2D-C₃N₄ encapsulated perovskite nanocrystals for efficient photo-assisted thermocatalytic CO₂ reduction

Very recently, halide perovskites, especially all-inorganic CsPbBr₃, have received ever-increasing attention in photocatalysis owing to their superior optoelectronic properties and thermal stability. However, there is a lack of study on their application in thermocatalysis and photo-thermocatalysis. Herein, we rationally designed a core-shell heterojunction formed by encapsulating CsPbBr₃ nanoparticles with the 2D C₃N₄ (m-CN) layer via a solid-state reaction (denoted as m-CN@CsPbBr₃). A series of experiments suggest that abundant adsorption and active sites of CO₂ molecules as well as polar surfaces were obtained by utilizing m-CN-coated CsPbBr₃, resulting in significant improvement in CO₂ capture and charge separation. It is found that the m-CN@CsPbBr₃ effectively drives the thermocatalytic reduction of CO₂ in H₂O vapor. By coupling light into the system, the activity for CO₂-to-CO reduction is further improved with a yield up to 42.8 μmol g^-1 h^-1 at 150 °C, which is 8.4 and 2.3 times those of pure photocatalysis (5.1 μmol g^-1 h^-1) and thermocatalysis (18.7 μmol g^-1 h^-1), respectively. This work expands the application of general halide perovskites and provides guidance for using perovskite-based catalysts for photo-assisted thermocatalytic CO₂ reduction.