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 (k_CT) 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 (k_CH4) of CsPbBr₃-GO NHSs showed a positive relation with k_CT, while the negative correlation between k_CH4 and k_CT 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.