Research Of Titanium Dioxide Catalyst Prepared At Low Temperature

Carbon doped TiO2(C-TiO2) nanoparticles were prepared by sol-gel method without using external carbon precursors and calcinating at a lower temperature. Factors affecting photocatalytic activities of C-TiO2 nanoparticles such as water amount, ethanol amount, acetic acid amount, calcinating temperature, calcinating time were studied by the degradation of methyl orange aqueous solutions under visible light. TiO2 nanoparticles showed optimal photcatalytic activities when the molecule ratio of TNB and distilled water was 1:7 and the volume ratio of TNB, ethanol, acetic acid was 10?13?4, calcinating temperature and time were 270℃and 0.5 hours, respectively.C-TiO2 nanocomposites were characterized by means of transmission electron microscopy (TEM), X-ray diffractiometer (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectrocopy (FTIR), N2 isothermal adsorption-desorption, UV-vis-diffuse reflectance spectroscope (DRS) and Raman spectra. Results showed C-TiO2 had primarily the anatase phase and mesoporous structure; the specific surface area was about 251.38 m2.g-1; there were two existing forms for carbon atom in TiO2, e.g. doping carbon which replaced Ti atom in the lattice of TiO2 and organic carbon which remained in TiO2 with the form of organic group. The carbon atoms from the titanium alkoxide precursor can incorporate into the lattice of TiO2 and become the doping carbon by well controlling the calcination temperatures. The banding energy of TiO2 was reduced from 3.2 eVto 2.79 eV by the doped carbon. C-TiO2 nanocomposites had higher absorption in the visible region compared to P25.The photocatalytic activities of C-TiO2 nanocomposites under visible light and UV light irradiation were investigated by evaluating the photodegradation of methyl orange and rhodamine B as the model pullutants. The results showed that the photocatalytic activities of C-TiO2 nanocomposites were superior to those of the commercial TiO2 nanoparticles(P25).The recyling experiments of photocatalytic degration of methyl orange under visble light irradiation and the photocatalytic activites of C-TiO2 nanocomposites irradiated under visible light for a long time showed that the photocatalytic activites of C-TiO2 nanocomposites were excellent.The kinetic order of the photocatalytic degradation reactions of methyl orange photocatalyzed by C-TiO2 nanocomposites was 0.7. The holes were the main active species in the experiment of methyl orange photocatalytic degration. The reasons that the photocatalytic activities of C-TiO2 nanocomposites were improved were discussed, and it could be thought that the doping carbon in the lattice of TiO2 and larger specific surface area of C-TiO2 nanocomposites might the main reasons for resulting in higher photocatalytic activities of C-TiO2 nanocomposites.