Mechanisms behind photocatalytic CO2 reduction by CsPbBr3 perovskite-graphene-based nanoheterostructures

We demonstrate the CsPbBr3 nanoparticles can in-situ growth on semiconducting graphene oxide (GO) and conductive few-layer graphene (FLG) surfaces, individually. The type-II and Schottky-junction-like energy band structures of CsPbBr3-GO and CsPbBr3-FLG nanoheterostructures (NHSs) resulted in the varied interfacial charge transfer (CT) behaviors. The CT rate constant (kCT) of CsPbBr3-GO and CsPbBr3-FLG NHSs could be modulated by controlling their constituent ratio of GO/FLG. Moreover, the CO2−to−CH4 conversion rate (kCH4) of CsPbBr3-GO NHSs showed a positive relation with kCT, while the negative correlation between kCH4 and kCT for CsPbBr3-FLG NHSs was observed. The mechanism can be suggested as that the different energy band structures in CsPbBr3-graphehe-based NHSs provide the varied reduction potential for the photoexcited charge carriers to effect the performance in photocatalytic CO2 reduction. This work presents the important insights into the design of perovskite-graphene based NHS with remarkable performance for solar-driven CO2 conversion.