First-Principles Study of O2 Dissociative Adsorption on Cu-, Pt-, and Pd-Doped Ag(111) Surfaces

The dissociative adsorption of O2 strongly depends on the activity of CO oxidation electrocatalysts. Using first-principles calculations, we investigated O2 dissociative adsorption on Cu-, Pt-, and Pd-doped Ag(111) surfaces. Our results show that the adsorption configuration designated t-b-t1 is the most energetically favorable adsorption state, with the O2 binding strength following the order AgCu(111) > AgPt(111) > AgPd(111) > Ag(111). By analyzing the factors that influence the d-band center, we infer that the ligand effect constitutes the dominant determinant of adsorption behaviour. For the subsequent dissociation of O2, our calculations identify a viable reaction pathway that begins with the t-b-t1 configuration and evolves into two oxygen adatoms adsorbed at adjacent hollow fcc sites. The computed energy barriers for this pathway follow the order Ag(111) > AgPt(111) > AgPd(111) > AgCu(111). These theoretical findings provide crucial guidance for the practical implementation of Ag-based bimetallic alloys as efficient CO oxidation electrocatalysts.