Hydrogen storage in nanocrystalline high entropy material

Abstract: In this study, a single-phase nanocrystalline Al-Cu-Fe-Ni-Cr high-entropy alloy (HEA) has been synthesized by mechanical alloying and comprehensively investigated for hydrogen storage responses evaluated in details. High-energy attritor ball mill was used to synthesize the alloy from elemental powder, and hexane medium was used as a process control agent. As synthesized materials was nanocrystalline in nature after 40 h of milling with a lattice parameter of 0.289 nm body-centered cubic (BCC) phase. As synthesized nanocrystalline Al-Cu-Fe-Ni-Cr HEA demonstrated remarkable hydrogen storage properties, absorbing 2.1 wt.% of hydrogen in 3 minutes at 300{\deg}C with 50 atm of hydrogen pressure. At the same temperature, it also desorbed about 1.6 wt.% of hydrogen in 6 minutes. These quick rates of absorption and desorption demonstrate how well the alloy absorbs and releases hydrogen. Additionally, the alloy showed outstanding cyclic stability, retaining almost all of its hydrogen capacity across 25 cycles with only a slight 0.2 wt.% loss. The nanocrystalline Al-Cu-Fe-Ni-Cr HEA is a potential option for hydrogen storage applications due to its outstanding cycle stability and fast kinetics of hydrogen storage and release.