Synthesis And Catalytic Properties Of Palladium-based Nanoalloy

Noble-metal nanoparticels in various applications have been widely reported owing to their excellent catalytic properties. Scientists have found that compared to other precious metals, palladium has high stability and excellent catalytic effect, so it can be used to catalyze many organic reactions. More importantly, with the improvement of synthetic methods and the development of single-crystal diffraction techniques, noble-metal(Pd,Pt,Au,Ag) with non-noble-metal(Fe,Co,Ni,Cu,etc.) alloying of the nanoparticel materials have attracted tremendous research attention on the morphology, structure, size,composition,and catalytic properties. However, the catalyst which has special morphology, uniform size, recycled, efficient catalytic performance is still very limited. To date, the bimetallic alloy catalyst with different geometric morphology, electronic structure and synergistic effect is most representative of the catalytic system. Scientists have found that the alloys as the catalysts with superior catalytic performance were widely used in organic synthesis, electrocatalysis, sensors and clinical diagnostics. The multi-functional catalyst not only has the nature of individual metal but also combines the properties of the individual constituents but also shows an enhancement in specific properties because of the synergistic effects. The alloy reduce the utilization of precious metals because of alloying the non-metal and it improves the catalytic efficiency because of the synergistic effects. Furthermore, the alloy accord with the requirement of green chemistry by using the properties of the recycling. In conclusion, the alloy catalyst is a research hotspot in the field of metal organic catalysis. In this article, we synthesized monodispersed alloy and catalyzed in organic reactions:investigating the morphology and catalytic activity. The main contents are as follow: 1. A series of Pd-Ni nanoalloy catalysts with tunable compositions were successfully prepared by a co-reduction method. The use of oleylamine as both solvent and reductant and triphenylphosphine (TPP) as ligand was very effective for the preparation of the monodispersed nanoalloy. The Pd-Ni alloy NPs have uniform sizes and the compositions can be tuned by varying the molar ratios of the precursors. The classical Miyaura-Heck coupling reaction was chosen to verify the catalytic activity of the Pd-Ni nanoalloy. From the experimental results, Pd1Ni1 alloy showed better catalytic activity than equal amounts of sole Pd catalyst and the series of Pd-Ni nanoalloy, which was also suitable for different substrates in the Miyaura-Heck reaction.2. In this paper, the Pd-Ag nanoalloy catalyst with uniform size and morphology was successfully synthesized by one-step synthetic strategy. The structure and morphology of Pd-Ag nanoparticles were characterized using X-ray diffraction (XRD), Transmission electron microscopy (TEM), High resolution transmission electron microscopy (HRTEM), respectively. The results shown that the morphology of Pd-Ag could be controllabled by changing the temperature. On the basis, The organocatalysis performance of the Pd-Ag nanoparticles was investigated. When the morphology of the Pd-Ag was spherical, the yields of Miyaura-suzuki reactions were the best.