Nanoceria acting as oxygen reservoir for biocathodes in microbial fuel cells (original) (raw)

2019, Electrochimica Acta

High materials costs and low performance of microbial fuel cells (MFCs) are the persisting bottlenecks that significantly affect their applications. In membraneless single-chamber MFCs using carbonbased electrodes and an air-breathing cathode, bacteria play a role for both the anodic and cathodic processes. However, the microbial cathodic semi-reaction is the rate-determining step that can impair the advantage of the natural availability of oxygen in air. In this work, the microbial catalysis was improved adding cerium oxide nanoparticles (nanoceria) in carbon-based cathodes of air-breathing MFCs, boosting their performance. Two kinds of nanoparticles were tested: CeO2 and Sm-doped CeO2 (Sm-CeO2) on carbon powder, using pristine carbon powder cathodes as a control. The power generated was 113, 65 and 31 mWh m-2, for Sm-CeO2, CeO2 and control MFCs, respectively, during four subsequent fed cycles of 0.036 mol L-1 Na-acetate in carbonate buffer solution. The better performance of MFCs was correlated to the oxygen preferential and controlled entrapping and release via Ce4+/3+ redox reaction at the carbon particle surface, as well as to the increased cathode active specific surface area. The achieved results suggest that nanoceria can act as oxygen storage for bacteria in the anaerobic biofilm colonizing the cathode.

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