Iridium Oxohydroxide, a Significant Member in the Family of Iridium Oxides. Stoichiometry, Characterization, and Implications in Bioelectrodes

Iridium oxohydroxide thin coatings have been prepared by a dynamic oxidation electrodeposition method from complex oxalate solutions that induce template effects in the final coating at the nanoscale. The preparation method induces the formation of a oxohydroxide with reproducible stoichiometry and sponge-like quasiamorphous open structure, high ionic mobility, and significant behavior as compared with other reported iridium oxides as derived from X-ray diffraction, XPS, and TGA. Reproducible mixed valence states are also observed and a local rutile structure that allows ion exchange and facile redox changes. Rather significant is the large affinity for organic compounds observed and the behavior as substrate for cell culture, the best observed to date. Optimal cell response seems to be related to such open structure, which suggests this coating as ideal for devices implanted in the nervous system.