Au Single-Atom Interlayer Bridge Promotes Cross-Layer Charge Transport and Intrinsic Catalytic Dual-Sites Activation...

Layered photocatalysts are attractive for artificial photosynthesis, but their performance is often limited by inefficient charge transport across interlayer gaps and sluggish surface reaction kinetics. Herein, we propose a single-atom interlayer bridge strategy by introducing Au single atoms into layered Bi₄O₅Br₂ (AuIB-BOB) to address the above limitations. The incorporated Au atoms substitute Bi sites and are stabilized by a mixed O/Br coordination environment with an average local structure of Au₁O₃Br₂, forming a covalent bridge between the Br^- and [Bi₄O₅]²⁺ layers to provide an excellent pathway for cross-layer charge transport. Thus, holes that would otherwise remain confined in the Br^- layer are extracted and delivered to the surface O-oxidation sites, while photogenerated electrons are retained and utilized at the surface Bi-reduction sites. This directional charge redistribution considerably suppresses charge recombination, prolonging the average carrier lifetime from 19.5 to 109.7 ps. Meanwhile, the bridge-mediated charge transport activates the intrinsic Bi reduction sites and O oxidation sites synchronously, promoting CO₂ adsorption/activation and H₂O oxidation-related processes. Without sacrificial agents or photosensitizers, AuIB-BOB achieves a CO₂-to-CO evolution rate of 58.21 µmol g^-1 h^-1 in pure water. This work provides an atomic-level paradigm for regulating cross-layer charge transfer and unlocking intrinsic redox sites in layered photocatalysts.