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Abstract: A novel visible-light-driven photocatalyst of Sr2Bi2O5 is prepared by solid-state reaction at 780 °C. The optical band gap of Sr2Bi2O5 is determined to be 2.87 eV by UV–Vis diffuse reflectance spectroscopy. Under both UV and visible-light irradiation, the photocatalytic activity for degrading methyl orange (MO) over Sr2Bi2O5 is higher than those over BiVO4, and SrBi2O4. The relationships between the photocatalytic properties of Sr2Bi2O5, SrBi2O4, and BiVO4 and their crystal structures are discussed. Among Sr2Bi2O5, SrBi2O4, and BiVO4, the higher photocatalytic activity of Sr2Bi2O5 is ascribed to its higher level of distortion of the metal–oxygen polyhedra, and the lower packing factor degree. [Copyright &y& Elsevier]

Abstract: Single anatase TiO2 nanocrystals with controllable crystallinity are prepared by a simple and readily available hydrothermal route. The crystallinity has been successfully manipulated via varying the temperature. TiO2-240 prepared at 240°C holds the highest crystallinity, i.e., the largest crystallite size of 14.2nm and the lowest lattice strain of 12.56×10−3, and the highest photocatalytic efficiency. The feasible method is also successfully applied in the synthesis of Eu3+-doped TiO2 (TiO2:Eu3+) nanoparticles. Both the photocatalytic activity of TiO2 and the photoluminescence (PL) properties of the TiO2:Eu3+ intensifies obviously as the crystallinity increases. The photocatalytic activity of nanoTiO2 and PL properties of the TiO2:Eu3+ are discussed in detail from the viewpoints of crystallinity based on various characterizations. This method can be developed for the deliberate synthesis of other functional nanomaterials. [Copyright &y& Elsevier]

Abstract: Sillenite-type Bi25GaO39 as an efficient photocatalyst was studied in the present paper. The compound synthesized by a solid state reaction method has a band gap of 2.95eV. It possesses a fair visible-light-response ability. The UV-light-induced photocatalytic activities for degrading methylene blue follow the decreasing order of anatase TiO2 >Bi25GaO39 >Bi12GeO20 >Bi24Ga2O39, different from Bi12GeO20 >Bi25GaO39 >Bi24Ga2O39 >TiO2 under visible light irradiation. The dispersion of Pt over Bi25GaO39 leads to an obvious increase in photocatalytic performance. The opener structure of Bi25GaO39 is proposed to explain the higher UV-light-induced photocatalytic activity, compared with Bi24Ga2O39 and Bi12GeO20. [Copyright &y& Elsevier]

Abstract: M2Sb2O7 (M=Ca, Sr) photocatalysts were synthesized by a solid state reaction method. The results concerning methyl orange (MO) photodecomposition generally show that the catalytic efficiency of Sr2Sb2O7 is much higher than that of Ca2Sb2O7 under UV light irradiation. The more open structure in Sr2Sb2O7 is suggested to be responsible for its higher photocatalytic activity. In the investigation on pH-dependent photocatalysis over Sr2Sb2O7 catalyst, the pseudo-first reaction rate k was found to be increased by about six times as the pH value decreases from 6.88 to 3.91. We believe that the decolorization of MO in neutral or alkaline conditions is primarily through a photocatalytic process, while the MO photosensitization and photolysis mechanisms play more important roles in acidic conditions. [Copyright &y& Elsevier]