Hydrogenated TiO2 (H-TiO2) is an efficient photocatalyst for H2 evolution and useful for the development of a green-energy economy. The role of oxygen vacancies (Vos) in the structure of H-TiO2 and in the photocatalytic H2 evolution is the topic of intense debate.
Jun Bao, Song Sun, and colleagues, University of Science and Technology of China, Hefei, using synchrotron facilities, have found that Vos extend from the surface to the bulk phase of TiO2 during the hydrogenation process and, therefore, contribute to the disorder of H-TiO2.
Vos introduce defect states that overlap with the conduction band (CB) and lead to a band tail, which results in the visible-light absorption of H-TiO2. By controlling the hydrogenation degree to restrict the CB tail to just above the H+/H2 redox potential, the most favorable disordered structure for visible-light-driven photocatalytic H2 evolution can be developed.
- Nature of Conduction Band Tailing in Hydrogenated Titanium Dioxide for Photocatalytic Hydrogen Evolution ,
Jiawei Xue, Xiaodi Zhu, Yi Zhang, Wendong Wang, Wei Xie, Jilong Zhou, Jun Bao, Ying Luo, Xiang Gao, Yong Wang, Ling-yun Jang, Song Sun, Chen Gao,