First-principles study of dehydrogenation on group IV elements Si, Ge, or Sn doped MgH₂(110) surface

The dehydrogenation on group IV elements Si, Ge, or Sn doped MgH₂(110) surface was investigated by first-principles calculations. In addition, the dopant site preference was determined by comparing the total energies of different doping site systems. The results showed that Si and Ge prefer to occupy interstitial sites, while Sn prefers to replace one Mg atom. The electronic structure and density of states show that the doping of Si, Ge, or Sn significantly weakens the Mg-H bond on the surface of MgH₂(110), and the band gap of the system is reduced, leading to structural instability. Finally, the calculated results of dehydrogenation energy and activation energy barrier indicated that Ge best improves the thermodynamics and hydrogen desorption kinetics of the MgH₂(110) surface, followed by Si and Sn.