Evolution of Pt Nanoparticles Supported on Fishbone-Type Carbon Nanofibers with Cone-Helix Structures: A Molecular Dynamics Study
HY Cheng and YA Zhu and PO Astrand and D Chen and P Li and XG Zhou, JOURNAL OF PHYSICAL CHEMISTRY C, 117, 14261-14271 (2013).
Molecular dynamics simulations based on a reactive force field (ReaxFF) are performed to examine the effects of the variable morphologies of fishbone-type carbon effects of the variable morphologies of fishbone- type carbon nanofibers (f-CNFs) on the microstuctures of supported Pt-100 clusters. Four f-CNF cone-helix models with different basal-to- edge surface area ratios and edge plane terminations are employed. Calculated results indicate upon adsorption of Pt-100 clusters a fraction of Pt atoms migrates from the metal particles onto the f-CNFs either to accumulate at the metal-support interface or to attain a single atom adsorption on the supports. With decreasing apex angle or introduction of H termination, the Pt atoms are more likely to be coordinated to the basal planes and the binding energies of the Pt-100 clusters to the f-CNFs are lowered, accompanied by a lower degree of the cluster reconstruction. On the contrary, if more f-CNF edge planes are exposed, a higher Pt dispersion, lower surface first-shell Pt-Pt coordination numbers, and longer Pt-Pt surface bonds are attained. Considering the interplay between the geometric and the electronic structures of transition metal surfaces, the relationship among the support morphologies, the metal-support interactions, and the catalytic properties of the active Pt clusters is eventually elucidated.
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