Phase-Controlled Multi-Element Oxide-Sulfide Heterostructure Toward High-Efficiency Electro-Fenton Oxidation

Electron Fenton (EF) degradation often suffers from low in situ H₂O₂ electrosynthesis and Fe²⁺ regeneration. Herein, a novel multi-element oxide-sulfide heterostructure is reported, (FeVCoCuMn)₂O₃/(CuFeVCoMn)S, for efficient and stable EF degradation. The oxide-sulfide phase ratio is optimized through temperature control during the synthesis. Experimental data and theoretical calculations highlight the advantages of multi-metal doping in enhancing the H₂O₂ selectivity and Fe²⁺ regeneration. The multi-element oxide-sulfide heterostructure outperforms its subsystems by providing enhanced H₂O₂ electrosynthesis. Among the elements, the Cu, Co, Mn, V, and S donate electrons to the trivalent Fe³⁺ cations, thus enhancing the Fe²⁺ regeneration. Density functional theory calculations show that the characteristics of the heterostructure can be optimized based on the phase ratio, resulting in enhanced charge transfer and optimized intermediate binding strength. The (FeVCoCuMn)₂O₃/(CuFeVCoMn)S catalyst achieves 98% tetracycline degradation in 120 min and maintains 87% efficiency over ten cycles. This work provides an insight into the coexistence of multi-metal doping and heterostructure in obtaining an efficient and selective heterogeneous EF catalyst for wastewater treatment.