Synergy between van der waals heterojunction and vacancy in ZnIn₂S₄/g-C₃N₄ 2D/2D photocatalysts for enhanced photocatalytic hydrogen evolution

Fabricating 2D/2D heterojunction with vacancy is more favorable to the spatial separation and transfer of charge owing to the matching of unique 2D structure and vacancy engineering, but the regulation and observation of interlayer forces and electronic structure is a challenging task for synthesizing heterojunction photocatalyst and studying the photocatalytic hydrogen evolution mechanism. Herein, an original 2D/2D ZnIn₂S₄/g-C₃N₄ Van der Waals heterojunction with S vacancies (ZIS-S/CN VDW) photocatalyst are firstly engineered. The optimized 30ZIS-S/g-C₃N₄ has the highest H₂ evolution rate of 6095.1 μmol h⁻¹ g⁻¹, which is primarily attributed to the fact that 2D/2D VDW heterojunction possesses larger contact area and strong electronic interaction to stimulate charge kinetics, and the vacancy engineering can enhance light absorption by regulating the electronic band structure and act as effective active sites for capturing electrons. This work not only enriches 2D/2D heterojunction photocatalytic system based on g-C₃N₄, but also provides alternative proposal for engineering 2D/2D heterojunction photocatalyst with satisfactory performance.