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Effect of the semi-conductive properties of the passive layer on the current provided by stainless steel microbial cathodes

Pons, Liz and Délia, Marie-Line and Basséguy, Régine and Bergel, Alain Effect of the semi-conductive properties of the passive layer on the current provided by stainless steel microbial cathodes. (2011) Electrochimica Acta, vol. 56 (n° 6). pp. 2682-2688. ISSN 0013-4686

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Official URL: http://dx.doi.org/10.1016/J.ELECTACTA.2010.12.039

Abstract

Geobacter sulfur reducens biofilms were formed under constant polarisation at −0.6 V vs. Ag/AgCl on stainless steel cathodes to catalyse the reduction of fumarate. The time-evolution of the current strongly depended on the quality of the inoculum. Inoculating with young cells significantly shortened the initial lag-phase and using the same inoculum improved the reproducibility of the current–time curves. The whole set of experiments showed that 254SMO stainless steel provided higher current densities (on average 14.1 A/m2) than biofilms formed on 316L stainless steel (on average 4.5 A/m2). Biofilm coverage assessed by epifluorescent microscopy showed that coverage ratios were generally higher for 316L than for 254SMO. It must be concluded that 254SMO is more efficient in transferring electrons to bacterial cells than 316L. Mott–Schottky diagrams recorded on both materials under conditions of electrolysis in the absence of microorganisms showed that the surface oxide layers had similar n-type semi-conductive behaviour for potential values higher than the flat band potential. In contrast, 316L exhibited slight p-type behaviour at potential lower than the flat band potential, while 254SMO did not. The higher electrochemical performances of biocathodes formed on 254SMO are explained by semi-conductive properties of its passive layer, which prevented the p-type behaviour occurring in cathodic electrolysis conditions.

Item Type:Article
Additional Information:Thanks to Elsevier editor. The definitive version is available at http://www.sciencedirect.com The original PDF of the article can be found at : http://www.sciencedirect.com/science/article/pii/S0013468610016725
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT
Université de Toulouse > Université Paul Sabatier-Toulouse III - UPS
Laboratory name:
Laboratoire de Génie Chimique - LGC (Toulouse, France) - Bioprocédés et systèmes microbiens (BioSyM)
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Deposited By: Audrey LEFEVRE
Deposited On:29 Jun 2012 09:17

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