Hydrothermal synthesis of p-C3N4/f-BiOBr composites with highly efficient degradation of methylene blue and tetracycline.

Construction of heterojunctions with band-suitable different semiconductors has been demonstrated to be an efficient approach to enhance the separation of photoinduced electrons and holes. In this paper, highly efficient heterojuction photocatalysts consisted of porous-C3N4 (p-C3N4) and flowerlike-BiOBr (f-BiOBr) were successfully synthesized via a deposition-hydrothermal method. The SEM and HRTEM images indicated that BiOBr were successfully deposited on the surface of p-C3N4 and the layered p-C3N4/f-BiOBr heterojunctions were formed between p-C3N4 and f-BiOBr. The optimum photocatalytic activity of the p-C3N4/f-BiOBr nanocomposites with weight ratio of 3%p-C3N4 exhibited dramatically improved visible-light photocatalytic activities with 98.42% and 94.25% degradation rates for methylene blue (MB) and tetracycline, respectively. The enhanced activity was mainly attributed to the unique heteojunction architecture, which creates large interfacial surface between the constituent materials for facilitating charge transfer and effectively inhibits the fast recombination of photogenerated electrons and holes. The active species trapping experiment indicated that the O2- was the dominating reactive oxidizing species of p-C3N4/f-BiOBr for MB degradation under visible light irradiation. Moreover, the as-prepared photocatalysts displayed excellent stability in the recycling experiments with no obvious decrease of the degradation efficiencies for MB and tetracycline. Furthermore, the possible photocatalytic degradation mechanism of MB over p-C3N4/f-BiOBr was proposed to better understand the reaction process. The work provides a facile route for rational design of heterojunction photocatalysts with promising prospect for the treatment of antibiotic residues in various wastewaters.