Reactive oxygen species in iridium-based OER catalysts

Arrigo, R

Abstract

Tremendous effort has been devoted towards elucidating the fundamental reasons for the higher activity of
hydrated amorphous IrIII/IV oxyhydroxides (IrOx) in the oxygen evolution reaction (OER) in comparison with
their crystalline counterpart, rutile-type IrO2, by focusing on the metal oxidation state. Here we
demonstrate that, through an analogy to photosystem II, the nature of this reactive species is not solely
a property of the metal but is intimately tied to the electronic structure of oxygen. We use a combination
of synchrotron-based X-ray photoemission and absorption spectroscopies, ab initio calculations, and
microcalorimetry to show that holes in the O 2p states in amorphous IrOx give rise to a weakly bound
oxygen that is extremely susceptible to nucleophilic attack, reacting stoichiometrically with CO already
at room temperature. As such, we expect this species to play the critical role of the electrophilic oxygen
involved in O–O bond formation in the electrocatalytic OER on IrOx. We propose that the dynamic
nature of the Ir framework in amorphous IrOx imparts the flexibility in Ir oxidation state required for the
formation of this active electrophilic oxygen.

Citation

Arrigo, R. (2016). Reactive oxygen species in iridium-based OER catalysts. Chemical Science, 2016(7), 6791-6795. https://doi.org/10.1039/c6sc01860b

• Journal Article Type: Article
• Acceptance Date: Jul 18, 2016
• Online Publication Date: Jul 19, 2016
• Publication Date: Jul 19, 2016
• Deposit Date: Dec 4, 2018
• Publicly Available Date: Dec 4, 2018
• Journal: Chemical Science
• Print ISSN: 2041-6520
• Electronic ISSN: 2041-6539
• Publisher: Royal Society of Chemistry
• Volume: 2016
• Issue: 7
• Pages: 6791-6795
• DOI: https://doi.org/10.1039/c6sc01860b
• Publisher URL: https://doi.org/10.1039/c6sc01860b
• Related Public URLs: https://pubs.rsc.org/en/journals/journalissues/sc#!recentarticles&adv