Decorating crystalline YFe2–xAlx on the Mg60La10Ni20Cu10 amorphous alloy as “hydrogen pump” to realize fast de/hydrogenation

Abstract

Mg-based amorphous alloys are one of the potential hydrogen storage materials but suffer from sluggish dehydrogenation/hydrogenation (de/hydrogenation) kinetics. In this work, as a new strategy, a hydrogen pump is built on the surface of amorphous alloys to solve this problem. By milling crystalline YFe2–xAlx hydrogen storage alloy with Mg60La10Ni20Cu10 amorphous alloy, fine crystalline particles were seeded on amorphous alloy powder to form a “strawberry” structure. According to the TEM observation, a metallurgical bonding boundary formed between the Mg-based amorphous matrix and the Y-Fe-Al crystalline alloy. By microstructure and de/hydrogenation kinetics investigation, the “hydrogen pump” effect of the seeded crystalline alloy was confirmed, which makes it much easier for the hydrogen to dissociate on and diffuse through the surface of the Mg-based amorphous alloy. With such effect, the H absorption rate of Mg60La10Ni20Cu10 amorphous alloy became almost eight times faster and it absorbs ∼2.8 wt.% in 1 h at 130 °C under 4.5 MPa-H2. Further, fast hydrogenation can even achieve at 70 °C and the low-temperature dehydrogenation kinetics of the amorphous hydride can be also greatly promoted. The present work proves that surface modification is of great importance for obtaining Mg-based amorphous alloy with ideal hydrogen storage performance.