Unique S-scheme heterojunctions in self-assembled TiO2/CsPbBr3 hybrids for CO2 photoreduction

Abstract Exploring photocatalysts to promote CO 2 photoreduction into solar fuels is of great significance. We develop TiO 2 /perovskite (CsPbBr 3 ) S-scheme heterojunctions synthesized by a facile electrostatic-driven self-assembling approach. Density functional theory calculation combined with experimental studies proves the electron transfer from CsPbBr 3 quantum dots (QDs) to TiO 2 , resulting in the construction of internal electric field (IEF) directing from CsPbBr 3 to TiO 2 upon hybridization. The IEF drives the photoexcited electrons in TiO 2 to CsPbBr 3 upon light irradiation as revealed by in-situ X-ray photoelectron spectroscopy analysis, suggesting the formation of an S-scheme heterojunction in the TiO 2 /CsPbBr 3 nanohybrids which greatly promotes the separation of electron-hole pairs to foster efficient CO 2 photoreduction. The hybrid nanofibers unveil a higher CO 2 -reduction rate (9.02 μmol g –1 h –1 ) comparing with pristine TiO 2 nanofibers (4.68 μmol g –1 h –1 ). Isotope ( 13 CO 2 ) tracer results confirm that the reduction products originate from CO 2 source.