fabricated using furnace-annealed TiO 2 films. Finally, when the ultrafast flame-annealing method is combined with a fast dye-coating method to fabricate DSSC devices, its total fabrication time is reduced from over 3 h to ≈10 min. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    Science.gov (United States)

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

    2018-01-01

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

  1. Fabrication and characterization of uniform TiO2 nanotube arrays by ...

    Indian Academy of Sciences (India)

    Titanium dioxide (TiO2) has been widely investigated as a key material for ... photonic crystals, catalysis, photocatalysis (Livraghi et al. 2005) and ... As a catalyst and/or catalyst support, .... of XRD analysis is supported by the Raman spectra of.

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  3. TiO2/beads as a photocatalyst for the degradation of X3B azo dye

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The feasibility of photocatalytic degradation of X3B azo dye by TiO2/beads photocatalyst was studied. The effects of parameters such as the amount of TiO2/beads, airflow, as well as the concentrations of H2O2, Fe3+, Mg2+ and Na+ on the photocatalytic degradation of X3B azo dye were also studied. The results showed that 25 mg/dm3 X3B azo dye can be photocatalytically degraded completely by 30 min illumination with a 375W medium pressure mercury lamp. Adding a small amount of H2O2 or Fe3+, the efficiencies of photocatalytic degradation of X3B azo dye were increased rapidly. The mechanisms of the reaction and the role of the additives were also investigated. After 120 hours TiO2/beads showed no significant loss of the photocatalytic activity.

  4. Structure and dye-sensitized solar cell application of TiO2 nanotube arrays fabricated by the anodic oxidation method

    Science.gov (United States)

    Ok, Seon-Yeong; Cho, Kwon-Koo; Kim, Ki-Won; Ryu, Kwang-Sun

    2010-05-01

    Well-ordered TiO2 nanotube arrays were fabricated by the potentiostatic anodic oxidation method using pure Ti foil as a working electrode and ethylene glycol solution as an electrolyte with the small addition of NH4F and H2O. The influence of anodization temperature and time on the morphology and formation of TiO2 nanotube arrays was examined. The TiO2 nanotube arrays were applied as a photoelectrode to dye-sensitized solar cells. Regardless of anodizing temperature and time, the average diameter and wall thickness of TiO2 nanotube arrays show a similar value, whereas the length increases with decreasing reaction temperature. The conversion efficiency is very low, which is due to a morphology breaking of the TiO2 nanotube arrays in the manufacturing process of a photoelectrode.

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

    Science.gov (United States)

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

    2014-05-01

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

  6. Design and fabrication of a TiO2/nano-silicon composite visible light photocatalyst

    International Nuclear Information System (INIS)

    Lin, C.Y.; Fang, Y.K.; Kuo, C.H.; Chen, S.F.; Lin, C.-S.; Chou, T.H.; Lee, Y.-H.; Lin, J.-C.; Hwang, S.-B.

    2006-01-01

    Nano-silicon (nc-Si) was utilized as the charges generator to promote the photocatalytic and super-hydrophilic reactivity of TiO 2 film under visible light irradiation. The photocatalytic ability of TiO 2 /nc-Si composite photocatalyst was evaluated by a set of experiments to photodecompose 100 ppm methylene blue (MB) in aqueous solution. And the super-hydrophilic property was characterized by measuring the water droplet contacts angle, under visible light irradiation in atmospheric air and at room temperature. Under 100 mW/cm 2 visible light irradiation, the droplet contact angles were reduced to 0 deg. within 4 h with nc-Si charge generator. Additionally, the rate constant of MB photo-degradation was promoted 6.6 times

  7. Fabrication of TiO2 Crystalline Coatings by Combining Ti-6Al-4V Anodic Oxidation and Heat Treatments

    Directory of Open Access Journals (Sweden)

    María Laura Vera

    2015-01-01

    Full Text Available The bio- and hemocompatibility of titanium alloys are due to the formation of a TiO2 layer. This natural oxide may have fissures which are detrimental to its properties. Anodic oxidation is used to obtain thicker films. By means of this technique, at low voltages oxidation, amorphous and low roughness coatings are obtained, while, above a certain voltage, crystalline and porous coatings are obtained. According to the literature, the crystalline phases of TiO2, anatase, and rutile would present greater biocompatibility than the amorphous phase. On the other hand, for hemocompatible applications, smooth and homogeneous surfaces are required. One way to obtain crystalline and homogeneous coatings is by heat treatments after anodic oxidation. The aim of this study is to evaluate the influence of heat treatments on the thickness, morphology, and crystalline structure of the TiO2 anodic coatings. The characterization was performed by optical and scanning electron microscopy, X-ray diffraction, and X-ray reflectometry. Coatings with different colors of interference were obtained. There were no significant changes in the surface morphology and roughness after heat treatment of 500°C. Heat treated coatings have different proportions of the crystalline phases, depending on the voltage of anodic oxidation and the temperature of the heat treatment.

  8. Fabrication of TiO2/PU Superhydrophobic Film by Nanoparticle Assisted Cast Micromolding Process.

    Science.gov (United States)

    Li, Jie; Zheng, Jianyong; Zhang, Jing; Feng, Jie

    2016-06-01

    Lotus-like surfaces have attracted great attentions in recent years for their wide applications in water repellency, anti-fog and self-cleaning. This paper introduced a novel process, nanoparticle assisted cast micromolding, to create polymer film with superhydrophobic surface. Briefly, waterborne polyurethane (WPU) sol and nano TiO2/WPU sol were each cast onto the featured surfaces of the poly(dimethylsiloxane) (PDMS) stamps replicated from fresh lotus leaves. After being dried and peeled off from the stamps, PU and TiO2/WPU replica films were created respectively. To the former, only high hydrophobic property was observed with static water contact angle (WCA) at 142.5 degrees. While to the later, superhydrophobic property was obtained with WCA more than 150 degrees and slide angle less than 3 degrees. Scanning electron microscopy (SEM) imaging showed that the PU replica film only had the micro-papillas and the TiO2/PU replica film not only had micro papillas but also had a large number of nano structures distributed on and between the micro-papillas. Such nano and micro hierarchical structures were very similar with those on the natural lotus leaf surface, thus was the main reason for causing superhydrophobic property. Although an elastic PDMS stamp from lotus leaf was used in herein process, hard molds may also be used in theory. This study supplied an alternative technique for large scale production of polymeric films with superhydrophobic.

  9. Au Nanoclusters Sensitized Black TiO2-x Nanotubes for Enhanced Photodynamic Therapy Driven by Near-Infrared Light.

    Science.gov (United States)

    Yang, Dan; Gulzar, Arif; Yang, Guixin; Gai, Shili; He, Fei; Dai, Yunlu; Zhong, Chongna; Yang, Piaoping

    2017-12-01

    The low reactive oxygen species production capability and the shallow tissue penetration of excited light (UV) are still two barriers in photodynamic therapy (PDT). Here, Au cluster anchored black anatase TiO 2- x nanotubes (abbreviated as Au 25 /B-TiO 2- x NTs) are synthesized by gaseous reduction of anatase TiO 2 NTs and subsequent deposition of noble metal. The Au 25 /B-TiO 2- x NTs with thickness of about 2 nm exhibit excellent PDT performance. The reduction process increased the density of Ti 3+ on the surface of TiO 2 , which effectively depresses the recombination of electron and hole. Furthermore, after modification of Au 25 nanoclusters, the PDT efficiency is further enhanced owing to the changed electrical distribution in the composite, which forms a shallow potential well on the metal-TiO 2 interface to further hamper the recombination of electron and hole. Especially, the reduction of anatase TiO 2 can expend the light response range (UV) of TiO 2 to the visible and even near infrared (NIR) light region with high tissue penetration depth. When excited by NIR light, the nanoplatform shows markedly improved therapeutic efficacy attributed to the photocatalytic synergistic effect, and promotes separation or restrained recombination of electron and hole, which is verified by experimental results in vitro and in vivo. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Fabrication and properties of an immobilized P25TiO2-montmorillonite bilayer system for the synergistic photocatalytic–adsorption removal of methylene blue

    International Nuclear Information System (INIS)

    Ngoh, Y.S.; Nawi, M.A.

    2016-01-01

    Highlights: • P25TiO 2 and montmorillonite was integrated via an immobilized bilayer approach. • Synergistic dual photocatalytic–adsorptive removal of MB was observed. • Removal rate of MB was 4 times better than P25TiO 2 alone. • Excellent reusability with sustainable rate of removal of MB. • Treated water can be discharged directly without the need of a filtration system. - Abstract: A bilayer immobilized system consisting of a mesoporous montmorillonite (MT) as the sublayer and a porous P25TiO 2 toplayer was successfully fabricated on a glass plate. The MT sublayer was immobilized onto the glass plate by means of a glutaraldehyde (GLA) cross-linked poly (vinyl) alcohol (PVA) as the binder (MT-PVAB) while the top layer constituted of nano-sized TiO 2 bound by the ENR-PVC polymer blends (P-25TiO 2 ). The incorporation of MT-PVAB to P-25TiO 2 caused a reduction in the band gap energy while PLS emission spectra suggested higher separation rate for the photo-generated electron–hole pairs in the P-25TiO 2 /MT-PVAB/GP. The photocatalytic–adsorption removal experiments showed that the P-25TiO 2 /MT-PVAB/GP enhanced removal rate of MB by an average of 4 times as compared with the immobilized monolayer P-25TiO 2 on a glass plate (P-25TiO 2 /GP).

  11. Preparation of 13X from Waste Quartz and Photocatalytic Reaction of Methyl Orange on TiO2/ZSM-5, 13X and Y-Zeolite.

    Science.gov (United States)

    Wang, Jia-Jie; Jing, You-Hai; Ouyang, Tong; Chang, Chang-Tang

    2015-08-01

    TiO2 photocatalytic reactions not only remove a variety of organic pollutants via complete mineralization, but also destroy the bacterial cell wall and cell membrane, thus playing an important bactericidal role. However, the post-filtration procedures to separate nanometer-levels of TiO2 and the gradual inactivity of photocatalyst during continuous use are defects that limit its application. In this case, we propose loading TiO2 on zeolite for easy separation and 13X is considered as a promising one. In our study, 13X-zeolite was prepared by a hydrothermal method and the source of Si was extracted from waste quartz sand. For comparison, commercial zeolite with different microporous and mesoporous diameters (ZSM-5 and Y-zeolites) were also used as TiO2 supports. The pore size of the three kinds of zeolites are as follows: Y-zeolite > 13X > ZSM-5. Different TiO2 loading content over ZSM-5, 13X and Y-zeolite were prepared by the sol-gel method. XRD, FTIR, BET, UV-vis, TGA and SEM were used for investigation of material characteristics. In addition, the efficiencies of mineralization and photodegradation were studied in this paper. The effects of the loading ratio of TiO2 over zeolites, initial pH, and concentration on photocatalytic performance are investigated. The relationship between best loading content of TiO2 and pore size of the zeolite was studied. The possible roles of the ZSM-5, 13X-zeolites and Y-zeolites support on the reactions and the possible mechanisms of effects were also explored. The best loading content of TiO2 over ZSM-5, 13X and Y-zeolite was found to be 50 wt%, 12.5 wt% and 7 wt%, respectively. The optimum pH condition is 3 with TiO2 over ZSM-5, 13X-zeolites and Y-zeolites. The results showed that the degradation and mineralization efficiency of 12.5 wt%GT13X (TiO2 over 13X) after 90 min irradiation reached 57.9% and 22.0%, which was better than that of 7 wt%GTYZ (TiO2 over Y-zeolites) while much lower than that of 50 wt%GTZ (TiO2 over ZSM-5

  12. Cotton fabric coated with nano TiO2-acrylate copolymer for photocatalytic self-cleaning by in-situ suspension polymerization

    International Nuclear Information System (INIS)

    Jiang Xue; Tian Xiuzhi; Gu Jian; Huang Dan; Yang Yiqi

    2011-01-01

    Two kinds of nano TiO 2 -polyacrylate hybrid dispersions, TBM-w and TBM-e were synthesized by in-situ suspension polymerization and solution polymerization respectively, in order to fix the nano TiO 2 on fabrics. The photocatalytic self-cleaning fabrics have received much attention in recent years for its water-saving and environment-protection advantages. However, the fixation of the photocatalyst on fabrics is still a key problem that inhibits industrialization of these eco-friendly fabrics. The cotton fabric was treated by the two hybrid dispersions. The photocatalytic self-cleaning property was characterized. Infrared spectroscopy, burning loss test and thermogravimetry showed that some copolymer chains entangled with the nano TiO 2 . Transmission electron microscope illustrated that there was a polymeric layer on the surface of nano TiO 2 . The average diameter of TBM-w was smaller than that of TBM-e based on size analysis. The photocatalytic decoloration of the grape syrup indicated that the fabric with TiO 2 -polymer hybrid had excellent self-cleaning property.

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

    Science.gov (United States)

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

    2017-10-04

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

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

    International Nuclear Information System (INIS)

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

    2006-01-01

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

  15. Development of Multi-functional Properties on Cotton Fabric by In Situ Application of TiO2 and ZnO Nanoparticles

    Science.gov (United States)

    Butola, B. S.; Garg, Aayush; Garg, Aman; Chauhan, Indu

    2018-06-01

    Cotton fabrics functionalized with different combinations of TiO2 and ZnO were evaluated for multifunctional properties including UV protection, antimicrobial and self-cleaning. The ZnO nanoparticles synthesized using sol gel method were applied on cotton fabric by pad-dry-cure method and TiO2 was deposited in situ. The deposition of both TiO2 and ZnO was examined and confirmed by SEM and EDX analysis. Application of both metal oxides resulted in good improvement in UV protection of treated fabrics. The fabrics which were finished with combination of both Zinc and Titanium oxides, showed UPF rating of 50+ as compared to UPF rating of untreated cotton, which was only 5. The same fabrics also showed higher self-cleaning extent as compared to untreated cotton fabric. It was found that the sequence of application of ZnO and TiO2 affected the antimicrobial activity of the finished fabric and also the durability. When application of TiO2 was followed by ZnO, the combination resulted in development of excellent antimicrobial property against Escherichia coli ( 99% colony reduction) which was retained after 10 wash cycles. However, when application of ZnO nanoparticles was followed by application of TiO2, the improvement in antimicrobial activity was found to be moderate ( 48% colony reduction) and had poor wash durability. Hence, the specific sequence of application of these metals oxides can be utilized for obtaining good durability of the multifunctional properties on cotton fabric.

  16. Development of Multi-functional Properties on Cotton Fabric by In Situ Application of TiO2 and ZnO Nanoparticles

    Science.gov (United States)

    Butola, B. S.; Garg, Aayush; Garg, Aman; Chauhan, Indu

    2018-05-01

    Cotton fabrics functionalized with different combinations of TiO2 and ZnO were evaluated for multifunctional properties including UV protection, antimicrobial and self-cleaning. The ZnO nanoparticles synthesized using sol gel method were applied on cotton fabric by pad-dry-cure method and TiO2 was deposited in situ. The deposition of both TiO2 and ZnO was examined and confirmed by SEM and EDX analysis. Application of both metal oxides resulted in good improvement in UV protection of treated fabrics. The fabrics which were finished with combination of both Zinc and Titanium oxides, showed UPF rating of 50+ as compared to UPF rating of untreated cotton, which was only 5. The same fabrics also showed higher self-cleaning extent as compared to untreated cotton fabric. It was found that the sequence of application of ZnO and TiO2 affected the antimicrobial activity of the finished fabric and also the durability. When application of TiO2 was followed by ZnO, the combination resulted in development of excellent antimicrobial property against Escherichia coli ( 99% colony reduction) which was retained after 10 wash cycles. However, when application of ZnO nanoparticles was followed by application of TiO2, the improvement in antimicrobial activity was found to be moderate ( 48% colony reduction) and had poor wash durability. Hence, the specific sequence of application of these metals oxides can be utilized for obtaining good durability of the multifunctional properties on cotton fabric.

  17. Fabrication of chitin-chitosan/nano TiO2-composite scaffolds for tissue engineering applications.

    Science.gov (United States)

    Jayakumar, R; Ramachandran, Roshni; Divyarani, V V; Chennazhi, K P; Tamura, H; Nair, S V

    2011-03-01

    In this study, we prepared chitin-chitosan/nano TiO(2) composite scaffolds using lyophilization technique for bone tissue engineering. The prepared composite scaffold was characterized using SEM, XRD, FTIR and TGA. In addition, swelling, degradation and biomineralization capability of the composite scaffolds were evaluated. The developed composite scaffold showed controlled swelling and degradation when compared to the control scaffold. Cytocompatibility of the scaffold was assessed by MTT assay and cell attachment studies using osteoblast-like cells (MG-63), fibroblast cells (L929) and human mesenchymal stem cells (hMSCs). Results indicated no sign of toxicity and cells were found attached to the pore walls within the scaffolds. These results suggested that the developed composite scaffold possess the prerequisites for tissue engineering scaffolds and it can be used for tissue engineering applications. Copyright © 2010 Elsevier B.V. All rights reserved.

  18. A Macroporous TiO2 Oxygen Sensor Fabricated Using Anodic Aluminium Oxide as an Etching Mask

    Directory of Open Access Journals (Sweden)

    Sheng-Po Wu

    2010-01-01

    Full Text Available An innovative fabrication method to produce a macroporous Si surface by employing an anodic aluminium oxide (AAO nanopore array layer as an etching template is presented. Combining AAO with a reactive ion etching (RIE processes, a homogeneous and macroporous silicon surface can be effectively configured by modulating AAO process parameters and alumina film thickness, thus hopefully replacing conventional photolithography and electrochemical etch methods. The hybrid process integration is considered fully CMOS compatible thanks to the low-temperature AAO and CMOS processes. The gas-sensing characteristics of 50 nm TiO2 nanofilms deposited on the macroporous surface are compared with those of conventional plain (or non-porous nanofilms to verify reduced response noise and improved sensitivity as a result of their macroporosity. Our experimental results reveal that macroporous geometry of the TiO2 chemoresistive gas sensor demonstrates 2-fold higher (~33% improved sensitivity than a non-porous sensor at different levels of oxygen exposure. In addition, the macroporous device exhibits excellent discrimination capability and significantly lessened response noise at 500 °C. Experimental results indicate that the hybrid process of such miniature and macroporous devices are compatible as well as applicable to integrated next generation bio-chemical sensors.

  19. Fabrication of TiO2/MoS2@zeolite photocatalyst and its photocatalytic activity for degradation of methyl orange under visible light

    International Nuclear Information System (INIS)

    Zhang, Weiping; Xiao, Xinyan; Zheng, Lili; Wan, Caixia

    2015-01-01

    Graphical abstract: A novel approach was developed for fabrication of TiO 2 /MoS 2 @zeolite photocatalyst using bulk MoS 2 as a photosensitizer and zeolite as carrier. The as-prepared TiO 2 /MoS 2 @zeolite composite exhibited excellent photocatalytic performance for degradation of methyl orange under visible-light irradiation. - Highlights: • Ultrasound-exfoliation and hydrothermal reforming technique were employed for generating nano-MoS 2 from micro-MoS 2 . • The embedded sensitizer composite mode of (TiO 2 /MoS 2 /TiO 2 ) was used in the fabrication of TiO 2 /MoS 2 @zeolite composite photocatalyst. • The photocatalytic mechanism of TiO 2 /MoS 2 @zeolite photocatalyst was presented. - Abstract: TiO 2 /MoS 2 @zeolite composite photocatalysts with visible-light activity were fabricated via a simple ultrasonic-hydrothermal synthesis method, using TiCl 4 as Ti source, MoS 2 as a direct sensitizer, glycerol water solution with certain dispersion agent as hydrolytic agent, and zeolite as carrier. The structure, morphology, composition, optical properties, and specific surface area of the as-prepared photocatalysts were characterized by using XRD, FTIR, SEM–EDS, TEM, XPS, UV–vis, PL and BET analyzer, respectively. And the photocatalytic degradation of methyl orange (MO) in aqueous suspension has been employed to evaluate the photocatalytic activity and degradation kinetics of as-prepared photocatalysts with xenon lamp as irradiation source. The results indicate that: (1) TiO 2 /MoS 2 @zeolite composite photocatalysts exhibit enhanced photocatalytic activities for methyl orange (MO) degradation compared to Degussa P25; (2) photocatalytic degradation of MO obeys Langmuir–Hinshelwood kinetic model (pseudo-first order reaction), and its degradation rate constant (k app ) (2.304 h −1 ) is higher than that of Degussa P25 (0.768 h −1 ); (3) the heterostructure consisted of zeolite, MoS 2 and TiO 2 nanostructure could provide synergistic effect for degradation

  20. Water adsorption on TiO2 surfaces probed by soft X-ray spectroscopies: bulk materials vs. isolated nanoparticles

    Science.gov (United States)

    Benkoula, Safia; Sublemontier, Olivier; Patanen, Minna; Nicolas, Christophe; Sirotti, Fausto; Naitabdi, Ahmed; Gaie-Levrel, François; Antonsson, Egill; Aureau, Damien; Ouf, François-Xavier; Wada, Shin-Ichi; Etcheberry, Arnaud; Ueda, Kiyoshi; Miron, Catalin

    2015-01-01

    We describe an experimental method to probe the adsorption of water at the surface of isolated, substrate-free TiO2 nanoparticles (NPs) based on soft X-ray spectroscopy in the gas phase using synchrotron radiation. To understand the interfacial properties between water and TiO2 surface, a water shell was adsorbed at the surface of TiO2 NPs. We used two different ways to control the hydration level of the NPs: in the first scheme, initially solvated NPs were dried and in the second one, dry NPs generated thanks to a commercial aerosol generator were exposed to water vapor. XPS was used to identify the signature of the water layer shell on the surface of the free TiO2 NPs and made it possible to follow the evolution of their hydration state. The results obtained allow the establishment of a qualitative determination of isolated NPs’ surface states, as well as to unravel water adsorption mechanisms. This method appears to be a unique approach to investigate the interface between an isolated nano-object and a solvent over-layer, paving the way towards new investigation methods in heterogeneous catalysis on nanomaterials. PMID:26462615

  1. Fabrication of TiO2 nanoparticles/nanorod composite arrays via a two-step method for efficient dye-sensitized solar cells

    Directory of Open Access Journals (Sweden)

    Jingyang Wang

    2014-12-01

    Full Text Available TiO2 nanoparticles/nanorod composite arrays were prepared on the F-doped tin oxide (FTO substrate through a two-step method of hydrothermal and d.c. magnetron sputtering. The microstructure and optical properties of the samples were characterized respectively by means of X-ray diffraction (XRD, field-emission scanning electron microscopy (FESEM and UV–vis spectrometer. The results showed that the TiO2 composite nanorod arrays possess the nature of high surface area for more dye molecule absorption and the strong light scattering effects. The dye sensitized solar cells (DSSCs based on TiO2 composite nanorod arrays exhibited a 80% improvement in the overall energy conversion efficiency compared with the pure TiO2 nanorod arrays photoanode.

  2. Fabrication and assembly of two-dimensional TiO2/WO3·H2O heterostructures with type II band alignment for enhanced photocatalytic performance

    Science.gov (United States)

    Xu, Tao; Wang, Yun; Zhou, Xiaofang; Zheng, Xiaoli; Xu, Qun; Chen, Zhimin; Ren, Yumei; Yan, Bo

    2017-05-01

    The recombination of photo-induced charges is one of the main issues to limit the large-scale applications in photocatalysis and photoelectrocatalysis. To improve the charge separation, we fabricate a novel type II 2D ultrathin TiO2/WO3·H2O heterostructures with the assistance of supercritical CO2 (SC CO2) in this work. The as-fabricated heterostructures possess high photocatalytic activity for the degradation of methyl orange(MO) and high photocurrent response under simulated solar light (AM 1.5). For the TiO2/WO3·H2O heterostructures, the MO solution could be degraded by 95.5% in 150 min, and the photocurrent density reaches to 6.5 μA cm-2, exhibiting a significant enhancement compared with pure TiO2 and WO3·H2O nanosheets.

  3. Fabrication of La-doped TiO2 Film Electrode and investigation of its electrocatalytic activity for furfural reduction

    International Nuclear Information System (INIS)

    Wang, Fengwu; Xu, Mai; Wei, Lin; Wei, Yijun; Hu, Yunhu; Fang, Wenyan; Zhu, Chuan Gao

    2015-01-01

    Lanthanum trivalent ions (La 3+ ) doped nano-TiO 2 film electrode was prepared by the sol–gel method. The prepared electrode was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV). The electrocatalytic properties of the roughened TiO 2 film electrode towards the electrocatalytic reduction of furfural to furfural alcohol were evaluated by CV and preparative electrolysis experiments. The results of the optimum molar ratio of La: Ti was 0.005:1. Experimental evidence was presented that the La nano-TiO 2 electrode exhibited higher electrocatalytic activity for the reduction of furfural than the undoped nano-TiO 2 electrode in N,N-dimethylformamide medium. Bulk electrolysis studies were also carried out for the reduction of furfural and the product was confirmed by NMR

  4. Co-electrospinning fabrication and photocatalytic performance of TiO2/SiO2 core/sheath nanofibers with tunable sheath thickness

    International Nuclear Information System (INIS)

    Cao, Houbao; Du, Pingfan; Song, Lixin; Xiong, Jie; Yang, Junjie; Xing, Tonghai; Liu, Xin; Wu, Rongrong; Wang, Minchao; Shao, Xiaoli

    2013-01-01

    Graphical abstract: - Highlights: • The core–sheath TiO 2 /SiO 2 nanofibers were fabricated by co-electrospinning technique. • The catalytic property of nanofibers with different sheath thickness was studied. • The potential methods of improving catalytic efficiency are suggested. - Abstract: In this paper, core/sheath TiO 2 /SiO 2 nanofibers with tunable sheath thickness were directly fabricated via a facile co-electrospinning technique with subsequent calcination at 500 °C. The morphologies and structures of core/sheath TiO 2 /SiO 2 nanofibers were characterized by TGA, FESEM, TEM, FTIR, XPS and BET. It was found that the 1D core/sheath nanofibers are made up of anatase–rutile TiO 2 core and amorphous SiO 2 sheath. The influences of SiO 2 sheath and its thickness on the photoreactivity were evaluated by observing photo-degradation of methylene blue aqueous solution under the irradiation of UV light. Compared with pure TiO 2 nanofibers, the core/sheath TiO 2 /SiO 2 nanofibers performed a better catalytic performance. That was attributed to not only efficient separation of hole–electron pairs resulting from the formation of heterojunction but also larger surface area and surface silanol group which will be useful to provide higher capacity for oxygen adsorption to generate more hydroxyl radicals. And the optimized core/sheath TiO 2 /SiO 2 nanofibers with a sheath thickness of 37 nm exhibited the best photocatalytic performance

  5. Superhydrophobicity construction with dye-sensitised TiO2 on fabric surface for both oil/water separation and water bulk contaminants purification

    Science.gov (United States)

    Yu, Linfeng; Zhang, Shengmiao; Zhang, Meng; Chen, Jianding

    2017-12-01

    For the promising material for both oil/water separation and water-soluble contaminants, the Dye@TiO2-TEOS/VTEO hybrid modified polyester fabric is developed by a simple dip-coating process, which combines Dye-sensitised TiO2 with silicon contained superhydrophobic coating to guarantee the long-term stability of Dye-sensitised TiO2 system as well as material's sustainability. The modified fabric possesses selective oil/water seperation properties towards water and oil, besides, mechanical, acid and alkali durability shows this material's appropriate performance on oil/water separation. UV-Vis absorption spectrum reveals the Dye 4-(2H-imidazol-2-ylazo) benzoic acid could sensitize the semiconductor TiO2 for visible light catalytic organic pollutant degradation that is also confirmed by methylene blue degradation experiment. Density Functional calculation (DFT) witnesses that HOMO, HOMO-1 of Dye contributed by oxygen bonding to TiO2 can insert into TiO2 band gap and result in low energy electron excitation. The ability of oil/water separation and water-soluble contaminants purification provides the material opportunity to practical applications in environmental restoration and human life.

  6. An instant photo-excited electrons relaxation on the photo-degradation properties of TiO2-x films

    CSIR Research Space (South Africa)

    Nkosi, SS

    2014-11-01

    Full Text Available of Photochemistry and Photobiology A: Chemistry 293 (2014) 72–80 An instant photo-excited electrons relaxation on the photo- degradation properties of TiO2−x films S.S. Nkosi a,b,∗, I. Kortidis d, D.E. Motaungc,∗, P.R. Makgwanec, O.M. Ndwandwe b, S.S. Rayc, G...

  7. Optimization of process conditions for the production of TiO2–xNy ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 37; Issue 6 ... Based on the results in preliminary experiments, we selected molar ratio of surfactant to Ti, molar ratio of acetylacetone to Ti, molar ratio of water to Ti and calcination temperature as the key process factors affecting the roughness of TiO2–N film.

  8. Optimization of process conditions for the production of TiO2–xNy ...

    Indian Academy of Sciences (India)

    Administrator

    by sol–gel process using response surface methodology. RUI LIUa ... atoms in the TiO2 lattice and, thus, the band-gap energy is narrower .... of the samples were investigated by a field emission scanning ..... nificantly by the validation data.

  9. Band alignment of TiO2/FTO interface determined by X-ray photoelectron spectroscopy: Effect of annealing

    Directory of Open Access Journals (Sweden)

    Haibo Fan

    2016-01-01

    Full Text Available The energy band alignment between pulsed-laser-deposited TiO2 and FTO was firstly characterized using high-resolution X-ray photoelectron spectroscopy. A valence band offset (VBO of 0.61 eV and a conduction band offset (CBO of 0.29 eV were obtained across the TiO2/FTO heterointerface. With annealing process, the VBO and CBO across the heterointerface were found to be -0.16 eV and 1.06 eV, respectively, with the alignment transforming from type-I to type-II. The difference in the band alignment is believed to be dominated by the core level down-shift of the FTO substrate, which is a result of the oxidation of Sn. Current-voltage test has verified that the band alignment has a significant effect on the current transport of the heterojunction.

  10. Fabrication of efficient TiO2-RGO heterojunction composites for hydrogen generation via water-splitting: Comparison between RGO, Au and Pt reduction sites

    Science.gov (United States)

    El-Bery, Haitham M.; Matsushita, Yoshihisa; Abdel-moneim, Ahmed

    2017-11-01

    A facile one-step synthesis approach of M/TiO2/RGO (M = Au or Pt) ternary composite by hydrothermal treatment for hydrogen generation via water-splitting was investigated. Photocurrent response measurements revealed that TiO2 (P25) nanoparticles anchored on the reduced graphene oxide (RGO) surface exhibited a p-n heterojunction interface by changing the photocurrent direction with the applied bias from reverse to forward potential. H2 evolution rate of TiO2/RGO (5 wt.%) composite was substantially enhanced by 12-fold in comparison to bare TiO2 under simulated solar light irradiation. Cyclic volatmmetry measurements manifested, that the optimized 0.3 wt.% of platinum metal loaded on TiO2/RGO composite was the most active catalytic reduction sites for hydrogen generation reaction with an initial hydrogen rate of 670 μmol h-1. This study sheds the light on the tunable semiconductor type of TiO2/RGO composite fabricated by solution mixing pathway and its merits to improve the photocatalytic activity.

  11. Fabrication of doped Titania (TiO2) nano-catalysts in the shape of nanofibers

    DEFF Research Database (Denmark)

    Marani, Debora; Silva, Rafael Hubert; Zhang, Wenjing (Angela)

    Nanostructured materials have attracted incredible interest during the recent years for a large variety of applications. In heterogeneous catalysis the use of nano-sized catalytic materials is expected to significantly impact the performances of materials as consequence of their large surface......-to-volume ratios [1]. The “nanomaterial” approach enables to achieve structures with incredible large exposed surface area. When nanofibers are used as nano-catalysts, the further advantage of a quite open porous structure is further achieved. In this work, nanomaterial approach was adopted to fabricate nano...

  12. H irradiation effects on the GaAs-like Raman modes in GaAs1-xNx/GaAs1-xNx:H planar heterostructures

    Science.gov (United States)

    Giulotto, E.; Geddo, M.; Patrini, M.; Guizzetti, G.; Felici, M.; Capizzi, M.; Polimeni, A.; Martelli, F.; Rubini, S.

    2014-12-01

    The GaAs-like longitudinal optical phonon frequency in two hydrogenated GaAs1-xNx/GaAs1-xNx:H microwire heterostructures—with similar N concentration, but different H dose and implantation conditions—has been investigated by micro-Raman mapping. In the case of GaAs0.991N0.009 wires embedded in barriers where GaAs-like properties are recovered through H irradiation, the phonon frequency in the barriers undergoes a blue shift with respect to the wires. In GaAs0.992N0.008 wires embedded in less hydrogenated barriers, the phonon frequency exhibits an opposite behavior (red shift). Strain, disorder, phonon localization effects induced by H-irradiation on the GaAs-like phonon frequency are discussed and related to different types of N-H complexes formed in the hydrogenated barriers. It is shown that the red (blue) character of the frequency shift is related to the dominant N-2H (N-3H) type of complexes. Moreover, for specific experimental conditions, an all-optical determination of the uniaxial strain field is obtained. This may improve the design of recently presented devices that exploit the correlation between uniaxial stress and the degree of polarization of photoluminescence.

  13. Neutron induced reactions II: (n,x) reactions on medium and heavy nuclei

    International Nuclear Information System (INIS)

    Cindro, N.

    1976-01-01

    Recent interest in (n,x) reactions in the MeV and above range of energies is concentrated on two main subjects: the mechanism of nucleon emission (precompound in particular) and the possible role of clustering in the emission of complex particles. Hence the first two sections of this paper will be devoted to these two subjects. In the last section some other subjects that have recently emerged in the field are discussed

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

    Directory of Open Access Journals (Sweden)

    Carlos F. Liriano-Jorge

    2014-01-01

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

  15. Study the target effect on the structural, surface and optical properties of TiO2 thin film fabricated by RF sputtering method

    Science.gov (United States)

    Vyas, Sumit; Tiwary, Rohit; Shubham, Kumar; Chakrabarti, P.

    2015-04-01

    The effect of target (Ti metal target and TiO2 target) on Titanium Dioxide (TiO2) thin films grown on ITO coated glass substrate by RF magnetron sputtering has been investigated. A comparative study of both the films was done in respect of crystalline structure, surface morphology and optical properties by using X-ray diffractometer (XRD), Atomic Force Microscopy (AFM) studies and ellipsometric measurements. The XRD results confirmed the crystalline structure and indicated that the deposited films have the intensities of anatase phase. The surface morphology and roughness values indicated that the film using Ti metal target has a smoother surface and densely packed with grains as compared to films obtained using TiO2 target. A high transmission in the visible region, and direct band gap of 3.67 eV and 3.75 eV for films derived by using Ti metal and TiO2 target respectively and indirect bandgap of 3.39 eV for the films derived from both the targets (Ti metal and TiO2 target) were observed by the ellipsometric measurements.

  16. Solvothermal fabrication of TiO2/sepiolite composite gel with exposed {0 0 1} and {1 0 1} facets and its enhanced photocatalytic activity

    Science.gov (United States)

    Liu, Ruirui; Ji, Zhijiang; Wang, Jing; Zhang, Jinjun

    2018-05-01

    A novel TiO2/sepiolite composite gel (TiSG) was fabricated in the presence of cetyltrimethylammonium bromide (CTAB) through a simple solvothermal reaction in an acetic acid-water solvent. A homogeneous anchoring of TiO2 nanoparticles with exposed {0 0 1} and {1 0 1} facets on sepiolite nanofibers was achieved. CTAB content, solvothermal temperature/time, and HAc content play crucial roles in the morphological and facet formation of TiSG. A possible mechanism for the formation of TiSG was further proposed. CTAB as capping/shape-controlling agent can strongly bind to the more reactive (0 0 1) facet of TiO2 and then mitigate the thermodynamically favored (0 0 1) plane growth. Eventually, the truncated octahedral TiO2 was obtained by controlling the growth rates in 〈0 0 1〉 and 〈1 0 1〉 directions. Sepiolite as a cross-linking agent provides sufficient crosslinking sites for TiO2 to induce three-dimensional (3D) network formation, thereby generating the composite gel. The synthesized TiSG samples were then used as photocatalysts, which exhibited increased methyl orange removal under UV-vis light (350-780 nm) by the synergistic effect of adsorption and in-situ photocatalytic degradation as compared to P25 and bare TiO2. The excellent photocatalytic performance of TiSG was mainly ascribed to the formations of 3D gel structure and surface heterojunctions between (0 0 1) and (1 0 1) facets.

  17. Facile fabrication of p-n heterojunctions for Cu2O submicroparticles deposited on anatase TiO2 nanobelts

    International Nuclear Information System (INIS)

    Li, Li; Lei, Jingguo; Ji, Tianhao

    2011-01-01

    Graphical abstract: Cu 2 O particle-deposited TiO 2 nanobelts with p-n semiconductor heterojunction structure were successfully prepared via two-step preparation process, and their visible-light photodegradation activities of Rhodamine B were investigated in detail. Highlights: → Cu 2 O particle-deposited TiO 2 nanobelts mainly with diameters in a range of 200-400 nm were successfully prepared. → The amount of Cu 2 O particles deposited on TiO 2 nanobelts can be tuned. → The composite structure with Cu 2 O particles and TiO 2 nanobelts exhibits p-n semiconductor heterojunction performance. → Photocatalytic properties of such composites. -- Abstract: In this paper, Cu 2 O particle-deposited TiO 2 nanobelts with p-n semiconductor heterojunction structure were successfully prepared via a two-step preparation process to investigate electron-transfer performance between p-type Cu 2 O and n-type TiO 2 . Various measurement results confirm that the amount of pure Cu 2 O submicroparticles, with diameters within the range of 200-400 nm and deposited on the surface of TiO 2 nanobelts, can be controlled, and that the purity of Cu 2 O is heavily affected by reaction time. Visible-light photodegradation activities of Rhodamine B show that photocatalysts have little or no photocatalytic activities mainly due to their p-n heterojunction structure, indicating that there hardly appears any electron-transfer from Cu 2 O to TiO 2 .

  18. Fabrication of TiO2-modified polytetrafluoroethylene ultrafiltration membranes via plasma-enhanced surface graft pretreatment

    Science.gov (United States)

    Qian, Yingjia; Chi, Lina; Zhou, Weili; Yu, Zhenjiang; Zhang, Zhongzhi; Zhang, Zhenjia; Jiang, Zheng

    2016-01-01

    Surface hydrophilic modification of polymer ultrafiltration membrane using metal oxide represents an effective yet highly challenging solution to improve water flux and antifouling performance. Via plasma-enhanced graft of poly acryl acid (PAA) prior to coating TiO2, we successfully fixed TiO2 functional thin layer on super hydrophobic polytetrafluoroethylene (PTFE) ultrafiltration (UF) membranes. The characterization results evidenced TiO2 attached on the PTFE-based UF membranes through the chelating bidentate coordination between surface-grafted carboxyl group and Ti4+. The TiO2 surface modification may greatly reduce the water contact angle from 115.8° of the PTFE membrane to 35.0° without degradation in 30-day continuous filtration operations. The novel TiO2/PAA/PTFE membranes also exhibited excellent antifouling and self-cleaning performance due to the intrinsic hydrophilicity and photocatalysis properties of TiO2, which was further confirmed by the photo-degradation of MB under Xe lamp irradiation.

  19. Influence of annealing on X-ray radiation sensing properties of TiO2 thin film

    Science.gov (United States)

    Sarma, M. P.; Kalita, J. M.; Wary, G.

    2018-03-01

    A recent study shows that the titanium dioxide (TiO2) thin film synthesised by a chemical bath deposition technique is a very useful material for the X-ray radiation sensor. In this work, we reported the influence of annealing on the X-ray radiation detection sensitivity of the TiO2 film. The films were annealed at 333 K, 363 K, 393 K, 473 K, and 573 K for 1 hour. Structural analyses showed that the microstrain and dislocation density decreased whereas the average crystallite size increased with annealing. The band gap of the films also decreased from 3.26 eV to 3.10 eV after annealing. The I-V characteristics record under the dark condition and under the X-ray irradiation showed that the conductivity increased with annealing. The influence of annealing on the detection sensitivity was negligible if the bias voltage applied across the films was low (within 0.2 V‒1.0 V). At higher bias voltage (>1.0 V), the contribution of electrons excited by X-ray became less significant which affected the detection sensitivity.

  20. Review on the Photocatalyst Coatings of TiO2: Fabrication by Mechanical Coating Technique and Its Application

    Directory of Open Access Journals (Sweden)

    Yun Lu

    2015-07-01

    Full Text Available This review presents the latest results of studies directed at photocatalyst coatings of titanium dioxide (TiO2 prepared by mechanical coating technique (MCT and its application. Compared with traditional coating techniques, MCT is a simple, low cost and useful coating formation process, which is proposed and developed based on mechanical frictional wear and impacts between substrate materials and metal powder particles in the bowl of planetary ball mill. The formation process of the metal coatings in MCT includes four stages: The nucleation by adhesion, the formation and coalescence of discrete islands, formation and thickening of continuous coatings, exfoliation of continuous coatings. Further, two-step MCT was developed based on the MCT concept for preparing composite coatings on alumina (Al2O3 balls. This review also discusses the influence on the fabrication of photocatalyst coatings after MCT and improvement of its photocatalytic activity: oxidation conditions, coating materials, melt salt treatment. In this review, the oxidation conditions had been studied on the oxidation temperature of 573 K, 673 K, 773 K, 873 K, 973 K, 1173 K and 1273 K, the oxidation time of 0.5 h, 1 h, 3 h, 10 h, 15 h, 20 h, 30 h, 40 h, and 50 h. The photocatalyst coatings showed the highest photocatalytic activity with the oxidation condition of 1073 K for 15 h. The metal powder of Ti, Ni and Cr had been used as the coating materials. The composite metal powder could affect the surface structure and photocatalytic activity. On the other hand, the melt salt treatment with KNO3 is an effective method to form the nano-size structure and enhance photocatalytic activity, especially under visible light.

  1. Effect of Annealing Process on CH3NH3PbI3-XClX Film Morphology of Planar Heterojunction Perovskite Solar Cells with Optimal Compact TiO2 Layer

    Directory of Open Access Journals (Sweden)

    Dan Chen

    2017-01-01

    Full Text Available The morphology of compact TiO2 film used as an electron-selective layer and perovskite film used as a light absorption layer in planar perovskite solar cells has a significant influence on the photovoltaic performance of the devices. In this paper, the spin coating speed of the compact TiO2 is investigated in order to get a high-quality film and the compact TiO2 film exhibits pinhole- and crack-free films treated by 2000 rpm for 60 s. Furthermore, the effect of annealing process, including annealing temperature and annealing program, on CH3NH3PbI3-XClX film morphology is studied. At the optimal annealing temperature of 100°C, the CH3NH3PbI3-XClX morphology fabricated by multistep slow annealing method has smaller grain boundaries and holes than that prepared by one-step direct annealing method, which results in the reduction of grain boundary recombination and the increase of Voc. With all optimal procedures, a planar fluorine-doped tin oxide (FTO substrate/compact TiO2/CH3NH3PbI3-XClX/Spiro-MeOTAD/Au cell is prepared for an active area of 0.1 cm2. It has achieved a power conversion efficiency (PCE of 14.64%, which is 80.3% higher than the reference cell (8.12% PCE without optimal perovskite layer. We anticipate that the annealing process with optimal compact TiO2 layer would possibly become a promising method for future industrialization of planar perovskite solar cells.

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

    Directory of Open Access Journals (Sweden)

    Dang Yu

    2013-01-01

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

  3. Template-Directed Fabrication of Anatase TiO2 Hollow Nanoparticles and Their Application in Photocatalytic Degradation of Methyl Orange

    Institute of Scientific and Technical Information of China (English)

    Jie Chang; Wenjian Zhang; Chunyan Hong

    2017-01-01

    Polymerization-induced self-assembly (PISA) was used to fabricate polymeric nanoparticles via reversible addition-fragmentation chain transfer (RAFT) dispersion polymerization of benzyl methacrylate (BzMA) using diblock copolymer poly(glycerol monomethacrylate)-block-poly(2-dimethylaminoethyl methacrylate) (PGMMA-PDMAEMA-CTA) as the macro RAFT agent.The dispersion of polymeric nanoparticles with a final concentration of about 210 mg/g (solid content of 21%) was obtained via this efficient method (PISA).The resultant polymeric nanoparticles consisting of corona-shell-core three layers with weak polyelectrolyte PDMAEMA as the shell were used as sacrificial template to fabricate TiO2 hollow nanoparticles.The negatively charged titanium precursor was absorbed into the PDMAEMA shell via the electrostatic interaction,and hydrolyzed to form polymer/TiO2 hybrid nanoparticles.Anatase TiO2 hollow nanoparticles were formed after removing the polymeric templates by calcination at 550 ℃.The experiments of photocatalytic degradation of methyl orange showed that the resultant anatase TiO2 hollow nanoparticles had high photocatalytic activity and good reusability.

  4. Method of spectra parametrization of (n, x) and (n, nx) reactions induced by DT-neutrons

    International Nuclear Information System (INIS)

    Aleksandrov, D.V.; Kovrigin, B.S.

    1980-01-01

    A method for parmetrization of experimental spectra has been developed for more convenient carrying out a process of separating competing mechanisms contributions in spectra of the (n, x) and (n, nx) reactions induced with DT neutrons. Differential cross sections of competing partial processes are used. as expanding coefficients. Model spectra may be represented in the form of tabulated-given functions calculated separately from formulae of any complexity degree. Fit of model expressions is performed by the least square method (lsm). Step-by-step algorithm of nonlinear optimization is used for search for lsm- evaluations of theoretical models parameters [ru

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

    Science.gov (United States)

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

    2018-06-01

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

  6. Analysis of Ti valence states in resistive switching regions of a rutile TiO2‑ x four-terminal memristive device

    Science.gov (United States)

    Yamaguchi, Kengo; Takeuchi, Shotaro; Tohei, Tetsuya; Ikarashi, Nobuyuki; Sakai, Akira

    2018-06-01

    We have performed Ti valence state analysis of our four-terminal rutile TiO2‑ x single-crystal memristors using scanning transmission electron microscopy–electron energy loss spectroscopy (STEM–EELS). Analysis of Ti-L2,3 edge EELS spectra revealed that the electrocolored region formed by the application of voltage includes a valence state reflecting highly reduced TiO2‑ x due to the accumulation of oxygen vacancies. Such a valence state mainly exists within ∼50 nm from the crystal surface and extends along specific crystal directions. These electrically reduced surface layers are considered to directly contribute to the resistive switching (RS) in the four-terminal device. The present results add new insights into the microscopic mechanisms of the RS phenomena and should contribute to further development and improvements of TiO2‑ x based memristive devices.

