title: Linking bacterial metabolism to graphite cathodes: electrochemical insights into the H(2) -producing capability of Desulfovibrio sp.
abstract: Microbial biocathodes allow converting and storing electricity produced from renewable sources in chemical fuels (e.g., H(2) ) and are, therefore, attracting considerable attention as alternative catalysts to more expensive and less available noble metals (notably Pt). Microbial biocathodes for H(2) production rely on the ability of hydrogenase-possessing microorganisms to catalyze proton reduction, with a solid electrode serving as direct electron donor. This study provides new chemical and electrochemical data on the bioelectrocatalytic activity of Desulfovibrio species. A combination of chronoamperometry, cyclic voltammetry, and impedance spectroscopy tests were used to assess the performance of the H(2) -producing microbial biocathode and to shed light on the involved electron transfer mechanisms. Cells attached onto a graphite electrode were found to catalyze H(2) production for cathode potentials more reducing than -900 mV vs. standard hydrogen electrode. The highest obtained H(2) production was 8 mmol L(-1) per day, with a Coulombic efficiency close to 100 %. The electrochemical performance of the biocathode changed over time probably due to the occurrence of enzyme activation processes induced by extended electrode polarization. Remarkably, H(2) (at least up to 20 % v/v) was not found to significantly inhibit its own production.
authors.affiliation: Department of Chemistry, Sapienza University of Rome, P.Le Aldo Moro 5, 00185 Rome, Italy. federico.aulenta@uniroma1.it
authors.forename: Federico
authors.initials: F
authors.lastname: Aulenta
authors.forename: Laura
authors.initials: L
authors.lastname: Catapano
authors.forename: Laura
authors.initials: L
authors.lastname: Snip
authors.forename: Marianna
authors.initials: M
authors.lastname: Villano
authors.forename: Mauro
authors.initials: M
authors.lastname: Majone
mesh_terms: D001674:Bioelectric Energy Sources / Q000382:microbiology*; D002384:Catalysis; D003901:Desulfovibrio / Q000378:metabolism*; D017097:Electric Impedance; D004563:Electrochemistry; D004566:Electrodes / Q000382:microbiology; D006108:Graphite; D006859:Hydrogen / Q000737:chemistry*
chemical_list: D006108:Graphite; D006859:Hydrogen