Re-evaluating the Contribution of a Fe-Based Current Collector to Bioelectrochemical Methanogenesis: Role and...

Area of Science:

• Bioelectrochemical systems
• Microbial electrosynthesis
• Renewable energy and sustainability

Background:

• Metal-based current collectors are crucial for electron delivery in microbial electrosynthesis (MES) cathodes.
• The impact of current collector corrosion on biofilm formation and electromethanogenesis has been largely unexamined.

Purpose of the Study:

• To investigate the effects of iron (Fe)-based current collector corrosion on CO2 electromethanogenesis in MES.
• To elucidate the mechanisms by which Fe corrosion products enhance microbial activity and methane production.

Main Methods:

• Utilized microbial electrosynthesis (MES) cells with and without Fe-based current collectors (Bio FeCF vs. Bio CF).
• Performed electrochemical analysis to study electron transfer and catalytic properties.
• Analyzed biofilm composition and gene expression related to extracellular electron uptake in methanogens.

Main Results:

• In situ corrosion of the Fe current collector decorated the cathode, significantly improving CO2 electromethanogenesis.
• MES startup time was reduced by over two-thirds, and methane (CH4) production rate increased 3.5-fold.
• Fe deposits acted as electron shuttles and H2 production catalysts, reducing methanogen reliance on electroactive bacteria (EABs) and increasing extracellular electron uptake gene abundance.

Conclusions:

• Corroded Fe-based current collectors play multiple beneficial roles in enhancing CO2 electromethanogenesis.
• Fe corrosion products facilitate direct electron transfer to methanogens, boosting overall system performance.
• This finding offers a novel strategy for optimizing microbial electrosynthesis processes for methane production.