Strain and doping effects on the energetics of hydrogen desorption from the MgH2 (001) surface
1 Condensed Matter Theory Group, Department of Physics and Astronomy, Uppsala University Box 516, S-75120 Uppsala, Sweden, EU
2 Applied Materials Physics, Department of Materials and Engineering, Royal Institute of Technology (KTH) S-10044 Stockholm, Sweden, EU
Received: 31 October 2012
Accepted: 5 January 2013
On the basis of first-principles calculations we have systematically investigated the energetics of hydrogen desorption from the MgH2 (001) surface. Based on total energy and electronic structure calculations, two modes namely strain and doping of selected dopants (Al, Si, Ti) and the combined effect of both on the dehydrogenation energies (ΔH) of MgH2 (001) systems have been analyzed. The maximum improvement in ΔH has been obtained with the combined effect of doping and strain. Among all the dopants, Al gives the lowest value of ΔH when the system Al-MgH2 is subjected to a 7.5% biaxial symmetric strain whereas the Si-MgH2 systems show the least improvement in ΔH. The doping of Ti on MgH2 (001) is also very beneficial even without strain. The reduction in ΔH is caused by the charge localization on the metal atoms, destabilization and the weakening of metal-hydrogen bonds.
PACS: 71.15.Nc – Total energy and cohesive energy calculations / 71.20.-b – Electron density of states and band structure of crystalline solids / 71.20.Be – Transition metals and alloys
© EPLA, 2013