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1.
A novel preparation method to synthesize TiO2/SnO2 nanocrystalline sol under mild conditions was presented. Ti(OC4H9)4 used as a precursor was hydrolyzed in the rutile SnO2 nanocrystalline sol, and in-situ formed TiO2/SnO2 nanocrystalline sol. The crystal structure, morphology and photocatalysis performance of samples were investigated. The results show that the additional rutile SnO2 nano grains serve as heterogeneous crystal nucleus and exhibite the inducing effect on TiO2 grains growth, thus leading to the changes in crystalline phase and particle morphology. In addition, the photoluminescence (PL) spectra analysis indicates that TiO2/SnO2 composite structure induces a better charge separation, and thus the photocatalytic activity of TiO2/SnO2 sol is increased significantly compared with TiO2 sol. 相似文献
2.
Yu-gui Tao Yan-qiu Xu Jun Pan Hao Gu Chang-yun Qin Peng Zhou 《Materials Science and Engineering: B》2012,177(18):1664-1671
Flower-like anatase TiO2 hierarchical spheres assembled by nanosheets were synthesized by glycine assistant via a simple hydrothermal approach and after-annealing process. These flower-like spheres are about 2 μm in diameter with sheet thickness about 20 nm. Results showed reaction time, temperature, solution pH and glycine dosage all played an important role in control of shape and size of the as-synthesized TiO2 nanocrystals. The photocatalytic activity of this nano-TiO2 was evaluated by the photocatalytic oxidation decomposition of methyl orange under sunlight illumination in the presence of hydrogen peroxide (H2O2). The photocatalytic activity of the obtained TiO2 was higher than that of commercial TiO2. 相似文献
3.
Choong-Soo ChiJinwook Choi Yongsoo JeongOh Yeon Lee Han-Jun Oh 《Thin solid films》2011,519(15):4676-4680
Micro-arc oxidation method is a useful process for mesoporous titanium dioxide films. In order to improve the photocatalytic activity of the TiO2 film, N-Eu co-doped titania catalyst was synthesized by micro-arc oxidation in the H2SO4/Eu(NO3)3 mixture solution.The specific surface area and the roughness of the anodic titania film fabricated in the H2SO4/Eu(NO3)3 electrolyte, were increased compared to that of the anodic TiO2 film prepared in H2SO4 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 TiO2 film significantly enhanced the photocatalytic activity for dye degradation. After dye decomposition test for 3 h, dye removal rates for the anodic TiO2 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 TiO2 band gap by N and Eu co-doping. 相似文献
4.
In the present study the intestine-like binary SnO2/TiO2 hollow nanostructures are one-pot synthesized in aqueous phase at room temperature via a colloid seeded deposition process in which the intestine-like hollow SnO2 spheres and Ti(SO4)2 are used as colloid seeds and Ti-source, respectively. The novel core (SnO2 hollow sphere)-shell (TiO2) nanostructures possess a large surface area of 122 m2/g (calcined at 350 °C) and a high exposure of TiO2 surface. The structural change of TiO2 shell at different temperatures was investigated by means of X-ray diffraction and Raman spectroscopy. It was observed that the rutile TiO2 could form even at room temperature due to the presence of SnO2 core and the unique core-shell interaction. 相似文献
5.
Catalytic photodegradation of organic contaminants by means of UV light has been demonstrated for gas sensors based on composites of TiO2-SnO2. Thin film resistive-type gas sensors of TiO2-SnO2 have been deposited at 350 °C by RF sputtering from a Ti-SnO2 target with varying surface ratio of SnO2/Ti. Photodegradation experiments of bromothymol blue by UV light have been performed by means of the optical spectrophotometry over the wavelength range extending from 300 nm to 600 nm. The influence of the UV illumination on the sensor response to 100-20,000 ppm of H2 has been investigated in situ on motor oil contaminated sensors. It has been found that sequential exposures to UV light lead to a partial recovery of the sensor signal to hydrogen. 相似文献
6.