  7. Fabrication of transparent TiO2 nanotube-based photoanodes for CdS/CdTe quantum co-sensitized solar cells

    Science.gov (United States)

    Gualdrón-Reyes, A. F.; Cárdenas-Arenas, A.; Martínez, C. A.; Kouznetsov, V. V.; Meléndez, A. M.

    2017-01-01

    In order to fabricate a solar cell, ordered TiO2 nanotube (TNT) arrays were prepared by double anodization. TNT arrays with variable lengths were obtained by changing the duration of the anodizing process of up to 3h. TNT membranes were transferred to indium tin oxide substrates and attached with a B-TiO2 sol. TNT photoanode with the best photoelectrochemical performance was sensitized with CdS by SILAR method. On other hand, CdTe quantum dots prepared via colloidal synthesis were deposited on TNT photoanodes for 2h, 4h and 6h. In addition, TNT/CdS was loaded with CdTe quantum dots for 4 h. Morphology and chemical modification of TiO2 were characterized by FESEM and XPS, while their photoelectrochemical performance was measured by open-circuit photopotential and photovoltammetry under visible light. TiO2 nanotubes grown during 2.5h showed the highest photocurrent due to presence of Ti3+ donor states by N and F co-doping, increasing the number of photogenerated electrons transported to back collector. TNT/CdS/CdTe photoanode reach the highest conversion efficiency under AM 1.5G simulated solar illumination.

  8. Sequential Dip-spin Coating Method: Fully Infiltration of MAPbI 3-x Cl x into Mesoporous TiO 2 for Stable Hybrid Perovskite Solar Cells

    KAUST Repository

    Kim, Woochul

    2017-05-31

    Organic-inorganic hybrid perovskite solar cells (PSCs) have reached a power conversion efficiency of 22.1% in a short period (∼7 years), which has been obtainable in silicon-based solar cells for decades. The high power conversion efficiency and simple fabrication process render perovskite solar cells as potential future power generators, after overcoming the lack of long-term stability, for which the deposition of void-free and pore-filled perovskite films on mesoporous TiO2 layers is the key pursuit. In this research, we developed a sequential dip-spin coating method in which the perovskite solution can easily infiltrate the pores within the TiO2 nanoparticulate layer, and the resultant film has large crystalline grains without voids between them. As a result, a higher short circuit current is achieved owing to the large interfacial area of TiO2/perovskite, along with enhanced power conversion efficiency, compared to the conventional spin coating method. The as-made pore-filled and void-free perovskite film avoids intrinsic moisture and air and can effectively protect the diffusion of degradation factors into the perovskite film, which is advantageous for the long-term stability of PSCs.

  9. Preparation and Photocatalytic Property of Sr(Zr1-xYx)O3/TiO2/CdS heterojunction photocatalysts

    International Nuclear Information System (INIS)

    Chen Yonggang; Liu Suwen; Zhang Haiping; Xiu Zhiliang; Yu Xiaojun; Wang Enhua; Li Tanggang

    2010-01-01

    A novel composite heterojunction photocatalysts Sr(Zr 1-x Y x )O 3 /TiO 2 /CdS was prepared by sol-gel combustion method. Its photoatalytic properties under visible light were investigated through degradation of methyl orange. XRD, SEM, Uv-Vis and PL techniques were used to characterize the structure and optical properties of the sample. The results showed that the photocatalytic activity of prepared composite photocatalysts under visible light is 2.85 times of that of pure TiO 2 .

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

    International Nuclear Information System (INIS)

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

    2013-01-01

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

  11. An easy-to-fabricate low-temperature TiO2 electron collection layer for high efficiency planar heterojunction perovskite solar cells

    Directory of Open Access Journals (Sweden)

    B. Conings

    2014-08-01

    Full Text Available Organometal trihalide perovskite solar cells arguably represent the most auspicious new photovoltaic technology so far, as they possess an astonishing combination of properties. The impressive and brisk advances achieved so far bring forth highly efficient and solution processable solar cells, holding great promise to grow into a mature technology that is ready to be embedded on a large scale. However, the vast majority of state-of-the-art perovskite solar cells contains a dense TiO2 electron collection layer that requires a high temperature treatment (>450 °C, which obstructs the road towards roll-to-roll processing on flexible foils that can withstand no more than ∼150 °C. Furthermore, this high temperature treatment leads to an overall increased energy payback time and cumulative energy demand for this emerging photovoltaic technology. Here we present the implementation of an alternative TiO2 layer formed from an easily prepared nanoparticle dispersion, with annealing needs well within reach of roll-to-roll processing, making this technology also appealing from the energy payback aspect. Chemical and morphological analysis allows to understand and optimize the processing conditions of the TiO2 layer, finally resulting in a maximum obtained efficiency of 13.6% for a planar heterojunction solar cell within an ITO/TiO2/CH3NH3PbI3-xClxpoly(3-hexylthiophene/Ag architecture.

  12. Photodecomposition of volatile organic compounds using TiO2 nanoparticles.

    Science.gov (United States)

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

    2007-06-01

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

  13. Fabrication of Fiber Bragg Grating Coating with TiO2 Nanostructured Metal Oxide for Refractive Index Sensor

    Directory of Open Access Journals (Sweden)

    Shaymaa Riyadh Tahhan

    2017-01-01

    Full Text Available To increase the sensitivity of biosensor a new approach using an optical fiber Bragg grating (FBG coated with a suitable nanostructured metal oxide (NMO is proposed which is costly effective compared to other biosensors. Bragg grating was written on a D-shaped optical fiber by phase mask method using a 248 nm KrF excimer laser for a 5 min exposure time producing a grating with a period of 528 nm. Titanium dioxide (TiO2 nanostructured metal oxide was coated over the fiber for the purpose of increasing its sensing area. The etched D-shaped FBG was then coated with 312 nm thick TiO2 nanostructured layer to ensure propagating the radiation modes within the core. The final structure was used to sense deionized water and saline. The etched D-shaped FBG original sensitivity before coating to air-deionized water and to air-saline was 0.314 nm/riu and 0.142 nm/riu, respectively. After coating the sensitivity became 1.257 nm/riu for air-deionized water and 0.857 nm/riu for air-saline.

  14. 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.

  15. Fabrication of ridge waveguide structure from photosensitive TiO2/ormosil hybrid films by using an ultraviolet soft imprint technique

    International Nuclear Information System (INIS)

    Zhang, Xuehua; Que, Wenxiu; Chen, Jing; Gao, Tianxi; Hu, Jiaxing; Liu, Weiguo

    2013-01-01

    Photosensitive TiO 2 /organically modified silane hybrid films were prepared by combining a low-temperature sol–gel process with a spin-coating technique. Optical properties and photochemical activities of the as-prepared hybrid sol–gel films under different UV irradiation time were characterized and monitored by prism coupling technique, UV–visible spectroscopy, and Fourier transform infrared spectroscopy. Surface morphology of the hybrid films was also observed by an atomic force microscopy. Advantages for fabrication of ridge waveguide structure based on the photosensitive hybrid films were demonstrated by an ultraviolet soft imprint technique. Effects of imprint force, imprint time, and UV irradiation time on high replication fidelity of the ridge waveguide structure were also investigated. An altitude replication fidelity of 99.7% can be obtained when the imprint force of 2 MPa, imprint time of 30 min and UV irradiation time of 45 min were chosen. Scanning electron microscopy and surface profiler were used to characterize the morphological and surface profile properties of the as fabricated ridge waveguide structure. Results indicate that the as-prepared photosensitive hybrid materials have great applicability for the fabrication of micro-optical elements and advantage as the imprint layer under the ultraviolet soft imprint technique. - Highlights: ► Photosensitive TiO 2 /ormosil hybrid film is prepared by a sol–gel process. ► Optical properties of the films change a little with UV exposure time. ► Photo-chemical property of the film changes a lot with UV exposure time. ► The imprint force and time, and the UV exposure time affect the imprint fidelity. ► A fidelity value of 99.7% is obtained under an optimized condition

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

    International Nuclear Information System (INIS)

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

    2016-01-01

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

  17. 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-.

  18. Hydrogen-Etched TiO2−x as Efficient Support of Gold Catalysts for Water–Gas Shift Reaction

    Directory of Open Access Journals (Sweden)

    Li Song

    2018-01-01

    Full Text Available Hydrogen-etching technology was used to prepare TiO2−x nanoribbons with abundant stable surface oxygen vacancies. Compared with traditional Au-TiO2, gold supported on hydrogen-etched TiO2−x nanoribbons had been proven to be efficient and stable water–gas shift (WGS catalysts. The disorder layer and abundant stable surface oxygen vacancies of hydrogen-etched TiO2−x nanoribbons lead to higher microstrain and more metallic Au0 species, respectively, which all facilitate the improvement of WGS catalytic activities. Furthermore, we successfully correlated the WGS thermocatalytic activities with their optoelectronic properties, and then tried to understand WGS pathways from the view of electron flow process. Hereinto, the narrowed forbidden band gap leads to the decreased Ohmic barrier, which enhances the transmission efficiency of “hot-electron flow”. Meanwhile, the abundant surface oxygen vacancies are considered as electron traps, thus promoting the flow of “hot-electron” and reduction reaction of H2O. As a result, the WGS catalytic activity was enhanced. The concept involved hydrogen-etching technology leading to abundant surface oxygen vacancies can be attempted on other supported catalysts for WGS reaction or other thermocatalytic reactions.

  19. The electronic band structures of InNxAs1-x, InNxSb1-x and InAsxSb1-x alloys

    International Nuclear Information System (INIS)

    Mohammad, Rezek; Katircioglu, Senay

    2009-01-01

    The band gap bowings of InN x As 1-x , InN x Sb 1-x , and InAs x Sb 1-x alloys defined by the optimized lattice constants are investigated using empirical tight binding (ETB) method. The present ETB energy parameters which take the nearest neighbor interactions into account with sp 3 d 2 basis are determined to be sufficient to provide a typical feature for the band gap bowings of the alloys. The band gap bowing parameter is found to be relatively large in both InN x As 1-x and InN x Sb 1-x compared to InAs x Sb 1-x alloys. Moreover, the variation of the fundamental band gaps of InN x Sb 1-x alloys is sharper than that of InN x As 1-x alloys for small concentrations of N. Besides, a small amount of nitrogen is determined to be more effective in InN x Sb 1-x than in InN x As 1-x alloys to decrease the corresponding effective masses of the electrons around Γ points

  20. 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.

  1. Improved conversion efficiency of dye sensitized solar cell using Zn doped TiO_2-ZrO_2 nanocomposite

    International Nuclear Information System (INIS)

    Tomar, Laxmi J.; Bhatt, Piyush J.; Desai, Rahul K.; Chakrabarty, B. S.; Panchal, C. J.

    2016-01-01

    TiO_2-ZrO_2 and Zn doped TiO_2-ZrO_2 nanocomposites were prepared by hydrothermal method for dye sensitized solar cell (DSSC) application. The structural and optical properties were investigated by X –ray diffraction (XRD) and UV-Visible spectroscopy respectively. XRD results revealed the formation of material in nano size. The average crystallite size is 22.32 nm, 17.41 nm and 6.31 nm for TiO_2, TiO_2-ZrO_2 and Zn doped TiO_2-ZrO_2 nanocomposites respectively. The optical bandgap varies from 2.04 eV to 3.75 eV. Dye sensitized solar cells were fabricated using the prepared material. Pomegranate juice was used as a sensitizer and graphite coated conducting glass plate was used as counter electrode. The I – V characteristics were recorded to measure photo response of DSSC. Photovoltaic parameter like open circuit voltage, power conversion efficiency, and fill factor were evaluated for fabricated solar cell. The power conversion efficiency of DSSC fabricated with TiO_2, TiO_2-ZrO_2 and Zn doped TiO_2-ZrO_2 nanocomposites were found 0.71%, 1.97% and 4.58% respectively.

  2. Improved conversion efficiency of dye sensitized solar cell using Zn doped TiO2-ZrO2 nanocomposite

    Science.gov (United States)

    Tomar, Laxmi J.; Bhatt, Piyush J.; Desai, Rahul K.; Chakrabarty, B. S.; Panchal, C. J.

    2016-05-01

    TiO2-ZrO2 and Zn doped TiO2-ZrO2 nanocomposites were prepared by hydrothermal method for dye sensitized solar cell (DSSC) application. The structural and optical properties were investigated by X -ray diffraction (XRD) and UV-Visible spectroscopy respectively. XRD results revealed the formation of material in nano size. The average crystallite size is 22.32 nm, 17.41 nm and 6.31 nm for TiO2, TiO2-ZrO2 and Zn doped TiO2-ZrO2 nanocomposites respectively. The optical bandgap varies from 2.04 eV to 3.75 eV. Dye sensitized solar cells were fabricated using the prepared material. Pomegranate juice was used as a sensitizer and graphite coated conducting glass plate was used as counter electrode. The I - V characteristics were recorded to measure photo response of DSSC. Photovoltaic parameter like open circuit voltage, power conversion efficiency, and fill factor were evaluated for fabricated solar cell. The power conversion efficiency of DSSC fabricated with TiO2, TiO2-ZrO2 and Zn doped TiO2-ZrO2 nanocomposites were found 0.71%, 1.97% and 4.58% respectively.

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

    Science.gov (United States)

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

    2017-12-01

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

  4. Preparation and characterization of doped TiO2 nanofibers by coaxial electrospining combined with sol–gel process

    International Nuclear Information System (INIS)

    Tong, Haixia; Tao, Xican; Wu, Daoxin; Zhang, Xiongfei; Li, Dan; Zhang, Ling

    2014-01-01

    Graphical abstract: The surface of the precursor of Fe/TiO 2 nanofibers are smoother than that of Fe /TiO 2 nanofibers. After calcined at 500 °C, the tubers on the surface of the nanofibers become more obvious, and which also provides a direct proof for the dopant of Fe element. -- Highlights: • N, Fe, and W doped TiO 2 nanofibers have been fabricated by coaxial electrospining. • The dopant has obvious influences on the surface topographies and crystal structures. • Fe doping can make remarkable topography changes and easy formation of rutile TiO 2 . • The maximum doping amount of W in TiO 2 nanofibers is less than 10% under 500 °C. -- Abstract: N, Fe, and W doped TiO 2 nanofibers were fabricated by coaxial electrospining and directly annealing polyvinylpyrrolidone (PVP)/Tetrabutyl titanate (TBT) composite nanofibers. The crystal structure, morphology, and surface composition of the doped TiO 2 nanofibers were investigated by the X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) respectively. The results show that the dopants have different influence on the surface topographies, the crystal structures and the transformation of anatase to rutile of TiO 2 nanofibers. Fe dopant promotes bigger influence on topographies, phase transformation and crystallite growth of TiO 2 nanofibers than that of either N or W dopant

  5. Thiourea-Modified TiO2 Nanorods with Enhanced Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Xiaofeng Wu

    2016-02-01

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

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

    Science.gov (United States)

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

    2018-01-01

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

  7. A Brown Mesoporous TiO2-x /MCF Composite with an Extremely High Quantum Yield of Solar Energy Photocatalysis for H2 Evolution.

    Science.gov (United States)

    Xing, Mingyang; Zhang, Jinlong; Qiu, Bocheng; Tian, Baozhu; Anpo, Masakazu; Che, Michel

    2015-04-24

    A brown mesoporous TiO2-x /MCF composite with a high fluorine dopant concentration (8.01 at%) is synthesized by a vacuum activation method. It exhibits an excellent solar absorption and a record-breaking quantum yield (Φ = 46%) and a high photon-hydrogen energy conversion efficiency (η = 34%,) for solar photocatalytic H2 production, which are all higher than that of the black hydrogen-doped TiO2 (Φ = 35%, η = 24%). The MCFs serve to improve the adsorption of F atoms onto the TiO2 /MCF composite surface, which after the formation of oxygen vacancies by vacuum activation, facilitate the abundant substitution of these vacancies with F atoms. The decrease of recombination sites induced by high-concentration F doping and the synergistic effect between lattice Ti(3+)-F and surface Ti(3+)-F are responsible for the enhanced lifetime of electrons, the observed excellent absorption of solar light, and the photocatalytic production of H2 for these catalysts. The as-prepared F-doped composite is an ideal solar light-driven photocatalyst with great potential for applications ranging from the remediation of environmental pollution to the harnessing of solar energy for H2 production. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    International Nuclear Information System (INIS)

    Du, Yuanyuan; Zheng, Pengwu

    2014-01-01

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

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

    International Nuclear Information System (INIS)

    Cai Fengshi; Yuan Zhihao; Duan Yueqing; Bie Lijian

    2011-01-01

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

  10. Preparation of an orthodontic bracket coated with an nitrogen-doped TiO(2-x)N(y) thin film and examination of its antimicrobial performance.

    Science.gov (United States)

    Cao, Baocheng; Wang, Yuhua; Li, Na; Liu, Bin; Zhang, Yingjie

    2013-01-01

    A bracket coated with a nitrogen-doped (N-doped) TiO(2-x)N(y) thin film was prepared using the RF magnetron sputtering method. The physicochemical properties of the thin film were measured using X-ray diffraction and energy-dispersive X-ray spectrometry, while the antimicrobial activity of the bracket against common oral pathogenic microbes was assessed on the basis of colony counts. The rate of antimicrobial activity of the bracket coated with nano-TiO(2-x)N(y) thin film against Streptococcus mutans, Lactobacillus acidophilus, Actinomyces viscous, and Candida albicans was 95.19%, 91.00%, 69.44%, and 98.86%, respectively. Scanning electron microscopy showed that fewer microbes adhered to the surface of this newly designed bracket than to the surface of the normal edgewise bracket. The brackets coated with the N-doped TiO(2-x)N(y) thin film showed high antimicrobial and bacterial adhesive properties against normal oral pathogenic bacterial through visible light, which is effective in prevention of enamel demineralization and gingivitis in orthodontic patients.

  11. Fabrication, Modification, and Emerging Applications of TiO2 Nanotube Arrays by Electrochemical Synthesis: A Review

    Directory of Open Access Journals (Sweden)

    Jian-Ying Huang

    2013-01-01

    Full Text Available Titania nanotube arrays (TNAs as a hot nanomaterial have a unique highly ordered array structure and good mechanical and chemical stability, as well as excellent anticorrosion, biocompatible, and photocatalytic performance. It has been fabricated by a facile electrochemical anodization in electrolytes containing small amounts of fluoric ions. In combination with our research work, we review the recent progress of the new research achievements of TNAs on the preparation processes, forming mechanism, and modification. In addition, we will review the potential and significant applications in the photocatalytic degradation of pollutants, solar cells, water splitting, and other aspects. Finally, the existing problems and further prospects of this renascent and rapidly developing field are also briefly addressed and discussed.

  12. Hybridization and bond-orbital components in site-specific X-ray photoelectron spectra of rutile TiO2

    International Nuclear Information System (INIS)

    Woicik, J.C.; Nelson, E.J.; Kronik, Leeor; Jain, Manish; Chelikowsky, James R.; Heskett, D.; Berman, L.E.; Herman, G.S.

    2002-01-01

    We have determined the Ti and O components of the rutile TiO 2 valence band using the method of site-specific x-ray photoelectron spectroscopy. Comparisons with calculations based on pseudopotentials within the local density approximation reveal the hybridization of the Ti 3d, 4s, and 4p states, and the O 2s and 2p states on each site. These chemical effects are observed due to the large differences between the angular-momentum dependent matrix elements of the photoelectron process

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

    International Nuclear Information System (INIS)

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

    2012-01-01

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

  14. Nb and Ta Co-Doped TiO2 Transparent Conductive Thin Films by Magnetron Sputtering: Fabrication, Structure, and Characteristics

    Science.gov (United States)

    Liu, Yang; Peng, Qian; Qiao, Yadong; Yang, Guang

    2018-06-01

    Nb and Ta co-doped anatase titanium dioxide (NTTO) nanocrystalline thin films were deposited on quartz and Si (100) substrates by RF magnetron sputtering. The influence of RF power on the growth, structure, morphology, and properties of the samples are discussed in detail. X-ray diffraction measurements show that the films are polycrystalline with anatase tetragonal structure, which is further confirmed by Raman spectroscopy analysis. Meanwhile, Raman spectroscopy results indicate that the peak width of E g(1) mode, which is directly correlated to the carrier density, changes obviously with RF power. It is found that the substitution of Nb5+ and Ta5+ at Ti site is significantly improved with the increase of RF power from 150 W to 210 W. For the sample deposited at 210 W, the optical transmittance is above 82% in the visible range and the electrical resistivity is as low as 1.3 × 10-3 Ω cm with carrier density of 1.1 × 1021 cm-3 and Hall mobility of 4.5 cm2 V-1 s-1. The optical and electrical properties of NTTO thin films can be compared to those of Nb or Ta doped anatase TiO2. However, co-doping with Nb and Ta gives a possible platform to complement the limitations of each individual dopant.

  15. Copper doped TiO2 nanoparticles characterized by X-ray absorption spectroscopy, total scattering, and powder diffraction--a benchmark structure-property study.

    Science.gov (United States)

    Lock, Nina; Jensen, Ellen M L; Mi, Jianli; Mamakhel, Aref; Norén, Katarina; Qingbo, Meng; Iversen, Bo B

    2013-07-14

    Metal functionalized nanoparticles potentially have improved properties e.g. in catalytic applications, but their precise structures are often very challenging to determine. Here we report a structural benchmark study based on tetragonal anatase TiO2 nanoparticles containing 0-2 wt% copper. The particles were synthesized by continuous flow synthesis under supercritical water-isopropanol conditions. Size determination using synchrotron PXRD, TEM, and X-ray total scattering reveals 5-7 nm monodisperse particles. The precise dopant structure and thermal stability of the highly crystalline powders were characterized by X-ray absorption spectroscopy and multi-temperature synchrotron PXRD (300-1000 K). The combined evidence reveals that copper is present as a dopant on the particle surfaces, most likely in an amorphous oxide or hydroxide shell. UV-VIS spectroscopy shows that copper presence at concentrations higher than 0.3 wt% lowers the band gap energy. The particles are unaffected by heating to 600 K, while growth and partial transformation to rutile TiO2 occur at higher temperatures. Anisotropic unit cell behavior of anatase is observed as a consequence of the particle growth (a decreases and c increases).

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

    Science.gov (United States)

    Jang, JaeMyung; Kwon, TaeYub; Kim, KyoHan

    2008-10-01

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

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

    Science.gov (United States)

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

    2012-09-15

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

  18. Raman scattering and x-ray diffractometry studies of epitaxial TiO2 and VO2 thin films and multilayers on α-Al2O3(11 bar 20)

    International Nuclear Information System (INIS)

    Foster, C.M.; Chiarello, R.P.; Chang, H.L.M.; You, H.; Zhang, T.J.; Frase, H.; Parker, J.C.; Lam, D.J.

    1993-01-01

    Epitaxial thin films of TiO 2 and VO 2 single layers and TiO 2 /VO 2 multilayers were grown on (11 bar 20) sapphire (α-Al 2 O 3 ) substrates using the metalorganic chemical vapor deposition technique and were characterized using Raman scattering and four x-ray diffractometry. X-ray diffraction results indicate that the films are high quality single crystal material with well defined growth plane and small in-plane and out-of-plane mosaic. Single-layer films are shown to obey the Raman selection rules of TiO 2 and VO 2 single crystals. The close adherence to the Raman selection rules indicates the high degree of orientation of the films, both parallel and perpendicular to the growth plane. Selection rule spectra of two and three layer TiO 2 /VO 2 multilayers are dominated by the VO 2 layers with only minimal signature of the TiO 2 layers. Due to the low band gap of semiconducting vanadium dioxide, we attribute the strong signature of the VO 2 layers to resonant enhancement of the VO 2 Raman component accompanied with absorption of the both the incident and scattered laser light from the TiO 2 layers

  19. Luminescence properties of Eu2+-doped MAl2-xSixO4-xNx (M = Ca, Sr, Ba) conversion phosphor for white LED applications

    NARCIS (Netherlands)

    Li, Y.Q.; With, de G.; Hintzen, H.T.J.M.

    2006-01-01

    Undoped and Eu-doped MAl2-xSixO4-2Nx (M = Ca, Sr, Ba) were synthesized by a solid-state reaction method at 1300 - 1400 ¿C under nitrogen-hydrogen atmosphere. The solubility of (SiN)+, in MAl2O4 was determined. Nitrogen can be incorporated into MAl2O4 by replacement of (AlO)+ by (SiN)+, whose amount

  20. Fabrication of hierarchically porous TiO2 nanofibers by microemulsion electrospinning and their application as anode material for lithium-ion batteries

    Directory of Open Access Journals (Sweden)

    Jin Zhang

    2017-06-01

    Full Text Available Titanium dioxide (TiO2 nanofibers have been widely applied in various fields including photocatalysis, energy storage and solar cells due to the advantages of low cost, high abundance and nontoxicity. However, the low conductivity of ions and bulk electrons hinder its rapid development in lithium-ion batteries (LIB. In order to improve the electrochemical performances of TiO2 nanomaterials as anode for LIB, hierarchically porous TiO2 nanofibers with different tetrabutyl titanate (TBT/paraffin oil ratios were prepared as anode for LIB via a versatile single-nozzle microemulsion electrospinning (ME-ES method followed by calcining. The experimental results indicated that TiO2 nanofibers with the higher TBT/paraffin oil ratio demonstrated more axially aligned channels and a larger specific surface area. Furthermore, they presented superior lithium-ion storage properties in terms of specific capacity, rate capability and cycling performance compared with solid TiO2 nanofibers for LIB. The initial discharge and charge capacity of porous TiO2 nanofibers with a TBT/paraffin oil ratio of 2.25 reached up to 634.72 and 390.42 mAh·g−1, thus resulting in a coulombic efficiency of 61.51%; and the discharge capacity maintained 264.56 mAh·g−1 after 100 cycles, which was much higher than that of solid TiO2 nanofibers. TiO2 nanofibers with TBT/paraffin oil ratio of 2.25 still obtained a high reversible capacity of 204.53 mAh·g−1 when current density returned back to 40 mA·g−1 after 60 cycles at increasing stepwise current density from 40 mA·g−1 to 800 mA·g−1. Herein, hierarchically porous TiO2 nanofibers have the potential to be applied as anode for lithium-ion batteries in practical applications.

  1. TiO2 as diffusion barrier at Co/Alq3 interface studied by x-ray standing wave technique

    Science.gov (United States)

    Phatak Londhe, Vaishali; Gupta, A.; Ponpandian, N.; Kumar, D.; Reddy, V. R.

    2018-06-01

    Nano-scale diffusion at the interfaces in organic spin valve thin films plays a vital role in controlling the performance of magneto-electronic devices. In the present work, it is shown that a thin layer of titanium dioxide at the interface of Co/Alq3 can act as a good diffusion barrier. The buried interfaces of Co/Alq3/Co organic spin valve thin film has been studied using x-ray standing waves technique. A planar waveguide is formed with Alq3 layer forming the cavity and Co layers as the walls of the waveguide. Precise information about diffusion of Co into Alq3 is obtained through excitation of the waveguide modes. It is found that the top Co layer diffuses deep into the Alq3 resulting in incorporation of 3.1% Co in the Alq3 layer. Insertion of a 1.7 nm thick barrier layer of TiO2 at Co/Alq3 interface results in a drastic reduction in the diffusion of Co into Alq3 to a value of only 0.4%. This suggests a better performance of organic spin valve with diffusion barrier of TiO2.

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  3. Alcohol solvents evaporation-induced self-assembly synthesis of mesoporous TiO2- x- y C x N y nanoparticles toward visible-light driven photocatalytic activity

    Science.gov (United States)

    Liu, Shou-Heng; Syu, Han-Ren; Wu, Chung-Yi

    2014-12-01

    A one-step solvent evaporation-induced self-assembly (SEISA) process was demonstrated to prepare carbon and nitrogen co-doping mesoporous TiO2 nanoparticles (MesoTiO2- x- y C x N y - S) using an ionic liquid as carbon and nitrogen sources as well as mesoporous template. After the evaporation of different solvents (methanol, ethanol, and isopropanol) and subsequent calcinations at 773 K, the obtained MesoTiO2- x- y C x N y - S samples were systematically characterized by a variety of spectroscopic and analytical techniques, including small- and large-angle X-ray diffraction (XRD), Raman, transmission electron microscopy (TEM), N2 adsorption-desorption isotherms, Fourier transform infrared (FTIR), and X-ray photoelectron (XPS) spectroscopies. The results indicate that the solvents play an essential role on the chemical microstructure, doping elemental states, and photocatalytic performance of catalysts. The MesoTiO2- x- y C x N y -I samples have the lowest band gap of ca. 2.75 eV and strongest absorbance of visible light in the range of 400-600 nm. Among the MesoTiO2- x- y C x N y - S photocatalysts, the MesoTiO2- x- y C x N y -M catalysts show superior photocatalytic activity of hydrogen generation in methanol aqueous solution under visible light irradiation as compared to MesoTiO2- x- y C x N y -E, MesoTiO2- x- y C x N y -I, and commercial Degussa TiO2. This result could be attributed to the moderate C,N co-doping amounts on their developed mesoporous texture (pore size = 8.0 nm) and high surface area (107 m2 g-1) of TiO2 (crystallite size = 9.9 nm) in the MesoTiO2- x- y C x N y -M catalysts.

  4. Characterization of TiO2 Thin Films on Glass Substrate Growth Using DC Sputtering Technique

    International Nuclear Information System (INIS)

    Agus Santoso; Tjipto Sujitno; Sayono

    2002-01-01

    It has been fabricated and characterization a TiO 2 thin films deposited on glass substrate using DC sputtering technique. Fabrication of TiO 2 thin films were carried out at electrode voltage 4 kV, sputtering current 5 mA, vacuum pressure 5 x 10 -4 torr, deposition time 150 minutes, and temperature of the substrate were varied from 150 -350 o C, while as a gas sputter was argon. The results was tested their micro structure using SEM, and crystal structure using XRD and found that the crystal structure of TiO 2 powder before deposited on glass substrate was rutile and anatase with orientation (110) and (200) for anatase and (100) and (111) rutile structure. While the crystal structure which deposited at temperature 150 o C and deposition time 2.5 hours was anatase with orientation (001) and (200). (author)

  5. TiO2 thin-films on polymer substrates and their photocatalytic activity

    International Nuclear Information System (INIS)

    Yang, Jae-Hun; Han, Yang-Su; Choy, Jin-Ho

    2006-01-01

    We have developed dip-coating process for TiO 2 -thin film on polymer substrates (acrylonitrile-butadiene-styrene polymer: ABS, polystyrene: PS). At first, a monodispersed and transparent TiO 2 nano-sol solution was prepared by the controlled hydrolysis of titanium iso-propoxide in the presence of acetylacetone and nitric acid catalyst at 80 deg. C. Powder X-ray diffraction patterns of the dried particles are indicative of crystalline TiO 2 with anatase-type structure. According to the XRD and transmission electron microscopy (TEM) studies, the mean particle size was estimated to be ca. 5 nm. The transparent thin films on ABS and PS substrates were fabricated by dip-coating process by changing the processing variables, such as the number of dip-coating and TiO 2 concentration in nano-sol solution. Scanning electron microscopic (SEM) analysis for the thin film samples reveals that the acetylacetone-modified TiO 2 nano-sol particles are effective for enhancing the interfacial adherence between films and polymeric substrates compared to the unmodified one. Photocatalytic degradation of methylene blue (MB) on the TiO 2 thin-films has also been systematically investigated

  6. Synthesis of mesoporous TiO(2-x)N(x) spheres by template free homogeneous co-precipitation method and their photo-catalytic activity under visible light illumination.

    Science.gov (United States)

    Parida, K M; Naik, Brundabana

    2009-05-01

    The article presents preparation, characterization and catalytic activity evaluation of an efficient nitrogen doped mesoporous titania sphere photo-catalyst for degradation of methylene blue (MB) and methyl orange (MO) under visible light illumination. Nitrogen doped titania was prepared by soft chemical route i.e. template free, slow and controlled homogeneous co-precipitation from titanium oxysulfate sulfuric acid complex hydrate, urea, ethanol and water. The molar composition of TiOSO(4) to urea was varied to prepare different atomic % nitrogen doped titania. Mesoporous anatase TiO(2-x)N(x) spheres with average crystallite size of 10 nm and formation of titanium oxynitride center were confirmed from HRTEM, XRD and XPS study. UV-vis DRS showed a strong absorption in the range of 400-500 nm which supports its use in visible spectrum of light. Nitrogen adsorption-desorption study supports the porous nature of the doped material. All the TiO(2-x)N(x) samples showed higher photo-catalytic activity than Degussa P(25) and undoped mesoporous titania. Sample containing around one atomic % nitrogen showed highest activity among the TiO(2-x)N(x) samples.

  7. Study of TiO2(1 1 0)-p(1x1), p(1x2) and p(1x3) surface structures by impact collision ion scattering spectroscopy (ICISS)

    International Nuclear Information System (INIS)

    Asari, E.; Souda, R.

    2000-01-01

    The surface structure of TiO 2 (1 1 0)-p(1x1), p(1x2) and p(1x3) were studied using impact collision ion scattering spectroscopy (ICISS). We found that (i) the height of bridging oxygen for the p(1x1) is comparative to that of bulk structure, (ii) the p(1x2) surface has the added Ti 2 O 3 unit rows proposed by Onishi et al. and also the oxygen atoms rows between Ti 2 O 3 unit rows and (iii) the p(1x3) surface is constructed with the same added Ti 2 O 3 unit rows as that in the p(1x2) surface, but the bridging oxygen rows exist between the Ti 2 O 3 unit rows

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

    Directory of Open Access Journals (Sweden)

    Jiaoping Cai

    2015-02-01

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

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

    Science.gov (United States)

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

    2015-02-01

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

  10. Photocatalytic decomposition of N2O over TiO2/g-C3N4 photocatalysts heterojunction

    Science.gov (United States)

    Kočí, K.; Reli, M.; Troppová, I.; Šihor, M.; Kupková, J.; Kustrowski, P.; Praus, P.

    2017-02-01

    TiO2/g-C3N4 photocatalysts with the various TiO2/g-C3N4 weight ratios from 1:2 to 1:6 were fabricated by mechanical mixing in water suspension followed by calcination. Pure TiO2 was prepared by thermal hydrolysis and pure g-C3N4 was prepared from commercial melamine by thermal annealing at 620 °C. All the nanocomposites were characterized by X-ray powder diffraction, UV-vis diffuse reflectance spectroscopy, Raman spectroscopy, infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, photoelectrochemical measurements and nitrogen physisorption. The prepared mixtures along with pure TiO2 and g-C3N4 were tested for the photocatalytic decomposition of nitrous oxide under UVC (λ = 254 nm), UVA (λ = 365 nm) and Vis (λ > 400 nm) irradiation. The TiO2/g-C3N4 nanocomposites showed moderate improvement compared to pure g-C3N4 but pure TiO2 proved to be a better photocatalyst under UVC irradiation. However, under UVA irradiation conditions, the photocatalytic activity of TiO2/g-C3N4 (1:2) nanocomposite exhibited an increase compared to pure TiO2. Nevertheless, further increase of g-C3N4 amount leads/led to a decrease in reactivity. These results are suggesting the nanocomposite with the optimal weight ratio of TiO2 and g-C3N4 have shifted absorption edge energy towards longer wavelengths and decreased the recombination rate of charge carriers compared to pure g-C3N4. This is probably due to the generation of heterojunction on the TiO2/g-C3N4 interface.

  11. Crystal and Electronic Structures, Photoluminescence Properties of Eu2+-Doped Novel Oxynitride Ba4Si6O16-3x/2Nx

    Directory of Open Access Journals (Sweden)

    Takashi Takeda

    2010-03-01

    Full Text Available The crystal structure and the photoluminescence properties of novel green Ba4-yEuySi6O16-3x/2Nx phosphors were investigated. The electronic structures of the Ba4Si6O16 host were calculated by first principles pseudopotential method based on density functional theory. The results reveal that the top of the valence bands are dominated by O-2p states hybridized with Ba-6s and Si-3p states, while the conduction bands are mainly determined by Ba-6s states for the host, which is an insulator with a direct energy gap of 4.6 eV at Γ. A small amount of nitrogen can be incorporated into the host to replace oxygen and forms Ba4-yEuySi6O16-3x/2Nx solid solutions crystallized in a monoclinic (space group P21/c, Z = 2 having the lattice parameters a = 12.4663(5 Å, b = 4.6829(2 Å, c = 13.9236(6 Å, and β = 93.61(1°, with a maximum solubility of nitrogen at about x = 0.1. Ba4Si6O16-3x/2Nx:Eu2+ exhibits efficient green emission centered at 515–525 nm varying with the Eu2+ concentration when excited under UV to 400 nm. Furthermore, the incorporation of nitrogen can slightly enhance the photoluminescence intensity. Excitation in the UV-blue spectral range (λexc = 375 nm, the absorption and quantum efficiency of Ba4-yEuySi6O16-3x/2Nx (x = 0.1, y = 0.2 reach about 80% and 46%, respectively. Through further improvement of the thermal stability, novel green phosphor of Ba4-yEuySi6O16-3x/2Nx is promising for application in white UV-LEDs.

  12. Influence of TiO2 Nanocrystals Fabricating Dye-Sensitized Solar Cell on the Absorption Spectra of N719 Sensitizer

    Directory of Open Access Journals (Sweden)

    Puhong Wen

    2012-01-01

    Full Text Available The absorption spectra of N719 sensitizer anchored on the films prepared by TiO2 nanocrystals with different morphology and size were investigated for improving the performance of dye-sensitized solar cell (DSC. We find that the morphology and size of TiO2 nanocrystals can affect the UV-vis and FT-IR spectra of the sensitizer anchored on their surfaces. In particular, the low-energy metal-to-ligand charge-transfer transitions (MLCT band in the visible absorption spectra of N719 is strongly affected, and locations of these MLCT bands revealed larger differences. The results indicate that there is a red shift of MLCT band in the spectra obtained by using TiO2 nanocrystals with long morphology and large size compared to that in solution. And it produced a larger red-shift on the MLCT band after TiO2 nanocrystals with small size mixed with some long nanocrystals. Accordingly, the utilization rate to visible light is increased. This is a reason why the DSC prepared by using such film as a photoelectrode has better performance than before mixing.

  13. Fabrication of Ce/N co-doped TiO_2/diatomite granule catalyst and its improved visible-light-driven photoactivity

    International Nuclear Information System (INIS)

    Chen, Yan; Liu, Kuiren

    2017-01-01

    Highlights: • Ce/N co-doped TiO_2/diatomite granule (CNTD-G) was prepared via sol-gel method. • The optimal doping amount of Ce was determined. • The effects of impurity ions on photodegradation process were studied. • The intermediates generated during photodegradation process were deduced. • The mechanism of photodegradation process was proposed. - Abstract: Eliminating antibiotic remnants in aquatic environment has become one of the hottest topics among current research works. Thus, we prepared Ce, N co-doped TiO_2/diatomite granule (CNTD-G) catalyst to provide a new method. As one typical antibiotics, oxytetracycline (OTC) was selected as the target pollutant to be degradated under visible light irradiation. The carrier diatomite helped the spread of TiO_2 nanoparticles onto its surface, and inhibited their agglomeration. The synergy of Ce and N dopants highly improved the visible-light-driven photoactivity of TiO_2. The optimal doping amount and degradation conditions were determined. Besides, the effects of impurity ions were also investigated, including cations: Ca"2"+, Mg"2"+; or anions: NO_3"−, SO_4"2"− and PO_4"3"−. The intermediates generated during degradation process were studied, and the mechanism of the photodegradation process was proposed. CNTD-G could be easily collected from the reactor, and showed excellent recyclability.

  14. H irradiation effects on the GaAs-like Raman modes in GaAs1-xNx/GaAs1-xNx:H planar heterostructures

    International Nuclear Information System (INIS)

    Giulotto, E.; Geddo, M.; Patrini, M.; Guizzetti, G.; Felici, M.; Capizzi, M.; Polimeni, A.; Martelli, F.; Rubini, S.

    2014-01-01

    The GaAs-like longitudinal optical phonon frequency in two hydrogenated GaAs 1-x N x /GaAs 1-x N x :H microwire heterostructures—with similar N concentration, but different H dose and implantation conditions—has been investigated by micro-Raman mapping. In the case of GaAs 0.991 N 0.009 wires embedded in barriers where GaAs-like properties are recovered through H irradiation, the phonon frequency in the barriers undergoes a blue shift with respect to the wires. In GaAs 0.992 N 0.008 wires embedded in less hydrogenated barriers, the phonon frequency exhibits an opposite behavior (red shift). Strain, disorder, phonon localization effects induced by H-irradiation on the GaAs-like phonon frequency are discussed and related to different types of N-H complexes formed in the hydrogenated barriers. It is shown that the red (blue) character of the frequency shift is related to the dominant N-2H (N-3H) type of complexes. Moreover, for specific experimental conditions, an all-optical determination of the uniaxial strain field is obtained. This may improve the design of recently presented devices that exploit the correlation between uniaxial stress and the degree of polarization of photoluminescence

  15. Study of Sn and Mg doping effects on TiO2/Ge stack structure by combinatorial synthesis

    Science.gov (United States)

    Nagata, Takahiro; Suzuki, Yoshihisa; Yamashita, Yoshiyuki; Ogura, Atsushi; Chikyow, Toyohiro

    2018-04-01

    The effects of Sn and Mg doping of a TiO2 film on a Ge substrate were investigated to improve leakage current properties and Ge diffusion into the TiO2 film. For systematic analysis, dopant-composition-spread TiO2 samples with dopant concentrations of up to 20.0 at. % were fabricated by RF sputtering and a combinatorial method. X-ray photoelectron spectroscopy revealed that the instability of Mg doping of TiO2 at dopant concentrations above 10.5 at. %. Both Sn and Mg dopants reduced Ge diffusion into TiO2. Sn doping enhanced the crystallization of the rutile phase, which is a high-dielectric-constant phase, although the Mg-doped TiO2 film indicated an amorphous structure. Sn-doping indicated systematic leakage current reduction with increasing dopant concentration. Doping at Sn concentrations higher than 16.8 at. % improved the leakage properties (˜10-7 A/cm2 at -3.0 V) and capacitance-voltage properties of metal-insulator-semiconductor (MIS) operation. The Sn doping of TiO2 may be useful for interface control and as a dielectric material for Ge-based MIS capacitors.

  16. LEED-IV study of the rutile TiO2(110)-1x2 surface with a Ti-interstitial added-row reconstruction

    International Nuclear Information System (INIS)

    Blanco-Rey, M.; Mendez, J.; Lopez, M. F.; Roman, E.; Martin-Gago, J. A.; Andres, P. L. de; Abad, J.; Rogero, C.

    2007-01-01

    Upon sputtering and annealing in UHV at ∼1000 K, the rutile TiO 2 (110) surface undergoes a 1x1→1x2 phase transition. The resulting 1x2 surface is Ti rich, formed by strands of double Ti rows as seen on scanning tunneling microscopic images, but its detailed structure and composition have been subject to debate in the literature for years. Recently, Park et al. [Phys. Rev. Lett. 96, 226105 (2006)] have proposed a model where Ti atoms are located on interstitial sites with Ti 2 O stoichiometry. This model, when it is analyzed using LEED-IV data [Phys. Rev. Lett. 96, 0055502 (2006)], does not yield an agreement between theory and experiment as good as the previous best fit for Onishi and Iwasawa's model for the long-range 1x2 reconstruction. Therefore, the Ti 2 O 3 added row is the preferred one from the point of view low-energy electron diffraction

  17. 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

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

    Science.gov (United States)

    Pathak, Pawan

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

  19. Fabrication of Ce/N co-doped TiO2/diatomite granule catalyst and its improved visible-light-driven photoactivity.

    Science.gov (United States)

    Chen, Yan; Liu, Kuiren

    2017-02-15

    Eliminating antibiotic remnants in aquatic environment has become one of the hottest topics among current research works. Thus, we prepared Ce, N co-doped TiO 2 /diatomite granule (CNTD-G) catalyst to provide a new method. As one typical antibiotics, oxytetracycline (OTC) was selected as the target pollutant to be degradated under visible light irradiation. The carrier diatomite helped the spread of TiO 2 nanoparticles onto its surface, and inhibited their agglomeration. The synergy of Ce and N dopants highly improved the visible-light-driven photoactivity of TiO 2 . The optimal doping amount and degradation conditions were determined. Besides, the effects of impurity ions were also investigated, including cations: Ca 2+ , Mg 2+ ; or anions: NO 3 - , SO 4 2- and PO 4 3- . The intermediates generated during degradation process were studied, and the mechanism of the photodegradation process was proposed. CNTD-G could be easily collected from the reactor, and showed excellent recyclability. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. 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)

  1. Multifunctionality in coating films including Nb-doped TiO2 and Cs x WO3: near infrared shielding and photocatalytic properties

    Science.gov (United States)

    Asakura, Yusuke; Anada, Yuto; Hamanaka, Ryo; Sato, Tsugio; Katsumata, Ken-ichi; Wu, Xiaoyong; Yin, Shu

    2018-06-01

    Various types of coating films were obtained from hydrothermally synthesized Nb-doped TiO2 (NTO) and Cs x WO3 (CWO) nanoparticles. The coating films possessed multifunctionality including near infrared (NIR) absorption and photocatalysis abilities. The NTO and CWO nanoparticles were synthesized by a unique solvothermal reaction in which water induced by an esterification reaction between alcohol and carboxylic acid can act as a hydrolyzing agent for metal precursors. NTO was synthesized by the unique solvothermal reaction for the first time. The reaction accompanied by the reduction of Ti4+ to Ti3+ led to the formation of nanoparticles with both NIR absorption and photocatalytic properties. The effect of the ethanol–acetic acid ratio on the morphology of the obtained NTO was investigated, and the larger amount of acetic acid led to a larger nanoparticle size, indicating the size controllability. The two types of coating film, including CWO and NTO nanoparticles, were obtained for comparison: (1) coexistent coating film: one side of the quartz glass was coated with a dispersion, including both CWO and NTO nanoparticles, and (2) double-sided coating film: a quartz glass coated with a CWO dispersion on one side and an NTO dispersion on the other side. The double-sided coating led to higher multifunctionality. Furthermore, the optimized condition for the double-sided coating was investigated by using various NTO particles obtained using different ethanol–acetic acid ratios.

