Fe-N doping boosts the performance of extracellular electron transfer from lignocellulose reconstruction-based microbe-electrode in microbial electrochemical systems

Bioanodes are critical components that influence the performance of microbial electrochemical systems (MES), and carbon-based anode materials derived from direct carbonization of biomass precursors have been intensively researched. However, the structural and functional stability of bioanodes is constrained by the type of biomass precursor. In this study, structurally controlled biomass-based electrodes were created utilizing cellulose and lignin. A number of Fe-N doping strategies were used to increase electron transfer efficiency. Although the effectiveness of anodes made from various nitrogen sources varied widely, they all increased power output, with melamine showing the greatest gain and urea being middling. This was mostly because the power was determined by a range of anode parameters that had not yet varied consistently. The Fe-N-doped samples achieved a high power density of 8163 ± 24 mW m⁻² (CL-Fe-N_C3H6N6), marking a breakthrough in biomass carbon-based electrodes. Introducing Fe-N into the electrode improved the affinity of the OM c-Cyts, considerably improving direct electron transmission. Furthermore, the Fe-N efficiently regulated the extracellular polymer, lowered the fraction of insulating polysaccharides, thereby re-reducing the charge transfer resistance from 2.9 ± 0.37 Ω (CL-0) to 1.2 ± 0.03 Ω (CL-C₃₂H₁₆FeN₈). The Fe-N-doped electrode had significantly higher biomass (3.33 ± 0.26 mg cm⁻², CL/Fe-N_CO(NH2)2) and electrogens abundance (57.1 %, CL-Fe-N_C3H6N6) compared to the unmodified anode (CL). This paper describes a simple and cost-effective method for producing high-performance carbon-based electrodes in MES.