Enhancement of oxygen evolution activity of nickel oxyhydroxide by electrolyte alkali cations
article
Herein, the effect of the alkali cation (Li+, Na+, K+, and Cs+) in alkaline electrolytes with and without Fe impurities is investigated for enhancing the activity of nickel oxyhydroxide (NiOOH) for the oxygen evolution reaction (OER). Cyclic voltammograms show that Fe impurities have a significant catalytic effect on OER activity; however, both under purified and unpurified conditions, the trend in OER activity is Cs+ > Na+ > K+ > Li+, suggesting an intrinsic cation effect of the OER activity on Fe-free Ni oxyhydroxide. In situ surface enhanced Raman spectroscopy (SERS), shows this cation dependence is related to the formation of superoxo OER intermediate (NiOO?). The electrochemically active surface area, evaluated by electrochemical impedance spectroscopy (EIS), is not influenced significantly by the cation. We postulate that the cations interact with the Ni?OO? species leading to the formation of NiOO??M+ species that is stabilized better by bigger cations (Cs+). This species would then act as the precursor to O2 evolution, explaining the higher activity.
Topics
CationsOxygen evolution reaction (OER)Catalyst activityElectrocatalysisElectrochemical impedance spectroscopyElectrolytesIron compoundsPositive ionsRaman spectroscopyAlkaline electrolytesCatalytic effectsCyclic voltammogramsElectrochemically active surface areasNickel oxyhydroxidesOxygen evolution activityOxygen evolution reactionSurface enhanced Raman spectroscopyNickel compounds
TNO Identifier
868469
ISSN
14337851
Source
Angewandte Chemie - International Edition, pp. 12999-13003.
Publisher
Wiley
Collation
5 p.
Place of publication
Weinheim, Germany
Pages
12999-13003
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