Cu-Co sulfides anchored on CNTs/NF cathode for wide-pH electro-Fenton-like degradation of tetracycline: Synergistic mechanism, stability, and eco-safety.

Electro-Fenton (EF)-like systems are emerging as promising strategies for the degradation of refractory antibiotics in water. Herein, a novel CuCoS@CNTs/NF cathode was fabricated and evaluated for tetracycline (TC) degradation. Compared with pristine NF, CNTs/NF, CuS@CNTs/NF, and CoS@CNTs/NF, the CuCoS@CNTs/NF electrode exhibited superior catalytic activity, achieving 97.7 % TC removal within 50 min with a reaction rate constant of 0.069 min-1, nearly twice that of single-metal sulfide electrodes. The enhanced activity was attributed to the synergistic effect of Cu and Co, which optimized intermediate adsorption, accelerated charge transfer, and promoted reactive oxygen species (ROS) generation. Quenching and EPR analyses confirmed the predominant roles of ·O2-, 1O2, and ·OH in the EF-like process, supported by continuous redox cycling between Cu+/Cu2+ and Co2+/Co3+. The electrode demonstrated excellent stability, retaining >90 % efficiency after 10 cycles, and exhibited broad-spectrum degradation toward carbamazepine, p-nitrophenol, Methylene Blue, and Rhodamine B. LC-MS analysis revealed multiple degradation pathways, with intermediates gradually oxidized into low-molecular-weight products. Toxicological assessment indicated significant detoxification, with reduced aquatic toxicity, mutagenicity, and phytotoxicity after treatment. These findings highlight CuCoS@CNTs/NF as a robust and versatile cathode material for EF-like applications in water remediation.