Mesoporous TiO2 thin films were prepared by hydrothermal-oxidation of titanium metal thin films, which were obtained by DC magnetron sputtering technique. Gold nanoparticles, which were prepared by reduction of HAuCl4, were embedded into the holes of the mesoporous TiO2 films by capillary method followed by annealing in air up to 400 °C. The size of pore of TiO2 films is about 100 nm and that of Au nanoparticles is about 10 nm in average. The morphology of the films was analyzed by field emission scanning electron microscope (FE-SEM) and scanning probe microscopes (SPMs). Subsequently, the photocatalytic performances of the obtained nanosystems in the decomposition of methylene blue solution are discussed. The obtained results show that the dispersion of Au nanoparticles on the mesoporous TiO2 matrix will help enhancing the photocatalytic activity with respect to pure TiO2 under visible light irradiation. 相似文献
7.
Jing Yang 《Thin solid films》2008,516(8):1736-1742
To use solar irradiation or interior lighting efficiently, we sought a photocatalyst with high reactivity under visible light. Nitrogen and carbon doping TiO2 films were obtained by heating a TiO2 gel in an ionized N2 gas. The as-synthesized TiO2−x−yNxCy films have shown an improvement over titanium dioxide in optical absorption and photocatalytic activity such as photodegradation of methyl orange under visible light. The process of the oxygen atom substituted by nitrogen and carbon was discussed. Oxygen vacancy induced by the formation of Ti3+ species and nitrogen and carbon doped into substitution sites of TiO2 have been proven to be indispensable for the enhance of photocatalytic activity, as assessed by UV-Vis Spectroscopy and X-ray photoemission spectroscopy. 相似文献
8.
Synthesis of highly-active single-crystalline TiO2 nanorods and its application in environmental photocatalysis 总被引:1,自引:0,他引:1
Hoda S. Hafez 《Materials Letters》2009,63(17):1471-1474
Highly-active anatase TiO2 nanorods have been successfully synthesized via a simple two-step method, hydrothermal treatment of anatase/rutile titanium dioxide nanoparticle powder in a composite-hydroxide eutectic system of 1:1 M KOH/NaOH, followed by acid post-treatment. The morphology and crystalline structure of the obtained nanorods were characterized using XRD, TEM, SEM/EDX and BET surface area analyzer. The obtained TiO2 nanorods have a good crystallinity and a size distribution (about 4-16 nm); with the dimensions of 200-300 nm length and of 30-50 nm diameter. Compared with its precursor anatase/rutile TiO2 nanoparticles and the titanate nanotubes, the pure anatase TiO2 nanorods have a large specific surface area with a mesoporous structure. The photocatalytic performance of the prepared nanorods was tested in the degradation of the commercial Cibacrown Red (FN-R) textile dye, under UV irradiation. Single-crystalline anatase TiO2 nanorods are more efficient for the dye removal. 相似文献
9.
Photocatalytic degradation of gaseous benzene over TiO2/Sr2CeO4: kinetic model and degradation mechanisms 总被引:1,自引:0,他引:1
Photocatalytic oxidation of benzene in air was carried out over TiO2/Sr2CeO4 catalysts. The prepared photocatalyst was characterized by SBET, UV-vis diffuse reflectance and XPS. TiO2/Sr2CeO4 absorbs much more visible light than TiO2 in the visible light region. The XPS spectrum shows that the binding energy value of Ti 2p3/2 transfers to a lower value. The main purpose was to investigate the kinetic model and degradation mechanisms. The kinetic data matched well with the Langmuir-Hinshelwood (L-H) kinetic model with the limiting rate constant and the adsorption constant in this case were 0.0064 mg l-1 min-1 and 9.2078 l mg-1, respectively. No gas-phase intermediates were detected by direct GC/FID analysis under the conditions despite the high benzene concentration. Ethyl acetate and (3-methyl-oxiran-2-yl)-methanol were two major identified intermediates which were accompanied by butylated hydroxytoluene, 2,6-bis(1,1-dimethylethyl)-4,4-dimethylycyclohe, 2,5-cyclohexadiene-1,4,dione,2,6-bis(1,1-dim). It is plausible that at least one of these less-reactive intermediates caused the deactivation of the photocatalyst. Finally, the photocatalytic oxidation mechanisms were speculated. 相似文献
10.
