Influence of Pt and Au nanophases on electrochromism of WO3 in nanostructure thin-film electrodes

We report electrochromic properties of WO3 in Au–WO3 and Pt–WO3 nanostructure thin-film electrodes prepared by co-sputtering deposition method. The nanostructure electrodes consisted of Au or Pt metallic nanophase and a tungsten oxidative phase, indicating the formation of crystalline metallic nanophases in the amorphous oxide matrix. In particular, due to metallic nanophases, the modified electrochromic properties of WO3 were observed in the Au–WO3 and Pt–WO3. The nanostructure electrodes showed a reverse optical modulation with respect to applied potentials in H2SO4 solution compared to that of pure WO3 electrode. However, due to an excellent electrocatalytic activity of platinum for methanol electrooxidation at 25 °C, the electrochromism of the Pt–WO3 in contrast with that of the Au–WO3 was affected by the potentials for methanol electrooxidation in 2 M CH3OH and 0.5 M H2SO4.