Hydrogen Desorption from Ti-Doped MgH2(110) Surfaces: Catalytic Effect on Reaction Pathways and Kinetic Barriers

TitleHydrogen Desorption from Ti-Doped MgH2(110) Surfaces: Catalytic Effect on Reaction Pathways and Kinetic Barriers
Publication TypeJournal Article
Year of Publication2012
AuthorsWang LL, Johnson DD
Journal TitleJournal of Physical Chemistry C
Volume116
Pages7874-7878
Date Published04
Type of ArticleArticle
ISBN Number1932-7447
Accession NumberWOS:000302591300033
Keywordsab-initio, alloys, ELECTRON-GAS, magnesium hydride, metals, mgh2, sorption kinetics, storage reactions, total-energy calculations, wave basis-set
Abstract

Transition-metal (TM) catalytic dopants are widely used in hydrogen-storage materials to increase hydrogen (H-2) desorption and absorption kinetics. Using density functional theory calculations, we elucidate the catalytic effect of Ti substitutional dopant on H-2 desorption from MgH2(110) surfaces. Kinetic energy barriers of H-2 desorption pathways are calculated via a nudged-elastic-band method. For a Ti-doped surface, we identify a concerted mechanism involving H bulk (vacancy-mediated) diffusion to feed H-2 surface desorption, arising from a synchronized diffusion of H atoms around Ti. The kinetic barrier for the Ti-doped surface is reduced by 0.41 eV-a 22% drop. We also show that the catalyzed H-2 desorption is mediated by a change in hydrogen coordination number of Ti, altering the associated Ti spin state.

URL<Go to ISI>://WOS:000302591300033
DOI10.1021/jp300794x
Alternate JournalJ. Phys. Chem. C