title: Multiple cathodic reaction mechanisms in seawater cathodic biofilms operating in sediment microbial fuel cells.
abstract: In this study, multiple reaction mechanisms in cathodes of sediment microbial fuel cells (SMFCs) were characterized by using cyclic voltammetry and microelectrode measurements of dissolved oxygen and pH. The cathodes were acclimated in SMFCs with sediment and seawater from San Diego Bay. Two limiting current regions were observed with onset potentials of approximately +400 mVAg/AgCl for limiting current I and -120 mVAg/AgCl for limiting current II. The appearance of two catalytic waves suggests that multiple cathodic reaction mechanisms influence cathodic performance. Microscale oxygen concentration measurements showed a zero surface concentration at the electrode surface for limiting current II but not for limiting current I, which allowed us to distinguish limiting current II as the conventional oxygen reduction reaction and limiting current I as a currently unidentified cathodic reaction mechanism. Microscale pH measurements further confirmed these results.
authors.affiliation: The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA (USA).
authors.forename: Jerome T
authors.initials: JT
authors.lastname: Babauta
authors.forename: Lewis
authors.initials: L
authors.lastname: Hsu
authors.forename: Erhan
authors.initials: E
authors.lastname: Atci
authors.forename: Jeff
authors.initials: J
authors.lastname: Kagan
authors.forename: Bart
authors.initials: B
authors.lastname: Chadwick
authors.forename: Haluk
authors.initials: H
authors.lastname: Beyenal
mesh_terms: D001674:Bioelectric Energy Sources / Q000382:microbiology*; D018441:Biofilms / Q000254:growth & development*; D002140:California; D055664:Electrochemical Techniques; D004566:Electrodes / Q000382:microbiology*; D006863:Hydrogen-Ion Concentration; D008855:Microscopy, Electron, Scanning; D010100:Oxygen / Q000032:analysis / Q000737:chemistry; D012623:Seawater / Q000737:chemistry* / Q000382:microbiology
chemical_list: D010100:Oxygen
keywords: biocathodes; cathodic biofilms; energy conversion; oxidation; sediment microbial fuel cell