Charge Carrier Dynamics of CsPbBr 3 /g-C 3 N 4 Nanoheterostructures in Visible-Light-Driven CO 2 -to-CO Conversion.

The photon energy-dependent selectivity of photocatalytic CO-to-CO conversion by CsPbBr nanocrystals (NCs) and CsPbBr/g-CN nanoheterostructures (NHSs) was demonstrated for the first time. The surficial capping ligands of CsPbBr NCs would adsorb CO, resulting in the carboxyl intermediate to process the CO-to-CO conversion via carbene pathways. The type-II energy band structure at the heterojunction of CsPbBr/g-CN NHSs would separate the charge carriers, promoting the efficiency in photocatalytic CO-to-CO conversion. The electron consumption rate of CO-to-CO conversion for CsPbBr/g-CN NHSs was found to intensively depend on the rate constant of interfacial hole transfer from CsPbBr to g-CN. An in situ transient absorption spectroscopy investigation revealed that the half-life time of photoexcited electrons in optimized CsPbBr/g-CN NHS was extended two times more than that in the CsPbBr NCs, resulting in the higher probability of charge carriers to carry out the CO-to-CO conversion. The current work presents important and novel insights of semiconductor NHSs for solar energy-driven CO conversion.