title: PTFE effect on the electrocatalysis of the oxygen reduction reaction in membraneless microbial fuel cells.
abstract: Influence of PTFE in the external Gas Diffusion Layer (GDL) of open-air cathodes applied to membraneless microbial fuel cells (MFCs) is investigated in this work. Electrochemical measurements on cathodes with different PTFE contents (200%, 100%, 80% and 60%) were carried out to characterize cathodic oxygen reduction reaction, to study the reaction kinetics. It is demonstrated that ORR is not under diffusion-limiting conditions in the tested systems. Based on cyclic voltammetry, an increase of the cathodic electrochemical active area took place with the decrease of PTFE content. This was not directly related to MFC productivity, but to the cathode wettability and the biocathode development. Low electrodic interface resistances (from 1 to 1.5 Ω at the start, to near 0.1 Ω at day 61) indicated a negligible ohmic drop. A decrease of the Tafel slopes from 120 to 80 mV during productive periods of MFCs followed the biological activity in the whole MFC system. A high PTFE content in the cathode showed a detrimental effect on the MFC productivity, acting as an inhibitor of ORR electrocatalysis in the triple contact zone.
authors.affiliation: Università degli Studi di Milano, Department of Chemistry, Via Golgi 19, 20133 Milan, Italy.
authors.forename: Edoardo
authors.initials: E
authors.lastname: Guerrini
authors.affiliation: Politecnico di Milano, Department of Chemistry, Materials and Chemical Engineering, Piazza Leonardo da Vinci 32, 20133 Milan, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Grattieri
authors.affiliation: Università degli Studi di Milano, Department of Chemistry, Via Golgi 19, 20133 Milan, Italy.
authors.forename: Alessio
authors.initials: A
authors.lastname: Faggianelli
authors.affiliation: Ricerca Sul Sistema Energetico SpA, Department of Sustainable Development and Energy Sources, V. Rubattino, 54, 20134 Milan, Italy. Electronic address: pierangela.cristiani@rse-web.it.
authors.forename: Pierangela
authors.initials: P
authors.lastname: Cristiani
authors.affiliation: Università degli Studi di Milano, Department of Chemistry, Via Golgi 19, 20133 Milan, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Trasatti
mesh_terms: D001674:Bioelectric Energy Sources; D002384:Catalysis; D025802:Electric Capacitance; D004553:Electric Conductivity; D004563:Electrochemistry; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D011138:Polytetrafluoroethylene / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D011138:Polytetrafluoroethylene; D010100:Oxygen
keywords: Biocathode; Gas Diffusion Layer; Microbial fuel cells; Oxygen reduction; PTFE