This study presents innovative Ti1- xNb xN-Ag films obtained by a suitable combination of low-energy and high-energy sputtering leading to bacterial inactivation. The bacterial inactivation kinetics by the TiNbN layers was drastically enhanced by the addition of 6-7% Ag and proceeded to completion within 3 h after the film autoclaving. By X-ray photoelectron spectroscopy (XPS), the samples after autoclaving presented in their upper layers TiO2, Nb2O5 and Ag2O with a surface composition of Ti0.81Nb0.19N0.99Ag0.068. Surface potential/pH changes in the Ti1- xNb xN-Ag films were monitored during bacterial inactivation. Surface redox processes during the bacterial inactivation were detected by XPS. The diffusion of Ag in the Ti1- xNb xN-Ag films was followed at 50 and 70 °C pointing. The beneficial thermal treatment points out to the bifunctional bacterial inactivation properties of these films and their potential application in healthcare facilities. Interfacial charge transfer (IFCT) under light irradiation between Ag2O, Nb2O5 and TiO2 is suggested consistent with the data found during the course of this study. The TiO2/Nb2O5 lattice mechanism is discussed in the framework of the Verwey's controlled valence model. The surface properties of the Ti1- xNb xN-Ag films were investigated by X-ray diffraction, atomic force microscopy, and scanning electron microscopy.
Keywords: DCMS/HIPIMS deposition; E. coli inactivation; Nb-donor states; Ti1−xNbxN−Ag films; operating conditions; redox catalysis.