Investigating of hydrolysis kinetics and catalytic mechanism of Mg–Ce–Ni hydrogen storage alloy catalyzed by Ni/Co/Zn-based MOF

Abstract

In this research, Mg90Ce5Ni5 ingot alloys were prepared using the vacuum melting induction method. Subsequently, Ni/Zn/Co-based MOFs were synthesized via solvent thermal reaction. The phase composition and surface topography of the materials were tested using X-ray diffraction and scanning electron microscopy. The hydrogen production of Mg90Ce5Ni5 alloy in MgCl2 solution was studied. Avrami-Erofeev and Arrhenius's equations were utilized to fit the hydrogen production curve, studying hydrogen production kinetics and activation energy. The result shows that the alloy exhibits a faster initial hydrogen production rate after ball-milling, and the final hydrolysis yield is higher after hydrogenation. Compared to Mg90Ce5Ni5, Mg90Ce5Ni5 + 2 wt% MOF/Ni, and Mg90Ce5Ni5 + 2 wt% MOF/Zn, Mg90Ce5Ni5 + 2 wt% MOF/Co demonstrates the best hydrolysis performance (1112 mL g−1, activation energy of 12.9 ± 0.5 kJ mol−1). Due to the synergistic effect between CoO and MgH2, the absorption and release of hydrogen were promoted. The hydrogen production of the alloy after the introduction of MOF/Co reached 1730 mL g−1, and the activation energy was 18.5 ± 1.4 kJ mol−1. Optimizing the hydrolysis performance of the Mg90Ce5Ni5 alloy was achieved by introducing a MOF catalyst through ball milling. This structure-performance relationship provides an efficient modification strategy for synthesizing magnesium alloys with excellent kinetics.