Ab initio density functional study of MgO (001) surface with topological defects

Abstract

Magnesium oxide (MgO) is a useful material because of its catalyticalproperties. Moreover, surface defects have been found to play a crucial role in determining the activity and selectivity of catalytic surfaces. We present the results of a theoretical investigation of the electronic structure of the MgO (001) surface with three different topological defects. Our calculations are based on density functional theory (DFT) and the pseudopotential method. Slab geometry and periodic boundary conditions have been included with occupied orbitals expanded in plane waves. We compare the obtained results of the (001) MgO clean surface with those containing topological defects. The density of states DOS is analyzed in each case, as well as the chemical nature of the atoms belonging to the defects.

Theoretical Study on the Role of Surface Basicity and Lewis Acidity on the Etherification of Glycerol over Alkaline Earth Metal Oxides

“…It is also known that defects on the surface can change the activity due to a higher number of coordinatively unsaturated atoms. [22] Furthermore, interactions of MgO with water or methanol have already been calculated [23,24] and it was proven that local surface defects, like corners, kinks and steps, can significantly influence the adsorption of water. [23] Therefore, we have modeled a stepped surface of CaO represented by the Miller indices (501), as shown in Figure 6.…”

DFT Modeling of Reaction Mechanism and Ab Initio Microkinetics of Catalytic N2O Decomposition over Alkaline Earth Oxides: From Molecular Orbital Picture Account to Simulation of Transient and Stationary Rate Profiles

“…Surface corrugation is lower than 2% of the interionic distance, and the outermost atomic plane relaxes inward by 1% of the interlayer spacing in each case . The quite large difference in the stabilization energy of the (100) and other low-index terminations is reflected in the typical cubic shape of the AEO crystallites. , The (100) terraces are characterized furthermore by lowering of the coordination of the surface ions from six to five . Owing to their highly ionic nature, to a large extent the reactivity of the alkaline earth oxides is dictated by anisotropy of the surface Madelung energy ( E Mad ), which varies for different coordination of O 2– (surf) sites, depending on their topological locations and on the interionic distances d = r A 2+ + r O 2– .…”

“…24,25 The (100) terraces are characterized furthermore by lowering of the coordination of the surface ions from six to five. 26 Owing to their highly ionic nature, to a large extent the reactivity of the alkaline earth oxides is dictated by anisotropy of the surface Madelung energy (E Mad ), which varies for different coordination of O 2− (surf) sites, depending on their topological locations and on the interionic distances d = r A 2+ + r O 2− . Thus, the pronounced difference in basicity of the O 2− (surf) active sites originates from different lattice parameter (MgO: a = 4.21 Å; CaO: a = 4.81 Å; and SrO: a = 5.16 Å) 11 and is reflected in their activity toward CO 2 adsorption 27 and N 2 O decomposition.…”

First Row Transition Metal Atom Adsorption On-Top of F°s Defects of a MgO(100) Surface

“…Several studies have already addressed the characteristics of such a defect [27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42] as well as the interaction of some atoms with it. 3,[43][44][45][46][47][48][49][50][51][52][53][54] To our knowledge, this paper is the first one to address the adsorption of the whole first transition metal atoms series.…”

“…Several studies have already addressed the characteristics of such a defect − as well as the interaction of some atoms with it. ,− To our knowledge, this paper is the first one to address the adsorption of the whole first transition metal atoms series. It is also the direct continuation of our previous study about the adsorption of the same atom series on the perfect surface .…”