Accompanying Bi Clusters as Charge Mediators Effectively Enhance Synergetic Redox of Bi ₂ Sn ₂ O ₇ /ZnIn ₂ S ₄ S‐Scheme Heterostructure Composites

Achieving synergistic oxidation and reduction represents a significant challenge in the field of photocatalysis. In this study, the hydrothermal/in situ construction of Bi atom clusters within Bi₂Sn₂O₇/ZnIn₂S₄ (BSO/ZIS) heterostructures is reported. These clusters exhibit self-accelerating charge-transfer mechanisms facilitated by internal electric fields and bonding bridges, resulting in highly efficient light absorption and charge-transfer capabilities. In situ X-ray photoelectron spectroscopy (XPS) and Kelvin probe force microscopy (KPFM), as well as theoretical calculations, indicate that the canonical induction and promotion of electrons and holes by the Bi clusters lowers the activation energy of CHO* generation, allowing simultaneous CO₂ reduction and toluene oxidation over the catalyst, and enhances proton-coupling and electron-transfer processes, resulting in a unique reaction mechanism. The CO₂ and toluene as reactant, the Bi-Bi₂Sn₂O₇/ZnIn₂S₄ (B-BSO/ZIS) heterostructure achieves a CO₂ reduction rate to CO of 726.3 µmol g^-1 h^-1 (99.9% selectivity) and a toluene oxidation rate to benzaldehyde of 2362.0 µmol g^-1 h^-1 (98.0% selectivity), which increases in activity of 14.6 and 5.7 times compared to pristine ZnIn₂S₄. This study underscores the significance of modulating the photocatalytic pathway through the strategic selection of metal clusters and reactants, contributing to the rational design of photocatalysts for enhanced CO₂ adsorption and stabilization of *H.