Construction of a p–n Type S-Scheme Heterojunction by Incorporating CsPbBr₃ Nanocrystals into Mesoporous Cu₂O Microspheres for Efficient CO₂ Photoreduction

Construction of a p–n heterojunction is an efficient strategy to promote interfacial carrier transportation and photocatalytic reaction. Herein, we report the fabrication of a p–n heterojunction by incorporating CsPbBr3 nanocrystals into a mesoporous Cu2O microsphere. The band structures of n-type CsPbBr3 and p-type Cu2O were analyzed by UV–vis absorption spectra, Mott-Schottky plots, and valence-band X-ray photoelectron spectra (VB-XPS). The results showed that CsPbBr3 and Cu2O have staggered band alignments, and the Fermi level (EF) of Cu2O is much lower than that of CsPbBr3. Based on these analyses, an S-scheme charge-transfer mechanism was proposed, which was validated by XPS and electron spin resonance (ESR) measurements. The CsPbBr3/Cu2O heterostructure showed enhanced CO2 photoreduction activity compared to the single counterparts, which could be attributed to the unique porous structure, efficient charge separation, and preservation of highly energetic electrons. This p–n heterostructure is expected to be a potential visible-light-driven photocatalyst for artificial photosynthesis.