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Boosting the Performance of Air Breathing Microbial Fuel Cells with Nanoceria

pubblicazioni - Presentazione

Boosting the Performance of Air Breathing Microbial Fuel Cells with Nanoceria

In questo lavoro, è stata dimostrata la capacità delle nanoparticelle di CeO2 e Sm-CeO2 di potenziare l’attività dei catodi microbici a base di carbonio in celle a combustibile microbiche a singola camera, respiranti aria.I risultati hanno dimostrato un aumento corrente di quasi un ordine di grandezza nel sistema di controllo drogato con nanoceramica e hanno raggiunto quasi 2 W/m2 di densità di potenza, senza alcun effetto tossico della nanoceria sul biofilm elettroattivo.

In a broader context, microbial bioelectrochemical systems promise revolutionary advantages for polluted water treatment producing electricity.Oxigen Reduction Reaction (ORR) in the biocathode is usually the kinetic limiting step for the MFC processes. The need for highly performing ORR catalysts overcoming these limitations is therefore crucial, both to enhance electricity circulation in the system and to speed pollution remediation.Among Pt alternatives, other metals, and metal oxides in particular, seem to be excellent candidates, considering the positive feedback from the experience of other closely related electrochemical technologies. However, they often could express a relevant toxicity for bacteria as well for cells of living organisms. In this work, the capability of CeO2 and Sm-CeO2 nanoparticles to enhance the activity of the most performing carbon-based microbial cathodes of air breathing single chamber MFCs was demonstrated.

The rationale for using also Sm-doped nanoceria was to decouple the effect of oxygen vacancies (oxygen storage ability) from Ce4+/3+ redox couples (direct electrocatalytic activity) on the MFC performance. To explore both ceria oxygen storage ability and direct ceria electrocatalytic activity, as well as the effect of specific surface area of the nanoparticles, three different microporous carbon cathode types were operated in MFCs: i) a nanoceria added cathode; ii) a samarium-doped ceria (Sm-CeO2) added cathode; iii) a pristine carbon activated cathode as a control.The results demonstrated current increase of almost one order of magnitude in nanoceria doped system vs control and reached almost 2 W/m2 of power density, based on the cathode geometrical surface and a chemical oxygen demand (COD) of 2.34 g L-1 in single chamber MFCs.

The presence of nanoceria is also explored in activated carbon based anodes, as well on the cathode. The results demonstrated no toxic effect of nonoceria on electroactive biofilm, guaranteeing high performance in comparison with control.

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