Highly Selective and Efficient Solar-Light-Driven CO2 Conversion with an Ambient-Stable 2D/2D Co2 P@BP/g-C3 N4 Heterojunction

Abstract

Renewable solar-driven carbon dioxide (CO₂ ) conversion to highly valuable fuels is an economical and prospective strategy for both the energy crisis and ecological environment disorder. However, the selectivity and activity of current photocatalysts have great room for improvement due to the diversification and complexity of products. Here, an ambient-stable 2D/2D Co₂ P@BP/g-C₃ N₄ heterojunction is designed for highly selective and efficient photocatalytic CO₂ reduction reaction. The resulting Co₂ P@BP/g-C₃ N₄ material has a remarkable conversion of CO₂ to carbon monoxide (CO) with an ≈96% selectivity, coupled with a dramatically increased CO generation rate of 16.21 µmol g^-1 h^-1 , which is 5.4 times higher than pristine graphitic carbon nitride (g-C₃ N₄ ). In addition, this photocatalyst exhibits good ambient stability of black phosphorus (BP) without oxidation even over 180 days. The excellent photocatalytic selectivity and activity of Co₂ P@BP/g-C₃ N₄ heterojunction are attributed to its lower energy barriers of *COOH, *CO, and *+CO in the process of CO₂ reduction, coupled with rapid charge transfer at the heterointerfaces of BP/g-C₃ N₄ and Co₂ P/BP. This is solidly verified by both density functional theory calculation and mechanism experiments. Therefore, this work holds great promise for an ambient-stable efficient and high selectivity photocatalyst in solar-driven CO₂ conversion.

Keywords: 2D/2D heterojunctions; ambient stable heterojunctions; black phosphorus; photocatalytic CO 2 reduction.