Hydrogen Dissociation and Diffusion on Transition Metal=Ti,Zr,V,Fe,Ru,Co,Rh,Ni,Pd,Cu,Ag-doped Mg0001 Surfaces - Condensed Matter > Materials ScienceReport as inadecuate




Hydrogen Dissociation and Diffusion on Transition Metal=Ti,Zr,V,Fe,Ru,Co,Rh,Ni,Pd,Cu,Ag-doped Mg0001 Surfaces - Condensed Matter > Materials Science - Download this document for free, or read online. Document in PDF available to download.

Abstract: The kinetics of hydrogen absorption by magnesium bulk is affected by two mainactivated processes: the dissociation of the H$ 2$ molecule and the diffusionof atomic H into the bulk. In order to have fast absorption kinetics bothactivated processed need to have a low barrier. Here we report a systematicab-initio density functional theory investigation of H$ 2$ dissociation andsubsequent atomic H diffusion on TM=Ti,V,Zr,Fe,Ru,Co,Rh,Ni,Pd,Cu,Ag-dopedMg0001 surfaces. The calculations show that doping the surface with TM-s onthe left of the periodic table eliminates the barrier for the dissociation ofthe molecule, but the H atoms bind very strongly to the TM, therefore hinderingdiffusion. Conversely, TM-s on the right of the periodic table don-t bind H,however, they do not reduce the barrier to dissociate H$ 2$ significantly. Ourresults show that Fe, Ni and Rh, and to some extent Co and Pd, are allexceptions, combining low activation barriers for both processes, with Ni beingthe best possible choice.



Author: Monica Pozzo, Dario Alfe`

Source: https://arxiv.org/



DOWNLOAD PDF




Related documents