A novel self-bonding 3D carbon particle bioanode derived from agricultural residue for improving the enrichment of electroactive bacteria in microbial fuel cell

Many researchers focus on regulating the structure and surface properties of electrode materials to improve their biocompatibility, promote the growth of electroactive bacteria and accelerate the efficiency of extracellular electron transfer, thus improving the performance of microbial fuel cells (MFCs). For the commonly used three-dimensional (3D) carbon-based electrode materials, it is important to explore the key factors that affect their performance as anode for the controllable customization of materials. In this study, a novel method suitable for common agricultural residue was developed to prepare self-bonding 3D spherical biochar particles with high mechanical strength after activation with sulfuric acid. The MFC with particles pyrolyzed at 900 °C as anode achieved the highest power density (2066.7 ± 7.0 mW m−2) and a higher abundance of electroactive bacteria (92.8%). Correlation analysis of environmental factors showed that the specific surface area, micropore area, total pore volume and capacitance of the material were positively correlated with the maximum power density, current density, biomass, accumulated charge of MFC and the abundance of Bacteroides, Geobacter, norank_PHOS-HE36 and Clostridium_sensu_stricto_10 on the bioanode. Desulfovibrio and Comamonas showed a higher affinity with oxygen-containing functional groups on materials. The conductivity and pore structure of 3D carbon materials were the dominant factors affecting MFC performance. The findings will provide guidance for the customized structure of 3D carbon electrode to improve the performance of MFCs.