Perovskite CsCuCl x Br 3‐x Microcrystals: Band Structure, Photochemical Stability, and Photocatalytic Properties

Abstract Although Pb‐based metal halide perovskites (MHPs) have excellent photoelectric characteristics, its toxicity remains a limiting factor for its widespread application. In the paper, a series of CsCuCl x Br 3‐ x ( x =1, 2, 3) MHPs microcrystals were developed and their hydrogen evolution performance in ethanol and HX (X=Cl, Br) were also studied. Among them, CsCuCl 3 microcrystals exhibit high hydrogen evolution performance in both HX and ethanol, attributed to its longest average lifetime and suitable band structure. Additionally, the effect of different sacrificial agents on photocatalytic hydrogen production indicates that the photogenerated hole (h + ) plays a critical role. MHPs can maintain a dynamic equilibrium of dissolution and precipitation in HX saturated aqueous solutions, thereby overcoming the stability issues associated with perovskite. The phase transition of CsCuCl x Br 3‐ x during photocatalysis is monitored by XRD technique. CsCuCl 3 shows high stability in saturated HCl aqueous solution, and excellent photocatalytic performance with a hydrogen production rate of CsCuCl 3 microcrystals reached 103.98 μmol g −1 at 210 min. Our study expands the development prospects of CsCuCl 3 in the field of photocatalytic solar fuel generation.