g-C₃N₄/SnS₂ van der Waals Heterostructures Enabling High-Efficiency Photocatalytic Hydrogen Evolution

Van der Waals (vdW) heterojunction has played an essential role in effectively utilizing solar energy for sustainable hydrogen production. Herein, a 2D/2D g-C₃N₄/SnS₂ photocatalyst with vdW heterojunction is developed by self-assembly contacting SnS₂ hexagonal nanoplates and g-C₃N₄ nanosheets. A reasonable Type-II charge transfer mechanism based on the vdW heterostructure is proposed and verified by hydroxyl radical generation test. Photocatalysts with vdW heterostructure enable high-efficiency H₂ production under the visible light illumination, of which the optimized rate is about seven times higher than that of SnS₂. Experimental analysis and corresponding density functional theory simulation jointly identify that enhanced photocatalytic activity is ascribed to the optimized behavior of photogenerated carriers and promotional interaction between reactants with catalysts. Specifically, charge redistribution and staggered band structure of the heterojunction intrinsically facilitate the efficient interfacial charge migration and separation. Diminished free energy of surface hydrogen adsorption reveals the easier hydrogen adsorption-desorption for a composite system from the viewpoint of thermodynamics. This work may be attractive for the implementation of rationally synthesizing catalysts for efficient photocatalytic water splitting.