Performance metrics and impedance spectroscopy of a surface-modified stainless-steel mesh and carbon-felt electrodes in a terrestrial microbial fuel cell for micro-power production.

Abstract

Terrestrial Microbial Fuel Cells (MFCs) represent a promising avenue for sustainable energy production, leveraging microbial metabolism to convert organic matter in the soil into electricity. Crucial to MFC performance is the selection of electrode materials, which directly interface with electroactive microbes for electron transfer. This study conducts a comparative analysis of surface-modified stainless-steel mesh (SMS) and carbon felt (CF) electrodes in terrestrial MFCs, evaluating their performance metrics and impedance spectroscopy. The SMS electrode which was fabricated using the pasting and reinforcement process demonstrated superior performance with maximum power of 859 µW compared 234 µW power of the commercially available CF electrode. This better performance of the SMS electrode was attributed to its pseudocapacitive behavior, enhancing internal charge storage capacity and overall MFC efficiency. Electrochemical impedance spectroscopy revealed a substantially higher charge transfer resistance (Rct) in the CF electrode, impeding electron transfer processes. Conversely, the SMS electrode exhibited lower charge Rct and improved diffusion characteristics, facilitating efficient electron transfer and mass transport. Notably, the Rct of the CF electrode was over 40 times higher, while its diffusion coefficient was approximately 6 times greater compared to the SMS electrode. These findings underscore the significance of tailored electrode materials in optimizing MFC performance and emphasize the utility of impedance spectroscopy in elucidating complex electrochemical processes within MFC systems, thus guiding future advancements in sustainable power production in terrestrial MFCs.