Effects of Heat Treatment and Atmosphere on the Visible Light Photocatalytic Activity of Nano-TiO_2

The nano-TiO_2 powders were characterized by X-ray diffraction (XRD),transmission electron microscope (TEM),diffuse reflectance spectra (DRS) and X-ray photoelectron spectroscope (XPS).The results show that nano-TiO_2 is transformed to rutile crystal after treating at 400℃in N_2 atmosphere and the nano-TiO_2 particles obtained are uniform.Part N atoms are intruded into the TiO_2 crystals and substituted for some of O atoms,which produce oxygen defects.Those oxygen defects become the center of photo activity,which result in the increase of absorbed photons and the formation of broad band gap and make the absorption spectrum move to the visible light.The photocatalytic degradation of methylene blue shows that the visible light catalytic activity of nano-TiO_2 calcined in N_2 atmosphere is improved.