From Gold Nanoseeds to Nanorods: The Microscopic Origin of the Anisotropic Growth

Abstract

Directly manipulating and controlling the size and shape of metal nanoparticles is ak ey step for their tailored applications.I nt his work, molecular dynamics simulations were applied to understand the microscopic origin of the asymmetric growth mechanism in gold nanorods.D ifferent factors influencing the growth were selectively included in the models to unravel the role of the surfactants and ions.I nt he early stage of the growth, when the seed is only af ew nanometers large,adramatic symmetry breaking occurs as the surfactant layer preferentially covers the (100) and (110) facets, leaving the (111) facets unprotected. This anisotropic surfactant layer in turn promotes anisotropic growth with the less protected tips growing faster.W hen silver salt is added to the growth solution, the asymmetry of the facets is preserved, but the Br À concentration at the interface increases,r esulting in increased surface passivation.

One-Dimensional Metal Nanostructures: From Colloidal Syntheses to Applications

“…The preservation of these metastable facets, however, has long been poorly understood. Recent computational modeling suggests that the coverage density of CTA + on {110} (1.49 molecules/nm 2 ) is identical to that on {100} (1.49 molecules/nm 2 ) and higher than that on {111} (1.31 molecules/nm 2 ) . As such, stabilizing these facets may have led to the extension of {110} facets on side surfaces of AuNRs.…”

Selective shortening of gold nanorods: when surface functionalization dictates the reactivity of nanostructures

“…Interestingly, the identified distribution of citrates over gold NR facets and their role in the anisotropic dissolution is very similar to the identified distribution of surfactants and their role in the anisotropic growth phenomena. Indeed, using molecular dynamic simulations, Sulpizi et al 28 have identified the role of surfactant layer that preferentially covers the (100) and (110) facets, leaving the (111) facets unprotected. This inhomogenous surfactant layer promotes anisotropic growth with the less protected tips growing faster, which explains the shape of NRs.…”

“…Moreover, many MD works focused on the interaction between surfactants and metal surfaces have been performed to explain the growth of anisotropic nanostructures coated with ligands such as citrate, piptide, CTAB …. [28][29][30][31] However, to our knowledge such theoretical approaches have never been used to reveal the effect of surface functionalization on the dissolution processes of nanoparticles.…”

Halide-Induced Step Faceting and Dissolution Energetics from Atomistic Machine Learned Potentials on Cu(100)

“…In deposition and dissolution reactions, adsorbates can act as intermediates, site blocking spectators, and/or structure-altering mediators of reactivity. Adsorbate guided dissolution can be applied to etch highly anisotropic structures, but similar reaction conditions can lead to undesired effects, such as localized corrosion. , Likewise, adsorbates impact additive processes such as nanoparticle synthesis − and the fabrication of multiscale microelectronic interconnects …”