SiO_2负载Ag-TiO_2光降解催化剂的制备及性能研究

Study on the photodegragradation properties and preparation of silica supported Ag-TiO_2

以钛酸丁酯为钛源、正硅酸乙酯为硅源、硝酸银为Ag源,采用溶胶-凝胶法制备Ag掺杂TiO_2负载型催化剂x%Ag-TiO_2/SiO_2（x=0.5~3.0）.通过X射线衍射（XRD）、场发射扫描电镜（FE-SEM）、透射电子显微镜（TEM）、傅里叶红外光谱仪（FT-IR）、X射线光电子能谱（XPS）、紫外-可见-近红外光谱等对样品进行了表征.以罗丹明B（Rh B）为模拟污染物,在可见光照射下研究了Ag掺杂量对催化剂光催化性能的影响.研究结果表明,适量Ag的掺杂能在Ag-TiO_2界面处形成肖特基势垒,起到捕获电子的作用,使得在TiO_2中形成的电子空穴对有效的分离,从而提高催化剂的光催化能力.SiO_2的引入有利于TiO_2纳米颗粒更好的分散,有效的抑制了颗粒之间的团聚,从而增强了光催化剂的吸附能力.而且当SiO_2与TiO_2的质量比为1∶10一定时,Ag掺杂量为1.0%时,催化性能达到最佳,此时以Rh B为模拟污染物进行降解,经过105min可见光照射,降解率达到99.5%.

Silica supported silver doped titanium dioxide particles were synthesized by sol-gel method using titanium tetra isopropoxide as the titanium source.Ag doping TiO_2 using AgNO_3as the Ag source.The structure and physical properties of Ag-TiO_2/SiO_2 particles are characterized by field-emission scanning electron microscopy（FE-SEM）,fourier transform infrared spectroscopy（FT-IR）,X-ray diffraction（XRD）,transmission electron microscopy（TEM）,X-ray photoelectron spectra（XPS）,cary series UV-Vis-NIR Spectrophotometer.Photocatalytic properties of the different amount of the Ag doped has been investigated for the degradation of rhodamine B（Rh B）.The result show when the quality of titanium and silicon was constant,Ag doping significantly enhanced the photodegradation activity under visible light irradiation result from the schottky barrier formed at the Ag-TiO_2 interface,which serve as the electron trap,facilitating the separation of electrons and holes.Compared with TiO_2,introduction of SiO_2 effectively inhibit the aggregation of particles thus enhance the adsorption capacity of the photocatalyst.And the best catalytic performance obtained through the mass ratio of silicon and titanium was 10%,and the doping mass of Ag is 1.0%.After 105 min visible light irradiation,the degradation rate of Rh b reached 99.5%.