pH dependent voltammetry of iridium oxide films.

We report studies of Anodic Iridium Oxide Films (AIROF's) and Sputtered Iridium Oxide Films (SIROF's) by voltammetric analysis and open circuit pH response. The voltage and pH dependent double injection of ions and electrons into the films is described in terms of a model of an equilibrium change in electronic Fermi level and ionic chemical potential. Electronic densities of states derived from quasi-static voltammograms indicate that AIROF's perform a pH sensitive structural transformation which is not shown by SIROF's.