In this study, we report that nitrogen doped TiO2 could be achieved via thermal treatment of Degussa P25 TiO2 in NO atmosphere directly (P25-NO). The samples were characterized with XRD, XPS, and FT-IR. The characterization results suggested that nitrogen species were interstitially doped in P25-NO during the NO thermal treatment process. In comparison with P25, the P25-NO exhibited significantly enhanced photocatalytic activities under visible light irradiation (λ > 420 nm) for gaseous NO removal. On the basis of electronic band structure theory, we proposed a possible mechanism for the enhanced visible light driven photocatalytic oxidation process over the interstitial N doping P25-NO samples. This work could not only deepen understanding of the enhanced photoactivity originated from interstitial N doping in TiO2, but also provide a facile route to prepare nitrogen doped TiO2 for environmental and energy applications. 相似文献
11.
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. 15 wt% 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 80% mineralization occurred in 5 h. A plausible mechanism is proposed based on the intermediates identified by liquid chromatography–mass spectroscopy (LC–MS). 相似文献
12.
TiO2/SiOx/TiOx multi-layers on quartz glass were prepared by electron-beam evaporation method and their structural and photocatalytic properties were investigated. The photocatalytic activity of the TiO2/SiOx/TiOx multi-layer was evaluated by the photodecomposition of methylene blue in aqueous solution. As the thickness of the SiOx inter-layer increased, the surface roughness of the TiO2/SiOx/TiOx multi-layer increased but the anatase crystallite size decreased. The TiO2/SiOx(80 nm)/TiOx multi-layer exhibited excellent photocatalytic activity resulting from higher surface roughness and more trap levels in the SiOx(80 nm) inter-layer. 相似文献
13.
Stefan Wiechmann 《Thin solid films》2009,517(24):6847-1504
The direct measurement of the thermo-optic coefficients of aluminium oxide, tantalum pentoxide and titanium dioxide thin films is presented. Using ellipsometry on monolithically integrated permutations of the layers of silicon, silicon dioxide and the material under test, allows the direct measurement of the overall thermo-optic coefficient accounting for thermally induced changes in the dielectric permittivity and density of the materials as well as the elasto-optic effect due to the non-matching thermal expansion coefficients of the different materials. 相似文献
14.
Fe-C-TiO(2) photocatalysts were prepared by mechanical mixing of commercial anatase TiO(2) precursor with FeC(2)O(4) and heating at 500-800 degrees C under argon flow. These photocatalysts were tested for dyes decomposition: Methylene Blue (MB), Reactive Black (RB) and Acid Red (AR). The preliminary adsorption of dyes on the photocatalysts surface was performed. Modification of anatase by FeC(2)O(4) caused reducing of zeta potential of the photocatalyst surface from +12 to -7mV and decreasing of their adsorption ability towards RB and AR, which were negatively charged, -46.8 and -39.7, respectively. Therefore, unmodified TiO(2) showed the highest degree of RB and AR decompositions in the combination of dyes adsorption and UV irradiation. Methylene Blue, which had zeta potential of +4.3 in the aqueous solution was poorly adsorbed on all the tested photocatalysts and also slowly decomposed under UV irradiation. The high rate of dyes decomposition was noted on Fe-C-TiO(2) photocatalysts under UV irradiation with addition of H(2)O(2). It was observed, that at lower temperatures of heat treatment such as 500 degrees C higher content of carbon is remained in the sample, blocking the built in of iron into the TiO(2) lattice. This iron is reactive in the photo-Fenton process resulting in high production of OH radicals and also high activity of the photocatalyst. At higher temperatures of heat treatment, less active FeTiO(3) phase is formed, therefore Fe-C-TiO(2) sample prepared at 800 degrees C showed low photocatalytic activity for dyes decomposition. Fe-C-TiO(2) photocatalysts are active under visible light irradiation, however, the efficiency of a dye decomposition is lower than under UV light. In a dark Fenton process there is observed an insignificant generation of OH radicals and very little decomposition of a dye, what suggests the powerful of photo-Fenton process in the dyes decomposition. 相似文献
15.
