Abstract
Heterogeneous metal halide perovskites (MHPs) are of great interest in photovoltaic and photocatalytic applications because of their high photon-to-electron conversion efficiency. However, the improvement in the stability of heterogeneous MHP is still a great challenge and has rarely been reported for polar solvent-based photocatalytic applications. Herein, we report a precisely controllable synthesis of CsPbBr3/CsPb2Br5 heterogeneous crystals into mesoporous hollow SiO2 spheres to form the CsPbBr3/CsPb2Br5@SiO2 yolk-shell microspheres. The composition modulation by simply adjusting the ratio of Cs+ and Pb2+ could result in the perovskite structure evolution from CsPbBr3 to CsPbBr3/CsPb2Br5 and CsPb2Br5. The prepared CsPbBr3/CsPb2Br5@SiO2 were dispersed in the aqueous rhodamine B solutions and exhibited higher photocatalytic activities than the commercial TiO2 (P25). The improvement in the photocatalytic efficiency is mainly caused by the formation of heterogeneous CsPbBr3/CsPb2Br5 to boost the spatial charge separation efficiency.