Direct Z-Scheme Heterojunction of Ligand-Free FAPbBr3/α-Fe2O3 for Boosting Photocatalysis of CO2 Reduction Coupled with Water Oxidation.

Up to now, the majority of the developed photocatalytic CO2 reduction systems need to use expensive sacrificial reductants as electron source. It is still a huge challenge to drive the photocatalytic CO2 reduction using water as an electron source. Herein, we report a facile strategy for the construction of direct Z-scheme heterojunction of LF-FAPbBr3/α-Fe2O3, which is manufactured by the in situ and two-step controlled growth of ligand-free formamidinium lead bromide (LF-FAPbBr3) nanocrystals on the surface of α-Fe2O3 nanorods. The matchable energy levels and direct contact between LF-FAPbBr3 and α-Fe2O3 significantly accelerate the interfacial charge transfer, with a charge separation efficiency (ηseparation) of 93%, much higher than that of 11% shown by the ligand-capped FAPbBr3/α-Fe2O3 heterojunction. The resulting efficient separation and raised redox ability of photogenerated carriers endow the LF-FAPbBr3/α-Fe2O3 heterojunction with an outstanding photocatalytic performance for CO2 reduction (to CO and CH4) coupled with water oxidation (to O2), achieving a highest electron consumption rate of 175.0 μmol g-1 h-1 among the reported metal halide perovskite-based photocatalysts, which are 5 and 11 times higher in comparison with those of sole LF-FAPbBr3 and ligand-capped FAPbBr3/α-Fe2O3, respectively.