The rare earth doped Mg₂Ni (0 1 0) surface enhances hydrogen storage

Rare earth doping has been proved to be an effective method to improve hydrogen storage properties of Mg-based alloys. In this work, the effect of rare earth (Y, Ce, La, Sc) doping on the thermal stability, electronic property and hydrogen adsorption/desorption behavior of Mg₂Ni (0 1 0) surface are systematically investigated by first principles calculation. The results show that rare earth doping in Mg₂Ni (0 1 0) surface are thermodynamic feasible. The calculated electronic structures shown that rare earth atoms weaken the binding strength between H and Mg₂Ni (0 1 0) substrate, thus reduce the hydrogen diffusion and desorption energies barriers, and improve the hydrogen storage properties of Mg₂Ni. Among the four rare earth elements, Ce shows the best potential. Notably, the substitution doping of Ce to Mg atom significantly reduces the H diffusion barrier by 0.32 eV and H₂ desorption barrier by 1.0 eV. This discovery provides a direction for the preparation of rare earth doped Mg₂Ni hydrogen storage materials.