First-Principles Study of Alkoxides Adsorbed on Au(111) and Au(110) Surfaces: Assessing the Roles of Noncovalent Interactions and Molecular Structures in Catalysis

Microscopic understanding of molecular adsorption
on catalytic surfaces is crucial for controlling the
activity and selectivity of chemical reactions. However, for
complex molecules, the adsorption process is very systemspecific
and there is a clear need to elaborate systematic
understanding of important factors that determine catalytic
functionality. Here, we investigate the binding of eight
molecules, including seven alkoxides and one carboxylate, on
the Au(111) and Au(110) surfaces. Our density-functional
theory calculations including long-range van der Waals
interactions demonstrate the significant role of these “weak”
noncovalent forces on the adsorption structures, energetics,
and relative adsorbate stabilities. Interestingly, the binding energy trends are insensitive to the surface structure. Instead, the
adsorption stability depends strongly on the structural and chemical characteristics of the molecules: linear vs branching
configurations, number of unsaturated C−C bonds, bidentate adsorption, and the presence of electronegative atoms. Our
calculations help establish the influence of individual and collective chemical factors that determine the catalytic selectivity of
alkoxides.