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

• Anodization of Ti-substrate for obtaining TiO2 nanotubes.
• Layer-by-layer deposition of Ag3PO4 crystals onto nanotubes.
• Electrochemical proton intercalation/deintercalation into the TiO2–Ag3PO4 nano-structures.
• Exhibits a strong electrochromic color contrast.

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 TiO2–Ag3PO4 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 TiO2 nanotube with and without decoration of Ag3PO4 crystals are studied by applying a potential pulsed combined with in situ reflectance measurement of the color contrast response. The deposition of Ag3PO4 crystals has exhibited an enhanced color contrast of the nanotubes. Among various samples, the amorphous nanotubes decorated uniformly with Ag3PO4 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 TiO2 nanotubes and the Ag3PO4 deposits.

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