Pt Deposites on TiO2 for Photocatalytic H2 Evolution: Pt Is Not Only the Cocatalyst, but Also the Defect Repair Agent

Pt, as a common cocatalyst, has been widely used in photocatalytic H2 evolution. However, the specific role of Pt in photocatalytic H2 evolution has not been thoroughly studied. In this paper, by employing three Pt sources with different charges (positive, negative and neutral), we systematically studied the charge effect of Pt sources on photocatalytic H2 evolution via TiO2 catalyst. According to the results of Raman, X-ray photoelectron spectroscopy (XPS), recycle experiments and photocurrent characterizations, it was found that TiO2 would produce electropositive defects during photocatalytic H2 evolution, inevitably leading to the decline of H2 production activity. Thanks to the electrostatic interaction, the electronegative Pt source not only promoted charge separation, but preferential deposited on electropositive defects, which acted as the defect repair agent, and thus resulted in the increased photocatalytic stability. This work may provide a new perspective for enhancing photocatalytic stability of hydrogen production.