Preparation And Research Of Metal-Semiconduction Hollow Sphere Nanocomposites

The application of nanomaterials in the field of catalysis is becoming more and more concerned by researchers.In the catalytic research of many metals and their oxide nanomaterials,Ti02 and Au nanoparticles have been extensively studied due to their unique advantages.However,there are some shortcomings in the use of these two catalysts.For example,the small surface area of Ti02,crystal phase transformation,crystal growth,low quantum efficiency,only in response to ultraviolet light;Au nanoparticles have a high surface energy and is easy to agglomerate,so that particle size and shape changes on the process of catalysts,which affect their catalytic performance.For this reason,the improvement of the catalyst is more and more attention.On this basis,this paper has done the following work:(1)A series of CuxO-TiO2 hollow nanospherical composites with different mass percents(0.25%?0.50%?1.0%)of copper element were prepared by impregnation method,and the Ti02 hollow nanosphere was prepared by hydrolysis of tetraethoxy titanium on the surface of spherical Si02 nanoparticles and corrosion of Si02 in NaOH solution.CuxO-TiO2 hollow nanosphere displayed higher photocatalytic activities towards acetaldehyde degradation to CO2 than TiO2@SiO2 nanosphere and TiO2 hollow nanosphere under UV and visible-light irradiations due to the narrowed band gap of Ti02 and enhanced charge separation after copper element introduced.Specially,the CuxO-TiO2 hollow nanosphere shows high catalytic activities in the degradation under visible-light irradiation.Due to the larger surface area and more exposed catalytic active sites,when the content of copper is 0.50%,the catalytic efficiency of the composite materials is to achieve the best effect,which provides the possibility on application of the catalyst in daily life.(2)Si02 microspheres with different diameters were prepared in Stober method,and the Si02 microspheres were uniformly coated with Zr02 by adsorption and hydrolysis of ZrOCl2.The Zr02 hollow microspheres were then obtained after SiO2 was removed by NaOH solution,and Au@Zr02 hollow microspheres were finally prepared by deposition-precipitation method.Catalytic properties of Au@Zr02 hollow microspheres in reduction of paranitroaniline were studied carefully.The research results indicate that the SiO2 microspheres have regular shape and good dispersity.The sizes and the surface areas of the Zr02 hollow microspheres could be controlled effectively by the diameters of SiO2 microspheres.Compared to the solid microsphere Au@Zr02,the Au@Zr02 hollow microspheres showed good catalytic performance in reduction of p-nitroaniline,and p-nitroaniline was completely reduced to p-phenylenediamine in 7 minutes at 45?.