  2. Impact of ultra-thin Al2O3-y layers on TiO2-x ReRAM switching characteristics

    Science.gov (United States)

    Trapatseli, Maria; Cortese, Simone; Serb, Alexander; Khiat, Ali; Prodromakis, Themistoklis

    2017-05-01

    Transition metal-oxide resistive random access memory devices have demonstrated excellent performance in switching speed, versatility of switching and low-power operation. However, this technology still faces challenges like poor cycling endurance, degradation due to high electroforming (EF) switching voltages and low yields. Approaches such as engineering of the active layer by doping or addition of thin oxide buffer layers have been often adopted to tackle these problems. Here, we have followed a strategy that combines the two; we have used ultra-thin Al2O3-y buffer layers incorporated between TiO2-x thin films taking into account both 3+/4+ oxidation states of Al/Ti cations. Our devices were tested by DC and pulsed voltage sweeping and in both cases demonstrated improved switching voltages. We believe that the Al2O3-y layers act as reservoirs of oxygen vacancies which are injected during EF, facilitate a filamentary switching mechanism and provide enhanced filament stability, as shown by the cycling endurance measurements.

  3. Nature of the fundamental band gap in GaNxP1-x alloys

    International Nuclear Information System (INIS)

    Shan, W.; Walukiewicz, W.; Yu, K. M.; Wu, J.; Ager, J. W. III; Haller, E. E.; Xin, H. P.; Tu, C. W.

    2000-01-01

    The optical properties of GaN x P 1-x alloys (0.007≤x≤0.031) grown by gas-source molecular-beam epitaxy have been studied. An absorption edge appears in GaN x P 1-x at energy below the indirect Γ V -X C transition in GaP, and the absorption edge shifts to lower energy with increasing N concentration. Strong photomodulation signals associated with the absorption edges in GaN x P 1-x indicate that a direct fundamental optical transition is taking place, revealing that the fundamental band gap has changed from indirect to direct. This N-induced transformation from indirect to direct band gap is explained in terms of an interaction between the highly localized nitrogen states and the extended states at the Γ conduction-band minimum. (c) 2000 American Institute of Physics

  4. Shielding properties of 80TeO2–5TiO2–(15−x) WO3–xAnOm glasses using WinXCom and MCNP5 code

    International Nuclear Information System (INIS)

    Dong, M.G.; El-Mallawany, R.; Sayyed, M.I.; Tekin, H.O.

    2017-01-01

    Gamma ray shielding properties of 80TeO 2 –5TiO 2 –(15−x) WO 3 –xA n O m glasses, where A n O m is Nb 2 O 5 = 0.01, 5, Nd 2 O 3 = 3, 5 and Er 2 O 3 = 5 mol% have been achieved. Shielding parameters; mass attenuation coefficients, half value layers, and macroscopic effective removal cross section for fast neutrons have been computed by using WinXCom program and MCNP5 Monte Carlo code. In addition, by using Geometric Progression method (G-P), exposure buildup factor values were also calculated. Variations of shielding parameters are discussed for the effect of REO addition into the glasses and photon energy. - Highlights: • The shielding properties of 80TeO 2 –5TiO 2 –(15−x) WO 3 –xA n O m glasses were evaluated. • WinXCom program and MCNP simulation codes were used in the calculations. • Good agreement was noticed between the WinXCom and MCNP5 code results.

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

    Science.gov (United States)

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

    2017-12-01

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

  6. 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

  7. Enhancement in dye-sensitized solar cells based on MgO-coated TiO2 electrodes by reactive DC magnetron sputtering

    International Nuclear Information System (INIS)

    Wu Sujuan; Han Hongwei; Tai Qidong; Zhang Jing; Xu Sheng; Zhou Conghua; Yang Ying; Hu Hao; Chen Bolei; Sebo, Bobby; Zhao Xingzhong

    2008-01-01

    A surface modification method was carried out by reactive DC magnetron sputtering to fabricate TiO 2 electrodes coated with insulating MgO for dye-sensitized solar cells. The MgO-coated TiO 2 electrode had been characterized by x-ray photoelectron spectroscopy (XPS), energy-dispersive x-ray spectroscopy (EDX), scanning electron microscopy (SEM), UV-vis spectrophotometer, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The study results revealed that the TiO 2 modification increases dye adsorption, decreases trap states and suppresses interfacial recombination. The effects of sputtering MgO for different times on the performance of DSSCs were investigated. It indicated that sputtering MgO for 3 min on TiO 2 increases all cell parameters, resulting in increasing efficiency from 6.45% to 7.57%

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

    Science.gov (United States)

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

    2018-03-01

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

  9. 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.

  10. 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.

  11. Density, thickness and composition measurements of TiO2 -SiO2 thin films by coupling X-ray reflectometry, ellipsometry and electron probe microanalysis-X

    International Nuclear Information System (INIS)

    Hodroj, A.; Roussel, H.; Crisci, A.; Robaut, F.; Gottlieb, U.; Deschanvres, J.L.

    2006-01-01

    Mixed TiO 2 -SiO 2 thin films were deposited by aerosol atmospheric CVD method by using di-acetoxi di-butoxi silane (DADBS) and Ti tetra-butoxide as precursors. By varying the deposition temperatures between 470 and 600 deg. C and the ratios between the Si and Ti precursors (Si/Ti) from 2 up to 16, films with different compositions and thicknesses were deposited. The coupled analysis of the results of different characterisation methods was used in order to determine the variation of the composition, the thickness and the density of the films. First EPMA measurements were performed at different acceleration voltages with a Cameca SX50 system. By analysing, with specific software, the evolution of the intensity ratio I x /I std versus the voltage, the composition and the mass thickness (product of density by the thickness) were determined. In order to measure independently the density, X-ray reflectometry experiments were performed. By analysing the value of the critical angle and the Kiessig fringes, the density and the thickness of the layers were determined. The refractive index and the thickness of the films were also measured by ellipsometry. By assuming a linear interpolation between the index value of the pure SiO 2 and TiO 2 films, the film composition was deduced from the refractive index value. XPS measurements were also performed in order to obtain an independent value of the composition. A good agreement between the ways to measure the density is obtained

  12. Transparent conductive electrodes of mixed TiO2−x–indium tin oxide for organic photovoltaics

    KAUST Repository

    Lee, Kyu-Sung

    2012-05-22

    A transparent conductive electrode of mixed titanium dioxide (TiO2−x)–indium tin oxide (ITO) with an overall reduction in the use of indium metal is demonstrated. When used in organic photovoltaicdevices based on bulk heterojunction photoactive layer of poly (3-hexylthiophene) and [6,6]-phenyl C61 butyric acid methyl ester, a power conversion efficiency of 3.67% was obtained, a value comparable to devices having sputtered ITO electrode. Surface roughness and optical efficiency are improved when using the mixed TiO2−x–ITO electrode. The consumption of less indium allows for lower fabrication cost of such mixed thin filmelectrode.

  13. Polyaniline nanowires on TiO2 nano/microfiber hierarchical nano/microstructures: Preparation and their photocatalytic properties

    International Nuclear Information System (INIS)

    Yu Qiaozhen; Wang Mang; Chen Hongzheng; Dai Zhengwei

    2011-01-01

    Highlights: → We fabricate PANI nanowire-on-TiO 2 nano/microfiber hierarchical nano/microstructure composite fiber films by electrospinning, calcinations and in situ polymerization. → PANI/TiO 2 composite fiber film exhibits high photocatalytic activity for the degradation of dye MB. → The photocatalytic activity and reusability of PANI/TiO 2 composite fiber film were lower than those of pure TiO 2 fiber film. - Abstract: TiO 2 /PANI composite fiber films were fabricated by electrospinning, calcinations and in situ polymerization. The morphology and structure of the resulting composites were analyzed by scanning electron micrograph, transmission electron micrograph, Fourier transform infrared spectroscopy and X-ray diffraction. It was found that this composite fiber film has a PANI nanowire-on-TiO 2 nano/microfiber hierarchical nano/microstructure. The surface morphology of this hierarchical nano/microstructure was related to the structure of TiO 2 nano/microfiber film, the time and temperature of in situ polymerization. Its photocatalytic property on methylene blue (MB) was studied, and the results showed that TiO 2 /PANI composite fiber film with this hierarchical nano/microstructure exhibited high photocatalytic activity for the degradation of MB under natural light. But both its photocatalytic activity and reusability were lower than those of pure TiO 2 fiber film. To improve the stability and reusability of TiO 2 /PANI composite fiber film, a direct chemical bonding of PANI chains onto TiO 2 surface, such as, the surface-initiated graft polymerization, is a useful method.

  14. Icariin-Loaded TiO2 Nanotubes for Regulation of the Bioactivity of Bone Marrow Cells

    Directory of Open Access Journals (Sweden)

    Yanli Zhang

    2018-01-01

    Full Text Available To explore the effects of icariin on the biocompatibility of dental implants, icariin- (ICA- loaded TiO2 nanotubes were fabricated on Ti substrates via anodic oxidation and physical absorption. The surface characteristics of the specimens were monitored by field emission scanning electron microscopy (FE-SEM, X-ray diffractometry (XRD, contact angle measurements (CA, and high-pressure liquid chromatography. Additionally, the activities of bone marrow cells, such as cytoskeletal, proliferative activities, mineralization, and osteogenesis-related gene expression on the substrates were investigated in detail. The characterization results demonstrated that ICA-loaded TiO2 nanotubes were successfully fabricated and the hydrophilicity of these TiO2 nanotubes was significantly higher than that of the pure Ti groups. The results also showed that ICA-loaded TiO2 nanotubes might not have enhanced effects on cell proliferation and ALP expression. However, it seemed to significantly promote differentiation of bone marrow cells, demonstrated by enhancing the formation of mineralized nodule and the upregulation of the gene expression such as OC, BSP, OPN, and COL-1. The results indicated that ICA-loaded TiO2 nanotubes can modulate bioactivity of bone marrow cells, which is promising for potential applications in the orthopedics field.

  15. Study of the phase composition of Fe2O3 and Fe2O3/TiO2 nanoparticles using X-ray diffraction and Debye formula

    Czech Academy of Sciences Publication Activity Database

    Valeš, V.; Poltierová Vejpravová, J.; Holý, V.; Tyrpekl, Václav; Brázda, P.; Doyle, S.

    2010-01-01

    Roč. 7, č. 5 (2010), s. 1399-1404 ISSN 1862-6351 Institutional research plan: CEZ:AV0Z40320502 Keywords : Fe2O3/TiO2 * nanocomposites * structure * phase transition * annealing Subject RIV: CA - Inorganic Chemistry

  16. Strong composition-dependent disorder in InAs1-xNx alloys

    International Nuclear Information System (INIS)

    Benaissa, H.; Zaoui, A.; Ferhat, M.

    2009-01-01

    We investigate the main causes of disorder in the InAs 1-x N x alloys (x = 0, 0.03125, 0.0625, 0.09375, 0.125, 0.25, 0.5, 0.75, 0.875, 0.90625, 0.9375, 0.96875 and 1). The calculation is based on the density-functional theory in the local-density approximation. We use a plane wave-expansion non-norm conserving ab initio Vanderbilt pseudopotentials. To avoid the difficulty of considering the huge number of atomic configurations, we use an appropriate strategy in which we consider four configurations for a given composition where the N atoms are not randomly distributed. We mainly show that the band gap decreases (increases) rapidly with increasing (decreasing) compositions of N. As a consequence the optical band gap bowing is found to be strong and composition dependent. The obtained compounds, from these alloys, may change from semi-conducting to metal (passing to a negative bowing) and could be useful for device applications, especially at certain composition.

  17. Facile fabrication of epoxy-TiO2 nanocomposites: A critical analysis of TiO2 impact on mechanical properties and toughening mechanisms.

    Science.gov (United States)

    Goyat, M S; Rana, S; Halder, Sudipta; Ghosh, P K

    2018-01-01

    Optimized ultrasonic assisted dispersion of un-functionalized titanium dioxide (TiO 2 ) nanoparticles (0.5-20wt%) into epoxy resin is reported. The investigation shows that there is a direct relation among nanoparticles content, inter-particle spacing and cluster size of the particles on the glass transition temperature (T g ) and tensile properties of the prepared nanocomposites. A significant improvement in tensile strength and modulus with minimal detrimental effect on the toughness was observed for the prepared composites, where compared to pristine epoxy resins, about 26% and 18% improvement in tensile strength and strain-to-break %, respectively, was observed for 10wt% particles loading, whereas a maximum improvement of about 54% for tensile toughness was observed for 5wt% particles loaded resins. The investigations found that a strong particle-matrix interface results in the enhancement of the mechanical properties due to leading toughening mechanisms such as crack deflection, particle pull out and plastic deformation. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. DSC, Raman and impedance spectroscopy studies on the xB2O3 - (90 - x)TeO2 - 10TiO2 (where x = 0 to 50 mol%) glass system

    Science.gov (United States)

    Sripada, Suresh; Rani, D. Esther Kalpana; Upender, G.; Pavani, P. Gayathri

    2013-03-01

    Titanium boro tellurite glasses in the xB2O3 -(90- x) TeO2 - 10TiO2 (where x = 0 to 50 mol%) system were prepared by using the conventional melt-quenching technique. Glass transition temperatures were measured with differential scanning calorimetry (DSC) and found to be in the range of 300-370 °C. The Raman spectra showed a cleavage of the continuous TeO4 (tbp) network by breaking of the Te-O-Te linkages. The relative transition of TeO4 - groups to TeO3 - groups is accompanied by a change in the oxygen coordination of the boron from 3 to 4 (BO3 - to BO4 -). The impedance plots Z″( ω) versus Z'( ω) for all the glass samples were recorded and found to exhibit a single circle. The AC conductivity of all glass samples was studied in the frequency range from 100 Hz to 1 MHz and in the temperature range from room temperature (RT) to 375 °C. The AC conductivity decreased by about one order in magnitude with increasing B2O3 content. The conductivity was found to be on the order of 10-4.5 to 10-6 (Ωcm)-1 at 375 °C and 1 MHz for 10 mol% and 50 mol% B2O3 contents, respectively. The relaxation behavior in these glass samples is discussed based on the complex modulus and impedance data.

  19. Progress in measurement of (n,x) cross sections at HST in 1995

    Energy Technology Data Exchange (ETDEWEB)

    Bangjiao, Ye; Zhongmin, Wang; Yangmei, Fan; Rongdian, Han; Xiaoqi, Yu; Huaijiang, Du [Department of Modern Physics, Univ. of Sci. and Tech. of China (China)

    1996-06-01

    The measurement of energy spectrum and angular distributions of protons emission from reaction induced by 14.6 MeV neutron bombarding stainless steel has been performed at Univ. of Sci. and Tech. of China, Hefei (HST) by using multitelescope system. 14.6 MeV neutrons were produced by 150 KeV Cockcroft-Walton accelerator. The 1Cr18Ni9Ti (type 321) stainless steel target with 0.8 mm thick and 40 mm height was used. The progress on measurement of {sup nat}Ni(n,x{alpha}) reaction cross sections are introduced. (2 figs.).

  20. Shielding properties of 80TeO2-5TiO2-(15-x) WO3-xAnOm glasses using WinXCom and MCNP5 code

    Science.gov (United States)

    Dong, M. G.; El-Mallawany, R.; Sayyed, M. I.; Tekin, H. O.

    2017-12-01

    Gamma ray shielding properties of 80TeO2-5TiO2-(15-x) WO3-xAnOm glasses, where AnOm is Nb2O5 = 0.01, 5, Nd2O3 = 3, 5 and Er2O3 = 5 mol% have been achieved. Shielding parameters; mass attenuation coefficients, half value layers, and macroscopic effective removal cross section for fast neutrons have been computed by using WinXCom program and MCNP5 Monte Carlo code. In addition, by using Geometric Progression method (G-P), exposure buildup factor values were also calculated. Variations of shielding parameters are discussed for the effect of REO addition into the glasses and photon energy.

  1. 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.

  2. Synthesis and characterization of Fe3+ doped TiO2 nanoparticles and films and their performance for photocurrent response under UV illumination

    International Nuclear Information System (INIS)

    Elghniji, Kais; Atyaoui, Atef; Livraghi, Stefano; Bousselmi, Latifa; Giamello, Elio; Ksibi, Mohamed

    2012-01-01

    Graphical abstract: Schematic diagram illustrating the charge transfer from excited TiO 2 to the different states of Fe 3+ ions; C B and V B refer to the energy levels of the conduction and valence bands of TiO 2 , respectively. Highlights: ► In this study we examine the Iron as catalyst precursor to synthesize the Fe 3+ doped TiO 2 nanoparticles. ► The Fe 3+ doped TiO 2 catalysts show the presence of a mixed phase of anatase. ► The iron is completely absent in the XRD pattern of the doped iron TiO 2 powder. ► The analysis of EPR result further confirms that Fe 3+ ion are successfully doped in the TiO 2 lattice by substituting Ti 4+ . ► Fe 3+ doping can efficiently separate the photo-generated electrons and holes. - Abstract: Undoped TiO 2 and Fe 3+ doped (0.1, 0.3, 0.6 and 1 wt.%) TiO 2 nanoparticles have been synthesized by the acid-catalyzed sol–gel method. Iron cations are introduced in the initial solution, before gelification, what promotes their lattice localization. The Fe 3+ doped TiO 2 films have been fabricated using a dip-coating technique. The effect of iron content on the crystalline structure, phase transformation and grain growth were determined by X-ray diffraction (XRD), Raman spectroscopy, UV–visible diffused reflectance spectroscopy (DRS) and Electron paramagnetic resonance (EPR) spectroscopy. It has demonstrated that all catalysts are composed of mixed-phase crystals of anatase and brookite with anatase as dominant phase. The crystallinity of the brookite and anatase phases decreased with increasing the iron content. The analysis of EPR result further confirms that Fe 3+ ion are successfully doped in the TiO 2 lattice by substituting Ti 4+ . It was demonstrated that Fe 3+ ion in the TiO 2 films plays a role as the intermediate for the efficient separation of photogenerated hole–electron pairs and increases the photocurrent response of the film under UV light irradiation. The maximum photocurrent is obtained on the Fe 3+ doped Ti

  3. Hydrothermal synthesis of TiO2-ZnO-graphene nanocomposite towards photocatalytic and photovoltaic applications

    International Nuclear Information System (INIS)

    Gayathri, S.; Jayabal, P.; Ramakrishnan, V.

    2015-01-01

    Titanium dioxide (TiO 2 ) - Zinc oxide (ZnO) - Graphene (G) nanocomposite was successfully synthesized through facile hydrothermal method. The X-ray diffraction (XRD) pattern and the micro-Raman spectroscopic technique revealed the formation of TiO 2 -ZnO-Graphene (TZG) nanocomposite. The ZnO and TiO 2 nanoparticles decorated graphene sheets were clearly noticeable in the Field Emission Scanning Electron Micrograph (FE-SEM). The UV-Visible absorption spectra clearly indicated that the formation of TZG nanocomposite enriched the absorption in the visible region. Hence, the prepared nanocomposite can be used as photocatalyst to remove organic dyes from water and as photoanode in the fabrication of dye sensitized solar cells (DSSCs)

  4. Hydrothermal synthesis of TiO2-ZnO-graphene nanocomposite towards photocatalytic and photovoltaic applications

    Science.gov (United States)

    Gayathri, S.; Jayabal, P.; Ramakrishnan, V.

    2015-06-01

    Titanium dioxide (TiO2) - Zinc oxide (ZnO) - Graphene (G) nanocomposite was successfully synthesized through facile hydrothermal method. The X-ray diffraction (XRD) pattern and the micro-Raman spectroscopic technique revealed the formation of TiO2-ZnO-Graphene (TZG) nanocomposite. The ZnO and TiO2 nanoparticles decorated graphene sheets were clearly noticeable in the Field Emission Scanning Electron Micrograph (FE-SEM). The UV-Visible absorption spectra clearly indicated that the formation of TZG nanocomposite enriched the absorption in the visible region. Hence, the prepared nanocomposite can be used as photocatalyst to remove organic dyes from water and as photoanode in the fabrication of dye sensitized solar cells (DSSCs).

  5. Photoelectrolchemical performance of PbS/CdS quantum dots co-sensitized TiO2 nanosheets array film photoelectrodes

    International Nuclear Information System (INIS)

    Yao, Huizhen; Li, Xue; Liu, Li; Niu, Jiasheng; Ding, Dong; Mu, Yannan; Su, Pengyu; Wang, Guangxia; Fu, Wuyou; Yang, Haibin

    2015-01-01

    Herein, PbS/CdS quantum dots (QDs) co-sensitized titanium dioxide nanosheets array (TiO 2 NSs) films were reported for the first time. The TiO 2 NSs films exposed {001} facets were vertically grown on transparent conductive fluorine-doped tin oxide (FTO) glass substrates by a facile hydrothermal method. The PbS/CdS QDs were assembled on TiO 2 NSs photoelectrode by successive ionic layer adsorption and reaction (SILAR). The X-ray diffraction pattern (XRD) and transmission electron microscopy (TEM) verified that QDs with a diameter less than 20 nm were uniformly anchored on the surface of the TiO 2 NSs films. The QDs co-sensitization can significantly extend the absorption range and increase the absorption property of the photoelectrode by UV–vis absorption spectra. The optimal photoelectrolchemical (PEC) performance of PbS/CdS QDs co-sensitization TiO 2 NSs was with photocurrent density of 6.12 mA cm −2 under an illumination of AM 1.5 G, indicating the TiO 2 NSs films co-sensitized by PbS/CdS QDs have potential applications in solar cells. - Highlights: • TiO 2 nanosheets films were fabricated by a simple hydrothermal. • TiO 2 nanosheets film exposed high energy facets was with gaps. • PbS/CdS co-sensitized TiO 2 nanosheets film was obtained for the first time. • Photocurrent intensity of the novel photoelectrode increased to 6.12 mA cm −2

  6. Synthesis of two-dimensional nanowall of Cu-Doped TiO2 and its application as photoanode in DSSCs

    Science.gov (United States)

    Dahlan, Dahyunir; Md Saad, Siti Khatijah; Berli, Ade Usra; Bajili, Abdil; Umar, Akrajas Ali

    2017-07-01

    Two-dimensional nanowall of Cu-doped TiO2 (CuTNW) has been prepared in this work to study the role of Cu doping on its photoactivity properties and its photovoltaic performance as photoanode in a dye-sensitized solar cell (DSSC). TiO2 nanowall with five Cu ion doping, i.e. 6.25, 12.5, 25.0, 50.0 and 100.0 mM, were prepared via a liquid-phase deposition method using ammoniumhexafluorotitanate and hexamethylenetetramine as the reagents with a growth temperature of 90 °C. The X-Ray Diffraction (XRD), X-ray energy dispersion (EDX) and diffuse optical reflectance spectroscopy analysis results confirmed the successfulness of the Cu doping process in the TiO2 nanowall and effective modification on the photoactivity of the TiO2 nanowall. We found that the power conversion efficiency of the DSSC utilizing TiO2 nanowall as photoanode can be enhanced up to 2 times, i.e. from 0.2% to 0.44%, when the TiO2 nanowall doped with Cu ion. The nanostructure preparation, device fabrication and the mechanism for the device performance enhancement will be discussed.

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

    Science.gov (United States)

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

    2016-06-29

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

  8. Instability of Hydrogenated TiO2

    Energy Technology Data Exchange (ETDEWEB)

    Nandasiri, Manjula I.; Shutthanandan, V.; Manandhar, Sandeep; Schwarz, Ashleigh M.; Oxenford, Lucas S.; Kennedy, John V.; Thevuthasan, Suntharampillai; Henderson, Michael A.

    2015-11-06

    Hydrogenated TiO2 (H-TiO2) is toted as a viable visible light photocatalyst. We report a systematic study on the thermal stability of H-implanted TiO2 using X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA). Protons (40 keV) implanted at a ~2 atom % level within a ~120 nm wide profile of rutile TiO2(110) were situated ~300 nm below the surface. NRA revealed that this H-profile broadened preferentially toward the surface after annealing at 373 K, dissipated out of the crystal into vacuum at 473 K, and was absent within the beam sampling depth (~800 nm) at 523 K. Photoemission showed that the surface was reduced in concert with these changes. Similar anneals had no effect on pristine TiO2(110). The facile bulk diffusivity of H in rutile, as well as its activity toward interfacial reduction, significantly limits the utilization of H-TiO2 as a photocatalyst. This work was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle. The research was performed using the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory.

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  10. Hollow TiO2 modified reduced graphene oxide microspheres encapsulating hemoglobin for a mediator-free biosensor.

    Science.gov (United States)

    Liu, Hui; Guo, Kai; Duan, Congyue; Dong, Xiaonan; Gao, Jiaojiao

    2017-01-15

    Hollow TiO 2 modified reduced graphene oxide microspheres (hollow TiO 2 -rGO microspheres or H-TiO 2 -rGO MS) have been synthesized and then be used to immobilize hemoglobin (Hb) to fabricate a mediator-free biosensor. The morphology and structure of hollow TiO 2 -rGO microspheres were characterized by scanning electron microscopy, transmission electronic microscopy and X-ray diffraction. Results of spectroscopy and electrochemistry tests revealed that hollow TiO 2 -rGO microsphere is an excellent immobilization matrix with biocompatibility for redox protein, affording good protein bioactivity and stability. The hollow TiO 2 -rGO microspheres with special structure and component enhance the immobilization efficiency of proteins and facilitate the direct electron transfer, which result in the better H 2 O 2 detection performance-the wide linear range of 0.1-360μM for H 2 O 2 (sensitivity of 417.6 μA mM -1 cm -2 ) and the extremely low detection limit of 10nM for H 2 O 2 . Moreover, the hollow microsphere can provide a protective microenvironment for Hb to make the as-prepared biosensor improve long-term stability. The as-prepared biosensor retains 95.4% of the initial response to H 2 O 2 after 60-d storage. Hence, this work suggests that if can be fabricated a mediator-free biosensor, hollow TiO 2 -rGO microspheres will find wide potential applications in environmental analysis and biomedical detection. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Uniformly distributed anatase TiO2 nanoparticles on graphene: Synthesis, characterization, and photocatalytic application

    International Nuclear Information System (INIS)

    Bai, Xue; Zhang, Xiaoyuan; Hua, Zulin; Ma, Wenqiang; Dai, Zhangyan; Huang, Xin; Gu, Haixin

    2014-01-01

    Highlights: • Uniform distributed TiO 2 nanoparticles on graphene by a modified method. • Reduced recombination rate of photogenerated electron–hole pairs. • Effective charge transfer from TiO 2 to graphene. • Better photocatalytic activity upon UV and visible irradiation. • A mechanism of bisphenol A degradation process is proposed. - Abstract: Graphene (GR)/TiO 2 nanocomposites are successfully synthesized using a simple and efficient hydrothermal method. Even-sized anatase TiO 2 nanoparticles are uniformly distributed on GR. The GR/TiO 2 nanocomposites exhibit an extended light absorption range and decreased electron–hole recombination rates. The photocatalytic activity of the as-prepared GR/TiO 2 nanocomposites for bisphenol A (BPA) degradation is investigated under UV (λ = 365 nm) and visible (λ ⩾ 400 nm) light irradiation. The results show that GR/TiO 2 nanocomposites have significantly higher photocatalytic activity than P25 (pure TiO 2 ). The large increase in photocatalytic activity is mostly attributed to effective charge transfer from TiO 2 nanoparticles to GR, which suppresses charge recombination during the photocatalytic process. After five successive cycles, the photodegradation activity of the GR/TiO 2 nanocomposites shows no significant decrease, which indicates that the nanocomposites are stable under UV and visible light. X-ray photoelectron spectroscopy (XPS) is used to investigate the chemical bonds of GR/TiO 2 nanocomposites before and after degradation to determine the degradation intermediate products of BPA under irradiation. A proposed degradation reaction pathway of BPA is also established. This study provides new insights into the fabrication and practical application of high-performance photocatalysts in wastewater treatment

  12. 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.

  13. Hierarchical architectures TiO2: Pollen-inducted synthesis, remarkable crystalline-phase stability, tunable size, and reused photo-catalysis

    International Nuclear Information System (INIS)

    Dou, Lingling; Gao, Lishuang; Yang, Xiaohui; Song, Xiuqin

    2012-01-01

    Highlights: ► The synthetic method is much milder and simpler than that of conventional methods. ► The obtained hierarchical TiO 2 shows three interesting hierarchical morphology. ► The products have tunable crystal phase structures. ► The pure phase of anatase can be retained after being annealed at 900 °C. ► The product exhibits higher and reused photo-catalytic activity. - Abstract: TiO 2 with hierarchical architectures, tunable crystalline phase and thermal stability is successfully fabricated on a large scale through a facile hydrolysis process of TiCl 4 combining with inducing of pollen. The structure of the as-prepared TiO 2 is characterized by X-ray diffraction, Raman spectroscopy, infrared spectra, and scanning electron microscopy. The experimental results indicate that different phases (anatase, rutile or mixed crystallite) of TiO 2 can be synthesized by controlling the experimental conditions. The pure phase of rutile or anatase can be obtained at 100 °C, while the pure phase of anatase can be retained after being annealed at 900 °C. The hierarchical structures TiO 2 are constitute through self-assembly of nanoparticles or nanorods TiO 2 , which exhibit high and reused photo-catalytic properties for degradation of methylene blue.

  14. 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.

  15. Photocatalytic effects for the TiO2-coated phosphor materials

    International Nuclear Information System (INIS)

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

    2011-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Bessais B.

    2012-06-01

    Full Text Available One of the most promising ideas to enhance the photocatalytic efficiency of the TiO2 is to couple this photocatalyst with other semiconductors. In this work, we report on the development of photo-catalytic properties of two types of composites based on TiO2 – ITO (Indium Tin Oxide and TiO2 – ZnO deposited on conventional ceramic substrates. The samples were characterized by X-ray diffraction (XRD and transmission Electron Microscopy (TEM. The photo-catalytic test was carried out under UV light in order to reduce/oxidize a typical textile dye (Cibacron Yellow. The experiment was carried out in a bench scale reactor using a solution having a known initial dye concentration. After optimization, we found that both nanocomposites exhibit better photocatalytic activity compared to the standard photocatalyst P25 TiO2.

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

    International Nuclear Information System (INIS)

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

    2006-01-01

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

  18. Conductometric sensor for ammonia and ethanol using gold nanoparticle-doped mesoporous TiO2

    International Nuclear Information System (INIS)

    Xiong, Wei; Liu, Huanhuan; Liu, Shantang

    2015-01-01

    We describe uniform and high-temperature-stable mesoporous TiO 2 beads functionalized with gold nanoparticles (AuNPs-TiO 2 ) for use in conductometric sensing of gases and organic vapors. The size of the interconnected main mesopores of the TiO 2 beads ranges from 8 to 15 nm, and the AuNPs have diameters between 8 and 10 nm. The mesoporous TiO 2 beads are formed during calcination while the structure-directing template agent is removed. Monodispersed AuNPs are formed by reduction in-situ and are placed inside the mesoporous TiO 2 framework. This prevents aggregation of the AuNPs even at 500 °C. The materials were characterized by UV–vis spectroscopy, scanning and transmission electron microscopy, nitrogen adsorption-desorption, and X-ray diffraction. Comb-type gold electrodes were then fabricated on an alumina substrate and are shown to display excellent properties in terms of sensing ammonia, ethanol, methanol or acetone. The sensitivity (defined as the ratio of resistivities under vapor and air) of a typical AuNPs(0.5 %)-TiO 2 gas sensor for ethanol reached up to 5.65 at above 600 ppm at 75 °C. Response time and recovery times (t 90  ≤ 20 s) are faster than (or comparable to) other metal-doped TiO 2 sensors, and working temperatures are much lower. An interesting observation was made in that the changes in the conductivity of the sensor change with temperature. The sensor prepared with AuNPs(0.5 %)-TiO 2 is of the p-type (in its response to ammonia gas) at 45 °C, but becomes n-type at 20 °C. Obviously, rather slight changes in temperature lead to a complete change in the direction of the conductometric signal change. This may provide a new aspect in terms of selective and highly sensitive detection of ammonia at ambient and slightly elevated temperatures. (author)

  19. Sustained release of melatonin from TiO2 nanotubes for modulating osteogenic differentiation of mesenchymal stem cells in vitro.

    Science.gov (United States)

    Lai, Min; Jin, Ziyang; Tang, Qiang; Lu, Min

    2017-10-01

    To control the sustained release of melatonin and modulate the osteogenic differentiation of mesenchymal stem cells (MSCs), melatonin was firstly loaded onto TiO 2 nanotubes by direct dropping method, and then a multilayered film was coated by a spin-assisted layer-by-layer technique, which was composed of chitosan (Chi) and gelatin (Gel). Successful fabrication was characterized by field emission scanning electron microscopy, atomic force microscope, X-ray photoelectron spectroscopy and contact angle measurement, respectively. The efficient sustained release of melatonin was measured by UV-visible-spectrophotometer. After 2 days of culture, well-spread morphology was observed in MSCs grown on the Chi/Gel multilayer-coated melatonin-loaded TiO 2 nanotube substrates as compared to different groups. After 4, 7, 14 and 21 days of culture, the multilayered-coated melatonin-loaded TiO 2 nanotube substrates increased cell proliferation, increased alkaline phosphatase (ALP) and mineralization, increased expression of mRNA levels for runt-related transcription factor 2 (Runx2), ALP, osteopontin (OPN) and osteocalcin (OC), indicative of osteoblastic differentiation. These results demonstrated that Chi/Gel multilayer-coated melatonin-loaded TiO 2 nanotube substrates promoted cell adhesion, spreading, proliferation and differentiation and could provide an alternative fabrication method for titanium-based implants to enhance the osteointegration between bone tissues and implant surfaces.

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

    Institute of Scientific and Technical Information of China (English)

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

    2017-01-01

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

  1. Biocorrosion of TiO2 nanoparticle coating of Ti–6Al–4V in DMEM under specific in vitro conditions

    International Nuclear Information System (INIS)

    Höhn, Sarah; Virtanen, Sannakaisa

    2015-01-01

    Highlights: • Possibility to fabricate a TiO 2 NP-coating on Ti–6Al–4V by a simple spin-coating method. • The NP-coating enhances biomimetic apatite formation on the surface immersed in DMEM. • The TiO 2 coating can efficiently reduce Al release from the alloy during immersion in DMEM. • TiO 2 NP-coating makes the surface more bioactive. - Abstract: A TiO 2 nanoparticle coating was prepared on a biomedical Ti–6Al–4V alloy using “spin-coating” technique with a colloidal suspension of TiO 2 nanopowders with the aim to optimize the surface morphology (e.g., roughness) for improved biocompatibility. The influence of a TiO 2 nanoparticle (NP) coating on the corrosion behavior, metal ion release, and biomimetic apatite formation was studied in DMEM, at 37.5 °C with a continuous supply of 5% CO 2 . Electrochemical impedance spectroscopy measurements indicate a formation of a new layer on the surface of the NP-coated sample upon 28 days immersion in DMEM. Scanning electron microscopy (SEM) and X-ray spectroscopy confirm that the surface of the NP-coated Ti–6Al–4V shows a complete coverage by a Ca–phosphate layer in contrast to the non-coated Ti–6Al–4V alloy. Hence, the TiO 2 -NP coating strongly enhances biomimetic apatite formation on the alloy surface. In addition, the TiO 2 -NP coating can efficiently reduce Al-release from the alloy, for which the bare Ti–6Al–4V alloy is significant for at least 28 days of immersion in DMEM

  2. 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.

  3. High pressure synthesis of amorphous TiO2 nanotubes

    Directory of Open Access Journals (Sweden)

    Quanjun Li

    2015-09-01

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

  4. Analysis of Polymorphic Nanocrystals of TiO2 by X-Ray Rietveld Refinement and High-Resolution Transmission Electron Microscopy: Acetaldehyde Decomposition

    Directory of Open Access Journals (Sweden)

    R. Carrera

    2008-01-01

    Full Text Available In this work, TiO2 nanocrystals were synthesized by the sol-gel method. These materials were annealed at 200 and 500∘C; and characterized by the XRD-Rietveld refinement; and by BET and TEM. As for the low-temperature-treated sample (200∘C, nanocrystals with small crystallite sizes (7 nm and high abundance of anatase, coexisting with the brookite phase, were obtained. Meanwhile, the sample annealed at 500∘C showed an increased crystallite size (22 nm and an important polymorphic increment. The sample annealed at 200∘C showed a high activity in the photocatalytic decomposition of acetaldehyde.

  5. 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

  6. Growth and characterization of hydroxyapatite nanorice on TiO2 nanofibers

    KAUST Repository

    Chetibi, Loubna

    2014-04-01

    Hydroxyapatite (HA) coating with nanoparticles like nanorice is fabricated on chemically pretreated titanium (Ti) surface, through an electrochemical deposition approach, for biomaterial applications. The Ti surface was chemically patterned with anatase TiO2 nanofibers. These nanofibers were prepared by in situ oxidation of Ti foils in a concentrated solution of H 2O2 and NaOH, followed by proton exchange and calcinations. Afterward, TiO2 nanofibers on Ti substrate were coated with HA nanoparticles like nanorice. The obtained samples were annealed at high temperature to produce inter diffusion between TiO2 and HA layers. The resultant layers were characterized by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction (XRD), Infrared Spectroscopy (FTIR), corrosion tests in SBF solution, and Electron Probe Micro Analysis (EPMA). It was found that only Ti from the titanium substrate diffuses into the HA coating and a good corrosion resistance in simulated body fluid was obtained. © 2014 Elsevier B.V. All rights reserved.

  7. Dye-sensitized solar cells based on Cr-doped TiO2 nanotube photoanodes

    Institute of Scientific and Technical Information of China (English)

    M.M.Momeni

    2017-01-01

    The effect of chromium doping on the photovoltaic efficiency of dye-sensitized solar cells (DSSCs) with anodized TiO2 nanotubes followed by an annealing process was investigated.Cr-doped TiO2 nanotubes (CrTNs) with different amounts of chromium were obtained by anodizing of titanium foils in a single-step process using potassium chromate as the chromium source.Film features were investigated by scanning electron microscopy (SEM),X-ray diffraction (XRD),energy-dispersive X-ray spectroscopy (EDX),and ultraviolet-visible (UV-Vis) spectroscopy.It is clearly seen that highly ordered TiO2 nanotubes are formed in an anodizing solution free of potassium chromate,and with a gradual increase in the potassium chromate concentration,these nanotube structures change to nanoporous and compact films without porosity.The photovoltaic efficiencies of fabricated DSSCs were characterized by a solar cell measurement system via the photocurrent-voltage (Ⅰ-Ⅴ) curves.It is found that the photovoltaic efficiency of DSSCs with CrTNsl sample is improved by more than three times compared to that of DSSCs with undoped TNs.The energy conversion efficiency increases from 1.05 % to 3.89 % by doping of chromium.

  8. Development of Dye-Sensitized Solar Cells with Sputtered N-Doped TiO2 Thin Films: From Modeling the Growth Mechanism of the Films to Fabrication of the Solar Cells

    OpenAIRE

    Duarte, D. A.; Massi, M.; da Silva Sobrinho, A. S.

    2014-01-01

    In this paper, nitrogen-doped TiO2 thin films were deposited by DC reactive sputtering at different doping levels for the development of dye-sensitized solar cells. The mechanism of film growth during the sputtering process and the effect of the nitrogen doping on the structural, optical, morphological, chemical, and electronic properties of the TiO2 were investigated by numerical modeling and experimental methods. The influence of the nitrogen doping on the working principle of the prototype...

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

    Science.gov (United States)

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

    2011-02-01

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

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

    Directory of Open Access Journals (Sweden)

    Fenglin Huang

    2012-12-01

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

  11. An Alternative to Annealing TiO2 Nanotubes for Morphology Preservation: Atmospheric Pressure Plasma Jet Treatment.

    Science.gov (United States)

    Seo, Sang-Hee; Uhm, Soo-Hyuk; Kwon, Jae-Sung; Choi, Eun Ha; Kim, Kwang-Mahn; Kim, Kyoung-Nam

    2015-03-01

    Titanium oxide nanotube layer formed by plasma electrolytic oxidation (PEO) is known to be excellent in biomaterial applications. However, the annealing process which is commonly performed on the TiO2 nanotubes cause defects in the nanotubular structure. The purpose of this work was to apply a non-thermal atmospheric pressure plasma jet on diameter-controlled TiO2 nanotubes to mimic the effects of annealing while maintaining the tubular structure for use as biomaterial. Diameter-controlled nanotube samples fabricated by plasma electrolytic oxidation were dried and prepared under three different conditions: untreated, annealed at 450 °C for 1 h in air with a heating rate of 10 °C/min, and treated with an air-based non-thermal atmospheric pressure plasma jet for 5 minutes. The contact angle measurement was investigated to confirm the enhanced hydrophilicity of the TiO2 nanotubes. The chemical composition of the surface was studied using X-ray photoelectron spectroscopy, and the morphology of TiO2 nanotubes was examined by field emission scanning electron microscopy. For the viability of the cell, the attachment of the osteoblastic cell line MC3T3-E1 was determined using the water-soluble tetrazolium salt assay. We found that there are no morphological changes in the TiO2 nanotubular structure after the plasma treatment. Also, we investigated a change in the chemical composition and enhanced hydrophilicity which result in improved cell behavior. The results of this study indicated that the non-thermal atmospheric pressure plasma jet results in osteoblast functionality that is comparable to annealed samples while maintaining the tubular structure of the TiO2 nanotubes. Therefore, this study concluded that the use of a non-thermal atmospheric pressure plasma jet on nanotube surfaces may replace the annealing process following plasma electrolytic oxidation.

  12. Performance of Erbium-doped TiO2 thin film grown by physical vapor deposition technique

    Science.gov (United States)

    Lahiri, Rini; Ghosh, Anupam; Dwivedi, Shyam Murli Manohar Dhar; Chakrabartty, Shubhro; Chinnamuthu, P.; Mondal, Aniruddha

    2017-09-01

    Undoped and Erbium-doped TiO2 thin films (Er:TiO2 TFs) were fabricated on the n-type Si substrate using physical vapour deposition technique. Field emission scanning electron microscope showed the morphological change in the structure of Er:TiO2 TF as compared to undoped sample. Energy dispersive X-ray spectroscopy (EDX) confirmed the Er doping in the TiO2 thin film (TF). The XRD and Raman spectrum showed the presence of anatase phase TiO2 and Er2O3 in the Er:TiO2 TF. The Raman scattering depicted additional number of vibrational modes for Er:TiO2 TF due to the presence of Er as compared to the undoped TiO2 TF. The UV-Vis absorption measurement showed that Er:TiO2 TF had approximately 1.2 times more absorption over the undoped TiO2 TF in the range of 300-400 nm. The main band transition, i.e., the transition between the oxygen (2p) state and the Ti (3d) state was obtained at 3.0 eV for undoped TiO2 and at 3.2 eV for Er:TiO2 TF, respectively. The photo responsivity measurement was done on both the detectors, where Er:TiO2 TF detector showed better detectivity ( D *), noise equivalent power and temporal response as compared to undoped detector under ultra-violet illumination.

  13. Photoelectrochemical Performances and Potential Applications of TiO2 Nanotube Arrays Modified with Ag and Pt Nanoparticles

    International Nuclear Information System (INIS)

    Xu, Guangqing; Liu, Haipeng; Wang, Jinwen; Lv, Jun; Zheng, Zhixiang; Wu, Yucheng

    2014-01-01

    TiO 2 nanotube arrays (NTAs) modified with Ag (Ag/TiO 2 ) and Pt (Pt/TiO 2 ) nanoparticles were fabricated by anodic oxidation combined with photoreduction and hydrothermal methods, respectively. Structures, element components and morphologies of TiO 2 , Ag/TiO 2 and Pt/TiO 2 NTAs were measured by X-ray diffraction diffractometer, X-ray photoelectron spectroscopy, scanning electron microscope and transmission electron microscope. The photoeletrochemical performances of TiO 2 , Pt/TiO 2 and Ag/TiO 2 NTAs were characterized by cyclic voltammetry and amperometry in phosphate buffer solution in absence and presence of glucose. Modifications of Ag and Pt nanoparticles play different roles in the photoelectrochemical process and have different potential applications. Ag nanoparticles decrease the photocurrent in buffer solution but increase the photocurrent response to organic compounds, which is fit for electrochemical detection of organic compounds due to the low background photocurrent and high photocurrent response. Ag/TiO 2 NTAs achieve the best detection performance with sensitivity of 0.152 μA/μM and detection limit of 0.53 μM. On the contrary, Pt nanoparticles can enhance the photocurrent of TiO 2 NTAs in buffer solution but decrease the photocurrent response to organic compounds, which are benefit for photocatalytic water splitting but not for photoelectrochemical detection

  14. 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)

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

    International Nuclear Information System (INIS)

    Trung, Tran; Ha, Chang-Sik

    2004-01-01

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

  16. Efficient planar n-i-p type heterojunction flexible perovskite solar cells with sputtered TiO2 electron transporting layers.

