Modification of Bi4O5Br2 nanoflowers with biowaste-derived HTCC for enhanced photocatalytic oxidative coupling of benzylamines

The photocatalytic oxidative coupling of amines is an economically efficient and environmentally friendly method for imine synthesis. However, the application of traditional photocatalytic materials is limited by their low visible-light utilization efficiency, poor stability, and harsh reaction conditions. Herein, Bi 4 O 5 Br 2 nanoflowers were prepared using N , N -dimethylformamide as the solvent without the use of surfactants. Waste biomass derived from cyanobacterial blooms was then subjected to hydrothermal treatment to obtain hydrothermal carbonization carbon (Cya-HTCC) and used for the modification of Bi 4 O 5 Br 2 . The resulting composite photocatalyst exhibits excellent photocatalytic oxidative coupling performance for amines. Results of characterization shows that there is a significant interaction between Cya-HTCC and Bi 4 O 5 Br 2 , forming a heterostructure, which improves the separation efficiency of photogenerated carriers. Experimental results indicate that under the optimal ratio, Bi 4 O 5 Br 2 /HTCC(5) achieves a conversion rate of 97.52 % for benzylamine within 4 h under visible-light irradiation using oxygen in the air as the oxidant, with the selectivity of the main product N-benzylidenebenzylamine reaching 97.94 %. The conversion rate is 2.1 times and 1.5 times those of bare Bi 4 O 5 Br 2 and Cya-HTCC, respectively. This work provides a new idea for the economical, sustainable, and green conversion of benzylamine.