Gold nanostructures on iron oxide surfaces and their interaction with CO.

We review results of density functional theory calculations of the adsorption of single gold atoms and formation of sub-nanometer Austructures (= 2 to 5) on most stable iron oxide surfaces: hematite (0001), and magnetite (111) and (001). Structural, energetic, and electronic properties of Austructures on both Fe- and O-rich oxide terminations are discussed. Different chemical character of the two oxide terminations is reflected in distinctly stronger binding of gold at the oxygen- than at the iron-terminated surface, and in different changes of the adsorption binding energy with the size of the Aucluster.

On the Structure of Ultrathin FeO Films on Ag(111).

Ultrathin transition metal oxide films exhibit unique physical and chemical properties not observed for the corresponding bulk oxides. These properties, originating mainly from the limited thickness and the interaction with the support, make those films similar to other supported 2D materials with bulk counterparts, such as transition metal dichalcogenides. Ultrathin iron oxide (FeO) films, for example, were shown to exhibit unique electronic, catalytic and magnetic properties that depend on the type of the used support.

Adsorption of gold subnano-structures on a magnetite(111) surface and their interaction with CO.

Gold deposited on iron oxide surfaces can catalyze the oxidation of carbon monoxide. The adsorption of gold subnano-structures on the Fe-rich termination of the magnetite(111) surface has been investigated using density functional theory. The structural, energetic, and electronic properties of gold/magnetite systems have been examined for vertical and flattened configurations of adsorbed Aun (n = 1-4) species.

CO adsorption on small Aun (n = 1-4) structures supported on hematite. II. Adsorption on the O-rich termination of α-Fe2O3(0001) surface.

The adsorption of small Aun (n = 1-4) nanostructures on oxygen terminated α-Fe2O3(0001) surface was investigated using density functional theory in the generalized gradient approximation of Perdew-Burke-Ernzerhof (PBE) form with Hubbard correction U, accounting for strong electron correlations (PBE+U). The structural, energetic, and electronic properties were examined for two classes of the adsorbed Aun nanostructures with vertical and flattened configurations. Similarly to the Fe-terminated α-Fe2O3(0001) surface considered in Part I, the flattened configurations were found energetically more favored than vertical ones.

CO adsorption on small Aun (n = 1-4) structures supported on hematite. I. Adsorption on iron terminated α-Fe2O3 (0001) surface.

This is the first of two papers dealing with the adsorption of Au and formation of Aun nanostructures (n = 1-4) on hematite (0001) surface and adsorption of CO thereon. The stoichiometric Fe-terminated (0001) surface of hematite was investigated using density functional theory in the generalized gradient approximation of Perdew-Burke-Ernzerhof (PBE) form with Hubbard correction U, accounting for strong electron correlations (PBE+U). The structural, energetic, and electronic properties of the systems studied were examined for vertical and flattened configurations of Aun nanostructures adsorbed on the hematite surfaces.

Fe adsorption on hematite (α-Fe2O3) (0001) and magnetite (Fe3O4) (111) surfaces.

The structure and electronic properties of different terminations of hematite (0001) and magnetite (111) surfaces upon submonolayer Fe adsorption were studied using the spin-polarized density functional theory (DFT) including the Hubbard correction term U (DFT+U). On both oxides the Fe atoms were adsorbed on the most stable iron and oxygen terminated surfaces. The results show that Fe atoms bind strongly both to hematite and magnetite surfaces, however, the binding is distinctly stronger at the oxygen than at the iron terminated surfaces.

Surface properties of clean and Au or Pd covered hematite (α-Fe(2)O(3)) (0001).

The structure and electronic properties of different terminations of the α-Fe(2)O(3)(0001) surface were studied with spin-polarized density functional theory (DFT) and the DFT + U method accounting for the effect of strong on-site Coulomb correlations. The results for lattice relaxation, electronic and magnetic properties are presented and discussed. Though the DFT and DFT + U methods provide qualitatively very similar surface geometries they differ very much in the prediction of the electronic and magnetic properties, and the surface energetics of the clean α-Fe(2)O(3)(0001).