    Science.gov (United States)

    Mali, Sawanta S; Hong, Chang Kook; Inamdar, A I; Im, Hyunsik; Shim, Sang Eun

    2017-03-02

    The development of hybrid organo-lead trihalide perovskite solar cells (PSCs) comprising an electron transporting layer (ETL), a perovskite light absorber and a hole transporting layer (HTL) has received significant attention for their potential in efficient PSCs. However, the preparation of a compact and uniform ETL and the formation of a uniform light absorber layer suffer from a high temperature processing treatment and the formation of unwanted perovskite islands, respectively. A low temperature/room temperature processed ETL is one of the best options for the fabrication of flexible PSCs. In the present work, we report the implementation of a room temperature processed compact TiO 2 ETL and the synthesis of extremely uniform flexible planar PSCs based on methylammonium lead mixed halides MAPb(I 1-x Br x ) 3 (x = 0.1) via RF-magnetron sputtering and a toluene dripping treatment, respectively. The compact TiO 2 ETLs with different thicknesses (30 to 100 nm) were directly deposited on a flexible PET coated ITO substrate by varying the RF-sputtering time and used for the fabrication of flexible PSCs. The photovoltaic properties revealed that flexible PSC performance is strongly dependent on the TiO 2 ETL thickness. The open circuit voltage (V OC ) and fill factor (FF) are directly proportional to the TiO 2 ETL thickness while the 50 nm thick TiO 2 ETL shows the highest current density (J SC ) of 20.77 mA cm -2 . Our controlled results reveal that the room temperature RF-magnetron sputtered 50 nm-thick TiO 2 ETL photoelectrode exhibits a power conversion efficiency (PCE) in excess of 15%. The use of room temperature synthesis of the compact TiO 2 ETL by RF magnetron sputtering results in an enhancement of the device performance for cells prepared on flexible substrates. The champion flexible planar PSC based on this architecture exhibited a promising power conversion efficiency as high as 15.88%, featuring a high FF of 0.69 and V OC of 1.108 V with a negligible

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  18. Solar photocatalytic disinfection of E. coli and bacteriophages MS2, ΦX174 and PR772 using TiO2, ZnO and ruthenium based complexes in a continuous flow system.

    Science.gov (United States)

    Mac Mahon, Joanne; Pillai, Suresh C; Kelly, John M; Gill, Laurence W

    2017-05-01

    The performance of photocatalytic treatment processes were assessed using different photocatalysts against E. coli and bacteriophages MS2, ΦX174 and PR772, in a recirculating continuous flow compound parabolic collector system under real sunlight conditions. Suspended TiO 2 and ZnO nanoparticle powders and Tris(2,2'-bipyridyl)dichlororuthenium(II) hexahydrate in solution were tested separately, as well as in combination, using E. coli. For a 3-log reduction of E. coli in distilled water, inactivation rates in terms of cumulative dose were in the order Ru(bpy) 3 Cl 2 >(TiO 2 & Ru(bpy) 3 Cl 2 )>(ZnO & Ru(bpy) 3 Cl 2 )>ZnO>TiO 2 >photolysis. Reactivation of E. coli was observed following all trials despite the detection limit being reached, although the reactivated colonies were observed to be under stress and much slower growing when compared to original colonies. Treatment with Ru(bpy) 3 Cl 2 was also compared against standard photolysis of bacteriophages MS2, ΦX174 and PR772 with the order of photolytic inactivation for a 3-log reduction in terms of cumulative UV-A dose being ΦX174>PR772>MS2. However, MS2 was found to be the most susceptible bacteriophage to treatment with Ru(bpy) 3 Cl 2 , with complete removal of the phage observed within the first 15min of exposure. Ru(bpy) 3 Cl 2 also significantly improved inactivation rates for PR772 and ΦX174. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Electrospun Fe3O4/TiO2 hybrid nanofibers and their in vitro biocompatibility: prospective matrix for satellite cell adhesion and cultivation.

    Science.gov (United States)

    Amna, Touseef; Hassan, M Shamshi; Van Ba, Hoa; Khil, Myung-Seob; Lee, Hak-Kyo; Hwang, I H

    2013-03-01

    We report the fabrication of novel Fe3O4/TiO2 hybrid nanofibers with the improved cellular response for potential tissue engineering applications. In this study, Fe3O4/TiO2 hybrid nanofibers were prepared by facile sol-gel electrospinning using titanium isopropoxide and iron(III) nitrate nonahydrate as precursors. The obtained electrospun nanofibers were vacuum dried at 80 °C and then calcined at 500 °C. The physicochemical characterization of the synthesized composite nanofibers was carried out by scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy and X-ray diffraction pattern. To examine the in vitro cytotoxicity, satellite cells were treated with as-prepared Fe3O4/TiO2 and the viability of cells was analyzed by Cell Counting Kit-8 assay at regular time intervals. The morphological features of unexposed satellite cells and exposed to Fe3O4/TiO2 composite were examined with a phase contrast microscope whereas the quantification of cell viability was carried out via confocal laser scanning microscopy. The morphology of the cells attached to hybrid matrix was observed by Bio-SEM. Cytotoxicity experiments indicated that the satellite cells could attach to the Fe3O4/TiO2 composite nanofibers after being cultured. We observed that Fe3O4-TiO2 composite nanofibers could support cell adhesion and growth. Results from this study therefore suggest that Fe3O4/TiO2 composite scaffold with small diameters (approximately 200 nm) can mimic the natural extracellular matrix well and provide possibilities for diverse applications in the field of tissue engineering and regenerative medicine. Copyright © 2012 Elsevier B.V. All rights reserved.

  20. 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

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

    Directory of Open Access Journals (Sweden)

    Imelda Fajriati

    2014-10-01

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

  2. 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

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  4. Development of Dye-Sensitized Solar Cells with Sputtered N-Doped TiO2 Thin Films: From Modeling the Growth Mechanism of the Films to Fabrication of the Solar Cells

    Directory of Open Access Journals (Sweden)

    D. A. Duarte

    2014-01-01

    Full Text Available In this paper, nitrogen-doped TiO2 thin films were deposited by DC reactive sputtering at different doping levels for the development of dye-sensitized solar cells. The mechanism of film growth during the sputtering process and the effect of the nitrogen doping on the structural, optical, morphological, chemical, and electronic properties of the TiO2 were investigated by numerical modeling and experimental methods. The influence of the nitrogen doping on the working principle of the prototypes was investigated by current-voltage relations measured under illuminated and dark conditions. The results indicate that, during the film deposition, the control of the oxidation processes of the nitride layers plays a fundamental role for an effective incorporation of substitutional nitrogen in the film structure and cells built with nitrogen-doped TiO2 have higher short-circuit photocurrent in relation to that obtained with conventional DSSCs. On the other hand, DSSCs built with nondoped TiO2 have higher open-circuit voltage. These experimental observations indicate that the incorporation of nitrogen in the TiO2 lattice increases simultaneously the processes of generation and destruction of electric current.

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

    Science.gov (United States)

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

    2018-01-01

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

  6. A photocatalytic approach in micro arc oxidation of WO3-TiO2 nano porous semiconductors under pulse current

    International Nuclear Information System (INIS)

    Bayati, M.R.; Golestani-Fard, F.; Moshfegh, A.Z.; Molaei, R.

    2011-01-01

    Graphical abstract: WO3-TiO2 layers were fabricated via microarc oxidation process and effect of the electrical current type on their photocatalytic performance under UV and visible illuminations was investigated. Highlights: → WO3-TiO2 layers were grown by MAO under pulse current for the first time. → Effect of the frequency and duty cycle on properties of the layers was studied. → A correlation between catalytic performance and growth conditions was proposed. - Abstract: Since ultraviolet (UV) irradiation cannot be applied for a long time in practical applications, it is necessary to develop a narrow band gap photocatalyst to decompose environmental pollutants under visible irradiation. In this research, (WO 3 ) x -(TiO 2 ) 1-x nano-porous layers were fabricated by micro arc oxidation (MAO) and influence of the electrical current type on their physical and chemical properties was investigated. Morphological studies, performed by SEM technique, revealed that pore size and roughness decreased with the frequency and increased with the duty cycle. The pulse-grown layers had a finer structure when compared to those fabricated under direct current. XRD and XPS results showed that the layers consisted of anatase, rutile, and tungsten oxide phases. Applying pulse current resulted in higher anatase relative contents. Band gap energies of the MAO-grown TiO 2 and WO 3 -TiO 2 layers were respectively measured as 3.14 and 2.96 eV. The layers fabricated under pulse current exhibited higher photoactivity under ultraviolet and visible illuminations as compared to the layers grown under direct current. Methylene blue (MB) was used as a model material to examine photocatalytic performance of the layers. Maximum MB-photodegradation reaction rate constants over the pulse-synthesized WO 3 -TiO 2 layers were measured as 0.0269 and 0.0129 min -1 for ultraviolet and visible irradiations. For layers grown under direct current, the rate constants were lower, i.e. 0.0228 and 0

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

    Science.gov (United States)

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

    2013-04-01

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

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

    International Nuclear Information System (INIS)

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

    2010-01-01

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

  9. Ag and CdS nanoparticles co-sensitized TiO2 nanotubes for enhancing visible photoelectrochemical performance

    International Nuclear Information System (INIS)

    Wang Qingyao; Yang Xiuchun; Liu Dan; Chi Lina; Hou Junwei

    2012-01-01

    Highlights: ► Ag and CdS nanoparticles co-sensitized TiO 2 nanotubes were fabricated by the SILAR method. ► The co-sensitization expands the photoresponse range of TiO 2 NTs to 668.7 nm. ► Visible light photocurrents and photocatalytic activities of CdS–Ag/TiO 2 NTs were studied. ► The electron transfer mechanism of CdS–Ag/TiO 2 NTs was proposed. - Abstract: The Ag and CdS nanoparticles co-sensitization of TiO 2 nanotubes (CdS–Ag/TiO 2 NTs) were prepared by successive ionic layer adsorption and reaction (SILAR) technique. The phase composition, morphology and optical property were characterized by the X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV–vis diffusion reflection spectroscopy (DRS). The co-modification of Ag and CdS nanoparticles expanded the photoresponse range of TiO 2 NTs from ultraviolet region to 668.7 nm, and the CdS–Ag/TiO 2 NTs prepared by SILAR deposition of 5 cycles exhibited higher visible photocurrent and stability against photocorrosion. The detailed electrons transfer mechanism of CdS–Ag/TiO 2 NTs was proposed, and photocatalytic activity toward degradation of methyl orange (MO) under visible-light irradiation was also investigated.

  10. Exciton confinement in strain-engineered metamorphic InAs/I nxG a1 -xAs quantum dots

    Science.gov (United States)

    Khattak, S. A.; Hayne, M.; Huang, J.; Vanacken, J.; Moshchalkov, V. V.; Seravalli, L.; Trevisi, G.; Frigeri, P.

    2017-11-01

    We report a comprehensive study of exciton confinement in self-assembled InAs quantum dots (QDs) in strain-engineered metamorphic I nxG a1 -xAs confining layers on GaAs using low-temperature magnetophotoluminescence. As the lattice mismatch (strain) between QDs and confining layers (CLs) increases from 4.8% to 5.7% the reduced mass of the exciton increases, but saturates at higher mismatches. At low QD-CL mismatch there is clear evidence of spillover of the exciton wave function due to small localization energies. This is suppressed as the In content x in the CLs decreases (mismatch and localization energy increasing). The combined effects of low effective mass and wave-function spillover at high x result in a diamagnetic shift coefficient that is an order of magnitude larger than for samples where In content in the barrier is low (mismatch is high and localization energy is large). Finally, an anomalously small measured Bohr radius in samples with the highest x is attributed to a combination of thermalization due to low localization energy, and its enhancement with magnetic field, a mechanism which results in small dots in the ensemble dominating the measured Bohr radius.

  11. Electrospun Fe3O4/TiO2 hybrid nanofibers and their in vitro biocompatibility: Prospective matrix for satellite cell adhesion and cultivation

    International Nuclear Information System (INIS)

    Amna, Touseef; Hassan, M. Shamshi; Van Ba, Hoa; Khil, Myung-Seob; Lee, Hak-Kyo; Hwang, I.H.

    2013-01-01

    We report the fabrication of novel Fe 3 O 4 /TiO 2 hybrid nanofibers with the improved cellular response for potential tissue engineering applications. In this study, Fe 3 O 4 /TiO 2 hybrid nanofibers were prepared by facile sol–gel electrospinning using titanium isopropoxide and iron(III) nitrate nonahydrate as precursors. The obtained electrospun nanofibers were vacuum dried at 80 °C and then calcined at 500 °C. The physicochemical characterization of the synthesized composite nanofibers was carried out by scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy and X-ray diffraction pattern. To examine the in vitro cytotoxicity, satellite cells were treated with as-prepared Fe 3 O 4 /TiO 2 and the viability of cells was analyzed by Cell Counting Kit-8 assay at regular time intervals. The morphological features of unexposed satellite cells and exposed to Fe 3 O 4 /TiO 2 composite were examined with a phase contrast microscope whereas the quantification of cell viability was carried out via confocal laser scanning microscopy. The morphology of the cells attached to hybrid matrix was observed by Bio-SEM. Cytotoxicity experiments indicated that the satellite cells could attach to the Fe 3 O 4 /TiO 2 composite nanofibers after being cultured. We observed that Fe 3 O 4 –TiO 2 composite nanofibers could support cell adhesion and growth. Results from this study therefore suggest that Fe 3 O 4 /TiO 2 composite scaffold with small diameters (approximately 200 nm) can mimic the natural extracellular matrix well and provide possibilities for diverse applications in the field of tissue engineering and regenerative medicine. Highlights: ► We report fabrication of novel Fe 3 O 4 /TiO 2 hybrid nanofibers by facile electrospinning. ► The utilized satellite cells were isolated from native Korean Hanwoo cattle. ► Fe 3 O 4 /TiO 2 composite with small diameters (∼ 200 nm) can mimic the natural ECM well. ► Fe 3 O 4 /TiO 2

  12. 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.

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

    Science.gov (United States)

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

    2017-08-01

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

  14. 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

  15. 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.

  16. 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)

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

    OpenAIRE

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

    2015-01-01

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

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

    Science.gov (United States)

    Yoon, Yeoungchin; Park, Jeongwon

    2018-04-01

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

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

    Directory of Open Access Journals (Sweden)

    Ezhil Arasi S.

    2017-04-01

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

  20. Dielectric and microwave absorption properties of TiO_2/Al_2O_3 coatings and improved microwave absorption by FSS incorporation

    International Nuclear Information System (INIS)

    Yang, Zhaoning; Luo, Fa; Hu, Yang; Duan, Shichang; Zhu, Dongmei; Zhou, Wancheng

    2016-01-01

    In this paper, TiO_2/Al_2O_3 ceramic coatings were prepared by atmospheric plasma spraying (APS) technique. The phase composition and morphological characterizations of the synthesized TiO_2/Al_2O_3 powders and coatings were performed by X-ray diffraction and scanning electron microscopy (SEM), respectively. The dielectric properties of these coatings were discussed in the frequency range from 8.2 to 12.4 GHz (X-band). By calculating the microwave-absorption as a single-layer absorber, their microwave absorption properties were investigated at different content and thickness in details. Furthermore, by combination of the Frequency selective surface (FSS) and ceramic coatings, a double absorption band of the reflection loss spectra had been observed. The microwave absorbing properties of coatings both in absorbing intensity and absorbing bandwidth were improved. The reflection loss values of TiO_2/Al_2O_3 coatings exceeding −10 dB (larger than 90% absorption) can be obtained in the whole frequency range of X-band with 17 wt% TiO_2 content when the coating thickness is 2.3 mm. - Highlights: • Dielectric properties of TiO_2/Al_2O_3 ceramics fabricated by APS technique are reported for the first time. • Microwave absorption properties of TiO_2/Al_2O_3 composites are improved by FSS. • Reflection loss values exceeding −10 dB can be obtained in the whole X-band when coating thickness is 2.3 mm.

  1. Nanoporous TiO_2 electrode grown by laser ablation of titanium in air at atmospheric pressure and room temperature

    International Nuclear Information System (INIS)

    Białous, Anna; Gazda, Maria; Grochowska, Katarzyna; Atanasov, Petar; Dikovska, Anna; Nedyalkov, Nikolay; Reszczyńska, Joanna; Zaleska-Medynska, Adriana; Śliwiński, Gerard

    2016-01-01

    Recently, fabrication of the nanoporous TiO_2 photoelectrode on metal foils by means of sputtering of the Ti film on preheated metal substrate followed by the TiO_2 deposition (doctor blade technique) and sintering represents the frequently applied technique. This is despite the relatively complicated procedure and number of parameters to be controlled in order to fabricate films of required properties. In this work an approach is applied and discussed in which the nanoporous TiO_2 electrode is fabricated under conditions similar to pulsed laser deposition but with the deposit formed directly on the ablated target at atmospheric pressure and room temperature. The titanium dioxide thin film is grown by ablation of the Ti foil with the nanosecond UV laser (266 nm) at fluence up to 1.5 J/cm"2. The rutile–anatase phase transformation takes place during this one-step process and no thermal pre-and post-treatment of the deposit is needed. In samples produced in air, the presence of mixed phases of the non-stoichiometric anatase (> 70%), rutile and negligible amount of TiN is consistently confirmed by the X-ray diffraction, energy-dispersive X-ray and Raman spectra. For applications of the reported films as electrode material in the third generation photovoltaic cells, the use of industrial lasers could significantly improve the process efficiency. - Highlights: • TiO_2 films via laser ablation of Ti in air under standard temperature and pressure conditions • Nanoporous crystalline structure from one-step process • Anatase content > 70% in the mixed phase film

  2. 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.

  3. D-sorbitol-induced phase control of TiO2 nanoparticles and its application for dye-sensitized solar cells

    Science.gov (United States)

    Shaikh, Shoyebmohamad F.; Mane, Rajaram S.; Min, Byoung Koun; Hwang, Yun Jeong; Joo, Oh-Shim

    2016-02-01

    Using a simple hydrothermal synthesis, the crystal structure of TiO2 nanoparticles was controlled from rutile to anatase using a sugar alcohol, D-sorbitol. Adding small amounts of D-sorbitol to an aqueous TiCl4 solution resulted in changes in the crystal phase, particle size, and surface area by affecting the hydrolysis rate of TiCl4. These changes led to improvements of the solar-to-electrical power conversion efficiency (η) of dye-sensitized solar cells (DSSC) fabricated using these nanoparticles. A postulated reaction mechanism concerning the role of D-sorbitol in the formation of rutile and anatase was proposed. Fourier-transform infrared spectroscopy, 13C NMR spectroscopy, and dynamic light scattering analyses were used to better understand the interaction between the Ti precursor and D-sorbitol. The crystal phase and size of the synthesized TiO2 nanocrystallites as well as photovoltaic performance of the DSSC were examined using X-ray diffraction, Raman spectroscopy, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and photocurrent density-applied voltage spectroscopy measurement techniques. The DSSC fabricated using the anatase TiO2 nanoparticles synthesized in the presence of D-sorbitol, exhibited an enhanced η (6%, 1.5-fold improvement) compared with the device fabricated using the rutile TiO2 synthesized without D-sorbitol.

  4. Hydrothermal fabrication of few-layer MoS2 nanosheets within nanopores on TiO2 derived from MIL-125(Ti) for efficient photocatalytic H2 evolution

    Science.gov (United States)

    Ye, Fei; Li, Houfen; Yu, Hongtao; Chen, Shuo; Quan, Xie

    2017-12-01

    Protons tend to bond strongly with unsaturated-coordinate S element located at the edge of nano-MoS2 and are consequently reduced to H2. Therefore, increasing the active S atoms quantity will be a feasible approach to enhance hydrogen evolution. Herein we developed a porous TiO2 derived from metal organic frameworks (MOFs) as scaffold to restrict the growth and inhibit the aggregation of MoS2 nanosheets. As a result, the thickness of the prepared MoS2 nanosheets was less than 3 nm (1-4 layers), with more edges and active S atoms being exposed. This few-layer MoS2-porous TiO2 exhibits a H2 evolution rate of 897.5 μmol h-1 g-1, which is nearly twice as much as free-stand MoS2 nanosheets and twenty times more than physical mixture of MoS2 with porous TiO2. The high performance is attributed to that more active edge sites in few-layer MoS2-porous TiO2 are exposed than pure MoS2. This work provides a new method to construct MOFs derived porous structures for controlling MoS2 to expose active sites for HER.

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

    Directory of Open Access Journals (Sweden)

    Seigo Ito

    2012-01-01

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

  6. Wet-Chemical Preparation of TiO2-Based Composites with Different Morphologies and Photocatalytic Properties

    Directory of Open Access Journals (Sweden)

    Liqin Xiang

    2017-10-01

    Full Text Available TiO2-based composites have been paid significant attention in the photocatalysis field. The size, crystallinity and nanomorphology of TiO2 materials have an important effect on the photocatalytic efficiency. The synthesis and photocatalytic activity of TiO2-based materials have been widely investigated in past decades. Based on our group’s research works on TiO2 materials, this review introduces several methods for the fabrication of TiO2, rare-earth-doped TiO2 and noble-metal-decorated TiO2 particles with different morphologies. We focused on the preparation and the formation mechanism of TiO2-based materials with unique structures including spheres, hollow spheres, porous spheres, hollow porous spheres and urchin-like spheres. The photocatalytical activity of urchin-like TiO2, noble metal nanoparticle-decorated 3D (three-dimensional urchin-like TiO2 and bimetallic core/shell nanoparticle-decorated urchin-like hierarchical TiO2 are briefly discussed.

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

    Science.gov (United States)

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

    2014-02-01

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

  8. Dry-spray deposition of TiO2 for a flexible dye-sensitized solar cell (DSSC) using a nanoparticle deposition system (NPDS).

    Science.gov (United States)

    Kim, Min-Saeng; Chun, Doo-Man; Choi, Jung-Oh; Lee, Jong-Cheon; Kim, Yang Hee; Kim, Kwang-Su; Lee, Caroline Sunyong; Ahn, Sung-Hoon

    2012-04-01

    TiO2 powders were deposited on indium tin oxide (ITO) coated polyethylene terephthalate (PET) substrates for application to the photoelectrode of a dye-sensitized solar cell (DSSC). In the conventional DSSC manufacturing process, a semiconductor oxide such as TiO2 powder requires a sintering process at higher temperature than the glass transition temperature (T(g)) of polymers, and thus utilization of flexible polymer substrates in DSSC research has been constrained. To overcome this restriction related to sintering, we used a nanoparticle deposition system (NPDS) that could produce a thin coating layer through a dry-spray method under atmospheric pressure at room temperature. The powder was sprayed through a slit-type nozzle having a 0.4 x 10 mm2 rectangular outlet. In order to determine the deposited TiO2 thickness, five kinds of TiO2 layered specimens were prepared, where the specimens have single and double layer structures. Deposited powders on the ITO coated PET substrates were observed using FE-SEM and a scan profiler The thicker TiO2 photoelectrode with a DSSC having a double layer structure showed higher energy efficiency than the single layer case. The highest fabricated flexible DSSC displayed a short circuit current density J(sc) = 1.99 mA cm(-2), open circuit voltage V(oc) = 0.71 V, and energy efficiency eta = 0.94%. These results demonstrate the possibility of utilizing the dry-spray method to fabricate a TiO2 layer on flexible polymer substrates at room temperature under atmospheric pressure.

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

    International Nuclear Information System (INIS)

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

    2012-01-01

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

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

    Science.gov (United States)

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

    2017-11-01

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

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

    Institute of Scientific and Technical Information of China (English)

    王婵; 黄彦

    2014-01-01

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

  12. Graphene-spindle shaped TiO2 mesocrystal composites: Facile synthesis and enhanced visible light photocatalytic performance

    International Nuclear Information System (INIS)

    Yang, Xiaofei; Qin, Jieling; Li, Yang; Zhang, Rongxian; Tang, Hua

    2013-01-01

    Highlights: • Graphene-TiO 2 mesocrystal composites were fabricated via a facile approach. • Graphene sheets were decorated with spindle-like TiO 2 mesocrystals. • Graphene causes enhanced light absorbance and visible light photocatalytic activity. • Oxygen-containing radicals are believed to responsible for its improved activity. -- Abstract: Graphene (GR)-TiO 2 mesocrystal composites were prepared by a facile template-free process based on the combination of sol–gel and solvothermal methods, and were characterized using field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Raman spectroscopy, UV–vis diffuse reflectance spectroscopy (UV–vis DRS), nitrogen absorption and electron spin resonance (ESR). Visible light photocatalytic performance of GR-TiO 2 composites was evaluated for photocatalytic degradation of organic dye Rhodamine B. It was found that the amount of graphene oxide (GO) added obviously affects morphologies of TiO 2 mesocrystals and photocatalytic activities of as-prepared nanocomposites. Composites prepared in the presence of different amounts of GO all exhibit higher photocatalytic activity than pure TiO 2 mesocrystals and P25, the composite obtained by using 20 mg GO presents the most uniform TiO 2 mesocrystals in the composite and shows the highest photocatalytic efficiency. The mechanism for the generation of TiO 2 mesocrystals in the GR-TiO 2 composite is proposed and possible reasons for the enhancement in visible light photocatalytic efficiency are also discussed

  13. Growth of TiO2 Thin Film on Various Substrates using RF Magnetron Sputtering

    International Nuclear Information System (INIS)

    Ali, Riyaz Ahmad Mohamed; Nayan, Nafarizal

    2011-01-01

    The conductivity of Titanium Dioxide (TiO 2 ) thin film fabricated using Radio Frequency (RF) Magnetron Sputtering on Silicon (Si), Indium doped--Tin Oxide (ITO) and microscope glass (M) substrates is presented in this paper. The dependant of thin film thickness and type of substrate been discussed. TiO 2 was deposited using Ti target in Ar+O 2 (45:10) mixture at 250 W for 45, 60, 75, 90, 105 and 120 minute. Resultant thickness varies from 295 nm to 724 nm with deposition rate 6.4 nm/min. On the other hand, resistivity, Rs value for ITO substrate is between 5.72x10 -7 to 1.54x10 -6 Ω.m, Si substrate range is between 3.52x10 -6 to 1.76x10 -5 Ω.m and M substrate range is between 99 to 332 Ω.m. The value of resistivity increases with the thickness of the thin film.

  14. Crystallisation of Ba1-xSrxZn2Si2O7 from BaO/SrO/ZnO/SiO2 glass with different ZrO2 and TiO2 concentrations

    Science.gov (United States)

    Vladislavova, Liliya; Kracker, Michael; Zscheckel, Tilman; Thieme, Christian; Rüssel, Christian

    2018-04-01

    The effect of different nucleation agents such as ZrO2 and TiO2 was investigated for a first time with respect to their crystallisation behaviour in the glass system BaO-SrO-ZnO-SiO2. In all studied glasses, a Ba1-xSrxZn2Si2O7 (0.1 ≤ x ≤ 0.9) solid solution crystallized. This phase was first described in 2015 to possess a similar structure as the high temperature phase of BaZn2Si2O7 and a thermal expansion close to zero or even negative. It may find applications e.g. as cook panels, telescope mirrors, and furnace windows. Kinetic parameters of the crystallisation process were determined by supplying different heating rates in a differential scanning calorimeter (DSC). The results were evaluated using the equations of Ozawa and Kissinger with respect to the activation energies. Furthermore, the Ozawa method was used for the determination of Avrami parameters, which provides further information on the nucleation and crystallisation processes. Scanning electron microscopy including electron backscatter diffraction (EBSD) was used to characterise the microstructure, to determine the crystallite size and the crystal orientation. For the characterisation of the occurring crystalline phases, X-ray diffraction was used.

  15. Electrospinning processed nanofibrous TiO2 membranes for photovoltaic applications

    Science.gov (United States)

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

    2006-02-01

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

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  17. Investigation of the spin-lattice coupling in M n3G a1 -xS nxN antiperovskites

    Science.gov (United States)

    Shi, Kewen; Sun, Ying; Colin, Claire V.; Wang, Lei; Yan, Jun; Deng, Sihao; Lu, Huiqing; Zhao, Wenjun; Kazunari, Yamaura; Bordet, Pierre; Wang, Cong

    2018-02-01

    The magnetovolume effects (MVEs) of M n3G a1 -xS nxN antiperovskite compounds have been investigated by means of neutron powder diffraction. Increasing the Sn-doping content at the Ga site leads to the broadening of the magnetic phase transition temperature range and the thermal expansion behavior changes from negative to positive. We establish the relationship between the square of the ordered magnetic moment m2 and the volume variation Δ ωm for the antiferromagnetic phase (Γ5 g magnetic structure with rhombohedral symmetry R 3 ¯m ). The temperature variations of Δ ωm(T ) , m2(T ) and the magnetoelastic coupling constant C (T ) are also quantitatively analyzed according to the itinerant-electron theory. Moreover, the increase of the phonon contribution to the thermal expansion induced by Sn doping and the corresponding decrease of dm/dT are revealed to be the key parameters for tuning the MVEs. Our results allow elucidating and quantifying the mechanism of the spin-lattice coupling and can be used to design magnetic functional materials with controlled thermal expansion behaviors for specific applications.

  18. Elastic Properties and the Band Gap of AlNxP1-x Semiconductor Alloy: A Comparative Study of Various Ab Initio Approaches

    Directory of Open Access Journals (Sweden)

    M. P. Polak

    2016-01-01

    Full Text Available Structural and elastic properties of AlNxP1-x, a novel semiconductor alloy, are studied from the first principles in both zinc-blende and wurtzite structures. Performances of the finite difference (FD method and the density functional perturbation theory (DFPT are tested and compared. Both of these methods are applied to two different approaches of alloy simulation, a supercell of 16 and 32 atoms (for zinc-blende and wurtzite structures, resp. and the alchemical mixing (AM method, where the pseudopotentials are mixed in an appropriate way to form an alloy. All elastic properties, including the elastic tensors, elastic moduli, Poisson’s ratio, B/G, and relaxation coefficient, as well as lattice parameters are calculated using all said methods. Conclusions about the use of the approaches investigated in this paper and about their performance are drawn. In addition, in both crystal structures, the band gap is studied in the whole composition range using the MBJLDA functional. The band gap bowings are unusually high, which confirms earlier reports.

  19. 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

  20. The Effects of Oxidation Temperature on the Microstructure and Photocatalytic Activity of the TiO2 Coating

    Directory of Open Access Journals (Sweden)

    Xinxin TANG

    2017-08-01

    Full Text Available Titanium coatings were prepared on the surface of 1mm ZrO2 balls by mechanical ball mill, then the coatings were oxidized to photocatalytic TiO2 films at 400 ~ 600 °C. X-Ray Diffraction, Scanning Electron Microscope, Energy Dispersive Spectroscopy and Optical Microscope were used to analyze the microstructure and crystal form of the films. The photocatalytic activity of the samples was also evaluated. After that, the effects of oxidation temperature on the microstructure and photocatalytic activity of the films were discussed. The results show that the fabricated coatings are uneven, with average thickness of 60 μm. In the process of oxidation, oxygen is imported into the inner coatings by the gaps existed in the Ti coatings, which makes the Ti particles oxidize from surface to core, finally the films with TiO2 + Ti composite microstructure are obtained. The films oxidized at 500 °C have the best photocatalytic performance with the degradation rate of methyl orange solution 79.08 %, this owing to the existence of anatase and the TiO2+Ti composite microstructure. The result will provide theoretical basis for the fabrication of efficient photocatalytic film.DOI: http://dx.doi.org/10.5755/j01.ms.23.2.15590

  1. 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.

  2. 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%.

  3. Spectroscopic ellipsometry analysis of GaAs1-xNx layers grown by molecular beam epitaxy

    International Nuclear Information System (INIS)

    Ben Sedrine, N.; Rihani, J.; Stehle, J.L.; Harmand, J.C.; Chtourou, R.

    2008-01-01

    In this work, we present the effect of nitrogen incorporation on the dielectric function of GaAsN samples, grown by molecular beam epitaxy (MBE) followed by a rapid thermal annealing (for 90 s at 680 deg. C). The GaAs 1-x N x samples with N content up to 1.5% (x = 0.0%, 0.1%, 0.5%, 1.5%), are investigated using room temperature spectroscopic ellipsometry (SE). The optical transitions in the spectral region around 3 eV are analyzed by fitting analytical critical point line shapes to the second derivative of the dielectric function. It was found that the features associated with E 1 and E 1 + Δ 1 transitions are blue-shifted and become less sharp with increasing nitrogen incorporation, in contrast to the case of E 0 transition energy in GaAs 1-x N x . An increase of the split-off Δ 1 energy with nitrogen content was also obtained, in agreement to results found with MOVPE GaAs 1-x N x grown samples

  4. Combined in situ small and wide angle X-ray scattering studies of TiO2 nano-particle annealing to 1023 K

    DEFF Research Database (Denmark)

    Kehres, Jan; Andreasen, Jens Wenzel; Krebs, Frederik C

    2010-01-01

    Combined in situ small- and wide-angle X-ray scattering (SAXS/WAXS) studies were performed in a recently developed laboratory setup to investigate the dynamical properties of dry oleic acid-capped titanium dioxide nanorods during annealing in an inert gas stream in a temperature interval of 298-1...

  5. One-step route to a hybrid TiO2/TixW1−xN nanocomposite by in situ selective carbothermal nitridation

    Directory of Open Access Journals (Sweden)

    Zoë Schnepp, Martin J Hollamby, Masahiko Tanaka, Yoshitaka Matsushita, Yoshio Katsuya and Yoshio Sakka

    2012-01-01

    Full Text Available Metal oxide/nitride nanocomposites have many existing and potential applications, e.g. in energy conversion or ammonia synthesis. Here, a hybrid oxide/nitride nanocomposite (anatase/TixW1−xN was synthesized by an ammonia-free sol–gel route. Synchrotron x-ray diffraction, complemented with electron microscopy and thermogravimetric analysis, was used to study the structure, composition and mechanism of formation of the nanocomposite. The nanocomposite contained nanoparticles (<5 nm diameter of two highly intermixed phases. This was found to arise from controlled nucleation and growth of a single oxide intermediate from the gel precursor, followed by phase separation and in situ selective carbothermal nitridation. Depending on the preparation conditions, the composition varied from anatase/TixW1−xN at low W content to an isostructural mixture of Ti-rich and W-rich TixW1−xN at high W content. In situ selective carbothermal nitridation offers a facile route to the synthesis of nitride-oxide nanocomposites. This conceptually new approach is a significant advance from previous methods, which generally require ammonolysis of a pre-synthesized oxide.

  6. Novel bamboo structured TiO2 nanotubes for energy storage/production applications

    Science.gov (United States)

    Samuel, J. J.; Beh, K. P.; Cheong, Y. L.; Yusuf, W. A. A.; Yam, F. K.

    2018-04-01

    Nanostructured TiO2 received much attention owing to its high surface-to-volume ratio, which can be advantageous in energy storage and production applications. However, the increase in energy consumption at present and possibly the foreseeable future has demanded energy storage and production devices of even higher performance. A direct approach would be manipulating the physical aspects of TiO2 nanostructures, particularly, nanotubes. In this work, dual voltage anodization system has been implemented to fabricate bamboo shaped TiO2 nanotubes, which offers even greater surface area. This unique nanostructure would be used in Dye Sensitized Solar Cell (DSSC) fabrication and its performance will be evaluated and compared along other forms of TiO2 nanotubes. The results showed that bamboo shaped nanotubes indeed are superior morphologically, with an increase of efficiency of 107% at 1.130% efficiency when compared to smooth walled nanotubes at 0.546% efficiency.

  7. Structural, electronic, mechanical, thermal and optical properties of B(P,As)1-xNx; (x = 0, 0.25, 0.5, 0.75, 1) alloys and hardness of B(P,As) under compression using DFT calculations

    Science.gov (United States)

    Viswanathan, E.; Sundareswari, M.; Jayalakshmi, D. S.; Manjula, M.; Krishnaveni, S.

    2017-09-01

    First principles calculations are carried out in order to analyze the structural, electronic, mechanical, thermal and optical properties of BP and BAs compounds by ternary alloying with nitrogen namely B(P,As)1-xNx (x = 0.25, 0.5, 0.75) alloys at ambient condition. Thereby we report the mechanical and thermal properties of B(P,As)1-xNx (x = 0.25, 0.5, 0.75) alloys namely bulk modulus, shear modulus, Young's modulus, hardness, ductile-brittle nature, elastic wave velocity, Debye temperature, melting point, etc.; optical properties of B(P)1-xNx (x = 0.25, 0.5, 0.75) and B(As)1-xNx (x = 0.25, 0.75) alloys namely the dielectric function of real and imaginary part, refractive index, extinction coefficient and reflectivity and the hardness profile of the parent compounds BP and BAs under compression. The charge density plot, density of states histograms and band structures are plotted and discussed for all the ternary alloys of the present study. The calculated results agree very well with the available literature. Analysis of the present study reveals that the ternary alloy combinations namely BP.25N.75 and BAs.25N.75 could be superhard materials; hardness of BP and BAs increases with compression.

  8. Solvothermal synthesis of TiO2 nanocrystals with {001} facets using titanic acid nanobelts for superior photocatalytic activity

    Science.gov (United States)

    Cao, Yuhui; Zong, Lanlan; Li, Qiuye; Li, Chen; Li, Junli; Yang, Jianjun

    2017-01-01

    Anatase TiO2 nanocrystals exposed with {001} facets were fabricated by solvothermal strategy in HF-C4H9OH mixed solution, using titanic acid nanobelts (TAN) as a precursor. The shape of TAN is a long flat plane with a high aspect ratio, and F- is easily adsorbed on the surface of the nanobelts, inducing a higher exposure of {001} facet of TiO2 nanoparticles during the structure reorganization. The exposed percentage of {001} facets could vary from 40 to 77% by adjusting the amount of HF. The as-prepared samples were characterized by transmission electron microscopy, N2 adsorption-desorption isotherms, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscope. The photocatalytic measurement showed that TiO2 nanocrystals with 77% {001} facets exhibited much superior photocatalytic activity for photodegradation of methyl orange, methylene blue, and rhodamine B. And what's more, the mineralization rate of methyl orange was as high as 96% within 60 min. The photocatalytic enhancement is due to a large amount of the high energetic {001} facets exposing, the special truncated octahedral morphology and a stronger ability for dyes adsorption.

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

    International Nuclear Information System (INIS)

    Zhu Yaofeng; Fu Yaqin; Ni Qingqing

    2011-01-01

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

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

    Science.gov (United States)

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

    2010-02-01

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

  11. Effect of titanium dioxide (TiO2) on largely improving solar reflectance and cooling property of high density polyethylene (HDPE) by influencing its crystallization behavior

    International Nuclear Information System (INIS)

    Wang, Shichao; Zhang, Jun

    2014-01-01

    Highlights: • HDPE/TiO 2 composites have more perfect crystal structure. • Refractive index is the key factor affecting the final solar reflectance. • HDPE/TiO 2 composites can achieve high solar reflectance. • The real cooling property is in accordance with solar reflectance. - Abstract: In this study, the different crystal forms of titanium dioxide (TiO 2 ) were added into high density polyethylene (HDPE) to fabricate cool material. Crystal structure, crystallization behavior, crystal morphology were investigated by wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and polarized optical microscope (POM). Scanning electron microscope (SEM) was applied to observe dispersion of TiO 2 particles in the HDPE matrix and the cross section morphology. The solar reflectance and actual cooling property were evaluated by UV–Vis–NIR spectrometer and a self-designed device. By adding TiO 2 particles into HDPE matrix, the polymer chain could crystallize into more perfect and thermal stable lamella. The presence of TiO 2 particles dramatically increased the number of nucleation site therefore decreased the crystal size. The subsequent solar reflectance was related to the degree of crystallinity, the spherulite size of HDPE, refractive index, and distribution of TiO 2 particles in HDPE matrix. It was found the rutile TiO 2 could largely improve the total solar reflectance from 28.2% to 51.1%. Finally, the temperature test showed that the composites had excellent cooling property, which was in accordance with solar reflectance result

  12. Photocatalytic properties of porous TiO2/Ag thin films

    International Nuclear Information System (INIS)

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

    2008-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Mitra eVasei

    2014-07-01

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

  14. Study of paramagnetic defect centers in as-grown and annealed TiO2 anatase and rutile nanoparticles by a variable-temperature X-band and high-frequency (236 GHz) EPR.

    Science.gov (United States)

    Misra, S K; Andronenko, S I; Tipikin, D; Freed, J H; Somani, V; Prakash, Om

    2016-03-01

    Detailed EPR investigations on as-grown and annealed TiO 2 nanoparticles in the anatase and rutile phases were carried out at X-band (9.6 GHz) at 77, 120-300 K and at 236 GHz at 292 K. The analysis of EPR data for as-grown and annealed anatase and rutile samples revealed the presence of several paramagnetic centers: Ti 3+ , O - , adsorbed oxygen (O 2 - ) and oxygen vacancies. On the other hand, in as-grown rutile samples, there were observed EPR lines due to adsorbed oxygen (O 2 - ) and the Fe 3+ ions in both Ti 4+ substitutional positions, with and without coupling to an oxygen vacancy in the near neighborhood. Anatase nanoparticles were completely converted to rutile phase when annealed at 1000° C, exhibiting EPR spectra similar to those exhibited by the as-grown rutile nanoparticles. The high-frequency (236 GHz) EPR data on anatase and rutile samples, recorded in the region about g = 2.0 exhibit resolved EPR lines, due to O - and O 2 - ions enabling determination of their g-values with higher precision, as well as observation of hyperfine sextets due to Mn 2+ and Mn 4+ ions in anatase.

  15. 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%.

  16. 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.

  17. Small angle X-ray scattering by TiO2/ZrO2 mixed oxide particles and a Synroc precursor

    International Nuclear Information System (INIS)

    Gazeau, D.; Zemb, T.; Amal, R.; Bartlett, J.

    1992-09-01

    This high resolution small angle X-ray scattering study of a concentrated oxide sol, precursor of the SYNROC matrix for the storage of the high level radioactive waste, evidences a locally cylindrical microstructure. Locally, nanometric cylinders show disordered axis with some concentration dependent connections. This microstructure explains the paradoxal stability of this oxide dispersions upon the addition of concentrated acidic solutions. This stability has a steric origin and electrostatic repulsions are not needed. The addition of aluminium to the initial titanium-zirconium mixture enhances branching on the locally cylindrical microstructure. Finally, we show that the solid powder obtained after calcination (drying) of the sol has the same specific area (∼ 1000 m 2 /g) than the sol. (Author). 23 refs., 7 figs., 1 tab

  18. 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.

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

    Directory of Open Access Journals (Sweden)

    Sigrid Bernstorff

    2010-11-01

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

  20. Catalysis of a Nanometre Solid Super Acid of SO42-/TiO2 on the Thermal Decomposition of Ammonium Nitrate

    OpenAIRE

    Song, Xiaolan; Wang, Yi; Song, Dan; An, Chongwei; Wang, Jingyu

    2016-01-01

    Raw TiO2 nanoparticles were prepared using the hydroly‐ sis of TiCl4. The nanoparticles were subjected to a surface treatment in diluted sulphuric acid and, subsequently, calcined at different temperatures. Then, a type of super solid acid (SO42-/TiO2) with particle sizes of 20∼30 nm was fabricated. The catalysis of SO42-/TiO2 on the thermolysis of ammonium nitrate (AN) was probed using thermal analysis. For SO42-/TiO2 (AN doped with 3%SO42-/TiO2), the onset temperature decreased by 19°C and ...

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  2. 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.

  3. Experimental Microkinetic Approach of De-NO x by NH 3 on V 2 O 5 /WO 3 /TiO 2 Catalysts. 4. Individual Heats of Adsorption of Adsorbed H 2 O Species on Sulfate-Free and Sulfated TiO 2 Supports

    KAUST Repository

    Giraud, Franç ois; Couble, Julien; Geantet, Christophe; Guilhaume, Nolven; Puzenat, Eric; Gros, Sé bastien; Porcheron, Lynda; Kanniche, Mohamed; Bianchi, Daniel

    2015-01-01

    © 2015 American Chemical Society. The present study is a part of an experimental microkinetic approach of the removal of NOx from coal-fired power plants by reduction with NH3 on V2O5/WO3/TiO2 catalysts (NH3-selective catalytic reduction, NH3-SCR). It is dedicated to the characterization of the heats of adsorption of molecularly adsorbed H2Oads species formed on sulfate-free and sulfated TiO2 supports. Water, which is always present during the NH3-SCR, may be in competition and/or react (formation of NH4+) with the adsorbed NH3 species controlling the coverage of the adsorbed intermediate species of the reaction. Mainly, an original experimental procedure named adsorption equilibrium infrared spectroscopy (AEIR) previously used for the adsorption of NH3 species on the same solids is adapted for the adsorption of H2O. At Ta = 300 K and for PH2 O ≤ 1 kPa, three main H2Oads species are formed (associated with a minor amount of dissociated H2O species) on the two TiO2 solids. The species are identified by the positions of their IR bands in the 3750-3000 cm-1 range. Considering the decreasing order of stability, they are (a) coordinated to strong (L2) and weak (L1) Lewis sites and denoted H2O ads-L2 and H2Oads-L1, respectively, and (b) hydrogen bonded to the H2Oads-L species and on O2-/OH sites of the solids (denoted H2Owads). The three species have a common well-defined δH2O IR band at a position in the range 1640-1610 cm-1 according to the total coverage of the surface. According to the AEIR method, the evolution of the intensity of this IR band during the increase in the adsorption temperature Ta in isobaric condition provides the evolution of the average coverage of the three species and then to their individual heats of adsorption as a function of their coverage. It is shown that there are no significant differences on the two TiO2 solids. In particular, the heat of adsorption of the H2Oads-L2 species varies from ∼114 to 61 kJ/mol at low and high coverages respectively, indicating that it can be present in the experimental conditions of the NH3-SCR. In a forthcoming article, the competitive chemisorptions and reaction between adsorbed H2O and NH3 species are studied and modeled on the TiO2 supports and model and commercial V2O5/WO3/TiO2 catalysts.

