Coupling Benzylamine Oxidation with CO₂ Photoconversion to Ethanol over a Black Phosphorus and Bismuth Tungstate S‐Scheme Heterojunction

Abstract

Photoconversion of CO₂ and H₂ O into ethanol is an ideal strategy to achieve carbon neutrality. However, the production of ethanol with high activity and selectivity is challenging owing to the less efficient reduction half-reaction involving multi-step proton-coupled electron transfer (PCET), a slow C-C coupling process, and sluggish water oxidation half-reaction. Herein, a two-dimensional/two-dimensional (2D/2D) S-scheme heterojunction consisting of black phosphorus and Bi₂ WO₆ (BP/BWO) was constructed for photocatalytic CO₂ reduction coupling with benzylamine (BA) oxidation. The as-prepared BP/BWO catalyst exhibits a superior photocatalytic performance toward CO₂ reduction, with a yield of 61.3 μmol g^-1 h^-1 for ethanol (selectivity of 91 %).In situ spectroscopic studies and theoretical calculations reveal that S-scheme heterojunction can effectively promote photogenerated carrier separation via the Bi-O-P bridge to accelerate the PCET process. Meanwhile, electron-rich BP acts as the active site and plays a vital role in the process of C-C coupling. In addition, the substitution of BA oxidation for H₂ O oxidation can further enhance the photocatalytic performance of CO₂ reduction to C₂ H₅ OH. This work opens a new horizon for exploring novel heterogeneous photocatalysts in CO₂ photoconversion to C₂ H₅ OH based on cooperative photoredox systems.