Enhancing Extracellular Electron Transfer with a Novel Carbonized Balsa Wood-Carbon Nanotubes Composite Anode

Driven by the principles of sustainable chemistry and engineering, the present study aims to develop a high-performance anode material for microbial fuel cells (MFCs) using a combination of biomass-derived carbon and nanomaterials. Anode modification is considered key to improving the performance of MFCs because the anode is where microorganisms inhabit, metabolize, and produce electricity. The power density of MFCs is limited due to the inability of noncapacitive anodes to store electrons generated by bacteria in a timely manner. This study combines nanomaterials with biomass macroporous carbon materials to prepare hierarchically porous three-dimensional carbon materials (FeCNTs@CW) and then uses electrochemical methods to activate the materials (A-FeCNTs@CW) to increase the hydrophilicity and capacitance of the materials. The hierarchical porous structure facilitates microbial adhesion, Fe and N-doped carbon nanotubes promote the extraction and transfer of electrons, and the redox effect of Fe³⁺/Fe²⁺ favors electron storage. The MFCs equipped with A-FeCNTs@CW anodes achieved a cumulative charge of 0.189 C/cm² after 10 min of charging and discharging and a power density of 3.394 W/cm², significantly improving electron utilization and power density, outperforming previously reported anodes. Additionally, the enrichment rate of Geobacter by A-FeCNTs@CW reached 85%. These findings highlight the potential of A-FeCNTs@CW to advance MFC performance by simultaneously optimizing electron storage and transfer, offering new directions for the design and development of next-generation MFC anodes.