Shape Control of Platinum Nanoparticles

The synthesis of shape controlled platinum nanoparticles has been investigated through an organometallic approach starting from the complex Pt₂(dba)₃ and using a long alkyl chain amine, hexadecylamine (HDA), as stabilizer. The influence of the experimental parameters (reactive gas and solvent nature, stabilizer/metal ratio, reactants concentration, temperature) on the shape of the Pt nanoparticles has been studied. Various shaped platinum nanostructures such as isolated nanoparticles, dendrites or crystalline nanowires were obtained, depending on the reaction conditions. This method takes profit of the mild conditions of chemistry in solution and allows obtaining regular nanostructures, most of them being homogeneous in shape as well as in size (isolated nanoparticles) or diameter/length (nanowires). Transmission electron microscopy and wide‐angle X‐ray scattering were used as characterization techniques. Beside the Knight‐shift effect of platinum, NMR solution investigations clearly evidenced the coordination of the amine at the Pt particles surface and its mobility. This mobility, increased when H₂ is used as reactive gas for the precursor decomposition, favors the particles coalescence into nanowires. This phenomenon is also favored by the “soft” template character of the amine in particular in toluene solution.