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

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 CsPbBr 3 /CsPb 2 Br 5 heterogeneous crystals into mesoporous hollow SiO 2 spheres to form the CsPbBr 3 /CsPb 2 Br 5 @SiO 2 yolk-shell microspheres. The composition modulation by simply adjusting the ratio of Cs + and Pb 2+ could result in the perovskite structure evolution from CsPbBr 3 to CsPbBr 3 /CsPb 2 Br 5 and CsPb 2 Br 5 . The prepared CsPbBr 3 /CsPb 2 Br 5 @SiO 2 were dispersed in the aqueous rhodamine B solutions and exhibited higher photocatalytic activities than the commercial TiO 2 (P25). The improvement in the photocatalytic efficiency is mainly caused by the formation of heterogeneous CsPbBr 3 /CsPb 2 Br 5 to boost the spatial charge separation efficiency. Graphical abstract