ZnSe Nanorods–CsSnCl₃ Perovskite Heterojunction Composite for Photocatalytic CO₂ Reduction

Utilizing sunlight to convert CO₂ into chemical fuels could simultaneously address the greenhouse effect and fossil fuel crisis. ZnSe nanocrystals are promising candidates for photocatalysis because of their low toxicity and excellent photoelectric properties. However, pristine ZnSe generally has low catalytic activities due to serious charge recombination and the lack of efficient catalytic sites for CO₂ reduction. Herein, a ZnSe nanorods-CsSnCl₃ perovskite (ZnSe-CsSnCl₃) type II heterojunction composite is designed and prepared for photocatalytic CO₂ reduction. The ZnSe-CsSnCl₃ type II heterojunction composite exhibits enhanced photocatalytic activity for CO₂ reduction with respect to pristine ZnSe nanorods. The experimental characterizations and theoretical calculations reveal that the efficient charge separation and lowered free energy of CO₂ reduction facilitate the CO₂ conversion on the ZnSe-CsSnCl₃ heterojunction composite. This work presents a type II heterojunction composite photocatalyst based on ecofriendly metal chalcogenides and metal halide perovskites. Our study has also promoted the understanding of the CO₂ reduction mechanisms on perovskite nanocrystals, which could be valuable for the development of metal halide perovskite photocatalysts.