Unveiling the synergistic mechanism of Fe-Cu bimetallic catalysts for degradation of tetracycline antibiotic with ultralow peroxymonosulfate dosage consumption: Key contribution of electron transfer process.

Developing low-oxidant, high efficiency catalysts is critical to meet the green-circular goal in water treatments. Heteroatom-doped graphite-based carbon nitride carrier catalysts are among the most promising candidate materials in water purification catalysis. In this research, a bimetallic catalyst (Fe-Cu@SNC), featuring dual reaction centers, was prepared using a mass-producible co-precipitation method. This catalyst, Fe-Cu@SNC, exhibits excellent bimetallic synergism, enabling efficient peroxymonosulfate (PMS) activation and rapid degradation of pollutants at low PMS dosage (0.1 mM). Compared to monometallic Fe@SNC and Cu@SNC, Fe-Cu@SNC achieved a 5.78-fold and 4.45-fold enhancement in the degradation rate constant (k) for tetracycline (TC), respectively. In the Fe-Cu@SNC/PMS system, the electron transfer process (ETP) plays a dominant role in the oxidation of pollutants, while the corresponding monometallic Fe@SNC or Cu@SNC is involved in both radical and non-radical processes. Additionally, possible degradation pathways for TC were proposed, and the toxicity of the intermediates was assessed through quantitative structure activity relationship (QSAR) predictions. Salt bridge experiments and dynamic adsorption and catalysis also provide new perspectives for the practical application of the catalyst.