Antoine Vautier PhD defense

Présentation

**Condensed Matter and Electroactive Systems** (MaCSE) team

**Abstract** Microbial fuel cells (MFCs) convert the energy contained in organic matter into electricity, while offering potential for effluent treatment. However, their low power density limits their direct use as an energy source. Coupling MFCs with redox flow batteries (RFBs) is a strategy that allows the biological production of electricity to be separated from its storage. This thesis explores the challenges associated with this coupling and various strategies for overcoming them. The development of new electron acceptors at the MFC cathode has expanded the library of molecules that could potentially be used as negolytes in RFBs. A sulphonated phenazine (PABS) has, in particular, shown promise for direct MFC/RFB coupling, owing to its redox potential and solubility in aqueous media. An indirect coupling approach based on the biosynthesis of redox mediators, notably phenazine-1-carboxylic acid (PCA), has been investigated. This research highlights the challenges associated with the compatibility of the electrochemical and physicochemical properties of the mediators, as well as the differences in power and scale between MFCs and RFBs. It thus opens up prospects for the development of hybrid systems combining energy production, storage and effluent treatment properties.

**Jury** Christelle GAUTIER, Directrice de recherche CNRS, MOLTECH-Anjou, Université d'Angers / Examiner Mathieu ETIENNE, Directeur de recherche CNRS, LCPME, Université de Lorraine / Reviewer Estelle LEBEGUE, Maître de conférences HDR, CEISAM, Nantes Université / Reviewer Frédéric BARRIERE, Professeur des universités, ISCR, Université de Rennes / PhD Director Florence GENESTE, Directrice de recherche CNRS, ISCR, Université de Rennes / PhD Co-Director James BEHAN, Chargé de recherche CNRS, ISCR, Université de Rennes / PhD Co-Supervisor

**Invited** Charlotte BODIN, Maître de conférences, ISCR, Université de Rennes

**Contacts** Antoine VAUTIER, a.vautier14@gmail.com Frédéric BARRIERE, frederic.barriere@univ-rennes.fr Florence GENESTE, florence.geneste@univ-rennes.fr