Kinetic modelling of the shape-dependent evolution of faceted gold nanoparticles

Abstract

Gold nanoparticles offer a range of highly desirable properties that are intrinsically linked to their size and shape, thereby providing tantalising opportunities for tailoring the nanomorphology for specific applications. The stability of different shapes has been mapped on a nanoscale phase diagram, but there are numerous experimental observations in the literature that do not conform to this prediction. This inconsistency has been attributed to dominant kinetic influences, but testing this hypothesis has remained challenging using conventional experimental or computational techniques. Presented here are results of a shape-dependent kinetic theory of nanomorphology, for modelling the evolution of facetted gold nanoparticles, and exploring the edifying relationship between seed (or nucleus) size and temperature. The study concludes that the frequent observation of icosahedral nanoparticles at thermodynamically-forbidden sizes is due entirely to their superior rate of coarsening, and that the shape of the thermodynamically preferred motifs can be moderated by controlling conditions during the early stages of formation.