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

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.