Improving the Biocompatibility and Energy Performance of a Microbial Bioanode with Black Phosphorus and Polypyrrole Nanocomposites

Abstract When it comes to enhancing the way bioelectrochemical systems perform, improving how microorganisms and electrodes interact remains challenging. Here, we have modified anodes to improve the performance of microbial fuel cells (MFCs). Specifically, we modified a graphite plate anode (GP) by using three strategies─electroactivation (EGP), electroactivation followed by black phosphorus incorporation (EGP/BP), and subsequent EGP/BP electropolymerization with polypyrrole (EGP/BP/PPy)─and evaluated EGP, EGP/BP, and EGP/BP/PPy in dual-chamber MFCs. The MFC anodic biofilm was formed from mangrove sediment in sodium acetate. Scanning electron microscopy confirmed that the modification strategies modified the GP surface and that a robust biofilm emerged after each treatment. The highly modified EGP/BP/PPy performed the best and reached a maximum voltage of 530.0 ± 35 mV, compared to 100.0 ± 18 mV and 10.8 ± 2 mV achieved with EGP/BP and EGP, respectively. EGP/BP/PPy also provided the highest maximum power density and Coulombic charge. Modifying the GP surface influenced the bacterial community composition. The genus Alcaligenes predominated under all the tested conditions, but other electroactive genera such as Pseudomonas and Geobacter emerged in EGP/BP/PPy. Therefore, combining BP and PPy to functionalize GP provided a stable and conductive electroactive biofilm, which enhanced bacterial adhesion, electron transfer, and energy generation. This work highlights that synergistic electrode functionalization improves electrode conductivity and microbial activity, which paves the way for advanced biohybrid electrochemical systems to be designed.