Hydrated manganese oxide as a counter-electrode material for an electrochromic optical switching device

Abstract Thin films of hydrated manganese oxide were electrodeposited out of a base solution onto conductive SnO 2 : F glass. When cycled in a 1 M KOH solution, these films show the ability to reversibly store ions of dissociated water, however they show phase instability upon longer cycling. X-ray photoelectron spectroscopy was employed to investigate the chemical composition of the manganese oxide films. Our results indicate that hydrated MnO 2 is the composition of the film in the oxidized state. Very low coloration was noted in these films making them useful for transparent counter-electrodes. As indicated by voltammetry, the switching voltage and ion-storage capacity fit the electrochromic switching of nickel oxide, undergoing a similar reaction. Because of its properties, manganese oxide, once stabilized, may serve as a counter-electrode for an electrochromic nickel oxide device.