Extraordinary Stability of IrO2(110) Ultrathin Films Supported on TiO2(110) under Cathodic Polarization

• DOI: 10.1021/acs.jpclett.0c02730
• Publication Date: 2020-10-13T02:09:16Z
• Authors: Tim Weber; Vedran Vonk; Marcel J. S. Abb; Jonas Evertsson; Martina Sandroni; Jakub Drnec; Andreas Stierle; Edvin Lundgren; Herbert Over
• Keywords: Pourbaix diagram

Down to a cathodic potentials of −1.20 V versus the reversible hydrogen electrode, structure IrO2(110) electrodes supported by TiO2(110) is found be stable in situ synchrotron-based X-ray diffraction. Such high should lead reduction metallic Ir (Pourbaix diagram). From IrO2 lattice parameters, determined during polarization H2SO4 electrolyte solution (pH 0.4), it estimated that unit cell volume increases 1% due likely proton incorporation, which lack significant swelling film derived from reflectivity experiments. Ex photoelectron spectroscopy suggests protons are incorporated into below −1.0 V, although remains exclusively IV+ oxidation state down V. Obviously, further hydrogenation oxygen toward water suppressed for kinetic reasons and hints at rate-determining chemical step cannot controlled electrode potential.