Synthesis and photocatalytic hydrogen activity of Mo1−xS2 nanosheets with controllable Mo vacancies

Abstract

In this work, a novel Mo1−xS2 (Mo1−xS2/TiO2) with controllable Mo vacancies was successfully synthesized by simple NaBH4 treatment, which exhibits significantly enhanced hydrogen evolution reaction (HER) activity with lower overpotential and smaller Tafel slope in alkaline electrolyte. Compared with pure TiO2 or MoS2/TiO2, the H2 release rate of Mo1−xS2/TiO2 heterostructure photocatalyst was significantly increased when Mo1−xS2 serves as a co-catalyst. At optimal molar ratio of 2.5:1 Mo1−xS2/TiO2, the H2 release rate achieves 1561 μmol g−1 h−1 in triethanolamine solution, which is approximately 5.3 and 2.7 times of pure TiO2 and MoS2/TiO2, respectively. Through electrochemical analysis and first-principle density functional theory calculations, the faster separation and transfer of photogenerated electron and holes as well as higher HER activity improve the efficiency of photocatalytic hydrogen production. This work opens a new doorway for utilization of defective 2D sheet materials towards solar to H2 conversion.