Identification of highly active surface iron sites on Ni(OOH) for the oxygen evolution reaction by atomic layer deposition

Jon Baker, Joel R. Schneider, Camila de Paula, Adriaan Mackus, Stacey Bent

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

Atomic layer deposition (ALD) has become a versatile tool in catalysis, allowing for precise synthesis of catalysts useful for gaining fundamental understanding of complex systems. In this work, ALD was used to perform surface-directed modification of Ni(OH)2/Ni(OOH) electrocatalysts for the oxygen evolution reaction (OER) to elucidate the different roles of iron as a surface dopant and of iron distributed throughout the NiOOH structure. Electrochemical and material characterization of FeOx ALD-modified Ni(OH)2 indicates that iron is deposited on the surface of Ni(OH)2 sheets without modifying its bulk properties. Sub-monolayer amounts of iron were deposited on the surface of Ni(OH)2 using low cycle numbers of ALD. This surface iron results in high OER activity, characteristic of Ni-Fe(OOH) catalysts. Ni(OH)2/Ni(OOH) catalysts modified to incorporate iron throughout the structure were prepared by depositing large cycle numbers of FeOx ALD, which results in the deposition of a Fe2O3 overlayer. Corrosion of this Fe2O3 overlayer during electrochemical cycling in alkaline electrolyte leads to the incorporation of iron throughout the structure of Ni(OH)2/Ni(OOH) while leaving some iron at the surface. Incorporation of iron throughout the Ni(OH)2/Ni(OOH) structure was found to increase OER geometric activity for thick, high surface area Ni(OH)2/Ni(OOH) catalysts. Lastly, Ni-FeOx electrocatalysts synthesized fully by ALD were investigated for the OER; these catalysts demonstrated high OER activity and potential for photocatalysis applications.
Original languageEnglish (US)
Pages (from-to)476-485
JournalJournal of Catalysis
Volume394
DOIs
StatePublished - Feb 1 2021
Externally publishedYes

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