纳米硅和纳米银复合颗粒对二氧化钛可见光光催化性能的影响

Influence of nano-silica-silver composite particle on TiO visible light photocatalytic activity

以TiO2为基体,通过水相共沉淀法掺入纳米硅、纳米银颗粒,制备了Si/TiO2和Ag@Si/TiO2复合催化剂。利用X射线衍射仪、扫描电子显微镜、紫外-可见分光光度计、电化学工作站、光致发光光谱仪对样品的晶体结构、微观形貌、光吸收性能、阻抗特性及电子空穴复合速率等进行表征,研究复合体系中Si掺杂量对可见光催化降解罗丹明(RhB)和亚甲基蓝(MB)染料的影响。结果表明:含Si的复合体系其可见光吸收光谱发生明显红移,且在长波长范围出现吸收峰。Si掺杂量为1%(质量分数)时,复合催化剂光吸收强度最强,催化效率最快。纳米银颗粒的引入进一步提高了Si/TiO2的可见光催化性能。可见光照射2.5h后,Ag@Si/TiO2对RhB的降解率比TiO2提高了14%;可见光照射3.5h后,Ag@Si/TiO2对RhB的降解率达到99%。在TiO2中掺入纳米硅和纳米银颗粒,银硅复合物Ag@Si一方面提供更多的光生电子-空穴对;另一方面充当电子受体,载流子迁移率得到提高,抑制了TiO2半导体光生电子与空穴的复合,从而提高了对RhB、MB的降解率。

Based on titanium dioxide(TiO2),Si/TiO2 and Ag@Si/TiO2 composites were prepared by incorporation of nano-silicon(Si)and silver(Ag)particles by aqueous phase coprecipitation method.X-ray diffraction(XRD),scanning electron microscopy(SEM),UV-Visible spectrum,electrochemical impedance spectroscopy(EIS)and photoluminescence spectroscopy(PL)etc.were used to characterize the crystal structure,morphology,optical properties,impedance characteristics and electron hole recombination rate of samples,to find out the effect of the doping amount of elemental composition of Si on the photocatalytic degradation of Rhodamine dye (RhB)and methylene blue(MB)by visible light.Results shown that the visible light absorption spectrum of the composite system containing Si was obviously red-shifted,and the absorption peak appeared in the long wavelength range.When the Si doping amount was 1wt%,the composite catalytic material had the strongest light absorption intensity and the fastest catalytic efficiency.Compared with pure TiO2particles,the photocatalytic performance of Ag@Si/TiO2 was obviously improved.Under the condition of visible light excitation and degradation for 3.5h,the degradation rate of RhB by Ag@Si/TiO2was 99%,and under 2.5hconditions,compared with TiO2,the degradation rate reached 14%.On the one hand incorporating Si and Ag into TiO2nanoparticles,Ag@Si provided more photogenerated electron-hole pairs.On the other hand,Ag acted as an electron acceptor,carrier mobility was improved,and TiO2 semiconductor photogenerated electrons and holes recombination were suppressed,enhanced the degradation efficiency of RhB and MB.