Solvothermol Synthesis And Characteration Of Monodispersed Metal Nanomaterials

Due to the significant use of uniform nanometer sized particles in fundermental studies and technological application, they have been intensively studied in recent days. The controlled synthesis of the nanoparticle size and monodispersity is a key in the research of their properties and application. Solvothermal synthesis-reducing metal salts in the presence of surfactants and solvents--is the most general method employed for the synthesis of uniform sized monodispersed metal nanoparticles. The size of the as-prepared metal particles can be controlled by the capping ligand in the solution, reactive ratio, temperature, time and so on. Monodispersed magnetic nanoparticles can be applied in catalytic, ferrofluids, magnetic refrigeration systems, magnetic carrier for drug targeting and high-density information storage. By far, many colloid chemistry synthetic methods of monodispersed magnetic nanoparticles, such as nickel, cobalt, gold, platinum, palladium,γ-Fe₂O₃, Fe₃O₄, MnO, Mn₃O₄, CoFe₂O₄, NiPt, and their property studies have been reported by people. Uniform sized monodispersed nickel nanoparticles and nanorods have been synthesized, but the precursors of nickel and capping ligand system are very complex, and the reducing reagent such as NaBH₄, will easily introduce impurity to the system. Here in our work, different sized, well monodispersed nickel and platinum nanoparticles and their properties are synthesized by controlling reaction conditions, and using simplified capping ligand system and inorganic salt which is safer and lower toxicity.1. Synthesis of monodispersed nickel nanoparticles with nickel acetate acting as precursorIn this work, the reaction system is greatly simplified by using single surfactant system, in which surfactant hexadecylamine (HDA) also acts as solvent, reducing agent, and surfactant. The precursor of nickel is nickel acetate, which has safer and lower toxic properties. In the presence of N₂ atmosphere, monodispersed nickel nanoparticles with different size and different crystal phases are synthesized by controlling reaction conditions. The nanoparticles are characterized by TEM, HR-TEM, XRD, TG, IR, and SQUID. The influence of the reaction temperature, reaction time and the molar ratio of reagents are also studied and the process of reaction is discussed.2. Synthesis of nearly monodispersed nickel nanoparticles with nickel chloride acting as precursorIn this work, palladium chloride acting as palladium precursor, HDA reaction system is used to synthesize nearly monodispersed palladium nanoparticles. It is found that reaction conditions such as molar ratio of reagents, reaction temperature and reaction time can influence the size of the nanoparticles. Especially different atmosphere can induce different shapes of the nanoparticles such as nanoparticles and nanoplatelets. By changing reaction time and disperse system, the nearly dispersed nanoparticles can be obtained on the copper grid.