First-principles study of Pd-alloyed Cu(111) surface in hydrogen atmosphere at realistic temperatures

摘要

Alloying is a well-established and versatile method to modify and tune properties of functional materials. Alloy properties depend crucially on the spatial distribution of the alloying elements. In particular, in heterogeneous catalysis, the distribution of guest metal atoms at the catalytic surface has a dramatic effect on its chemical properties. Combining a cluster-expansion model, parameterized with density-functional theory calculations, with Monte Carlo sampling, we describe the distribution and segregation of Pd atoms on the Pd-alloyed Cu(111) surface as a function of H coverage at realistic temperatures. We find that, while in vacuum Pd enriches the near-surface region of Pd/Cu(111), Pd segregates to the bulk layers away from the surface under increasing H coverage. These findings are crucial for designing metal-alloy catalysts with dynamically changing properties.