Enhanced superhydrophilicity of N+ implanted multiwalled carbon nanotubes-TiO2 composite thin films

Multiwalled carbon nanotubes-TiO2 (MWCNTs–TiO2) composite thin films were deposited on glass substrates by the sol–gel spin coating technique and doped with nitrogen ions using ion-implantation. The dose of implanted N+ was chosen as 3 × 1015 and 1 × 1016 ions/cm2, respectively. Scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) were used to study the structural and chemical properties of the films. UV–Vis spectrophotometer was used to evaluate the absorbance spectra of the films. The water contact angle (WCA) of thin films under UV/Vis light irradiation after storage in a dark place was measured by a contact angle analyzer. The results showed that the absorption edge of N+ implanted MWCNTs–TiO2 films shifted to longer wavelength, and some of the lattice oxygen atoms were substituted by N+. Both doped MWCNTs and nitrogen ions enhanced the superhydrophilicity of TiO2 films under UV light irradiation. However, visible light induced hydrophilicity was only appeared on N+ implanted MWCNTs–TiO2 films.