Temperature-Dependent Change in Shape of Platinum Nanoparticles Supported on CeO2during Catalytic Reactions

The temperature dependence of the shape of Pt nanoparticles supported on CeO2 for CO oxidation was investigated using environmental transmission electron microscopy. Pt nanoparticles in CO/air become round at room temperature (when catalytic activity is low), while they become partially faceted at elevated temperature (when the catalytic activity is high). Based on a comparison between the shapes of the Pt nanoparticles in vacuum, N2, O2, CO, and CO/air at room temperature, 100, and 200 °C, we propose that the change in shape of the Pt nanoparticles is induced by the adsorption of CO molecules and O atoms.