A simple process for decorating graphene sheets with well-dispersed Pd nanoparticles was reported. Via the in situ formation and adhesion of Pd nanoparticles to thermally exfoliated graphene sheets suspended in a solvent, a Pd/exfoliated graphene composite was prepared and characterized by transmission electron microscopy, X-ray photo-electron spectroscopy, and Brunauer-Emmett-Teller surface area analysis. The migration and aggregation of Pd nanoparticles on the graphene sheets was directly observed by scanning transmission electron microscopy. As the composite was heated to 700C, there was little movement of the Pd nanoparticles; on heating to 800C, well below the melting temperature, the Pd nanoparticles began to migrate, coalesce, and agglomerate to form larger particles. The aggregation behavior was further confirmed by X-ray diffraction analysis of the Pd/exfoliated graphene composite before and after being annealed at 800C. The graphene sheets provided a real-time imaging platform with nanometer-scale thickness to study the thermal stability and migratory behavior of nanoscale materials.

Decoration, Migration, and Aggregation of Palladium Nanoparticles on Graphene Sheets. Jin, Z., Nackashi, D., Lu, W., Kittrell, C., Tour, J.M.: Chemistry of Materials, 2010, 22[20], 5695-9