Density functional theory studies of electronic properties of PdAg/Pd surface alloys

• Both the morphology and composition of PdAg surfaces are considered in this study. • The d-electron activities of Pd atoms are compared among these three surfaces. • The close-packed surface alloy is not better than less-densely packed surfaces. • The (100) surface activity remains well when the surface Ag concentration grows. The structural and electronic properties of Pd x Ag 1− x /Pd surface alloys were studied using periodic density functional theory calculations to unravel and understand the contributions of Ag concentration to the geometric and electronic properties on three low Miller index surfaces. The results indicate that both outward relaxation and the formation energy of surfaces increase significantly with increasing Ag concentration. Combining the density of states with d-band width and d-band center, it is clear that the electric activity of Pd atoms on the surfaces is enhanced by Ag atoms and increased in the order (1 0 0) > (1 1 1) > (1 1 0).