3D Macroporous Nitrogen-Enriched Graphitic Carbon Scaffold for Efficient Bioelectricity Generation in Microbial Fuel Cells

Microbial fuel cell (MFC) can generate electricity based on oxidation of organic compounds by exoelectogens, giving rise to a promising potential for recovering electrical energy from organic wastewater. The structure and property of anode materials have inherent impact to extracellular electron transfer (EET), an interfacial process that greatly limits bioelectricity production of MFC. Herein, a three dimensional (3D) macroporous nitrogen-enriched graphitic carbon (NGC) scaffold is fabricated from commercially available melamine foam using facile pyrolysis method. The NGC electrode is demonstrated to promote EET efficiently, achieving a power density of 750 mW m⁻² based on pure cultured Shewanella oneidensis MR-1 in acetate-feeding MFC. The unique 3D open-cell structure not only offers habitats for colonization of electroactive biofilm up to a maximal density but also provides macroporous architecture for internal mass transfer without concern of bio-blocking and bio-fouling. Additionally, nitrogen incorporation also plays a significant role in enhancing EET, where pyrrolic nitrogen is much more active than graphitic and pyridinic nitrogen as indicated by density functional theory calculation. This work provides a proof-of-concept demonstration of a high-efficiency, cost-effective, easily scaling-up, and environmentally friendly anode material of bioelectrochemical systems for electricity generation, hydrogen production, and pollutant degradation.