Construction of CoSx–ZnIn2S4 hollow nanocages derived from metal–organic frameworks for efficient photocatalytic hydrogen production

Abstract

Smart heterogeneous structures and rational photocatalyst design play an important role in photocatalytic hydrogen production. In this study, ZnIn₂S₄ (ZIS) nanosheets were grown in situ on the surface of CoS_x hollow nanocages, derived from ZIF-67 metal–organic frameworks, to obtain hierarchical CoS_x/ZnIn₂S₄ (CZIS) hollow heterostructured nanocages. The CZIS composites exhibited significant enhanced photocatalytic H₂ evolution performance as compared with pure ZIS and CoS_x. The optimal content of CoS_x was about 30 wt% and the corresponding H₂ production rate was 1538.4 μmol g⁻¹ h⁻¹, which was approximately 6.1 times that of the pure ZnIn₂S₄. The improved photocatalytic performance of the CZIS hollow nanocages was attributed to their hollow morphology and well-matched band structure. The hollow structure was favorable to the absorption and utilization of light because of the multiple reflections of light in the cavity. The close surface contact of CoS_x and ZnIn₂S₄ not only enhanced the carrier separation and inhibited the recombination of photogenerated carriers but it also provided a fast electron transport channel, resulting in significantly improved photocatalytic performance. This study has confirmed that hollow CoS_x polyhedra may be a potential alternative to precious metal photocatalytic co-catalysts for the hydrogen generation.