Studies On The Solvothermal Synthesis And Physicochemical Property Of Co/Co₃O₄ Nanomaterials

Co/Co₃O₄ nanomaterials show novel physicochemical properties in the field of electricity, magnetism, phonic, optics and thermology. Thus they have great potential in the wide application of biosensing, data storage, catalysis, drug delivery and lithium-ion battery. Since the properties and application of nanomaterials are deeply influenced by their phases, dimensions and size, microstructures as well as morphologies. Many scientists focus on development of nanomaterials with different dimension, size and morphologies, and then do massive research projects in exploring their physicochemical properties. Therefore, this dissertation is aimed at preparation of Co/Co₃O₄ particles with different morphologies through feasible and facile solvothermal methods, and exploring impact regulations of microstructures on their physicochemical properties such as magnetism, catalysis and electrochemistry. In addition, Co/Co₃O₄ particles with 3D construction showing excellent catalytic and electrochemical properties were prepared through optimal experiments. All the research process could be divided into four stages as follows:Choosing Co Cl2·6H2O as cobalt source, Na OH as alkali source and ethanediol as organic solvent to process solvothermal reaction. Cobalt particles with different morphologies were obtained by adjusting the content of cobalt ions and sodium hydroxide, reaction time and temperature, and were analyzed about their magnetic and catalytic properties. Above all, we have got different particles morphologies by tuning experiment conditions, and thus achieved wide tunable range of saturation magnetization of Co particle successfully. Besides, hexagon plate Co particles could tune down the thermal decomposition temperature of ammonium perchlorate from 425 ℃ to 310 ℃.In order to prepare Co₃O₄ particles with 3D hierarchical structure, we tried complicated mixed solvothermal method. Sodium oleate, Co Cl2·6H2O, oleic acid and ammonium oleate were put into mixed solvent（deionized water/ethanol/normal hexane） and reacting for 3 h at 180 ℃. Then the 3D hierarchical structure was obtained after annealing the precursor at several temperatures. The saturation magnetization of Co₃O₄ particles influenced by annealing temperature was researched, and this material could decline the thermal decomposition temperature of AP to 356 ℃.The third stage was to try feasible and facile solvothermal method to prepare Co₃O₄ particles with 3D hierarchical structure, C4H6 Co O4·4H2O was dissolved in deionized water/ 1, 2-propanediol mixed solvent, keeping p H at 10 by Na OH, then reacted for 24 h at 220 ℃. Then 3D flower-like Co₃O₄ particles were obtained by annealing precursor at different temperatures. Products annealed at 280 ℃ showed remarkable catalytic property, declining the thermal decomposition temperature of AP to 245 ℃.Following the third stage, keeping other reaction parameters constant, Just changing Na OH with NH3·H2O, we obtained 3D flower-like Co₃O₄ particles assembled by more slim nanosheets. And taking them as the cathode of lithium ion battery, their specific capacity still kept above 1200 m Ah/g after 50 charge-discharge-cycle numbers under the 296 m A/g current intensity condition, much higher than the theratical value 890 m Ah/g.