Coarsening of Pt nanoparticles on amorphous carbon film

► The coarsening of Pt nanoparticles on amorphous carbon film was studied after annealing between 200 °C and 300 °C. ► An in-situ annealing experiment in a transmission electron microscope reveals two coarsening stages. ► During the first two hours of annealing, nanoparticles ripening is dominated by Smoluchowski ripening. ► During the second coarsening stage Pt nanopaticles coarsening proceeds via surface Ostwald ripening. ► The surface diffusion of Pt atoms on an amorphous carbon was deduced.