Synthesis and characterization of graphene-supported metal nanoparticles by impregnation method with heat treatment in H2 atmosphere

Graphene as a support for various metal nanoparticles was synthesized through a wet-chemical method combined with thermal exfoliation of graphite. The 60 wt% metals (Pt, Pd, Rh, Ru, Sn, and Ni) supported on the graphene materials were prepared by impregnation method with a subsequent heat treatment in H2 atmosphere. Physicochemical analyses such as X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) were employed to investigate the structural and electronic properties of the deposited metals on the graphene material. The metal nanoparticles were finely dispersed on the graphene support. The graphene-supported Pt, Pd, Rh, and Ru materials appeared to be metallic phase, however, the Sn phase showed an oxide state. The graphene-supported Ni revealed a core/shell-like structure of oxide and metallic phases at the surface and core part, respectively. The graphene-supported Pt and Ni were further heat-treated to investigate structural change of the supported nanoparticles, in which the particle size became larger and their crystallinity of the Pt and Ni was enhanced with increasing treatment temperatures.