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

Title Operando XANES from first-principles and its application to iridium oxide.
Authors F. Nattino; N. Marzari
Journal Phys Chem Chem Phys
DOI 10.1039/c9cp06726d

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.

Citation F. Nattino; N. Marzari.Operando XANES from first-principles and its application to iridium oxide.. Phys Chem Chem Phys. 2020;22(19):1080710818. doi:10.1039/c9cp06726d

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See more Iridium products. Iridium (atomic symbol: Ir, atomic number: 77) is a Block D, Group 9, Period 6 element with an atomic weight of 192.217. The number of electrons in each of iridium's shells is [2, 8, 18, 32, 15, 2] and its electron configuration is [Xe] 4f14 5d7 6s2. Iridium Bohr ModelThe iridium atom has a radius of 136 pm and a Van der Waals radius of 202 pm. Iridium was discovered and first isolated by Smithson Tennant in 1803. In its elemental form, Iridium has a silvery white appearance. Iridium is a member of the platinum group of metals.Elemental Iridium It is the most corrosion resistant metal known and is the second-densest element (after osmium). It will not react with any acid and can only be attacked by certain molten salts, such as molten sodium chloride. Iridium is found as an uncombined element and in iridium-osmium alloys. Iridium's name is derived from the Greek goddess Iris, personification of the rainbow, on account of the striking and diverse colors of its salts.

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