Synthesis And Properties Of Multielement Photocatalytic Materials Based On Titanium

A great deal of attention has been devoted to nano-sized TiO₂ for its excellent performance such as chemically stable,non-polluting,high surface area and high photocatalytic activity.However,its practical application is limited due to its wide band gap（3.2 eV）,low-light quantum efficiency,the optical response narrow,easy aggregation and hard separation and recovery of the photocatalyst.For the above problems,single-doping and co-doping and support were used in the experiment to modify TiO₂ to enhance the photocatalytic efficiency of TiO₂ reuse and recycling.The composite photocatalyst characteristics were investigated by X–ray diffraction（XRD）,scanning electron microscope（SEM）,FT-IR,X-ray photoelectron spectroscopy（XPS）、UV-vis DRS and N₂ adsorption-desorption,While methyl orange degradation effects of different preparation conditions on the photocatalytic activity.The main work is composed of three parts:Doped TiO₂ composite photocatalyst was prepared by sol-gel method.The results indicate that all the samples presented anatase TiO₂ phase,Gd³⁺and In³⁺ into the TiO₂ crystal lattice by substituting Ti⁴⁺,the lattice distortion,swelling,leading to lattice cell expansion.Doping inhabited growth of TiO₂ crystal,increasing the special surface area of the Ti O₂,the average pore size decreased,while the special surface area increased,the largest special surface area was 122.7 m2/g for the 3%In-0.1%Gd-TiO₂ sample.Meanwhile,Gd and In co-doping narrows the band gap of TiO₂.With increasing calcination temperature,TiO₂ crystalline increased gradually,the special surface area decreased.The highest photocatalytic activity was 63% for the 3%In-0.1%Gd-TiO₂ sample calcinated at 400 ℃.After 60 min of UV-light irradiation,methyl orange degradation rate was 90% for the 3%In-0.1%Gd-TiO₂ sample,while methyl orange degradation rate was 70% with 0.1%Gd-TiO₂.In this study,the optimum amount of catalyst to 200mg/L.x%In-0.05%Sm-TiO₂ composite photocatalyst was prepared by sol-gel method.The results show that all the samples presented anatase TiO₂ phase at different In doping and calcination temperature,co-doping on TiO₂ inhabited grain growth and decreased the crystallite size,TiO₂ absorbing boundary red shift and the number of hydroxyl groups on a Titanium dioxide surface increased.Thus the special surface area increased,the largest special surface area was 113.1 m²/g for the 5%In-0.05%Sm-TiO₂ sample.With increasing calcination temperature,TiO₂ crystalline increased and the special surface area decreased gradually.The highest photocatalytic activity was 69.8% for the 5%In-0.05%Sm-TiO₂ sample calcinated at 400 ℃.After 60 min of UV-light irradiation,methyl orange degradation rate was 97.7% for the 5%In-0.05%Sm-TiO₂ sample,methyl orange was almost compeletly discolored。Using tetrabutyl orthotitanate（TBOT）as Ti source,HZSM-5 zeolite as the support,In-TiO₂（x%）/HZSM-5 composites was prepared by sol-gel method.The results show that the suppoted TiO₂ maintaines anatase phase,doping inhabited growth of TiO₂ crystal and decreased the crystallite size.With TiO₂ loading increase,the special surface area decreased gradually,the largest special surface area was 253.3 m2/g for the In-TiO₂（20%）/HZSM-5 sample.The highest photocatalytic activity was 60% for the In-TiO₂（50%）/HZSM-5.Using same method prepared 3%In-0.1%Gd-TiO₂（x%）/HZSM-5 and 5%In-0.05%Sm-TiO₂（x%）/HZSM-5 composite photocatalyst.Compared with the 3%In-0.1%Gd-TiO₂,5%In-0.05%Sm-TiO₂,photocatalytic activity reducing after the load.