Deposition and Characterization of Platinum Nanoparticles on Highly Orientated Pyrolytic Graphite

Pt nanoparticles were synthesized by polyol method and then deposited on a highly orientated pyrolytic graphite (HOPG) substrate. They also were obtained by direct reduction of chloroplatinic acid on HOPG in a H-2 flow and by immersing the graphite electrode into a platinum plating solution, 0. 1 mM H2Cl6Pt and 0.1 M H2SO4 solution. The density of particles as well as their dimension depend in this case on the time of immersion in the hexachloroplatinic solution. Pt nanoparticles formed for these methods are mainly quasi hemispherical small Pt nanoparticles in size. The characterization of these systems was studied by high angle annular dark field (HAADF) technique and transmission electron microscope (HRTEM). The combination of these experimental techniques allowed, the determination of the structure and the distribution of Pt nanoparticles on HOPG. A rotation between the layers of HOPG was observed in the direction perpendicular to the basal plane by effect of heating in H-2.