Ab initio investigation of O₂ adsorption on Ca-doped LaMnO₃ cathodes in solid oxide fuel cells

Abstract

We present a Hubbard-corrected density functional theory (DFT+U) study of the adsorption and reduction reactions of oxygen on the pure and 25% Ca-doped LaMnO3 (LCM25) {100} and {110} surfaces.

Surface oxygen Vacancies on Reduced Co3O4(100): Superoxide Formation and Ultra‐Low‐Temperature CO Oxidation

“…The computed charge transfers from the oxide to the adsorbed O 2 molecule are 0.1 and 0.22 electron charges for the most strongly bound O 2 molecules on a single (case 1) and a double vacancy (case 7), respectively, which is in the range of values computed by other authors for superoxide. [ 41 , 49 ] Figure S6 in the SI displays ball‐stick structural models for all cases in Table 2 . Projected densities of state before and after adsorption are shown in Figure S7.…”

Surface oxygen Vacancies on Reduced Co3O4(100): Superoxide Formation and Ultra‐Low‐Temperature CO Oxidation

“…Thec omputed charge transfers from the oxide to the adsorbed O 2 molecule are 0.1 and 0.22 electron charges for the most strongly bound O 2 molecules on asingle (case 1) and ad ouble vacancy (case 7), respectively,w hich is in the range of values computed by other authors for superoxide. [41,49] Figure S6 in the SI displays ball-stick structural models for all cases in Table 2. Projected densities of state before and after adsorption are shown in Figure S7.…”

Oxygen (O2) reduction reaction on Ba-doped LaMnO3 cathodes in solid oxide fuel cells: a density functional theory study

“…Similar to previous studies [10], all the surface calculations for the interactions between the molecular oxygen species on the LSM25 and LBM25 surfaces were performed by relaxing the top three layers while keeping the bottom five layers fixed at the bulk parameters. The adsorption energy was calculated according to the following relation:…”

“…For O 2 adsorption and subsequent reduction on pure and 25% Ca-doped LaMnO 3 (LCM25) {100} and {110} surfaces, Aniagyei et al, [10] reported that adsorption or reduction processes are more favorable at the Mn sites than La and Ca sites at the DFT level with Hubbard correction. The adsorption energies calculated for the {110} surfaces were more favorable and stable than the {100}.…”

“…In this work, an extension to previous studies [10], Hubbard-corrected DFT approach is applied to study the Gibbs free energies of adsorption of the multiple reaction paths associated with the reduction of oxygen at 25% Ba-doped LaMnO 3 {100} and {110} surfaces (LBM25). The oxygen reduction energetics on LBM25 surfaces are compared with LCM25 [10] and LSM25 [see Table S1 and Figure S1 and S2], the main cathode of preference for conventional SOFCs. This is to ascertain whether they could be used as an alternative electrocatalyst for oxygen reduction reaction (ORR) based on their adsorption/reduction energies.…”