Electroactive Bimetallic CoNi and CNT Modified Carbon Felt Cathode Promotes Microbial CO2 Electroreduction.

Efficiently reducing carbon dioxide (CO2) to high-value organic chemicals in microbial electrosynthesis (MES) systems hinges on the electrochemical performance of electrode materials. This study increased the efficiency of CO2 reduction to acetic and formic acids by creating a carbon felt (CF) cathode co-modified with nickel‑cobalt bimetallic oxide (NiCo2O4) and carbon nanotubes (CNT) coupled with an enriched mixed microbial community derived from anaerobic sludge. Compared to NiCo2O4/CF and CF cathodes, the CNT-NiCo2O4/CF cathode increased acetate yield by 1.3- and 2.3-fold, and formate yield by 1.1- and 2.4-fold, respectively. Within 8 days, the system achieved 742.98 mg/L acetate and 566.37 mg/L formate. Performance gains stem from: (1) the synergistic effect of CNT and NiCo2O4, which increased electrode surface area and electron transfer efficiency; (2) enhanced hydrophilicity, which improved microbe-electrode interactions; and (3) the presence of Co/Ni ions, which boosted CF conductivity and the selective enrichment of electroactive microbes (e.g., Sporomusa and Cupidesulfovibrio). This study provides an innovative strategy for developing high-performance MES electrode materials. Through the synergistic design of bimetallic oxides and nanocarbon materials, the conversion of CO2 to acetic acid and formic acid was achieved, offering a feasible technical pathway toward carbon neutrality.