Microwave Solvothermal Synthesis And Mechanism Of Cu₂Se/rGO Nano Powder

As the environmental pollution and energy crisis become more and more serious,the practical significance of research on thermoelectric materials has been strengthened,which has attracted more and more attention from countries and scholars.The development of theory and advanced synthesis methods have caused the performance of traditional thermoelectric materials to be greatly improved.Because Cu₂Se itself has a liquid-like effect and has good thermoelectric properties,it has caused further research on Cu₂ Se.The methods to improve the thermoelectric performance of Cu₂ Se are mainly nano-crystallization,doping,compound engineering,deviation from stoichiometric ratio,etc.,aiming to further reduce the thermal conductivity,increase the conductivity,and increase the z T value.Because microwave heating technology directly converts microwave energy into heat energy,it has the characteristics of volume heating,uniform heating,selective heating and instantaneous heating that traditional heating methods do not have.In this paper,microwave efficient heating technology is used to synthesize Cu2 Se composite materials.Under microwave solvothermal synthesis conditions,process parameters are adjusted,including reaction temperature,holding time,raw material ratio and addition of surfactant to prepare high purity,uniform size Cu2 Se powder.The influence of various factors on the phase structure,size and morphology of Cu2 Se powder is analyzed to provide better process parameters for the subsequent composite graphene.The specific research content and results are as follows:During microwave heating and conventional heating,molecular dynamics simulation was used to study the hydrogen bonding network structure of the reaction solvent ethylene glycol and the diffusion coefficient of the reactants.The presence of a microwave electric field can change the hydrogen bond structure,reduce the number and life of hydrogen bonds,weaken the hydrogen bond network,and the diffusion coefficients of the reactants are greatly improved.The introduction of microwave enhances the mass transfer process of the system and accelerates the reaction and nucleation rate.Cu₂Se powder was prepared by microwave solvothermal method.After XRD and SEM analysis,the best experimental conditions were as follows: when the reaction temperature was 240?,the temperature was kept for 30 min,the molar ratio of Na OH to SeO₂ was 2:1,and the addition amount of surfactant PVP was 0.2g,single-phase Cu₂Se could be obtained.Moreover,the obtained powder has a uniform morphology,mainly with a nanoplate structure.Temperature and NaOH content affect the phase composition,surfactant content and reaction temperature affect the powder morphology and size.The possible reaction equation under microwave solvothermal conditions and the nucleation and crystallization process of Cu₂Se are also given?Using microwave solvothermal method,Cu₂Se/rGO composite powder was synthesized in one step.Under microwave solvothermal conditions,one-step reduction of GO can be achieved.Compounding with GO can effectively reduce the grain size of Cu2 Se,and the in-situ growth of Cu₂ Se on the surface of GO can Effectively avoid graphene agglomeration.The microwave solvothermal with ethylene glycol as the solvent can greatly reduce the number of GO oxygen-containing functional groups,restore the conjugated structure of graphene,and obtain rGO.