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Visible-Light-Driven Cu(II)−(Sr1−yNay)(Ti1−xMox)O3 Photocatalysts Based on Conduction Band Control and Surface Ion Modification

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journal contribution
posted on 03.11.2010 by Xiaoqing Qiu, Masahiro Miyauchi, Huogen Yu, Hiroshi Irie, Kazuhito Hashimoto
Band-gap narrowing is generally considered to be a primary method in the design of visible-light-active photocatalysts because it can decrease the photo threshold to lower energies. However, controlling the valence band by up-shifting the top of the band or inducing localized levels above the band results in quantum efficiencies under visible light much lower than those under UV irradiation (such as those reported for N-doped TiO2: Science 2001, 293, 269. J. Phys. Chem. B 2003, 107, 5483). Herein, we report a systematic study on a novel, visible-light-driven photocatalyst based on conduction band control and surface ion modification. Cu(II)−(Sr1−yNay)(Ti1−xMox)O3 photocatalysts were prepared by a soft chemical method in combination with an impregnation technique. It is found that Mo6+ as well as Na+ doping in the SrTiO3 can lower the bottom of the conduction band and effectively extend the absorption edge to the visible light region. The Cu(II) clusters grafted on the surface act as a co-catalyst to efficiently reduce the oxygen molecules, thus consuming the excited electrons. Consequently, photocatalytic decomposition of gaseous 2-propanol into CO2 is achieved, that is, CH3CHOHCH3 + 9/2O2 → 3CO2 + H2O. For Cu(II)−(Sr1−yNay)(Ti1−xMox)O3 at x = 2.0% under visible light irradiation, the maximum CO2 generation rate can reach 0.148 μmol/h; the quantum efficiency under visible light is calculated to be 14.5%, while it is 10% under UV light irradiation. Our results suggest that high visible light photocatalytic efficiency can be achieved by combining conduction band control and surface ion modification, which provides a new approach for rational design and development of high-performance photocatalysts.