Remarkable kinetics of novel Ni@CeO2-MgH2 hydrogen storage composite

Magnesium hydroxide (MgH2) has excellent reversibility and high capacity, and is one of the most promising materials for hydrogen storage in practical applications. However, it suffers from high dehydrogenation temperature and slow sorption kinetics. Rare earth hydrides and transition metals can both significantly improve the de/hydrogenation ki-netics of MgH2. In this work, MgH2-Mg2NiH4-CeH2.73 is in-situ synthesized by introducing Ni@CeO2 into MgH2. The unique coating structure of Ni@CeO2 facilitates homogeneous distribution of synergetic CeH2.73 and Mg2NiH4 catalytic sites in subsequent ball milling process. The as-fabricated composite MgH2-10 wt% Ni@CeO2 powders possess superior hydrogenation/dehydrogenation characteristics, absorbing 4.1 wt% hydrogen within 60 min at 100 degrees C and releasing 5.44 wt% H2 within 10 min at 350 degrees C. The apparent activation energy of MgH2-10 wt% Ni@CeO2 is determined to be 84.8 kJ/mol and it has favorable hydrogen cycling stability with almost no decay in capacity after 10 cycles.(c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

Magnesium hydroxide (MgH2) is a promising material for hydrogen storage, but it has high dehydrogenation temperature and slow sorption kinetics. This study introduces rare earth hydrides and transition metals to improve the de/hydrogenation kinetics of MgH2. The synthesized MgH2-Mg2NiH4-CeH2.73 composite exhibits superior hydrogenation/dehydrogenation characteristics and cycling stability.