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

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.