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  Imaging the Heterogeneity of the Oxygen Evolution Reaction on Gold Electrodes Operando: Activity is Highly Local

Zwaschka, G., Nahalka, I., Marchioro, A., Tong, Y., Roke, S., & Campen, R. K. (2020). Imaging the Heterogeneity of the Oxygen Evolution Reaction on Gold Electrodes Operando: Activity is Highly Local. ACS Catalysis, 10(11), 6084-6093. doi:10.1021/acscatal.0c01177.

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 Creators:
Zwaschka, Gregor1, Author           
Nahalka, Igor2, Author
Marchioro, Arianna2, Author
Tong, Yujin1, 3, Author           
Roke, Sylvie2, Author
Campen, R. Kramer1, 3, Author           
Affiliations:
1Physical Chemistry, Fritz Haber Institute, Max Planck Society, ou_634546              
2Laboratory for fundamental BioPhotonics, Institutes of Bioengineering (IBI) and Materials Science and Engineering (IMX), School of Engineering (STI), and Lausanne Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne, Lausanne, ou_persistent22              
3Faculty of Physics, University of Duisburg-Essen, Lotharstraße 1, 47057 Duisburg, Germany, ou_persistent22              

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Free keywords: heterogeneous electrocatalysis, oxygen evolution reaction, local activity, operando active site characterization,second harmonic imaging, gold electrodes
 Abstract: Understanding the mechanism of the oxygen evolution reaction (OER), the oxidative half of electrolytic water splitting, has proven challenging. Perhaps the largest hurdle has been gaining experimental insight into the active site of the electrocatalyst used to facilitate this chemistry. Decades of study have clarified that a range of transition-metal oxides have particularly high catalytic activity for the OER. Unfortunately, for virtually all of these materials, metal oxidation and the OER occur at similar potentials. As a result, catalyst surface topography and electronic structure are expected to continuously evolve under reactive conditions. Gaining experimental insight into the OER mechanism on such materials thus requires a tool that allows spatially resolved characterization of the OER activity. In this study, we overcome this formidable experimental challenge using second harmonic microscopy and electrochemical methods to characterize the spatial heterogeneity of OER activity on polycrystalline Au working electrodes. At moderately anodic potentials, we find that the OER activity of the electrode is dominated by <1% of the surface area and that there are two types of active sites. The first is observed at potentials positive of the OER onset and is stable under potential cycling (and thus presumably extends multiple layers into the bulk gold electrode). The second occurs at potentials negative of the OER onset and is removed by potential cycling (suggesting that it involves a structural motif only 1–2 Au layers deep). This type of active site is most easily understood as the catalytically active species (hydrous oxide) in the so-called incipient hydrous oxide/adatom mediator model of electrocatalysis. Combining the ability we demonstrate here to characterize the spatial heterogeneity of OER activity with a systematic program of electrode surface structural modification offers the possibility of creating a generation of OER electrocatalysts with unusually high activity.

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Language(s): eng - English
 Dates: 2020-03-112020-04-302020-04-302020-06-05
 Publication Status: Issued
 Pages: 10
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Identifiers: DOI: 10.1021/acscatal.0c01177
 Degree: -

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Project name : SOLWET - Electron Transfer Across Solid/Liquid Interfaces: Elucidating Elementary Processes from Femtoseconds to Seconds
Grant ID : 772286
Funding program : Horizon 2020 (H2020)
Funding organization : European Commission (EC)

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Title: ACS Catalysis
  Abbreviation : ACS Catal.
Source Genre: Journal
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Publ. Info: Washington, DC : ACS
Pages: 10 Volume / Issue: 10 (11) Sequence Number: - Start / End Page: 6084 - 6093 Identifier: ISSN: 2155-5435
CoNE: https://pure.mpg.de/cone/journals/resource/2155-5435