Photocatalytic Degradation of Methylene Blue by Nanosized Visible Light Active Nitrogen and Iron Codoped Titania: Characterization and Feasibility Investigation

Abstract

Surface modification of titanium dioxide, TiO2, by codoping with nitrogen and iron to get the photocatalyst active under ordinary visible light was investigated for the photocatalytic degradation of methylene blue. The sol-gel method was used in preparing the modified titanium dioxide. Titanium tetraisopropoxide (TTIP), ammonium nitrate and ferric nitrate were used as precursors with the dopant concentration of 1% and calcination temperature at 600°C. The prepared photocatalyst samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) surface area, ultraviolet (UV)–visible diffusive reflectance spectra (DRS), and X-ray photoelectron spectroscopy (XPS) in order to study their physical properties. The results from XRD confirmed that all prepared photocatalyst were of the anatase phase whereby the codoping photocatalyst perfectly fitted with the standards and also found with high BET surface area. The analysis of band gap energy from UV-visible DRS was observed by a decrease through codoping nitrogen and iron into the TiO2 crystal structure. XPS analysis revealed that the nitrogen atom existed as interstitial N sites, whereas some Fe ions replaced Ti4+ ions due to their similarities in ionic radii. The efficiency of photocatalysts was tested by performing a standard batch photocatalytic degradation experiment under visible light. The result showed that 1.0% N, 1.0% Fe-codoped TiO2 photocatalyst yielded a maximum of 80.50% methylene blue degraded within 5 h of irradiation time.