Adsorption Configurations of Carbon Monoxide on Gold Monolayer Supported by Graphene or Hexagonal Boron Nitride Film: A First-Principles Study

Using density functional theory with a semiempirical van der Waals approach proposed by Grimme, the adsorption behavior of carbon monoxide on a gold monolayer supported by graphene or monolayer hexagonal boron nitride has been investigated. Based on the changes in the Dirac cone of graphene and a Bader charge analysis, we observe that the Au(111) monolayer gains a small electron charge from graphene and monolayer $h$-BN. The adsorbed CO molecule adopts similar adsorption configurations on Au(111)/graphene and Au(111)/$h$-BN with Au-C distance 2.17$-$2.50 {\AA} and Au-C-O angle of $123.9^{\circ} - 139.6^{\circ}$. Moreover, we found that for low CO coverages, bonding to the gold surface is surprisingly energy-favorable. Yet the CO adsorption binding energy diminishes at high coverage due to the repulsive van der Waals interactions between CO molecules.