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dc.contributor.authorLYONS, MICHAELen
dc.contributor.authorGODWIN, IANen
dc.date.accessioned2012-06-18T13:52:44Z
dc.date.available2012-06-18T13:52:44Z
dc.date.issued2012en
dc.date.submitted2012en
dc.identifier.citationMichael E G Lyons, Lisa Russell, Maria O'Brien. Richard L Doyle, Michael P Brandon, Redox switching and oxygen evolution at hydrous oxyhydroxide modified nickel electrodes in aqueous alkaline solution: effect of hydrous oxide thickness and base concentration, International Journal of Electrochemical Science, 7, 4, 2012, 2710 - 2763en
dc.identifier.otherYen
dc.identifier.urihttp://hdl.handle.net/2262/63763
dc.descriptionPUBLISHEDen
dc.description.abstractOutstanding issues regarding the film formation, the redox switching reaction and the oxygen evolution reaction (OER) electrocatalytic behaviour of multi-cycled nickel oxy-hydroxide films in aqueous alkaline solution have been discussed. The oxide is grown using a repetitive potential multi-cycling technique, and the mechanism of the latter hydrous oxide formation process has been discussed. A duplex layer model of the oxide/solution interphase region is proposed. The acid/base behaviour of the hydrous oxide and the microdispersed nature of the latter material has been emphasized. The hydrous oxide is considered as a porous assembly of interlinked octahedrally coordinated anionic metal oxyhydroxide surfaquo complexes which form an open network structure. The latter contains considerable quantities of water molecules which facilitate hydroxide ion discharge at the metal site during active oxygen evolution, and also charge compensating cations. The dynamics of redox switching has been quantified in terms of a diffusive frequency via analysis of the cyclic voltammetry response as a function of potential sweep rate using the Laviron-Aoki electron hopping diffusion model by analogy with redox polymer modified electrodes. Potential step chronoamperometry applied to hydrous oxide coated Ni surfaces has indicated that the Ni(II)/Ni(III) redox switching reaction is quite complex. Steady state Tafel plot analysis has been used to elucidate the kinetics and mechanism of oxygen evolution. Tafel slope values of ca. 60 mVdec-1 and ca. 120 mVdec-1 are found at low and high overpotentials respectively, whereas the reaction order with respect to hydroxide ion activity remains invariant at ca. 1.0 as the potential is increased. These observations are rationalized in terms of a kinetic scheme involving Langmuir adsorption and the formation of a physisorbed hydrogen peroxide intermediate on the oxide surface. The dual Tafel slope behaviour is ascribed to the changeover in rate determining step from the second chemical hydroxide ion reorganization step to the first initial discharge step as the potential is increased, which is in contrast to the potential dependence of the surface coverage of adsorbed intermediates which holds for hydrous iron oxide electrodes in base.en
dc.description.sponsorshipScience Foundation Ireland SFI/10/IN.1/I2969en
dc.format.extent2710en
dc.format.extent2763en
dc.language.isoenen
dc.relation.ispartofseriesInternational Journal of Electrochemical Scienceen
dc.relation.ispartofseries7en
dc.relation.ispartofseries4en
dc.rightsYen
dc.subjectElectrochemical water splittingen
dc.subjectnickel oxyhydroxide filmen
dc.subjectoxygen evolution electrocatalysisen
dc.subjectelectrodesen
dc.subjectHydrous Oxide Thicknessen
dc.titleRedox switching and oxygen evolution at hydrous oxyhydroxide modified nickel electrodes in aqueous alkaline solution: effect of hydrous oxide thickness and base concentrationen
dc.typeJournal Articleen
dc.contributor.sponsorScience Foundation Ireland (SFI)en
dc.type.supercollectionscholarly_publicationsen
dc.type.supercollectionrefereed_publicationsen
dc.identifier.peoplefinderurlhttp://people.tcd.ie/melyonsen
dc.identifier.peoplefinderurlhttp://people.tcd.ie/igodwinen
dc.identifier.rssinternalid76216en
dc.contributor.sponsorGrantNumberSFI/10/IN.1/I2969en
dc.subject.TCDThemeNanoscience & Materialsen
dc.subject.TCDThemeSmart & Sustainable Planeten
dc.identifier.rssurihttp://www.electrochemsci.org/papers/vol7/7042710.pdfen
dc.identifier.rssurihttp://www.electrochemsci.org/papers/vol7/7042710.pdfen
dc.identifier.orcid_id0000-0002-0320-7547en


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