An approach was presented which combined in situ transmission electron microscopy, electron tomography and molecular dynamics calculations for assessing the evolution of Pt nanoparticles deposited onto few-layer graphene supports. Spherical Pt nanoparticles with average sizes of 2nm located preferentially at the support topographical defects (e.g., steps and edges) diffuse and coalesce along these defects, such that, after annealing to 700C, the nanoparticles were located exclusively here. Their dispersion remained significant; only the particle size distribution changed from mono- to bimodal. This statistical variation was discussed herein by reviewing fundamental issues such as the nanoparticle-support interaction and nanoparticle faceting, diffusion, and subsequent sintering in the high-temperature range. Fundamental molecular dynamics simulations were reported here as reinforcements of the experimental findings and as a means to provide deeper insight into the phenomenological issues behind the behavior of the system investigated.

On the Evolution of Pt Nanoparticles on Few-Layer Graphene Supports in the High-Temperature Range. Moldovan, M.S., Bulou, H., Dappe, Y.J., Janowska, I., Bégin, D., Pham-Huu, C., Ersen, O.: Journal of Physical Chemistry C, 2012, 116[16], 9274-82