Janus Z-scheme heterostructure of ZnIn2S4/MoSe2/In2Se3 for efficient photocatalytic hydrogen evolution

Abstract

Artificial manipulation of charge separation and transfer are central issues dominating hydrogen evolution reaction triggered via photocatalysis. Herein, through elaborate designing on the architecture, band alignment, and interface bonding mode, a sulfur vacancy-rich ZnIn2S4-based (Vs-ZIS) multivariate heterostructure ZnIn2S4/MoSe2/In2Se3 (Vs-ZIS/MoSe2/In2Se3) with specific Janus Z-scheme charge transfer mechanism is constructed through a two-step hydrothermal process. Steering by the Janus Z-scheme charge transfer mechanism, photogenerated electrons in the conduction band of MoSe2 transfer synchronously to the valence band of Vs-ZIS and In2Se3, resulting in abundant highly-active photogenerated electrons reserved in the conduction band of Vs-ZIS and In2Se3, therefore significantly enhancing the photocatalytic activity of hydrogen evolution. Under visible light irradiation, the optimized Vs-ZIS/MoSe2/In2Se3 with the mass ratio of MoSe2 and In2Se3 to ZnIn2S4 at 3 % and 30 %, respectively, performs a high hydrogen evolution rate of 124.42 mmol·g−1·h−1, about 43.5-folds of the original ZIS photocatalyst. Besides, an apparent quantum efficiency (AQE) of 22.5 % at 420 nm and favorable durability are also achieved over Vs-ZIS/MoSe2/In2Se3 photocatalyst. This work represents an important development in efficient photocatalysts and donates a sound foundation for the design of regulating charge transfer pathways.