Two-functional direct current sputtered silver-containing titanium dioxide thin films

Abstract

The article reports on structure, mechanical, optical, photocatalytic and biocidal properties of Ti-Ag-O films. The Ti-Ag-O films were reactively sputter-deposited from a composed Ti/Ag target at different partial pressures of oxygen $$ pO 2 on unheated glass substrate held on floating potential U fl. It was found that addition of ∼2 at.% of Ag into TiO 2 film has no negative influence on UV-induced hydrophilicity of TiO 2 film. Thick (∼1,500 nm) TiO 2/Ag films containing (200) anatase phase exhibit the best hydrophilicity with water droplet contact angle (WDCA) lower than 10° after UV irradiation for 20 min. Thick (∼1,500 nm) TiO 2/Ag films exhibited a better UV-induced hydrophilicity compared to that of thinner (∼700 nm) TiO2/Ag films. Further it was found that hydrophilic TiO 2/Ag films exhibit a strong biocidal effect under both the visible light and the UV irradiation with 100% killing efficiency of Escherichia coli ATCC 10536 after UV irradiation for 20 min. Reported results show that single layer of TiO 2 with Ag distributed in its whole volume exhibits, after UV irradiation, simultaneously two functions: (1) excellent hydrophilicity with WDCA < 10° and (2) strong power to kill E. coli even under visible light due to direct toxicity of Ag.