Stabilizing CsPbBr3 quantum dots via interfacial S-scheme charge transfer for efficient CO2 photoreduction

All-inorganic CsPbBr 3 perovskite quantum dots (QDs) are promising photocatalysts for CO 2 reduction, but their application is limited by aggregation and photoinduced instability. Herein, a 2D/0D BiOBr/CsPbBr 3 S-scheme heterojunction was constructed by anchoring CsPbBr 3 QDs on BiOBr nanosheets. The 2D BiOBr support promotes uniform QD dispersion and exposes more accessible active sites. More importantly, the intimate interface establishes an internal electric field that favors directional interfacial charge transfer in an S-scheme configuration. This pathway facilitates the depletion of photogenerated holes from CsPbBr 3 while retaining strongly reductive electrons for CO 2 conversion, thereby improving charge separation and contributing to enhanced photostability. The optimized composite delivers CO and CH 4 evolution rates of 170.4 and 33.0 μmol g −1  h −1 , respectively, corresponding to 3.8- and 3.2-fold increases over pristine CsPbBr 3 QDs, together with improved cycling stability. XPS, UPS, KPFM, photoelectrochemical measurements, in situ FTIR spectroscopy, and DFT calculations collectively support the S-scheme mechanism and reveal a lower Gibbs free-energy requirement for COOH* formation. These synergistic effects account for the enhanced photocatalytic activity and stability. Download: Download high-res image (150KB) Download: Download full-size image