Co(OH)2/Mn3O4 heterojunction-modified nickel foam cathode for efficient electrocatalytic degradation of antibiotics in water via enhanced singlet oxygen generation.

Regulating electrocatalytic pathways to enhance the generation of 1O2 from ground-state oxygen is a promising but challenging strategy for the degradation of antibiotics in complex aquatic environments. Here, a nickel foam cathode modified with Co(OH)2/Mn3O4 heterojunctions (CoMn/NF) was fabricated. X-ray absorption fine structure spectroscopy and density functional theory calculations indicated that the introduction of Mn species altered the local electronic structure of the Co d-orbitals. Benefiting from interfacial electronic interactions, the CoMn/NF electrocatalytic system (CoMn/NF/EC) achieved an apparent rate constant (kobs) of 0.0561 min-1 for tetracycline (TC) degradation, which was higher than the values obtained for the Co/NF/EC (0.0301 min-1) and Mn/NF/EC (0.0335 min-1) systems. The resulting electronic modulation weakened *OOH binding and altered *OOH-related reaction pathways, thereby suppressing the conventional peroxide-mediated pathway and increasing the apparent contribution of 1O2. In situ Raman spectroscopy indicated the participation of Co sites and the dynamic evolution of oxygen-containing intermediates during electrocatalysis. Electron paramagnetic resonance and scavenger experiments indicated the concurrent involvement of ·O2-, ·OH and 1O2, with a greater apparent 1O2-associated effect in the heterojunction system. The CoMn/NF/EC system maintained effective TC removal over a pH range of 4-10 and showed tolerance to several coexisting water constituents. It also exhibited stable TC removal during 10 h of continuous-flow operation. These findings suggest that interfacial electronic modulation can regulate *OOH-related pathways and enhance1O2-mediated oxidation, providing a potential cathode-design strategy for continuous electrocatalytic water treatment.