Silicene: A Promising Surface to Achieve Morphological Transformation in Gold Clusters

In recent years, gold clusters supported on solid materials have attracted considerable attention because of their various potential applications. With the objective of stabilizing the energetically less stable but catalytically more active planar form of finite sized gold clusters on some suitable solid support, we have theoretically investigated the morphological transformation of gold dimer, trimer, and Au20 clusters on pristine silicene/Ag(111) surface. In contrast to previous schemes which have been suggested for the stabilization of planar structures by appropriate surfaces, the present proposal does not require any external influence such as doping or application of external electric field. In fact, we have exploited the special characteristics of the silicene surface, namely, buckled nature and weak Si–Si π bonding, which enable this surface to make strong Si–Au covalent bonds resulting in the two-dimensional planar Au20 isomer being more stable than its three-dimensional tetrahedral structure. In contrast to this, as already reported in the literature, the planar isomer of the Au20 cluster is not energetically favored when it is adsorbed on a pure graphene surface. Moreover, Bader charge density analysis indicates that the amount of charge transfer from the silicene surface to the planar Au20 cluster is considerably high, thereby increasing the possibility of enabling this composite system to act as a better catalyst. It would be interesting to investigate the adsorption of gold clusters on the silicene surface experimentally for the verification of our theoretical prediction.