Electricity generation, energy storage, and microbial-community analysis in microbial fuel cells with multilayer capacitive anodes

Abstract Microbial fuel cells (MFCs) can potentially be used for power generation, but their low energy storage hinders their practical application. This study presents a novel, multilayer capacitive bioanode, modified using nitrogen-doped carbon nanotubes (N-CNT), polyaniline (PANI), and manganese dioxide (MnO2). The power-generation and energy-storage performance of MFCs containing carbon felt (CF)/N-CNT/PANI/MnO2 anodes was found to be much higher than that of traditional MFCs. The power density of an MFC with a CF/N-CNT/PANI/MnO2 bioanode (13.8 W/m3) was 2.7 times greater than that of an MFC with a bare anode (3.73 W/m3). Similarly, the exchange current density of the bioanode (0.41 A/m2) was much higher than that of the bare anode (0.06 A/m2). In chronoamperometric tests with 60 min of charging and discharging, it was observed that the stored charge of the bioanode (2492.80 C/m2) was 33 times higher than that of the bare anode (75.50 C/m2). High-throughput sequencing results showed that the CF/N-CNT/PANI/MnO2-modified bioanode exhibited high community diversity and selective enrichment of electrogenic bacteria. The dominant genera on the modified anode were electroactive bacteria, Desulfuromonas (34.39%) and Geobacter (27.93%). Therefore, MFCs with capacitive bioanodes show potential for storage and release of energy within short periods of time.