In-situ growth of modified Fe/Co bimetallic MOFs on carbon felt for highly efficient electro-Fenton catalysis

Heterogeneous electro-Fenton (HEF) reaction represents an environmentally sustainable strategy for the elimination of organic pollutants in wastewater. However, the efficiency of in situ electro-Fenton system is constrained by the slow conversion of Fe 3+ to Fe 2+ , insufficient production of hydrogen peroxide (H 2 O 2 ). Herein, a Fe/Co bimetallic metal-organic frameworks modified with carbon black (CB) were in situ grown on carbon felt (CF) through a facile solvothermal method, affording an integrated cathode denoted as Fe 2 /Co 1 -MOFs@CB@CF. Benefiting from the synergistic redox coupling of Fe and Co species, the as-prepared Fe 2 /Co 1 -MOFs@CF cathode exhibited accelerated Fe 3+ /Fe 2+ and Co 3+ /Co 2+ cycling, enhanced electrogeneration and activation of H 2 O 2 , and promoted production of reactive oxygen species (ROS), particularly non-radicals ( 1 O 2 ). CB after oxidation, with its high conductivity and abundant of surface oxygen-containing functional groups, which significantly enhanced the 2-electron reduction reaction (ORR) for H 2 O 2 generation. As a result, the Fe 2 /Co 1 -MOFs@CB@CF HEF system achieved 87.6% removal efficiency of tetracycline (TC) within 60 min. The integrated electrode also exhibited excellent reusability and stability, maintaining a removal efficiency of 84.2% in the fifth cycle. Mechanistic investigations revealed that the superior HEF performance originated from the combined effects of the MOF layered structure, the enhanced 2e- ORR activity of oxidized CB, and the synergistic catalysis of Fe and Co redox cycling that accelerated electron transfer. This work offers an effective strategy for constructing high-performance MOF-based cathodes and provides new insight into the development of advanced EF systems for the removal of refractory organic pollutants.