Shape Control in Gold Nanoparticles by N-Containing Ligands: Insights from Density Functional Theory and Wulff Constructions

Abstract

The controlled growth promoted by the use of ligands can affect the structural properties of nanoparticles, preferential growth and most likely exposed facets in their final shape. The chemistry is deeply dominated by the close relationship between both the interaction of the ligands and the metal structure. In the present work, we have illustrated the change in the nanoparticle shape as a function of a series of nitrogen bases. Particularly, we have employed Density Functional Theory to obtain the interaction energies of a series of nitrogen containing bases to gold surfaces with different orientations. The adsorption strength is found to correlate with the HOMO position of the ligand thus providing a fast screening tool for this property. Moreover, for small N-bases with high N content we have found that the shape can be tuned as a function of the coverage and the final structure at high coverages severely departs from that of bare gold nanoparticles. We have found variations in the different extension of the facets that can be further employed in obtaining structure sensitivity and the right chemical and catalytic performance.

Approaches to modelling the shape of nanocrystals

“…While filling a shape with model atoms is not by itself a Wulff construction, it is useful in a variety of contexts not covered by the continuum result. The resulting atomistic models of nanocrystals have been used for modelling surface adsorption [ 59 – 61 ] and active sites for catalysis [ 54 – 56 , 62 ]. Moreover, it could also be useful in the case of very small particles, if they retain the same packing as the bulk.…”

Gold Catalysis for Selective Hydrogenation of Aldehydes and Valorization of Bio‑Based Chemical Building Blocks

“…Unfortunately, it was not possible to verify the same effect after adding other ligands ( Table 1, entries 1 and 4-8), in fact in some cases a decrease in the catalytic activity was noticed, which might occur due to strong adsoption of the ligands to the gold surface, blocking the catalytic active sites. 8,29 Importantly, a blank experiment without any ligand led to 60% conversion of 1a, giving us insights to believe that the carbonyl compound might assist gold in the heterolytic H 2 dissociation, leading to the formation of a hydride on the metal surface and a proton which bonds to the carbonyl oxygen. 11,27 Hydrogenation studies were continued, under different reaction conditions, with ligand L3 (2,4,6-trimethylpyridine or collidine) that reached higher conversions.…”

Text-mined dataset of gold nanoparticle synthesis procedures, morphologies, and size entities

“…However, these approaches come with inherent tradeoffs between the resolution of atomic interaction and computational tractability. For example, calculations from first-principles have been conducted using density functional theory (DFT) that probe the energetic landscape of potential gold nanoparticle shapes [10], including the effects of various surface ligands [11], which are vital for the synthesis of solution-phase noble metal nanoparticles [12]. However, such a technique does not take into account the intricacies of nucleation and growth competition in solution-based nanoparticle synthesis.…”