  4. Experimental Microkinetic Approach of De-NO x by NH 3 on V 2 O 5 /WO 3 /TiO 2 Catalysts. 4. Individual Heats of Adsorption of Adsorbed H 2 O Species on Sulfate-Free and Sulfated TiO 2 Supports

    KAUST Repository

    Giraud, François

    2015-07-16

    © 2015 American Chemical Society. The present study is a part of an experimental microkinetic approach of the removal of NOx from coal-fired power plants by reduction with NH3 on V2O5/WO3/TiO2 catalysts (NH3-selective catalytic reduction, NH3-SCR). It is dedicated to the characterization of the heats of adsorption of molecularly adsorbed H2Oads species formed on sulfate-free and sulfated TiO2 supports. Water, which is always present during the NH3-SCR, may be in competition and/or react (formation of NH4+) with the adsorbed NH3 species controlling the coverage of the adsorbed intermediate species of the reaction. Mainly, an original experimental procedure named adsorption equilibrium infrared spectroscopy (AEIR) previously used for the adsorption of NH3 species on the same solids is adapted for the adsorption of H2O. At Ta = 300 K and for PH2 O ≤ 1 kPa, three main H2Oads species are formed (associated with a minor amount of dissociated H2O species) on the two TiO2 solids. The species are identified by the positions of their IR bands in the 3750-3000 cm-1 range. Considering the decreasing order of stability, they are (a) coordinated to strong (L2) and weak (L1) Lewis sites and denoted H2O ads-L2 and H2Oads-L1, respectively, and (b) hydrogen bonded to the H2Oads-L species and on O2-/OH sites of the solids (denoted H2Owads). The three species have a common well-defined δH2O IR band at a position in the range 1640-1610 cm-1 according to the total coverage of the surface. According to the AEIR method, the evolution of the intensity of this IR band during the increase in the adsorption temperature Ta in isobaric condition provides the evolution of the average coverage of the three species and then to their individual heats of adsorption as a function of their coverage. It is shown that there are no significant differences on the two TiO2 solids. In particular, the heat of adsorption of the H2Oads-L2 species varies from ∼114 to 61 kJ/mol at low and high coverages respectively, indicating that it can be present in the experimental conditions of the NH3-SCR. In a forthcoming article, the competitive chemisorptions and reaction between adsorbed H2O and NH3 species are studied and modeled on the TiO2 supports and model and commercial V2O5/WO3/TiO2 catalysts.

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

    International Nuclear Information System (INIS)

    Choudhury, Biswajit; Choudhury, Amarjyoti

    2013-01-01

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

  6. Lattice defects in rutile, TiO2

    International Nuclear Information System (INIS)

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

    1991-01-01

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

  7. Fabrication of Li4Ti5O12-TiO2 Nanosheets with Structural Defects as High-Rate and Long-Life Anodes for Lithium-Ion Batteries.

    Science.gov (United States)

    Xu, Hui; Chen, Jian; Li, Yanhuai; Guo, Xinli; Shen, Yuanfang; Wang, Dan; Zhang, Yao; Wang, Zengmei

    2017-06-07

    Development of high-power lithium-ion batteries with high safety and durability has become a key challenge for practical applications of large-scale energy storage devices. Accordingly, we report here on a promising strategy to synthesize a high-rate and long-life Li 4 Ti 5 O 12 -TiO 2 anode material. The novel material exhibits remarkable rate capability and long-term cycle stability. The specific capacities at 20 and 30 C (1 C = 175 mA g -1 ) reach 170.3 and 168.2 mA h g -1 , respectively. Moreover, a capacity of up to 161.3 mA h g -1 is retained after 1000 cycles at 20 C, and the capacity retention ratio reaches up to 94.2%. The extraordinary rate performance of the Li 4 Ti 5 O 12 -TiO 2 composite is attributed to the existence of oxygen vacancies and grain boundaries, significantly enhancing electrical conductivity and lithium insertion/extraction kinetics. Meanwhile, the pseudocapacitive effect is induced owing to the presence of abundant interfaces in the composite, which is beneficial to enhancing specific capacity and rate capability. Additionally, the ultrahigh capacity at low rates, greater than the theoretical value of spinel Li 4 Ti 5 O 12 , may be correlated to the lithium vacancies in 8a sites, increasing the extra docking sites of lithium ions.

  8. Hydrothermal synthesis of 1D TiO2 nanostructures for dye sensitized solar cells

    International Nuclear Information System (INIS)

    Tacchini, I.; Ansón-Casaos, A.; Yu, Youhai; Martínez, M.T.; Lira-Cantu, M.

    2012-01-01

    Highlights: ► Hydrothermal synthesis allows the preparation of different 1D TiO 2 nanostructures easily. ► Nanotubular morphology demonstrates the highest photovoltaic efficiencies in dye sensitized cells (DSCs). ► Morphology at the nanoscale level is as decisive for DSC efficiency as it is TiO 2 crystal structure and surface area. - Abstract: Mono-dimensional titanium oxide nanostructures (multi-walled nanotubes and nanorods) were synthesized by the hydrothermal method and applied to the construction of dye sensitized solar cells (DSCs). First, nanotubes (TiNTs) and nanotubes loaded with titanium oxide nanoparticles (TiNT/NPs) were synthesized with specific surface areas of 253 m 2 /g and 304 m 2 /g, respectively. After that, thermal treatment of the nanotubes at 500 °C resulted in their transformation into the corresponding anatase nanorods (TiNT-Δ and TiNT/NPs-Δ samples). X-ray diffraction and Raman spectroscopy data indicated that titanium oxide in the pristine TiNT and TiNT/NP samples was converted into anatase phase TiO 2 during the heating. Additionally, specific surface areas and water adsorption capacities decreased after the heat treatment due to the sample agglomeration and the collapse of the inner nanotube channels. DSCs were fabricated with the nanotube TiNT and TiNT/NP samples and with the anatase nanorod TiNT-Δ and TiNT/NPs-Δ samples as well. The highest power conversion efficiency of η = 3.12% was obtained for the TiNT sample, despite its lower specific surface compared with the corresponding nanoparticle-loaded sample (TiNT/NP).

  9. STRUKTUR MORFOLOGI, KOMPOSISI KIMIA DAN RESISTANSI LAPISAN TIO2-CU SEBAGAI LAPISAN AKTIF PADA SEL SURYA FOTOELEKTROKIMIA

    Directory of Open Access Journals (Sweden)

    Rita Prasetyowati

    2013-11-01

    Full Text Available Peningkatan efisiensi sel surya titania terus dikembangkan. Salah satunya adalah memodifikasi titania yang berfungsi sebagai lapisan aktif. Lapisan titania dapat disisipi dengan logam Cu. Penyisipan logam Cu pada TiO2 dilakukan melalui pembuatan nanokomposit TiO2-Cu dengan metode sol-gel. Lapisan TiO2-Cu yang terbentuk dikarakterisasi dengan SEM (Scanning Electron Microscopy untuk mengetahui struktur morfologi permukaan, EDX (Energy dispersive X-ray spectroscopy untuk mengetahui komposisi bahan. Sedangkan resistansi lapisan diukur menggunakan Jembatan Wheatstone. Berdasarkan hasil SEM dapat ditunjukkan bahwa struktur morfologi permukaan lapisan TiO2-Cu tidak berbeda secara signifikan dengan lapisan TiO2, yaitu cukup homogen dan memiliki ukuran butir (grain yang hampir sama. Tetapi dari hasil EDX diperoleh bahwa lapisan TiO2-Cu yaitu lapisan TiO2 yang disisipi logam tembaga mengandung  unsur Ti sebanyak 59,8%, unsur O sebanyak 40,02% dan unsur Cu sebanyak 0,19%. Sedangkan lapisan TiO2 saja mengandung unsur Ti sebanyak 54,25% dan unsur O sebanyak 45,75%. Penyisipan logam tembaga pada lapisan titania dapat menurunkan resistansi listrik lapisan. Nilai resistansi lapisan TiO2 adalah 7,714 kilo ohm. Sedangkan nilai resistansi lapisan TiO2-Cu adalah 6,624 kilo ohm.

  10. Fine control of the amount of preferential <001> orientation in DC magnetron sputtered nanocrystalline TiO2 films

    International Nuclear Information System (INIS)

    Stefanov, B; Granqvist, C G; Österlund, L

    2014-01-01

    Different crystal facets of anatase TiO 2 are known to have different chemical reactivity; in particular the {001} facets which truncates the bi-tetrahedral anatase morphology are reported to be more reactive than the usually dominant {101} facets. Anatase TiO 2 thin films were deposited by reactive DC magnetron sputtering in Ar/O 2 atmosphere and were characterized using Rietveld refined grazing incidence X-ray diffraction, atomic force microscopy and UV/Vis spectroscopy. By varying the partial O2 pressure in the deposition chamber, the degree of orientation of the grains in the film could be systematically varied with preferred <001> orientation changing from random upto 39% as determined by March-Dollase method. The orientation of the films is shown to correlate with their reactivity, as measured by photo-degradation of methylene blue in water solutions. The results have implications for fabrication of purposefully chemically reactive thin TiO 2 films prepared by sputtering methods

  11. Synthesis of TiO2 Nanoparticle and its Application to Graphite Composite Electrode for Hydroxylamine Oxidation

    Directory of Open Access Journals (Sweden)

    M. Mazloum-Ardakani

    2013-09-01

    Full Text Available In this work, sol-gel method was used tosynthesize titanium dioxide nanoparticles (TiO2. The TiO2nanoparticles was characterized by Scanning Electron Microscopy (SEM, x-ray diffraction (XRD and BET technique.The TiO2 and coumarin derivative (7-(1,3-dithiolan-2-yl-9, 10-dihydroxy-6H-benzofuro [3,2-c] chromen-6-on were incorporated in a graphite composite electrode. The resulting modified electrode displayed a good electrocatalytic activity for the oxidation of hydroxylamine, which leads to a reduction in its overpotential by more than 520 mV. Differential pulse voltammetry (DPV of hydroxylamine at the modified electrode exhibited a linear dynamic range (between 0.5 and 500.0 µM with a detection limit (3σ of 0.133 μM. The high sensitivity, ease of fabrication and low cost of this modified electrode for the detection of hydroxylamine demonstrate its potential sensing applications.

  12. Spherical anatase TiO2 covered with nanospindles as dual functional scatters for dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Xue, Xiaopan; Tian, Jianhua; Liao, Wenming; Shan, Zhongqiang

    2014-01-01

    Highlights: • Spherical anatase TiO 2 covered with nanospindles (SNS) were employed in DSSCs. • SNS possess the dual functions of light scattering and high dye loading. • SNS were fabricated through a facile hydrothermal treatment of the precursors. • Precursors were synthesized by controlled hydrolysis of TBT after being diluted. • The cells based on SNS-18/P25 photoanode exhibited advanced performance. - Abstract: Spherical anatase TiO 2 covered with nanospindles (SNS) were fabricated through a facile hydrothermal treatment of precursors in the presence of ammonia. The precursors were synthesized by controlling hydrolysis rate of TBT (tetrabutyl titanate) in ethanol. Organic structure directing agents and toxic reagents were avoided in the two–step process. By scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD), it is confirmed that the morphology and structure of the products can be controlled by adjusting hydrothermal treatment conditions. Time dependent trails revealed the growth mechanism of SNS, which indicating that ammonia can not only retard the dissolution of precursors but also make TiO 2 grow selectively along the direction. Furthermore, photocurrent-potential (I-V) curves show that the solar cells fabricated with the SNS collected after 18 h hydrothermal treatment (SNS-18) exhibit the highest solar energy conversion efficiency. The efficiency is improved by 24.5% compared with that of the cells fabricated with pure P25. Based on the UV-Vis spectrum, nitrogen sorption and IPCE analysis, the improved performance can be attributed to the enhanced scattering and increased active sites for dye loading. Therefore, the dual functions of light scattering and many active sites for dye loading make SNS superior candidates for DSSCs

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

    Directory of Open Access Journals (Sweden)

    Gao Dawei

    2018-03-01

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

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

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

    International Nuclear Information System (INIS)

    Dong, Yeshuo; Fei, Xuening; Zhou, Yongzhu

    2017-01-01

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

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

    Science.gov (United States)

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

    2018-05-01

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

  17. Core/Shell Structured TiO2/CdS Electrode to Enhance the Light Stability of Perovskite Solar Cells.

    Science.gov (United States)

    Hwang, Insung; Baek, Minki; Yong, Kijung

    2015-12-23

    In this work, enhanced light stability of perovskite solar cell (PSC) achieved by the introduction of a core/shell-structured CdS/TiO2 electrode and the related mechanism are reported. By a simple solution-based process (SILAR), a uniform CdS shell was coated onto the surface of a TiO2 layer, suppressing the activation of intrinsic trap sites originating from the oxygen vacancies of the TiO2 layer. As a result, the proposed CdS-PSC exhibited highly improved light stability, maintaining nearly 80% of the initial efficiency after 12 h of full sunlight illumination. From the X-ray diffraction analyses, it is suggested that the degradation of the efficiency of PSC during illumination occurs regardless of the decomposition of the perovskite absorber. Considering the light-soaking profiles of the encapsulated cells and the OCVD characteristics, it is likely that the CdS shell had efficiently suppressed the undesirable electron kinetics, such as trapping at the surface defects of the TiO2 and preventing the resultant charge losses by recombination. This study suggests that further complementary research on various effective methods for passivation of the TiO2 layer would be highly meaningful, leading to insight into the fabrication of PSCs stable to UV-light for a long time.

  18. 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

  19. 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

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

    International Nuclear Information System (INIS)

    Selvakumar, M.; Bhat, D. Krishna

    2012-01-01

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

  1. Preparation of Nanoporous TiO2 Electrodes for Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Hsiue-Hsyan Wang

    2011-01-01

    Full Text Available Nano-porous TiO2 thin films have been widely used as the working electrodes in dye-sensitized solar cells (DSSCs. In this work, the phase-pure anatase TiO2 (a-TiO2 and rutile TiO2 (r-TiO2 have been prepared using hydrothermal processes. The investigation of photo-to-electron conversion efficiency of DSSCs fabricated from mixed-TiO2 with a-TiO2 and r-TiO2 ratio of 80 : 20 (A8R2 was performed and compared to that from commercial TiO2 (DP-25. The results showed higher efficiency of DSSC for A8R2 cells with same dependence of cell efficiency on the film thickness for both A8R2 and DP-25 cells. The best efficiency obtained in this work is 5.2% from A8R2 cell with TiO2 film thickness of 12.0 μm. The correlation between the TiO2 films thickness and photoelectron chemical properties of DSSCs fabricated from A8R2 and DP-25 was compared and discussed.

  2. Multi-Layered TiO2 Films towards Enhancement of Escherichia coli Inactivation

    Directory of Open Access Journals (Sweden)

    Sorachon Yoriya

    2016-09-01

    Full Text Available Crystalline TiO2 has shown its great photocatalytic properties in bacterial inactivation. This work presents a design fabrication of low-cost, layered TiO2 films assembled reactors and a study of their performance for a better understanding to elucidate the photocatalytic effect on inactivation of E. coli in water. The ability to reduce the number of bacteria in water samples for the layered TiO2 composing reactors has been investigated as a function of time, while varying the parameters of light sources, initial concentration of bacteria, and ratios of TiO2 film area and volume of water. Herein, the layered TiO2 films have been fabricated on the glass plates by thermal spray coating prior to screen printing, allowing a good adhesion of the films. Surface topology and crystallographic phase of TiO2 for the screen-printed active layer have been characterized, resulting in the ratio of anatase:rutile being 80:20. Under exposure to sunlight and a given condition employed in this study, the optimized film area:water volume of 1:2.62 has shown a significant ability to reduce the E. coli cells in water samples. The ratio of surface area of photocatalytic active base to volume of water medium is believed to play a predominant role facilitating the cells inactivation. The kinetic rate of inactivation and its behavior are also described in terms of adsorption of reaction species at different contact times.

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  4. Study on plasma pre-functionalized PVC film grafted with TiO2/PVP to improve blood compatible and antibacterial properties

    International Nuclear Information System (INIS)

    Suganya, Arjunan; Shanmugavelayutham, Gurusamy; Rodríguez, Carmen Serra

    2017-01-01

    Research into the design of new biopolymers/polymer functionalized with nanoparticles is of tremendous interest to the medical sector, particularly with regard to blood-contacting devices. In this present study, a steady blood compatible and active antibacterial coating was fabricated by the grafting of titanium dioxide (TiO 2 )/polyvinylpyyrolidone (PVP) onto a polyvinyl chloride (PVC) film surface via the direct-current glow discharge plasma method. To enhance the chemical interaction between TiO 2 /PVP and PVC, the surfaces of the PVC films were functionalized by different plasmas (air, argon, and oxygen) before coating. In this study, the plasma parameters were varied, such as treatment time of about 5–20 min for a constant power of 100 W, potential 300 V, and a constant gas pressure of 2 Pa for air, argon, and oxygen gas environment. Then, the different plasma treatments on the PVC films, TiO 2 /PVP were grafted using a simple dip-coating method. In addition, the TiO 2 /PVP-grafted PVC films were characterized by contact angle, attenuated total reflectance Fourier transform infrared spectroscopy, field-emission scanning electron microscope, and x-ray photo electron spectroscopy. Importantly, TiO 2 /PVP is grafted onto the PVC surface due to the plasma-based retained functionality and demonstrates adhesive efficiency, which was observed by XPS. The bio-stability of the TiO 2 /PVP-modified PVC film was evaluated by in vitro platelet activation analysis and protein adsorption analysis. Then, the antibacterial properties were evaluated by the agar diffusion method against Escherichia coli . The result reveals that the grafting of TiO 2 /PVP was slightly higher for the 15 min oxygen plasma-functionalized PVC, which significantly decreases the platelet adhesion and protein adsorption. Moreover, the antibacterial properties of the 15 min oxygen plasma-functionalized PVC with TiO 2 /PVP-grafted film is also greatly improved compared with an air- and argon

  5. Investigation on the Photoelectrocatalytic Activity of Well-Aligned TiO2 Nanotube Arrays

    Directory of Open Access Journals (Sweden)

    Xiaomeng Wu

    2012-01-01

    Full Text Available Well-aligned TiO2 nanotube arrays were fabricated by anodizing Ti foil in viscous F− containing organic electrolytes, and the crystal structure and morphology of the TiO2 nanotube array were characterized and analyzed by XRD, SEM, and TEM, respectively. The photocatalytic activity of the TiO2 nanotube arrays was evaluated in the photocatalytic (PC and photoelectrocatalytic (PEC degradation of methylene blue (MB dye in different supporting solutions. The excellent performance of ca. 97% for color removal was reached after 90 min in the PEC process compared to that of PC process which indicates that a certain external potential bias favors the promotion of the electrode reaction rate on TiO2 nanotube array when it is under illumination. In addition, it is found that PEC process conducted in supporting solutions with low pH and containing Cl− is also beneficial to accelerate the degradation rate of MB.

  6. Heterogeneous activation of H_2O_2 by defect-engineered TiO_2_−_x single crystals for refractory pollutants degradation: A Fenton-like mechanism

    International Nuclear Information System (INIS)

    Zhang, Ai-Yong; Lin, Tan; He, Yuan-Yi; Mou, Yu-Xuan

    2016-01-01

    Highlights: • Facet- and defect-engineered TiO_2 is proposed for water treatment as Fenton-like catalyst. • The =Ti(III) center serves as lattice shuttle for electron transfer in H_2O_2 activation. • TiO_2 is promising due to low cost, high abundance, no toxicity and stable performance. - Abstract: The heterogeneous catalyst plays a key role in Fenton-like reaction for advanced oxidation of refractory pollutants in water treatment. Titanium dioxide (TiO_2) is a typical semiconductor with high industrial importance due to its earth abundance, low cost and no toxicity. In this work, it is found that TiO_2 can heterogeneously activate hydrogen peroxide (H_2O_2, E° = 1.78 eV), a common chemical oxidant, to efficiently generate highly-powerful hydroxyl radical, ·OH (E"0 = 2.80 eV), for advanced water treatment, when its crystal shape, exposed facet and oxygen-stoichiometry are finely tuned. The defect-engineered TiO_2 single crystals exposed by high-energy {0 0 1} facets exhibited an excellent Fenton-like activity and stability for degrading typical refractory organic pollutants such as methyl orange and p-nitrophenol. Its defect-centered Fenton-like superiority is mainly attributed to the crystal oxygen-vacancy, single-crystalline structure and exposed polar {0 0 1} facet. Our findings could provide new chance to utilize TiO_2 for Fenton-like technology, and develop novel heterogeneous catalyst for advanced water treatment.

  7. A Humidity Sensor Based on Nb-doped Nanoporous TiO2 Thin Film

    Directory of Open Access Journals (Sweden)

    Mansoor Anbia

    2011-11-01

    Full Text Available The humidity sensing properties of the sensor fabricated from Nb-doped nanoporous TiO2 by screen-printing on the alumina substrate with Ag-Pd interdigital electrodes have been investigated. The nanoporous thin film has been prepared by sol-gel technique. The product has been characterized by X-ray diffraction and scanning electron microscopy to analyze the structure and its morphology. It is found that the impedance of this sensor changes more than four orders of magnitude in the relative humidity (RH range of 11–95 % at 25 °C. The response and recovery time of the sensor are about 19 and 25 s, respectively, during the RH variation from 11 to 95 %. The sensor shows high humidity sensitivity, rapid response and recovery, prominent stability, good repeatability and narrow hysteresis loop. These results indicate that Nb-doped nanoporous TiO2 thin films have a great potential for humidity sensing applications in room temperature operations.

  8. Preparation of TiO2 hollow fibers using poly(vinylidene fluoride) hollow fiber microfiltration membrane as a template

    International Nuclear Information System (INIS)

    Lu Haiqiang; Zhang Lixiong; Xing Weihong; Wang Huanting; Xu Nanping

    2005-01-01

    TiO 2 hollow fibers were successfully prepared by using poly(vinylidene fluoride) hollow fiber microfiltration membrane as a template. The preparation procedure includes repeated impregnation of the TiO 2 precursor in the pores of the polymeric membrane, and calcination to burn off the template, producing the TiO 2 hollow fibers. The TiO 2 hollow fibers were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). TiO 2 hollow fibers with other structures, such as honeycomb monolith and spring, were also prepared by preshaping the polymeric membranes into the honeycomb structure and spring, respectively. The phase structure of the TiO 2 hollow fibers could be readily adjusted by changing the calcination temperature

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  10. 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

  11. 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

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

    Directory of Open Access Journals (Sweden)

    Pengcheng Yao

    2015-01-01

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

  13. Toward an Active Fabric-Based Air Decontamination System

    National Research Council Canada - National Science Library

    Gaddy, G. A; Bratcher, Matthew S; Mills, G; Huang, S; Slaten, B. L; Debortoli, J

    2004-01-01

    ...) particles that were grafted on cotton fabric and on TiO2 particles that were embedded in glass fabric Modified TiO2 particles were grafted onto cotton fabric and irradiated in the presence of CHCl3...

  14. 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.

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

    Directory of Open Access Journals (Sweden)

    Lingjing Luo

    2014-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Jingfei Chen

    2010-01-01

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

  17. Tailoring the wettability of nanocrystalline TiO 2 films

    Science.gov (United States)

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

    2012-01-01

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

  18. 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

  19. Catalytic Study on TiO2 Photo catalyst Synthesised Via Microemulsion Method on Atrazine

    International Nuclear Information System (INIS)

    Ruslimie, C.A.; Hasmizam Razali; Khairul, W.M.

    2011-01-01

    Titanium dioxide photo catalyst was synthesised by microemulsions method under controlled hydrolysis of titanium butoxide, Ti(O(CH 2 ) 3 )CH 3 . The synthesised TiO 2 photo catalyst was compared with Sigma-commercial TiO 2 by carrying out the investigation on its properties using scanning electron microscopy (SEM), x-ray diffraction (XRD) analysis and thermal gravimetric analysis (TGA). The photo catalytic activities for both photo catalysts were studied for atrazine photodegradation. (author)

  20. Low-temperature atomic layer deposition of TiO2 thin layers for the processing of memristive devices

    International Nuclear Information System (INIS)

    Porro, Samuele; Conti, Daniele; Guastella, Salvatore; Ricciardi, Carlo; Jasmin, Alladin; Pirri, Candido F.; Bejtka, Katarzyna; Perrone, Denis; Chiolerio, Alessandro

    2016-01-01

    Atomic layer deposition (ALD) represents one of the most fundamental techniques capable of satisfying the strict technological requirements imposed by the rapidly evolving electronic components industry. The actual scaling trend is rapidly leading to the fabrication of nanoscaled devices able to overcome limits of the present microelectronic technology, of which the memristor is one of the principal candidates. Since their development in 2008, TiO 2 thin film memristors have been identified as the future technology for resistive random access memories because of their numerous advantages in producing dense, low power-consuming, three-dimensional memory stacks. The typical features of ALD, such as self-limiting and conformal deposition without line-of-sight requirements, are strong assets for fabricating these nanosized devices. This work focuses on the realization of memristors based on low-temperature ALD TiO 2 thin films. In this process, the oxide layer was directly grown on a polymeric photoresist, thus simplifying the fabrication procedure with a direct liftoff patterning instead of a complex dry etching process. The TiO 2 thin films deposited in a temperature range of 120–230 °C were characterized via Raman spectroscopy and x-ray photoelectron spectroscopy, and electrical current–voltage measurements taken in voltage sweep mode were employed to confirm the existence of resistive switching behaviors typical of memristors. These measurements showed that these low-temperature devices exhibit an ON/OFF ratio comparable to that of a high-temperature memristor, thus exhibiting similar performances with respect to memory applications

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

    International Nuclear Information System (INIS)

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

    2017-01-01

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

  2. Sensing and electrical properties of TiO2 nanoparticles

    International Nuclear Information System (INIS)

    Usman, M.

    2011-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Qianzhi Xu

    2015-01-01

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

  4. 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.

  5. Formation of textured microstructure by mist deposition of TiO2 nanoparticles

    International Nuclear Information System (INIS)

    Qin, Gang; Watanabe, Akira

    2013-01-01

    Unique and various textured TiO 2 films have been easily fabricated by mist deposition method on silicon and glass substrates with mild preparation conditions. Two kinds of TiO 2 nanoparticle with different shape, size, and crystal form were used as starting material, which resulted in a simple preparation process under low temperature and ordinary pressure. It was easy to control the thickness, morphology, and roughness of textured TiO 2 film by adjusting the mist deposition conditions such as deposition time, temperature, and the shape and size of nanoparticles. The optical properties of textured TiO 2 films before and after spin coating of Ag nanoparticles were investigated. The angular dependence of the reflectance was obviously reduced by textured TiO 2 surface and such effect was enhanced by Ag nanoparticles coating. A broad plasmon band of Ag grains was observed in the absorption spectrum of the textured Ag nanoparticle-coated TiO 2 film

  6. The influence of metal interlayers on the structural and optical properties of nano-crystalline TiO 2 films

    KAUST Repository

    Yang, Yong

    2012-03-01

    TiO 2-M-TiO 2 (M = W, Co and Ag) multilayer films have been deposited on glass substrates using reactive magnetron sputtering, then annealed in air for 2 h at 500°C. The structure, surface morphology and optical properties of the films have been studied using X-ray diffraction, Raman spectroscopy, atomic force microscopy and UV-vis spectroscopy. The TiO 2-W-TiO 2 and TiO 2-Co-TiO 2 films showed crystalline phases, whereas the TiO 2-Ag-TiO 2 films remained in the amorphous state. The crystallization temperature for the TiO 2-M-TiO 2 films decreased significantly compared with pure TiO 2 film deposited on quartz. Detailed analysis of the Raman spectra suggested that the crystallization of TiO 2-M-TiO 2 films was associated with the large structural deformation imposed by the oxidation of intermediate metal layers. Moreover, the optical band gap of the films narrowed due to the appearance of impurity levels as the metal ions migrated into the TiO 2 matrix. These results indicate that the insertion of intermediate metal layers provides a feasible access to improve the structural and optical properties of anatase TiO 2 films, leading to promising applications in the field of photocatalysis. © 2011 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

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

    2012-02-15

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

  8. Transparent nanostructured Fe-doped TiO2 thin films prepared by ultrasonic assisted spray pyrolysis technique

    Science.gov (United States)

    Rasoulnezhad, Hossein; Hosseinzadeh, Ghader; Ghasemian, Naser; Hosseinzadeh, Reza; Homayoun Keihan, Amir

    2018-05-01

    Nanostructured TiO2 and Fe-doped TiO2 thin films with high transparency were deposited on glass substrate through ultrasonic-assisted spray pyrolysis technique and were used in the visible light photocatalytic degradation of MB dye. The resulting thin films were characterized by scanning electron microscopy (SEM), Raman spectroscopy, photoluminescence spectroscopy, x-ray diffraction (XRD), and UV-visible absorption spectroscopy techniques. Based on Raman spectroscopy results, both of the TiO2 and Fe-doped TiO2 films have anatase crystal structure, however, because of the insertion of Fe in the structure of TiO2 some point defects and oxygen vacancies are formed in the Fe-doped TiO2 thin film. Presence of Fe in the structure of TiO2 decreases the band gap energy of TiO2 and also reduces the electron–hole recombination rate. Decreasing of the electron–hole recombination rate and band gap energy result in the enhancement of the visible light photocatalytic activity of the Fe-doped TiO2 thin film.

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

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  10. Chemical synthesis of CdS onto TiO2 nanorods for quantum dot sensitized solar cells

    Science.gov (United States)

    Pawar, Sachin A.; Patil, Dipali S.; Lokhande, Abhishek C.; Gang, Myeng Gil; Shin, Jae Cheol; Patil, Pramod S.; Kim, Jin Hyeok

    2016-08-01

    A quantum dot sensitized solar cell (QDSSC) is fabricated using hydrothermally grown TiO2 nanorods and successive ionic layer adsorption and reaction (SILAR) deposited CdS. Surface morphology of the TiO2 films coated with different SILAR cycles of CdS is examined by Scanning Electron Microscopy which revealed aggregated CdS QDs coverage grow on increasing onto the TiO2 nanorods with respect to cycle number. Under AM 1.5G illumination, we found the TiO2/CdS QDSSC photoelectrode shows a power conversion efficiency of 1.75%, in an aqueous polysulfide electrolyte with short-circuit photocurrent density of 4.04 mA/cm2 which is higher than that of a bare TiO2 nanorods array.

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

    International Nuclear Information System (INIS)

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

    2016-01-01

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

  12. TiO2 micro-flowers composed of nanotubes and their application to dye-sensitized solar cells

    Science.gov (United States)

    Kim, Woong-Rae; Park, Hun; Choi, Won-Youl

    2014-02-01

    TiO2 micro-flowers were made to bloom on Ti foil by the anodic oxidation of Ti-protruding dots with a cylindrical shape. Arrays of the Ti-protruding dots were prepared by photolithography, which consisted of coating the photoresists, attaching a patterned mask, illuminating with UV light, etching the Ti surface by reactive ion etching (RIE), and stripping the photoresist on the Ti foil. The procedure for the blooming of the TiO2 micro-flowers was analyzed by field emission scanning electron microscopy (FESEM) as the anodizing time was increased. Photoelectrodes of dye-sensitized solar cells (DSCs) were fabricated using TiO2 micro-flowers. Bare TiO2 nanotube arrays were used for reference samples. The short-circuit current ( J sc) and the power conversion efficiency of the DSCs based on the TiO2 micro-flowers were 4.340 mA/cm2 and 1.517%, respectively. These values of DSCs based on TiO2 micro-flowers were higher than those of bare samples. The TiO2 micro-flowers had a larger surface area for dye adsorption compared to bare TiO2 nanotube arrays, resulting in improved J sc characteristics. The structure of the TiO2 micro-flowers allowed it to adsorb dyes very effectively, also demonstrating the potential to achieve higher power conversion efficiency levels for DSCs compared to a bare TiO2 nanotube array structure and the conventional TiO2 nanoparticle structure.

  13. 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.

  14. Glutaraldehyde assisted synthesis of collagen derivative modified Fe3+/TiO2 nanocomposite and their enhanced photocatalytic activity

    International Nuclear Information System (INIS)

    Li, Chongyi; Xue, Feng; Ding, Enyong; He, Xiaoling

    2015-01-01

    Graphical abstract: - Highlights: • Collagen-g-PDMC was successfully designed by grafting DMC monomers onto the collagen backbone. • Fe 3+ /TiO 2 nanospheres highly capable of responding to visible light were successfully prepared. • Collagen-g-PDMC was firmly immobilized onto the Fe 3+ /TiO 2 surface by virtue of glutaraldehyde. • CFT-3 performed the best in the photocatalytic degradation of MO solution under solar irradiation. - Abstract: A unique organic–inorganic hybrid nanocomposite was designed and synthesized by chemically anchoring the cationic collagen-based derivatives onto the surface of Fe 3+ /TiO 2 nanospheres for the significant enhancement in photocatalytic activity under the visible light irradiation. The NMR analysis suggested the successful fabrication of cationic collagen-g-PDMC as grafted materials. In addition, the chemical structures, morphologies and properties of these samples were systematically characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Raman spectrum, ultra violet–visible spectroscopy (UV–vis), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL). And obtained results clearly demonstrated that Fe 3+ ions diffusing into TiO 2 lattice could be responsible for slightly reducing the average diameter of nanospheres to about 125 nm, promoting phase transition from anatase to rutile to some extent and extending the light harvesting range into visible region markedly. Meanwhile, the achievement that collagen-g-PDMC molecules had been covalently immobilized onto the surface of Fe 3+ /TiO 2 nanoparticles was also well supported by the information acquired. Furthermore, the photocatalytic activities of all the as-prepared products were carefully evaluated by adopting photocatalytic decoloration of methyl orange (MO) solution under the solar direct irradiation, and the sample CFT-3 performed the best in

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  16. Production of TiO_2 particles by sol-gel ultrasound assisted for photocatalytic applications

    International Nuclear Information System (INIS)

    Martinez Rojas, Vanessa; Solis Veliz, Jose; Gomez Leon, Monica; Matejova, Lenka; Lopez, Alcides; Cruz, Gerardo J.

    2015-01-01

    Synthesis of TiO_2 particles was made by sol-gel technique assisted of ultrasonic radiation from an alcoholic solution of titanium isopropoxide. Then was subjected to a heat treatment in air at 350 °C for 1 h. X-ray diffraction and transmission electron microscopy confirmed that the size of the crystalline domains is between 10 and 37 nm. Infrared spectroscopy study confirms the presence of -OH groups on the surface of TiO_2. Modification of the morphology and surface area, due to the influence of exposure time to the ultrasonic radiation, is evidenced by studies of SEM and BET respectively. Properties of TiO_2 obtained were studied by monitoring the degradation of solutions of methyl orange in the presence of UV-A radiation. It was observed that larger the ultrasonic radiation exposure during the TiO_2 synthesis larger the constant velocity for the photocatalytic reaction for the methyl orange. (author)

  17. Photoluminescence of heterostructures with GaP1−xNx and GaP1−x−yNxAsy layers grown on GaP and Si substrates by molecular-beam epitaxy

    International Nuclear Information System (INIS)

    Lazarenko, A. A.; Nikitina, E. V.; Sobolev, M. S.; Pirogov, E. V.; Denisov, D. V.; Egorov, A. Yu.

    2015-01-01

    The structural and optical properties of heterostructures containing GaP 1−x N x ternary and GaP 1−x−y N x As y quaternary alloy layers are discussed. The heterostructures are grown by molecular-beam epitaxy on GaP and Si substrates. The structures are studied by the high-resolution X-ray diffraction technique and photoluminescence measurements in a wide temperature range from 10 to 300 K. In the low-temperature photoluminescence spectra of the alloys with a low nitrogen fraction (x < 0.007), two clearly resolved narrow lines attributed to the localized states of nitrogen pairs and the phonon replicas of these lines are observed

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

    International Nuclear Information System (INIS)

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

    2013-01-01

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

  19. The Effects of Doping Copper and Mesoporous Structure on Photocatalytic Properties of TiO2

    Directory of Open Access Journals (Sweden)

    Yang Wang

    2014-01-01

    Full Text Available This paper describes a system for the synthesis of Cu-doped mesoporous TiO2 nanoparticles by a hydrothermal method at relatively low temperatures. The technique used is to dope the as-prepared mesoporous TiO2 system with copper. In this method, the copper species with the form of Cu1+, which was attributed to the reduction effect of dehydroxylation and evidenced by X-ray photoelectron spectroscopy (XPS and X-ray diffraction (XRD, was well dispersed in the optimal concentration 1 wt.% Cu-doped mesoporous TiO2. In this as-prepared mesoporous TiO2 system, original particles with a size of approximately 20 nm are aggregated together to shapes of approximately 1100 nm, which resulted in the porous aggregate structure. More importantly, the enhancement of the photocatalytic activity was discussed as effects due to the formation of stable Cu(I and the mesoporous structure in the Cu-doped mesoporous TiO2. Among them, Cu-doped mesoporous TiO2 shows the highest degradation rate of methyl orange (MO. In addition, the effects of initial solution pH on degradation of MO had also been investigated. As a result, the optimum values of initial solution pH were found to be 3.

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

    International Nuclear Information System (INIS)

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

    2008-01-01

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

  1. 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.

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

    Science.gov (United States)

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

    2017-04-01

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

  3. Enhancement removal of tartrazine dye using HCl-doped polyaniline and TiO2-decorated PANI particles

    Science.gov (United States)

    Elsayed, M. A.; Gobara, Mohamed

    2016-08-01

    HCl-doped polyaniline (HCl-PANI) and titanium dioxide decorated with polyaniline (TiO2-decorated PANI) with different TiO2:PANI ratios were chemically prepared and utilized for the removal of tartrazine (TZ) dye from a synthetic aqueous solution. The mechanism of preparation of the sample suggested that aniline was adsorbed on the TiO2 surface before the polymerization process took place. Samples were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive x-ray spectroscopy and x-ray diffraction. The results showed that HCl-PANI and TiO2-decorated PANI have an amorphous structure. The thermal stability of the prepared samples was characterized using thermo-gravimetric (TG) analysis. HCl-PANI is stable up to 200 °C and the relative weight per cent of PANI in the TiO2-decorated PANI was 20, 25, 40 and 45%. The removal activity of TiO2-decorated PANI via TZ azo dye was investigated under UV light irradiations and compared with HCl-PANI and TiO2 particles. The results indicated the superiority of the TiO2-decorated PANI over pure HCl-PANI and TiO2. However, the excessive PANI percentage tends to form a relatively thick layer, and even aggregates on the surface of TiO2. This hinders the migration of excited electrons from the outer PANI layer to the inner TiO2 particles, which consequently leads to a decrease in the removal efficiency. A possible mechanism for the removal oxidative degradation is also mentioned.

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

    International Nuclear Information System (INIS)

    Tian Hua; Ma Junfeng; Li Kang; Li Jinjun

    2008-01-01

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

  5. PREPARATION AND CHARACTERIZATION OF TiO2-ZEOLITE AND ITS APPLICATION TO DEGRADE TEXTILLE WASTEWATER BY PHOTOCATALYTIC METHOD

    Directory of Open Access Journals (Sweden)

    Yeslia Utubira

    2010-06-01

    Full Text Available The preparation of titanium oxide-zeolite composite (TiO2-zeolite has been done. Preparation was initiated by dispersing oligocation of titanium solution into suspension of natural zeolite. The suspension was stirred and then filtered to separate the solid phase from the filtrate. The solid phase was heated by microwave oven to convert the oligocations into its oxide forms and the resulting material (called as TiO2-zeolite then was used to photodegrade the wastewater of PT.Jogjatex The TiO2-zeolite and unmodified zeolite were characterized using X-ray diffractometry, FT-IR spectro-photometry, X-ray fluorescence (XRF and gas sorption analysis (GSA methods to determine their physicochemical properties. Photocatalytic activity of TiO2-Zeolite was tested by exposing the suspension of TiO2-Zeolite/wastewater by the UV light of 366 nm at room temperature for 15 - 75 minutes. Characterization results exhibited that the formation of TiO2 on internal as well as external surfaces of Zeolite could not be detected  with X-ray diffractometry as well as  FT-IR spectrophotometry, however elemental analysis result with XRF indicated that titanium concentration in zeolite increased due to the inclusion, i.e from 0.26% (w/w in zeolite to 2.80% (w/w in TiO2-zeolite. Characterization result by GSA exhibited the increased of specific surface area from 19.57 m2/g in zeolite to 67.96 m2/g in TiO2-zeolite; total pore volume from 20.64 x 10-3 mL/g in zeolite to 49.561 x 10-3 mL/g in TiO2-Zeolite; pore radius average decreased from 21.10 Å in zeolite to 14.58 Å in TiO2-zeolite. Photocatalytic activity test of TiO2-zeolite on wastewater of PT. Jogjatex showed that UV radiation for 75 minutes on the mixture of TiO2-zeolite and wastewater resulted in the decreased of  COD number up to 57.85%. Meanwhile the sorption study showed that zeolite and TiO2-zeolite could decrease COD number of wastewater up to 43.95% and 57.85%, respectively.   Keywords: TiO2-zeolite

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

    Science.gov (United States)

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

    2014-12-01

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

  7. Effects of TiO2 film thickness on photovoltaic properties of dye-sensitized solar cell and its enhanced performance by graphene combination

    International Nuclear Information System (INIS)

    Zhang, Haiyan; Wang, Wenguang; Liu, Hui; Wang, Rong; Chen, Yiming; Wang, Zhiwei

    2014-01-01

    Graphical abstract: - Highlights: • DSSC based on TiO 2 film with 8 printing layers showed the highest efficiency. • The photoelectric conversion efficiency of the DSSC increased from 5.52% to 6.49% by graphene combination. • A mechanism for the enhanced performance of the DSSC was proposed. - Abstract: Dye-sensitized solar cells based on TiO 2 films with different printing layers (6-10) were fabricated by screen printing method. The prepared samples were characterized by scanning electron microscopy, X-ray diffraction and UV–vis absorption spectroscopy. The effects of thickness on the photoelectric conversion performance of the as-fabricated DSSCs were investigated. An optimum photoelectric conversion efficiency of 5.52% was obtained in a DSSC with 8 printing layers. Furthermore, after a moderate amount of graphene was combined with TiO 2 , the photoelectric conversion efficiency of the DSSC based on graphene/TiO 2 composite film rose from 5.52% to 6.49%, with an increase of η by 17.6%. The results indicated that graphene not only enhances the transport of electrons from the film to the fluorine doped tin oxide substrates and reduces the charge recombination rate, but also reduces the electrolyte–electrode interfacial resistance, clearly increasing the photoelectric conversion efficiency

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

    Directory of Open Access Journals (Sweden)

    V. A. Mu’izayanti

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

  9. One-step preparation and photocatalytic performance of vanadium doped TiO2 coatings

    International Nuclear Information System (INIS)

    Vasilić, R.; Stojadinović, S.; Radić, N.; Stefanov, P.; Dohčević-Mitrović, Z.; Grbić, B.

    2015-01-01

    In this paper, we have investigated one-step preparation of vanadium doped TiO 2 coatings formed by plasma electrolytic oxidation (PEO) of titanium in electrolyte containing 10 g/L Na 3 PO 4 ·12H 2 O + 0.5 g/L NH 4 VO 3 . The morphology, phase structure, and elemental composition of the formed coatings were characterized by atomic force microscopy (AFM), x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS) techniques. Ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS) was employed to evaluate the band gap energy of obtained coatings. Vanadium doped TiO 2 coatings are partly crystallized and mainly composed of anatase phase TiO 2 , with up to about 2 wt% of vanadium present in the surface layer of the oxide. The valence band photoelectron spectra and UV–Vis DRS showed that vanadium doped TiO 2 coatings exhibit notable red shift with respect to the pure TiO 2 coatings. The photocatalytic activity was evaluated by monitoring the degradation of methyl orange under simulated sunlight conditions. Photocatalytic activity of vanadium doped TiO 2 coatings increases with PEO time. Prolonged PEO times result in higher roughness of obtained coatings, thus increasing surface area available for methyl orange degradation. Vanadium doped TiO 2 coatings obtained after 180 s of PEO time exhibit the best photocatalytic activity and about 67% of methyl orange is degraded after 12 h of irradiation under simulated sunlight. - Highlights: • One-step preparation of V-doped TiO 2 coatings in 10 g/L Na 3 PO 4 ·12H 2 O + 0.5 g/L NH 4 VO 3 . • Properties of obtained coatings strongly depend on microdischarge characteristics. • Band gap of V-doped TiO 2 coatings is shifted towards red side of the spectrum. • V-doped TiO 2 coatings have better photocatalytic activity than pure TiO 2 . • After 12 h of simulated sunlight irradiation, 67% of methyl orange was decomposed

  10. Hydrogenated TiO2 nanotube photonic crystals for enhanced photoelectrochemical water splitting.

    Science.gov (United States)

    Meng, Ming; Zhou, Sihua; Yang, Lun; Gan, Zhixing; Liu, Kuili; Tian, Fengshou; Zhu, Yu; Li, ChunYang; Liu, Weifeng; Yuan, Honglei; Zhang, Yan

    2018-04-02

    We report the design, fabrication and characterization of novel TiO 2 nanotube photonic crystals with a crystalline core/disordered shell structure as well as substantial oxygen vacancies for photoelectrochemical (PEC) water splitting. The novel TiO 2 nanotube photonic crystals are fabricated by annealing of anodized TiO 2 nanotube photonic crystals in hydrogen atmosphere at various temperatures. The optimized novel TiO 2 nanotube photonic crystals produce a maximal photocurrent density of 2.2 mA cm -2 at 0.22 V versus Ag/AgCl, which is two times higher that of the TiO 2 nanotube photonic crystals annealed in air. Such significant PEC performance improvement can be ascribed to synergistic effects of the disordered surface layer and oxygen vacancies. The reduced band gap owing to the disordered surface layer and localized states induced by oxygen vacancies can enhance the efficient utilization of visible light. In addition, the disordered surface layer and substantial oxygen vacancies can promote the efficiency for separation and transport of the photogenerated carriers. This work may open up new opportunities for the design and construction of the high efficient and low-cost PEC water splitting system.

