Enhanced electricity generation and energy storage in a microbial fuel cell with a bimetallic-modified capacitive anode

Microbial fuel cells (MFCs) are energy conversion devices that utilize microorganisms attached to the electrode as catalysts for the oxidation of organic waste, thereby generating electricity. In this study, a two-step hydro- thermal method was employed to prepare a CF/NiO/Fe3O4 capacitive composite anode by directly growing NiO on a carbon felt substrate as a metal framework to support the in-situ growth of Fe3O4. In this paper, electrochemical tests such as cyclic voltammetry and AC impedance were used to investigate the electrochemical performance of the modified anode. The two electrodes were characterized by SEM, EDS, XRD, FTIR, BET, TEM and SAED test. The MFCs with the CF/NiO/Fe3O4 anode exhibited significant improvements in generation of power and storage of energy performance, reaching a maximum power density of 9.29 W/m3, which has increased by 1.54-fold compared to CF/NiO anode. After charging/discharging for 60 min, the CF/NiO/Fe3O4 anode had a sum charge of 8532.07C /m2, which was a significant increase of 1868.82C/m2 compared to the CF/ NiO anode. High-throughput sequencing analysis suggested that the proportion of electricity-generating microorganisms on the CF/NiO/Fe3O4 surface of the anode reached 86.03 %, which was higher than that on CF/ NiO anode surface. The protein contents of the CF/NiO/Fe3O4 reached 71.03 mg/cm3. The application of capacitive materials in MFCs would allow the constructed MFCs to generate and store bioelectricity simultaneously.