Department of Metallurgy and Ceramics Science, Graduate School of Science and Engineering, Tokyo Institute of Technology, Tokyo, Japan.
Phys Chem Chem Phys. 2011 Sep 7;13(33):14937-45. doi: 10.1039/c1cp21514k. Epub 2011 Jul 14.
We have fabricated an efficient visible-light-sensitive Cu(2+)-grafted Ce-doped ZnO photocatalyst (Cu(2+)-Ce(x)Zn(1-x)O) by adopting a metal ion doping and co-catalyst modification. Impurity states were formed below the conduction band (CB) edge in Ce(x)Zn(1-x)O, and these impurity states induce the visible-light absorption. Ce(x)Zn(1-x)O without a Cu(2+)-co-catalyst showed negligible visible-light activity due to the low reduction power of electrons in impurity levels. Surprisingly, Cu(2+)-modification over Ce(x)Zn(1-x)O drastically increased its visible-light activity. Excited electrons in impurity states can transfer to the Cu(2+)-ions on the surface and form Cu(2+)/Cu(+) redox couples, which cause the efficient oxygen reduction through a multi-electron reduction process. One of the striking features of the present study is that the metal doped semiconductors which were inactive due to their impurity states become efficient visible-light photocatalysts upon co-catalyst modification. The successful strategy used here for designing a highly active visible-light photocatalyst would provide numerous opportunities to develop an efficient metal-ion based visible-light photocatalyst.
我们通过金属离子掺杂和共催化剂修饰，制备了一种高效的可见光敏感的 Cu(2+)-接枝 Ce 掺杂 ZnO 光催化剂（Cu(2+)-Ce(x)Zn(1-x)O）。Ce(x)Zn(1-x)O 的导带（CB）边缘以下形成了杂质态，这些杂质态诱导可见光吸收。由于杂质能级中电子的还原能力较低，没有 Cu(2+)-共催化剂的 Ce(x)Zn(1-x)O 几乎没有可见光活性。令人惊讶的是，Cu(2+)-修饰 Ce(x)Zn(1-x)O 大大提高了其可见光活性。杂质态中的激发电子可以转移到表面的 Cu(2+)离子上，并形成 Cu(2+)/Cu(+)氧化还原对，通过多电子还原过程导致高效的氧气还原。本研究的一个显著特点是，由于杂质态而不活跃的金属掺杂半导体在共催化剂修饰后成为高效的可见光光催化剂。这里使用的成功策略为设计高效的基于金属离子的可见光光催化剂提供了许多机会。
