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Exploring the Limits of Self-Repair in Cobalt Oxide Films for Electrocatalytic Water Oxidation

  • Mohammad Reza Mohammadi
    Mohammad Reza Mohammadi
    Department of Physics, University of Sistan and Baluchestan, Zahedan 98167-45845, Iran
  • Stefan Loos
    Stefan Loos
    Department for Experimental Physics, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
    More by Stefan Loos
  • Petko Chernev
    Petko Chernev
    Department for Experimental Physics, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
  • Chiara Pasquini
    Chiara Pasquini
    Department for Experimental Physics, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
  • Ivelina Zaharieva
    Ivelina Zaharieva
    Department for Experimental Physics, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
  • Diego González-Flores
    Diego González-Flores
    Department for Experimental Physics, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
  • Paul Kubella
    Paul Kubella
    Department for Experimental Physics, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
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  • Katharina Klingan
    Katharina Klingan
    Department for Experimental Physics, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
  • Rodney D. L. Smith*
    Rodney D. L. Smith
    Department of Chemistry, University of Waterloo, 200 University Ave. W, Waterloo, Ontario N2L 3G1,Canada
    *Email: [email protected]
  • , and 
  • Holger Dau*
    Holger Dau
    Department for Experimental Physics, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
    *Email: [email protected]
    More by Holger Dau
Cite this: ACS Catal. 2020, 10, 14, 7990–7999
Publication Date (Web):June 26, 2020
https://doi.org/10.1021/acscatal.0c01944
Copyright © 2020 American Chemical Society
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Abstract

We analyze the stability of anodically electrodeposited cobalt hydroxide films during operation as electrocatalysts for water oxidation and show that the stability considerations of these films are a complex issue concerning multiple distinct phenomena. We combine the electrochemical analysis with the quantitative analysis of cobalt content using X-ray fluorescence spectroscopy, transient behavior analysis using in operando XANES electrochemical analysis, and structural analysis using cryogenic X-ray absorption spectroscopy to show that three distinct behavioral regimes exist. Each behavioral regime suffers from a degree of corrosion, but both self-healing and self-repair mechanisms are capable of partially stabilizing the cobalt content within the catalyst film. However, even if the absolute cobalt content of the film is fully stabilized, the catalytic behavior of the film degrades over time. This behavior is attributed to observed structural evolution of the material, where mid- and long-range structural order increases during operation. The increased structural order appears independent of whether self-healing or self-repair mechanisms are activated and results in fundamental changes in the catalytic behavior, observable as decreased turnover frequency and increased Tafel slopes. These results reveal that the cobalt content or electrocatalytic performance of the catalyst films can be stabilized by controlling the applied voltage or solution composition, but simultaneous stabilization of both is not currently possible.

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The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acscatal.0c01944.

  • EXAFS simulations, voltage-dependent UV–visible absorption spectra, tables of values for data normalization, temporal electrochemical stability plots, cobalt content determined by XRF and electrochemistry, steady-state electron transfer behavior, fitted parameters for oxidation and reduction kinetics, values for EXAFS coordination shell simulations, and scanning electron micrographs (PDF)

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Cited By


This article is cited by 3 publications.

  1. Biswajit Mondal, Samir Chattopadhyay, Subal Dey, Atif Mahammed, Kaustuv Mittra, Atanu Rana, Zeev Gross, Abhishek Dey. Elucidation of Factors That Govern the 2e–/2H+ vs 4e–/4H+ Selectivity of Water Oxidation by a Cobalt Corrole. Journal of the American Chemical Society 2020, 142 (50) , 21040-21049. https://doi.org/10.1021/jacs.0c08654
  2. Chiara Pasquini, Si Liu, Petko Chernev, Diego Gonzalez-Flores, Mohammad Reza Mohammadi, Paul Kubella, Shan Jiang, Stefan Loos, Katharina Klingan, Vadim Sikolenko, Stefan Mebs, Michael Haumann, Paul Beyer, Luca D’Amario, Rodney D. L. Smith, Ivelina Zaharieva, Holger Dau. Operando tracking of oxidation-state changes by coupling electrochemistry with time-resolved X-ray absorption spectroscopy demonstrated for water oxidation by a cobalt-based catalyst film. Analytical and Bioanalytical Chemistry 2021, 413 (21) , 5395-5408. https://doi.org/10.1007/s00216-021-03515-0
  3. J. Niklas Hausmann, Rodrigo Beltrán‐Suito, Stefan Mebs, Viktor Hlukhyy, Thomas F. Fässler, Holger Dau, Matthias Driess, Prashanth W. Menezes. Evolving Highly Active Oxidic Iron(III) Phase from Corrosion of Intermetallic Iron Silicide to Master Efficient Electrocatalytic Water Oxidation and Selective Oxygenation of 5‐Hydroxymethylfurfural. Advanced Materials 2021, 33 (27) , 2008823. https://doi.org/10.1002/adma.202008823