UCL logo

UCL Discovery

UCL home » Library Services » Electronic resources » UCL Discovery

Hydrogen dissociation and diffusion on Ni- and Ti-doped Mg(0001) surfaces

Pozzo, M; Alfe, D; Amieiro, A; French, S; Pratt, A; (2008) Hydrogen dissociation and diffusion on Ni- and Ti-doped Mg(0001) surfaces. J CHEM PHYS , 128 (9) , Article 094703. 10.1063/1.2835541.

Full text not available from this repository.

Abstract

It is well-known, both theoretically and experimentally, that alloying MgH2 with transition elements can significantly improve the thermodynamic and kinetic properties for H-2 desorption, as well as the H-2 intake by Mg bulk. Here, we present a density functional theory investigation of hydrogen dissociation and surface diffusion over a Ni-doped surface and compare the findings to previously investigated Ti-doped Mg(0001) and pure Mg(0001) surfaces. Our results show that the energy barrier for hydrogen dissociation on the pure Mg(0001) surface is high, while it is small/null when Ni/Ti are added to the surface as dopants. We find that the binding energy of the two H atoms near the dissociation site is high on Ti, effectively impeding diffusion away from the Ti site. By contrast, we find that on Ni, the energy barrier for diffusion is much reduced. Therefore, although both Ti and Ni promote H-2 dissociation, only Ni appears to be a good catalyst for Mg hydrogenation, allowing diffusion away from the catalytic sites. Experimental results corroborate these theoretical findings, i.e., faster hydrogenation of the Ni-doped Mg sample as opposed to the reference Mg- or Ti-doped Mg. (C) 2008 American Institute of Physics.

Type:Article
Title:Hydrogen dissociation and diffusion on Ni- and Ti-doped Mg(0001) surfaces
DOI:10.1063/1.2835541
Keywords:AUGMENTED-WAVE METHOD, MINIMUM ENERGY PATHS, ELASTIC BAND METHOD, METAL-SURFACES, STORAGE PROPERTIES, TRANSITION-METALS, SADDLE-POINTS, ADSORPTION, MAGNESIUM, MG
UCL classification:UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Earth Sciences

Archive Staff Only: edit this record