Issue 19, 2020

Operando XANES from first-principles and its application to iridium oxide

Abstract

Efficient electro-catalytic water-splitting technologies require suitable catalysts for the oxygen evolution reaction (OER). The development of novel catalysts could benefit from the achievement of a complete understanding of the reaction mechanism on iridium oxide (IrO2), an active catalyst material that is, however, too scarce for large-scale applications. Considerable insight has already been provided by operando X-ray absorption near-edge structure (XANES) experiments, which paved the way towards an atomistic description of the catalyst's evolution in a working environment. We combine here first-principles simulations augmented with a continuum description of the solvent and electrolyte to investigate the electrochemical stability of various IrO2 interfaces and to predict the XANES cross-section for selected terminations under realistic conditions of applied potential. The comparison of computed O K-edge XANES spectra to corresponding experiments supports the formation of electron-deficient surface oxygen species in the OER-relevant voltage regime. Furthermore, surface hydroxyl groups that are found to be stable up to ∼1 V are suggested to be progressively oxidized at larger potentials, giving rise to a shift in the Ir L3-edge cross-section that qualitatively agrees with measurements.

Graphical abstract: Operando XANES from first-principles and its application to iridium oxide

Supplementary files

Article information

Article type
Paper
Submitted
13 dec 2019
Accepted
21 apr 2020
First published
21 apr 2020

Phys. Chem. Chem. Phys., 2020,22, 10807-10818

Operando XANES from first-principles and its application to iridium oxide

F. Nattino and N. Marzari, Phys. Chem. Chem. Phys., 2020, 22, 10807 DOI: 10.1039/C9CP06726D

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