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

Abstract

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.