Targeted Electron‐Hole Separation to Decoupled Redox‐Active Sites Over a PEA2PbBr4/CeO2 P‐N Heterojunction for Enhanced Photocatalytic Oxidation

Abstract

Photocatalytic selective oxidation of C(sp3)─H bonds into valuable carbonyl compounds offers a promising approach to advance green organic synthesis and contribute to a more sustainable chemical industry. However, significant challenges remain due to the low efficiency of photocatalysts, primarily caused by insufficient charge separation and the limited ability of intermixed surface redox‐active sites to precisely capture photoinduced charge carriers. Here, a PEA2PbBr4/CeO2 (PPB/CeO2) p‐n heterojunction is designed and fabricated. Experimental characterizations and theoretical calculations reveal that a strong internal electric field (IEF) is formed at the interface within the p‐n heterojunction, which drives targeted accumulation of holes on PPB and electrons on CeO2. Importantly, CeO2 displays superior oxygen affinity facilitating O2 reduction, while PPB validates stronger adsorption and activation capability to toluene molecule promoting C─H bond dissociation. In this context, the photoinduced electrons and holes are directionally separated and transported to the decoupled reduction and oxidation sites in the PPB/CeO2, thereby significantly accelerating the aerobic oxidation of C(sp3)─H bonds. Toward photocatalytic oxidation of model substrate toluene, the optimized PPB/CeO2‐5% composite exhibits a toluene conversion rate of 10 050 µmol g−1 h−1, which is nine times enhanced in comparison with blank PPB (1160 µmol g−1 h−1).