The electrochemistry of metallic nickel: oxides, hydroxides, hydrides and alkaline hydrogen evolution

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DOIResolve DOI: http://doi.org/10.1149/2.026303jes
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TypeArticle
Proceedings titleJournal of the Electrochemical Society
ConferenceMeeting of the Electro Chemical Society, Oct. 7-12, 2012, Honolulu, Hawaii
ISSN0013-4651
1945-7111
Volume160
Issue3
PagesF235F243
AbstractNi-based catalysts in aqueous alkaline media are low-cost electrode materials for electrolytic hydrogen generation, a renewable method of producing fuel and industrial feedstock. However, Ni cathodes show a significant decrease in their hydrogen evolution reaction (HER) activity after several hours of electrolysis. Further, industrial electrolysers are often subjected to transient anodic currents, the effects of which on Ni-based catalysts are not well-known. We consider the source of electrode deactivation and the effects of temporary anodic currents on smooth metallic Ni electrodes in alkaline solutions by cyclic voltammetry (CV), galvanostatic and potentiostatic polarization, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Polished surfaces are covered by a bilayer composed of α-Ni(OH)2 underlaid by non-stoichiometric NiOx. Below the reversible hydrogen electrode (RHE) potential, the air-formed layer mostly reduces to Ni metal and H atoms incorporate deep into the electrode material. Under industrial conditions, i.e., concentrated NaOH/KOH solutions and large cathodic current densities, α-NiHx and β-NiHx can form at the electrode surface. Above the RHE potential, NiOx, α-Ni(OH)2, β-Ni(OH)2 and β-NiOOH form reversibly and mostly reduce back to Ni on subsequent cathodic polarization. However, repeated oxidation and reduction will introduce strain on a catalyst material, which may lead to its mechanical failure.
Publication date
LanguageEnglish
AffiliationEnergy, Mining and Environment; National Research Council Canada
Peer reviewedYes
NRC number53171
NPARC number21268531
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Record identifier3f006742-0870-44ba-b328-0e7dd15cfb1f
Record created2013-09-13
Record modified2016-05-09
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