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  Phase Segregation in Cobalt Iron Oxide Nanowires toward Enhanced Oxygen Evolution Reaction Activity

Budiyanto, E., Salamon, S., Wang, Y., Wende, H., & Tüysüz, H. (2022). Phase Segregation in Cobalt Iron Oxide Nanowires toward Enhanced Oxygen Evolution Reaction Activity. JACS Au, 2(3), 697-710. doi:10.1021/jacsau.1c00561.

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Genre: Journal Article

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 Creators:
Budiyanto, Eko1, Author              
Salamon, Soma2, Author
Wang, Yue1, Author              
Wende, Heiko2, Author
Tüysüz, Harun1, Author              
Affiliations:
1Research Group Tüysüz, Max-Planck-Institut für Kohlenforschung, Max Planck Society, ou_1950290              
2Faculty of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, 47057 Duisburg, Germany, ou_persistent22              

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Free keywords: cobalt iron oxide; hard templating; electrocatalyst; oxygen evolution reaction; phase transformation; Mössbauer; in situ Raman
 Abstract: The impact of reduction post-treatment and phase segregation of cobalt iron oxide nanowires on their electrochemical oxygen evolution reaction (OER) activity is investigated. A series of cobalt iron oxide spinel nanowires are prepared via the nanocasting route using ordered mesoporous silica as a hard template. The replicated oxides are selectively reduced through a mild reduction that results in phase transformation as well as the formation of grain boundaries. The detailed structural analyses, including the 57Fe isotope-enriched Mössbauer study, validated the formation of iron oxide clusters supported by ordered mesoporous CoO nanowires after the reduction process. This affects the OER activity significantly, whereby the overpotential at 10 mA/cm2 decreases from 378 to 339 mV and the current density at 1.7 V vs RHE increases by twofold from 150 to 315 mA/cm2. In situ Raman microscopy revealed that the surfaces of reduced CoO were oxidized to cobalt with a higher oxidation state upon solvation in the KOH electrolyte. The implementation of external potential bias led to the formation of an oxyhydroxide intermediate and a disordered-spinel phase. The interactions of iron clusters with cobalt oxide at the phase boundaries were found to be beneficial to enhance the charge transfer of the cobalt oxide and boost the overall OER activity by reaching a Faradaic efficiency of up to 96%. All in all, the post-reduction and phase segregation of cobalt iron oxide play an important role as a precatalyst for the OER.

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Language(s): eng - English
 Dates: 2021-12-152022-02-252022-03-28
 Publication Status: Published online
 Pages: 14
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Identifiers: DOI: 10.1021/jacsau.1c00561
 Degree: -

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Title: JACS Au
  Abbreviation : JACS Au
Source Genre: Journal
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Publ. Info: Washington, DC : American Chemical Society
Pages: - Volume / Issue: 2 (3) Sequence Number: - Start / End Page: 697 - 710 Identifier: ISSN: 2691-3704
CoNE: https://pure.mpg.de/cone/journals/resource/2691-3704