Small gold species at hydroxylated alumina surfaces. A computational study using embedded-cluster models of α-Al_2O_3(0001)

摘要

We calculated equilibrium structures for adsorption complexes of gold monomers, dimers, and trimers on a α-Al_2O_3(0001) model surface, partially covered by μ_1 and μ_3 hydroxyl groups. We applied a scalar-relativistic gradient-corrected density functional method to cluster models of the support that were embedded in an elastic polarizable environment. The most stable structures, with calculated adsorption energies in the range 0.81-1.74 eV, feature coordination bonds to surface μ_1-OH group and are 0.24-0.79 eV more stable than the corresponding Au_n complexes on a dehydrated surface. Isomeric rearrangements of the most stable complexes are hindered by barriers of 0.65-1.08 eV.