Pd-Co Bimetallic Nanoparticles Supported On Graphene As A Highly Active Catalyst For Carbon-Carbon Coupling Reactions

As a new carbon material, graphene own many excellent features, such as electricalproperties, thermal stability and large specific surface area and so on. Graphene wasused to be the ideal substrates to host metal nanoparticles.Homogeneous palladium (II) complexes are one of the most popular catalysts usedto catalyze carbon–carbon coupling reactions. However, the homogeneous catalysisowns numerous drawbacks, especially, high cost and non-reusability. Nanoparticles withhigh catalytic activity seem to be one promising option to replace the homogeneouscatalysis for these reactions. To reduce the usage of noble material, the hybrid structurealloyed by Pd and non-noble metals were designed and synthesis. In many cases, thesynthesized Pd/non-noble-metal catalysts not only shows a combination of theproperties associated with two different metals but also have an enhancement in specificproperties due to synergistic effects. However, very tiny nanoparticles usually addproblems in catalyst separation and also induce agglomeration due to high surfaceenergy, leading to the decrease in catalytic efficiency. Therefore, the problem may besolved by using graphene for supported bimetallic nanoparticles.We disclosed that Pd-Co bimetallic nanoparticles can be dispersed on G withcontrollable size of nanomaterial by a chemical reduction method and used for couplingreactions. With the characterization of X-ray diffraction, X-ray photoelectronspectroscopy, transmission electron microscopy and Raman spectrum, the compositionof resulting Pd-Co material was well-dispersed on graphene and identified to be alloystructural.The catalytic performances are evaluated in Sonogashira-, Suzuki-type reactions.Compared with the traditional homogeneous catalysts, PdCo/G showed higher activity.Furthermore, this efficient catalyst could be used repetitively by a magnet for five times,showing good potential in future industrial applications.Combined both efficiency of a homogeneous catalyst and the durability of aheterogeneous catalyst, the Pd-Co/G composites provide great potential for G to supportother bimetallic nanoparticles such as Ni and Cu, which offer more opportunities fordesigning new catalysts.