3D pore-matched PANI@CNT bioanode for efficient electron extraction from toluene

Microbial fuel cell (MFC) can harvest chemical energy stored in volatile organic compounds (VOCs) and consequently are of great potential for waste gas treatment and energy recovery. However, the inadequate connection between active cells and bioanode substrate hinders the extracellular electron transfer, especially in the upper layer of biofilm, resulting in restricted degradation capacity and power output. Herein, we propose a pore matching strategy to establish electron transfer nanowires around individual cells by embedding them separately inside a pore-matched sponge (core-shell polyaniline @ carbon nanotube, PANI@CNT). The resulting MFC for toluene degradation presents 4.41 times increase in power density (279.91 mW m−2), 2.64 times increase in coulombic efficiency (18.13%), and 2.02 times increase in toluene degradation activity (0.77 h−1), which also possesses considerable advantages over literature results. Furthermore, metagenomic analysis indicates that the genes for transmembrane and extracellular electron transfer are down-regulated, validating the effectiveness of the PANI@CNT nanowires linking individual cells with bioanode substrate. These findings reveal the feasibility of the pore matching strategy to boost toluene degradation and power extraction in MFC, and give an in-depth insight into transmembrane and extracellular electron transfer mechanisms. [Display omitted] •A novel pore matching strategy for superior bioelectrode design was proposed.•Microbial cells were embedded inside a pore-matched PANI@CNT sponge.•Most microbial cells in the whole biofilm were wired with electrode substrate.•Pore-matched bioanode possessed excellent power density and coulombic efficiency.•Metagenomic result revealed transmembrane and extracellular electron transfer routes.