Nano-TiO2 film enables silver artefacts to regenerate

Nano-TiO2 films are fabricated to protect silver artefacts from discolouration and pollution during storage and appreciation. Nano-TiO2 films with five thicknesses (5, 10, 15, 20 and 25 nm) were deposited on 925 silver in atomic layer deposition (ALD). A systematical investigation was then conducted for the colour difference, transmittance, hardness and elastic modulus of the films, as well as electrochemical impedance and anti-pollution analysis. The results showed that (1) the unique metallic luster of silver artefacts can be retained in case of both the film thickness below 10 nm, and the colour difference of coated silver less than 2.5. (2) Impedance modulus of 5 nm coated silver (2.9×104 Ω cm2) at 10–2 Hz is about 5 times that of pure silver (5.5×103 Ω cm2). (3) Coated silver surface may produce hydroxyl groups and highly active radicals after coated silver exposes to visible light. The synergy of the radicals may let attached pollutants be removed from the coated surface. The influence mechanism of film thickness on silver performances is also proposed. The output of this work may offer a good avenue to protect silver artefacts and make the original beauty of silver artefacts stay safe.