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 nano needles 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. & COPY; 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

Ti3C2Tx nanosheets are used as a template for growing CuS/NiS2/Ti3C2Tx hierarchical heterostructure, which provides enlarged active sites for photocatalytic processes. The heterostructure exhibits increased hydrogen generation rate and retention, attributed to improved conductivity and efficient separation of electrons and holes.