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 (IrO${}_2$), an active catalyst material that is, however, too scarce for large-scale applications. Considerable insight has already been provided by \emph{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 IrO${}_2$ 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 $\sim$1 V are suggested to be progressively oxidized at larger potentials, giving rise to a shift in the Ir L${}_3$-edge cross-section that qualitatively agrees with measurements.

References in corpus (13)

• Composition, structure and stability of RuO_2(110) as a function of oxygen pressure
• Pseudopotentials for high-throughput DFT calculations
• Thermal Contraction and Disordering of the Al(110) Surface
• Steric Effects in Electrolytes: A Modified Poisson-Boltzmann Equation
• Precision and efficiency in solid-state pseudopotential calculations
• Revised self-consistent continuum solvation in electronic-structure calculations
• First-principles, atomistic thermodynamics for oxidation catalysis
• X-ray Absorption Near-Edge Structure calculations with pseudopotentials. Application to K-edge in diamond and alpha-quartz
• Bethe-Salpeter Equation Calculations of Core Excitation Spectra
• Spin-Orbit Coupling in Iridium-Based 5d Compounds Probed by X-ray Absorption Spectroscopy
• Projector augmented wave calculation of x-ray absorption spectra at the L2,3 edges
• Continuum models of the electrochemical diffuse layer in electronic-structure calculations
• Function-Space Based Solution Scheme for the Size-Modified Poisson-Boltzmann Equation in Full-Potential DFT