The Photo-induced Characters Of The Nanoscale Titanium Dioxide Thin Films Prepared By Sol-Gel Method

While the annoseale photocatalyfie activity and the photo— induced properties of titanium dioxide thin films were characterized,the effect of transitinnal metal Sb doped into titanium dioxide thin films upon the microstructuse,photo-indeced charaetars,electrochemical pmpertias and the stabilization in acid or alkaline environment were studied in this paper.The preparation of the thin films includes two parts One is the preparation of Si02一Ti02 composite thin films at room temperature in air.Another is the deposition of Sb doped nanoscalc Ti02 thin films 1.In the section of photocatalytic Ti02 thin films were prepared at room temperature in air,Ethyl delicate((C2Hs)4Si04)and TiCl4 were used as the precursor 0f Si02 and Ti02 respectively.The Nanoscale silicon dioxide and titanium dioxide composite(si02-Tio2)thin films wem uniform and transparent with the thickness of about 100nm were prepared. Thc chemieal states of the elements on the surface or near the surface were measured by XPS.The msults indieated that the Ti on/nearthe surface of the thin films existed not only as Ti4+ but also aS Ti3+.After ultraviolet(UV)irradiation for some time,the spectra of Ti2p3/2 changed obviously.Fitted results showed that the spectra of Ti3+ risen drastically after UV irradiation for long time(about 24h) accompaniedbyan up-forward tendency in the intensity of Ols spectra corresponded to Ti3+. These illustrated that part of the Ti4+was changed to Ti3+ after UV irradiation The crystalline stnlctore ofthe Si02-Ti02 thin films were characterized by X-ray diffraction(XRD).The crystalline structure of the Ti02 in the Si02-Ti02 thin films was in a majority of anatase state with the crystallite size of 14— 20nm.The AFM was used to study the morphology of the thin films annealed at different temperature and it effected onthe crystalline size of titanium dioxide For Si02 effect,the surfaces of the samples treated at below 200。C were lumpish strucure with grain size of 0.2pm. ARer treated at 450℃ for 1 hour,the grain size reduced to 50-100mn. The samples prepared at room temperature had excellent photo-induced superhydrophilicity and superior photocatalysis.After ander UV irradiation for 40min, the contact angles for all samples were drastically reduced to 0。and it also was between 1.5。t0 3。after storage in dark for 24 hour.There was few or none effcct on photocatalysis of the thin films heat treated below 200。C,the staircase reaction speed constant(k) of?0.0220 h-1·cml-2 and 0.0233 h-1.cm-2.respectively.But the photocatalysis of thin films treated at or over 450℃ for l hour was reduced obviously,which staircasereaction speed constant(k)was about 0.0108h-1.cm-2 and 0.0097 h-1.cm-2. The adherence between the thin films treated at different temperature and substrate was characterized byboiling water trtatment The samplestreated below 200℃showed superior photo-induced supethydrophilicity after treated in boiling water for 20min.The contact angle was less than 1。under UV(k=254nm, P=200pW/cm2)irradiated for 40min.It illuminated that the thin films had strength adherence and stabilization The Ti02:Sb thin films with thc transparent larger than 80%were prepared by dip-coating sol-gel method.After doping proper amount of Sb,a part of Ti4+ in Tio2 were replaced by Sb3+ and Sb combined with the O in Ti02 to form the structure of Sb-O-Ti,the crystal lattice parameters a and c were changed,and the crystalline rate of the Tio2 in the thin films is enhanced so that the content of anatasc Ti02:Sb were increased.When the concentration of dopant Sb was excessive.Sb interacted wim itself to form Sb-Sb structure,ruining the original anatase structure.So the optimization content of Sb is aboutO.2%. The photoelectric conversion character of TiO2 thin films are improved after Sb doping in it.When the content of Sb reached 0.2‰the photocurrent density was. about 42.49uA·cm-2 that was 11 times to the non-doped Ti02 thin films subjecting...