Speaker
Description
Hydrogen storage remains a challenge in the hydrogen economy due to its light weight and density. Metal alloys, particularly titanium-iron (TiFe), have emerged as a viable option for hydrogen storage at ambient conditions. TiFe is known for its ability to reversibly store hydrogen at room temperatures, with comparable volumetric capacities as that of liquid H2 (~100 kgH2 m-3)1. However, its relatively low gravimetric capacity and oxide formation present drawbacks for TiFe as a standalone storage material. To overcome these challenges, researchers have proposed elemental doping and post mechanical processing. Theoretical studies have suggested that incorporating transition elements (for ex: Cr, V, Nb, Mn) as dopants in TiFe can enhance its hydrogen storage properties2. By replacing Fe and Ti in the lattice, these dopants induce changes in lattice size and strain, creating favorable diffusion pathways for H2. To our best knowledge, there are limited research on TiFe doped with transition elements Ta, Nb3,4, and a clear correlation between its crystallographic structure and hydrogen storage properties is still lacking.
In this study, TiFe samples with transition elements V, Nb and Ta with varying stoichiometries were synthesized using vacuum arc melting (VAM). Characterization techniques including powder X-ray diffraction (XRD) and Extended X-Ray Absorption Fine Structures (EXAFS) analysis were employed. The results demonstrated high correlation between structural refinement achieved through PXRD and EXAFS analysis. H2 absorption and pressure-composition-temperature (PCT) measurements were conducted, which showed that precise doping of TiFe with transition element dopants significantly improved activation and kinetics. These findings contribute to a better understanding of dopants occupancy in the crystallographic structure of TiFe and its impact on hydrogen storage properties.
