Cu-N-TiO₂/g-C3N4 photocathode-driven sediment microbial fuel cells for azithromycin degradation and enhanced bioelectricity generation

Abstract

The widespread occurrence of antibiotic pollutants such as azithromycin (AZI) in aquatic habitats needs the development of efficient and long-term cleanup solutions. This study looks into the use of photocatalysis in conjunction with sediment microbial fuel cells (SMFCs) to degrade AZI and generate bioelectricity. We developed and analyzed a novel heterojunction photocatalyst, Cu-N-TiO₂/g-C₃N₄, coated onto a graphene conductive material (GCM), which serves as an effective photocathode. Comprehensive characterization (XRD, XPS, UV-Vis, and SEM) confirmed successful heterojunction production, with XPS revealing important impurity states from N and Cu co-doping. The improved heterostructure had a dramatically narrower bandgap of 1.02 eV, which increased its visible-light absorption capability. The Cu-N-TiO₂/g-C₃N₄ photocathode outperformed pure g-C₃N₄ (70.95%), Cu-N-TiO₂ (65.64%), and the control (49.21%) in SMFCs using natural sunshine, attaining 84.73% AZI degradation. While AZI stress reduced microbial diversity and hence hindered energy generation, the improved photocathodes enabled sustained bioelectricity production. This study identifies sunlight-driven SMFCs with customized heterojunction photocathodes as a potential, synergistic technique for the effective cleanup of antibiotic-contaminated water.