Gustavo E. Ramirez-Caballero1, Yuguang Ma2, J. Rafael Callejas-Tovar2, and Perla B. Balbuena2. (1) Materials Science and Engineering Program, Texas A&M University, 3003 TAMU, Universidad Industrial de Santander, College Station, TX 77843, (2) Department of Chemical Engineering, Texas A&M University, 3122 TAMU, College Station, TX 77843
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.