A new strategy for improving MFC power output by shared electrode MFC–MEC coupling

Considering the lower power output of microbial fuel cell (MFC), this study explored a new MFC coupled with a microbial electrolysis cell (MEC) system (MFC−MEC) to effectively promote extracellular electron transfer (EET) and consequently enhance MFC power output. Based on the principle of electric field superposition, we constructed a system of shared anode (SA-MFC-MEC) and cathode (SC-MFC-MEC) configurations between the MFC and MEC. In this system, the MEC provides an exogenous electric field (EEF) that strengthens its internal electric field, thereby enhancing the electrochemical properties of the anode biofilm. Our results demonstrated that the EEF effectively increased the electrochemical activity of the MFC anode biofilm, leading to the formation of more electrochemically active sites and thicker biofilms at the anode, resulting in increased power output. The SA−MFC−MEC system exhibited optimal performance, achieving a maximum power density of 120.9 mW/m2 and an EET rate constant of 1.9 × 10−5 cm/s, which were 2.17 and 2.4 times higher than the control R−MFC, respectively. These findings confirm that an EEF significantly contributes to the EET and is key to enhancing MFC power output. Additionally, the SA−MFC−MEC facilitated methane recovery through the independent operation of the MFC and MEC cathodes, with a gas production performance comparable to the control R−MEC. This study not only provides a deeper understanding of biofilm electrochemical behavior in an EEF environment but also demonstrates the potential of the MFC−MEC system in energy recovery applications.