Photocatalytic and superhydrophilicity properties of N-doped TiO2 nanothin films

Pure TiO2 and nitrogen doped titanium dioxide (N-TiO2) thin films were prepared by sol–gel method through spin coating on soda lime glass substrates. TiCl4 and urea were used as Ti and N sources in the sol. XRD results showed nitrogen doping has retarded anatase to rutile phase transformation. The doping also leads to a decrease in roughness of the samples from 4 nm (TiO2) to 1 nm (N-TiO2). However, surface analysis by statistical methods reveals that both surfaces have self-affine structure. Optical band gap of thin films was shifted from 3.65 eV (TiO2) to 3.47 eV (N-TiO2). Hydrophilic conversion and photocatalytic degradation properties of thin films were investigated and exhibited that N-TiO2 thin film has more preferable hydrophilicity and photocatalytic properties under UV illumination.