CsPbBr₃-Modified Oxygen-Doped g-C₃N₄ Heterojunctions for Sulfurization of Alkenes to Sulfoxides

<i>Z</i>-scheme heterostructures have become a novel class of photocatalysts that hold substantial significance in the domains of environmental and energy-related applications. This can be attributed to their distinctive charge separation and transfer pathways, which endow <i>Z</i>-scheme heterojunctions with robust redox capabilities. In this paper, we report a straightforward method for fabricating a perovskite-based <i>Z</i>-scheme heterojunction by integrating CsPbBr₃ nanocrystals with oxygen-doped g-C₃N₄ (OCN). This heterojunction exhibited a high photocatalytic activity in the selective sulfoxidation reaction of alkenes with thiols. Under aerobic conditions, moderate to excellent yields of high-value sulfoxides with good functional compatibilities were achieved. This heterojunction showcases outstanding photocatalytic performance, remarkable stability, operational simplicity, high atom efficiency, and eco-friendly energy sources. The formation of <i>Z</i>-scheme heterojunction was corroborated by in situ X-ray photoelectron spectroscopy. These spectra revealed a negative shift in the binding energies of Cs 1s, Pb 4f, and Br 3d in CsPbBr₃, while a positive shift was observed for C 1s, N 1s, and O 1s in OCN upon light irradiation. This specific shift pattern effectively promotes the <i>Z</i>-scheme electron transfer from OCN to CsPbBr₃, which is conducive to the separation of electrons and holes, thereby enhancing the photoredox catalytic activity.