Article Enhanced photocatalytic activity and mechanism insight of copper-modulated lead-free Cs2AgSbCl6 double perovskite microcrystals

Lead halide perovskites are prospective candidates for CO2 photoconversion. Herein, we report copper-doped lead-free Cs2AgSbCl6 double perovskite microcrystals (MCs) for gas-solid phase photocatalytic CO2 reduction. The 0.2Cu@Cs2AgSbCl6 double perovskite MCs display unprecedented CO2 photo -reduction capability with CO and CH4 yields of 412 and 128 mmol g(-1) , respec-tively. The ultrafast transient absorption spectroscopy reveals the enhanced separation of photoexcited carriers in copper-doped Cs2AgSbCl6 MCs. The active sites and reaction intermediates on the surface of the doped Cs2AgSbCl6 are dynamically monitored and precisely unraveled based on the in-situ Fourier transform infrared spectroscopy investigation. In combination with density functional theory calculations, it is revealed that the copper-doped Cs2AgSbCl6 MCs facilitate sturdy CO2 adsorption and activation and strikingly enhance the photocatalytic performance. This work offers an in-depth interpretation of the photocatalytic mechanism of Cs2AgSbCl6 doped with copper, which may provide guidance for future design of high-performance photocata-lysts for solar fuel production.