Enhancing air-cathode MFC performance using bio-palladium catalysts and microbial consortia

Abstract

Air-cathode microbial fuel cells (MFCs) offer a sustainable approach to bioelectricity generation, but their commercialization is hindered by costly platinum catalysts and inefficient microbial electron transfer. This study investigates bio-palladium (bio-Pd) nanoparticles as a cost-effective cathode catalyst and optimizes microbial consortia to enhance MFC performance. Four cathode configurations were tested, two incorporating bio-Pd (9.6–16.9 nm, characterized via XRD and SEM-EDS), alongside sulfate-reducing bacteria (SRB) and marine bacteria (MB) cultures. The CM3 cathode, combining bio-Pd, activated charcoal, and carbon black, achieved a peak power density of 3.70 ± 0.15 mW m⁻², six times higher than the control, with a low internal resistance of 210 ± 15 Ω m². MB, dominated by electroactive Paraclostridium sp., outperformed SRB, delivering 4.18 ± 0.17 mW m⁻² due to its dense biofilm (85% anode coverage) and efficient direct and indirect electron transfer, as confirmed by 16S rRNA sequencing and SEM. These advancements, yielding power densities comparable to bio-catalytic systems, highlight bio-Pd's potential as a sustainable alternative to platinum and Paraclostridium's role as a high-performance inoculum. Addressing South Africa's energy challenges and UN Sustainable Development Goals (6, 7, 9, 13), this work paves the way for scalable MFCs in wastewater treatment and renewable energy, though long-term stability requires further exploration.