In Situ Observation of Active Oxygen Species in Fe-Containing Ni-Based Oxygen Evolution Catalysts: The Effect of pH on Electrochemical Activity
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- 25 November 2015
- journal article
- research article
- Published by American Chemical Society (ACS) in Journal of the American Chemical Society
- Vol. 137 (48), 15112-15121
- https://doi.org/10.1021/jacs.5b06814
Abstract
Ni-based oxygen evolution catalysts (OECs) are cost-effective and very active materials that can be potentially used for efficient solar-to-fuel conversion process toward sustainable energy generation. We present a systematic spectroelectrochemical characterization of two Fe-containing Ni-based OECs, namely nickel borate (Ni(Fe)−Bi) and nickel oxyhydroxide (Ni(Fe)OOH). Our Raman and X-ray absorption spectroscopy results show that both OECs are chemically similar, and that the borate anions do not play an apparent role in the catalytic process at pH 13. Furthermore, we show spectroscopic evidence for the generation of negatively charged sites in both OECs (NiOO–), which can be described as adsorbed “active oxygen”. Our data conclusively links the OER activity of the Ni-based OECs with the generation of those sites on the surface of the OECs. The OER activity of both OECs is strongly pH dependent, which can be attributed to a deprotonation process of the Ni-based OECs, leading to the formation of the negatively charged surface sites that act as OER precursors. This work emphasizes the relevance of the electrolyte effect to obtain catalytically active phases in Ni-based OECs, in addition to the key role of the Fe impurities. This effect should be carefully considered in the development of Ni-based compounds meant to catalyze the OER at moderate pHs. Complementarily, UV–vis spectroscopy measurements show strong darkening of those catalysts in the catalytically active state. This coloration effect is directly related to the oxidation of nickel and can be an important factor limiting the efficiency of solar-driven devices utilizing Ni-based OECs.Funding Information
- Stichting voor Fundamenteel Onderzoek der Materie (FOM-03)
- Nederlandse Organisatie voor Wetenschappelijk Onderzoek
- Biosolar Cells
This publication has 55 references indexed in Scilit:
- Amorphous nickel hydroxide nanospheres with ultrahigh capacitance and energy density as electrochemical pseudocapacitor materialsNature Communications, 2013
- Mechanistic Studies of the Oxygen Evolution Reaction Mediated by a Nickel–Borate Thin Film ElectrocatalystJournal of the American Chemical Society, 2013
- Thermodynamic theory of multi-electron transfer reactions: Implications for electrocatalysisJournal of Electroanalytical Chemistry, 2011
- Nickel-borate oxygen-evolving catalyst that functions under benign conditionsProceedings of the National Academy of Sciences of the United States of America, 2010
- Metal–dioxygen and metal–dinitrogen complexes: where are the electrons?Dalton Transactions, 2010
- Implementation of a combined SAXS/WAXS/QEXAFS set-up for time-resolvedin situexperimentsJournal of Synchrotron Radiation, 2008
- Powering the planet: Chemical challenges in solar energy utilizationProceedings of the National Academy of Sciences of the United States of America, 2006
- In-situ spectroscopic studies of electrochromic hydrated nickel oxide filmsSolar Energy Materials, 1989
- Electrocatalysis in the anodic evolution of oxygen and chlorineElectrochimica Acta, 1984
- Vibrational spectra of complex borates—II. B(OH)4−-ion in teepleite, Raman spectrum and normal coordinate analysisSpectrochimica Acta Part A: Molecular Spectroscopy, 1974