Kinetically Controlled Growth And Shape Formation Mechanism Of Platinum Nanoparticles

Abstract Many studies on colloidal nanoparticles have focused on the control of nanoparticle size and correlated this to the catalytic activity. Recently, our group has reported for the first time a technique that controlled the shape distribution of Pt nanoparticles. This was done by varying the concentration of the capping polymer and the platinum ion ratio used in the reductive synthesis of colloidal nanoparticles at room temperature. Cubic, tetrahedral and truncated octahedral (TO) particles have been prepared, making it possible to study the catalytic activities of nanoparticles with different shapes and facets. Using transmission electron microscopy (TEM), we imaged the shapes and determined the shape distribution of platinum nanoparticles at different stages of their growth as a function of time. The small nanoparticles formed during the early stages of growth or at high polymer concentration displayed distributions with a dominance of tetrahedral shapes (see Figure la).