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Strategies for the analysis of the metallic fraction of Ir and Ru oxides via XRD, XANES, and EXAFS

Strategies for the analysis of the metallic fraction of Ir and Ru oxides via XRD, XANES, and EXAFS
Strategies for the analysis of the metallic fraction of Ir and Ru oxides via XRD, XANES, and EXAFS
Iridium and ruthenium oxide are active electrocatalysts for oxygen evolution. The relation between preparation method, structure, and behavior of mixed oxides of iridium and ruthenium are of interest in order to obtain active and stable catalysts. In this work the structure of mixed Ru–Ir oxides synthesized by the polymeric precursor method, which involves the formation of a gel containing the metal precursors and subsequent heat-treatment in air, was studied for the IrxRu1−xO2 system. An in-depth analysis of X-ray diffraction (XRD) and X-ray absorption (XAS) data, including EXAFS and linear combination of XANES, shows that the polymeric precursor synthesis method is capable of providing an intimate mixing of Ir and Ru in the catalyst. In addition to the oxide phase, metal phases, i.e. with Ru or Ir or both in oxidation state zero (Ir(fcc) and Ru(hcp)), were also found in the product materials. Facing complex structures such as some of those synthesized here, we have shown that a representation of shells with more than one atom type are efficiently represented using mixed sites, i.e. including scattering contributions from several elements in a site corresponding to a partial occupancy of the site by these elements, this method forming a very efficient basis for analyzing EXAFS data.
1463-9076
12217-12230
Hamar Reksten, Anita
7536e96c-4a84-4deb-9495-9ec887cce78f
Russell, Andrea E.
b6b7c748-efc1-4d5d-8a7a-8e4b69396169
Richardson, Peter W.
babd5d43-0ea3-4a27-b92f-820683acd781
Thompson, Stephen
46677911-01d9-478e-ad98-87ac37cd56a6
Mathisen, Karina
aed0f945-dc58-434d-a950-95337a050b56
Seland, Frode
138bf72a-fddf-492d-9ca9-ad467f2a4ad3
Sunde, Svein
26a99ca7-aedc-4e58-ac3b-cdf865e1a53e
Hamar Reksten, Anita
7536e96c-4a84-4deb-9495-9ec887cce78f
Russell, Andrea E.
b6b7c748-efc1-4d5d-8a7a-8e4b69396169
Richardson, Peter W.
babd5d43-0ea3-4a27-b92f-820683acd781
Thompson, Stephen
46677911-01d9-478e-ad98-87ac37cd56a6
Mathisen, Karina
aed0f945-dc58-434d-a950-95337a050b56
Seland, Frode
138bf72a-fddf-492d-9ca9-ad467f2a4ad3
Sunde, Svein
26a99ca7-aedc-4e58-ac3b-cdf865e1a53e

Hamar Reksten, Anita, Russell, Andrea E., Richardson, Peter W., Thompson, Stephen, Mathisen, Karina, Seland, Frode and Sunde, Svein (2019) Strategies for the analysis of the metallic fraction of Ir and Ru oxides via XRD, XANES, and EXAFS. Physical Chemistry Chemical Physics, 2019 (21), 12217-12230. (doi:10.1039/C9CP01758E).

Record type: Article

Abstract

Iridium and ruthenium oxide are active electrocatalysts for oxygen evolution. The relation between preparation method, structure, and behavior of mixed oxides of iridium and ruthenium are of interest in order to obtain active and stable catalysts. In this work the structure of mixed Ru–Ir oxides synthesized by the polymeric precursor method, which involves the formation of a gel containing the metal precursors and subsequent heat-treatment in air, was studied for the IrxRu1−xO2 system. An in-depth analysis of X-ray diffraction (XRD) and X-ray absorption (XAS) data, including EXAFS and linear combination of XANES, shows that the polymeric precursor synthesis method is capable of providing an intimate mixing of Ir and Ru in the catalyst. In addition to the oxide phase, metal phases, i.e. with Ru or Ir or both in oxidation state zero (Ir(fcc) and Ru(hcp)), were also found in the product materials. Facing complex structures such as some of those synthesized here, we have shown that a representation of shells with more than one atom type are efficiently represented using mixed sites, i.e. including scattering contributions from several elements in a site corresponding to a partial occupancy of the site by these elements, this method forming a very efficient basis for analyzing EXAFS data.

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Accepted/In Press date: 24 May 2019
e-pub ahead of print date: 25 May 2019
Published date: 21 June 2019

Identifiers

Local EPrints ID: 432938
URI: http://eprints.soton.ac.uk/id/eprint/432938
ISSN: 1463-9076
PURE UUID: 2ac1b1fc-bf3b-4b9a-a9ed-a9124123281e
ORCID for Andrea E. Russell: ORCID iD orcid.org/0000-0002-8382-6443

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Date deposited: 01 Aug 2019 16:30
Last modified: 26 Nov 2021 06:52

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Contributors

Author: Anita Hamar Reksten
Author: Peter W. Richardson
Author: Stephen Thompson
Author: Karina Mathisen
Author: Frode Seland
Author: Svein Sunde

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