Bioinspired FeCo Dual-Metal Phthalocyanine/Reduced Graphene Oxide Composite Anode for Enhanced Extracellular Electron Transfer in Microbial Fuel Cells

The low efficiency of extracellular electron transfer (EET) at the bioanode-electrolyte interface remains a critical bottleneck limiting power output and startup kinetics in microbial fuel cells (MFCs). To address this, we developed a biomimetic FeCo bimetallic phthalocyanine/reduced graphene oxide composite anode (FeCo-rGO@CC) inspired by the heme cofactors in cytochrome <i>c</i>. Iron phthalocyanine (FePc) and cobalt phthalocyanine (CoPc) provide atomically dispersed M-N-C active sites analogous to enzymatic centers, synergistically enhancing EET kinetics. Reduced graphene oxide (rGO) serves as a highly conductive scaffold with a large specific surface area, promoting robust electroactive biofilm formation. This integrated design yields improved performance: the FeCo-rGO@CC anode achieves a 43% faster startup (1.03 vs 1.81 days) and a 65% higher maximum power density (3.69 vs 2.23 W/m²) compared to conventional carbon cloth (CC). These significant improvements stem from the anode's ability to enhance bacterial adhesion, enrich electroactive populations, and accelerate interfacial EET. Our work elucidates that the bimetallic Fe/CoN₄ synergy not only mimics but electronically complements the function of c-Cyts, establishing a dual pathway for enhanced direct and mediated electron transfer. This bioinspired strategy of coupling precisely engineered bimetallic active sites with a conductive macroscaffold presents a versatile and effective paradigm for designing high-performance bioanodes in bioelectrochemical systems.