Atom-by-atom electrodeposition of single isolated cobalt oxide molecules and clusters for studying the oxygen evolution reaction.
basic_science · Level V
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- Record sourced from PubMed, PMID 32457135.
- Also identified by DOI 10.1073/pnas.2002168117 and PMC identifier 7293634.
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Abstract
We report an electrodeposition protocol for preparing isolated cobalt oxide single molecules (Co<sub>1</sub>O<sub>x</sub>) and clusters (Co <sub><i>n</i></sub> O<sub>y</sub>) on a carbon fiber nanoelectrode. The as-prepared deposits are able to produce well-defined steady-state voltammograms for the oxygen evolution reaction (OER) in alkaline media, where the equivalent radius (<i>r</i><sub>d</sub>) is estimated by the limiting current of hydroxide oxidation in accordance with the electrocatalytic amplification model. The size of isolated clusters obtained from the femtomolar Co<sup>2+</sup> solution through an atom-by-atom technique can reach as small as 0.21 nm (<i>r</i><sub>d</sub>) which is approximately the length of Co-O bond in cobalt oxide. Therefore, the deposit was close to that of a Co<sub>1</sub>O<sub>x</sub> single molecule with only one cobalt ion, the minimum unit of the cobalt-based oxygen-evolving catalyst. Additionally, the size-dependent catalysis of the OER on Co <sub><i>n</i></sub> O<sub>y</sub> deposits shows a faster relative rate on the smaller cluster in terms of the potential at a given current density, implying the single molecular catalyst shows a superior OER activity.