Effect of adsorbed water vapor on Mg intercalation in electrochromic a-MoO3 films

The nature of interaction between the water vapor and MoO₃ thin films has been investigated using infrared spectroscopy technique. On prolonged exposure to high humidity conditions, presence of free water vapor and formation of Mo–OH bonds was detected in MoO₃ films. Films exposed to high humidity for various durations and freshly deposited were intercalated with Mg ions under identical experimental conditions. Free water vapor and Mo–OH bonds did not prevent/hinder the intercalation process. The diffusivity (D) of Mg ions in MoO₃ films has been estimated using Galvanostatic Intermittent Titration Technique (GITT) as a function Mg concentration. It is observed that D values are lesser in case of films exposed to humidity. Cyclic voltammetry studies carried out on films revealed reduced cyclability in exposed films compared to that of fresh films.