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.