Bonding Properties of Isolated Metal Atoms on Two-Dimensional Oxides

Abstract

We report a systematic comparative dispersion-corrected DFT study of single (K, Au, and Pt) atom adsorption over a wide range of metal-supported oxide ultrathin films (MgO on Ag and Mo, ZnO on Cu, Ag, and Au, SiO 2 on Pt and Ru, TiO 2 on Ag and Pt, and ZrO 2 on Pt and ZrPt). These films include reducible and nonreducible oxides and have been prepared and characterized experimentally, showing very unusual and interesting behavior toward metal atom adsorption. The interaction of K and Au with the metal/oxide substrates is dominated by charge-transfer aspects, where K tends to assume positive charge and Au negative charge. This fact reflects into a general trend where metal-supported oxide films displaying a large work function (i.e., deep empty states) tend to bind K cations strongly, while supports with small work function (i.e., shallow donor states) strongly stabilize Au in anionic form. The correlation between adsorption energy and work function is not strong enough to neglect several other aspects related to chemical and morphological properties of the specific oxide/metal interface. The case of Pt is completely different: here, covalent contributions to the bonding prevail, and the bond strength depends on factors such as the surface morphology and local atomic coordination, rather than the support's work function.

A TbPc2 sub-monolayer deposit on a titanium dioxide ultrathin film: magnetic, morphological, and chemical insights

“…27,29 Indeed, studies on MgO multilayer films (up to 6ML) showing the increase of magnetic remanence of TbPc 2 also revealed the suppression of conduction electrons scattering from the metal to the molecule. 27 Additionally, we cannot exclude that the partially negative charge of the lepidocrocite-like ultrathin film 36,55 might also influence the electronic distribution of a TbPc 2 deposit, causing an alteration of the SMM magnetization dynamics from the bulk behaviour.…”

Quasi-Hexagonal to Lepidocrocite-like Transition in TiO2 Ultrathin Films on Cu(001)

“…The understanding of the TiO 2 growth as the ultrathin film (i.e., in the mono- and bilayer regime) on Cu(001) achieved in this study is of major importance for the development of new TiO 2 -based interfaces and devices. In light of a renewed interest in metal oxides as decoupling layers for atoms and molecules on metal surfaces, , we envision that the different bonding and charge transfer observed between the Cu substrate and the QH and LL TiO 2 phase could significantly influence the properties of the adsorbed species, leading to a deeper understanding of their interaction …”

“…In light of a renewed interest in metal oxides as decoupling layers for atoms and molecules on metal surfaces, 25,26 we envision that the different bonding and charge transfer observed between the Cu substrate and the QH and LL TiO 2 phase could significantly influence the properties of the adsorbed species, leading to a deeper understanding of their interaction. 27 ■ ASSOCIATED CONTENT * sı Supporting Information…”

“…On metals, TiO 2 thin films are commonly found as a stable lepidocrocite-like ( LL ) structure but other structures such as the quasi-hexagonal ( QH ) one were also reported. − The TiO 2 ultrathin film can be used to enhance the power conversion efficiency of the solar cell by reducing the electron–hole recombination on the ZnO surface . Furthermore, theoretical and experimental studies on the TiO 2 - LL structure were carried out, evidencing its potentialities on multiple fields, such as improved catalytic applications, , electrode materials, or as an alternative decoupling layer used to preserve the magnetic properties of atoms and molecules deposited on metals. − Controlling the fabrication of these ultrathin film oxide structures is crucial for their use in technological application, but a deep understanding of the growth processes is also required. Noticeably, the growth of the LL structure, which is the most stable TiO 2 film phase on different metal surfaces such as W(100), Ag(100), Pt(111), and Pt(110), critically depends on the deposition conditions. , In fact, on other metal surfaces such as Cu(001), only TiO 2 films with hexagonal structures were observed. , …”

The Journal of Physical Chemistry C Virtual Special Issue on Metal Clusters, Nanoparticles, and the Physical Chemistry of Catalysis

“…Advances in the theoretical methods and computational power create expectations for an increasing role of computations in the future, not only in interpreting existing experimental data but also in producing new predictions for the properties and mechanisms to be tested in experiments. In this VSI, methods based on the density functional theory (either its ground-state or real-time formalism) are used to study the role of optical excitations in the chemistry of clusters − and model nanowires, the effects of clusters’ detailed atomistic structures on the bonding properties of reactants and the catalytic activity, − and the bonding properties of single metal atoms on metal-supported thin-film oxides . Finally, the central concepts affecting the interpretation of kinetic data on catalytic reactionspossible non-Arrhenius behavior due to cluster fluxionality and the sensitivity of kinetic Monte Carlo simulations to linear scaling relations are discussed.…”