Gold and Silver Clusters on TiO₂ and ZrO₂ (101) Surfaces: Role of Dispersion Forces

Abstract

The adsorption of Ag and Au atoms and Ag 4 and Au 4 clusters on the stoichiometric TiO 2 (anatase) and ZrO 2 (tetragonal) (101) surfaces has been investigated using DFT+U calculations with and without the inclusion of van der Waals (VdW) forces. We have considered the role of VdW interactions on the physical properties of the adsorbed species using three different approaches: two variants of the pair-wise force field method proposed by Grimme (DFT+D2 and DFT+D2'), and the vdW-DF method where the vdW contribution is expressed directly as a function of the electron density. The results show that already at the level of metal atoms and small clusters the inclusion of vdW interactions can change the order of stability of various isomers and, more important, can result in major corrections to the adsorption energies. These, in turn, can affect other properties as for instance the structure and chemical reactivity of supported metal particles on oxides or their diffusion properties.

Atomistic Models for Highly‐Dispersed PtSn/γ‐Al2O3 Catalysts: Ductility and Dilution Affect the Affinity for Hydrogen

“…Note that corrections for dispersion forces were not included in the present work for two reasons: i) for the sake of consistency with previous studies that we want to make comparison with, ii) and because such refinements to the PBE energies and forces were shown to be rather low in the case of PtSn surfaces in interaction with hydrogen . The situation might be more critical for the quantification of the interaction with hydrocarbons, which we do not consider here, or for the description of the metal‐support adhesion in some cases . Spin‐polarized calculations were performed for non‐supported clusters and used the interpolation formula of Vosko, Wilk and Nusair .…”

“…[36] The situation might be more critical for the quantification of the interaction with hydrocarbons, [27,36,48] which we do not consider here, or for the description of the metal-support adhesion in some cases. [49] Spinpolarized calculations were performed for non-supported clusters and used the interpolation formula of Vosko, Wilk and Nusair. [50] For isolated metallic clusters, order 1 Methfessel-Paxton smearing with σ = 0.1 eV was applied.…”

Tuning the charge state of Ag and Au atoms and clusters deposited on oxide surfaces by doping: a DFT study of the adsorption properties of nitrogen- and niobium-doped TiO2and ZrO2

“…63,64 Therefore, we used the semi-empirical dispersion correction as proposed by Grimme known as the DFT-D2 approach. However, these forces may be important for the description of the clustersupport interaction.…”

“…63,64 Therefore, we used the semi-empirical dispersion correction as proposed by Grimme known as the DFT-D2 approach. 64). For this reason we changed the parameters 6 C 6 and R 0 of the DFT-D2 approach, as suggested by Tosoni and Sauer.…”

Oxide‐Supported Gold Clusters and Nanoparticles in Catalysis: A Computational Chemistry Perspective

“…In general, the contribution of dispersion interactions to the gold/oxide interface binding is non‐negligible. Depending on the formalism used to include dispersion, the correction of the adsorption energies can go from a minimum of 20 % up to 100 % . However, the electronic structure of the supported clusters is not affected by the inclusion of dispersion forces …”