The Synthesis Of Noble Metal Nanoparticles And Their Alloys

The nature of nano materials will be affected by the size and shape of itself, and the synthesis of nanocrystals with different morphologies attract the interest of scientists. This dissertation focuses on prepareing noble metal nanocrystals and their alloys with the size of2nm and synthesized Pd-based nanocrystals with different shapes and studying its forming mechanism.Champer Ⅱ of this dissertation, through improved Brust-Schiffrin method, proposed a simple, fast and green method to prepare noble metals Au, Ag, Ru, Rh, Pd, Pt and their alloy. The obtained nanocrystals are uniformly dispersed in toluene and could be stable for many days. The size of the nanocrystals are about2nm. In this method the expensive phase-transfer reagent such as DODA and TOAB is not used and simplify the two-phase method to a single phase method. The green solvent ethanol replace the organic solvent such as THF, toluene and so on. NaBH4is a strong reducing reagent, it can reduce the metal salt easily and quickly. So in this experiment the reaction could occur at room temperature. All this advantages make it possible to mass production in industry.Champer Ⅲof this dissertation, proposed a new approach—the Quasi-solid-state method to synthesis Pd and Pd-Pt alloy. In this method only small amount of solvent participate in the reaction and by grinding to make the mixture uniformtive. At150℃the reaction generate nanocube, nanooctahedron Pd and octahedron, truncated octahedron, dendrite-like Pd-Pt alloy. Only trace amount of solvent involved in the reaction, so it is easily evaporated off and the system become solid-state. Based on the experiment results we proposed the possible mechanism. In the initial reaction stage it generate a large number of small nanoparticles and the small nanoparticles aggregate with each other to form nanocrystals with different morphologies under different conditions. But the aggregation will not stop even when the tiny amount solvent evaporate off.