The hydrogenation of MgB2 is a critical step in the reversibility of several well-known hydrogen storage reactions. Of the many processes that must occur during rehydrogenation, at least two of them take place near the surface: the dissociation of H2 molecules and the subsequent diffusion of atomic hydrogen. Using first-principles calculations, we determine the energetic barriers for these processes on the ideal Mg-terminated MgB2 (0001) surface, as well as on surfaces containing transition metal dopants (Sc-Zn, Y-Cd, Pt, and Au). The calculated dissociation barrier for H2 on the clean surface is 0.89 eV, and the surface diffusion barrier is 0.17 eV. However, we find examples of dopants that significantly decrease the activation barrier for the dissociation of H2. Our calculations suggest that Ni, Cu, and Pd are good catalytic candidates for the surface processes involved in MgB2 rehydrogenation.
|Original language||English (US)|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Apr 27 2015|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics