Novel S-scheme 2D/2D Bi₄O₅Br₂ nanoplatelets/g-C₃N₅ heterojunctions with enhanced photocatalytic activity towards organic pollutants removal

Removal of organic pollutants and pharma products in waste water using semiconductor photocatalysts has gained huge interest among recent days. However, low visible light absorption, recombination rate of charge carriers and less availability of reaction sites are still major obstacles for the photocatalysis process. Herein, an in situ-forming Bi₄O₅Br₂ nanosheets decorated on the surface g-C₃N₅ were prepared via simple hydrothermal method under ambient temperature. The basic pH condition plays a vital role in growing for Bi₄O₅Br₂ nanosheets. Various characterization studies such as TEM, SEM, PL and UV-DRS studies confirmed the formation of close contact between the Bi₄O₅Br₂ and g-C₃N₅ nanosheets. The construction of Bi₄O₅Br₂ nanoplatelets/g-C₃N₅ nanocomposite increases the surface-active sites and improving the separation efficiencies of excitons, which is greatly influenced in the degradation of ciprofloxacin and bisphenol-A pollutants. Meanwhile, the flow of electrons from the layered structured graphite carbon of g-C₃N₅ which enables excellent electrical contact in the heterojunction. Besides, the main free radicals were determined as e⁻ and ^•O₂⁻, and production level of free radicals were confirmed by radical trapping experiments. The possible degradation mechanism was proposed and discussed. Finally, this work provides a unique approach to in-situ preparation of heterojunction photocatalysts and demonstrates the prepared Bi₄O₅Br₂ nanoplatelets/g-C₃N₅ photocatalysts have great potential in the waste water management.