Nano sized ZnO powders, with suitable amount of TiO2 (P25), have been successfully synthesized via a novel modified hydrothermal method by using zinc acetate. Titania nano powder plays an important role in fabrication of ZnO nano structure. The structure and morphology of the product were characterized by X-ray diffraction and scanning electron microscopy, which show different morphologies and particle sizes. Photocatalytical properties of the product exhibit strong improvement in the reactivity of seeded powders. These powders have better properties because of coupling effect of semiconductors, small powder size and reduced recombination of electron-hole in the surface of a catalyst. 相似文献
16.
The hollow spheres of anatase TiO2 with higher photocatalytic activity have been fabricated by spherical CaCO3 nanoparticles as a template, and titanium sulfate (Ti(SO4)2) as a precursor, and the CaCO3 templates were dissolved subsequently in dilute HNO3 solution. The TiO2 hollow spheres samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and N2 adsorption-desorption isotherms. The characterization results indicate that as prepared TiO2 hollow spheres sample was transformed to anatase phase in calcined at 400 °C, and the anatase TiO2 hollow spheres have a higher specific surface area and show much better photocatalytic activity than commercial P25 in the photodegradation of Rhodamine B under the UV irradiation. 相似文献
17.
Photocatalytic properties of porous TiO2/Ag thin films 总被引:1,自引:0,他引:1
In this study, nanocrystalline TiO2/Ag composite thin films were prepared by a sol-gel spin-coating technique. By introducing polystyrene (PS) spheres into the precursor solution, porous TiO2/Ag thin films were prepared after calcination at a temperature of 500 °C for 4 h. Three different sizes (50, 200, and 400 nm) of PS spheres were used to prepare porous TiO2 films. The as-prepared TiO2 and TiO2/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 TiO2 films exhibited different porous structures. XRD results showed that all TiO2/Ag films exhibited a major anatase phase. The photodegradation of porous TiO2 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. 相似文献
18.
Yongai Zhai 《Materials Letters》2008,62(30):4563-4565
Nanostructure rutile TiO2 was prepared in a carboxyl-containing ionic liquid, 1-methylimidazolium-3-acetate chlorine ([AcMIm]Cl), by using TiOCl2 solution as a precursor at low temperature. The obtained nanostructure TiO2 was analyzed with fourier transform infrared (FTIR), X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). The as-prepared TiO2 present only rutile crystal phase and a novel flower-like morphology. The as-prepared rutile TiO2 shows better photocatalytic performance in the degradation of methyl orange. The template-directing performance of ionic liquid is due to the bidentate chelating complexation between the carboxylic functional group of ionic liquid and titania. 相似文献
19.
Arrays of TiO2 nanotubes were fabricated by the anodization of Ti foils and then used in assembling dye-sensitized solar cells (DSSCs). The role of the morphologies of the TiO2 nanotubes in the photovoltaic performances of the DSSCs was studied in terms of the surface topography and the tube length. The necessity of removing the nanoporous films from the surface of the nanotube arrays for good DSSC performance has been demonstrated. Also, it has been shown that appropriately increasing the tube length was an effective measure for enhancing both the short-circuit current density and the conversion efficiency of the DSSCs. 相似文献
20.
This study examined the characterization of nanoporous structured titanium dioxide and its application to dye-sensitized solar cells (DSSCs). TEM revealed nanopore sizes of 10.0 nm with a regular hexagonal form. When nanoporous structured TiO2 was applied to DSSC, the energy conversion efficiency was enhanced considerably compared with that using nanometer sized TiO2 prepared using a hydrothermal method. The energy conversion efficiency of the DSSC prepared from nanoporous structured TiO2 was approximately 8.71% with the N719 dye under 100 mW cm−2 simulated light. FT-IR spectroscopy showed that the dye molecules were attached perfectly to the surface and more dye molecules were absorbed on the nanoporous structured TiO2 than on the nano-sized TiO2 particles prepared using a conventional hydrothermal method. Electrostatic force microscopy (EFM) showed that the electrons were transferred rapidly to the surface of the nanoporous structured TiO2 film. 相似文献