Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan.
J Am Chem Soc. 2010 Nov 3;132(43):15259-67. doi: 10.1021/ja105846n.
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 TiO(2): 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)-(Sr(1-y)Na(y))(Ti(1-x)Mo(x))O(3) photocatalysts were prepared by a soft chemical method in combination with an impregnation technique. It is found that Mo(6+) as well as Na(+) doping in the SrTiO(3) 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 CO(2) is achieved, that is, CH(3)CHOHCH(3) + (9)/(2)O(2) → 3CO(2) + H(2)O. For Cu(II)-(Sr(1-y)Na(y))(Ti(1-x)Mo(x))O(3) at x = 2.0% under visible light irradiation, the maximum CO(2) 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.
带隙缩窄通常被认为是设计可见光活性光催化剂的主要方法，因为它可以降低光阈值以降低能量。然而，通过向上移动能带的顶部或在能带上方诱导局部能级来控制价带，导致可见光下的量子效率远低于紫外线照射下的量子效率（例如，N 掺杂 TiO2 的报道：Science 2001, 293, 269. J. Phys. Chem. B 2003, 107, 5483）。在这里，我们报告了一种基于导带控制和表面离子修饰的新型可见光驱动光催化剂的系统研究。Cu(II)-(Sr(1-y)Na(y))(Ti(1-x)Mo(x))O3 光催化剂通过软化学方法与浸渍技术相结合制备。结果发现，Mo6+以及 Na+掺杂 SrTiO3 可以降低导带底部并有效地将吸收边缘扩展到可见光区域。接枝在表面上的 Cu(II)簇作为助催化剂有效地还原氧气分子，从而消耗激发电子。因此，实现了气态 2-丙醇在可见光照射下的光催化分解为 CO2，即 CH3CHOHCH3 + (9)/(2)O2 → 3CO2 + H2O。在可见光照射下，x = 2.0%的 Cu(II)-(Sr(1-y)Na(y))(Ti(1-x)Mo(x))O3 的最大 CO2 生成速率可达 0.148 μmol/h；可见光下的量子效率计算为 14.5%，而在紫外线照射下为 10%。我们的结果表明，通过结合导带控制和表面离子修饰，可以实现高光催化效率，为合理设计和开发高性能光催化剂提供了新途径。
