Boosting bioelectricity generation using three-dimensional nitrogen-doped macroporous carbons as freestanding anode

Microbial fuel cells (MFCs) have been shown as a promising technology for sustainable energy production and wastewater treatment. However, the still relatively insignificant power generation and high costs of MFCs limit its large-scale application. Herein, we report a facile and low-cost route to construct nitrogen-doped 3D macroporous carbon (NPVP-RFC) via pyrolysis of self-assembled structure of cross-linked resorcinol–formaldehyde resin (RF), polyvinyl pyrrolidone (PVP) and dicyandiamide (DCDA). The as-prepared NPVP-RFC material provides a large specific surface area for high-density loading of bacteria. Moreover, the incorporation of active N species into carbon frameworks offers a hydrophilic surface with good electrolyte wettability and increased conductivity for promoting biofilm adhesion and enhancing extracellular electron transfer (EET) process, thus enabling a high-power output. Thus, the NPVP-RFC MFCs achieve fast start-up time of 2.9 days and maximum volumetric power density of 9.23 W/m3 at 21.48 A/m3. Notably, the NPVP-RFC MFCs show good and stable performance for beer brewery wastewater treatment, achieving a maximum volumetric power density of 6.38 W/m3, chemical oxygen demand (COD) removal efficiency of 84.83%, and a columbic efficiency of 35.57%. This work provides a facile and low-cost synthesis technique for fabricating high-performance MFC anodes for use in microbial energy harvesting.