16/06/2017

Growing anisotropic crystals at the nanoscale

Title: Growing anisotropic crystals at the nanoscale
Authors:

Liz-Marzán L., Grzelczak, M.

Journal: Science, 2017, 356, 1120-1121

Technological prospects of metal nanoparticles (NPs) have stimu¬lated intense research activities into their growth mechanisms to pre¬dict shape, size, and crystallinity. Of high interest are low-symmetry nanocrystals (NCs), which exhibit high-energy facets that are relevant in catalysis or plasmonic properties that are attractive for applications in areas such as biomedi¬cine. Rod-like shapes are in principle most challenging because the high-symmetry face-centered cubic (fcc) lattice of the met¬als of interest, such as gold, tends to form high-symmetry, compact NCs. To promote shape anisotropy, nucleation and growth are usually separated in the so-called seed-mediated growth, in which a metal precur¬sor is reduced on preformed seeds in the presence of shape-directing additives. The growth of nanorods is a nonequilibrium process and remains poorly understood, which accounts for their limited reproduc¬ibility and yield. The required control over the crystal habit of the seeds and the effect of additives will necessitate insights from theoretical modeling as well as character¬ization, especially by state-of-the-art trans¬mission electron microscopy (TEM).