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Modes of Fe Incorporation in Co–Fe (Oxy)hydroxide Oxygen Evolution Electrocatalysts
Author(s) -
Zhang Ting,
Nellist Michael R.,
Enman Lisa J.,
Xiang Junhui,
Boettcher Shan W.
Publication year - 2019
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201801975
Subject(s) - oxygen evolution , hydroxide , oxygen , electrocatalyst , catalysis , inorganic chemistry , chemistry , oxygen reduction , materials science , chemical engineering , electrochemistry , electrode , organic chemistry , engineering
Ni–Fe (oxy)hydroxide and Co–Fe (oxy)hydroxide are among the most active oxygen evolution reaction (OER) catalysts in alkaline media. Fe is essential for the high activity, but the details of how Fe is incorporated into the Ni or Co (oxy)hydroxide structure and affects catalysis remain incompletely understood. This study concerns two different modes of Fe incorporation to form Co(Fe)O x H y , which both yield increased OER activity but result in Fe and Co species that differ in chemical reactivity and electrochemical response. Co(Fe)O x H y films that were cathodically deposited from mixed Co and Fe nitrate solution (co‐deposited) result in Fe species that interact strongly with the Co species (as evidenced by an anodic shift in the Co redox wave) and are difficult to leach out under electrochemical conditions. Fe incorporated into a CoO x H y film by cycling in Fe‐spiked KOH electrolyte similarly enhance activity, but do not strongly electronically interact with the majority of the Co in the film and are removed by cycling in Fe‐free KOH. These results support the hypothesis that co‐deposition of Co(Fe)O x H y leads to films where the Co and Fe are mixed within the nanosheet structure and cycling in Fe‐spiked KOH incorporates Fe species largely at surface, edge, or defect sites, where they drive OER but do not otherwise significantly modulate the electrochemical response of the Co.