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.