Modification of the adsorption properties of O and OH on Pt–Ni bimetallic surfaces by subsurface alloying

We use periodic density functional theory to investigate the adsorption properties of O and OH on different Pt–Ni alloy systems, including Pt(1 1 1), Pt(1 1 1) with surface Ni (surface for short), PtNi3(1 1 1), PtNi(1 1 1), Pt3Ni(1 1 1), Pt(1 1 1)-skin-Pt3Ni, Pt(1 1 1) with subsurface Ni (subsurface for short), and Ni(1 1 1). It is found that the adsorption strength of both O and OH displays the order of subsurface < Pt(1 1 1)-skin-Pt3Ni < Pt(1 1 1) < Pt3Ni(1 1 1) < PtNi(1 1 1) < PtNi3(1 1 1) < Ni(1 1 1) < surface. It is shown that the subsurface alloy by the formation of a Ni monolayer in the subsurface of Pt(1 1 1) can change the position of d-band center with a downshift and result in a reduced adsorption strength of O and OH. Our results suggest that the Pt surface atoms of the Pt(1 1 1)-skin-Pt3Ni and subsurface alloys are more stable compared to Pt(1 1 1) surface in vacuum, but oxygen adsorption may destabilize the surface Pt atoms of the Pt(1 1 1)-skin-Pt3Ni and subsurface alloys and pure Pt surfaces.

► Systematic and comparative study of the adsorption properties of O and OH on different Pt–Ni alloy systems.
► The subsurface alloy exhibits the weakest O and OH adsorption strength among different Pt–Ni alloys.
► Oxygen adsorption may destabilize the Pt-based alloys and pure Pt surfaces.