Hydrophilic, antibacterial and photocatalytic properties of TiO 2 composite films modified by the methods of N + ion implantation and doping of CNTs under visible light irradiation

The carbon nanotubes (CNTs) doped TiO2 films were synthesized using the sol-gel method. To obtain better visible light induced properties, the CNTs-TiO2 composite films were implanted by nitrogen ions (N+ ions) with ions energy of 40 keV and doses of 5 × 1015, 1 × 1016, 5 × 1016, and 1 × 1017 ions/cm2 using an implanter equipped with Freeman ion source. SEM, XRD, XPS and UV–Vis spectra were utilized to explore the surface morphology, crystal structure, chemical composition and optical characteristics of the composite films respectively. The visible light induced properties of the composite films were examined by the experiments of degradation of methylene orange, water contact angle measurements and sterilization of E. coli. The XPS results showed the replacement of oxygen by implanted N+ ions in TiO2 lattice. The UV–Vis spectra exhibited the red-shift for all implanted samples. Meanwhile, the results of visible light induced experiments showed that the photocatalytic degradation efficiency and antibacterial activity of TiO2 composite films were enhanced, and the water contact angle decreased, which indicates that those properties of TiO2 composite films were improved. The best performance of hydrophilic, photocatalytic and antibacterial properties of the composite TiO2 films was corresponding to the implanted dose of 1 × 1016, 5 × 1016 and 1 × 1017 ions/cm2 respectively.