Electroactive bimetallic CoNi and CNT modified carbon felt cathode promotes microbial CO₂ electroreduction

Area of Science:

• Electrochemistry and Microbial Electrosynthesis
• Materials Science for Energy Applications
• Biotechnology and Sustainable Chemistry

Background:

• Microbial electrosynthesis (MES) systems efficiently convert carbon dioxide (CO2) to valuable organic chemicals.
• The performance of MES is critically dependent on the electrochemical properties of electrode materials.
• Developing advanced electrode materials is key to enhancing CO2 reduction efficiency in MES.

Purpose of the Study:

• To improve the efficiency of CO2 reduction to acetic and formic acids in MES.
• To investigate the synergistic effects of co-modifying carbon felt (CF) cathodes with nickel-cobalt bimetallic oxide (NiCo2O4) and carbon nanotubes (CNT).
• To evaluate the performance of the modified electrodes coupled with an enriched microbial community.

Main Methods:

• Fabrication of a carbon felt (CF) cathode co-modified with NiCo2O4 and CNT.
• Coupling the modified cathode with an enriched mixed microbial community from anaerobic sludge.
• Measuring acetate and formate yields and concentrations over an 8-day period.

Main Results:

• The CNT-NiCo2O4/CF cathode significantly increased acetate yield by 1.3- to 2.3-fold and formate yield by 1.1- to 2.4-fold compared to NiCo2O4/CF and CF cathodes.
• The system achieved high product concentrations: 742.98 mg/L acetate and 566.37 mg/L formate within 8 days.
• Performance gains were attributed to synergistic effects, enhanced hydrophilicity, improved microbe-electrode interactions, and boosted conductivity.

Conclusions:

• Co-modification of CF cathodes with CNT and NiCo2O4 is an effective strategy for enhancing MES performance.
• The developed electrode material promotes efficient CO2 conversion to acetic and formic acids.
• This approach offers a viable technical pathway towards carbon neutrality and sustainable chemical production.