Morphology and diffusion mechanism of platinum nanoparticles on carbon nanotube bundles

BH Morrow and A Striolo, JOURNAL OF PHYSICAL CHEMISTRY C, 111, 17905-17913 (2007).

DOI: 10.1021/jp071474o

Molecular dynamics simulations have been used to investigate the mobility and morphology of platinum nanoparticles supported on carbonaceous materials. The embedded-atom method was used to model Pt-Pt interactions. The Pt-C interactions were modeled using the Lennard-Jones potential. Carbon atoms were treated as rigid. The supports considered include a single graphite layer as well as carbon nanotubes, regarded as bundles. The goal of our work is to assess the effect of the substrate morphology on the properties of the metal nanoparticles. The properties of interest include the mobility and morphology of the supported nanoparticles. Our results show that the diffusion coefficients of Pt nanoparticles on carbon nanotube bundles are 1 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,are structurally different from those deposited on graphite. In particular, they are characterized by a-lower average coordination number than those supported by graphite. These results ind icate that the catalytic properties of supported Pt nanoparticles can 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.

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