Enhancing Room-Temperature Hydrogen Storage Properties in Ti–V–Cr–Nb–Mo/Fe Multielement Alloys via Substitutional Tuning

Building upon previously reported high-entropy alloys (HEA) in the Ti–V–Cr–Nb–Mo/Fe compositional space, this study presents a novel bcc alloy containing 6 at. % of the earth-abundant element Fe, exhibiting enhanced hydrogen storage properties at room temperature (25 °C). The optimized bcc Ti23V30Nb10Cr31Fe6 alloy rapidly absorbs hydrogen at room temperature with a maximum gravimetric capacity of 3.4 wt % and an enthalpy of hydride formation of −34 kJ/mol H2. This value is among the lowest reported to date for bcc HEAs. The reversible capacity of this alloy remains stable at 2.0 wt % upon 20 absorption/desorption cycles at room temperature, which is among the highest reported values for this material class. Collectively, these advances highlight the potential of Fe-containing multielement alloys as efficient and economical candidates for next-generation hydrogen storage systems.