Interfacial Modulation for Anti-Disproportionation in Zr-Nb-Fe-Ni Based Hydrogen Isotope Storage Alloys Driven by...

Thermal/hydrogen-induced disproportionation is one of the most fatal obstacles for practical Zr₂Fe-based hydrogen isotope storage alloys. Here, an interfacial transport inhibition effect at the disproportionation interface is revealed, in which theoretical screening from a product-destabilization perspective identifies minor Nb substitution as an effective route to developing a disproportionation-resistant Zr_1.9Nb_0.1Fe_0.7Ni_0.3 alloy. This composition preserves an ultralow equilibrium hydrogen pressure and accelerated hydrogen absorption kinetics, while simultaneously delivering markedly enhanced resistance to disproportionation and outstanding cycling stability under harsh conditions. By integrating experimental results with thermodynamic and kinetic analyses, this work directs modification studies toward the viewpoint of interfacial transport kinetics for disproportionation. Combined density functional theory analyses and Ab initio molecular dynamics simulations systematically reveal that dispersed substitutional Nb atoms act as interfacial pinning centers at the hydride/disproportionation interfaces, effectively inhibiting detrimental interfacial phase transformation, closely related to weakened interfacial bonding strength, charge transfer, and orbital hybridization. Consequently, disproportionation-related atomic rearrangement as well as the nucleation and growth of ZrH₂ are kinetically retarded. For the first time, these findings demonstrated that targeted interfacial kinetic engineering constitutes an effective strategy for suppressing disproportionation in Zr₂Fe-based hydrogen storage systems.