Photodegradation of phenol by N-Doped TiO2 anatase/rutile nanorods assembled microsphere under UV and visible light irradiation

N-doped TiO2 anatase/rutile nanorods assembled microspheres were successfully synthesized via a simple and direct sol-gel method containing titanium-n-butoxide Ti(OBu)4 as a precursor material, nitric acid as a catalyst, and isopropanol as a solvent. By manipulating calcination temperature, the photocatalyst consisting of different phase compositions of anatase and rutile was obtained. The prepared TiO2 nanoparticles were characterized by means of x-ray diffraction (XRD), field emission scanning microscope (FESEM), atomic force microscopy (AFM), Brunauer-Emmett-Teller (BET) analysis, UV-Vis-NIR spectroscopy, and fourier transform infrared (FTIR). The results from UV-Vis-NIR spectroscopy and FTIR revealed the direct incorporation of nitrogen in TiO2 lattice since visible absorption capability was observed at 400-600 nm. XPS study indicated the incorporation of nitrogen as dopant in TiO2 at binding energies of 396.8, 397.5, 398.7, 399.8, and 401 eV. Calcination temperature was observed to have a great influence on the photocatalytic activity of the TiO2 nanorods. The photocatalytic activity of the prepared mixed phase of anatase/rutile TiO2 nanoparticles was measured by photodegradation phenol in an aqueous solution under UV and visible irradiations. N-doped TiO2 anatase/rutile nanorods assembled microsphere (consists of 38.3% anatase and 61.7% rutile) that was prepared at 400 °C exhibited the highest photocatalytic activity after irradiated under visible and UV light for 540 min. The high performance of photocatalyst materials could be obtained by adopting a judicious combination of anatase/rutile prepared at optimum calcination conditions.