Construction of Asymmetric Anion Layer to Accelerate Carrier Reaction Kinetics and Thermodynamically Promote Photocatalytic CO₂ Reduction

Abstract The efficient photocatalytic reduction of CO₂ into value‐added chemicals is significantly challenged by the charge carrier separation and transfer kinetics of photocatalysts as well as the thermodynamics of the CO₂ reduction process. Herein, it proposes a heterojunction with asymmetric W‐Cl anion layer in Bi₂WO₆ (abbreviated as BWOC). The asymmetric W‐Cl anion layer results in unbalanced electron density distribution and thus enables to establish atomic‐level donor–acceptor structure as well as larger electrostatic potential in the heterojunction, which facilitate the charge carrier separation and transfer kinetics. Simulation on the intermediates of the CO₂ photoreduction process demonstrates that Bi₂WO₆ with asymmetric W‐Cl anion layer possesses smaller energy barrier for the rate‐determining step of *COOH endothermic formation, and it is thermodynamically more favorable to generate CO as further confirmed by the detection of intermediates over in situ Fourier transform infrared spectroscopy. As a result, BWOC achieved rather high CO yield with the value of 32.11 µmol g⁻¹ h⁻¹ which is nearly four times higher than that of pure Bi₂WO₆. The construction of asymmetric anion layer in this work provides new insights for the design of efficient photocatalytic systems toward CO₂ reduction.