Elegant Construction of ZnIn2S4/BiVO4 Hierarchical Heterostructures as Direct Z-Scheme Photocatalysts for Efficient CO2 Photoreduction

The ZnIn2S4/BiVO4 heterostructures were elegantly designed through assembling ZnIn2S4 nanosheets onto the surface of BiVO4 decahedrons. This composite photocatalyst exhibits efficient photocatalytic conversion of CO2 into CO with a detectable amount of CH4 in the presence of water vapor. An electron spin-resonance spectroscopy (ESR) technique and density function theory (DFT) calculation affirm the direct Z-scheme structure in ZnIn2S4/BiVO4. The larger surface photovoltage (SPV) change and the longer liquid photoluminescence (PL) lifetime of the heterostructure, compared to the individual ZnIn2S4 and BiVO4 components, demonstrate that the Z-scheme structure can effectively promote the recombination of the photogenerated holes in the valence band (VB) of the ZnIn2S4 nanosheet with the electrons in the conduction band (CB) of the decahedral BiVO4 and lead to the abundant electrons surviving in the CB of ZnIn2S4 and holes in the VB of BiVO4, thus enhancing photocatalytic CO2 reduction performance. This study may make a potential contribution to the rational construction and deep understanding of the underlying mechanism of direct Z-schemes for advanced photocatalytic activity.