Enhanced Poisoning Resistance of TiFe-Based Hydrogen Storage Alloys via CeO ₂ Nanocoating in Impure Hydrogen Atmospheres

Hydrogen, which is a clean energy carrier, requires efficient storage for large-scale application. Although TiFe-based hydrogen storage alloys possess outstanding storage capabilities, they are susceptible to impurity gas poisoning (CO, CO₂, CH₄, O₂) during practical use, leading to performance decay. In this work, a TiFe_0.9 alloy coated with 10 wt % CeO₂ was synthesized via high-energy ball milling. Through material characterizations and systematic hydrogen storage performance tests, it was revealed that the uniform CeO₂ nanolayer coating introduces a substantial amount of oxygen vacancies derived from Ce³⁺. These vacancies serve as preferential reaction sites for impurity gases as well as form oxides at the interface, effectively inhibiting further Ti oxidation and preserving active hydrogen adsorption sites. Remarkably, in hydrogen containing 0.1% O₂, the TiFe_0.9-CeO₂ composite material exhibits a capacity retention rate of 27%, compared to the ball-milled alloy which suffered a complete loss after 20 cycles. This work presents a low-cost and simple approach for developing durable TiFe-based hydrogen storage materials with an enhanced tolerance to impurity-induced poisoning, supporting their practical application in hydrogen energy systems.