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

Summary Lead halide perovskites are prospective candidates for CO 2 photoconversion. Herein, we report copper-doped lead-free Cs 2 AgSbCl 6 double perovskite microcrystals (MCs) for gas-solid phase photocatalytic CO 2 reduction. The 0.2Cu@Cs 2 AgSbCl 6 double perovskite MCs display unprecedented CO 2 photoreduction capability with CO and CH 4 yields of 412 and 128 μmol g −1 , respectively. The ultrafast transient absorption spectroscopy reveals the enhanced separation of photoexcited carriers in copper-doped Cs 2 AgSbCl 6 MCs. The active sites and reaction intermediates on the surface of the doped Cs 2 AgSbCl 6 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 Cs 2 AgSbCl 6 MCs facilitate sturdy CO 2 adsorption and activation and strikingly enhance the photocatalytic performance. This work offers an in-depth interpretation of the photocatalytic mechanism of Cs 2 AgSbCl 6 doped with copper, which may provide guidance for future design of high-performance photocatalysts for solar fuel production.