Vertical-Ordered Electrogenic Biofilms Engineered Through Substrate-Electric Field Synergy for Enhanced Microbial Fuel Cell Performance

Microbial fuel cell (MFC) is a novel and environmentally friendly technology for wastewater treatment and pollutant resource utilization. Although advances have been made in various aspects including electrode materials and synthetic biology approaches, the overall performance of MFC still requires improvement, with mass transfer efficiency and structural stability of biofilms emerging as key bottlenecks constraining their practical applications. This study investigated the regulation of substrate type and electrode potential during bioanode culture to optimize biofilm structure and enhance MFC performance. Results demonstrated that bioanodes cultured with glucose at −0.3 V formed vertically ordered biofilms that exhibited significant advantages in mass transfer characteristics, electrocatalytic activity, and structural stability. Under these culture conditions, enriched fermentative microorganisms facilitated the construction of porous biofilm scaffolds, while the electric field generated by the −0.3 V potential further induced vertical orientation and ordered arrangement of the biofilm. The superior mass transfer characteristics enabled the inner, middle, and outer layers of the biofilm to maintain high microbial activity (>50%), thereby maximizing the catalytic activity of electroactive microorganisms in each layer and enhancing biofilm structural stability. This study proposes a bioanode culture strategy centered on biofilm structural optimization, providing new theoretical foundations and technical pathways for achieving long-term stable and efficient MFC operation.