The A‐C Response of Iridium Oxide Films

Abstract

The dependence of the a-c response of iridium oxide films upon thickness, potential, and pH was explored in sulfuric and perchloric acid solutions. For concentrations greater than 0.1M, the response function closely resembled that for an injection process diffusively spreading from one interface throughout the film. The response time shifted by a factor of 10 5 with the potential drop across the film. A porous film model is suggested in which response is determined by the mobility of reduced lattice sites, the diffusion coefficient being controlled by a hydrogen ion exchange current within the pores. * Electrochemical Society Active Member. Key worr impedance, anodic films, electrochromism. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 132.239.1.231 Downloaded on 2015-06-02 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 132.239.1.231 Downloaded on 2015-06-02 to IP

In situ Infrared Spectroscopy of Iridium Oxide

“…The bleached state is likely to be IrOOH 9 yH20. The existence of crosslinking chains in the structure of iridium oxide have been proposed, based on the configuration of polynuclear iridium complexes with the metal ion placed at the center of edge sharing octahedra (9). Hence, tentative structures for the states comprising the electrochromic system could be represented as shown in Fig.…”

Comparison of Ir oxide film redox kinetics in sulfuric and p-toluene sulfonic acid solutions

“…EIS has also been employed previously to study electrochemically grown Ir oxide films, e.g. by Glarum et al [14] in H 2 SO 4 and HClO 4 solutions, and by Aurian-Blajeni et al [15] in H 2 SO 4 and saline solutions. The latter group suggested a particular equivalent circuit (EQC) for Ir oxide films and studied the dependence of the circuit elements on experimental variables in order to correlate them with physical and chemical components of the Ir oxide film, while Glarum and Marshall focused primarily on the interpretation of admittance plots.…”

“…The latter group suggested a particular equivalent circuit (EQC) for Ir oxide films and studied the dependence of the circuit elements on experimental variables in order to correlate them with physical and chemical components of the Ir oxide film, while Glarum and Marshall focused primarily on the interpretation of admittance plots. Both groups viewed these films as porous in nature and Glarum and Marshall [14] have speculated about the involvement of HSO 4 − as a counter ion in the Ir(+III)/(+IV) reaction.…”

Assessment of uncertainties in measurement of pH in hostile environments characteristic of nuclear repositories

“…The electrochemical behavior of acid-grown hydrous iridium oxide films are affected by: (i) the acidity of the hydrated material and the variation of this property with change in the iridium oxidation state (57); and (ii) the difference in electrical conductivity between the reduced and oxidized forms of the surface film (58,59 …”