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Nanosized porous In(OH)3 photocatalysts with high surface areas (as much as 110 m²∙g-1) were successfully synthesized by peptization of colloidal precipitates under ultrasound radiation. The resulting catalysts were characterized by X-ray powder diffraction (XRD), thermogravimetric analysis, nitrogen adsorption, transition electron microscopy, and UV—vis diffuse reflection spectroscopy. The photocatalytic activities of the samples were evaluated by the gas-phase decomposition of several volatile organic pollutants (acetone, benzene, and toluene) under UV light illumination and were compared with that of the commercial titania (Degussa P25). Results revealed that the as-synthesized In(OH)3 exhibited much higher photocatalytic activity and durability than both In2O3 and TiO2. One, therefore, can conclude that nanosized In(OH)3 has potential application in environmental treatment, especially in the removal of benzene-containing exhaust emissions from shoemaking plants in China. The excellent photocatalytic performance of In(OH)3 can be attributed to its strong oxidation capability, abundant surface hydroxyl groups, and high BET surface area as well as the porous texture. [ABSTRACT FROM AUTHOR]

Pure cubic In2O3, orthorhombic InOOH and cubic In(OH)3nanocrystals were separately synthesized viaa one-pot aqueous solvothermal route at low temperature by simply regulating the amount of water in the ternary system H2O–DMF–In(NO3)3·4.5H2O. [ABSTRACT FROM AUTHOR]

The majority of bismuth containing oxides have been taken as important functional materials for applications including photocatalytic water splitting and highly conductive solid electrolytes, which however suffer from property degradation owing to the presence of intermediates. This work initiated a case study on α-Bi2O3nanoparticles with an aim to uncover the origin of property degradation when bismuth oxides that contain traces of secondary phase α-Bi2O3were exposed in either air or aqueous solutions. First, α-Bi2O3nanoparticles with spherical and rod-like morphologies were prepared by developing solution chemistries. It was found that α-Bi2O3transformed partially to Bi2O2CO3when stored in air for 6 months. Such transformation was further accelerated when α-Bi2O3nanoparticles were exposed to water or methylene blue (MB) solution, probably because α-Bi2O3reacts with the species HCO3−as formed by dissolution of CO2from air. Bi2O3surfaces had an unusual tendency to adsorb MB molecules, which in turn prevented the reaction between α-Bi2O3and HCO3−. Consequently, MB solution became clear even without light irradiation. The results reported in this work may help to fully comprehend the property degradation of bismuth containing oxides when used in aqueous solutions. [ABSTRACT FROM AUTHOR]

Highly crystalline SnO2 nanocrystals with and without Zn2+ doping were directly prepared by a solvothermal method. By systematic characterizations using x-ray diffraction, transmission electron microscopy, infrared spectra, and UV-vis spectra, it is demonstrated that all samples crystallized in a single phase of rutile structure, and that upon Zn2+ doping particle sizes closer to the exciton Bohr radius (2.7 nm) of SnO2 were achieved, while the particle size of SnO2 nanoparticles was as large as about 12 nm without Zn2+ doping. The smaller particle sizes for Zn2+ doped nanoparticles had led to a lattice expansion, a blue-shift of the surface phonon mode for the anti-symmetric Sn-O stretching vibration, and a significantly narrowed band-gap energy, opposite to what is theoretically predicted by the quantum size effect. The photocatalytic activity of the doped samples is measured by monitoring the degradation of methylene blue dye in an aqueous solution under UV-radiation exposure. It is found that Zn2+ doped SnO2 showed excellent activity toward photodegradation of methylene blue solution under UV light irradiation. These observations were interpreted in terms of the Zn2+ doping at the surface sites of SnO2 nanoparticles and the relevant defects that have increased the surface active sites and moreover improved the ratio of surface charge carrier transfer rate to the electron-hole recombination rate. These results illustrate the potential of rationally modifying the particle size and surface defect characteristics for novel semiconductor oxide photocatalysts. [ABSTRACT FROM AUTHOR]