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Speciation and Electronic Structure of La1−xSrxCoO3−δ During Oxygen Electrolysis
- Source :
- Topics in Catalysis, vol 61, iss 20, Springer US
- Publication Year :
- 2018
- Publisher :
- Springer Science and Business Media LLC, 2018.
-
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.
- Subjects :
- Inorganic chemistry
Oxide
02 engineering and technology
Electrolyte
010402 general chemistry
Electrochemistry
Electrocatalyst
Physical Chemistry
01 natural sciences
Catalysis
law.invention
Ambient pressure X-ray photoelectron spectroscopy
chemistry.chemical_compound
Affordable and Clean Energy
law
Chemistry [Science]
Electrode-electrolyte Interface
Perovskite (structure)
Electrolysis
Chemistry
Oxygen evolution
General Chemistry
Chemical Engineering
021001 nanoscience & nanotechnology
Surface chemistry
0104 chemical sciences
Electrocatalysis
0210 nano-technology
Stoichiometry
Physical Chemistry (incl. Structural)
Subjects
Details
- ISSN :
- 15729028 and 10225528
- Volume :
- 61
- Database :
- OpenAIRE
- Journal :
- Topics in Catalysis
- Accession number :
- edsair.doi.dedup.....cdebdede2d903d16f6890aa9c5e375a6
- Full Text :
- https://doi.org/10.1007/s11244-018-1070-7