In situ study of electrochromic properties of self-assembled TiO2 nanotubes

Electrochromical properties of anodic self-assembled nanotubes were investigated. It was found that amorphous titania nanotubes were able to insert H+ ions in a highly reversible manner. Coloration of the TiO2 nanotubes occurred at potentials below −0.5 V vs. Ag/AgCl in 1M (NH4)2SO4 aqueous solution. The proton insertion reaction probably leads to the formation of a Ti3+/Ti4+ solid solution in the amorphous titania electrode, as was shown by the analysis of the derivative curve. The nanotubular titania electrode shows reasonable color efficiency when compared with other electrochromic materials and it is a promising candidate for the fabrication of low-cost interdigitated electrochromic devices.