Study On The Thermodynamic Properties Temperature/Crystal Surface/Size Effect Of Nano AgX?Cl/Br/I? And Nano Cu₂O

Nano-science technology is a major frontier field of interpenetration in many disciplines such as physical,chemical,material,energy,biology and medicine.Nano-phase materials exhibit many unique physical and chemical properties different from bulk materials,with its unique particle size effect,surface effect,quantum effect and macroscopic electron tunneling effect.It has been found that the surface energy of nano-materials?surface enthalpy,surface entropy,surface heat capacity,surface Gibbs free energy?can greatly influence the thermodynamics,kinetics,electrochemistry,adsorption,catalysis and sensing of nanoparticle multiphase processes.The theoretical calculation shows that the surface energy of nanocrystals with different crystal faces and sizes is different,and its value determines the chemical activity of nanocrystals.However,there are many assumptions in theoretical calculation which are far from the actual system and even the results are opposite.Therefore,it is practical significance to guide the application of nanomaterials and promote the development of nano-physical chemistry and establish the technical standards for the determination of surface thermodynamic functions of nanomaterials,if we can obtain the surface thermodynamic properties of nanomaterials and study the variation law of surface thermodynamics with particle size,crystal plane and temperature.In this paper,the model materials such as spherical AgCl,AgBr,AgI nanocrystals,Cu₂O nanocrystallines with different morphologies and single crystal faces of the same component series were synthesized.The thermodynamic properties of spherical AgCl,AgBr,AgI nanocrystals,block,octahedron,dodecahedronCu₂O,chemicalreaction microcalorimetryandadsorptionthermodynamicsmethod.The temperature effect and crystal plane effect and size of them were discussed,respectively.The main findings are as follows:1.The AgCl,AgBr,AgI spherical nanoparticles were synthesized by controlling the synthesis conditions by means of precipitation method.The morphology and phase of the products were characterized by scanning electron microscopy?SEM?and X-ray powder diffractometer?XRD?.The results showed that the crystallinity was good and the particle size distribution was uniform.The dissolution equilibrium constants of AgCl,AgBr,AgI spherical nanoparticles at five temperatures of 278.15 K,283.15 K,288.15 K,293.15 K,303.15 K were measured by electrical conductivity meter,respectively.Than calculated dissolution enthalpy,dissolution entropy,dissolution Gibbs free energy.The temperature effects of the surface Gibbs free energy,surface entropy and surface enthalpy are further studied by the thermodynamic cycle theory compared with the bulk.2.The Cu₂O nanocrystalline with cubic,octahedron,dodecahedron and dodecahedron were synthesized by controlling the reaction conditions.The nanocrystals were characterized by scanning electron microscope?SEM?and X-ray powder diffractometer?XRD?.The standard molar Gibbs free energy,standard molar enthalpy and standard molar entropy and the surface molar Gibbs free energy,surface molar entropy,crystal plane effect and temperature effect of surface molar enthalpy of{100}?{110}?{111}Cu₂O nanocrystalline systems were obtained by in situ microcalorictechnique,combinedwiththermochemicalcycle,thermodynamics principle and kinetic transition state theory.The effects of Gibbs free energy activation,enthalpy and activation entropy on the activation of{100}?{110}?{111}Cu₂O nanocrystalline were investigated.The results show that at the same temperature,the reaction rate constant is dodecahedron>octahedron>cube>block,reaction activation energy,Gibbs free energy,enthalpy of activation,entropy of reaction activation is block>cube>octahedron>dodecahedron at the same temperature.3.Using MO as the simulated molecular probe,the adsorption thermodynamic functions of different cuprous oxide microcrystals with single crystal face were studied.The thermodynamic model of copper oxide adsorption on different crystal planes was discussed by combining the thermodynamic cycle theory and the theoretical model.The results show that at the same temperature,the standard adsorption equilibrium constant and the standard molar adsorption Gibbs free energy are all dodecahedron>octahedron>cube.The order of standard molar adsorption enthalpy and standard molar adsorption entropy is cube>octahedron>dodecahedron.The standard molar adsorption enthalpy and standard molar adsorption entropy are in the order of cubic>octahedron>dodecahedron;?3?cubic?100?,octahedral?111?,dodecahedral?110?Cu₂O crystallites.The surface Gibbs free energy and adsorption activity have a significant effect.4.In this dissertation,the cuprous oxide nanoparticles of 42 nm,55nm and 67 nm were controlled by the precipitation method.The particle size,morphology and purity of cuprous oxide which had different particle sizes were represented by FESEM,X-ray diffraction.Electrochemical method measuring the electromotive force of the battery as its temperature changes,obtaining its temperature coefficient,and calculating the nanomaterial based on electrochemical theory.The thermodynamic function varies with the particle size.The results show that dispersion difference cell electromotive force the standard entropy,the standard molar formation Gibbs function,the standard molar formation surface thermodynamic function,surface Gibbs free energy,surface defects,and surface entropy of the cubic cuprous oxide nanomaterial decrease with the particle size.Increased,consistent with the deduced theoretical model.This thesis provides a new method for studying the thermodynamic function of nanomaterials,which greatly enriches the nanophysical chemistry theory and lays the foundation for the development of thermodynamic properties of nanomaterials.