Non-radical revolution: Fe–Co dual-atom/N-C catalysts unlocking singlet oxygen-dominated antibiotic degradation

The efficient degradation of antibiotics in wastewater is critical for addressing global water pollution challenges. Herein, we report a dual-atom Fe-Co catalyst anchored on a nitrogen-doped carbon matrix (FeCo/NC), which demonstrates superior performance in peroxymonosulfate (PMS) activation and tetracycline (TC) degradation. This system achieves a remarkable 91.2% TC removal efficiency, significantly outperforming single-atom catalysts. Mechanistic investigations reveal that FeCo/NC induces a unique spin-state reconstruction, optimizing its electronic structure and shifting the oxidative mechanism from a radical-driven pathway to a singlet oxygen (¹O₂)-dominated nonradical process. Theoretical insights from density functional theory (DFT) calculations confirm the preferred ¹O₂ generation pathway at FeCo active sites, with reduced energy barriers that enhance catalytic activity. Toxicological evaluations validate that TC degradation intermediates exhibit minimal ecological risks, reinforcing the environmental safety of this approach. The long-term stability of the FeCo/NC/PMS system was evaluated via a continuous-flow photocatalytic reactor, the above results reflect the superior catalytic activity and stability of the FeCo/NC/PMS system. This work establishes a paradigm for designing advanced dual-atom catalysts and provides critical insights for developing eco-friendly solutions to antibiotic-contaminated wastewater treatment.