  11. Preparation and photoelectrocatalytic performance of N-doped TiO2/NaY zeolite membrane composite electrode material.

    Science.gov (United States)

    Cheng, Zhi-Lin; Han, Shuai

    2016-01-01

    A novel composite electrode material based on a N-doped TiO2-loaded NaY zeolite membrane (N-doped TiO2/NaY zeolite membrane) for photoelectrocatalysis was presented. X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible (UV-vis) and X-ray photoelectron spectroscopy (XPS) characterization techniques were used to analyze the structure of the N-doped TiO2/NaY zeolite membrane. The XRD and SEM results verified that the N-doped TiO2 nanoparticles with the size of ca. 20 nm have been successfully loaded on the porous stainless steel-supported NaY zeolite membrane. The UV-vis result showed that the N-doped TiO2/NaY zeolite membrane exhibited a more obvious red-shift than that of N-TiO2 nanoparticles. The XPS characterization revealed that the doping of N element into TiO2 was successfully achieved. The photoelectrocatalysis performance of the N-doped TiO2/NaY zeolite membrane composite electrode material was evaluated by phenol removal and also the effects of reaction conditions on the catalytic performance were investigated. Owing to exhibiting an excellent catalytic activity and good recycling stability, the N-doped TiO2/NaY zeolite membrane composite electrode material was of promising application for photoelectrocatalysis in wastewater treatment.

  12. Karakteristik Pasta TiO2 Suhu Rendah untuk Aplikasi Dye Sensitized Solar Cell (DSSC

    Directory of Open Access Journals (Sweden)

    Mariya Al Qibtiya

    2016-06-01

    Full Text Available Pada tulisan ini, diuraikan karakteristik pasta TiO2 suhu rendah untuk aplikasi sel surya berbasis dye-sensitized yang dipreparasi dengan penambahan serbuk TiO2 reflektor. Penambahan TiO2 reflektor sebagai light scattering layer pada pasta dilakukan untuk melihat pengaruhnya terhadap karakteristik listrik sel surya yang dihasilkan. Preparasi pasta dilakukan menggunakan bahan komersial yaitu pasta T-Nanooxide D-L (Solaronix dan serbuk pasta WER2-O (Dyesiol sebagai bahan reflector. Bahan tersebut dianalisis struktur kristalnya. Hasil karakterisasi X-Ray Diffraction (XRD menunjukan bahwa bahan TiO2 serbuk yang digunakan adalah nanokristal dengan struktur kristal anatase. Pasta ini dideposisi di atas permukaan plastik dan kaca konduktif (ITO-PET dan FTO dengan metode doctor blade printing. Proses sintering lapisan TiO2 dilakukan pada suhu rendah yaitu 120 ˚C selama 4 jam. Morfologi permukaan lapisan TiO2 dianalisa menggunakan Scanning Electron Microscopy (SEM. Lapisan TiO2 yang terbentuk diaplikasikan pada DSSC sebagai fotoelektroda. Pewarnaan dengan larutan N-719 (Ruthenium Complex, lapisan elektroda kerja platina dan larutan elektrolit iodine. Karakteristik kurva I-V dengan ukuran sel daerah aktif 1 cm2 diukur menggunakan Sun Simulator AM1,5 dengan sumber cahaya Xenon dan intensitas 50 mW/cm2. Hasil pengukuran menunjukkan penambahan serbuk TiO2 reflektor dapat meningkatkan unjuk kerja sel surya fleksibel yang dihasilkan. Efisiensi terbaik DSSC yang dihasilkan adalah 0,166% untuk substrat plastik dan 0,167% untuk substrat kaca.

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

    Science.gov (United States)

    Zakrzewska, K; Radecka, M

    2017-12-01

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

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

    Science.gov (United States)

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

    2011-10-01

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

  15. Preparation and characterization of a novel PVDF ultrafiltration membrane by blending with TiO_2-HNTs nanocomposites

    International Nuclear Information System (INIS)

    Zeng, Guangyong; He, Yi; Yu, Zongxue; Zhan, Yingqing; Ma, Lan; Zhang, Lei

    2016-01-01

    Highlights: • A novel TiO_2-HNTs/PVDF ultrafiltration membrane was prepared. • TiO_2 dispersed well in membrane matrix by loading on the surface of HNTs. • The hydrophilicity of membrane was improved with the addition of TiO_2-HNTs. • TiO_2-HNTs/PVDF membranes showed good antifouling performance. - Abstract: Novel polyvinylidene fluoride (PVDF) ultrafiltration membranes were prepared by blending with different contents of titanium dioxide-halloysite nanotubes (TiO_2-HNTs) composites into the PVDF matrix. The effects of TiO_2-HNTs content on the membrane performances, such as hydrophilicity, rejection ratio and antifouling properties were investigated in detail. X-ray diffraction (XRD), thermo-gravimetric analyzer (TGA) and scanning electron microscope (SEM) analyses showed that TiO_2 was loaded on the surface of HNTs successfully and homogeneously by sol-gel method. The morphologies and microstructure of the membranes were characterized by SEM and atomic force microscopy (AFM). The contact angle (CA) tests indicated that the hydrophilicity of membranes was significantly increased with the addition of TiO_2-HNTs. The pure water flux of 3%TiO_2-HNTs/PVDF was increased by 264.8% and 35.6%, respectively, compared with pure PVDF membrane and 3%TiO_2/PVDF membrane, although the rejection of bovine serum albumin (BSA) was slightly decreased. More importantly, TiO_2-HNTs/PVDF membrane exhibited an excellent anti-fouling performance, which was attributed to the hydrophobic contaminants being resisted by hydrophilic nanoparticles. It can be expected that this work may provide some references to solve the dispersion of nanoparticle in the membrane and improve the anti-fouling performance of membrane in the field of wastewater treatment.

  16. Photoetching of Immobilized TiO2-ENR50-PVC Composite for Improved Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    M. A. Nawi

    2012-01-01

    Full Text Available Commercially acquired TiO2 photocatalyst (99% anatase powder was mixed with epoxidized natural rubber-50 (ENR50/polyvinyl chloride (PVC blend by ultrasonication and immobilized onto glass plates as TiO2-ENR50-PVC composite via a dip-coating method. Photoetching of the immobilized TiO2-ENR50-PVC composite was investigated under the irradiation of a 45 W compact fluorescent lamp and characterized by chemical oxygen demand (COD analysis, scanning electron microscopy-energy dispersive X-ray (SEM-EDX spectrometry, thermogravimetry analysis (TGA, and fourier transform infrared (FTIR spectroscopy. The BET surface area of the photoetched TiO2 composite was observed to be larger than the original TiO2 powder due to the systematic removal of ENR50 while PVC was retained within the composite. It also exhibited better photocatalytic efficiency than the TiO2 powder in a slurry mode and was highly reproducible and reusable. More than 98% of MB removal was consistently achieved for 10 repeated runs of the photo-etched photocatalyst system. About 93% of the 20 mg L−1 MB was mineralized over a period of 480 min. The presence of SO42−, NO3−, and Cl− anions was detected in the mineralized solution where the solution pH was reduced from 7 to 4.

  17. Enhanced oxidation of naphthalene using plasma activation of TiO2/diatomite catalyst.

    Science.gov (United States)

    Wu, Zuliang; Zhu, Zhoubin; Hao, Xiaodong; Zhou, Weili; Han, Jingyi; Tang, Xiujuan; Yao, Shuiliang; Zhang, Xuming

    2018-04-05

    Non-thermal plasma technology has great potential in reducing polycyclic aromatic hydrocarbons (PAHs) emission. But in plasma-alone process, various undesired by-products are produced, which causes secondary pollutions. Here, a dielectric barrier discharge (DBD) reactor has been developed for the oxidation of naphthalene over a TiO 2 /diatomite catalyst at low temperature. In comparison to plasma-alone process, the combination of plasma and TiO 2 /diatomite catalyst significantly enhanced naphthalene conversion (up to 40%) and CO x selectivity (up to 92%), and substantially reduced the formation of aerosol (up to 90%) and secondary volatile organic compounds (up to near 100%). The mechanistic study suggested that the presence of the TiO 2 /diatomite catalyst intensified the electron energy in the DBD. Meantime, the energized electrons generated in the discharge activated TiO 2 , while the presence of ozone enhanced the activity of the TiO 2 /diatomite catalyst. This plasma-catalyst interaction led to the synergetic effect resulting from the combination of plasma and TiO 2 /diatomite catalyst, consequently enhanced the oxidation of naphthalene. Importantly, we have demonstrated the effectiveness of plasma to activate the photocatalyst for the deep oxidation of PAH without external heating, which is potentially valuable in the development of cost-effective gas cleaning process for the removal of PAHs in vehicle applications during cold start conditions. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Enhancement of tributyltin degradation under natural light by N-doped TiO2 photocatalyst

    International Nuclear Information System (INIS)

    Bangkedphol, S.; Keenan, H.E.; Davidson, C.M.; Sakultantimetha, A.; Sirisaksoontorn, W.; Songsasen, A.

    2010-01-01

    Photo-degradation of tributyltin (TBT) has been enhanced by TiO 2 nanoparticles doped with nitrogen (N-doped TiO 2 ). The N-doped catalyst was prepared by a sol-gel reaction of titanium (IV) tetraisopropoxide with 25% ammonia solution and calcined at various temperatures from 300 to 600 deg. C. X-ray diffraction results showed that N-doped TiO 2 remained amorphous at 300 deg. C. At 400 deg. C the anatase phase occurred then transformed to the rutile phase at 600 deg. C. The crystallite size calculated from Scherrer's equation was in the range of 16-51 nm which depended on the calcination temperature. N-doped TiO 2 calcined at 400 deg. C which contained 0.054% nitrogen, demonstrated the highest photocatalytic degradation of TBT at 28% in 3 h under natural light when compared with undoped TiO 2 and commercial photocatalyst, P25-TiO 2 which gave 14.8 and 18% conversion, respectively.

  19. Photocatalytic Degradation of Methylene Blue Using TiO2 Impregnated Diatomite

    Directory of Open Access Journals (Sweden)

    Ranfang Zuo

    2014-01-01

    Full Text Available Nano-TiO2 showed a good catalytic activity, but it is easy to agglomerate, resulting in the reduction or even complete loss of photocatalytic activity. The dispersion of TiO2 particles on porous materials was a potential solution to this problem. Diatomite has high specific surface and absorbability because of its particular shell structure. Thus, TiO2/diatomite composite, prepared by loading TiO2 on the surface of diatomite, was a good photocatalyst, through absorbing organic compounds with diatomite and degrading them with TiO2. Scanning electron microscopy (SEM, energy dispersive spectrum (EDS, X-ray diffraction (XRD, chemical analysis, and Fourier transform infrared spectrometry (FTIR indicated that TiO2 was impregnated well on the surface of diatomite. Furthermore, TiO2/diatomite was more active than nano-TiO2 for the degradation of methylene blue (MB in solution. MB at concentrations of 15 and 35 ppm can be completely degraded in 20 and 40 min, respectively.

  20. 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.

  1. Biocompatibility and Surface Properties of TiO2 Thin Films Deposited by DC Magnetron Sputtering

    Science.gov (United States)

    López-Huerta, Francisco; Cervantes, Blanca; González, Octavio; Hernández-Torres, Julián; García-González, Leandro; Vega, Rosario; Herrera-May, Agustín L.; Soto, Enrique

    2014-01-01

    We present the study of the biocompatibility and surface properties of titanium dioxide (TiO2) thin films deposited by direct current magnetron sputtering. These films are deposited on a quartz substrate at room temperature and annealed with different temperatures (100, 300, 500, 800 and 1100 °C). The biocompatibility of the TiO2 thin films is analyzed using primary cultures of dorsal root ganglion (DRG) of Wistar rats, whose neurons are incubated on the TiO2 thin films and on a control substrate during 18 to 24 h. These neurons are activated by electrical stimuli and its ionic currents and action potential activity recorded. Through X-ray diffraction (XRD), the surface of TiO2 thin films showed a good quality, homogeneity and roughness. The XRD results showed the anatase to rutile phase transition in TiO2 thin films at temperatures between 500 and 1100 °C. This phase had a grain size from 15 to 38 nm, which allowed a suitable structural and crystal phase stability of the TiO2 thin films for low and high temperature. The biocompatibility experiments of these films indicated that they were appropriated for culture of living neurons which displayed normal electrical behavior. PMID:28788667

  2. Photocatalytic properties of nanocrystalline TiO2 thin film with Ag additions

    International Nuclear Information System (INIS)

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

    2006-01-01

    In the present study, nanocrystalline TiO 2 /Ag composite thin films were prepared by a sol-gel spin coating technique. While, by introducing polystyrene (PS) microspheres, porous TiO 2 /Ag films were obtained after calcining at a temperature of 500 o C. The as-prepared TiO 2 and TiO 2 /Ag thin films were characterized by X-ray diffractometry, and scanning electron microscopy to reveal the structural and morphological differences. In addition, the photocatalytic properties of these films were investigated by degrading methylene blue under UV irradiation. After 500 o C calcination, the microstructure of PS-TiO 2 film without Ag addition exhibited a sponge-like microstructure while significant sintering effect was noticed with Ag additions and the films exhibited a porous microstructure. Meanwhile, coalescence of nanocrystalline anatase-phase TiO 2 can be observed with respect to the sharpening of XRD diffraction peaks. The photodegradation of porous TiO 2 doped with 1 mol% Ag exhibited the best photocatalytic efficiency where 72% methylene blue can be decomposed after UV exposure for 12 h

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

    Science.gov (United States)

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

    2013-11-01

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

  4. Production and Characterization of (004) Oriented Single Anatase TiO2 Films

    Science.gov (United States)

    Atay, Ferhunde; Akyuz, Idris; Cergel, Muge Soyleyici; Erdogan, Banu

    2018-02-01

    Highly (004) oriented anatase TiO2 films have been successfully obtained by an inexpensive ultrasonic spray pyrolysis technique at low substrate temperatures and without additional annealing. X-ray diffraction analysis, ultraviolet-visible spectroscopy and field emission scanning electron microscopy were used to analyze the structural, optical and surface properties of the films. By using the less reported TiCl4 solution, the optical band gap values falling into the visible region (between 2.70 eV and 2.92 eV) have been obtained for all films. Spectroscopic ellipsometry technique has been used to determine the dispersive refractive index and extinction coefficient of TiO2 films. Possible electrical conduction mechanisms in TiO2 films have been examined using temperature dependent conductivity measurements in the temperature range of 78-300 K. At room temperature, electrical resistivity values of TiO2 films change between 1.68 × 104 Ω cm and 5.88 × 104 Ω cm. Considering the analyzed parameters with respect to substrate temperature, this work refers to the properties of anatase TiO2 films that are strongly correlated to the growth direction, namely (004). As a result, (004) oriented anatase TiO2 films with appropriate optical band gap values are promising materials for technological applications, especially for photocatalysts.

  5. Origin of visible-light sensitivity in N-doped TiO2 films

    International Nuclear Information System (INIS)

    Nakano, Yoshitaka; Morikawa, Takeshi; Ohwaki, Takeshi; Taga, Yasunori

    2007-01-01

    We report on visible-light sensitivity in N-doped TiO 2 (TiO 2 :N) films that were deposited on n + -GaN/Al 2 O 3 substrates by reactive magnetron sputtering and subsequently crystallized by annealing at 550 deg. C in flowing N 2 gas. The N-doping concentration was ∼8.8%, as determined by X-ray photoelectron spectroscopy measurements. From transmission electron microscopic observations and optical absorption measurements, yellow-colored TiO 2 :N samples showed an enhanced granular structure and strong absorption in the visible-light region. Photoelectron spectroscopy in air measurements showed a noticeable decrease in ionization energy of TiO 2 by the N doping. Deep-level optical spectroscopy measurements revealed two characteristic deep levels located at ∼1.18 and ∼2.48 eV below the conduction band. The 1.18 eV level is probably attributable to the O vacancy state and can be active as an efficient generation-recombination center. The pronounced 2.48 eV band is newly introduced by the N doping and contributes to band-gap narrowing of TiO 2 by mixing with the O 2p valence band. Therefore, this localized intraband is probably one origin of visible-light sensitivity in TiO 2 :N

  6. 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).

  7. The double peaks and symmetric path phenomena in the catalytic activity of Pd/Al2O3-TiO2 catalysts with different TiO2 contents

    Science.gov (United States)

    Zhang, Shen; Guo, Yuyu; Li, Xingying; Wu, Xu; Li, Zhe

    2018-06-01

    Physicochemical properties of Pd/Al2O3-TiO2 catalysts with different amounts of TiO2 contents were investigated by XRD, nitrogen adsorption-desorption, FTIR, NH3-TPD, H2-TPR and XPS techniques. Catalysts of different compositions were tested in the ethanol oxidation reaction to study the effects of TiO2 contents. Double peaks and symmetric path phenomena were observed at certain temperatures with the increase in TiO2 contents. The symmetric peak phenomena and the diverse activity fluctuations have been ascribed to the controlling factors such as temperature and compositions. With the increase in TiO2 content, the surface area, adsorbed oxygen contents and surface acid quantity decreased gradually. The large surface area and adsorbed oxygen contents were conducive to the performance, while increased acid amounts were not beneficial for ethanol oxidation. At 150 and 175 °C, Pd/AT(X1

  8. New insights into the origin of visible-light photocatalytic activity in Se-modified anatase TiO2 from screened coulomb hybrid DFT calculations

    KAUST Repository

    Harb, Moussab

    2013-01-01

    ), TiO(2-x)Sex (containing Se2- species), and TiO(2-x)Se2x (containing Se2 2- species) reveal significant enhanced visible-light optical absorption spectra with new absorption features appearing at 500, 600, and 690 nm, respectively. Our calculated

  9. Photocatalytic methane decomposition over vertically aligned transparent TiO2 nanotube arrays

    DEFF Research Database (Denmark)

    In, Su-il; Nielsen, Morten Godtfred; Vesborg, Peter Christian Kjærgaard

    2011-01-01

    Vertically aligned transparent TiO2 nanotube arrays grown by the one-step anodic oxidation technique (on non-conductive supports such as Pyrex) and their photocatalytic performance for methane decomposition in a single-pass micro-fabricated reactor under UV light....

  10. 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%.

  11. 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)

  12. The effect of erbium on the adsorption and photodegradation of orange I in aqueous Er3+-TiO2 suspension

    International Nuclear Information System (INIS)

    Liang Chunhua; Hou Meifang; Zhou Shungui; Li Fangbai; Liu Chengshuai; Liu Tongxu; Gao Yuanxue; Wang Xugang; Lue Jialong

    2006-01-01

    Pure TiO 2 and erbium ion-doped TiO 2 (Er 3+ -TiO 2 ) catalysts prepared by the sol-gel method were characterized by means of XRD and diffusive reflectance spectra (DRS). The XRD results showed that erbium ion doping could enhance the thermal stability of TiO 2 and inhibit the increase of the crystallite size, and the DRS results showed that the optical absorption edge slightly shifted to red direction owing to erbium ion doping and the Er 3+ -TiO 2 catalysts had three typical absorption peaks located at 490, 523 and 654 nm owing to the transition of 4f electron from 4 I 15/2 to 4 F 7/2 , 2 H 11/2 and 4 F 9/2 . With a purpose of azo dyes degradation, orange I was used as a model chemical. And the adsorption isotherm, degradation and mineralization of orange I were investigated in aqueous suspension of pure TiO 2 or Er 3+ -TiO 2 catalysts. The results showed that Er 3+ -TiO 2 catalysts had higher adsorption equilibrium constants and better adsorption capacity than pure TiO 2 . The adsorption equilibrium constants (K a ) of Er 3+ -TiO 2 catalysts were about twice of that of pure TiO 2 . The maximum adsorption capacity (Q max ) of 2.0% Er 3+ -TiO 2 catalyst was 13.08 x 10 -5 mol/g, which was much higher than that of pure TiO 2 with 9.03 x 10 -5 mol/g. Among Er 3+ -TiO 2 catalysts, 2.0% Er 3+ -TiO 2 catalyst achieved the highest Q max and K a values. The kinetics of the orange I degradation using different Er 3+ -TiO 2 catalysts were also studied. The results demonstrated that the degradation and mineralization of orange I under both UV radiation and visible light were more efficient with Er 3+ -TiO 2 catalyst than with pure TiO 2 , and an optimal dosage of erbium ion at 1.5% achieved the highest degradation rate. The higher photoactivity under visible light might be attributable to the transitions of 4f electrons of Er 3+ and red shifts of the optical absorption edge of TiO 2 by erbium ion doping

  13. Guided proliferation and bone-forming functionality on highly ordered large diameter TiO2 nanotube arrays

    International Nuclear Information System (INIS)

    Zhang, Ruopeng; Wu, Hongliu; Ni, Jiahua; Zhao, Changli; Chen, Yifan; Zheng, Chengjunyi; Zhang, Xiaonong

    2015-01-01

    The significantly enhanced osteoblast adhesion, proliferation and alkaline phosphatase (ALP) activity were observed on TiO 2 nanotube surface in recent studies in which the scale of nanotube diameter was restricted under 100 nm. In this paper, a series of highly ordered TiO 2 nanotube arrays with larger diameters ranging from 150 nm to 470 nm were fabricated via high voltage anodization. The behaviors of MC3T3-E1 cells in response to the diameter-controlled TiO 2 nanotubes were investigated. A contrast between the trend of proliferation and the trend of cell elongation was observed. The highest cell elongation (nearly 10:1) and the lowest cell number were observed on the TiO 2 nanotube arrays with 150 nm diameter. While, the lowest cell elongation and highest cell number were achieved on the TiO 2 nanotube arrays with 470 nm diameter. Furthermore, the ALP activity peaked on the 150 nm diameter TiO 2 nanotube arrays and decreased dramatically with the increase of nanotube diameter. Thus a narrow range of diameter (100–200 nm) that could induce the greatest bone-forming activity is determined. It is expected that more delicate design of orthopedic implant with regional abduction of cell proliferation or bone forming could be achieved by controlling the diameter of TiO 2 nanotubes. - Highlights: • Improved anodization methods leading to more ordered large diameter TiO 2 nanotubes • Significantly enhanced ALP activity was observed on 150 nm diameter TiO 2 nanotubes. • The highest cell density was observed on 470 nm diameter TiO 2 nanotube arrays. • Similar cell response was observed on the amorphous and anatase phased nanotube surface

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

    Directory of Open Access Journals (Sweden)

    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

  15. 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.

  16. Photoluminescence studies on Eu doped TiO2 nanoparticles

    International Nuclear Information System (INIS)

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

    2009-01-01

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

  17. Research Update: Doping ZnO and TiO2 for solar cells

    Directory of Open Access Journals (Sweden)

    Robert L. Z. Hoye

    2013-12-01

    Full Text Available ZnO and TiO2 are two of the most commonly used n-type metal oxide semiconductors in new generation solar cells due to their abundance, low-cost, and stability. ZnO and TiO2 can be used as active layers, photoanodes, buffer layers, transparent conducting oxides, hole-blocking layers, and intermediate layers. Doping is essential to tailor the materials properties for each application. The dopants used and their impact in solar cells are reviewed. In addition, the advantages, disadvantages, and commercial potential of the various fabrication methods of these oxides are presented.

  18. 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...

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

    Science.gov (United States)

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

    2017-12-01

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

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

    Science.gov (United States)

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

    2017-01-01

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

  1. Synthesis and enhanced photoelectrocatalytic activity of p–n junction Co3O4/TiO2 nanotube arrays

    International Nuclear Information System (INIS)

    Dai Gaopeng; Liu Suqin; Liang Ying; Luo Tianxiong

    2013-01-01

    Highlights: ► Co 3 O 4 /TiO 2 nanotube arrays (NTs) were prepared by an impregnating–deposition–decompostion method treatment. ► Co 3 O 4 /TiO 2 NTs exhibit high photoelectrocatalytic (PEC) activity. ► The high PEC activity was attribute to the formation of p–n junction between Co 3 O 4 and TiO 2 . - Abstract: Co 3 O 4 /TiO 2 nanotube arrays (NTs) were prepared by depositing Co 3 O 4 nanoparticles (NPs) on the tube wall of the self-organized TiO 2 NTs using an impregnating–deposition–decompostion method. The prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV–vis absorption spectroscopy. The photoelectrocatalytic (PEC) activity is evaluated by degradation of methyl orange (MO) aqueous solution. The prepared Co 3 O 4 /TiO 2 NTs exhibit much higher PEC activity than TiO 2 NTs due to the p–n junction formed between Co 3 O 4 and TiO 2 .

  2. A fast-reliable methodology to estimate the concentration of rutile or anatase phases of TiO2

    Directory of Open Access Journals (Sweden)

    A. R. Zanatta

    2017-07-01

    Full Text Available Titanium-dioxide (TiO2 is a low-cost, chemically inert material that became the basis of many modern applications ranging from, for example, cosmetics to photovoltaics. TiO2 exists in three different crystal phases − Rutile, Anatase and, less commonly, Brookite − and, in most of the cases, the presence or relative amount of these phases are essential to decide the TiO2 final application and its related efficiency. Traditionally, X-ray diffraction has been chosen to study TiO2 and provides both the phases identification and the Rutile-to-Anatase ratio. Similar information can be achieved from Raman scattering spectroscopy that, additionally, is versatile and involves rather simple instrumentation. Motivated by these aspects this work took into account various TiO2 Rutile+Anatase powder mixtures and their corresponding Raman spectra. Essentially, the method described here was based upon the fact that the Rutile and Anatase crystal phases have distinctive phonon features, and therefore, the composition of the TiO2 mixtures can be readily assessed from their Raman spectra. The experimental results clearly demonstrate the suitability of Raman spectroscopy in estimating the concentration of Rutile or Anatase in TiO2 and is expected to influence the study of TiO2-related thin films, interfaces, systems with reduced dimensions, and devices like photocatalytic and solar cells.

  3. Efficient and stable CH3NH3PbI3-x(SCN)x planar perovskite solar cells fabricated in ambient air with low-temperature process

    Science.gov (United States)

    Zhang, Zongbao; Zhou, Yang; Cai, Yangyang; Liu, Hui; Qin, Qiqi; Lu, Xubing; Gao, Xingsen; Shui, Lingling; Wu, Sujuan; Liu, Jun-Ming

    2018-02-01

    Planar perovskite solar cells (PSCs) based on CH3NH3PbI3-x(SCN)x (SCN: thiocyanate) active layer and low-temperature processed TiO2 films are fabricated by a sequential two-step method in ambient air. Here, alkali thiocyanates (NaSCN, KSCN) are added into Pb(SCN)2 precursor to improve the microstructure of CH3NH3PbI3-x(SCN)x perovskite layers and performance of the as-prepared PSCs. At the optimum concentrations of alkali thiocyanates as additives, the as-prepared NaSCN-modified and KSCN-modified PSCs demonstrate the efficiencies of 16.59% and 15.63% respectively, being much higher than 12.73% of the reference PSCs without additives. This improvement is primarily ascribed to the enhanced electron transport, reduced recombination rates and much improved microstructures with large grain size and low defect density at grain boundaries. Importantly, it is revealed that the modified PSCs at the optimized concentrations of alkali thiocyanates additives exhibit remarkably improved stability than the reference PSCs against humid circumstance, and a continuous exposure to humid air without encapsulation over 45 days only records about 5% degradation of the efficiency. These findings provide a facile approach to fabricate efficient and stable PSCs by low processing temperature in ambient air, both of which are highly preferred for future practical applications of PSCs.

  4. Enhanced photochemical catalysis of TiO2 inverse opals by modification with ZnO or Fe2O3 using ALD and the hydrothermal method

    Science.gov (United States)

    Liu, Jiatong; Sun, Cuifeng; Fu, Ming; Long, Jie; He, Dawei; Wang, Yongsheng

    2018-02-01

    The development of porous materials exhibiting photon regulation abilities for improved photoelectrochemical catalysis performance is always one of the important goals of solar energy harvesting. In this study, methods to improve the photocatalytic activity of TiO2 inverse opals were discussed. TiO2 inverse opals were prepared by atomic layer deposition (ALD) using colloidal crystal templates. In addition, TiO2 inverse opal heterostructures were fabricated using colloidal heterocrystals by repeated vertical deposition using different colloidal spheres. The hydrothermal method and ALD were used to prepare ZnO- or Fe2O3-modified TiO2 inverse opals on the internal surfaces of the TiO2 porous structures. Although the photonic reflection band was not significantly varied by oxide modification, the presence of Fe2O3 in the TiO2 inverse opals enhanced their visible absorption. The conformally modified oxides on the TiO2 inverse opals could also form energy barriers and avoid the recombination of electrons and holes. The fabrication of the TiO2 photonic crystal heterostructures and modification with ZnO or Fe2O3 can enhance the photocatalytic activity of TiO2 inverse opals.

  5. Screened coulomb hybrid DFT study on electronic structure and optical properties of anionic and cationic Te-doped anatase TiO2

    KAUST Repository

    Harb, Moussab

    2013-06-27

    The origin of the enhanced visible-light optical absorption in Te-doped bulk anatase TiO2 is investigated in the framework of DFT and DFPT within HSE06 in order to ensure accurate electronic structure and optical transition predictions. Various oxidation states of Te species are considered based on their structural location in bulk TiO2. In fact, TiO (2-x)Tex (with isolated Te2- species at Te-Te distance of 8.28 Å), TiO2Tex (with isolated TeO 2- species at Te-Te distance of 8.28 Å), TiO2Te 2x (with two concomitant TeO2- species at Te-Te distance of 4.11 Å), and Ti(1-2x)O2Te2x (with two neighboring Te4+ species at nearest-neighbor Te-Te distance of 3.05 Å) show improved optical absorption responses in the visible range similarly as it is experimentally observed in Te-doped TiO2 powders. The optical absorption edges of TiO(2-x)Tex, TiO 2Tex, and TiO2Te2x are found to be red-shifted by 400 nm compared with undoped TiO2 whereas that of Ti(1-2x)O2Te2x is red-shifted by 150 nm. On the basis of calculated valence and conduction band edge positions of Te-doped TiO2, only TiO(2-x)Tex and Ti (1-2x)O2Te2x show suitable potentials for overall water splitting under visible-light irradiation. The electronic structure analysis revealed narrower band gaps of 1.12 and 1.17 eV with respect to undoped TiO2, respectively, resulting from the appearance of new occupied electronic states in the gap of TiO2. A delocalized nature of the gap states is found to be much more pronounced in TiO (2-x)Tex than that with Ti(1-2x)O 2Te2x due to the important contribution of numerous O 2p orbitals together with Te 5p orbitals. © 2013 American Chemical Society.

  6. Influence of substrate temperature and silver-doping on the structural and optical properties of TiO_2 films

    International Nuclear Information System (INIS)

    Fischer, Dieter

    2016-01-01

    Evaporation of titanium together with activated oxygen is used to grow TiO_2 films and simultaneously with silver to grow Ag–TiO_2 films (5 at.% Ag) onto sapphire substrates at three different substrate temperatures: − 190, 30, and 200 °C. The obtained films were characterized by X-ray powder diffraction, Raman, X-ray photoelectron, ultraviolet–visible spectroscopy, and transmission electron microscope investigations. The properties of TiO_2 films varied with the substrate temperature. Amorphous, transparent TiO_2 films were grown at − 190 °C and opaque, polycrystalline films at 200 °C, respectively. Surprisingly, at room temperature black, amorphous TiO_2 films are obtained which transform at 350 °C into a mixture of the anatase and brookite polymorph. In the amorphous state of the TiO_2 films a predefined rutile arrangement is suggested by Raman investigations, and the contraction of the lattice constant c of anatase phases (tetragonal, space group I 4_1/amd) depending on the substrate temperature is experimentally observed. The silver-doped TiO_2 films deposited at − 190 and 30 °C contain Ag-particles with 2 nm in size inside the TiO_2 matrix, which after annealing segregate under increasing particle sizes. The silver-doping stabilizes the anatase polymorph and yields to reduced titanium species in the films especially during deposition at 30 °C. The Ag–TiO_2 films deposited at − 190 °C are transparent up to 350 °C. In the undoped as well as silver-doped TiO_2 films the rutile polymorph is directly formed at 200 °C as main phase. - Highlights: • At room temperature black, amorphous TiO_2 films are obtained. • A predefined rutile arrangement is suggested in amorphous TiO_2 films. • Annealed TiO_2 films crystallize to a mixture of the anatase and brookite polymorph. • In TiO_2 and Ag-doped TiO_2 films the rutile polymorph is directly formed at 200 °C. • Ag-doped TiO_2 films stabilize the anatase polymorph and reduced titanium

  7. Influence of Dye Adsorbtion Time on TiO2 Dye-Sensitized Solar Cell with Krokot Extract (Portulaca Oleracea. L as A Natural Sensitizer

    Directory of Open Access Journals (Sweden)

    Didik Krisdiyanto

    2015-03-01

    Full Text Available Dye sensitized solar cells (DSSC photoelectrodes were fabricated using titanium oxide (TiO2 and sensitized with the krokot extract dye. This study investigated the effect of dye adsorption time to an efficiency of the solar cells. The fabrication cells immersed with krokot extract dye for 1, 8 and 26 hours. The photochemical performance of the DSSC showed that the open circuit voltage (Voc were 0.33, 0.036 and 0.27 V with short photocurrent density (Isc 8.00 x 10-5, 6.80 x 10-7 and 3.10 x 10-4. The photo-to-electric conversion efficiency of the DSSC reached 4.63 x 10-3 % for 26 hours adsorption time.

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

    Science.gov (United States)

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

    2017-08-01

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

  9. Enhanced photovoltaic properties of perovskite solar cells by TiO2 homogeneous hybrid structure.

    Science.gov (United States)

    Su, Pengyu; Fu, Wuyou; Yao, Huizhen; Liu, Li; Ding, Dong; Feng, Fei; Feng, Shuang; Xue, Yebin; Liu, Xizhe; Yang, Haibin

    2017-10-01

    In this paper, we fabricated a TiO 2 homogeneous hybrid structure for application in perovskite solar cells (PSCs) under ambient conditions. Under the standard air mass 1.5 global (AM 1.5G) illumination, PSCs based on homogeneous hybrid structure present a maximum power conversion efficiency of 5.39% which is higher than that of pure TiO 2 nanosheets. The enhanced properties can be explained by the better contact of TiO 2 nanosheets/nanoparticles with CH 3 NH 3 PbI 3 and fewer pinholes in electron transport materials. The advent of such unique structure opens up new avenues for the future development of high-efficiency photovoltaic cells.

  10. 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.

  11. Significantly enhanced visible light response in single TiO2 nanowire by nitrogen ion implantation

    Science.gov (United States)

    Wu, Pengcheng; Song, Xianyin; Si, Shuyao; Ke, Zunjian; Cheng, Li; Li, Wenqing; Xiao, Xiangheng; Jiang, Changzhong

    2018-05-01

    The metal-oxide semiconductor TiO2 shows enormous potential in the field of photoelectric detection; however, UV-light absorption only restricts its widespread application. It is considered that nitrogen doping can improve the visible light absorption of TiO2, but the effect of traditional chemical doping is far from being used for visible light detection. Herein, we dramatically broadened the absorption spectrum of the TiO2 nanowire (NW) by nitrogen ion implantation and apply the N-doped single TiO2 NW to visible light detection for the first time. Moreover, this novel strategy effectively modifies the surface states and thus regulates the height of Schottky barriers at the metal/semiconductor interface, which is crucial to realizing high responsivity and a fast response rate. Under the illumination of a laser with a wavelength of 457 nm, our fabricated photodetector exhibits favorable responsivity (8 A W-1) and a short response time (0.5 s). These results indicate that ion implantation is a promising method in exploring the visible light detection of TiO2.

  12. Density functional theory studies of TiO2 for photocatalysis and Li storage applications

    Science.gov (United States)

    Kim, Yong-Hoon; Lee, Ji Il; Lee, Dong Ki; Lee, Gyu Heon; Kang, Jeung Ku

    We present two theory-experiment collaboration studies of anatase TiO2 for energy applications. First, we discuss a hydrogen-nitrogen co-doped TiO2 (HN-TiO2) as a photocatalyst, and show that the interstitially introduced HN contributes to the increase of solar-to-fuel conversion efficiency. We find that the variation of valence band maximum (VBM) of NH-TiO2 extends the photoactive spectrum to the visible light, and argue that created mid-gap states produce efficient electron and hole conduction channels. Next, we consider experimentally fabricated hierarchical TiO2 nanocrystals integrated with binder-free porous graphene (PG) network foam for a Li storage application. It was found that the TiO2-PG facilitated rapid ionic transfer during the Li-ion insertion/extraction process. We clarify the mechanisms by showing that Li ion migration into the TiO2-PG interface stabilize the binder-free oxide-graphene interface. Atomistic mechanism of Li ion insertion and migration is discussed by comparing cases between an isolated Li ion, when the crowding effect is included, and when the surface Li ions are present. We found that the supply of additional surface Li ions significantly reduce the Li insertion barrier, driving a spontaneous domino-like concerted Li insertion at the oxide surface region.

  13. Nitrogen and europium doped TiO2 anodized films with applications in photocatalysis

    International Nuclear Information System (INIS)

    Chi, Choong-Soo; Choi, Jinwook; Jeong, Yongsoo; Lee, Oh Yeon; Oh, Han-Jun

    2011-01-01

    Micro-arc oxidation method is a useful process for mesoporous titanium dioxide films. In order to improve the photocatalytic activity of the TiO 2 film, N-Eu co-doped titania catalyst was synthesized by micro-arc oxidation in the H 2 SO 4 /Eu(NO 3 ) 3 mixture solution. The specific surface area and the roughness of the anodic titania film fabricated in the H 2 SO 4 /Eu(NO 3 ) 3 electrolyte, were increased compared to that of the anodic TiO 2 film prepared in H 2 SO 4 solution. The absorbance response of N-Eu titania film shows a higher adsorption onset toward visible light region, and the incorporated N and Eu ions during anodization as a dopant in the anodic TiO 2 film significantly enhanced the photocatalytic activity for dye degradation. After dye decomposition test for 3 h, dye removal rates for the anodic TiO 2 film were 60.7% and 90.1% for the N-Eu doped titania film. The improvement of the photocatalytic activity was ascribed to the synergistic effects of the surface enlargement and the new electronic state of the TiO 2 band gap by N and Eu co-doping.

  14. Foldable and Cytocompatible Sol-gel TiO2 Photonics.

    Science.gov (United States)

    Li, Lan; Zhang, Ping; Wang, Wei-Ming; Lin, Hongtao; Zerdoum, Aidan B; Geiger, Sarah J; Liu, Yangchen; Xiao, Nicholas; Zou, Yi; Ogbuu, Okechukwu; Du, Qingyang; Jia, Xinqiao; Li, Jingjing; Hu, Juejun

    2015-09-07

    Integrated photonics provides a miniaturized and potentially implantable platform to manipulate and enhance the interactions between light and biological molecules or tissues in in-vitro and in-vivo settings, and is thus being increasingly adopted in a wide cross-section of biomedical applications ranging from disease diagnosis to optogenetic neuromodulation. However, the mechanical rigidity of substrates traditionally used for photonic integration is fundamentally incompatible with soft biological tissues. Cytotoxicity of materials and chemicals used in photonic device processing imposes another constraint towards these biophotonic applications. Here we present thin film TiO2 as a viable material for biocompatible and flexible integrated photonics. Amorphous TiO2 films were deposited using a low temperature (<250 °C) sol-gel process fully compatible with monolithic integration on plastic substrates. High-index-contrast flexible optical waveguides and resonators were fabricated using the sol-gel TiO2 material, and resonator quality factors up to 20,000 were measured. Following a multi-neutral-axis mechanical design, these devices exhibit remarkable mechanical flexibility, and can sustain repeated folding without compromising their optical performance. Finally, we validated the low cytotoxicity of the sol-gel TiO2 devices through in-vitro cell culture tests. These results demonstrate the potential of sol-gel TiO2 as a promising material platform for novel biophotonic devices.

  15. Interconnected TiO2 Nanowire Networks for PbS Quantum Dot Solar Cell Applications

    Directory of Open Access Journals (Sweden)

    Fan Xu

    2012-01-01

    Full Text Available We present a simple method for the fabrication of an interconnected porous TiO2 nanostructured film via dip coating in a colloidal suspension of ultrathin TiO2 nanowires followed by high-temperature annealing. The spheroidization of the nanowires and the fusing of the loosely packed nanowire films at the contact points lead to the formation of nanopores. Using this interconnected TiO2 nanowire network for electron transport, a PbS/TiO2 heterojunction solar cell with a large short-circuit current of 2.5 mA/cm2, a Voc of 0.6 V, and a power conversion efficiency of 5.4% is achieved under 8.5 mW/cm2 white light illumination. Compared to conventional planar TiO2 film structures, these results suggest superior electron transport properties while still providing the large interfacial area between PbS quantum dots and TiO2 required for efficient exciton dissociation.

  16. 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.

  17. 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).

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

    International Nuclear Information System (INIS)

    Curulli, A.; Zane, D.

    2008-01-01

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

  19. 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

  20. PHOTODEGRADATION OF ALIZARIN S DYE USING TiO2-ZEOLITE AND UV RADIATION

    Directory of Open Access Journals (Sweden)

    Karna Wijaya

    2010-06-01

    Full Text Available An investigation of Alizarin S photodegradation using TiO2-zeolite and UV radiation was performed. TiO2-zeolite was prepared by dispersing oligocations of titanium into suspension of zeolite. The suspension was stirred and then filtered to separate the solid phase from the filtrate. the solid phase was calcined by microwave oven at 800 Watt for 5 minutes to convert the oligocations into its oxide forms. The calcined product and unmodified zeolite were characterized using x-ray diffractometry, FT-IR spectrophotometry, X-ray fluorescence and gas sorption analysis methods to determine their physicochemical properties. Photocatalytic activity of TiO2-zeolite was tested on Alizarin S solution using following method: 50 mg of zeolite was dispersed into 25 mL of 10-4 M Alizarin S. The dispersion was irradiated using 365 nm UV light at room temperature on various irradiation times, i.e. 10, 20, 30, 40 and 60 minutes. At certain irradiation time, the dispersion was filtered and the filtrate was then analyzed its concentration using UV-Vis spectrophotometry method. Characterization results exhibited that the formation of TiO2 on internal as well as external surfaces of zeolite could not be detected  with x-ray diffractometry and FT-IR spectrophotometry, however determination of titanium using x-ray fluorescence analysis on the calcined product showed that the concentration of titanium was much higher than zeolite (0.22% on zeolite and 12.08% on TiO2-zeolite. Gas sorption analysis result indicated that the the calcination  resulted in the increase of specific surface area (16,31 m2/g on zeolite and 100.96 m2/g on TiO2-zeolite as well as total pore volume of calcined product (13.34 mL/Å/g on zeolite and 57.54 mL/Å/g on TiO2-zeolite. The result of photocatalytic activitiy study showed that ca 99 % of Alizarin S was degraded by TiO2-zeolite after UV irradiation for 60 min.   Keywords: TiO2-zeolite, photocatalytic, Alizarin S.

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

    International Nuclear Information System (INIS)

    Qi Lihong; Liu Yongjun; Li Chunyan

    2010-01-01

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

  2. 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.

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

    International Nuclear Information System (INIS)

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

    2013-01-01

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

  4. Synthesis, characterization and photocatalytic activity of porous WO3/TiO2 hollow microspheres

    International Nuclear Information System (INIS)

    Yang, Liuyang; Si, Zhichun; Weng, Duan; Yao, Youwei

    2014-01-01

    Porous WO 3 /TiO 2 hollow microspheres were prepared by a spray drying method for photodegradation of methylene blue and phenol. The catalysts were characterized by X-ray diffraction, Field Emission Scanning Electron Microscope, High Resolution Transmission Electron Microscope, N 2 adsorption–desorption measurements, Raman spectrometer, UV–Vis Diffuse Reflectance Spectroscopy and Zeta-Meter measurements. The results showed that the tungsten oxides mainly existed in highly dispersed amorphous form on anatase when the loading amount of tungsten oxide was below 3 mol%. The improved photocatalytic activity under UV light irradiation of the WO 3 /TiO 2 catalyst mainly arises from the enhanced charge separation efficiency rather than the improved light absorbance by highly dispersed amorphous tungsten oxides. Highly dispersed amorphous WO x can form a shallowly trapped site due to its similar band structure with TiO 2 . The strongly electron-withdrawing of tungsten oxide in highly dispersed state facilitates the electron transition between titanium and WO x , and consequently improves the charge separation. The enhanced acidity of catalyst by WO x in reactant environment also improved the charge separation efficiency due to the timely transition of holes and electrons accumulated on TiO 2 and WO x , respectively. However, the improved photocatalytic activity under visible light irradiation of the WO 3 /TiO 2 catalyst mainly arises from light harvest. TiO 2 containing 3 mol% WO 3 displayed the highest photocatalytic activity under UV light irradiation while that containing 4 mol% WO 3 present highest activity under visible light irradiation

  5. Electronic structure of the dilute magnetic semiconductor G a1 -xM nxP from hard x-ray photoelectron spectroscopy and angle-resolved photoemission

    Science.gov (United States)

    Keqi, A.; Gehlmann, M.; Conti, G.; Nemšák, S.; Rattanachata, A.; Minár, J.; Plucinski, L.; Rault, J. E.; Rueff, J. P.; Scarpulla, M.; Hategan, M.; Pálsson, G. K.; Conlon, C.; Eiteneer, D.; Saw, A. Y.; Gray, A. X.; Kobayashi, K.; Ueda, S.; Dubon, O. D.; Schneider, C. M.; Fadley, C. S.

    2018-04-01

    We have investigated the electronic structure of the dilute magnetic semiconductor (DMS) G a0.98M n0.02P and compared it to that of an undoped GaP reference sample, using hard x-ray photoelectron spectroscopy (HXPS) and hard x-ray angle-resolved photoemission spectroscopy (HARPES) at energies of about 3 keV. We present experimental data, as well as theoretical calculations, to understand the role of the Mn dopant in the emergence of ferromagnetism in this material. Both core-level spectra and angle-resolved or angle-integrated valence spectra are discussed. In particular, the HARPES experimental data are compared to free-electron final-state model calculations and to more accurate one-step photoemission theory. The experimental results show differences between G a0.98M n0.02P and GaP in both angle-resolved and angle-integrated valence spectra. The G a0.98M n0.02P bands are broadened due to the presence of Mn impurities that disturb the long-range translational order of the host GaP crystal. Mn-induced changes of the electronic structure are observed over the entire valence band range, including the presence of a distinct impurity band close to the valence-band maximum of the DMS. These experimental results are in good agreement with the one-step photoemission calculations and a prior HARPES study of G a0.97M n0.03As and GaAs [Gray et al., Nat. Mater. 11, 957 (2012), 10.1038/nmat3450], demonstrating the strong similarity between these two materials. The Mn 2 p and 3 s core-level spectra also reveal an essentially identical state in doping both GaAs and GaP.

