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

Exploring photocatalysts to promote CO₂ photoreduction into solar fuels is of great significance. We develop TiO₂/perovskite (CsPbBr₃) 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 CsPbBr₃ quantum dots (QDs) to TiO₂, resulting in the construction of internal electric field (IEF) directing from CsPbBr₃ to TiO₂ upon hybridization. The IEF drives the photoexcited electrons in TiO₂ to CsPbBr₃ upon light irradiation as revealed by in-situ X-ray photoelectron spectroscopy analysis, suggesting the formation of an S-scheme heterojunction in the TiO₂/CsPbBr₃ nanohybrids which greatly promotes the separation of electron-hole pairs to foster efficient CO₂ photoreduction. The hybrid nanofibers unveil a higher CO₂-reduction rate (9.02 μmol g^-1 h^-1) comparing with pristine TiO₂ nanofibers (4.68 μmol g^-1 h^-1). Isotope (¹³CO₂) tracer results confirm that the reduction products originate from CO₂ source.