Hydrogen storage properties of MgTiVZrNb high-entropy alloy and its catalytic effect upon hydrogen storage in Mg

Abstract

Herein, a new approach relying on six parameters has been proposed to design the high-entropy alloy (HEA) with a single-phase BCC solid solution based on the Mg–Ti–V–Zr–Nb system. The Mg10Ti30V25Zr10Nb25 alloy was selected among 5152 calculated compositions. Subsequently, the HEA is prepared by mechanical alloying and introduced into the Mg to study the effect of HEA on the hydrogen storage performance of Mg/MgH2 system. Results show that the HEA exhibits excellent hydrogen absorption kinetics at room temperature, while the hydrogen absorption capacity is about 1.196 wt%. Moreover, the addition of HEA can significantly improve the hydrogen absorption and desorption kinetics of Mg at low temperatures. The dehydrogenation activation energy of the composites reduces from 121.94 ± 4.08 to 91.66 ± 1.31 kJ mol−1, and HEA exhibits good catalytic activity. The initial hydrogenation and dehydrogenation temperatures of Mg‒15 wt% HEA composite are about 418 K and 526 K, which are 78 K and 47 K lower than pure Mg, respectively. The Mg‒15 wt% HEA composite has good cycling stability.