Z-Scheme Heterojunction CdIn₂S₄/BiVO₄ with a Spherical Structure for Photocatalytic CO₂ Reduction

Z-scheme heterojunction photocatalysts are at the forefront of carbon dioxide reduction research. However, BiVO4 faces challenges due to its inappropriate conduction band position and rapid charge carrier recombination. In this article, spherical CdIn2S4/BiVO4 Z-scheme heterojunction composites attached to coiled nanosheets were synthesized via a hydrothermal method, which improved the CO2 reduction efficiency and addressed these limitations. The morphology, crystal structure, band structure, and photoelectrochemical properties of the sample were further studied. The CdIn2S4/BiVO4 composites exhibit superior photocatalytic activity compared to pure CdIn2S4 and BiVO4, with the CdIn2S4/BiVO4 composite containing 25% BiVO4 yielding the highest CO and CH4 production rates of 4.51 μmol g–1 h–1 and 1.01 μmol g–1 h–1, respectively, after 6 h and achieving an 81.7% CO selectivity. The Z-scheme design effectively mitigates charge recombination, boosts electron transfer, and enhances the photocatalytic CO2 activity. The mechanism of photogenerated carrier transfer in catalysts was elucidated through density functional theory. This work offers insights and theories into the design and preparation of BiVO4-based heterojunction photocatalysts.