Research On The Synthesis Of Carbon-coated Cu Nanoparticles By Gaseous Detonation Method

Metal nanoparticles have attracted the attention of researchers because of their excellent properties.However,it is easy to be oxidized in the air due to its large surface area,which limits its development to a great extent.The carbon coating technology not only protects the metal nanoparticles from oxidation by the outside world,but also broadens its application in biology.In this paper,Copper acetylacetonate was used as reactant,hydrogen and oxygen,hydrogen and air,methane and oxygen,benzene and oxygen were used as explosive source respectively.Carbon coated copper nanoparticles were first synthesized by gas explosion method.In order to analyze the feasibility of the synthesis of carbon encapsulated metal nano copper materials by gas explosion,the proportion of the reaction gas is determined by the gas explosion limit and the negative oxygen balance condition,and theoretical values of detonation pressure,detonation velocity,detonation temperature and density are conducted through the CJ classical detonation theory and first law of thermodynamics.On the basis of these parameters,the synthesis mechanism of carbon encapsulated metal nanoparticles was analyzed.An experiment is conducted using hydrogen and oxygen as the explosion source and changing the precursor mass,which successfully synthesizes carbon-encapsulated copper nanoparticles with diameter of 20-50 nm.The results of XRD,Raman and TEM analysis showed that the particle size,the degree of graphitization and the coating effect were improved with the increase of the quality of acetylacetone copper.However,with the increase of the mass of the reactants,because the volume of the reaction vessel is constant,the density of the reaction gas increases,so the agglomeration of the products is serious.In order to solve the problem of copper oxide impurity in the experiment,the experiment was carried out by changing the ratio of hydrogen and oxygen under the condition of keeping the quality of acetylacetone copper unchanged.The results show that with the change of the ratio of hydrogen and oxygen,the type of copper oxide in the products are also changed,and the copper oxide will not be produced at a certain proportion.The effects of different kinds of gases on the synthesis of carbon encapsulated metal nanoparticles were investigated by using different explosive gases.The results show that the carbon coated structure can be synthesized by using hydrogen and oxygen as the main blasting source,while the other two kinds of gases can't produce this kind of structure.Based on the calculation results of the detonation parameters of four kinds of gases,it is found that the detonation temperature and detonation pressure are the decisive factors for the success of the experiment.Finally,the oxidation resistance of carbon coated copper nanoparticles was analyzed,and the products were analyzed by TEM.In the comparison of the TG-DSC curves with pure copper powder,it was found that the carbon coated structure inhibits the oxidation of copper nanoparticles to some degree.