Adsorption of Cu, Ag, and Au atoms on graphene including van der Waals interactions

TL;DR

This study systematically investigates how copper, silver, and gold atoms adsorb onto graphene, emphasizing the importance of van der Waals interactions and comparing different computational methods to understand binding preferences and structural distortions.

Contribution

It provides a detailed analysis of metal-graphene adsorption sites, including the effects of van der Waals interactions, and compares the results of vdW-DF and PBE+D2 methods.

Findings

Copper, silver, and gold atoms bind to graphene with van der Waals interactions.

Silver shows binding in vdW schemes but not in GGA.

Quantitative differences exist between vdW-DF and PBE+D2 results.

Abstract

We performed a systematic density functional study of the adsorption of copper, silver, and gold adatoms on graphene, especially accounting for van der Waals interactions by the vdW-DF and the PBE+D2 methods. In particular, we analyze the preferred adsorption site (among top, bridge, and hollow positions) together with the corresponding distortion of the graphene sheet and identify diffusion paths. Both vdW schemes show that the coinage metal atoms do bind to the graphene sheet and that in some cases the buckling of the graphene can be significant. The results for silver are at variance with those obtained with GGA, which gives no binding in this case. However, we observe some quantitative differences between the vdW-DF and the PBE+D2 methods. For instance the adsorption energies calculated with the PBE+D2 method are systematically higher than the ones obtained with vdW-DF. Moreover, the equilibrium distances computed with PBE+D2 are shorter than those calculated with the vdW-DF method.