Facile preparation of Fe-C₃N₄ heterojunction for enhanced pollutant degradation in Fenton-like process

In this study, Fe-C₃N₄ composite was synthesized via high-temperature calcination and employed for enhanced pollutants degradation in Fenton-like process. The typical thiazine dye methylene blue (MB) acted as the target contaminant to research the activity of the proposed catalytic system. The physicochemical properties of the Fe-C₃N₄ catalyst were systematically characterized by various techniques, and different reaction parameters were examined to optimize the catalytic process. In the Fe-C₃N₄/H₂O₂ catalytic system, 100 mL 5 mg/L MB could be entirely degraded within 60 min by adding 0.15 g/L catalyst and 10 mM H₂O₂, and the high efficiency could be maintained around a wide pH range 3–11. The results of quenching experiments and electron paramagnetic resonance (EPR) analysis showed that hydroxyl radical (·OH) and singlet oxygen (¹O₂) were the main active species generated in the oxidation system. The Fe-Nx group formed by the chelation of Fe(III) with the N atom of g-C₃N₄ is the crucial active site of the Fe-C₃N₄ composite. Based on this bond, not only electrons can be quickly transferred from H₂O₂ to Fe(III) initiating the Fenton-like process, but also the leaching of Fe ions can be prevented, benefiting the eco-friendliness of the reaction. Because of its high efficiency and stability, the proposed Fe-C₃N₄ Fenton-like process provides a promising way for actual wastewater treatment.