Underpotential deposition of hydrogen on Pt(111): a combined direct molecular dynamics/density functional theory study

Abstract

A combined direct molecular dynamics/density functional theoretical study of the electro-oxidation of molecular hydrogen at the Pt(111)/water interface has been carried out to provide insights into the adsorbed underpotential deposition (UPD) states of hydrogen at submonolayer coverages of bridging hydrogen atoms Hads(bridge). As in our previous study, H2 oxidation proceeds via the Heyrovsky process, forming a hydrated H+ ion and an UPD hydrogen atom, which is strongly adsorbed and is lying nearly flat in a bridging position on the Pt(111) surface. At submonolayer coverage, the UPD Hads(bridge) atoms spontaneously self-assemble to form a hexagonal 2D honeycomb network on the Pt(111) surface, a signature that could be considered to be characteristic of UPD states of hydrogen.