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Detection of high-valent iron species in alloyed oxidic cobaltates for catalysing the oxygen evolution reaction.

ABSTRACT: Iron alloying of oxidic cobaltate catalysts results in catalytic activity for oxygen evolution on par with Ni-Fe oxides in base but at much higher alloying compositions. Zero-field ⁵⁷Fe Mössbauer spectroscopy and X-ray absorption spectroscopy (XAS) are able to clearly identify Fe⁴⁺ in mixed-metal Co-Fe oxides. The highest Fe⁴⁺ population is obtained in the 40-60% Fe alloying range, and XAS identifies the ion residing in an octahedral oxide ligand field. The oxygen evolution reaction (OER) activity, as reflected in Tafel analysis of CoFeO_x films in 1 M KOH, tracks the absolute concentration of Fe⁴⁺. The results reported herein suggest an important role for the formation of the Fe⁴⁺ redox state in activating cobaltate OER catalysts at high iron loadings.

SUBMITTER: Li N

PROVIDER: S-EPMC8270959 | biostudies-literature | 2021 Jul

REPOSITORIES: biostudies-literature

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Detection of high-valent iron species in alloyed oxidic cobaltates for catalysing the oxygen evolution reaction.

Li Nancy N Hadt Ryan G RG Hayes Dugan D Chen Lin X LX Nocera Daniel G DG

Nature communications 20210709 1

Iron alloying of oxidic cobaltate catalysts results in catalytic activity for oxygen evolution on par with Ni-Fe oxides in base but at much higher alloying compositions. Zero-field 57Fe Mössbauer spectroscopy and X-ray absorption spectroscopy (XAS) are able to clearly identify Fe4+ in mixed-metal Co-Fe oxides. The highest Fe4+ population is obtained in the 40-60% Fe alloying range, and XAS identifies the ion residing in an octahedral oxide ligand field. The oxyge ...[more]

PMID: 34244515

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