Preparation Of M_xO_y/SiO₂ Nanocomposites By Co-sol Double Hydrolysis Method

Nanocomposites can not only maintain the advantages of the material properties of each component,but also have good comprehensive properties that are not possessed by a single component material,thus becoming a hot topic of current research.SiO₂-based nanocomposites have been widely studied in recent years due to their advantages of non-toxicity,easy availability of raw materials and controllable structure.In these materials,metal oxide(M_xO_y)/SiO₂nanocomposites are mostly prepared by the two-step method.However,there are some difficulties and challenges in these preparation methods,such as the difficulty in controlling the dispersion of M_xO_ynanomaterials and the low yield.In order to solve the above problems,a new method,co-sol double hydrolysis method,was proposed to synthesize M_xO_y/SiO₂nanocomposites in one step.On the basis of regulating the preparation of SiO₂matrix pellets,the NiO/SiO₂nanocomposite was prepared by a new method and its structure was tested and analyzed.The mechanism of this synthesis method was discussed.Finally,the universality of the new synthesis method is verified by using Ag₂O and Zn O.The main research results are as follows:1)By studying the influence of the droplet amount of ethyl orthosilicate on the diameter of SiO₂matrix nanometer ball during the reaction process,the regulation and preparation of SiO₂matrix nanometer ball diameter between 50 nm and 230 nm were successfully realized;2)NiO/SiO₂nanocomposite was successfully prepared by using the method of co-sol double hydrolysis with NiO as the composite object.The results showed that the polycrystalline NiO nanoparticles with a diameter of about 20 nm were dispersed on the surface of amorphous SiO₂matrix pellets with a diameter of about 200 nm;3)Compared with pure NiO prepared by alkaline hydrolysis method,the composite of NiO nanoparticles on the SiO₂matrix was significantly improved and the agglomeration effect was reduced;4)Compared with the two-step synthesis method,the formation of Ni(OH)₂and SiO₂matrix in the co-sol double-hydrolysis method is a competitive process,and there is a space blocking effect,which reduces the particle size of NiO and SiO₂matrix in the composite products;5)Based on the analysis of the formation reasons of the microstructure of NiO/SiO₂nanocomposites,the synthesis mechanism of the co-sol double hydrolysis method was proposed,and the general applicability of this method was verified through Zn O and Ag₂O,and the Zn O/SiO₂and Ag₂O/SiO₂nanocomposites were successfully prepared.