Synthesis of CsPbBr3/CsPb2Br5@silica yolk-shell composite microspheres: precisely controllable structure and improved catalytic activity for dye degradation

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.