Showing papers by "Xinchen Wang published in 2005"
TL;DR: The results reveal that sintering temperature significantly affects the structural stability and photocatalytic activity of titania and may be explained by the existence of macrochannels that increase photoabsorption efficiency and allow efficient diffusion of gaseous molecules.
Abstract: Light-harvesting macroporous channels have been successfully incorporated into a mesoporous TiO2 framework to increase its photocatalytic activity. This bimodal porous material was characterized by X-ray diffractometry in both low-angle and wide-angle ranges, N2 adsorption−desorption analysis, scanning and transmission electron microscopy, FT-IR, and diffuse reflectance spectroscopy. Ethylene photodegradation in gas-phase medium was employed as a probe reaction to evaluate the photocatalytic reactivity of the catalysts. The results reveal that sintering temperature significantly affects the structural stability and photocatalytic activity of titania. The catalyst which calcined at 350 °C possessed an intact macro/mesoporous structure and showed photocatalytic reactivity about 60% higher than that of commercial P25 titania. When the sample was calcined at 500 °C, the macroporous structure was retained but the mesoporous structure was partly destroyed. Further heating at temperatures above 600 °C destroyed ...
444 citations
TL;DR: This novel ordered mesoporous Pt/TiO2 nanoarchitecture is also a promising photochemical material, as demonstrated by the photo-driven killing of Micrococcus lylae cells on the film.
Abstract: A novel metal/semiconductor nanocomposite with catalytic and photocatalytic functions has been prepared. The new material consists of highly dispersed platinum (Pt) nanoparticles embedded in a cubic mesoporous nanocrystalline anatase (meso-nc-TiO2) thin film. The porous thin film possesses a narrow pore-size distribution and a large surface area. The diameter of the Pt cluster can be controlled to below 5 nm, and the high dispersion of these clusters gives rise to catalytic activity for the oxidation of carbon monoxide, an important reaction for automobile exhaust treatment. This novel ordered mesoporous Pt/TiO2 nanoarchitecture is also a promising photochemical material, as demonstrated by the photo-driven killing of Micrococcus lylae cells on the film.
155 citations
TL;DR: In this article, Nanocrystalline TiO2 samples with mesoporous structure were obtained from media of different acidities including nitric acid, deionized water, and ammonia (denoted as HT-1, HT-2 and HT-3, respectively).
112 citations
71 citations
TL;DR: A Ag/TiO2 nanocomposite, in which silver nanoparticles are highly dispersed in the uniformly sized pores of a cubic mesoporous TiO2 molecular-sieve film, has been fabricated.
66 citations
TL;DR: Wurtzite ZnS was prepared by a novel low-temperature and mild solvothermal process over a temperature range of 160−200 °C as mentioned in this paper, where the solvent not only acts as a thermal conducting medium and extractant or active nucleophilic agent but also stabilizes the metastable wurtzites phase.
Abstract: Wurtzite ZnS, a high-temperature polymorph of ZnS, was prepared by a novel low-temperature and mild solvothermal process over a temperature range of 160−200 °C. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and high resolution transmission electron microscopy (HRTEM) analytic techniques were applied to characterize the composition and morphology of the products. The effects of solvent properties and reaction temperatures on the product purities and crystal structures were investigated. The solvent not only acts as a thermal conducting medium and extractant or active nucleophilic agent but also stabilizes the metastable wurtzite phase. As a result, the high-temperature wurtzite ZnS polymorph can be formed under low-temperature solvothermal conditions. TEM observations denote that the synthesized wurtzite ZnS consists of quasi-square or rectangle nanoplate-like morphologies with lateral dimensions ranging f...
65 citations
TL;DR: In this article, a new class of high-efficiency oxidation catalysts has been prepared using a combined surfactant and colloidal crystal templating method, which possess mesoporous structures and macrochannels.
Abstract: A new class of high-efficiency oxidation catalysts has been prepared using a combined surfactant and colloidal crystal templating method. The Pd/CexZr1−xO2 products possess mesoporous structures and macrochannels. XRD and EXD analyses confirmed the formation of a 0.8 wt.% Pd/Ce0.6Zr0.4O2 with a cubic phase at temperatures above 700 °C. With increasing calcination temperature, better crystallization of the cubic phase and incorporation of more zirconium into the ceria lattice were observed. The extent of surface Ce3+ and oxygen vacancies on the samples were studied by the XPS measurements. The T50 and T90 for CO oxidation over Pd supported catalysts were 65 °C and 75 °C respectively. These values were better than those obtained from catalysts without macrochannel structures and the one prepared by the co-precipitation method. Such high catalytic efficiency can be explained by the high crystal phase homogeneity, availability of more oxygen vacancies and an enlarged surface area.
38 citations
TL;DR: In this paper, a mechanism was proposed to elucidate the promoting effect of H2 on the photooxidation of volatile organic pollutants over Pt/TiO2, which showed that the introduced H2 has several beneficial effects on heterogeneous photocatalysis, namely, a comparatively clean surface of Pt/ TiO2 with no persistent aromatic intermediates, an increased number of surface hydroxyl radicals in the photocatalytic process, and an enhanced separation efficiency of photogenerated electron-hole pairs.
Abstract: Superior photocatalytic activity and durability of Pt/TiO2 for decomposing volatile organic pollutants (typically aromatic compounds) have been obtained by adding trace H2 into an O2-rich photooxidation system. The order of photodegradation efficiencies for volatile organic compounds is cyclohexane < acetone < benzene < toluene < ethylbenzene. Exceptional stability of Pt/TiO2 for benzene photodegradation is still maintained after 22 h of testing, by the repeated use of the catalyst four times. The promoting effects of H2 in the photocatalysis were studied by infrared spectroscopy (IR), spin-trapping electron paramagnetic resonance (EPR) and surface photovoltage spectroscopy (SPS). Results demonstrated that the introduced H2 has several beneficial effects on heterogeneous photocatalysis, namely, a comparatively clean surface of Pt/TiO2 with no persistent aromatic intermediates, an increased number of surface hydroxyl radicals in the photocatalytic process, and an enhanced separation efficiency of photogenerated electron–hole pairs. A mechanism is proposed to elucidate the promoting effect of H2 on the photooxidation of volatile organic pollutants over Pt/TiO2.
32 citations