Electrochromic iridium oxide films have been investigated by a periodic reverse current method of electrodeposition using a simple apparatus.
The electrochromic iridium oxide films formed by periodic reverse current electrodeposition (PRIROF) were dependent on the chemical structure of the sulfatoiridate complex used as the electrolyte. The most desirable aspect of the chemical structure of the complex is that the sulfate ions are chelatingly coordinated to iridium atoms, and the best results were attained by heating a commercial sulfatoiridate reagent.
In electrolysis, the applied potential was reversed from +1350mV to -200mV with a period of 6 sec.
Periodic reverse electrolysis contributed to improve the uniformity and promoted the increase of the growth of iridium oxide films.
XPS analysis suggests that PRIROFs are more hydrated than anodic iridium oxide films (AIROFs).
The films showed blue-black in anodic polarization and transparent in cathodic polarization. They were chemically stable and showed good reversibility.
PRIROFs are better than sputtered iridium oxide films (SIROFs) in terms of coloring efficiency in 0.5M H₂SO₄ solution.