Theoretical Approach to the Sulfidation of the BaTiO₃(001) Surfaces and Its Effect on the H₂ Oxidation Reaction and CH₄ Sequential Dissociation

The performance of a solid oxide fuel cell based on BaTiO₃ anode improves when H₂ and CH₄ containing H₂S are employed as fuels. In this work, density functional theory calculations were conducted to reveal the origin behind this boost in performance. Our calculations predicted that the sulfidation of the BaTiO₃(001) surfaces is possible via different reaction pathways. For the hydrogen oxidation reaction, the presence of sulfur led to the formation of different molecular entities; thus alternative sequences of elementary steps for the reaction to proceed came to light, and no significant detrimental effect was noticed on the adsorption of the species involved. On the other hand, for the methane sequential dissociation, no detrimental effect on the methane activation and the promoted scission of some C-H bonds may be responsible for the mentioned boost in performance.