Construction of S-Scheme Cs2AgBiBr6/BiVO4 Heterojunctions with Fast Charge Transfer Kinetics Toward Promoted Photocatalytic Conversion of CO2

Lead-based halide perovskites (LHPs) have been widely explored by researchers in the field of photocatalysis. However, the poor stability and toxicity of LHPs limit their large-scale applications. Here, lead-free Cs₂AgBiBr₆/BiVO₄ (CABB/BVO)-X% (X = 30, 50, 100) S-scheme heterojunction composites are prepared by electrostatic assembly, and their catalytic activity for photoreduction of CO₂ is evaluated. After 3 h of simulated solar irradiation, the prepared CABB/BVO-50% composites show the highest CO yield and electron consumption rate of 143.59 and 352.22 µmol g⁻¹, which are 9.2 and 7.8 times higher than that of CABB alone, respectively. In addition, the prepared CABB/BVO-50% photocatalysts exhibit 81.5% high selectivity for CO. The generation of an internal electric field (IEF) between the two materials and the generation of S-scheme heterojunctions are powerfully confirmed by employing various characterization techniques and DFT calculations. The low carrier recombination rate, bandgap-matched heterointerfaces, and exceptional S-scheme charge transfer mechanism are primarily responsible for the outstanding performance. This work provides new insights into the design of efficient lead-free perovskites-based photocatalytic materials.