Ultrathin and Small‐Size Graphene Oxide as an Electron Mediator for Perovskite‐Based Z‐Scheme System to Significantly Enhance Photocatalytic CO2 Reduction

Abstract The judicious design of efficient electron mediators to accelerate the interfacial charge transfer in a Z‐scheme system is one of the viable strategies to improve the performance of photocatalysts for artificial photosynthesis. Herein, ultrathin and small‐size graphene oxide (USGO) nanosheets are constructed and employed as the electron mediator to elaborately exploit an efficient CsPbBr 3 ‐based all‐solid‐state Z‐scheme system in combination with α‐Fe 2 O 3 for visible‐light‐driven CO 2 reduction with water as the electron source. CsPbBr 3 and α‐Fe 2 O 3 can be closely anchored on USGO nanosheets, owing to the existence of interfacial strong chemical bonding behaviors, which can significantly accelerate the photogenerated carrier transfer between CsPbBr 3 and α‐Fe 2 O 3 . The resultant improved charge separation efficiency endows the Z‐scheme system exhibiting a record‐high electron consumption rate of 147.6 µmol g −1 h −1 for photocatalytic CO 2 ‐to‐CO conversion concomitant with stoichiometric O 2 from water oxidation, which is over 19 and 12 times higher than that of pristine CsPbBr 3 nanocrystals and the mixture of CsPbBr 3 and α‐Fe 2 O 3 , respectively. This work provides a novel and effective strategy for improving the catalytic activity of halide‐perovskite‐based photocatalysts, promoting their practical applications in the field of artificial photosynthesis.