Speciation and Electronic Structure of La1−xSrxCoO3−δ During Oxygen Electrolysis
Abstract 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...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Springer US
2021
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| Online Access: | https://hdl.handle.net/1721.1/131907 |
| _version_ | 1826189929790570496 |
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| author | Stoerzinger, Kelsey A Renshaw Wang, Xiao Hwang, Jonathan Rao, Reshma R Hong, Wesley T Rouleau, C. M Lee, Dongwook Yu, Yi Crumlin, Ethan J Shao-Horn, Yang |
| author2 | Massachusetts Institute of Technology. Department of Materials Science and Engineering |
| author_facet | Massachusetts Institute of Technology. Department of Materials Science and Engineering Stoerzinger, Kelsey A Renshaw Wang, 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 | MIT |
| description | Abstract
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 | 2024-09-23T08:30:42Z |
| format | Article |
| id | mit-1721.1/131907 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T08:30:42Z |
| publishDate | 2021 |
| publisher | Springer US |
| record_format | dspace |
| spelling | mit-1721.1/1319072023-09-28T20:19:25Z Speciation and Electronic Structure of La1−xSrxCoO3−δ During Oxygen Electrolysis Stoerzinger, Kelsey A Renshaw Wang, Xiao Hwang, Jonathan Rao, Reshma R Hong, Wesley T Rouleau, C. M Lee, Dongwook Yu, Yi Crumlin, Ethan J Shao-Horn, Yang Massachusetts Institute of Technology. Department of Materials Science and Engineering Massachusetts Institute of Technology. Research Laboratory of Electronics Massachusetts Institute of Technology. Department of Mechanical Engineering Abstract 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. 2021-09-20T17:30:53Z 2021-09-20T17:30:53Z 2018-10-20 2020-09-24T21:35:08Z Article http://purl.org/eprint/type/JournalArticle https://hdl.handle.net/1721.1/131907 en https://doi.org/10.1007/s11244-018-1070-7 Creative Commons Attribution-Noncommercial-Share Alike http://creativecommons.org/licenses/by-nc-sa/4.0/ Springer Science+Business Media, LLC, part of Springer Nature application/pdf Springer US Springer US |
| spellingShingle | Stoerzinger, Kelsey A Renshaw Wang, 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 |
| url | https://hdl.handle.net/1721.1/131907 |
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