Copper Modulated Lead-Free Cs₄ MnSb₂ Cl₁₂ Double Perovskite Microcrystals for Photocatalytic Reduction of CO₂

In order to deal with the global energy crisis and environmental problems, reducing carbon dioxide through artificial photosynthesis has become a hot topic. Lead halide perovskite is attracted people's attention because of its excellent photoelectric properties, but the toxicity and long-term instability prompt people to search for new photocatalysts. Herein, a series of <111> inorganic double perovskites Cs₄ Mn_1-x Cu_x Sb₂ Cl₁₂ microcrystals (x = 0, 0.1, 0.2, 0.3, 0.4, and 0.5) are synthesized and characterized. Among them, Cs₄ Mn_0.7 Cu_0.3 Sb₂ Cl₁₂ microcrystals have the best photocatalytic performance, and the yields of CO and CH₄ are 503.86 and 68.35 µmol g^-1 , respectively, after 3 h irradiation, which are the highest among pure phase perovskites reported so far. In addition, in situ Fourier transform infrared (FT-IR) spectroscopy and electron spin resonance (ESR) spectroscopy are used to explore the mechanism of the photocatalytic reaction. The results highlight the potential of this class of materials for photocatalytic reduction reactions.