In this study, preparation of Nb-doped (0–20 mol% Nb) TiO2 dip-coated thin films on glazed porcelain substrates via sol–gel process has been investigated. The effects of Nb on the structural, optical, and photocatalytic properties of applied thin films have been studied by X-ray diffraction, Raman spectroscopy, and scanning electron microscopy. Surface topography and surface chemical state of thin films was examined by atomic force microscope and X-ray photoelectron spectroscopy. XRD and Raman study showed that the Nb doping inhibited the grain growth. The photo-catalytic activity of the film was tested on degradation of methylene blue. Best photo-catalytic activity of Nb-doped TiO2 thin films were measured in the TiO2–1 mol% Nb sample. The average optical transmittance of about 47% in the visible range and the band gap of films became wider with increasing Nb doping concentration. The Nb5+ dopant presented substitutional Ti4+ into TiO2 lattice.
