低量La(上标 3+)掺杂S-TiO2光催化剂的制备、表征及其光催化活性

Abstract

La(superscript 3+)/S-TiO2 were prepared by sol-gel-impregnation method and characterized by means of XRD、BET、XPS and UV-Vis. Activities of prepared nano-photocatalysts were evaluated by decolorizing methyl orange solution as model compound to photocatalytic degradation. The mechanisms of effects of low amount La(superscript 3+)-doping on the photocatalytic activity of TiO2 nano-particles were discussed. The results show that S-doping can significantly enhance the photocatalytic activity of TiO2 nano-particles and La(superscript 3+)doped S-TiO2 can further enhance the photocatalytic activity of TiO2 nanoparticles. Under optimal addition amount of La(superscript 3+) into TiO2 0.369% (mass fraction), decolorizing rate of methyl orange on La(superscript 3+)/S-TiO2 nano-photocatalyst was 92.4% after 120 min irradiation. The analytical results of XRD show that the presence of low amount of La(superscript 3+) in TiO2 can inhibit the phase transformation from anatase to rutile, suppress the growth of TiO2 grains and raise the specific surface area. The analytical results of XPS indicate that S、La(superscript 3+) doping can result in the increase in the density of the surface hydroxyl, and cationic S(superscript 6+) is incorporated into TiO2 lattice and substitutes a part of Ti(superscript 4+) The analytical results of UV-Vis indicate that the La(superscript 3+)/S-TiO2 catalyst has stronger absorption in the ultraviolet region than the pure TiO2. Compared with pure TiO2, the enhanced photocatalytic activity of the La(superscript 3+) doped TiO2 nano-powders can be due to the increase of the density of the surface hydroxyl and the specific surface area, and the improvement of the ultraviolet light absorption properties of the particle surface.