Photocatalytic Decolorization of Methylene Blue by N-doped TiO2 Nanoparticles Prepared Under Different Synthesis Parameters

Although several studies concerning the preparation of nitrogen doped titanium dioxide visible-light active photocatalyst have already been reported, the effects of dopant concentration and calcination temperature have been rarely investigated. This paper focuses on the preparation of nitrogen doped titanium dioxide (N-doped TiO2) under different calcination temperature and nitrogen dopant concentration synthesizes by sol-gel method. The physicochemical characteristics of the prepared samples were examined using X-ray photoelectron spectroscopy (XPS), X-ray diffractometer (XRD), Brunauer Emmett Teller (BET) analyzer, and UV-Vis spectrometer. Methylene blue was used in this study as a test chemical. The results demonstrated that the sample prepared under calcination temperature of 600 °C show 8.33 and 5.57 % of rutile TiO phase depends on the dopant concentration. Furthermore, the sample prepared at a lower calcination temperature of 400 °C and nitrogen to titanium (N/Ti) molar ratio of 2 and 6 exhibited larger specific surface area of 80.18 and 77.07 m^2g^-1, respectively. The photoactivity of the catalyst was also investigated on methylene blue decolorization using the different N-doped TiO2 sample. The experiments demonstrated that the sample prepared at higher N/Ti molar ratio (6) and lower calcination temperature (400 °C) demonstrates about 80 % efficiency under visible light. It was concluded that the higher photoactivity of the N-doped sample prepared at higher dopant concentration and lower calcination temperature is due to synergistic effects of higher surface area, smaller crystal size and higher nitrogen content in the crystal lattice of TiO2.