Electrochemical protonation/de-protonation of titania nanotubes decorated with silver phosphate crystals: An enhanced electrochromic color contrast

Abstract In the present work, anodically grown self-organized titania nanotubes are decorated with silver phosphate crystals using a layer-by-layer technique from an aqueous solution containing silver and phosphate ion precursors. The TiO 2 –Ag 3 PO 4 nanostructures are characterized using field enhanced scanning electron microscopy, energy dispersive X-ray analyser, X-ray diffractometry and X-ray photoelectron spectroscopy. The electrochromic behaviours of the TiO 2 nanotube with and without decoration of Ag 3 PO 4 crystals are studied by applying a potential pulsed combined with in situ reflectance measurement of the color contrast response. The deposition of Ag 3 PO 4 crystals has exhibited an enhanced color contrast of the nanotubes. Among various samples, the amorphous nanotubes decorated uniformly with Ag 3 PO 4 crystals without blocking the tube openings has demonstrated the strongest color contrast. The experiments demonstrate that the enhanced color contrast is due to the synergetic contribution from the TiO 2 nanotubes and the Ag 3 PO 4 deposits.