A significantly improved hydrogen storage performance of nanocrystalline Ti–Fe–Mn–Pr alloy

Abstract

Improving the activation performance and increasing the hydrogen storage capacity are the main problems faced by TiFe-based alloys. In this paper, alloys with chemical composition Ti1.1-xPrxFe0.8Mn0.2 (x = 0, 0.02, 0.04, 0.06, 0.08) are designed to achieve a reversible hydrogen storage capacity of 1.81 wt% in 15 min, which is close to the theoretical hydrogen storage capacity of TiFe alloy of 1.86 wt%. Alloys with Pr content x ≥ 0.04 can be directly activated without the incubation period. Transmission electron microscopy analysis found that doping Pr introduced TiFe (111) crystal plane with smaller surface energy, makes it easy for hydrogen atoms to diffuse from the surface to interior. Moreover, the addition of Pr significantly refines the grains and introduces a large number of grain boundaries and defects, improving the activation rate and kinetics. The physisorption results show that the specific surface area of the TiFe-based alloy after hydrogen absorption is significantly increased by doping Pr.