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Extraordinary Stability of IrO2(110) Ultrathin Films Supported on TiO2(110) under Cathodic Polarization

Weber, Tim ; Vonk, Vedran ; Abb, Marcel J.S. ; Evertsson, Jonas LU ; Sandroni, Martina ; Drnec, Jakub ; Stierle, Andreas ; Lundgren, Edvin LU and Over, Herbert (2020) In Journal of Physical Chemistry Letters p.9057-9062
Abstract

Down to a cathodic potentials of -1.20 V versus the reversible hydrogen electrode, the structure of IrO2(110) electrodes supported by TiO2(110) is found to be stable by in situ synchrotron-based X-ray diffraction. Such high cathodic potentials should lead to reduction to metallic Ir (Pourbaix diagram). From the IrO2 lattice parameters, determined during cathodic polarization in a H2SO4 electrolyte solution (pH 0.4), it is estimated that the unit cell volume increases by 1% due likely to proton incorporation, which is supported by the lack of significant swelling of the IrO2(110) film derived from X-ray reflectivity experiments. Ex situ X-ray photoelectron spectroscopy suggests that protons are incorporated into the IrO2(110) lattice... (More)

Down to a cathodic potentials of -1.20 V versus the reversible hydrogen electrode, the structure of IrO2(110) electrodes supported by TiO2(110) is found to be stable by in situ synchrotron-based X-ray diffraction. Such high cathodic potentials should lead to reduction to metallic Ir (Pourbaix diagram). From the IrO2 lattice parameters, determined during cathodic polarization in a H2SO4 electrolyte solution (pH 0.4), it is estimated that the unit cell volume increases by 1% due likely to proton incorporation, which is supported by the lack of significant swelling of the IrO2(110) film derived from X-ray reflectivity experiments. Ex situ X-ray photoelectron spectroscopy suggests that protons are incorporated into the IrO2(110) lattice below -1.0 V, although Ir remains exclusively in the IV+ oxidation state down to -1.20 V. Obviously, further hydrogenation of the lattice oxygen of IrO2(110) toward water is suppressed for kinetic reasons and hints at a rate-determining chemical step that cannot be controlled by the electrode potential.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Physical Chemistry Letters
pages
6 pages
publisher
The American Chemical Society (ACS)
external identifiers
  • pmid:33045835
  • scopus:85094664197
ISSN
1948-7185
DOI
10.1021/acs.jpclett.0c02730
language
English
LU publication?
yes
id
9022d898-25b1-4535-bd8e-c78b44570735
date added to LUP
2020-11-23 10:51:04
date last changed
2024-03-20 19:54:02
@article{9022d898-25b1-4535-bd8e-c78b44570735,
  abstract     = {{<p>Down to a cathodic potentials of -1.20 V versus the reversible hydrogen electrode, the structure of IrO2(110) electrodes supported by TiO2(110) is found to be stable by in situ synchrotron-based X-ray diffraction. Such high cathodic potentials should lead to reduction to metallic Ir (Pourbaix diagram). From the IrO2 lattice parameters, determined during cathodic polarization in a H2SO4 electrolyte solution (pH 0.4), it is estimated that the unit cell volume increases by 1% due likely to proton incorporation, which is supported by the lack of significant swelling of the IrO2(110) film derived from X-ray reflectivity experiments. Ex situ X-ray photoelectron spectroscopy suggests that protons are incorporated into the IrO2(110) lattice below -1.0 V, although Ir remains exclusively in the IV+ oxidation state down to -1.20 V. Obviously, further hydrogenation of the lattice oxygen of IrO2(110) toward water is suppressed for kinetic reasons and hints at a rate-determining chemical step that cannot be controlled by the electrode potential.</p>}},
  author       = {{Weber, Tim and Vonk, Vedran and Abb, Marcel J.S. and Evertsson, Jonas and Sandroni, Martina and Drnec, Jakub and Stierle, Andreas and Lundgren, Edvin and Over, Herbert}},
  issn         = {{1948-7185}},
  language     = {{eng}},
  pages        = {{9057--9062}},
  publisher    = {{The American Chemical Society (ACS)}},
  series       = {{Journal of Physical Chemistry Letters}},
  title        = {{Extraordinary Stability of IrO<sub>2</sub>(110) Ultrathin Films Supported on TiO<sub>2</sub>(110) under Cathodic Polarization}},
  url          = {{http://dx.doi.org/10.1021/acs.jpclett.0c02730}},
  doi          = {{10.1021/acs.jpclett.0c02730}},
  year         = {{2020}},
}