Title
Enhancement of oxygen evolution activity of nickel oxyhydroxide by electrolyte alkali cations
Author
Garcia, A.C.
Touzalin, T.
Nieuwland, C.
Perini, N.
Koper, M.T.M.
Publication year
2019
Abstract
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.
Subject
Cations
Oxygen evolution reaction (OER)
Catalyst activity
Electrocatalysis
Electrochemical impedance spectroscopy
Electrolytes
Iron compounds
Positive ions
Raman spectroscopy
Alkaline electrolytes
Catalytic effects
Cyclic voltammograms
Electrochemically active surface areas
Nickel oxyhydroxides
Oxygen evolution activity
Oxygen evolution reaction
Surface enhanced Raman spectroscopy
Nickel compounds
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DOI
https://doi.org/10.1002/anie.201905501
TNO identifier
868469
Publisher
Wiley, Weinheim, Germany
ISSN
1433-7851
Source
Angewandte Chemie - International Edition, 12999-13003
Document type
article