Surface-hydrogenation activity regulation toward robust anti-poisoning of ZrCo-based hydrogen isotope storage materials

Abstract

ZrCo alloy is promising for hydrogen isotope storage but suffers severe CO poisoning due to d-orbital back-donation into CO π* orbitals, leading to strong chemisorption that blocks subsequent hydrogen dissociation. To address this, we conceptualize a surface-hydrogenation activity factor (η ⃗) as a descriptor for screening doping elements. This factor integrates key surface chemical parameters, including local lattice distortion, CO adsorption behavior, and the hydrogen dissociation energy barrier. Guided by η ⃗, we designed and synthesized a single-phase ZrCo0.97V0.03 alloy. Compared with pristine ZrCo, it exhibits a threefold enhancement in hydrogenation kinetics in a H2 + CO mixed-gas atmosphere. Mechanistically, V-induced localized tensile strain elevates surface potential and modulates charge transfer, lowering the H2 dissociation barrier in the presence of CO. Consequently, the ZrCo0.97V0.03 alloy maintains superior hydrogenation kinetics and cycling stability (80.1% retention) after 25 cycles in mixed gas, validating the η-based design strategy. This work establishes a surface-chemistry-guided approach linking dopant-induced structural modulation to poisoning-tolerant hydrogen storage performance.