| Abstract |
In this work, the aims were to prepare nitrogen-doped TiO2 (N-TiO2) produced by hydrothermal route and to test the photocatalytic degradation of reactive red 141 (RR141) dye under UV and visible light irradiations in the effect of calcination temperature. The physical and chemical properties of synthesized N-TiO2 catalysts such as specific surface area, bandgap energy, crystallite size, phase structure and elements were characterized by using the Brunauer-Emmett-Teller (BET) technique, UV−Visible Diffuse Reflectance Spectroscopy (UV–Vis–DRs), Wide Angle X-ray Scattering (WAXS), X-ray Absorption Near Edge Structure (XANES) technique and X-ray Photoelectron Spectroscopy (XPS), respectively. The results presented that the effect of calcination temperatures was significant on specific surface area, the amount of elements and crystallite size, but insignificant on phase structure. The un-calcined N-TiO2 showed the highest specific surface area. The specific surface area was starting to decline when the calcination temperature was increased. The WAXS and XANES patterns revealed that the synthesized of all N-TiO2 samples only displayed the anatase crystalline phase. Moreover, the crystalline phase was not transfer to rutile phase at higher temperature (>600oC) comparing to previous researches [1, 2]. The bandgap energy of N-TiO2 was calculated by using the Kubelka–Munk theory to be about 2.90 eV, which appeared lower than other researches for anatase TiO2 phase (3.20 eV) [3]. Additionally, the XPS analyses of samples demonstrated that the N 1s peaks on N-TiO2 observed at binding energy 401 eV have been ascribed to chemisorbed molecular of nitrogen or interstitial nitrogen in TiO2 lattice [4, 5]. Also, the amount of nitrogen element diminished at high calcination temperature. Photodegradation of RR141 dye was performed under UV and visible light irradiation. The highest removal percentages were 98 and 51% for 3 h under UV and visible light illumination, respectively. In addition, the percent removal of RR141 was decreasing with higher calcination temperature of N-TiO2. |
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