Hierarchical nanohybrid of CuS/NiS2/Ti3C2 heterostructure with boosting charge transfer for efficient photocatalytic hydrogen evolution

Fabricating heterostructure photocatalysts with co-catalysts can improve the separation and transfer of photo-induced electrons and holes for photocatalysis reactions. Herein, Ti3C2Tx nanosheets are obtained by chemical etching via the hydrothermal route and serve as a template for growing photocatalysts. NiS2 nanoparticles and CuS nanoneedles are deposited sequentially on the surface of Ti3C2Tx nanosheets to form “Type II” CuS/NiS2/Ti3C2Tx hierarchical heterostructure via the solvothermal method. The enormous nanoneedles morphology provides enlarged active sites for the photocatalytic processes. The fabricated CuS/NiS2/Ti3C2Tx heterostructure delivers an increased hydrogen generation rate of 32.66 mmol g−1 h−1, which is higher than that of pure CuS (2.38 folds), NiS2 (1.93 folds), and NiS2/Ti3C2Tx (1.71 folds). CuS/NiS2/Ti3C2Tx heterostructure also performs a superior hydrogen evolution retention of 97.7% after 4 cycles (one cycle lasts 4 h), implying its decent structural stability and light corrosion resistance. The reasons are ascribed to the constructed “Type II” heterostructure of CuS/NiS2 with higher active sites, improved conductivity, and efficient separation of electrons and holes. DFT calculation and Mott-Schottky plots results elucidate the formation mechanism of CuS/NiS2/Ti3C2Tx “Type II” structure. CuS/NiS2/Ti3C2Tx heterostructure also obtains a reduced bandgap with increased light absorption. The van der Waals force between 2D materials enhances the transfer of photo-generated electrons. This work demonstrates that designing hierarchical co-catalyst heterostructure without non-noble can effectively promote water splitting in the solar-to-chemical system.