Hierarchical modulation of extracellular electron transfer processes in microbial fuel cell anodes for enhanced power output through improved Geobacter adhesion

•Garlic-derived 3D free-standing anode is highly conductive and easy to fabricate.•The carbonized anode demonstrated impressive power output and efficiency.•Both direct electron transfer and mediated electron transfer are enhanced.•Carbonized garlic anode can load more biomass and enrich more Geobacter. Although microbial fuel cell (MFC) technology is nearing practical realization, the challenge of attaining higher power output continues to impede its widespread implementation. In this study, we successfully developed free-standing three-dimensional high-performance anode materials for MFCs using a straightforward "one-step" process based on garlic. The resulting anode not only promotes the accumulation of biomass and the enrichment of exoelectrogen Geobacter but also facilitates interfacial extracellular electron transfer. This led to rapid start-up within just three days, a robust power density of 12.37 W/m3, and an impressive 24.04 % coulombic efficiency in mixed-culture MFC reactors. Our investigation into the underlying mechanisms of exocellular electron transfer revealed improvements in both direct electron transfer and mediated electron transfer processes. Notably, the fabrication of carbonized garlic MFC anodes proves to be technically competitive and economically relevant. It not only paves the way for the development of high-performance MFCs but also provides valuable insights for the rational design of materials related to microbial electrochemical technologies. [Display omitted]