Pd/graphene nanocomposite as highly active catalyst for the Heck reactions

The graphene-supported Pd (Pd/graphene) catalyst was synthesized using the graphene oxide and Pd salt as precursor; then both Pd nanoparticles and graphene oxide were chemical reduced by hydrazine hydrate. Transmission electron microscope and powder X-ray diffraction analysis indicated the Pd nanoparticles, which supported on the surface of the graphene sheets with the size of 2-6 nm. The catalytic activity of Pd/graphene was investigated in Heck coupling reactions with activated and non-activated aryl substrates. The Pd/graphene composites exhibit an excellent catalytic activity, low Pd leaching, and reuse ability of at least five recycles in air for the Heck carbon-carbon coupling reaction. The experimental results showed the graphene sheets were great support for ligand-free Pd catalyst. (C) 2014 Elsevier B.V. All rights reserved.