Building surface defects by doping with transition metal on ultrafine TiO2 to enhance the photocatalytic H-2 production activity

Inefficient charge separation and limited light absorption are two critical issues associated with high-efficiency photocatalytic H-2 production using TiO2. Surface defects within a certain concentration range in photocatalyst materials are beneficial for photocatalytic activity. In this study, surface defects (oxygen vacancies and metal cation replacement defects) were induced with a facile and effective approach by surface doping with low-cost transition metals (Co, Ni, Cu, and Mn) on ultrafine TiO2. The obtained surface-defective TiO2 exhibited a 3-4-fold improved activity compared to that of the original ultrafine TiO2. In addition, a H-2 production rate of 3.4 mu mol/h was obtained using visible light (lambda > 420 nm) irradiation. The apparent quantum yield (AQY) at 365 nm reached 36.9% over TiO2-Cu, significantly more than the commercial P25 TiO2. The enhancement of photo catalytic H-2 production activity can be attributed to improved rapid charge separation efficiency and expanded light absorption window. This hydrothermal treatment with transition metal was proven to be a very facile and effective method for obtaining surface defects. (C) 2018, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.