A facile synthesis of a ZIF-derived ZnS/ZnIn2S4 heterojunction and enhanced photocatalytic hydrogen evolution

Abstract

A facile synthetic route, by using rhombic dodecahedral zeolitic imidazolate framework-8 (ZIF-8) as the structure template, is devoted to fabricating the ZnS/ZnIn₂S₄ hybrid heterojunction; the compact heterostructure was produced by combining the sulfurization of ZIF-8 and the in situ precipitation of ZnIn₂S₄ in one pot. The resulting ZnS nanoparticles of about 100 nm were uniformly dispersed in the folds of flower-like ZnIn₂S₄, whose structure is beneficial for charge transfer at the heterointerface. The additional quantities of ZIF-8 are varied to find an optimum ratio of the two components to obtain the best photocatalytic activity. In the photocatalytic hydrogen generation irradiated by simulated solar light, all the ZnS/ZnIn₂S₄ hybrid photocatalysts displayed improved hydrogen production rates compared to single ZnS or ZnIn₂S₄, and the best hydrogen production rate of 453.4 μmol h⁻¹ g⁻¹ is obtained by ZnS/ZIS-20, whose value is approximately 4 times higher than that of single ZnIn₂S₄. The electrochemical properties of the ZnS/ZnIn₂S₄ hybrid photocatalysts were measured to explore the charge transfer mode at the interface, and the band structure and enhanced photocatalytic hydrogen generation mechanism have been proposed. The excellent recycling properties of hydrogen production indicated the prospective applications of this kind of ZIF-derived metal sulfide in photocatalytic reactions.