Tracking high-valent surface iron species in the oxygen evolution reaction on cobalt iron (oxy)hydroxides
Journal
Energy and Environmental Science
Journal Volume
15
Journal Issue
1
Pages
206-214
Date Issued
2022
Author(s)
Abstract
The oxygen evolution reaction (OER) is the bottleneck reaction of water splitting, which can be used to generate green hydrogen from renewable electricity. Cobalt iron oxyhydroxides (CoFeOxHy) are among the most active OER catalysts in alkaline medium. However, the active sites of these catalysts remain unclear. Here we use operando ultraviolet-visible (UV-Vis), X-ray absorption, and Raman spectroscopy to reveal oxidations of both Fe and Co ions in CoFeOxHy during the OER. By analyzing samples with different Fe contents and thickness, we find that the concentration of Fe4+ species at the surface, but not the concentration of Co4+ in the bulk, scales with the catalytic activity. These results indicate an Fe4+-containing active site in CoFeOxHy. This journal is ? The Royal Society of Chemistry.
Subjects
Cobalt compounds
Iron compounds
Oxygen
X ray absorption
Active oxygen
Active site
Alkaline media
Fe and Co
Iron species
Operando
Oxyhydroxides
Renewable electricity
Water splitting
]+ catalyst
Catalyst activity
chemical reaction
concentration (composition)
detection method
hydroxide
intertidal environment
iron
SDGs
Type
journal article