Micro-alloying design-enabled surface activity engineering for enhanced anti-poisoning properties of ZrCo-based hydrogen isotope storage materials

ZrCo alloy holds great promise for hydrogen isotope storage, yet its susceptibility to poisoning by impurity gases, especially CO, poses a challenge. This susceptibility arises due to the electron acceptor nature of the surface Co element and the formation of the d - π feedback bond, thereby impeding the surface hydrogen dissociation. Accordingly, we propose a novel local activity modulation strategy, where substituent elements are sacrificed to protect the active Co sites for hydrogen dissociation. Considering CO absorption capacity, solid solubility, and hydrogen affinity, we selected V, Cr, and Mn as micro-alloying elements and successfully prepared the single-phase ZrCo 0.97 (VCrMn) 0.03 alloy. Compared to pristine ZrCo, ZrCo 0.97 (VCrMn) 0.03 demonstrates significantly enhanced poisoning resistance. Notably, the hydrogenation kinetics of ZrCo 0.97 (VCrMn) 0.03 is 2.4 times higher than that of ZrCo in 4 bar H 2 + 5000 ppm CO. Interestingly, the controllable in situ formation of the Co 2 C phase shell structure during cycling further safeguards the surface reactivity of ZrCo 0.97 (VCrMn) 0.03 . Consequently, its capacity retention ratio after 25 cycles has been improved to 74.5% from 55.3% of the ZrCo alloy. These findings suggest that micro-alloying engineering could be a promising strategy for surface activity modulation to enhance the anti-poisoning properties of hydrogen storage materials.