Study On Photocatalytic Activity Of Cobalt And Metal Co - Doped TiO 2

Metal and nonmetal doping modification of TiO₂, is an effective method to improve the quantum efficiency, catalytic activity and expand the range of visible-light and improve the separation efficiency of photogenerated electron-hole. This paper adopted the sol-gel synchronous synthesis method to prepared Ag/N-C-S/TiO₂, Ce/N-C-S/TiO₂ and Fe/N-C-S/TiO₂ four elements doping TiO₂ photocatalyst, and studied photocatalytic mechanism and doping mechanism of doped modification TiO₂ catalyst degradating methyl orange in visible light.The prepared samples were characterized by X-ray photoelectron spectroscopy（XPS）, Fourier transformation infrared spectroscopy（FT-IR）, scanning electron microscopy（SEM）,transmission electron microscopy（TEM）, Thermogravimetric analysis-Differential thermal analysis（TG-DTA）, X-ray diffraction（XRD）, specific surfacte area analyses（BET）, Raman and UV-visible diffuse reflectance spectroscopy（UV-vis DRS）. Photoluminescence（PL）.It was showed that four elements co-doping not only can decrease TiO₂ crystalline size, increase TiO₂ specific surface area and anatase content of TiO₂, but also improve the separation efficiency of photo-generated electrons-hole. N element in cysteine forming O-Ti-N in forbidden band, C and S elements replacing Ti4+ in the lattice and forming CO32-and SO42- structure in band gap, generated impurity level in forbidden band, reduced excitation energy, increased the hydroxyl content, and improved the TiO₂ visible light catalytic ability. The defined amountprecious metals Ag, rare earth metal Ce and transition metal Fe, which existed on the surface or in the lattice, captured photo-generated electrons efficiently and produced the active substances such as ·O2-and ·OH indirectly, and contributed to improving TiO₂ photocatalytic activity.The modified TiO₂ with 4mol%cysteine content, when Ag, Ce and Fe doping content was 0.75mol%, 1mol% and 2mol%, respectively, and calcination temperature was350, 350 and 400 ℃, respectively, the co-dopingcatalyst Ag/N-C-S/TiO₂, Ce/N-C-S/TiO₂, Fe/N-C-S/TiO₂ was exhibited the best photocatalytic performance for the degradation of MO.Under 500 WXenon lamp simulated solar radiation for 120 min, the degradation rateof MO could achieve 87.6%, 87.6% and 87.6%, respectively.