Unique multi-hierarchical Z-scheme heterojunction of branching SnIn4S8 nanosheets on ZnIn2S4 nanopetals for boosted photocatalytic performance

Multinary metal sulfides are receiving more and more attention in the field of photocatalysis due to their excellent photoelectronic properties, but they usually suffer from the low photogenerated carrier separation efficiency and poor photostability. In this work, a dual multinary metal sulfides composite system is developed to address these issues. A unique multi-hierarchical Z-scheme heterojunction is successfully constructed by in-situ growth of branched SnIn4S8 nanosheets on nanopetals of flower-like ZnIn2S4. The prepared optimal composite photocatalyst displays significantly enhanced visible-light photocatalytic activity with H2 evolution rate of 2.988 mmol g−1h−1, Cr(VI) reduction rate constant of 0.094 min−1 and dye degradation rate constant of 0.152 min−1, which are 4.5, 9.4 and 19 times of bare SnIn4S8, and 2.9, 4.3 and 3.5 times of bare ZnIn2S4, respectively. The improved photocatalytic performance is primarily attributed to the abundant porous channels of the novel hierarchical flower-shaped architecture and the formation of the direct Z-scheme heterojunction, guaranteeing the richer active sites, better light harvesting, stronger redox capability, and more efficient charge transfer. This work demonstrates the promising applications of the SnIn4S8/ZnIn2S4 hybrid in energy and environmental photocatalysis fields, and should be instructive for the design and modification of multinary sulfide photocatalysts.