Speciation and Electronic Structure of La1-xSrxCoO3-δ During Oxygen Electrolysis
[1];
[5];
[6]
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Oregon State Univ., Corvallis, OR (United States)
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Research Lab. for Electronics; Nanyang Technological Univ. (Singapore)
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Research Lab. for Electronics
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. Additionally, 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. Furthermore, 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.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Laboratory Directed Research and Development (LDRD) Program; Masdar Institute
- Grant/Contract Number:
- AC02-05CH11231; 69319; 02/MI/MIT/CP/11/07633/GEN/G/00
- OSTI ID:
- 1656481
- Journal Information:
- Topics in Catalysis, Vol. 61, Issue 20; ISSN 1022-5528
- Publisher:
- SpringerCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Tuning the Electronic Structure of LaNiO 3 through Alloying with Strontium to Enhance Oxygen Evolution Activity
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journal | August 2019 |
Enhanced Stability and Thickness‐Independent Oxygen Evolution Electrocatalysis of Heterostructured Anodes with Buried Epitaxial Bilayers
|
journal | June 2019 |
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