Photocatalytic Activity and Antibacterial Response of Titanium Oxide Coatings Doped by Nitrogen Plasma Immersion Ion Implantation

Plasma immersion ion implantation technology has been used to enhance the photocatalytic activity of the anatase phase of TiO2 thin films deposited by cathodic arc evaporation physical vapor deposition (PVD). The main objective of this study is to shift the light absorbance of the titania to obtain antibacterial activity under visible light irradiation. TiO2 thin films, deposited on polished stainless steel AISI 304 and silicon wafers, were implanted with nitrogen ions (N+/N-2(+)) at 20 kV energy and different temperatures between 250 and 350(omicron)C. The antibacterial activity of nitrogen-implanted titania coatings has been monitored for Escherichia coli under visible light irradiation. Additionally ultraviolet/visible spectrophotometry tests have been carried out to measure the changes in the light absorbance of the doped films. Further characterization has been performed, including X-ray photoelectron spectroscopy, X-ray diffraction, and glow discharge optical emission spectrometry. As a result of nitrogen implantation, the light absorption peak shifted from ultraviolet region (UV-A) to visible wavelength range, which led to an increase of the antibacterial efficacy under visible light irradiation.