Solid–State Hydrogen Storage Materials with Excellent Selective Hydrogen Adsorption in the Presence of Alkanes, Oxygen, and Carbon Dioxide by Atomic Layer Amorphous Al2O3 Encapsulation

Metal hydrides with high hydrogen density provide promising hydrogen storage paths for hydrogen transportation. However, the requirement of highly pure H₂ for re-hydrogenation limits its wide application. Here, amorphous Al₂O₃ shells (10 nm) were deposited on the surface of highly active hydrogen storage material particles (MgH₂-ZrTi) by atomic layer deposition to obtain MgH₂-ZrTi@Al₂O₃, which have been demonstrated to be air stable with selective adsorption of H₂ under a hydrogen atmosphere with different impurities (CH₄, O₂, N₂, and CO₂). About 4.79 wt% H₂ was adsorbed by MgH₂-ZrTi@10nmAl₂O₃ at 75 °C under 10%CH₄ + 90%H₂ atmosphere within 3 h with no kinetic or density decay after 5 cycles (~ 100% capacity retention). Furthermore, about 4 wt% of H₂ was absorbed by MgH₂-ZrTi@10nmAl₂O₃ under 0.1%O₂ + 0.4%N₂ + 99.5%H₂ and 0.1%CO₂ + 0.4%N₂ + 99.5%H₂ atmospheres at 100 °C within 0.5 h, respectively, demonstrating the selective hydrogen absorption of MgH₂-ZrTi@10nmAl₂O₃ in both oxygen-containing and carbon dioxide-containing atmospheres hydrogen atmosphere. The absorption and desorption curves of MgH₂-ZrTi@10nmAl₂O₃ with and without absorption in pure hydrogen and then in 21%O₂ + 79%N₂ for 1 h were found to overlap, further confirming the successful shielding effect of Al₂O₃ shells against O₂ and N₂. The MgH₂-ZrTi@10nmAl₂O₃ has been demonstrated to be air stable and have excellent selective hydrogen absorption performance under the atmosphere with CH₄, O₂, N₂, and CO₂.