The influence of pre-adsorbed Pt on hydrogen adsorption on B2 FeTi(111)

The hydrogen adsorption properties on a Pt covered Fe-terminated B2-FeTi (111) surface are studied using the Density Functional Theory (DFT). The calculations are employed to trace relevant orbital interactions and to discuss the geometric and electronic consequences of incorporating one Pt atom or a Pt monolayer on top of the FeTi surface. The most stable adsorption site is a distorted FCC hollow for one Pt atom and from this location we build the Pt monolayer (ML). The H-adsorption energy is very close among BRIDGE, HCP and FCC hollow sites (∼−0.45 eV) being lower for the TOP site (−0.34 eV) in the case of a Pt(111) fcc surface. In the case of a Pt ML/FeTi, the H more stabilized on a BRIDGE site (∼−1.13 eV) interacting with both a Pt and Fe atom. We also computed the density of states (DOS) and the overlap population density of states (OPDOS) in order to study the evolution of the chemical bonding after adsorption.