Nitrogen-defect-modified g-C3N4/BaFe12O19 S-scheme heterojunction photocatalyst with enhanced advanced oxidation technology synergistic photothermal degradation ability of antibiotic: Insights into performance, electron transfer pathways and toxicity

In this research, nitrogen-defect-modified g-C3N4/BaFe12O19 S-scheme heterojunction composites were prepared by in-situ thermal polymerization approach and employed as a productive photo-Fenton catalyst for degrading antibiotic. The micromorphology, crystal structure, chemical composition and optical characteristics of the photocatalysts were evaluated by various testing approaches. The formation of the internal electric field between g-C3N4 and BaFe12O19 and the construction of the S-scheme heterojunction were confirmed by density functional theory and Kelvin probe force microscopy. Meanwhile, the nitrogen defect and photothermal effect of the g-C3N4/BaFe12O19 composite further accelerate the electron migration rate. The optimized g-C3N4/BaFe12O19-30 photocatalyst achieved 100% enrofloxacin removal within 10 min compared to monomer g-C3N4. The bactericidal activity experiment showed that the photocatalytic degradation products were low or non-toxic. Based on the above characterization experiments and density functional theory, the possible degradation mechanism of enrofloxacin was proposed. This research offers new insights for the synthesis of photocatalyst for wastewater treatment.