Spectroelectrochemical analysis of the water oxidation mechanism on doped nickel oxides
File(s)
Published version
Author(s)
Type
Journal Article
Abstract
Metal oxides and oxyhydroxides exhibit state-of-the-art activity for the oxygen evolution reaction (OER); however, their reaction mechanism, particularly the relationship between charging of the oxide and OER kinetics, remains elusive. Here, we investigate a series of Mn-, Co-, Fe-, and Zn-doped nickel oxides using operando UV–vis spectroscopy coupled with time-resolved stepped potential spectroelectrochemistry. The Ni2+/Ni3+ redox peak potential is found to shift anodically from Mn- < Co- < Fe- < Zn-doped samples, suggesting a decrease in oxygen binding energetics from Mn- to Zn-doped samples. At OER-relevant potentials, using optical absorption spectroscopy, we quantitatively detect the subsequent oxidation of these redox centers. The OER kinetics was found to have a second-order dependence on the density of these oxidized species, suggesting a chemical rate-determining step involving coupling of two oxo species. The intrinsic turnover frequency per oxidized species exhibits a volcano trend with the binding energy of oxygen on the Ni site, having a maximum activity of ∼0.05 s–1 at 300 mV overpotential for the Fe-doped sample. Consequently, we propose that for Ni centers that bind oxygen too strongly (Mn- and Co-doped oxides), OER kinetics is limited by O–O coupling and oxygen desorption, while for Ni centers that bind oxygen too weakly (Zn-doped oxides), OER kinetics is limited by the formation of oxo groups. This study not only experimentally demonstrates the relation between electroadsorption free energy and intrinsic kinetics for OER on this class of materials but also highlights the critical role of oxidized species in facilitating OER kinetics.
Date Issued
2022-05-04
Date Acceptance
2022-04-01
Citation
Journal of the American Chemical Society, 2022, 144 (17), pp.7622-7633
ISSN
0002-7863
Publisher
American Chemical Society
Start Page
7622
End Page
7633
Journal / Book Title
Journal of the American Chemical Society
Volume
144
Issue
17
Copyright Statement
© 2022 The Authors. Published by American Chemical Society. This work is published under a CC BY 4.0 International licence.
License URL
Identifier
https://www.webofscience.com/api/gateway?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000798986400017&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Subjects
Science & Technology
Physical Sciences
Chemistry, Multidisciplinary
Chemistry
OXYGEN EVOLUTION REACTION
NEAR-EDGE STRUCTURE
REDOX STATES
FE-SITES
ELECTROCATALYSTS
CATALYSIS
KINETICS
ELECTROREDUCTION
(OXY)HYDROXIDE
REDUCTION
Publication Status
Published
Date Publish Online
2022-04-20