TiVNb-based high entropy alloys as catalysts for enhanced hydrogen storage in nanostructured MgH2

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Vol. 11; no. 9; pp. 4789 - 4800
• Main Authors: Zhang, Jingxi, Huang, Liu, Zhou, Chengshang, Sun, Pei, Guo, Xueyi, Zhigang Zak Fang
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 27.02.2023
• Subjects: Alloys; Catalysts; Dehydrogenation; High entropy alloys; Hydrides; Hydrogen; Hydrogen storage; Hydrogenation; Kinetics; Magnesium; Reaction kinetics; Room temperature
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/d2ta08086a

Magnesium hydride (MgH2) is a promising candidate for hydrogen storage, but suffers from its sluggish de/hydrogenation kinetics. Catalytic addition is considered one of the most effective methods to improve the kinetics of Mg-based hydrides. Herein, the equiatomic high entropy alloys (HEAs), namely, TiVNbZrFe, TiVNbZrNi, and TiVNbCrNi, are used as catalysts for MgH2. The results show that HEAs exhibit the C14 Laves structure and provide excellent catalytic impact. Among these HEA catalysts, the TiVNbZrFe alloy shows a superior catalytic effect in improving the de/hydrogenation kinetics and cycling properties of MgH2. In particular, MgH2–TiVNbZrFe starts to release hydrogen at about 209 °C, nearly 170 °C lower than that of the pure MgH2. Also, it can be hydrogenated at room temperature and under 1 bar hydrogen pressure. Moreover, a stable reversible capacity up to 6.16 wt% is observed after 100 cycles. The apparent activation energy of dehydrogenating MgH2–TiVNbZrFe can be reduced to 63.03 kJ mol−1, which is about 90 kJ mol−1 lower than that of pure MgH2.