Unique S-scheme heterojunctions in self-assembled TiO ₂/CsPbBr ₃ hybrids for CO ₂ 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 ( ¹³CO ₂) tracer results confirm that the reduction products originate from CO ₂ source.

Abstract

Rational design and fabrication of high-performance photocatalyst is of great importance for CO ₂ reduction into solar fuel. Here, the authors demonstrate that S-scheme heterojunction TiO ₂/CsPbBr ₃ photocatalyst exhibits enhanced CO ₂ photoreduction activity.