A hierarchical SnS@ZnIn2S4 marigold flower-like 2D nano-heterostructure as an efficient photocatalyst for sunlight-driven hydrogen generation

Herein, we report thein situsingle-step hydrothermal synthesis of hierarchical 2D SnS@ZnIn(2)S(4)nano-heterostructures and the examination of their photocatalytic activity towards hydrogen generation from H2S and water under sunlight. The photoactive sulfides rationally integrateviastrong electrostatic interactions between ZnIn(2)S(4)and SnS with two-dimensional ultrathin subunits,i.e.nanopetals. The morphological study of nano-heterostructures revealed that the hierarchical marigold flower-like structure is self-assembledviathe nanopetals of ZnIn2S4 with few layers of SnS nanopetals. Surprisingly, it also showed that the SnS nanopetals with a thickness of similar to 25 nm couplein situwith the nanopetals of ZnIn(2)S(4)with a thickness of similar to 25 nm to form a marigold flower-like assembly with intimate contact. Considering the unique band gap (2.0-2.4 eV) of this SnS@ZnIn2S4, photocatalytic hydrogen generation from water and H2S was performed under sunlight. SnS@ZnIn(2)S(4)exhibits enhanced hydrogen evolution,i.e.650 mu mol h(-1)g(-1) from water and 6429 mu mol h(-1)g(-1)from H2S, which is much higher compared to that of pure Zn In2S4 and SnS. More significantly, the enhancement in hydrogen generation is 1.6-2 times more for H2S splitting and 6 times more for water splitting. SnS@ZnIn2S4 forms type I band alignment, which accelerates charge separation during the surface reaction. Additionally, this has been provoked by the nanostructuring of the materials. Due to the nano-heterostructure with hierarchical morphology, the surface defects increased which ultimately suppresses the recombination of the electron-hole pair. The above-mentioned facts demonstrate a significant improvement in the interface electron transfer kinetics due to such a unique 2D nano-heterostructure semiconductor which is responsible for a higher photocatalytic activity.