Comparative study of Co<sub>3</sub>O<sub>4</sub>(111), CoFe<sub>2</sub>O<sub>4</sub>(111), and Fe<sub>3</sub>O<sub>4</sub>(111) thin film electrocatalysts for the oxygen evolution reaction.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 37553328.
- Also identified by DOI 10.1038/s41467-023-40461-0 and PMC identifier 10409724.
- Licence recorded as CC BY.
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Abstract
Water electrolysis to produce 'green H<sub>2</sub>' with renewable energy is a promising option for the upcoming green economy. However, the slow and complex oxygen evolution reaction at the anode limits the efficiency. Co<sub>3</sub>O<sub>4</sub> with added iron is a capable catalyst for this reaction, but the role of iron is presently unclear. To investigate this topic, we compare epitaxial Co<sub>3</sub>O<sub>4</sub>(111), CoFe<sub>2</sub>O<sub>4</sub>(111), and Fe<sub>3</sub>O<sub>4</sub>(111) thin film model electrocatalysts, combining quasi in-situ preparation and characterization in ultra-high vacuum with electrochemistry experiments. The well-defined composition and structure of the thin epitaxial films permits the obtention of quantitatively comparable results. CoFe<sub>2</sub>O<sub>4</sub>(111) is found to be up to about four times more active than Co<sub>3</sub>O<sub>4</sub>(111) and about nine times more than Fe<sub>3</sub>O<sub>4</sub>(111), with the activity depending acutely on the Co/Fe concentration ratio. Under reaction conditions, all three oxides are covered by oxyhydroxide. For CoFe<sub>2</sub>O<sub>4</sub>(111), the oxyhydroxide's Fe/Co concentration ratio is stabilized by partial iron dissolution.