  6. Origin of the Enhanced Visible-Light Absorption in N-Doped Bulk Anatase TiO 2 from First-Principles Calculations

    KAUST Repository

    Harb, Moussab; Sautet, P.; Raybaud, P.

    2011-01-01

    unambiguously that the diamagnetic TiO(2-3x)N2x system exhibits the enhanced optical absorption in N-doped TiO2 under visible-light irradiation. Electronic analysis further reveals a band gap narrowing of 0.6 eV induced by delocalized impurity states located

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

    Science.gov (United States)

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

    2018-02-01

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

  8. Characterization, Cytotoxicity, and Genotoxicity of TiO2 and Folate-Coupled Chitosan Nanoparticles Loading Polyprenol-Based Nanoemulsion.

    Science.gov (United States)

    Tao, Ran; Wang, Chengzhang; Zhang, Changwei; Li, WenJun; Zhou, Hao; Chen, Hongxia; Ye, Jianzhong

    2018-07-01

    The structure and bioactivity of Ginkgo biloba leaves polyprenol (GBP) are similar to that of dolichol which widely exists in human and mammalian organs. GBP possesses potential pharmacological activities against cancer. This study involved oil-in-water type nanoemulsion (NE) loading GBP was prepared by dissolving polyprenol in nanoemulsion of sodium tripolyphosphate (TPP)/TiO 2 solution, Triton X-100, and 1-octanol by inversed-phase emulsification (EIP) and ultrasonic emulsification (UE) method. Folic acid (FA)-coupled chitosan (CS) nanoparticles (NPs), GBP-FA-CS-NPs and GBP-TiO 2 -FA-CS-NPs, were fabricated by ionic cross-linking of positively charged FA-CS conjugates and negatively charged nanoemulsion with TPP/TiO 2 . And characterizations of them were investigated by TEM, SEM, FTIR, particle size, and zeta potential. The cytotoxic and genotoxic effects of GBP-TiO 2 -FA-CS-NP treatment were higher than GBP-NE, GBP-FA-CS-NPs, TiO 2 -NE, GBP-TiO 2 -NE, TiO 2 -FA-CS-NPs, and GBP-TiO 2 -FA-CS-NP treatment at the same tested concentrations in HepG2 cells. GBP-TiO 2 -FA-CS-NPs at low TiO 2 concentration (from 1 to 2.5 μg/ml) showed good inhibition capacity on HepG2 cells and low cytotoxic and genotoxic effects on HL-7702 cells. The possible mechanism of cytotoxicity on GBP-TiO 2 -FA-CS-NPs against HepG2 cells is by preventing excessive intracellular Ca 2+ into extracellular spaces via inhibiting Ca 2+ -ATPase and Ca 2+ /Mg 2+ -ATPase.

  9. Synthesis and Photocatalytic Activity of Mo-Doped TiO2 Nanoparticles

    Directory of Open Access Journals (Sweden)

    Ji-guo Huang

    2015-01-01

    Full Text Available The undoped and Mo-doped TiO2 nanoparticles were synthesized by sol-gel method. The as-prepared samples were characterized by X-ray diffraction (XRD, diffuse reflectance UV-visible absorption spectra (UV-vis DRS, X-ray photoelectron spectra (XPS, and transmission electron microscopy (TEM. The photocatalytic activity was evaluated by photocatalytic degradation of methylene blue under irradiation of a 500 W xenon lamp and natural solar light outdoor. Effects of calcination temperatures and Mo doping amounts on crystal phase, crystallite size, lattice distortion, and optical properties were investigated. The results showed that most of Mo6+ took the place of Ti4+ in the crystal lattice of TiO2, which inhibited the growth of crystallite size, suppressed the transformation from anatase to rutile, and led to lattice distortion of TiO2. Mo doping narrowed the band gap (from 3.05 eV of TiO2 to 2.73 eV of TiMo0.02O and efficiently increased the optical absorption in visible region. Mo doping was shown to be an efficient method for degradation of methylene blue under visible light, especially under solar light. When the calcination temperature was 550°C and the Mo doping amount was 2.0%, the Mo-doped TiO2 sample exhibited the highest photocatalytic activity.

  10. Preparation and Characterization of TiO2/CdS Layers as Potential Photoelectrocatalytic Materials

    Directory of Open Access Journals (Sweden)

    Teofil-Danut Silipas

    2011-01-01

    Full Text Available The TiO2/CdS semiconductor composites were prepared on
    indium tin oxide (ITO substrates in di®erent mass proportions via wet-chemical techniques using bi-distilled water, acetyl-acetone, poly-propylene-glycol and Triton X-100 as additives. The composite layers were annealed in normal conditions at the temperature of 450±C, 120 min. with a rate of temperature increasing of 5±C/min. The structural and optical properties of all the TiO2/CdS ayers were characterized by X-ray di®raction, UV-VIS spectroscopy, spectrofluorimetry and FT/IR microscopy. The microstructural properties of the deposited TiO2/CdS layers can be modi¯ed by varying the mass proportions of TiO2:CdS. The good crystallinity level and the high optical adsorption of
    the TiO2/CdS layers make them attractive for photoelectrochemical cell applications.

  11. Magneto-optical spectroscopy of diluted magnetic oxides TiO2-δ: Co

    International Nuclear Information System (INIS)

    Gan'shina, E.A.; Granovsky, A.B.; Orlov, A.F.; Perov, N.S.; Vashuk, M.V.

    2009-01-01

    We report an experimental study on transversal Kerr effect (TKE) in magnetic oxide semiconductors TiO 2-δ :Co. The TiO 2-δ : Co thin films were deposited on LaAlO 3 (0 0 1) substrates by magnetron sputtering in the argon-oxygen atmosphere at oxygen partial pressure of 2x10 -6 -2x10 -4 Torr. It was obtained that TKE spectra in ferromagnetic samples are extremely sensitive to the Co-volume fraction, the crystalline structure, and technology parameters. The observed well-pronounced peaks in TKE spectra for anatase Co-doped TiO 2-δ films at low Co ( 2-δ matrix that indicates on intrinsic ferromagnetism in these samples. With increase of Co-volume fraction up to 5-8% the fine structure of TKE spectra disappears and magneto-optical response in reflection mode becomes larger than that for thick Co films

  12. Magnetic and structural study of Cu-doped TiO2 thin films

    International Nuclear Information System (INIS)

    Torres, C.E. Rodriguez; Golmar, F.; Cabrera, A.F.; Errico, L.; Navarro, A.M. Mudarra; Renteria, M.; Sanchez, F.H.; Duhalde, S.

    2007-01-01

    Transparent pure and Cu-doped (2.5, 5 and 10 at.%) anatase TiO 2 thin films were grown by pulsed laser deposition technique on LaAlO 3 substrates. The samples were structurally characterized by X-ray absorption spectroscopy and X-ray diffraction. The magnetic properties were measured using a SQUID. All films have a FM-like behaviour. In the case of the Cu-doped samples, the magnetic cycles are almost independent of the Cu concentration. Cu atoms are forming CuO and/or substituting Ti in TiO 2 . The thermal treatment in air promotes the CuO segregation. Since CuO is antiferromagnetic, the magnetic signals present in the films could be assigned to Cu substitutionally replacing cations in TiO 2

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

    Science.gov (United States)

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

    2018-01-01

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

  14. Synthesis of LaVO4/TiO2 heterojunction nanotubes by sol-gel coupled with hydrothermal method for photocatalytic air purification.

    Science.gov (United States)

    Zou, Xuejun; Li, Xinyong; Zhao, Qidong; Liu, Shaomin

    2012-10-01

    With the aim of improving the effective utilization of visible light, the LaVO(4)/TiO(2) heterojunction nanotubes were fabricated by sol-gel coupled with hydrothermal method. The photocatalytic ability was demonstrated through catalytic removal of gaseous toluene species. The nanotube samples were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), surface photovoltage (SPV), Raman spectra and N(2) adsorption-desorption measurements. The characterization results showed that the samples with high specific surface areas were of typical nanotubular morphology, which would lead to the high separation and transfer efficiency of photo induced electron-hole pairs. The as-prepared nanotubes exhibited high photocatalytic activity in decomposing toluene species under visible light irradiation with fine photochemical stability. The enhanced photocatalytic performance of LaVO(4)/TiO(2) nanotubes might be attributed to the matching band potentials, the interconnected heterojunction of LaVO(4) versus TiO(2), and the large specific surface areas of nanotubes. Copyright © 2012 Elsevier Inc. All rights reserved.

  15. Synthesis and Characterization of Stable and Binder-Free Electrodes of TiO2 Nanofibers for Li-Ion Batteries

    Directory of Open Access Journals (Sweden)

    Phontip Tammawat

    2013-01-01

    Full Text Available An electrospinning technique was used to fabricate TiO2 nanofibers for use as binder-free electrodes for lithium-ion batteries. The as-electrospun nanofibers were calcined at 400–1,000°C and characterized using X-ray diffraction (XRD, scanning electron microscopy (SEM, and transmission electron microscopy (TEM. SEM and TEM images showed that the fibers have an average diameter of ~100 nm and are composed of nanocrystallites and grains, which grow in size as the calcination temperature increases. The electrochemical properties of the nanofibers were evaluated using galvanostatic cycling and electrochemical impedance spectroscopy. The TiO2 nanofibers calcined at 400°C showed higher electronic conductivity, higher discharge capacity, and better cycling performance than the nanofibers calcined at 600, 800, and 1,000°C. The TiO2 nanofibers calcined at 400°C delivered an initial reversible capacity of 325 mAh·g−1 approaching their theoretical value at 0.1 C rate and over 175 mAh·g−1 at 0.3 C rate with limited capacity fading and Coulombic efficiency between 96 and 100%.

  16. Thermal characteristics, Raman spectra, optical and structural properties of TiO2-Bi2O3-B2O3-TeO2 glasses

    Science.gov (United States)

    Gupta, Nupur; Khanna, Atul; Gonzàlez, Fernando; Iordanova, Reni

    2017-05-01

    Tellurite and borotellurite glasses containing Bi2O3 and TiO2 were prepared and structure-property correlations were carried out by density measurements, X-ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), Raman and UV-visible spectroscopy. Titanium tellurite glasses require high melt-cooling rates and were fabricated by splat quenching. On adding B2O3, the glass forming ability (GFA) enhances, and glasses could be synthesized at lower quenching rates. The density of glasses shows a direct correlation with molecular mass of the constituents. UV-visible studies were used to determine the optical band gap and refractive index. Raman studies found that the co-ordination number of tellurium ions with oxygen (NTe-O) decreases with the increase in B2O3 as well as Bi2O3 content while, TiO2 produce only a small decrease in NTe-O, which explains the lower GFA of titanium tellurite glasses that do not contain Bi2O3 and B2O3. DSC studies show that the glass transition temperature (Tg) increases with B2O3 and TiO2 concentrations and that Tg correlates well with bond enthalpy of the metal oxides.

  17. 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

  18. Textural, structural and electrical properties of TiO2 nanoparticles using Brij 35 and P123 as surfactants

    Directory of Open Access Journals (Sweden)

    Dora Solís et al

    2008-01-01

    Full Text Available The effect of the use of the triblock copolymer Pluronic P123[(PEO20(PPO70(PEO20, Aldrich] and the non-ionic polyoxyethylene-lauryl ether Brij 35 as surfactants on the textural, structural and electrical properties of nanosized TiO2 is analyzed in this work. The as-obtained samples were thermally treated at 400 °C to eliminate the surfactant, promote dehydroxylation and crystallize the sample. The TiO2 samples were characterized by thermal analysis, N2 physisorption, x-ray diffraction analysis, micro-Raman spectroscopy and scanning electron microscopy. To evaluate the TiO2 electrical features, I–V data were obtained. The x-ray diffraction results show that in the chemical synthesis using surfactants, the crystallite size is smaller than that of the commercial sample. The Raman spectroscopy results clearly indicate that, when P123 is used, the anatase phase of TiO2 is obtained, whereas when Brij 35 is used a mixture of the anatase and brookite phases is obtained. The specific surface area and crystallite size of the TiO2 prepared as indicated above are higher and smaller, respectively, than the corresponding properties found in commercial TiO2. The I–V plot showed a nonlinear behavior of the nanosized TiO2. The samples obtained with P123 showed the best electrical conductivity.

  19. Visible photoenhanced current-voltage characteristics of Au : TiO2 nanocomposite thin films as photoanodes

    International Nuclear Information System (INIS)

    Naseri, N; Amiri, M; Moshfegh, A Z

    2010-01-01

    In this investigation, the effect of annealing temperature and concentration of gold nanoparticles on the photoelectrochemical properties of sol-gel deposited Au : TiO 2 nanocomposite thin films is studied. Various gold concentrations have been added to the TiO 2 thin films and their properties are compared. All the deposited samples are annealed at different temperatures. The optical density spectra of the films show the formation of gold nanoparticles in the films. The optical bandgap energy of the Au : TiO 2 films decreases with increasing Au concentration. The crystalline structure of the nanocomposite films is studied by x-ray diffractometry indicating the formation of gold nanocrystals in the anatase TiO 2 nanocrystalline thin films. X-ray photoelectron spectroscopy reveals that the presence of gold in the metallic state and the formation of TiO 2 are stoichiometric. The photoelectrochemical properties of the Au : TiO 2 samples are characterized using a compartment cell containing H 2 SO 4 and KOH as cathodic and anodic electrolytes, respectively. It is found that the addition of Au nanoparticles in TiO 2 films enhances the photoresponse of the layer and the addition of gold nanocrystals with an optimum value of 5 mol% resulted in the highest photoelectrochemical activity. Moreover, the photoresponse of the samples is also enhanced with an increase in the annealing temperature.

  20. 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.

  1. Effect of zinc doping on the bandgap and photoluminescence of Zn2+-doped TiO2 nanowires

    Science.gov (United States)

    Loan, Trinh Thi; Huong, Vu Hoang; Tham, Vu Thi; Long, Nguyen Ngoc

    2018-03-01

    This study was focused on the effect of Zn2+ dopant concentration on the absorption edge and photoluminescence of anatase TiO2 nanowires synthesized by hydrothermal technique. For the undoped anatase TiO2 nanowires, the indirect band gap of 3.26 eV and the direct band gap of 3.58 eV are assigned to the indirect Γ3 → X1b and direct X2b → X1b transitions, respectively. The Zn2+-doping makes the absorption edge of TiO2:Zn2+ nanowires shift towards the lower energy side (red shift). On the other hand, the replacing Ti4+ ions with Zn2+ ions creates oxygen vacancies (VO) and shallow defects associated with VO. Just these defects are responsible for the enhanced luminescence of Zn2+-doped TiO2 nanowires.

  2. Mesoporous TiO2 Micro-Nanometer Composite Structure: Synthesis, Optoelectric Properties, and Photocatalytic Selectivity

    Directory of Open Access Journals (Sweden)

    Kun Liu

    2012-01-01

    Full Text Available Mesoporous anatase TiO2 micro-nanometer composite structure was synthesized by solvothermal method at 180°C, followed by calcination at 400°C for 2 h. The as-prepared TiO2 was characterized by X-ray diffraction (XRD, scanning electron microscope (SEM, transmission electron microscope (TEM, and Fourier transform infrared spectrum (FT-IR. The specific surface area and pore size distribution were obtained from N2 adsorption-desorption isotherm, and the optoelectric property of the mesoporous TiO2 was studied by UV-Vis absorption spectrum and surface photovoltage spectra (SPS. The photocatalytic activity was evaluated by photodegradation of sole rhodamine B (RhB and sole phenol aqueous solutions under simulated sunlight irradiation and compared with that of Degussa P-25 (P25 under the same conditions. The photodegradation preference of this mesoporous TiO2 was also investigated for an RhB-phenol mixed solution. The results show that the TiO2 composite structure consists of microspheres (∼0.5–2 μm in diameter and irregular aggregates (several hundred nanometers with rough surfaces and the average primary particle size is 10.2 nm. The photodegradation activities of this mesoporous TiO2 on both RhB and phenol solutions are higher than those of P25. Moreover, this as-prepared TiO2 exhibits photodegradation preference on RhB in the RhB-phenol mixture solution.

  3. Fabrication techniques of X-ray spiral zone plates

    International Nuclear Information System (INIS)

    Gao Nan; Zhu Xiaoli; Li Hailiang; Xie Changqing

    2010-01-01

    The techniques to make X-ray spiral zone plates using electron beam and X-ray lithography were studied. A master mask was fabricated on polyimide membrane by E-beam lithography and micro-electroplating. Spiral zone plates were efficiently replicated by X-ray lithography and micro-electroplating. By combining the techniques, spiral zone plates at 1 keV were successfully fabricate. With an outermost zone width of the 200 nm, and the gold absorbers thickness of 700 nm, the high quality zone plates can be used for X-ray phase contrast microscopy.(authors)

  4. Pilot-plant evaluation of TiO2 and TiO2-based hybrid photocatalysts for solar treatment of polluted water.

    Science.gov (United States)

    Andronic, Luminita; Isac, Luminita; Miralles-Cuevas, Sara; Visa, Maria; Oller, Isabel; Duta, Anca; Malato, Sixto

    2016-12-15

    Materials with photocatalytic and adsorption properties for advanced wastewater treatment targeting reuse were studied. Making use of TiO 2 as a well-known photocatalyst, Cu 2 S as a Vis-active semiconductor, and fly ash as a good adsorbent, dispersed mixtures/composites were prepared to remove pollutants from wastewater. X-ray diffraction, scanning electron microscopy, energy-dispersive X-Ray spectroscopy, atomic force microscopy, band gap energy, point of zero charge (pH pzc ) and BET porosity were used to characterize the substrates. Phenol, imidacloprid and dichloroacetic acid were used as pollutants for photocatalytic activity of the new photocatalysts. Experiments using the new dispersed powders were carried out at laboratory scale in two solar simulators and under natural solar irradiation at the Plataforma Solar de Almería, in a Compound Parabolic Collector (CPC) for a comparative analysis of pollutants removal and mineralization efficiencies, and to identify features that could facilitate photocatalyst separation and reuse. The results show that radiation intensity significantly affects the phenol degradation rate. The composite mixture of TiO 2 and fly ash is 2-3 times less active than sol-gel TiO 2 . Photodegradation kinetic data on the highly active TiO 2 are compared for pollutants elimination. Photodegradation of dichloroacetic acid was fast and complete after 90min in the CPC, while after 150min imidacloprid and phenol removal was 90% and 56% respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Pilot-plant evaluation of TiO_2 and TiO_2-based hybrid photocatalysts for solar treatment of polluted water

    International Nuclear Information System (INIS)

    Andronic, Luminita; Isac, Luminita; Miralles-Cuevas, Sara; Visa, Maria; Oller, Isabel; Duta, Anca; Malato, Sixto

    2016-01-01

    Materials with photocatalytic and adsorption properties for advanced wastewater treatment targeting reuse were studied. Making use of TiO_2 as a well-known photocatalyst, Cu_2S as a Vis-active semiconductor, and fly ash as a good adsorbent, dispersed mixtures/composites were prepared to remove pollutants from wastewater. X-ray diffraction, scanning electron microscopy, energy-dispersive X-Ray spectroscopy, atomic force microscopy, band gap energy, point of zero charge (pH_p_z_c) and BET porosity were used to characterize the substrates. Phenol, imidacloprid and dichloroacetic acid were used as pollutants for photocatalytic activity of the new photocatalysts. Experiments using the new dispersed powders were carried out at laboratory scale in two solar simulators and under natural solar irradiation at the Plataforma Solar de Almería, in a Compound Parabolic Collector (CPC) for a comparative analysis of pollutants removal and mineralization efficiencies, and to identify features that could facilitate photocatalyst separation and reuse. The results show that radiation intensity significantly affects the phenol degradation rate. The composite mixture of TiO_2 and fly ash is 2-3 times less active than sol-gel TiO_2. Photodegradation kinetic data on the highly active TiO_2 are compared for pollutants elimination. Photodegradation of dichloroacetic acid was fast and complete after 90 min in the CPC, while after 150 min imidacloprid and phenol removal was 90% and 56% respectively.

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

    International Nuclear Information System (INIS)

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

    2012-01-01

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

  7. Cluster synthesis of monodisperse rutile-TiO2 nanoparticles and dielectric TiO2-vinylidene fluoride oligomer nanocomposites

    International Nuclear Information System (INIS)

    Balasubramanian, Balamurugan; Kraemer, Kristin L; Valloppilly, Shah R; Ducharme, Stephen; Sellmyer, David J

    2011-01-01

    The embedding of oxide nanoparticles in polymer matrices produces a greatly enhanced dielectric response by combining the high dielectric strength and low loss of suitable host polymers with the high electric polarizability of nanoparticles. The fabrication of oxide-polymer nanocomposites with well-controlled distributions of nanoparticles is, however, challenging due to the thermodynamic and kinetic barriers between the polymer matrix and nanoparticle fillers. In the present study, monodisperse TiO 2 nanoparticles having an average particle size of 14.4 nm and predominant rutile phase were produced using a cluster-deposition technique without high-temperature thermal annealing and subsequently coated with uniform vinylidene fluoride oligomer (VDFO) molecules using a thermal evaporation source, prior to deposition as TiO 2 -VDFO nanocomposite films on suitable substrates. The molecular coatings on TiO 2 nanoparticles serve two purposes, namely to prevent the TiO 2 nanoparticles from contacting each other and to couple the nanoparticle polarization to the matrix. Parallel-plate capacitors made of TiO 2 -VDFO nanocomposite film as the dielectric exhibit minimum dielectric dispersion and low dielectric loss. Dielectric measurements also show an enhanced effective dielectric constant in TiO 2 -VDFO nanocomposites as compared to that of pure VDFO. This study demonstrates for the first time a unique electroactive particle coating in the form of a ferroelectric VDFO that has high-temperature stability as compared to conventionally used polymers for fabricating dielectric oxide-polymer nanocomposites.

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

    Science.gov (United States)

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

    2016-03-01

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

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

    International Nuclear Information System (INIS)

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

    2016-01-01

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

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

    Science.gov (United States)

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

    2015-11-01

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

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

    International Nuclear Information System (INIS)

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

    2017-01-01

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

  12. 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.

  13. Water Adsorption on TiO2

    DEFF Research Database (Denmark)

    Hammer, Bjørk; Wendt, Stefan; Besenbacher, Flemming

    2010-01-01

    Scanning Tunneling Microscopy (STM) studies and Density Functional Theory (DFT) investigations of the interaction of water with the rutile TiO2 (110) surface are summarized. From high-resolution STM the following reactions have been revealed: water adsorption and diffusion in the Ti troughs, water...... dissociation in bridging oxygen vacancies, assembly of adsorbed water monomers into rapidly diffusing water dimers, and formation of water dimers by reduction of oxygen molecules. The STM results are rationalized based on DFT calculations, revealing the bonding geometries and reaction pathways of the water...

  14. Continuous-Flow Photocatalytic Degradation of Organics Using Modified TiO2 Nanocomposites

    Directory of Open Access Journals (Sweden)

    Imran Ali

    2018-01-01

    Full Text Available In this study, TiO2 nanotubes (TNTs were fabricated on a Ti sheet following the anodic oxidation method and were decorated with reduced graphene oxide (RGO, graphene oxide (GO, and bismuth (Bi via electrodeposition. The surface morphologies, crystal structures, and compositions of the catalyst were characterized by field emission scanning electron microscopy, Auger electron spectroscopy, X-ray diffraction, photoluminance spectra, X-ray photoelectron spectroscopy, and energy dispersive X-ray spectroscopy. The TNTs loaded with RGO, GO, and Bi were used in a continuous-flow system as photocatalysts for the degradation of methylene blue (MB dye. It was found that the TNTs are efficient photocatalysts for the removal of color from water; upon UV irradiation on TNTs, the MB removal ratio was ~89%. Moreover, the photocatalytic activities of the decorated TNTs were higher than that of pristine TNTs in visible light. In comparison with TNTs, the rate of MB removal in visible light was increased by a factor of 3.4, 3.2, and 2.9 using RGO-TNTs, Bi-TNTs, and GO-TNTs, respectively. The reusability of the catalysts were investigated, and their quantum efficiencies were also calculated. The cylindrical anodized TNTs were excellent photocatalysts for the degradation of organic pollutants. Thus, it was concluded that the continuous-flow photocatalytic reactor comprising TNTs and modified TNTs is suitable for treating wastewater in textile industries.

  15. Catalysis of a Nanometre Solid Super Acid of SO42-/TiO2 on the Thermal Decomposition of Ammonium Nitrate

    Directory of Open Access Journals (Sweden)

    Xiaolan Song

    2016-03-01

    Full Text Available Raw TiO2 nanoparticles were prepared using the hydroly‐ sis of TiCl4. The nanoparticles were subjected to a surface treatment in diluted sulphuric acid and, subsequently, calcined at different temperatures. Then, a type of super solid acid (SO42-/TiO2 with particle sizes of 20∼30 nm was fabricated. The catalysis of SO42-/TiO2 on the thermolysis of ammonium nitrate (AN was probed using thermal analysis. For SO42-/TiO2 (AN doped with 3%SO42-/TiO2, the onset temperature decreased by 19°C and the peak tem‐ perature decreased by 15.8°C. For TiO2 (AN doped with 3%TiO2, the peak temperature decreased by only 0.5°C. Using the DSC-IR technology, the gas products of the decomposition of 3%SO42-/TiO2-doped AN were detected. We found that the products were mainly N2O (g and a small amount of H2O (g, and that no NH3 (g or HNO3 (g was detected, which ascertained the decomposition reaction of NH4NO3→N2O(g+H2O(g. In addition, the catalysis mechanism of SO42-/TiO2 on the AN decomposi‐ tion was discussed in detail.

  16. Nano-MnO2@TiO2 microspheres: A novel structure and excellent performance as anode of lithium-ion batteries

    Science.gov (United States)

    Cao, Zhiguang; Chen, Xiaoqiao; Xing, Lidang; Liao, Youhao; Xu, Mengqing; Li, Xiaoping; Liu, Xiang; Li, Weishan

    2018-03-01

    A structurally hierarchical MnO2/TiO2 composite (Nano-MnO2@TiO2) is fabricated by calcining MnCO3 microspheres and coating a thin layer of TiO2 through the heat decomposition of tetrabutyl titanate, and evaluated as anode of gravimetrically and volumetrically high energy density lithium ion battery. The characterizations from FESEM, TEM, HRTEM and XRD, indicate that the resulting Nano-MnO2@TiO2 takes a spherical morphology with a core of about 2 μm in diameter, consisting of compact MnO2 nanoparticles, and a shell of 60 nm thick, consisting of smaller TiO2 nanoparticles. The charge/discharge tests demonstrate that Nano-MnO2@TiO2 exhibits excellent performance as anode of lithium ion battery, delivering a capacity of 938 mAh g-1 at 300 mA g-1 after 200 cycles, compared to the 103 mAh g-1 of the uncoated sample. The microsphere consisting of compact nanoparticles provides Nano-MnO2@TiO2 with high specific gravity. The dimensionally and structurally stable TiO2 maintains the integrity of MnO2 microspheres and facilitates lithium insertion/extraction. This unique structure yields the excellent cyclic stability and rate capability of Nano-MnO2@TiO2.

  17. Synthesis and Mechanical Properties Investigation of Nano TiO2/Glass/Epoxy Hybrid Nanocomposite

    Directory of Open Access Journals (Sweden)

    Hamid Reza Salehi

    2015-10-01

    Full Text Available Mechanical properties of epoxy and glass/epoxy filled with 0.25, 0.5 and 1 vol% of TiO2 nanoparticles have been studied using tensile and three-point bending tests. For the TiO2/epoxy nanocomposites, the results showed that the strength and stiffness were improved, though the strain at ultimate strength point and breaking strain decreased. Moreover, the hybrid nanocomposites composed of 4 layers of woven E-glass fabric and TiO2/epoxy matrix were fabricated and cut onaxis and 45° off-axis by water jet. The results of tensile and three-point bending tests indicated a remarkable improvement in the strength and stiffness that could not be related to the mechanical improvement of the matrix. The samples containing 1 vol% nano TiO2 were improved relative to samples without the nanoparticles. The tensile strength of the on-axis and off-axis samples containing 1 vol% TiO2 increased by about 25.9% and 17.9%, in the order given, compared to that of the glass/epoxy specimens. In three-point bending test, the strength of the on-axis and off-axis specimens was improved 26% and 23.2%, respectively. In addition, the tensile stiffness of the onaxis and off-axis samples containing 1 vol% TiO2 increased, respectively, by about 14.4% and 17.5% compared to that of the glass/epoxy specimens. Also for the same on-axis and off-axis samples the three-point bending stiffness increased about 19.8% and 14.6%, respectively. The whole investigation on the microstructure of the hybrid nanocomposites illustrated that stronger interfaces between the fiber and TiO2/epoxy matrix were formed and improvement was noticed on mechanical properties of ternary composite compared to those of the fiber/epoxy composites. The analysis of damage zones of hybrid nanocomposites showed that the surface area of the damaged zone declined considerably due to the brittle behavior of TiO2-filled specimens but the area below the stress-strain curve, showing energy absorption during the test

  18. Enhanced performance of dye-sensitized solar cells based on organic dopant incorporated PVDF-HFP/PEO polymer blend electrolyte with g-C3N4/TiO2 photoanode

    International Nuclear Information System (INIS)

    Senthil, R.A.; Theerthagiri, J.; Madhavan, J.; Murugan, K.; Arunachalam, Prabhakarn; Arof, A.K.

    2016-01-01

    This work describes the effect of 2-aminopyrimidine (2-APY) on poly(vinylidinefluoride-co-hexafluoropropylene) (PVDF-HFP)/polyethylene oxide (PEO) blend polymer electrolyte along with binary iodide salts (tetrabutylammonium iodide (TBAI) and potassium iodide (KI)) and iodine (I 2 ) were studied for enhancing the efficiency of the dye-sensitized solar cells (DSSCs) consisting of g-C 3 N 4 /TiO 2 composite as photoanode. The g-C 3 N 4 was synthesized from low cost urea by thermal condensation method. It was used as a precursor to synthesize the various weight percentage ratios (5%, 10% and 15%) of g-C 3 N 4 /TiO 2 composites by wet-impregnation method. The pure and 2-APY incorporated PVDF-HFP/PEO polymer blend electrolytes were arranged by wet chemical process (casting method) using DMF as a solvent. The synthesized g-C 3 N 4 /TiO 2 composites and polymer blend electrolytes were studied and analyzed by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffractometer (XRD) and scanning electron microscopy (SEM). The ionic conductivity values of the pure and 2-APY incorporated PVDF-HFP/PEO blend electrolytes were estimated to be 4.53×10 −5 and 1.87×10 −4 Scm −1 respectively. The UV–vis absorption spectroscopy was carried out for the pure and different wt% of g-C 3 N 4 /TiO 2 composites coated FTO films after N3 dye-sensitization. The 10 wt% g-C 3 N 4 /TiO 2 composite film showed a maximum absorption compared to the others. The DSSC assembled with 10 wt% g-C 3 N 4 /TiO 2 as photoanode using the pure polymer blend electrolyte exhibited a power conversion efficiency (PCE) of 3.17% , which was superior than that of DSSC based pure TiO 2 (2.46%). However, the PCE was increased to 4.73% for the DSSC assembled using 10 wt% g-C 3 N 4 /TiO 2 as photoanode with 2-APY incorporated polymer blend electrolyte. Hence, the present study is a successful attempt to provide a new pathway to enhance the performance of DSSCs. - Graphical abstract: In this study, the g-C 3 N

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

    Science.gov (United States)

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

    2017-08-01

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

  20. 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.

  1. Structure and photocatalytic activity studies of TiO2-supported over Ce-modified Al-MCM-41

    International Nuclear Information System (INIS)

    Krishna Reddy, Jakkidi; Durgakumari, Valluri; Subrahmanyam, Machiraju; Sreedhar, Bojja

    2009-01-01

    Ce-Al-MCM-41, TiO 2 /Al-MCM-41 and TiO 2 /Ce-Al-MCM-41 materials with varying contents of Ce (by impregnation) and TiO 2 loaded (by solid-state dispersion) on Al-MCM-41 support are prepared. The Ce modified and TiO 2 loaded composite systems are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectra (DRS) and X-ray photoelectron spectroscopy (XPS) techniques. The DRS and XPS of low Ce content (0.2-0.5 wt.%) modified Al-MCM-41 samples are showing more characteristic of Ce 3+ species wherein cerium in interaction with Al-MCM-41 and that of high Ce (0.8, 3.0 wt.%) content modified samples are showing the characteristic of both Ce 4+ and Ce 3+ species. A series of Ce-modified Al-MCM-41 and TiO 2 loaded composite catalysts are evaluated for photocatalytic degradation of phenol under UV irradiation. Low Ce content in Ce 3+ state on Al-MCM-41 is showing good photoactivity in comparison with high Ce content samples and pure ceria. The composite TiO 2 /Ce-Al-MCM-41 is showing enhanced degradation activity due decreased rate of electron-hole recombination on TiO 2 surface by the redox properties of cerium. The photocatalyst TiO 2 /Ce-Al-MCM-41 with an optimum of 10 wt.% TiO 2 and 0.3 wt.% Ce is showing maximum phenol degradation activity. The possible mechanism of phenol degradation on the composite photocatalyst is proposed.

  2. Elaboration and Characterization of TiO2 and Study of the Influence of The Number of Thin Films on the Methylene Blue Adsorption Rate

    Science.gov (United States)

    Madoui, Karima; Medjahed, Aicha; Hamici, Melia; Djamila, Abdi; Boudissa, Mokhtar

    2018-05-01

    Thin films of titanium oxide (TiO2) deposited on glass substrates were fabricated by using the sol-gel route. The realization of these thin layers was made using the dip-coating technique with a solution of titanium isopropoxyde as a precursor. The samples prepared with different numbers of deposited layers were annealed at 400 ° C for 2 hours. The main purposes of this work were investigations of both the effect of the number of thin TiO2 layers on the crystal structure of the anatase form first and, their ability to adsorb the solution of methylene blue in order to make colored filters from a photocatalytic process. The deposited titanium-oxide layers were characterized by using various techniques: namely, X-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM) and UV-Visible spectrometry. The result obtained by using the XRD technique showed the appearance of an anatase phase, as was confirmed by using Raman spectroscopy. The AFM surface analysis allowed the surface topography to be characterized and the surface roughness to be measured, which increased with increasing number of layers. The UV-Visible spectra showed that the TiO2 films had a good transmittance varying from 65% to 95% according to the number of layers. The gap energy varied as a function of the number of deposited layers. The as deposited TiO2 layers were tested as a photocatalyst towards the adsorption of methylene blue dye. The results obtained during this study showed that the adsorption capacity varied according to the number of deposited thin layers and the exposing duration to ultraviolet (UV) light. The maximum absorption rate of the dye was obtained for the two-layer sample. Seventy-two hours of irradiation allowed the adsorption intensity of the dye to be maximized for two-layer films.

  3. 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.

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

    Science.gov (United States)

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

    2018-05-01

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

  5. Preparation of Silver Immobilised TiO2-Hectorite for Phenol Removal and Eschericia coli Desinfection

    Directory of Open Access Journals (Sweden)

    Is Fatimah

    2013-03-01

    Full Text Available Preparation of silver immobilized TiO2-Hectorite and its application in phenol photooxidation and Eschericia coli bacteria desinfection has been conducted. Material was obtained by two steps of synthesis: preparation of TiO2-Hectorite and silver immobilization into TiO2-Hectorite. Physico-chemical characterization to the prepared material compared to raw hectorite was conducted by X-ray Diffraction, gas sorption analyzer, scanning electron microscope and DRUV-Visible spectrophotometry and for photoactivity study, phenol photooxidation and Eschericia coli desinfection were investigated. The results indicated that the modification to hectorite material improve the physico-chemical character related to its role as photo-catalyst. Kinetic study of phenol photooxidation revealed the role of TiO2 pillarization and silver immobilization in enhancing rate of reaction as well as increased photoactivity of the materials in E. coli desinfection. © 2013 BCREC UNDIP. All rights reservedReceived: 28th September 2012; Revised: 7th December 2012; Accepted: 20th Decemberber 2012[How to Cite: I. Fatimah (2013. Preparation of Silver Immobilised TiO2-Hectorite for Phenol Removal and Eschericia coli Desinfection. Bulletin of Chemical Reaction Engineering & Catalysis, 7 (3: 191-197. (doi:10.9767/bcrec.7.3.4047.191-197][Permalink/DOI: http://dx.doi.org/10.9767/bcrec.7.3.4047.191-197 ] View in  |

  6. Photosensitization of TiO2 P25 with CdS Nanoparticles for Photocatalytic Applications

    Directory of Open Access Journals (Sweden)

    Trenczek-Zając A.

    2017-06-01

    Full Text Available A TiO2/CdS coupled system was prepared by mixing the TiO2 P25 with CdS synthesized by means of the precipitation method. It was found that the specific surface area (SSA of both components is extremely different and equals 49.5 for TiO2 and 145.4 m2·g−1 for CdS. The comparison of particle size distribution and images obtained by means of transmission electron microscopy (TEM showed agglomeration of nanocomposites. X-ray diffraction (XRD patterns suggest that CdS crystallizes in a mixture of cubic and hexagonal phases. Optical reflectance spectra revealed a gradual shift of the fundamental absorption edge towards longer wavelengths with increasing CdS molar fraction, which indicates an extension of the absorption spectrum of TiO2. The photocatalytic activity in UV and UV-vis was tested with the use of methyl orange (MO. The Langmuir–Hinshelwood model described well the photodegradation process of MO. The results showed that the photocatalytic behaviour of the TiO2/CdS mixture is significantly better than that of pure nanopowders.

  7. Surface effect of natural zeolite (clinoptilolite) on the photocatalytic activity of TiO2

    International Nuclear Information System (INIS)

    Li Fangfei; Jiang Yinshan; Yu Lixin; Yang Zhengwen; Hou Tianyi; Sun Shenmei

    2005-01-01

    The surface interaction between TiO 2 and natural zeolite, clinoptilolite, has been investigated by means of transmission electron microscope (TEM), atom force microscope (AFM), X-ray diffractometer (XRD), diffuse reflectance infrared Fourier transform (DRIFT) and far Fourier transform infrared ray (FTIR) spectroscopy. And the photocatalytic degradation (PCD) rate of methyl orange (MO), a model of recalcitrant azo dye, in aqueous system has been measured to compare the photocatalytic activities of different photocatalysts. A model has been carried out to explain the incorporation between TiO 2 particles and natural zeolite. The results show that the TiO 2 particles loaded on zeolite are 50 nm or so, smaller than the pure one, and combine with zeolite via chemical force. Since the reserved adsorption ability and the existence of electron trapper, the TiO 2 -zeolite performed more efficient at low initial concentration and in the later period of PCD process, as compared with pure TiO 2 nanopowders

  8. Nanostructured Photocatalytic TiO2 Coating Deposited by Suspension Plasma Spraying with Different Injection Positions

    Science.gov (United States)

    Liu, Xuezhang; Wen, Kui; Deng, Chunming; Yang, Kun; Deng, Changguang; Liu, Min; Zhou, Kesong

    2018-02-01

    High plasma power is beneficial for the deposition efficiency and adhesive strength of suspension-sprayed photocatalytic TiO2 coatings, but it confronts two challenges: one is the reduced activity due to the critical phase transformation of anatase into rutile, and the other is fragmented droplets which cannot be easily injected into the plasma core. Here, TiO2 coatings were deposited at high plasma power and the position of suspension injection was varied with the guidance of numerical simulation. The simulation was based on a realistic three-dimensional time-dependent numerical model that included the inside and outside of torch regions. Scanning electron microscopy was performed to study the microstructure of the TiO2 coatings, whereas x-ray diffraction was adopted to analyze phase composition. Meanwhile, photocatalytic activities of the manufactured TiO2 coatings were evaluated by the degradation of an aqueous solution of methylene blue dye. Fragmented droplets were uniformly injected into the plasma jet, and the solidification pathway of melting particles was modified by varying the position of suspension injection. A nanostructured TiO2 coating with 93.9% anatase content was obtained at high plasma power (48.1 kW), and the adhesive coating bonding to stainless steel exhibited the desired photocatalytic activity.

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

    International Nuclear Information System (INIS)

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

    2008-01-01

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

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

    Science.gov (United States)

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

    2008-12-30

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

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  12. The effect of TiO2 nanocrystal shape on the electrical properties of poly(styrene-b-methyl methacrylate) block copolymer based nanocomposites for solar cell application

    International Nuclear Information System (INIS)

    Cano, Laida; Gutierrez, Junkal; Di Mauro, A. Evelyn; Curri, M. Lucia; Tercjak, Agnieszka

    2015-01-01

    Titanium dioxide (TiO 2 ) nanocrystals were synthesized into two shapes, namely spherical and rod-like and used for the fabrication of polystyrene-block-poly(methyl methacrylate) (PSMMA) block copolymer based nanocomposites, which were employed as the active top layer of electro-devices for solar cell application. Electro-devices were designed using nanocomposites with high TiO 2 nanocrystal contents (50-70 wt%) and for comparison as-synthesized TiO 2 nanospheres (TiO 2 NSs) and TiO 2 nanorods (TiO 2 NRs) were also used. The morphology of the electro-devices was studied by atomic force microscopy showing good nanocrystal dispersion. The electrical properties of the devices were investigated by PeakForce tunneling atomic force microscopy and Keithley semiconductor analyzer, which showed higher electrical current values for devices containing TiO 2 NRs in comparison to TiO 2 NSs. Remarkably, the influence of the PSMMA block copolymer on the improvement of the conductivity of the electro-devices was also assessed, demonstrating that the self-assembling ability of block copolymer can be beneficial to improve charge transfer in the fabricated electro-devices, thus representing relevant systems to be potentially developed for photovoltaic applications. Moreover, the absorbance of the prepared electro-devices in solar irradiation range was confirmed by UV–vis spectroscopy characterization.

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

    Science.gov (United States)

    Rashed, M. Nageeb; Eltaher, M. A.; Abdou, A. N. A.

    2017-12-01

    Nanocomposite TiO2/ASS (TiO2 nanoparticle coated sewage sludge-based activated carbon) was synthesized by the sol-gel method. The changes in surface properties of the TiO2/ASS nanocomposite were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and X-ray fluorescence. The prepared TiO2/ASS nanocomposite was applied for simultaneous removal of methyl orange dye (MO) and Cd2+ from bi-pollutant solution. The factors influencing photocatalysis (TiO2 : ASS ratios, initial pollutant concentrations, solution pH, nanocomposite dosage and UV irradiation time) were investigated. The results revealed that high removal efficiency of methyl orange dye (MO) and Cd2+ from bi-pollutant solution was achieved with TiO2/ASS at a ratio (1 : 2). The obtained results revealed that degradation of MO dye on the TiO2/ASS nanocomposite was facilitated by surface adsorption and photocatalytic processes. The coupled photocatalysis and adsorption shown by TiO2/ASS nanocomposite resulted in faster and higher degradation of MO as compared to MO removal by ASS adsorbent. The removal efficiency of MO by ASS adsorbent and TiO2/ASS (1 : 2) nanocomposite at optimum pH value 7 were 74.14 and 94.28%, respectively, while for Cd2+ it was more than 90%. The experimental results fitted well with the second-order kinetic reaction.

  14. Synthesis and characterization of Fe-doped TiO2 photocatalyst by the sol–gel method

    International Nuclear Information System (INIS)

    Luu, Cam Loc; Ho, Si Thoang; Nguyen, Quoc Tuan

    2010-01-01

    Thin layers of pure TiO 2 and TiO 2 doped by different amounts of Fe 2 O 3 have been prepared by the sol–gel method with tetraisopropyl orthotitanate and Fe(NO 3 ) 3 . Physico-chemical properties of catalysts were characterized by BET Adsorption, x-ray Diffraction (XRD), FE-SEM, as well as Raman and UV-Vis spectroscopy. The photocatalytic activity of the obtained materials was investigated in the reaction of complete oxidation of p-xylene in gas phase under the radiation of UV (λ=365 nm) and LED (λ=470 nm) lamps. It has been found that the particle size of all samples was distributed in the range 20–30 nm. The content of the rutile phase in Fe-doped TiO 2 samples varied in the range 6.8 to 41.8% depending on the Fe content. Iron oxide doped into TiO 2 enables the photon absorbing zone of TiO 2 to extend from UV towards visible waves as well as to reduce its band gap energy from 3.2 to 2.67 eV. Photocatalytic activities of the TiO 2 samples modified by Fe 3+ have been found to be higher than those of pure TiO 2 by about 2.5 times

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

    Directory of Open Access Journals (Sweden)

    Rebah Moussaoui

    2017-09-01

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

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

    Science.gov (United States)

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

    2018-06-01

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

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

    International Nuclear Information System (INIS)

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

    2010-01-01

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

  18. 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.

