Dual-metal sites for the control over reactive oxygen species generation: singlet oxygen and hydroxyl radical.

The monotonous reaction pathway dominated by free radicals leads to unsatisfying catalyst reusability, weak anti-interference capacity against complex environmental matrices, and limited degradation efficiency. Moreover, the regulation of reactive oxygen species (ROS) generation remains a fundamental bottleneck, especially for heterogeneous electro-Fenton systems. Herein, a self-supported CoFe-NC@CA-NF integrated electrode with dual active sites immobilized on nickel foam via carbon aerogel coating was constructed. Relying on a dual-metal sites, the electrode catalyzes in-situ H2O2 derived from two-electron oxygen reduction reaction, driving the concurrent generation of singlet oxygen (1O2) and hydroxyl radical (•OH) as dual ROS. Based on experimental and theoretical analysis, Fe coordination in CoFe-NC@CA-NF optimizes the electronic structure of Co site and the adsorption energies of intermediates, thus promoting the generation of both radicals and nonradicals. Notably, the CoFe-NC@CA-NF system achieved the complete degradation of sulfamethoxazole (SMX) within 120 min. Moreover, the catalytic electrode maintained superior performance across a broad pH range (3-11) and against various recalcitrant organic pollutants, demonstrating remarkable anti-interference property and great application prospect. This work proposes an electronic-structure engineering strategy to construct a durable bimetallic synergistic effect. Such a strategy enables the rational design of high-performance electro-Fenton cathodes and overcomes the inherent activity-selectivity trade-off of reactive oxygen species, paving a facile route toward efficient and eco-friendly water remediation.