Unique NiCo<sub>2</sub>S<sub>4</sub>@ZnS/CdS Yolk–Shell Heterojunction for Efficient Visible-Light-Driven Photocatalytic Water Splitting
Wenjing Wang, Teng Hou, Jiakun Wu, Hanchu Chen, Hui Wang, Yanyan Li, Shaoxiang Li, Haifeng Lin, Lei Wang
Abstract
Construction of rational heterojunction nanostructures is an effective approach to enhance photocatalytic performance of semiconductor photocatalysts for solar-driven hydrogen production from water splitting. Herein, a unique non-noble-metal hollow heterostructure NiCo2S4@ZnS/CdS assembled by a ZnS/CdS light absorber with tunable compositions and a yolk–shell NiCo2S4 cocatalyst was constructed for the first time. Interestingly, the yolk–shell NiCo2S4 microspheres have a uniform size, and the composition of the ZnS/CdS coating layer can be tuned via adjusting the cation-exchange reaction time. Remarkably, such hollow NiCo2S4@ZnS/CdS yolk–shell heterostructures displayed enhanced H2 evolution reaction (HER) activity of 20.17 mmol·g–1·h–1 under visible-light (λ > 420 nm) irradiation, approximately 14.4- and 5.6-fold that of ZnS/CdS and 3 wt % Pt-loaded ZnS/CdS, respectively. Moreover, the NiCo2S4@ZnS/CdS hybrids owned favorable photocatalytic stability as confirmed by the cycling and long-term H2 evolution tests. The excellent photocatalytic capacity of NiCo2S4@ZnS/CdS can be ascribed to the heightened light absorption enabled by the yolk–shell architecture, efficient charge transfer and separation by the interfacial heterojunctions, as well as numerous active sites from the NiCo2S4 cocatalyst. The findings presented here could enlighten the rational structural regulation of semiconductor nanomaterials to promote solar conversion and utilization.