Energy of Oxygen-Vacancy Formation on Oxide Surfaces: Role of the Spatial Distribution

Abstract

Oxygen vacancy formation energies are often used as a descriptor of the catalytic activity of metal oxides for oxidation reactions having the Mars-van Krevelen mechanism. When these energies are calculated, it is often assumed that they depend only on the concentration of the vacancies in the top oxygen layer. Previous work has shown that in the case of TiO2 and V2O5, the energy of vacancy formation depends not only on their concentration but also on the manner in which they are distributed on the surface. However the energy change due to the change of configuration in these systems is very small. Here we find that in the case of α-MoO3(010) the dependence on the energy of vacancy formation of the distribution of vacancies is very large: if the lattice made by the vacancies consists of parallelograms, the energy of vacancy formation is 0.4 eV smaller than when the lattice consists of rectangles (the two systems having the same vacancy concentration).

Heterogeneously Catalyzed Aerobic Oxidation of Sulfides with a BaRuO3 Nanoperovskite

“…The results are summarized in Table . It has been accepted that the energy for oxygen vacancy formation is a good descriptor of the oxidizing power of an oxide: a lower energy for vacancy formation indicates a better oxidant. , The vacancy formation energies of the Ru-based oxide materials were strongly dependent on the structure and type of constituent oxygen atoms and increased in the order of the face-sharing O A atom in BaRuO 3 (3.43 eV) < SrRuO 3 (3.59/3.66 eV) < CaRuO 3 (3.69/3.71 eV) < RuO 2 (4.03 eV) < the corner-sharing O B atom in BaRuO 3 (4.04 eV).…”

“…It has been accepted that the energy for oxygen vacancy formation is a good descriptor of the oxidizing power of an oxide: a lower energy for vacancy formation indicates a better oxidant. 71,72 The vacancy formation energies of the Rubased oxide materials were strongly dependent on the structure Figure 9b shows XPS O 1s spectra for the Ru-based oxides. The broad peaks can be deconvoluted into three distinct peaks around 529.0, 530.5, and 532.2 eV, which are attributed to lattice oxygen, adsorbed oxygen species, and adsorbed molecular water, respectively (Table S3).…”

Activity Tuning of Cobalt Ferrite Nanoparticles Anchored on N‐Doped Reduced Graphene Oxide as a Potential Oxygen Reduction Electrocatalyst by Zn Substitution in the Spinel Matrix

“…The change in the ORR activity from the Zn substitution value of 0.1 to 0.3 is a consequence of the interplay between the hole and ionic distribution in the B site ,. The generated oxygen vacancies subsequent to the displacement of the Fe 3+ ions with the Zn 2+ ions in the tetrahedral site can concomitantly affect the adsorption and desorption energy of the molecular oxygen . This type of activity enhancement caused by oxygen vacancies can be explained by Marsvan Kervelen mechanism .…”

“…The generated oxygen vacancies subsequent to the displacement of the Fe 3+ ions with the Zn 2+ ions in the tetrahedral site can concomitantly affect the adsorption and desorption energy of the molecular oxygen . This type of activity enhancement caused by oxygen vacancies can be explained by Marsvan Kervelen mechanism . As the mechanism says, the oxygen vacancies created in the crystal structure provides the active site for adsorption of molecular oxygen.…”

Oxygen Vacancy Formation on α-MoO3 Slabs and Ribbons

“…Previous computational work [56][57][58][59][60][61][62][63][64][65][66][67][68][69][70][71][72][73] on MoO3 was performed for the (010) surface. This is the cleavage plane and therefore is expected to have the lowest surface energy and be predominantly present in MoO3 crystallites.…”