Fabricating a Z-Scheme Heterojunction of CTF@Cs₃Sb₂Br₉ Nanocomposites for Enhanced and Selective Photocatalytic Oxidation of Benzyl Alcohol

The selective oxidation of benzyl alcohols to the corresponding aldehydes is a highly desirable transformation, but significant challenges remain. Herein, we report a simultaneous-promotion strategy for redox capacities that involves the fabrication of an environmentally friendly, lead-free Cs₃Sb₂Br₉ nanocrystals (NCs)-based Z-scheme heterojunction. Cs₃Sb₂Br₉ NCs were grown on covalent triazine framework (CTF) nanosheets through ligand-assisted reprecipitation. The resulting CTF@Cs₃Sb₂Br₉ consisted of homogeneous Cs₃Sb₂Br₉ NCs (15 nm) attached to the surface of the CTF. Importantly, the nanocomposite significantly enhanced the spatial charge separation, thereby resulting in unprecedented photocatalytic efficiency and selectivity in the oxidation of benzyl alcohol. Especially, CTF@Cs₃Sb₂Br₉ exhibited 100% selectivity and up to 66.4% conversion of benzaldehyde in the photocatalytic oxidation of benzyl alcohol under ultraviolet light illumination. These results significantly exceed previously reported selectivity and conversions in benzyl alcohol oxidation reactions and therefore broaden the photocatalytic applications of environmentally friendly lead-free perovskite-based photocatalysts.