Facilitating charge transfer through an atomic coherent interface of a novel direct Z-scheme BiVO@CuSnS heterojunction to boost photocatalytic performance.

Direct Z-scheme photocatalytic systems are very promising composite photocatalysts, and their photocatalytic performance is highly associated with the quality of the interface within them. Herein, a novel direct Z-scheme heterojunction with a coherent interface has been presented for the first time. Specifically, the heterojunction was constructed by dispersing pre-prepared BiVO crystals into the reaction system to synthesize CuSnS, followed by a hydrothermal reaction. It is shown that CuSnS was deposited on the surface of each pre-prepared BiVO crystal as a thin layer heterogeneous nucleation to acquire a core-shell heterojunction. The BiVO@CuSnS heterojunction was found to possess an atomic coherent interface, which is formed through the bonding between the (121) plane of BiVO and the (112) plane of CuSnS, originating from the matching in the crystalline lattice between the two planes. The coherent interface facilitated the charge transfer from CuSnS to BiVO owing to the difference in their Fermi levels, thereby forming a built-in electric field pointing from CuSnS to BiVO. Reduced fluorescence emission and a shortened carrier lifetime reveal an obvious reduction in the inter-band charge recombination for the optimal BVO@CTS-0.19 sample. Consequently, BVO@CTS-0.19 shows remarkably enhanced photocatalytic performance in MO degradation, Cr reduction and oxygen evolution. The Z-scheme charge transfer mechanism for BVO@CTS-0.19 was verified by a suite of techniques. This work provides a universal strategy for building a coherent interface to develop high-performance direct Z-scheme heterojunctions.