Electrochemical Stability and Surface Segregation Tendencies of Core-Shell Structures. A Density Functional Theory Study

Density functional theory is used to calculate electrochemical stability and surface segregation tendencies of core-shell structures: with cores of Pd,Ir,Co,Pd₃Co and Pd₃Fe and Pt shells, in (111) and stepped surfaces both clean as well as under ¼ monolayer of atomic oxygen adsorbed. Several surfaces with perfect structures and also with defects as vacancies,dislocations, impurities and with various shell thicknesses are investigated. The study shows how the presence of atomic oxygen as adsorbate as well as defects in the surfaces affect dramatically the electrochemical stability and surface segregation. The results are consistent with previous experimental and theoretical studies.