Pore-Matched Sponge for Microorganisms Pushes Electron Extraction Limit in Microbial Fuel Cells

Microbial fuel cells (MFCs) are of great potential for wastewater remediation and chemical energy recovery. Nevertheless, limited by inefficient electron transfer between microorganisms and electrode, the remediation capacity and output power density of MFCs are still far away from the demand of practical application. Herein, a pore-matching strategy is reported to develop uniform electroactive biofilms by inoculating microorganisms inside a pore-matched sponge, which is assembled of core-shell polyaniline@carbon nanotube (PANI@CNT). The maximum power density achieved by the PANI@CNT bioanode is 7549.4 ± 27.6 mW m^-2 , which is higher than the excellent MFCs with proton exchange membrane reported to date, while the coulombic efficiency also attains a considerable 91.7 ± 1.2%. The PANI@CNT sponge enriches the exoelectrogen Geobacter significantly, and is proved to play the role of conductive pili in direct electron transfer as it down-regulates the gene encoding pilA. This work exemplifies a practicable strategy to develop excellent bioanode to boost electron extraction in MFCs and provides in-depth insights into the enhancement mechanism.