Speciation and electronic structure of La1−xSrxCoO3−δ during oxygen electrolysis
Cobalt-containing perovskite oxides are promising electrocatalysts for the oxygen evolution reaction (OER) in alkaline electrolyzers. However, a lack of fundamental understanding of oxide surfaces impedes rational catalyst design for improved activity and stability. We couple electrochemical studies...
| Main Authors: | , , , , , , , , , |
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| Format: | Journal Article |
| Language: | English |
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2020
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| Online Access: | https://hdl.handle.net/10356/139661 |
| _version_ | 1826127639819059200 |
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| author | Stoerzinger, Kelsey A. Wang, Renshaw Xiao Hwang, Jonathan Rao, Reshma R. Hong, Wesley T. Rouleau, C. M. Lee, Dongwook Yu, Yi Crumlin, Ethan J. Shao-Horn, Yang |
| author2 | School of Electrical and Electronic Engineering |
| author_facet | School of Electrical and Electronic Engineering Stoerzinger, Kelsey A. Wang, Renshaw Xiao Hwang, Jonathan Rao, Reshma R. Hong, Wesley T. Rouleau, C. M. Lee, Dongwook Yu, Yi Crumlin, Ethan J. Shao-Horn, Yang |
| author_sort | Stoerzinger, Kelsey A. |
| collection | NTU |
| description | Cobalt-containing perovskite oxides are promising electrocatalysts for the oxygen evolution reaction (OER) in alkaline electrolyzers. However, a lack of fundamental understanding of oxide surfaces impedes rational catalyst design for improved activity and stability. We couple electrochemical studies of epitaxial La1−xSrxCoO3−δ films with in situ and operando ambient pressure X-ray photoelectron spectroscopy to investigate the surface stoichiometry, adsorbates, and electronic structure. In situ investigations spanning electrode compositions in a humid environment indicate that hydroxyl and carbonate affinity increase with Sr content, leading to an increase in binding energy of metal core levels and the valence band edge from the formation of a surface dipole. The maximum in hydroxylation at 40% Sr is commensurate with the highest OER activity, where activity scales with greater hole carrier concentration and mobility. Operando measurements of the 20% Sr-doped oxide in alkaline electrolyte indicate that the surface stoichiometry remains constant during OER, supporting the idea that the oxide electrocatalyst is stable and behaves as a metal, with the voltage drop confined to the electrolyte. Furthermore, hydroxyl and carbonate species are present on the electrode surface even under oxidizing conditions, and may impact the availability of active sites or the binding strength of adsorbed intermediates via adsorbate–adsorbate interactions. For covalent oxides with facile charge transfer kinetics, the accumulation of hydroxyl species with oxidative potentials suggests the rate of reaction could be limited by proton transfer kinetics. This operando insight will help guide modeling of self-consistent oxide electrocatalysts, and highlights the potential importance of carbonates in oxygen electrocatalysis. |
| first_indexed | 2024-10-01T07:12:11Z |
| format | Journal Article |
| id | ntu-10356/139661 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2024-10-01T07:12:11Z |
| publishDate | 2020 |
| record_format | dspace |
| spelling | ntu-10356/1396612023-02-28T19:26:15Z Speciation and electronic structure of La1−xSrxCoO3−δ during oxygen electrolysis Stoerzinger, Kelsey A. Wang, Renshaw Xiao Hwang, Jonathan Rao, Reshma R. Hong, Wesley T. Rouleau, C. M. Lee, Dongwook Yu, Yi Crumlin, Ethan J. Shao-Horn, Yang School of Electrical and Electronic Engineering School of Physical and Mathematical Sciences Science::Chemistry Electrocatalysis Electrode-electrolyte Interface Cobalt-containing perovskite oxides are promising electrocatalysts for the oxygen evolution reaction (OER) in alkaline electrolyzers. However, a lack of fundamental understanding of oxide surfaces impedes rational catalyst design for improved activity and stability. We couple electrochemical studies of epitaxial La1−xSrxCoO3−δ films with in situ and operando ambient pressure X-ray photoelectron spectroscopy to investigate the surface stoichiometry, adsorbates, and electronic structure. In situ investigations spanning electrode compositions in a humid environment indicate that hydroxyl and carbonate affinity increase with Sr content, leading to an increase in binding energy of metal core levels and the valence band edge from the formation of a surface dipole. The maximum in hydroxylation at 40% Sr is commensurate with the highest OER activity, where activity scales with greater hole carrier concentration and mobility. Operando measurements of the 20% Sr-doped oxide in alkaline electrolyte indicate that the surface stoichiometry remains constant during OER, supporting the idea that the oxide electrocatalyst is stable and behaves as a metal, with the voltage drop confined to the electrolyte. Furthermore, hydroxyl and carbonate species are present on the electrode surface even under oxidizing conditions, and may impact the availability of active sites or the binding strength of adsorbed intermediates via adsorbate–adsorbate interactions. For covalent oxides with facile charge transfer kinetics, the accumulation of hydroxyl species with oxidative potentials suggests the rate of reaction could be limited by proton transfer kinetics. This operando insight will help guide modeling of self-consistent oxide electrocatalysts, and highlights the potential importance of carbonates in oxygen electrocatalysis. Accepted version 2020-05-21T01:05:24Z 2020-05-21T01:05:24Z 2018 Journal Article Stoerzinger, K. A., Wang, R. X., Hwang, J., Rao, R. R., Hong, W. T., Rouleau, C. M., . . ., Shao-Horn, Y. (2018). Speciation and electronic structure of La1−xSrxCoO3−δ during oxygen electrolysis. Topics in Catalysis, 61(20), 2161–2174. doi:10.1007/s11244-018-1070-7 1022-5528 https://hdl.handle.net/10356/139661 10.1007/s11244-018-1070-7 2-s2.0-85055689267 20 61 2161 2174 en Topics in Catalysis This is a post-peer-review, pre-copyedit version of an article published in Topics in Catalysis. The final authenticated version is available online at: http://dx.doi.org/10.1007/s11244-018-1070-7. application/pdf |
| spellingShingle | Science::Chemistry Electrocatalysis Electrode-electrolyte Interface Stoerzinger, Kelsey A. Wang, Renshaw Xiao Hwang, Jonathan Rao, Reshma R. Hong, Wesley T. Rouleau, C. M. Lee, Dongwook Yu, Yi Crumlin, Ethan J. Shao-Horn, Yang Speciation and electronic structure of La1−xSrxCoO3−δ during oxygen electrolysis |
| title | Speciation and electronic structure of La1−xSrxCoO3−δ during oxygen electrolysis |
| title_full | Speciation and electronic structure of La1−xSrxCoO3−δ during oxygen electrolysis |
| title_fullStr | Speciation and electronic structure of La1−xSrxCoO3−δ during oxygen electrolysis |
| title_full_unstemmed | Speciation and electronic structure of La1−xSrxCoO3−δ during oxygen electrolysis |
| title_short | Speciation and electronic structure of La1−xSrxCoO3−δ during oxygen electrolysis |
| title_sort | speciation and electronic structure of la1 xsrxcoo3 δ during oxygen electrolysis |
| topic | Science::Chemistry Electrocatalysis Electrode-electrolyte Interface |
| url | https://hdl.handle.net/10356/139661 |
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