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

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.