The tendency of V segregation in Pd/V(110) and Pd/V(100) surfaces induced by H adsorption

Abstract

This study employs density functional theory-based calculations to investigate the tendency of V atom segregation in Pd/V(100) and Pd/V(110) surfaces upon adsorption of H at varying coverage (0.25, 0.50, 0.75, and 1.0 ML). Geometric, energetic, and electronic structure analyses were performed to elucidate the stability of H on the surfaces, the V atoms segregation tendency, and the interactions of atoms in the systems. By calculating the relative energies, we found that Pd atoms will favor residing in the topmost layer of pristine Pd/V. Segregation of V atom in pristine Pd/V(100) is more endothermic than in Pd/V(110). For H-Pd/V systems, a tendency of V segregation was observed for 0.50–1.0 ML H coverage on Pd/V(110). V atom segregation was not predicted in H-Pd/V(100). Due to the more endothermic V atom segregation process in pristine (100) than in (110) facet, a larger energy is necessary to induce V segregation by H adsorption in (100). The adsorption energies, charge density difference distributions, and density of states revealed the stronger H-V interaction compared to H-Pd interaction. Hence, H adsorption stabilizes the V atoms in the topmost layers and could induce V segregation in the surface.