Preparation Of Nanomaterials By Using Liquid Glow Discharge Plasma

In recent years,nanomaterials(NMs)have attracted much attention due to their unique characteristics.The traditional preparation methods,such as hydrothermal method,chemical vapor deposition method,sol-gel method and electrochemical method,have mostly serious pollution,expensive equipment and complex device.Plasma,because of its environmental protection,has developed in various fields.A new branch of plasma is rapidly development for interactive synthesis of nanoparticles(NPs)through plasma liquid interaction.Plasma liquid interaction provides a novel plasma-liquid interface where many physical and chemical processes can occur.Arc discharge plasmas,high-voltage pulse discharge plasmas,and microwave-induced plasmas are expensive and complicated in apparatus,required gas protection,and required high energy.In this thesis,liquid cathode glow discharge plasma(LCGDP)and liquid diaphragm discharge plasma(LDDP)were used to prepare the Cu O NPs,h-Mo O3 NPs,Ag NPs and Zn O NPs.This thesis is divided into six chapters:Chapter 1:The development of plasma-liquid interaction synthesis of nanomaterials and the reaction of plasma liquids in the interactive synthesis of nanomaterials are reviewed.The mechanism of the preparation of nanomaterials by liquid glow discharge plasma and the synthesis method are briefly summarized.Chapter 2: In the Na NO3 solution,the Cu O NPs were successfully prepared through the liquid cathode glow discharge plasma(LCGDP),in which the platinum tip was used as the cathode,the copper was the anode and cetyltrimethylammonium bromide(CTAB)was used as the surfactant.The structure and morphology of the samples were characterized by FT-IR,XRD,SEM and TEM.Through invesitaging the current-voltage curve,the liquid cathode glow discharge plasma emission spectrum,the change of the solution p H,and the voltage change,the optimum voltage was determined to be 300 V and the best quality of CTAB was 0.15 g.The synthesis mechanism and the growth mechanism of Cu O NPs were proposed.The analysis showed that the prepared product is of high purity and is a spindle-shaped nanoparticle.The Cu O NPs have a spindle structure that length is 250-300 nm andwidth is 80-120 nm.Each spindle-shaped nanostructure is connected by one another that crystal composition,its length is about 20-40 nm.Chapter 3: In this part,a one-step method for the synthesis of six prismatic h-Mo O3 nanoparticles(NPs)via liquid cathode glow discharge plasma(LCGDP)technique was presented,in which 2.0 g/L Na2SO4 solution was used as electrolysis,and platinum needle point and Mo wire were used as cathode and anode,respectively.When a sufficient high voltage(> 230 V)was applied in the conventional electrolysis,the glow discharge plasma was produced in the solution between the Pt needle point and the electrolyte around it.Then,the Mo wire of anode was gradually consumed and plenty of black Mo O3 NPs appeared.The structure and morphology of Mo O3 NPs were characterized by FT-IR,XRD,SEM and TEM.The preparation mechanism of the Mo O3 NPs under LCGDP was proposed.The results showed that six prismatic h-Mo O3 NPs are obtained at 230-300 V discharge voltage.The average particle diameters of h-Mo O3 NPs are about 200-400 nmwide and 1.0-2.7 ?mlong.The as-prepared products have high purity.Chapter 4: In the Ag NO3 solution,the Ag NPs were successfully prepared through the liquid cathode glow discharge electrolytic plasma(CGDEP),in which the platinum tip was used as the cathode,the silver plate was the anode,and cetyltrimethylammonium bromide(CTAB)was used as the surfactant.The structure and morphology were characterized by XRD,SEM and TEM.Through studying the current-voltage curve,the liquid-phase cathode glow discharge plasma emission spectrum,the change of the electrolyte p H,the voltage change,and the quality of the added CTAB,the optimum voltage was determined to be 350 V,andbest quality surfactant was 0.15 g.The analysis shows that the prepared product is of high purity.When there is no surfactant,the product is a silver nanorod with a diameter of about100 nm and a length of between 650 and 2150 nm.When 0.01 g of CTAB was added,the product was a silver nanoball with a diameter of 300-900 nm.Chapter 5: The Zn O NPs were successfully prepared by the liquid diaphragm discharge plasma(LDDP)in Na2SO4 solution,in which the zinc was used as anode and cathode.The structure and morphology of products were characterized by FT-IR,XRD,SEM and EDS.Through invesitaging the current-voltage curve,dischanrge voltage and change of the electrolyte p H,the optimum voltage was 570 V.In addition,the synthesis mechanism was also proposed.The analysis showed that the prepared product is of high purity and like a banana rod.Chapter 6: Advantages for the preparation of nanomaterials by liquid glow discharge plasma technique were summarized,and the future research directions were put forward.