  19. TiO2 supported on rod-like mesoporous silica SBA-15: Preparation, characterization and photocatalytic behaviour

    International Nuclear Information System (INIS)

    Li, Yanjuan; Li, Nan; Tu, Jinchun; Li, Xiaotian; Wang, Beibei; Chi, Yue; Liu, Darui; Yang, Dianfan

    2011-01-01

    Highlights: ► Rod-like SBA-15 and normal SBA-15 were used to prepare TiO 2 /SBA-15 composites. ► TiO 2 /SBA-15 composites were studied as catalysts for methyl orange photodegradation. ► TiO 2 /Rod-SBA-15 exhibited higher photocatalytic activity than TiO 2 /Nor-SBA-15. ► The higher catalytic activity was a result of the controlled morphology of SBA-15. -- Abstract: TiO 2 nanoparticles have been successfully incorporated in the pores of mesoporous silica SBA-15 with different morphologies by a wet impregnation method. The composites were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), inductively coupled plasma (ICP) emission spectroscopy, transmission electron microscopy (TEM), N 2 -sorption and UV–Vis diffuse reflectance spectroscopy. The photodegradation of methyl orange (MO) was used to study their photocatalytic property. It is indicated that the morphology of SBA-15 had a great influence on the photocatalytic activity of the composites. When TiO 2 /SBA-15 composite was prepared by loading TiO 2 nanoparticles on uniform rod-like SBA-15 of 1 μm length, it showed higher photocatalytic degradation rate than that on less regular but much larger SBA-15 support. This difference was rationalized in terms of the homogeneously distributed and shorter channels of rod-like SBA-15, which favored mass transport and improved the efficient utilization of the pore surface.

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

    International Nuclear Information System (INIS)

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

    2008-01-01

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

  1. Effect of preparation conditions on the characteristics and photocatalytic activity of TiO2/purified diatomite composite photocatalysts

    International Nuclear Information System (INIS)

    Sun, Zhiming; Hu, Zhibo; Yan, Yang; Zheng, Shuilin

    2014-01-01

    Highlights: • TiO 2 /purified diatomite composites were synthesized under different conditions. • The optimum preparation conditions of composites were obtained. • The obtained photocatalyst showed good photocatalytic activity. • The dispersity and grain size of loaded TiO 2 NPs are the critical factors. - Abstract: TiO 2 /purified diatomite composite materials were prepared through a modified hydrolysis-deposition method under low temperature using titanium tetrachloride as precursor combined with a calcination crystallization process. The microstructure and crystalline phases of the obtained composites prepared under different preparation conditions were characterized by high resolution scanning electron microscope (SEM) and X-ray diffraction (XRD), respectively. The photocatalytic performance of TiO 2 /purified diatomite composites was evaluated by Rhodamine B as the target pollutant under UV irradiation, and the optimum preparation conditions of composites were obtained. The TiO 2 crystal form in composites prepared under optimum conditions was anatase, the grain size of which was 34.12 nm. The relationships between structure and property of composite materials were analyzed and discussed. It is indicated that the TiO 2 nanoparticles uniformly dispersed on the surface of diatoms, and the photocatalytic performance of the composite materials was mainly determined by the dispersity and grain size of loaded TiO 2 nanoparticles

  2. Photo catalytic degradation of nitrobenzene using nanocrystalline TiO2 photo catalyst doped with Zn ions

    International Nuclear Information System (INIS)

    Reynoso S, E. A.; Perez S, S.; Reyes C, A. P.; Castro R, C. L.; Felix N, R. M.; Lin H, S. W.; Paraguay D, F.; Alonso N, G.

    2013-01-01

    Photo catalysis is a method widely used in the degradation of organic pollutants of the environment. The development of new materials is very important to improve the photo catalytic properties and to find new applications for TiO 2 as a photo catalyst. In this article we reported the synthesis of a photo catalyst based on TiO 2 doped with Zn 2+ ions highly efficient in the degradation of nitrobenzene. The results of photo catalytic activity experiments showed that the Zn 2+ doped TiO 2 is more active that un-doped TiO 2 catalyst with an efficiency of 99% for the nitrobenzene degradation at 120 min with an apparent rate constant of 35 x 10 -3 min -1 . For the characterization of photo catalyst X-ray diffraction, transmission electron microscopy and Raman spectroscopy were used. (Author)

  3. Study on Gas Sensing Performance of TiO2 Screen Printed Thick Films

    Directory of Open Access Journals (Sweden)

    C. G. DIGHAVKAR

    2009-02-01

    Full Text Available Titanium dioxide (TiO2 thick films were prepared on alumina substrate by using screen printing technique. After preparation, the films were fired at temperature range 600 -1000 ºC for two hour. Morphological, compositional and structural properties of the film samples were performed by means of several techniques, including scanning electron microscopy (SEM, Energy dispersive spectroscopy (EDS, X-ray diffraction techniques. We explore the various gases to study the sensing performance of the TiO2 thick films. The maximum response was reported to film fired at 800 0C for LPG gas at 350 0C operating temperature.

  4. Defect types and room-temperature ferromagnetism in undoped rutile TiO2 single crystals

    Science.gov (United States)

    Li, Dong-Xiang; Qin, Xiu-Bo; Zheng, Li-Rong; Li, Yu-Xiao; Cao, Xing-Zhong; Li, Zhuo-Xin; Yang, Jing; Wang, Bao-Yi

    2013-03-01

    Room-temperature ferromagnetism has been experimentally observed in annealed rutile TiO2 single crystals when a magnetic field is applied parallel to the sample plane. By combining X-ray absorption near the edge structure spectrum and positron annihilation lifetime spectroscopy, Ti3+—VO defect complexes (or clusters) have been identified in annealed crystals at a high vacuum. We elucidate that the unpaired 3d electrons in Ti3+ ions provide the observed room-temperature ferromagnetism. In addition, excess oxygen ions in the TiO2 lattice could induce a number of Ti vacancies which obviously increase magnetic moments.

  5. Hydrothermal synthesis of Fe-doped TiO2 nanostructure photocatalyst

    International Nuclear Information System (INIS)

    Nguyen, Van Nghia; Nguyen, Ngoc Khoa Truong; Nguyen, Phi Hung

    2011-01-01

    Fe-doped TiO 2 catalyst was prepared by the hydrothermal method. The resulting nanopowders were characterized by x-ray diffraction, transmission electron microscopy and Raman and UV-visible spectroscopies. The photocatalytic activity of the Fe-doped TiO 2 was tested by decomposition of methylene orange with a concentration of 10 mg l −1 in aqueous solution. The obtained results showed that methylene orange was significantly degraded after irradiation for 90 min under a halogen lamp and sunlight. The doping effect on the photocatalytic activity of the iron-doped catalyst samples are discussed

  6. Structural and vibrational investigations of Nb-doped TiO2 thin films

    International Nuclear Information System (INIS)

    Uyanga, E.; Gibaud, A.; Daniel, P.; Sangaa, D.; Sevjidsuren, G.; Altantsog, P.; Beuvier, T.; Lee, Chih Hao; Balagurov, A.M.

    2014-01-01

    Highlights: • We studied the evolutions of structure for TiO 2 thin film as changes with Nb doping and temperatures. • Up to 800 °C, the grain size of Nb 0.1 Ti 0.9 O 2 is smaller than for pure TiO 2 because doped Nb hinders the growth of the TiO 2 grains. • There was no formation of the rutile phase at high temperature. • Nb doped TiO 2 films have high electron densities at 400–700 °C. • Nb dope extends the absorbance spectra of TiO 2 which leads to the band gap reduce. - Abstract: Acid-catalyzed sol–gel and spin-coating methods were used to prepare Nb-doped TiO 2 thin film. In this work, we studied the effect of niobium doping on the structure, surface, and absorption properties of TiO 2 by energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray reflectometry (XRR), X-ray photoelectron spectroscopy (XPS), Raman, and UV–vis absorption spectroscopy at various annealing temperatures. EDX spectra show that the Nb:Ti atomic ratios of the niobium-doped titania films are in good agreement with the nominal values (5 and 10%). XPS results suggest that charge compensation is achieved by the formation of Ti vacancies. Specific niobium phases are not observed, thus confirming that niobium is well incorporated into the titania crystal lattice. Thin films are amorphous at room temperature and the formation of anatase phase appeared at an annealing temperature close to 400 °C. The rutile phase was not observed even at 900 °C (XRD and Raman spectroscopy). Grain sizes and electron densities increased when the temperature was raised. Nb-doped films have higher electron densities and lower grain sizes due to niobium doping. Grain size inhibition can be explained by lattice stress induced by the incorporation of larger Nb 5+ ions into the lattice. The band gap energy of indirect transition of the TiO 2 thin films was calculated to be about 3.03 eV. After niobium doping, it decreased to 2.40 eV

  7. Defect types and room-temperature ferromagnetism in undoped rutile TiO2 single crystals

    International Nuclear Information System (INIS)

    Li Dong-Xiang; Cao Xing-Zhong; Li Zhuo-Xin; Yang Jing; Wang Bao-Yi; Qin Xiu-Bo; Zheng Li-Rong; Li Yu-Xiao

    2013-01-01

    Room-temperature ferromagnetism has been experimentally observed in annealed rutile TiO 2 single crystals when a magnetic field is applied parallel to the sample plane. By combining X-ray absorption near the edge structure spectrum and positron annihilation lifetime spectroscopy, Ti 3+ —V O defect complexes (or clusters) have been identified in annealed crystals at a high vacuum. We elucidate that the unpaired 3d electrons in Ti 3+ ions provide the observed room-temperature ferromagnetism. In addition, excess oxygen ions in the TiO 2 lattice could induce a number of Ti vacancies which obviously increase magnetic moments

  8. The TiO2 Refraction Film for CsI Scintillator

    OpenAIRE

    C. C. Chen; C. W. Hun; C. J. Wang; C. Y. Chen; J. S. Lin; K. J. Huang

    2015-01-01

    Cesium iodide (CsI) melt was injected into anodic aluminum oxide (AAO) template and was solidified to CsI column. The controllable AAO channel size (10~500 nm) can makes CsI column size from 10 to 500 nm in diameter. In order to have a shorter light irradiate from each singe CsI column top to bottom the AAO template was coated a TiO2 nano-film. The TiO2 film acts a refraction film and makes X-ray has a shorter irradiation path in the CsI crystal making a stronger the photo-electron signal. Wh...

  9. A chemical route to room-temperature synthesis of nanocrystalline TiO2 thin films

    International Nuclear Information System (INIS)

    Pathan, Habib M.; Kim, Woo Young; Jung, Kwang-Deog; Joo, Oh-Shim

    2005-01-01

    A lot of methods are developed for the deposition of TiO 2 thin films; however, in each of these methods as-deposited films are amorphous and need further heat treatment at high temperature. In the present article, a chemical bath deposition (CBD) method was used for the preparation of TiO 2 thin films. We investigated nanocrystalline TiO 2 thin films using CBD at room temperature onto glass and ITO coated glass substrate. The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM) techniques. The chemically synthesized films were nanocrystalline and composed of crystal grains of 2-3 nm

  10. Photocatalytic activity of TiO2 doped with boron and vanadium

    International Nuclear Information System (INIS)

    Bettinelli, M.; Dallacasa, V.; Falcomer, D.; Fornasiero, P.; Gombac, V.; Montini, T.; Romano, L.; Speghini, A.

    2007-01-01

    Boron (B)- and vanadium (V)-doped TiO 2 photocatalysts were synthesized using modified sol-gel reaction processes and characterized by X-ray diffraction (XRD), Raman spectroscopy and N 2 physisorption (BET). The photocatalytic activities were evaluated by monitoring the degradation of methylene blue (MB). The results showed that the materials possess high surface area. The addition of B favored the transformation of anatase to rutile, while in the presence of V, anatase was the only phase detected. The MB degradation on V-doped TiO 2 was significantly affected by the preparation method. In fact while the presence of V in the bulk did not influence strongly the photoreactivity under visible irradiation, an increase of surface V doping lead to improved photodegradation of MB. The degradation of MB dye indicated that the photocatalytic activities of TiO 2 increased as the boron doping increased, with high conversion efficiency for 9 mol% B doping

  11. Photocatalytic decomposition of diclofenac potassium using silver-modified TiO2 thin films

    International Nuclear Information System (INIS)

    Cavalheiro, A.A.; Bruno, J.C.; Saeki, M.J.; Valente, J.P.S.; Florentino, A.O.

    2008-01-01

    The effects of silver insertion on the TiO 2 photocatalytic activity for the degradation of diclofenac potassium were reported here. Techniques such as X-ray diffraction, scanning electron microscopy and UV-Vis spectroscopy were used to comprehend the relation between structure and properties of the silver-modified TiO 2 thin films obtained by the sol-gel method. The lattice parameters and the crystallinity of TiO 2 anatase phase were affected by inserted silver, and the film thickness increased about 4 nm for each 1 wt.% of silver inserted. The degradation of diclofenac potassium and by-products reached an efficiency of 4.6 mg C W -1 when the material was modified with silver. Although the first step of degradation involves only the photochemical process related to the loss of the chlorine and hydrogen atoms. This cyclization reaction leads to the formation of intermediate, which degradation is facilitated by the modified material

  12. Physics properties of TiO_2 films produced by dip-coating technique

    International Nuclear Information System (INIS)

    Teloeken, A.C.; Alves, A.K.; Berutti, F.A.; Tabarelli, A.; Bergmann, C.P.

    2014-01-01

    The use of titanium dioxide (TiO_2) as a photocatalyst to produce hydrogen has been of great interest because of their chemical stability, low cost and non-toxicity. TiO_2 occurs in three different crystal forms: rutile, anatase and brokita. Among these, the anatase phase generally exhibits the best photocatalytic behavior, while the rutile phase is the most stable. Among the various techniques of deposition, dip-coating technique produces films with good photocatalytic properties, using simple and inexpensive equipment. In this work TiO_2 films were obtained by dip-coating. The films were characterized using X-ray diffraction, scanning electron microscopy, profilometry, contact angle measurements and photocurrent. The microstructure and physical properties were evaluated in relation of the temperature and the addition of an additive. (author)

  13. The Influence of TiO2 Nanoparticles on LaFeO3/TiO2 Nanocomposites for Reduction of Aqueous Organic Dyes

    International Nuclear Information System (INIS)

    Afifah, N.; Saleh, R.

    2016-01-01

    A series of Lanthanum ferrite (LaFeO3) nanoparticles over titanium dioxide (TiO2) were synthesized using sol-gel method at room temperature by varying the loading of LaFeO3 on TiO2. The magnetic properties of samples were measured using vibrating sample magnetometer and photosonocatalytic activity towards the degradation of methylene blue under light (UV or visible) and ultrasound irradiation was also evaluated. The morphology and structure of the samples were characterized by field emission scanning electron microscope, energy dispersive analysis and X-ray diffraction. Furthermore the optical properties were also characterized by UV-visible diffuse reflectance. The experimental results showed that the prepared perovskites had sphere-like shape and strong visible light absorption. LaFeO3 demonstrated ferromagnetic properties and the magnetization decreased with the incorporation of TiO2 in the samples. However, the incorporation of TiO2 increased the photosonocatalytic activity and extended the photoresponding to UV light. (paper)

  14. Efectos de fotodegradación propiciados por recubrimientos de TiO2 y TiO2-SiO2 obtenidos por Sol-Gel

    Directory of Open Access Journals (Sweden)

    Rodriguez Paez, J. E.

    2008-10-01

    Full Text Available Photodegradation effect is widely used for water purification this contributes to preservation and protection of environment. Titanium oxide, (TiO2, is a compound that shows up this phenomenon. TiO2 is a semiconductor which may degradate pollutants through of a oxidation process. It permit the treatment of the residual water. It this work we has conformed coatings of TiO2 y TiO2-SiO2, utilized Sol-Gel method and investigated the degradation of the blue Methylene. For this, we introduced these coatings in the blue methylene solution which was illuminated with radiation of λ=365nm to activate its photocatilist properties. The structures of the coatings were characterized using Atomic Force Microscopy (AFM and X-ray Photoelectron Spectroscopy (XPS.El efecto de fotodegradación es ampliamente utilizado para la purificación del agua, acción que contribuye a la conservación y protección del medio ambiente; el óxido de titanio (TiO2 es uno de los semiconductores que pueden degradar contaminantes mediante procesos de oxidación, lo que lo hace apto para el tratamiento de aguas residuales. En este trabajo se conformaron recubrimientos de TiO2 y TiO2-SiO2, por el método Sol-Gel, y se estudio la degradación que experimentaba una solución de azul de metileno al introducirle estos recubrimientos e iluminarlos con una radiación de λ=365nm para activar su propiedad fotocatalítica. Los recubrimientos fueron caracterizados microestructuralmente utilizando Microscopía de Fuerza Atómica (MFA y Espectroscopía de Fotoelectrones de rayos X (XPS. Los resultados obtenidos de los ensayos de fotodegradación indican que los recubrimientos con una cantidad pequeña de silicio presentan un mayor efecto de fotodegradación indicando que el silicio puede generar puntos de anclaje que facilitan las reacciones de fotocatálisis. Por otro lado, la formación de centros activos, constituidos principalmente por carbono, también contribuyeron al desarrollo de estas

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

    Science.gov (United States)

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

    2018-02-01

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

  16. Facile synthesis of Ag nanoparticles supported on TiO2 inverse opal with enhanced visible-light photocatalytic activity

    International Nuclear Information System (INIS)

    Zhao Yongxun; Yang Beifang; Xu Jiao; Fu Zhengping; Wu Min; Li Feng

    2012-01-01

    TiO 2 inverse opal films loaded with silver nanoparticles (ATIO) were synthesized on glass substrates. TiO 2 inverse opal (TIO) films were prepared via a sol–gel process using self-assembly of SiO 2 colloidal crystal template and a facile wet chemical route featuring an AgNO 3 precursor solution to fabricate silver nanoparticles on the TIO films. The inverse opal structure and Ag deposition physically and chemically modify titania, respectively. The catalysts were characterized by Raman spectroscopy, field-emission scanning electron microscopy, high-resolution transmission electron microscopy (HRTEM), UV–vis absorption spectra, X-ray photoelectron spectroscopy and photoluminescence spectroscopy. The HRTEM results show that Ag nanoparticles measuring 5–10 nm were evenly distributed on TIO. Both the UV- and visible-light photocatalytic activities of the samples were evaluated by analyzing the degradation of methylene blue (MB) in aqueous solution. The results reveal that the apparent reaction rate constant (k app ) of MB degradation of the sample ATIO under UV-light irradiation is approximately 1.5 times that of the conventional Ag-loaded TiO 2 film (ATF) without an ordered porous structure at an AgNO 3 concentration of 5 mM in the precursor solution. At an AgNO 3 concentration of 10 mM, the sample exhibits a k app value approximately 4.2 times that of ATF under visible-light irradiation. This enhanced visible-light photocatalytic performance can be attributed to the synergistic effect of optimized Ag nanoparticle deposition and an ordered macroporous TIO structure. Repeated cycling tests revealed that the samples showed stable photocatalytic activity, even after six repeated cycles. - Highlights: ►TiO 2 inverse opal films loaded with silver nanoparticles were synthesized. ►Physical and chemical modifications of TiO 2 were achieved simultaneously. ►The catalysts exhibited enhanced visible-light photocatalytic activity. ►The mechanism for enhanced

  17. Preparation of TiO2 photocatalyst with the matrix of palm wood ( Arenga pinnata ) waste in the photodegradation of batik wastewater

    International Nuclear Information System (INIS)

    Kresnadipayana, Dian; Wahyuni, Endang Tri; Santosa, Sri Juari; Mudasir

    2017-01-01

    The study aimed to the preparation of TiO 2 photocatalyst with the matrix from palm wood waste whose has lignin and cellulose content. TiO 2 photocatalyst with the matrix from the wastewater of palm wood waste (TiO 2 /pww) was used as photocatalyst in photodegradation of batik wastewater. TiO 2 solid was dissolved in ethanol and aquadest, added with the powder of wood palm waste and stirred with a magnetic stirrer for 16 hours. Then separation was carried out using buchner and filtrate and residue were obtained. The filtrate was disposed and the residue was calcined with various temperatures for 3 hours. The temperatures in this research were 100 °C (TiO 2 /pww-100); 200°C (TiO 2 /pww-200); 300°C (TiO 2 /pww-300). Analysis and characterization of TiO 2 /wwp were conducted using X-ray diffraction (XRD) and spectrophotometer Fourier Transform Infra Red (FTIR) methods. Photocalalytic TiO 2 /wwp use the batch system in a reactor with UV light 40 watts, 220 volts and length wave 360 nm the plate magnetic stirrer. Liquid waste batik adds TiO 2 /wwp with time variation. At XRD analysis showed that the preparation of TiO 2 /pww could be done on the heating TiO 2 /pww temperature of 100°C and 200°C. At the temperature of 300°C, it was indicated that the lignocelluloses in palm wood waste were burned, meaning that few lignocelluloses remained. The result of FTIR analysis showed clearly that at the temperature of 300°C, a few spectrum of lignocelluloses remained in palm wood waste, while at a temperature of 100°C and 200°C, spectra of lignocelluloses of palm wood waste remained. The result of photocatalysis test indicated that TiO 2 /pww could reduce 40%, 72%, 81% and 64% COD for TiO 2 (control), TiO 2 /pww-100, TiO 2 /pww-200 and TiO 2 /pww-300, respectively. (paper)

  18. Process optimization of dye-sensitized solar cells using TiO2 ...

    Indian Academy of Sciences (India)

    2017-11-23

    Nov 23, 2017 ... TiO2 attached closely on the graphene flake is possible to ... spacer between the two electrodes of the cell. Iodide-based .... Doping of high concentration of .... [34] Huang Q, Tian S, Zeng D, Wang X, Song W, Li Y et al 2013.

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

    Indian Academy of Sciences (India)

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

  20. Photocatalytic oxidation of NOx gases using TiO2: a surface spectroscopic approach

    International Nuclear Information System (INIS)

    Dalton, J.S.; Janes, P.A.; Jones, N.G.; Nicholson, J.A.; Hallam, K.R.; Allen, G.C.

    2002-01-01

    X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy were used to study surface reactions between nitrogen oxides and TiO 2 on surfaces. - The bandgap of solid-state TiO 2 (3.2 eV) enables it to be a useful photocatalyst in the ultraviolet (λ 2 surface in the presence of sunlight therefore enables the removal of harmful NO x gases from the atmosphere by oxidation to nitrates. These properties, in addition to the whiteness, relative cheapness and non-toxicity, make TiO 2 ideal for the many de-NOX catalysts that are currently being commercially exploited both in the UK and Japan for concrete paving materials in inner cities. There is need, however, for further academic understanding of the surface reactions involved. Hence, we have used surface specific techniques, including X-ray photoelectron spectroscopy and Raman spectroscopy, to investigate the NO x adsorbate reaction at the TiO 2 substrate surface

  1. TiO2 aerogel–metal organic framework nanocomposite: a new class ...

    Indian Academy of Sciences (India)

    2018-02-05

    Feb 5, 2018 ... titanium dioxide in association with a monolayer of dye molecules is .... Zn–MOF has not affected the anatase phase formation of. TiO2 crystals ..... [15] Xin X, Scheiner M, Ye M and Lin Z 2011 Langmuir 27 14594. [16] Kim B ...

  2. Synthesis of nanocrystalline TiO 2 thin films by liquid phase ...

    Indian Academy of Sciences (India)

    A transparent, high purity titanium dioxide thin film composed of densely packed nanometer sized grains has been successfully deposited on a glass substrate at 30°C from an aqueous solution of TiO2–HF with the addition of boric acid as a scavenger by liquid phase deposition technique. From X-ray diffraction ...

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

    International Nuclear Information System (INIS)

    Tian Lihong; Ye Liqun; Deng Kejian; Zan Ling

    2011-01-01

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

  4. Realization of Colored Multicrystalline Silicon Solar Cells with SiO2/SiNx:H Double Layer Antireflection Coatings

    Directory of Open Access Journals (Sweden)

    Minghua Li

    2013-01-01

    Full Text Available We presented a method to use SiO2/SiNx:H double layer antireflection coatings (DARC on acid textures to fabricate colored multicrystalline silicon (mc-Si solar cells. Firstly, we modeled the perceived colors and short-circuit current density (Jsc as a function of SiNx:H thickness for single layer SiNx:H, and as a function of SiO2 thickness for the case of SiO2/SiNx:H (DARC with fixed SiNx:H (refractive index n=2.1 at 633 nm, and thickness = 80 nm. The simulation results show that it is possible to achieve various colors by adjusting the thickness of SiO2 to avoid significant optical losses. Therefore, we carried out the experiments by using electron beam (e-beam evaporation to deposit a layer of SiO2 over the standard SiNx:H for 156×156 mm2 mc-Si solar cells which were fabricated by a conventional process. Semisphere reflectivity over 300 nm to 1100 nm and I-V measurements were performed for grey yellow, purple, deep blue, and green cells. The efficiency of colored SiO2/SiNx:H DARC cells is comparable to that of standard SiNx:H light blue cells, which shows the potential of colored cells in industrial applications.

  5. Undoped TiO2 and nitrogen-doped TiO2 thin films deposited by atomic layer deposition on planar and architectured surfaces for photovoltaic applications

    International Nuclear Information System (INIS)

    Tian, Liang; Soum-Glaude, Adurey; Volpi, Fabien; Salvo, Luc; Berthomé, Grégory; Coindeau, Stéphane; Mantoux, Arnaud; Boichot, Raphaël; Lay, Sabine; Brizé, Virginie; Blanquet, Elisabeth; Giusti, Gaël; Bellet, Daniel

    2015-01-01

    Undoped and nitrogen doped TiO 2 thin films were deposited by atomic layer deposition on planar substrates. Deposition on 3D-architecture substrates made of metallic foams was also investigated to propose architectured photovoltaic stack fabrication. All the films were deposited at 265 °C and nitrogen incorporation was achieved by using titanium isopropoxide, NH 3 and/or N 2 O as precursors. The maximum nitrogen incorporation level obtained in this study was 2.9 at. %, resulting in films exhibiting a resistivity of 115 Ω cm (+/−10 Ω cm) combined with an average total transmittance of 60% in the 400–1000 nm wavelength range. Eventually, TiO 2 thin films were deposited on the 3D metallic foam template

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

    International Nuclear Information System (INIS)

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

    2015-01-01

    Graphical abstract: TiO 2 nanowire arrays with controlled morphology and density have been synthesized on Ti mesh substrates by hydrothermal approach for flexible dye-sensitized solar cells which showed well photovoltaic efficiency of 3.42%. - Highlights: • Flexible titanium mesh was first used for hydrothermal preparation of TiO 2 NWAs. • The formation mechanism of the TiO 2 nanostructures was discussed. • The density, average diameter, and morphology of TiO 2 NWAs can be controlled. • The effects of the sensitization temperature and time on the properties were studied. - Abstract: TiO 2 nanowire arrays (NWAs) with an average diameter of 80 nm have been successfully synthesized on titanium (Ti) mesh substrates via hydrothermal method. The effects of preparing conditions such as concentration of NaOH solution, reaction time, and hydrothermal temperature on the growth of TiO 2 nanoarrays and its related photovoltaic properties were systematically investigated by scanning electron microscopy, X-ray diffraction, and photovoltaic properties test. The growth mechanism of the Ti mesh-supported TiO 2 nanostructures was discussed in detail. Moreover, a parametric study was performed to determine the optimized temperature and time of the dye sensitized process for the flexible dye-sensitized solar cell (DSSC). It is demonstrated that hydrothermal parameters had obvious influence on the morphology and growth density of the as-prepared TiO 2 nanoarrays. In addition, the performance of the flexible DSSC depended strongly on the sensitization temperature and time. By utilizing Ti mesh-supported TiO 2 NWAs (with a length of about 14 μm) as a photoanode, the flexible DSSC with a short circuit current density of 10.49 mA cm −2 , an open-circuit voltage of 0.69 V, and an overall power conversion efficiency of 3.42% was achieved

  7. Incorporation of TiO2 nanotubes in a polycrystalline zirconia: Synthesis of nanotubes, surface characterization, and bond strength.

    Science.gov (United States)

    Dos Santos, Angélica Feltrin; Sandes de Lucena, Fernanda; Sanches Borges, Ana Flávia; Lisboa-Filho, Paulo Noronha; Furuse, Adilson Yoshio

    2018-04-05

    Despite numerous advantages such as high strength, the bond of yttria-stabilized zirconia polycrystal (Y-TZP) to tooth structure requires improvement. The purpose of this in vitro study was to evaluate the incorporation of TiO 2 nanotubes into zirconia surfaces and the bond strength of resin cement to the modified ceramic. TiO 2 nanotubes were produced by alkaline synthesis, mixed with isopropyl alcohol (50 wt%) and applied on presintered zirconia disks. The ceramics were sintered, and the surfaces were characterized by confocal laser microscopy, scanning electron microscopy (SEM), and energy-dispersive x-ray spectroscopy (EDS) analysis. For bond strength, the following 6 groups (n=16) were evaluated: without TiO 2 and Single Bond Universal; with TiO 2 nanotubes and Single Bond Universal; without TiO 2 nanotubes and Z-prime; with TiO 2 nanotubes and Z-prime; without TiO 2 and Signum Zirconia Bond; with TiO 2 and Signum Zirconia Bond. After sintering, resin cement cylinders, diameter of 1.40 mm and 1 mm in height, were prepared and polymerized for 20 seconds. Specimens were stored in water at 37°C for 30 days and submitted to a shear test. Data were analyzed by 2-way ANOVA and Tukey honest significant difference (α=.05) tests. EDS analysis confirmed that nanoagglomerates were composed of TiO 2 . The shear bond strength showed statistically significant differences among bonding agents (P<.001). No significant differences were found with the application of nanotubes, regardless of the group analyzed (P=.682). The interaction among the bonding agent factors and addition of nanotubes was significant (P=.025). Nanotubes can be incorporated into zirconia surfaces. However, this incorporation did not improve bond strength. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  8. Solution-Processed Ultrathin TiO2 Compact Layer Hybridized with Mesoporous TiO2 for High-Performance Perovskite Solar Cells.

    Science.gov (United States)

    Jeong, Inyoung; Park, Yun Hee; Bae, Seunghwan; Park, Minwoo; Jeong, Hansol; Lee, Phillip; Ko, Min Jae

    2017-10-25

    The electron transport layer (ETL) is a key component of perovskite solar cells (PSCs) and must provide efficient electron extraction and collection while minimizing the charge recombination at interfaces in order to ensure high performance. Conventional bilayered TiO 2 ETLs fabricated by depositing compact TiO 2 (c-TiO 2 ) and mesoporous TiO 2 (mp-TiO 2 ) in sequence exhibit resistive losses due to the contact resistance at the c-TiO 2 /mp-TiO 2 interface and the series resistance arising from the intrinsically low conductivity of TiO 2 . Herein, to minimize such resistive losses, we developed a novel ETL consisting of an ultrathin c-TiO 2 layer hybridized with mp-TiO 2 , which is fabricated by performing one-step spin-coating of a mp-TiO 2 solution containing a small amount of titanium diisopropoxide bis(acetylacetonate) (TAA). By using electron microscopies and elemental mapping analysis, we establish that the optimal concentration of TAA produces an ultrathin blocking layer with a thickness of ∼3 nm and ensures that the mp-TiO 2 layer has a suitable porosity for efficient perovskite infiltration. We compare PSCs based on mesoscopic ETLs with and without compact layers to determine the role of the hole-blocking layer in their performances. The hybrid ETLs exhibit enhanced electron extraction and reduced charge recombination, resulting in better photovoltaic performances and reduced hysteresis of PSCs compared to those with conventional bilayered ETLs.

  9. Photoinduced Glycerol Oxidation over Plasmonic Au and AuM (M = Pt, Pd and Bi) Nanoparticle-Decorated TiO2 Photocatalysts

    Science.gov (United States)

    Jedsukontorn, Trin; Saito, Nagahiro; Hunsom, Mali

    2018-01-01

    In this study, sol-immobilization was used to prepare gold nanoparticle (Au NP)-decorated titanium dioxide (TiO2) photocatalysts at different Au weight % (wt. %) loading (Aux/TiO2, where x is the Au wt. %) and Au–M NP-decorated TiO2 photocatalysts (Au3M3/TiO2), where M is bismuth (Bi), platinum (Pt) or palladium (Pd) at 3 wt. %. The Aux/TiO2 photocatalysts exhibited a stronger visible light absorption than the parent TiO2 due to the localized surface plasmon resonance effect. Increasing the Au content from 1 wt. % to 7 wt. % led to increased visible light absorption due to the increasing presence of defective structures that were capable of enhancing the photocatalytic activity of the as-prepared catalyst. The addition of Pt and Pd coupled with the Au3/TiO2 to form Au3M3/TiO2 improved the photocatalytic activity of the Au3/TiO2 photocatalyst by maximizing their light-absorption property. The Au3/TiO2, Au3Pt3/TiO2 and Au3Pd3/TiO2 photocatalysts promoted the formation of glyceraldehyde from glycerol as the principle product, while Au3Bi3/TiO2 facilitated glycolaldehyde formation as the major product. Among all the prepared photocatalysts, Au3Pd3/TiO2 exhibited the highest photocatalytic activity with a 98.75% glycerol conversion at 24 h of reaction time. PMID:29690645

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

    International Nuclear Information System (INIS)

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

    2014-01-01

    The aim of the present study is to synthesize TiO 2 beads for urease immobilization. Two different strategies were used to immobilize the urease on TiO 2 beads. In the first method (A), urease enzyme was immobilized onto TiO 2 beads by adsorption and then crosslinking. In the second method (B), TiO 2 beads were coated with chitosan-urease mixture. To determine optimum conditions of immobilization, different parameters were investigated. The parameters of optimization were initial enzyme concentration (0.5; 1; 1.5; 2 mg/ml), alginate concentration (1; 2; 3%), glutaraldehyde concentration (1; 2; 3% v/v) and chitosan concentration (2; 3; 4 mg/ml). The optimum enzyme concentrations were determined as 1.5 mg/ml for A and 1.0 mg/ml for B. The other optimum conditions were found 2.0% (w/v) for alginate concentration (both A and B); 3.0 mg/ml for chitosan concentration (B) and 2.0% (v/v) for glutaraldehyde concentration (A). The optimum temperature (20-60 °C), optimum pH (3.0-10.0), kinetic parameters, thermal stability (4–70 °C), pH stability (4.0-9.0), operational stability (0-230 min) and reusability (20 times) were investigated for characterization. The optimum temperatures were 30 °C (A), 40 °C (B) and 35 °C (soluble). The temperature profiles of the immobilized ureases were spread over a large area. The optimum pH values for the soluble urease and immobilized urease prepared by using methods (A) and (B) were found to be 7.5, 7.0, 7.0, respectively. The thermal stabilities of immobilized enzyme sets were studied and they maintained 50% activity at 65 °C. However, at this temperature free urease protected only 15% activity. - Highlights: • TiO 2 and TiO 2 -chitosan beads for urease immobilization have been prepared and characterized. • The beads used in this work are good matrices for the immobilization of urease. • The immobilized urease was shown to have good properties and stabilities (pH and thermal stability, operational stability). • The 50% activity was protected after 11 cycles for method A and 16 cycles for method B

  11. 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.

  12. Low-temperature preparation of rutile-type TiO2 thin films for optical coatings by aluminum doping

    Science.gov (United States)

    Ishii, Akihiro; Kobayashi, Kosei; Oikawa, Itaru; Kamegawa, Atsunori; Imura, Masaaki; Kanai, Toshimasa; Takamura, Hitoshi

    2017-08-01

    A rutile-type TiO2 thin film with a high refractive index (n), a low extinction coefficient (k) and small surface roughness (Ra) is required for use in a variety of optical coatings to improve the controllability of the reflection spectrum. In this study, Al-doped TiO2 thin films were prepared by pulsed laser deposition, and the effects of Al doping on their phases, optical properties, surface roughness and nanoscale microstructure, including Al distribution, were investigated. By doping 5 and 10 mol%Al, rutile-type TiO2 was successfully prepared under a PO2 of 0.5 Pa at 350-600 °C. The nanoscale phase separation in the Al-doped TiO2 thin films plays an important role in the formation of the rutile phase. The 10 mol%Al-doped rutile-type TiO2 thin film deposited at 350 °C showed excellent optical properties of n ≈ 3.05, k ≈ 0.01 (at λ = 400 nm) and negligible surface roughness, at Ra ≈ 0.8 nm. The advantages of the superior optical properties and small surface roughness of the 10 mol%Al-doped TiO2 thin film were confirmed by fabricating a ten-layered dielectric mirror.

  13. Ultrasonic Spray-Coating of Large-Scale TiO2 Compact Layer for Efficient Flexible Perovskite Solar Cells

    Directory of Open Access Journals (Sweden)

    Peng Zhou

    2017-02-01

    Full Text Available Flexible electronics have attracted great interest in applications for the wearable devices. Flexible solar cells can be integrated into the flexible electronics as the power source for the wearable devices. In this work, an ultrasonic spray-coating method was employed to deposit TiO2 nanoparticles on polymer substrates for the fabrication of flexible perovskite solar cells (PSCs. Pre-synthesized TiO2 nanoparticles were first dispersed in ethanol to prepare the precursor solutions with different concentrations (0.5 mg/mL, 1.0 mg/mL, 2.0 mg/mL and then sprayed onto the conductive substrates to produce compact TiO2 films with different thicknesses (from 30 nm to 150 nm. The effect of the different drying processes on the quality of the compact TiO2 film was studied. In order to further improve the film quality, titanium diisopropoxide bis(acetylacetonate (TAA was added into the TiO2-ethanol solution at a mole ratio of 1.0 mol % with respect to the TiO2 content. The final prepared PSC devices showed a power conversion efficiency (PCE of 14.32% based on the indium doped tin oxide coated glass (ITO-glass substrate and 10.87% on the indium doped tin oxide coated polyethylene naphthalate (ITO-PEN flexible substrate.

  14. Rapid photo-degradation of 2-chlorophenol under visible light irradiation using cobalt oxide-loaded TiO2/reduced graphene oxide nanocomposite from aqueous media.

    Science.gov (United States)

    Sharma, Ajit; Lee, Byeong-Kyu

    2016-01-01

    The photocatalytic removal of 2-chlorophenol (2-CP) from water environment was investigated by TiO2-RGO-CoO. Cobalt oxide-loaded TiO2 (TiO2-CoO) supported with reduced graphene oxide (RGO) was synthesized using a sol-gel method and then annealed at 500 °C for 5 min. The material characteristics were analyzed by UV-Vis analysis, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy. Incorporation of cobalt oxide and RGO into the TiO2 system (TiO2-RGO-CoO) lowered the band gap energy to 2.83 eV, which greatly enhanced the visible light absorption. The TiO2-RGO-CoO photocatalyst showed complete removal of 20 mg/L 2-CP within 8 h with the addition of 0.01% H2O2 under 100 W visible light irradiation. The photo-degradation efficiency of 2-CP (10 mg/L) was 35.2, 48.9, 58.9 and 98.2% for TiO2, TiO2-RGO, TiO2-CoO and TiO2-RGO-CoO, respectively, in the presence of visible light irradiation at solution pH of 6.0. The TiO2-RGO-CoO photocatalyst retained its high removal efficiency even after five photocatalytic cycles. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Improved performance of dye-sensitized solar cell based on TiO_2 photoanode with FTO glass and film both treated by TiCl_4

    International Nuclear Information System (INIS)

    Li, Jinlun; Zhang, Haiyan; Wang, Wenguang; Qian, Yannan; Li, Zhenghui

    2016-01-01

    The dye-sensitized solar cell (DSSC) based on TiO_2 photoanode with FTO glass and TiO_2 film co-treated by TiCl_4 were fabricated. The effects of TiCl_4 treatment on the photovoltaic performance of the DSSCs were investigated. TiCl_4 treatment of the FTO glass resulted in the formation of a compact TiO_2 thin layer on its surface, which could increase the electron collection efficiency. Meanwhile, TiCl_4 treatment of the TiO_2 film could fill gaps between nanoparticles in the TiO_2 film, leading to better electron transfer. These advantages make the DSSC exhibit a highest conversion efficiency of 3.34% under a simulated solar irradiation with an intensity of 100 mW/cm"2 (1 sun), increased by 38% compared with that of the untreated DSSC.

  16. TiO2 Nanorods Decorated with Pd Nanoparticles for Enhanced Liquefied Petroleum Gas Sensing Performance.

    Science.gov (United States)

    Dhawale, Dattatray S; Gujar, Tanaji P; Lokhande, Chandrakant D

    2017-08-15

    Development of highly sensitive and selective semiconductor-based metal oxide sensor devices to detect toxic, explosive, flammable, and pollutant gases is still a challenging research topic. In the present work, we systematically enhanced the liquefied petroleum gas (LPG) sensing performance of chemical bath deposited TiO 2 nanorods by decorating Pd nanoparticle catalyst. Surface morphology with elemental mapping, crystal structure, composition and oxidation states, and surface area measurements of pristine TiO 2 and Pd:TiO 2 nanorods was examined by high resolution transmission electron microscopy with energy-dispersive X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and nitrogen adsorption-desorption characterization techniques. LPG sensing performance of pristine TiO 2 and Pd:TiO 2 nanorods was investigated in different LPG concentration and operating temperature ranges. The LPG response of 21% for pristine TiO 2 nanorods is enhanced to 49% after Pd catalyst decoration with reasonably fast response and recovery times. Further, the sensor exhibited long-term stability, which could be due to the strong metal support (Pd:TiO 2 ) interaction and catalytic properties offered by the Pd nanoparticle catalyst. The work described herein demonstrates a general and scalable approach that provides a promising route for rational design of variety of sensor devices for LPG detection.

  17. Completely oriented anatase TiO2 nanoarrays: topotactic growth and orientation-related efficient photocatalysis

    Science.gov (United States)

    Yang, Jingling; Wu, Qili; He, Shiman; Yan, Jing; Shi, Jianying; Chen, Jian; Wu, Mingmei; Yang, Xianfeng

    2015-08-01

    A TiO2 film has been facilely grown on a Ti foil via a general and simple acid vapor oxidation (AVO) strategy. Based on detailed characterization by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), we found that the TiO2 film was composed of anatase nanoarrays highly oriented along their direction, resulting in a large exposed {001} top surface on the film. The growth mechanism based on a topotactic transformation was proposed according to a careful study of time-dependent experimental results. Resulting from the evaluation of photocatalytic performance compared with a commercial TiO2 photocatalyst (Degussa P25), the as-prepared oriented anatase TiO2 film showed higher efficiency for degradation of atrazine and acid orange II (AOII). The performance of photocatalysis is highly relevant to the preferential orientation. The efficient photocatalysis could be attributed to the highly reactive {001} facets on the anatase nanoarrays with super-hydrophilicity.A TiO2 film has been facilely grown on a Ti foil via a general and simple acid vapor oxidation (AVO) strategy. Based on detailed characterization by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), we found that the TiO2 film was composed of anatase nanoarrays highly oriented along their direction, resulting in a large exposed {001} top surface on the film. The growth mechanism based on a topotactic transformation was proposed according to a careful study of time-dependent experimental results. Resulting from the evaluation of photocatalytic performance compared with a commercial TiO2 photocatalyst (Degussa P25), the as-prepared oriented anatase TiO2 film showed higher efficiency for degradation of atrazine and acid orange II (AOII). The performance of photocatalysis is highly relevant to the preferential orientation. The efficient photocatalysis could be attributed to the highly reactive {001

  18. Influence of anodization parameters on the morphology of TiO 2 nanotube arrays

    Science.gov (United States)

    Omidvar, Hamid; Goodarzi, Saba; Seif, Ahmad; Azadmehr, Amir R.

    2011-07-01

    TiO 2 nanotube arrays can be fabricated by electrochemical anodization in organic and inorganic electrolytes. Morphology of these nanotube arrays changes when anodization parameters such as applied voltage, type of electrolyte, time and temperature are varied. Nanotube arrays fabricated by anodization of commercial titanium in electrolytes containing NH 4F solution and either sulfuric or phosphoric acid were studied at room temperature; time of anodization was kept constant. Applied voltage, fluoride ion concentration, and acid concentrations were varied and their influences on TiO 2 nanotubes were investigated. The current density of anodizing was recorded by computer controlled digital multimeter. The surface morphology (top-view) of nanotube arrays were observed by SEM. The nanotube arrays in this study have inner diameters in range of 40-80 nm.

  19. XPS-UPS, ISS characterization studies and the effect of Pt and K addition on the catalytic properties of MoO2-x(OH)y deposited on TiO2

    International Nuclear Information System (INIS)

    Al-Kandari, H.; Mohamed, A.M.; Al-Kharafi, F.; Katrib, A.

    2011-01-01

    Highlights: → Surface electronic structure-catalytic activity correlation is presented in this research work. → In situ characterization by XPS-UPS and ISS techniques were employed at the same experimental conditions applied for catalytic reactions. → Catalytic reactions of Mo deposited on titanium oxide for the isomerization and hydrogenation reactions using 1-hexene and n-hexane were studied. → The bifunctional properties of the molybdenum dioxide phase were modified by the addition of potassium. - Abstract: Characterization by XPS-UPS, ISS surface techniques of MoO 3 /TiO 2 catalysts before and after addition of Pt (PtMo) 2.5% by weight of MoO 3 and potassium (KMo) enabled to identify different chemical species present on the outermost surface layer at different reduction temperatures. Catalytic activities of these systems using 1-hexene and n-hexane reactants were studied. Correlation between catalytic activity and surface electronic structure enabled us to identify the chemical species, active site(s), responsible for specific catalytic reaction(s).

  20. Electrical properties of TiO2/SEO nanocomposites: From macro to nano

    International Nuclear Information System (INIS)

    Gutierrez, Junkal; Tercjak, Agnieszka; Martin, Loli; Mondragon, Inaki

    2011-01-01

    Graphical abstract: Display Omitted Highlights: → Three electro-devices were fabricated based on TiO 2 -SEO hybrid nanocomposites. → TUNA-current maps determine local conductivity variations at the nanoscale level. → Semiconductor analyzer allows to calculate conductivity values of investigated samples. → ITO/1:PEDOT-PSS/1:TiO 2 -SEO system show the highest conductivity value, 0.16 S/cm. - Abstract: Tunneling atomic force microscopy (TUNA) was successfully used to confirm that electro-devices based on TiO 2 -SEO nanocomposites can find possible application in solar power conversion field. Investigated electro-devices show different current flow depending on the layer combination. The highest capacity was shown by the electro-devices with a PEDOT-PSS layer on the top, being the average current values ∼200 pA at 10 V applied voltage. The conductivity value measured by Keithley indicated that the system ITO/1:PEDOT-PSS/1:TiO 2 -SEO electro-device shows the highest conductivity level, 0.16 S/cm. Thus, these systems have high potential to find application as solar cell devices.