Improving power output in microbial fuel cells with free-standing CoCx/Co@CC composite anodes

Microbial fuel cells (MFCs) are being recognized as a promising solution for sustainable energy generation and wastewater treatment. Despite their potential, MFCs face certain challenges that must be overcome, such as the problem of low power output caused by inefficient extracellular electron transfer (EET). In this study, we develop a nanoporous CoCx/Co@CC composite anode using microwave-assisted and high-temperature calcination methods to enhance EET efficiency and bacterial adhesion in MFCs. Compared with pure carbon cloth (CC) anodes, MFCs with CoCx/Co@CC anodes exhibit a 1.24-fold increase in power density, with a maximum output of 2693 mW m−2. The improved performance can be attributed to the lower charge transfer resistance (Rct) and higher redox activity of the CoCx/Co@CC anode. Cobalt's multiple valence states enhance its ability to transfer electrons between microorganisms and electrodes, ultimately increasing the overall redox activity. The CoCx/Co@CC anode also promotes the growth and enrichment of exoelectrogens, with Geobacter being enriched up to 75 % at the anode, compared with 46 % at the CC electrode. These findings demonstrate the potential of CoCx/Co@CC anodes for improving the EET efficiency of MFCs, which can have significant implications for sustainable energy and wastewater treatment.