Charge Carrier Dynamics of CsPbBr₃/g-C₃N₄Nanoheterostructures in Visible-Light-Driven CO₂-to-CO Conversion

The photon energy-dependent selectivity of photocatalytic CO₂-to-CO conversion by CsPbBr₃nanocrystals (NCs) and CsPbBr₃/g-C₃N₄nanoheterostructures (NHSs) was demonstrated for the first time. The surficial capping ligands of CsPbBr₃NCs would adsorb CO₂, resulting in the carboxyl intermediate to process the CO₂-to-CO conversion via carbene pathways. The type-II energy band structure at the heterojunction of CsPbBr₃/g-C₃N₄NHSs would separate the charge carriers, promoting the efficiency in photocatalytic CO₂-to-CO conversion. The electron consumption rate of CO₂-to-CO conversion for CsPbBr₃/g-C₃N₄NHSs was found to intensively depend on the rate constant of interfacial hole transfer from CsPbBr₃to g-C₃N₄. An in situ transient absorption spectroscopy investigation revealed that the half-life time of photoexcited electrons in optimized CsPbBr₃/g-C₃N₄NHS was extended two times more than that in the CsPbBr₃NCs, resulting in the higher probability of charge carriers to carry out the CO₂-to-CO conversion. The current work presents important and novel insights of semiconductor NHSs for solar energy-driven CO₂conversion.