Adv. Mater. http://doi.org/rb5 (2014)

Credit: © 2014 WILEY

Crystal facets result from anisotropic growth along different crystallographic directions and, as a consequence, do not usually exist for polycrystalline materials that have no long-range order and grow isotropically. Now, Ullrich Steiner and colleagues show that faceted platinum particles (pictured), which are inherently polycrystalline, can be isolated following electrochemical synthesis within mesoporous polymeric templates with double-gyroid morphology. Without such a template, spherical platinum particles are produced. Faceted platinum particles with well-defined symmetries are made when the template has large double-gyroid monodomains, however, if the double-gyroid morphology has randomly orientated multi-domains, an irregularly faceted particle is formed. The particles made within the monodomain templates are tetrahexahedral in shape, with 24 equal faces. Steiner and colleagues use a numerical model to explain the formation of the faceted particles and with the aid of microscopic analysis, report a nucleation–coalescence mechanism in which the growth front progresses along the centre of the channels of the template. This causes a slowing of growth in all directions — in particular, in the 110 direction, yielding the tetrahexahedra observed.