Experimental and Theoretical Studies on Oxidation of Cu-Au Alloy Surfaces: Effect of Bulk Au Concentration

Abstract

We report results of our experimental and theoretical studies on the oxidation of Cu-Au alloy surfaces, viz., Cu 3 Au(111), CuAu(111), and Au 3 Cu(111), using hyperthermal O 2 molecular beam (HOMB). We observed strong Au segregation to the top layer of the corresponding clean (111) surfaces. This forms a protective layer that hinders further oxidation into the bulk. The higher the concentration of Au in the protective layer formed, the higher the protective efficacy. As a result, of the three Cu-Au surfaces studied, Au 3 Cu(111) is the most stable against dissociative adsorption of O 2, even with HOMB. We also found that this protective property breaks down for oxidations occurring at temperatures above 300 K.