Two-functional DC sputtered Cu-containing TiO2 thin films

The article reports on structure, optical properties, UV-induced hydrophilicity and biocidal activity of DC sputtered Cu-containing TiO2 thin films. The TiO2/Cu films with low (≤10 at.%) Cu content were reactively sputtered from a composed Ti/Cu target in a mixture of Ar + O2 at different partial pressures of oxygen pO2pO2 on glass substrates held on floating potential Ufl. This way TiO2/Cu films with Cu homogeneously distributed in the whole volume of film were prepared. The main attention was concentrated on the effect of the amount of Cu added to TiO2 film on its crystallization, structure, optical properties and correlations between the structure and (i) the hydrophilicity and (ii) the efficiency of killing of Escherichia coli bacteria on the surface of TiO2/Cu composite film after UV irradiation. It is shown that ∼1000 nm thick TiO2/Cu composite film with ∼1.5 at.% Cu exhibits simultaneously two functions: (1) good hydrophilicity with water droplet contact angle (WDCA) α ≤ 20° and (2) strong killing power for E. coli.