Hydrogen adsorption on Pt-coated B2-FeTi thin films: DFT study

P. JASEN, E. GONZÁLEZ, G. BRIZUELA, A. JUAN, J. MARCHETTI

Mar del Plata

Congreso; Cuarto Congreso Nacional – Tercer Congreso Iberoamericano de Hidrógeno y Fuentes Sustentables de Energía – HYFUSEN 2011; 2011

The intermetallic B2-FeTi is known as one of the promising material for reversible hydrogen storage.The capacity of FeTi for hydrogen storage is about 37% (in volume).FeTi has to store and release hydrogen at the atmospheric pressure and room temperature in comparison with other perspective hydrogen storage materials.However, this alloy requires an initial activation treatment.During activation treatment the surface is covered by an oxide layer, which hinders hydrogen absorption.The formation of surface oxide layer can beprevented by the usage of a thin layer of Pt as a cover.It is assumed that Pt coating or alloying will be beneficial for hydrogen uptake because Pt is an active material for hydrogen adsorption.We have modeled this intermetallic and computed the electronic structure in Pt-covered FeTi(110) surface using the VASP code with GGA approximation for the exchange-correlation potential.The electronic structure changes introduced by Pt andhydrogen in the surface layers of B2-FeTi are analyzed.We establish that the adsorption properties of cleanpure B2-FeTi surface are better when hydrogen can interact with both Fe and Ti atoms.This trend remains valid for Pt-covered FeTi and H adsorption is easier for Pt/FeTi system.The Fe states are shifted towards the Fermi level, which its highly reactivity in comparison with clean B2-TiFe.In the hollow position the H 1s energy level appears in the energy range much closer to the Fe valence band than that of Ti.The position of H level depends stronglyon the adsorbate sites. In the case of Ti-top position, the noticeable changes in electronic structure observedin the hydrogen-containing surfaces are connected primarily with formation of strongly hybridized H s-stateswith metal d-bonding states.