Structural, electronic, magnetic and chemical properties of B-, C- and N-doped MgO(001) surfaces

Abstract

Doping of simple oxide materials can give rise to new exciting physical and chemical properties and open new perspectives for a variety of possible applications. Here we use density functional theory calculations to investigate the B-, C- and N-doped MgO(001) surfaces. We have found that the investigated dopants induce magnetization of the system amounting to 3, 2 and 1 μB for B, C and N, respectively. The dopants are found to be in the X(2-) state and tend to segregate to the surface. These impurity sites also present the centers of altered chemical reactivity. We probe the chemisorption properties of the doped MgO(001) surfaces with the CO molecule and atomic O. The adsorption of CO is much stronger on B- and C-doped MgO(001) compared to pure MgO(001) as the impurity sites serve as potent electron donors. The situation is similar to the case of atomic oxygen, for which we find the adsorption energy of -8.78 eV on B-doped MgO(001). The surface reactivity changes locally around the dopant atom, which is mainly restricted to its first coordination shell. The presented results suggest doped MgO as a versatile multifunctional material with possible use as an adsorbent or a catalyst.

Tuning the electronic and chemisorption properties of hexagonal MgO nanotubes by doping – Theoretical study

“…For all the considered dopants and the nanotube sizes (from (MgO) 6 to (MgO) 15 ) we found that dopants preferred the edge sites of the nanotube. This is in agreement with the results reported for the C-doped multiwall MgO nanotubes [20], and the MgO(001) terraces doped with B, C and N [21].…”

“…It is the most apparent for B, and the effect decreases towards N, as discussed in Ref. [21]. For F and Li, having 2s 2 np 5 [19].…”

“…In this study, we extend our previous work on non-metal doped MgO(001) [21] for the case of hexagonal MgO nanotubes and investigate how doping with Li, B, C, N, and F can tune their properties. Due to their atomic sizes these dopants are considered as suitable ones for MgO, bulk, surface or nanostructures, in particular, nanotubes addressed here.…”

“…As discussed above, the introduction of dopants into the structure of a MgO leads to the appearance of unpaired electrons, either at the dopant atoms (doping with B, C, and N) or surrounding O and Mg atoms (doping with Li and F). As suggested earlier [21], such sites can be considered as the confined radical species, the centers of altered chemical reactivity. This might open a number of possibilities for employing such doped oxide materials, for example, as adsorbents or heterogeneous catalysts.…”

“…The states induced by dopants also alter the band gap of MgO nanotubes. These states are typically located in the band gap, like in the case of doped MgO(001) surface [21] that results in gap narrowing. In fact, Li and F doping present two extreme cases.…”