Optimizing FeCoNiCrTi high‐entropy alloy with hydrogen pumping effect to boost de/hydrogenation performance of magnesium hydride

Abstract

Abstract The exploration of efficient, long‐lived and cost‐effective transition metal catalysts is highly desirable for the practical hydrogen storage of magnesium hydride (MgH 2 ) in sustainable energy devices. Herein, FeCoNiCrTi high‐entropy alloy (HEA) nanosheets were prepared via a facile wet chemical ball milling strategy and they were introduced into MgH 2 to boost the hydrogen storage performance. The refined HEA exhibited superior catalytic activity on MgH 2 . In contrast to additive‐free MgH 2 , the initial desorption temperature of the constructed MgH 2 ‐HEA composite was reduced from 330.0 to 198.5 °C and a remarkable 51% reduction in the dehydrogenation activation energy was achieved. Besides, the MgH 2 ‐HEA composite only required one‐twentieth time of that consumed by pure MgH 2 to absorb 5.0 wt% of H 2 at 225 °C. The synergy between the “hydrogen pumping” effect of Mg 2 Ni/Mg 2 NiH 4 and Mg 2 Co/Mg 2 CoH 5 couples, as well as the good dispersion of Fe, Cr and Ti on the surface of MgH 2 contributed to the enhanced de/hydrogenation performance of the MgH 2 ‐HEA composites. This study furnishes important steering for the design and fabrication of multiple transition metal catalysts and may push the commercial application of magnesium‐based hydrides one step forward.