Structure and transformation of oxy-hydroxide films on Ni anodes below and above the oxygen evolution potential in alkaline electrolytes

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dc.contributor.authorMellsop, SRen_AU
dc.contributor.authorGardiner, Aen_AU
dc.contributor.authorJohannessen, Ben_AU
dc.contributor.authorMarshall, ATen_AU
dc.date.accessioned2024-12-19T21:46:31Zen_AU
dc.date.available2024-12-19T21:46:31Zen_AU
dc.date.issued2015-06-20en_AU
dc.date.statistics2024-12-11en_AU
dc.description.abstractThe anodic behaviour of a nickel electrode has been investigated in KOH electrolytes below and above the oxygen evolution potential. As the literature reports a wide range of behaviours, initial repetitive cyclic voltammetry in 1 M KOH was compared to 30 wt% KOH (i.e., that used in alkaline water electrolysers) and it was found that a process in addition to the normal α-Ni(OH)2/γ-NiOOH and β-Ni(OH)2/β-NiOOH occurs in the more concentrated electrolyte. It is also confirmed that the initial hydroxide layer formed anodically from metallic nickel is not α-Ni(OH)2, but a layer which is more readily reducible than α-Ni(OH)2. At higher potentials, while in-situ XAS suggested that γ-NiOOH is not transformed to any further phase up to 0.665 V vs HgHgO in 1 M KOH, after extensive OER (at least 40 hrs) in 30 wt% at 50 mA cm−2, an additional phase can be identified by cyclic voltammetry. Overall, during galvanostatic oxygen evolution, the nickel anodes follow an ageing behaviour characterised by a brief activation period, a short period of high activity (i.e., low overpotential) followed by deactivation and eventually stable but poor activity. While no clear evidence was obtained to identify the most active phase for oxygen evolution, it is likely that this is related to β-NiOOH and confined to the very surface of the electrode. © 2015 Elsevier Ltd.en_AU
dc.description.sponsorshipFunding for this work was provided under MSI Contract C08X1002. XPS measurements were carried out with the assistance of Dr Colin Doyle at the Research Centre of Surface and Materials Science, University of Auckland. X-ray absorption spectroscopy was undertaken on the XAS beamline at the Australian Synchrotron, Victoria, Australia.en_AU
dc.identifier.citationMellsop, S. R., Gardiner, A., Johannessen, B., & Marshall, A. T. (2015). Structure and transformation of oxy-hydroxide films on Ni anodes below and above the oxygen evolution potential in alkaline electrolytes. Electrochimica Acta, 168, 356-364. doi:10.1016/j.electacta.2015.04.020en_AU
dc.identifier.issn0013-4686en_AU
dc.identifier.journaltitleElectrochimica Actaen_AU
dc.identifier.pagination356-364en_AU
dc.identifier.urihttps://doi.org/10.1016/j.electacta.2015.04.020en_AU
dc.identifier.urihttps://apo.ansto.gov.au/handle/10238/15843en_AU
dc.identifier.volume168en_AU
dc.languageEnglishen_AU
dc.language.isoenen_AU
dc.publisherElsevieren_AU
dc.subjectTransformationsen_AU
dc.subjectFilmsen_AU
dc.subjectNickelen_AU
dc.subjectOxygenen_AU
dc.subjectEvolutionen_AU
dc.subjectHydroxidesen_AU
dc.subjectElectrodesen_AU
dc.subjectOrder-disorder transformationsen_AU
dc.subjectIonsen_AU
dc.subjectNickel hydroxidesen_AU
dc.subjectNickel oxidesen_AU
dc.subjectElectrocatalystsen_AU
dc.titleStructure and transformation of oxy-hydroxide films on Ni anodes below and above the oxygen evolution potential in alkaline electrolytesen_AU
dc.typeJournal Articleen_AU
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