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

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 CsPbBr3 -based all-solid-state Z-scheme system in combination with α-Fe2 O3 for visible-light-driven CO2 reduction with water as the electron source. CsPbBr3 and α-Fe2 O3 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 CsPbBr3 and α-Fe2 O3 . 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 CO2 -to-CO conversion concomitant with stoichiometric O2 from water oxidation, which is over 19 and 12 times higher than that of pristine CsPbBr3 nanocrystals and the mixture of CsPbBr3 and α-Fe2 O3 , 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.