Enhanced pollutant photodegradation activity of graphitic carbon nitride on via bismuth oxyhalide graphene hybridization and the mechanism study†

Abstract

Addressing the degradation of persistent organic pollutants like bisphenol A (BPA) and rhodamine B (RhB) with a photocatalyst that is both cost-effective and environmentally friendly is a notable challenge. This research presents the synthesis of an optimized g-C₃N₄/Bi₄O₅Br₂ composite featuring a Z-scheme heterojunction structure. The precise band alignment of this composite significantly enhances the separation of photogenerated charges and the production of dominant reactive species. The composite demonstrated exceptional photocatalytic performance, with BPA degradation efficiency nearing 98% and RhB achieving complete degradation within 80 and 35 min under visible light, respectively. These results are approximately 1.3 times greater than the individual performance of CN and BOB, surpassing recent literature benchmarks. Through EPR and free radical capture experiments, the role of h⁺ and ·O₂⁻ as the primary active free radicals in the degradation process have been confirmed. First-principles calculations validated the experimental results, indicating that the Z-type heterojunction is instrumental in generating active species, thus improving degradation efficiency. This study offers a promising strategy for the design of photocatalysts targeting emerging organic pollutants.

Keywords: Photocatalysis; g-C₃N₄; Bi₄O₅Br₂; Heterostructure; Water purification; Z-scheme.