In-situ liquid cell transmission electron microscopy investigation on oriented attachment of gold nanoparticles

Abstract

Inside a liquid solution, oriented attachment (OA) is now recognized to be as important a pathway to crystal growth as other, more conventional growth mechanisms. However, the driving force that controls the occurrence of OA is still poorly understood. Here, using in-situ liquid cell transmission electron microscopy, we demonstrate the ligand-controlled OA of citrate-stabilized gold nanoparticles at atomic resolution. Our data reveal that particle pairs rotate randomly at a separation distance greater than twice the layer thickness of adsorbed ligands. In contrast, when the particles get closer, their ligands overlap and guide the rotation into a directional mode until they share a common {111} orientation, when a sudden contact occurs accompanied by the simultaneous expulsion of the ligands on this surface. First-principle calculations confirm that the lower ligand binding energy on {111} surfaces is the intrinsic reason for the preferential attachment at this facet, rather than on other low-index facets.

In Situ Transmission Electron Microscopy Study of Nanocrystal Formation for Electrocatalysis

“…The both of above two works revealed the interaction of nanoparticles during the growth process which are significant to understand the growth kinetics during the formation of single metal electrocatalysts. Except for Pt, the oriented attachment also existed during the formation process of other metals like Au, which confirmed the generality of this behavior in the formation of metal nanoparticles. It has been demonstrated that the coalescence and attachments could lead to the formation of nanoparticle and nanowires, which generally depends on the diffusion of the atoms: fast diffusion is in favor of nanoparticles; or insufficient diffusion tends to nanowires.…”

Negative‐Imaging of Citrate Layers on Gold Nanoparticles by Ligand‐Templated Metal Deposition: Revealing Surface Heterogeneity

“…Those events include quantum tunneling, charge transfer, chemical interfacial damping, and surface dipole formation. In the view of recent quantum‐tunneling studies in the nanoparticle gap less than 1 nm, for example, the presence of adatoms or altered molecular orientation on the surface of gold nanoparticles may cause an error in the estimated distance of nanoparticle gap up to 0.5 nm compared to a simplified surface model . A precise description on nanoparticle surfaces will provide plausible explanations of puzzling experimental observations.…”

Graphene Liquid Cells Assembled through Loop‐Assisted Transfer Method and Located with Correlated Light‐Electron Microscopy

“…To load pocket and crease cells, a droplet of 10 × 10 −3 m solution of HAuCl 4 was placed on the TEM grid prior to transfer of the graphene top layer by the LAT method. The formation of Au nanoparticles from HAuCl 4 solution was chosen as a test reaction because it is a well‐documented procedure that has been extensively characterized in literature . After 10 s of beam exposure, nanoparticles of varying sizes had formed in all liquid cells, with high contrast regions being, indeed, pockets of encapsulated liquid ( Figure a–c).…”