Morphological modulation synthesis of Bi4O5Br2 for efficient photocatalytic oxidation of amines to imines

A variety of Bi 4 O 5 Br 2 photocatalysts were synthesized by different methods. • The microsphere-like Bi 4 O 5 Br 2 showed the best light absorption and charge transfer. • A remarkable enhanced activity for the photocatalytic oxidation of benzylamine. • The microsphere-like Bi 4 O 5 Br 2 manifested its excellent stability and versatility. A variety of bismuth-rich Bi 4 O 5 Br 2 (BOB) photocatalysts were synthesized by different methods. The impacts of synthesis approaches on the morphology, structure, composition, textural and optical-electronic properties of the as-fabricated Bi 4 O 5 Br 2 samples were systematically surveyed using various characterization techniques. The photocatalytic performance of the resulting Bi 4 O 5 Br 2 samples toward the oxidative coupling of benzylamine under simulated solar light illumination and air atmosphere was evaluated. It was found that the microsphere-like Bi 4 O 5 Br 2 (BOB-MS) showed the best photocatalytic property, with nearly complete conversion of benzylamine (BA) and 99.1% selectivity to N-benzylidene benzylamine (N-BDBA) after 2.5 h of light exposure. Besides, BOB-MS maintained high activity and excellent N-BDBA selectivity (>99.0%) during five consecutive cycles, demonstrating its brilliant stability and recyclability. In addition, for some benzylamine derivatives and heterocyclic amines, BOB-MS can also photocatalyze their transformation to the corresponding imines, manifesting the universal applicability of the catalyst. The results not only confirm the important influence of morphological modulation on the photocatalytic performance but also provide novel insights for the design of efficient and stable bismuth oxyhalide photocatalysts. Download: Download high-res image (362KB) Download: Download full-size image