Molecular dynamics simulations were used to investigate the mobility and morphology of platinum nanoparticles supported on carbonaceous materials (table 7). The embedded-atom method was used to model Pt-Pt interactions. The Pt-C interactions were modelled using the Lennard-Jones potential. Carbon atoms were treated as rigid. The supports considered included a single graphite layer as well as carbon nanotubes, regarded as bundles. The goal was to assess the effect of the substrate morphology on the properties of the metal nanoparticles. The properties of interest included the mobility and morphology of the supported nanoparticles. The results showed that the diffusion coefficients of Pt nanoparticles on carbon nanotube bundles were an order of magnitude lower than those of Pt nanoparticles supported by graphite. Density profiles, radial distribution functions, and average coordination numbers were calculated to study the structure of the supported nanoparticles. Platinum nanoparticles deposited on carbon nanotubes were structurally different from those deposited on graphite. In particular, they were characterized by a lower average coordination number than those supported by graphite. These results indicate that the catalytic properties of supported Pt nanoparticles could be tuned by changing the substrate and may provide a partial explanation of recent experimental studies according to which metal nanoparticles deposited on carbon nanotubes make effective catalysts.

Morphology and Diffusion Mechanism of Platinum Nanoparticles on Carbon Nanotube Bundles. Morrow, B.H., Striolo, A.: Journal of Physical Chemistry C, 2007, 111[48], 17905-13

Table 7

Activation parameters for the diffusion of a

249-atom Pt cluster on various substrates