Synthesis Of Unique SnO₂/ZnO Core-shell Nanorods And Nanoflowers And Their Field Emission Properties

The nanocomposite with core/shell structures is an ordered assembly system in which one nanomaterial is covered by another nanomaterial via chemical bond or other interactions. These structures present many new functions and particular optical, electric, magnetic, or catalytic properties which could no t been obtained from single nanoparticles. In this paper, the research advance, properties and synthesis methods of the core/shell nanostructures are reviewed.In this paper, the zinc acetate(Zn(CH3COO)2·2H2O) is used as the starting materials and we take C6H12N4or C6H15NO3as the catalyst,respectively. Then according to equal molar ratio,it is Preparation of the solution with different concentration.ZnO nanoparticles grow on the surface of SnO2nanorods and SnO2nanoflowers by hydrothermal method. It is exploration of the synthesis method of SnO2/ZnO core-shell nanorods and nanoflowers and field emission properties.In the silicon substrate, we take SnO2nanorods and nanoflowers powder to do experiments to get different composite products by changing the concentration of Zn(CH3COO)2·2H2O and using different catalysts.The results show that if you want to get the better coated nanoparticles, we can take the process:First we put the prepared SnO2nanorods power into the beaker under an ultrasonic stirring for2h.Making the solution concentrations of Zn (CH3C00)2.2H20and C6H12N4are0.005mol/l and the pH of solution adjusts to7.5.After that SnO2nanorods and the preparation of solution with Zn (CH3C00)2.2H20and C6H12N4are added into the autoclave.The reaction temperature constant for85℃and reaction time for7hours. After the reaction, we can get better effect of coated nanoparticles.In the experiment, we find that the reaction temperature, time and catalyst have an large influence on the morphology of ZnO nanoparticles, as follows:(1)In the same case of the temperature, time and pH, we find that use different catalysts, SnO2nanorods will grow different shapes of the ZnO particles.(2)under the same conditions of pH and catalyst, reaction temperature and time have a great influence on the shape of the zinc oxide. If reaction time is too long or reaction temperature is too high may lead to the formation volume of the ZnO particles is too big, not coating.Field emission (FE) showed that the as-synthesized SnO2/ZnO core-shell nanoparticles have a lower turn-on field of3.2V/μm.The research shows the core-shell structure of the products can effectively improve the field emission properties including a lower starting voltage, good electric conductivity.The material has the potential to be one kind of raw materials of field emission devices.