Synthesis Of Modified Titanium Dioxide Photocatalyst

The excellent performance of semiconducting oxide materials in photocatalytic oxidationrealm attracts a large number of scholars in-depth study. TiO2has been widely considered asthe most promising photocatalyst due to its high photocatalytic activity, good chemical andbiological stability, non-toxicity, and low cost, etc. However, because of its large energy bandgap of3.2eV, TiO2could only be excited under UV irradiation, which accounts for onlyabout5%of solar energy. In recent years, great interests have been focused on thedevelopment of photocatalysts with visible light response. Doping TiO2with metal, nonmetalion,coupling TiO2with different semiconductor and co-doped have been regarded as theeffective method of modifying TiO2. The single method of doping or coupling with TiO2affects a little. Therefore this paper will modify TiO2through the method of co-doped withmetal ion.In this paper, the W/TiO2was prepared by sol-gel method and was characterized byX-ray diffraction (XRD), UV-visible diffuse reflectance spectroscopy (UV-Vis DRS),transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS),Fluorescent (FL), Energydispersive X-ray spectroscopy (EDS), and specific surface area (SSA).Methyl orange (MO) was chosen to test the photocatalytic ability of W/TiO2using the xenonlamp as the simulated sunlight. Several factors, such as doping amount of W, calcinationtemperature, and calcination time in the preparation process, pH of solution and initialconcentration of solution were evaluated. Meanwhile, the kinetics of MO removal wasinvestigated. The results showed that, the optimum conditions were as follows: the W-Timolar ratio was0.8%, the calcination temperature was400C, the calcination time was3h, thepH of the solution was3.0and the initial concentration of MO was20mg/L. Under thecondition of the optimum preparation conditions and reaction, the degradation of MO underthe UV light irradiation reaches91.1%, and it is45.4%under the simulated sunlightirradiation.The stability of W/TiO2was tested by repeating the same experiment for fourtimes and there was no significant decrease of photocatalytic activity of the catalyst found in the result.the degradation of MO under the UV light irradiation above85.0%, and it overtop40.0%under the simulated sunlight irradiation.The La/W/TiO2photocatalyst prepared at optimized preparation condition was dopedwith La by the same method, thus the La/W/TiO2photocatalyst was prepared. The sampleswere characterized by XRD, UV-Vis, TEM, XPS, FL, EDS and SSA. The results showed that,the best amount of La is4wt%in the La/W/TiO2system, the calcination temperature was400C, the calcination time was3h, the pH of the solution was3.0and the initialconcentration of MO was20mg/L.Under the condition of the optimum preparation conditionsand reaction, the degradation of MO under the UV light irradiation reaches97.2%, and it is67.3%under the simulated sunlight irradiation.The stability of La/W/TiO2was tested byrepeating the same experiment for five times and there was no significant decrease ofphotocatalytic activity of the catalyst found in the result.the degradation of MO under thesimulated sunlight irradiation is higher than60.0%.