Comparative evaluation of the performance of a capacitive and a non-capacitive microbial fuel cell

Electrode materials play a critical role in the performance of microbial fuel cells. This study investigates the contribution of capacitive bio-electrodes to sustainable power production in a single-chamber microbial fuel cell (MFC). The capacitive electrodes consisted of a stainless-steel wire mesh with an activated carbon layer, while the non-capacitive control electrodes were made of graphite felt with a wound current collector. The MFCs were constructed using a glass vessel with the anode completely buried in biologically active soil and the cathode placed above the soil to form a single chamber configuration. The performance of the MFCs was investigated using linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). The results showed that the performance of the capacitive MFC was three times better than that of the non-capacitive MFC. While there was no significant difference in the Ohmic resistances of the MFCs, there was a significant difference in charge transfer resistance and capacitance of the MFCs. The capacitive MFC had a double layer capacitance of $8.282\ \mu \mathrm{F}$ in addition to the diffuse layer capacitance at the layer/metal interface of 2.012 F, while the non-capacitive MFC had a double layer capacitance of $5.034\ \mu \mathrm{F}$ with no diffuse layer capacitance. The results show that the capacitive characteristics of both cathode and anode improve the performance of a single-chamber MFC.