Conductive Characterization of Pseudomonas aeruginosa-Derived Nanowires for Bioelectrochemical Systems

Microbial nanowires represent a powerful natural solution for bioelectronic energy conversion, enabling long-distance extracellular electron transfer (EET) within microbial fuel cells (MFCs). In this study, nanowires produced by strain Pseudomonas aeruginosa SKVM1 were isolated, purified, and electrochemically characterized to evaluate their bifunctional electrocatalytic potential. Morphological confirmation using FESEM, EDS, and HRTEM revealed uniform filamentous structures with diameters of 10-30 nm and micrometer-scale lengths, forming a 3D entangled scaffold. Electrochemical characterization was performed by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS). CV data confirmed distinct and stable redox peaks at 0.30 and 0.27 V, indicating a cytochrome-mediated pseudocapacitance. A significant highlight of this work is the application of these nanowires in water-splitting catalysis. EIS demonstrated low charge-transfer resistance and a characteristic Warburg tail. This indicated efficient electron conduction combined with diffusion-limited ionic transport. LSV and Tafel analyses showed consistent scan-rate-dependent kinetics, with the optimal kinetic resolution occurring at 30 mV s^-1, yielding Tafel slopes (OER: 414 mV dec^-1; HER: 259 mV dec^-1). The finding suggests that the SKVM1 nanowires act as a proton wire and a biological mimic of the oxygen evolving complex (OEC), stabilizing reactive intermediates through a self-assembling protein matrix. This work advances the findings of nanowire-mediated conductivity. Future research directions include the genetic optimization of PilA subunits to enhance intrinsic conductivity and the integration of biohybrid scaffolds into MFCs and green hydrogen electrolyzers.