Solar-driven production of hydrogen (H₂) from water splitting is considered as one of the promising ways to provide clean fuels. There are two critical issues for high efficient photocatalytic solar energy conversion. One is the extension of light absorption into visible light region, and the other is the enhancement of quantum efficiency at each wavelength. In the former case, the light absorption band strongly depends on the intrinsic band gap of the photocatalyst materials. Regarding to the latter case, enhancement of quantum efficiency has been attempted by improving the methods of modification and synthesis. In this presetation, defects, like oxygen vacancies, have been demonstrated to enhance photocatalytic activity for TiO₂, SrTiO₃ and other oxides due to excellent charge separation efficiency within their whole absorption band.[1-3] besides the surface defect, bulk defect like Ti³⁺ doped TiO₂ can be treated as another kind of bulk defect also were invstigated.[4] Normally, these oxides only absorb UV light due to their large band gap. We also investigated the effect of defects on the photocatalytic activity of visible light photocatalyst, like sulfides, which have an extended visible light absorption from UV to visible light region (~ 550 nm).[5] The results indicate that the defects within a certain concentration can promote the charge separation and enhance the photocatalytic performance.

[1] Huaqiao Tan, Zhao Zhao, Mang Niu, Chengyu Mao, Dapeng Cao, Daojian Cheng, Pingyun Feng and Zaicheng Sun. Nanoscale, 2014, 2：10216-10223

[2] Huaqiao Tan, Zhao Zhao, Wan-bin Zhu, Eric N. Coker, Binsong Li, Min Zheng, Weixing Yu, Hongyou Fan, and Zaicheng Sun, ACS Appl. Mater. Interfaces: 2014, 6：19184-19190

[3] Zhao Zhao, Huaqiao Tan, Haifeng Zhao, Yang Lv, Li-Jing Zhou, Yujiang Song and Zaicheng Sun, Chemical Communications, 2014, 50： 2755-2757

[4] Zhao Zhao, Xiaoyan Zhang, Guoqiang Zhang, Zhenyu Liu, Dan Qu, Xiang Miao, Pingyun Feng, Zaicheng Sun. Nano Research: 2015, 8(12): 4061-4071

[5] Xiaoyan Zhang, Zhao Zhao, Wanwan Zhang, Guoqiang Zhang, Dan Qu, Xiang Miao, Shaorui Sun, Zaicheng Sun*. Solution Small: 2016 ,12: 10.1002/smll.201503067