First-principles investigation of Ag-Cu alloy surfaces in an oxidizing environment

摘要: In this paper, we investigate by means of first-principles density functional theory calculations the (111) surface Ag-Cu alloy under varying conditions pressure surrounding oxygen atmosphere and temperature. This has been recently proposed as a catalyst with improved selectivity for ethylene epoxidation respect to pure silver, commonly used in industrial applications. Here, show that presence leads copper segregation surface. Considering free energy function composition, construct convex hull stability various structures. By including dependence on chemical potential, are able compute phase diagram temperature, pressure, composition. We find that, at temperature typically epoxidation, number structures can be present alloy, clean Ag(111), thin layers oxide, thick oxidelike These results consistent with, help explain, recent experimental results.