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Reversible perovskite electrocatalysts for oxygen reduction/oxygen evolution

Reversible perovskite electrocatalysts for oxygen reduction/oxygen evolution
Reversible perovskite electrocatalysts for oxygen reduction/oxygen evolution
The identification of electrocatalysts mediating both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are prerequisite for the development of reversible fuel cells and rechargeable metal–air batteries. The question remains as to whether a bifunctional catalyst, or a single catalyst site, will exhibit potentials converging to +1.23 VRHE. Transition metal-based perovskites provide tunable catalysts where site substitution can influence both ORR and OER, however substitution in the pseudobinary phases results in an anti-correlation in ORR and OER activities. We reveal that LaxMnyNi1-yO3-δ, compositions with lanthanum A-site sub-stoichiometry exhibit reversible activity correlating with the appearance of the Mn3+/Mn4+ redox couple. The Mn3+/Mn4+ couple is associated with Mn4+ co-existing with Mn3+ in the bulk, as La3+ is substituted by Ni2+ at the A-site to create a mixed valent system. We also show that a direct A-site substitution by the Ca2+ cation in LaxCa1-xMnyO3-δ perovskites also results in the creation of Mn4+, the appearance of the Mn3+/Mn4+ redox couple, and a concomitant reversible activity. These results highlight a general strategy of optimizing oxide electrocatalysts with reversible activity.
1478-6524
4609-4617
Bradley, Keiren
ba9cb0f8-d308-4055-b2f9-627f94cec25f
Giagloglou, Kyriakos
5660d1e1-466c-48e1-991d-a7fa403729db
Hayden, Brian E.
aea74f68-2264-4487-9d84-5b12ddbbb331
Jungius, Hugo
8bc1efaa-b2fc-4820-9c38-ac0aa34ea113
Vian, Chris
7da679ef-2ba2-43f1-9bfd-554eb8613d04
Bradley, Keiren
ba9cb0f8-d308-4055-b2f9-627f94cec25f
Giagloglou, Kyriakos
5660d1e1-466c-48e1-991d-a7fa403729db
Hayden, Brian E.
aea74f68-2264-4487-9d84-5b12ddbbb331
Jungius, Hugo
8bc1efaa-b2fc-4820-9c38-ac0aa34ea113
Vian, Chris
7da679ef-2ba2-43f1-9bfd-554eb8613d04

Bradley, Keiren, Giagloglou, Kyriakos, Hayden, Brian E., Jungius, Hugo and Vian, Chris (2019) Reversible perovskite electrocatalysts for oxygen reduction/oxygen evolution. Chemical Science, 10 (17), 4609-4617. (doi:10.1039/c9sc00412b).

Record type: Article

Abstract

The identification of electrocatalysts mediating both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are prerequisite for the development of reversible fuel cells and rechargeable metal–air batteries. The question remains as to whether a bifunctional catalyst, or a single catalyst site, will exhibit potentials converging to +1.23 VRHE. Transition metal-based perovskites provide tunable catalysts where site substitution can influence both ORR and OER, however substitution in the pseudobinary phases results in an anti-correlation in ORR and OER activities. We reveal that LaxMnyNi1-yO3-δ, compositions with lanthanum A-site sub-stoichiometry exhibit reversible activity correlating with the appearance of the Mn3+/Mn4+ redox couple. The Mn3+/Mn4+ couple is associated with Mn4+ co-existing with Mn3+ in the bulk, as La3+ is substituted by Ni2+ at the A-site to create a mixed valent system. We also show that a direct A-site substitution by the Ca2+ cation in LaxCa1-xMnyO3-δ perovskites also results in the creation of Mn4+, the appearance of the Mn3+/Mn4+ redox couple, and a concomitant reversible activity. These results highlight a general strategy of optimizing oxide electrocatalysts with reversible activity.

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2019 - Chemical Science - Version of Record
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Accepted/In Press date: 19 March 2019
e-pub ahead of print date: 19 March 2019
Published date: 7 May 2019

Identifiers

Local EPrints ID: 430768
URI: http://eprints.soton.ac.uk/id/eprint/430768
ISSN: 1478-6524
PURE UUID: 9c4d3af4-670b-4b79-bd02-d4df6c07729f
ORCID for Brian E. Hayden: ORCID iD orcid.org/0000-0002-7762-1812

Catalogue record

Date deposited: 10 May 2019 16:30
Last modified: 26 Nov 2021 02:33

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Contributors

Author: Keiren Bradley
Author: Kyriakos Giagloglou
Author: Brian E. Hayden ORCID iD
Author: Hugo Jungius
Author: Chris Vian

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