Colloidal synthesis of pt nanoparticles: on the formation and stability of nanowires.

Catalytic properties of Pt nanoparticles can significantly depend on the crystallite shape, which renders shape control an important aim in the chemical synthesis. Starting from a colloidal synthesis of quasispherical Pt nanocrystals capped with dodecylamine ligands, systematic variations of different synthesis parameters were performed in the present work in order to obtain Pt nanowires. Mechanistic investigations revealed that nanowires can form by aggregation of quasispherical particles. The process of wire formation was found to be influenced by parameters such as the concentration of the stabilizing ligands on the particle surface. Furthermore, the thermal stability of the obtained nanoparticles was examined. The nanowires were found to be stable up to approximately 140-160 degrees C. In this temperature range a structural transition to a more spherical crystallite shape occurred, which can be understood by thermodynamic considerations.