TEM and Electron Tomography Imaging of Pt Particles Dispersed on Carbon Nanospheres

Three-dimensional (3D) observation of Pt nanoparticles on the surface of carbon nanoparticles, one of the important catalyst systems for energy storage such as fuel cells, was carried out by using an electron tomography system attached to a transmission electron microscope (TEM). In the Pt/carbon sample preparation process, pristine and graphitized carbon nanospheres (CNSs, 200 nm average diameter) were immersed into H(2)PtCl(6) solution, followed by a heat-treatment at 493 K. According to the electron tomography technique, we confirmed that crystalline Pt particles (2-3 nm) were homogeneously dispersed on the whole surface of pristine CNSs, while on the graphitized CNSs Pt was aggregated on the ridgeline of the polyhedronized CNS particles or on the connecting surface between two CNS particles. Dependence of Pt dispersion as shown was discussed with the distribution of surface defects of CNS particles.