A novel Ce0.8Fe0.1Zr0.1O2solid solution with high catalytic activity for hydrogen storage in MgH2

Abstract

The effect of the solid solution Ce0.8Fe0.1Zr0.1O2, successfully prepared by a hydrothermal synthesis method, on the hydrogen sorption properties of MgH2 is systemically investigated. The Ce0.8Fe0.1Zr0.1O2-modified MgH2 composite exhibits remarkable hydrogen kinetics properties and thermodynamics behavior compared to those of as-milled MgH2, with a reduction in the initial desorption temperature of approximately 82 K. With respect to the hydrogen kinetics, the Ce0.8Fe0.1Zr0.1O2-added sample could uptake approximately 5.3 wt% H2 at 473 K in 2500 s, whereas only 1.5 wt% hydrogen could be absorbed by pristine MgH2 in the same conditions. Furthermore, about 4.5 wt% of hydrogen could be desorbed by Ce0.8Fe0.1Zr0.1O2-doped MgH2 composite at 623 K, which was 2 wt% higher than the as-milled MgH2 sample over the same period of time. The decomposition apparent activation energy for MgH2-Ce0.8Fe0.1Zr0.1O2 is reduced to 84.3 kJ mol-1, which is about 77 kJ mol-1 lower than that of pristine MgH2. It is believed that the notable improvement in the hydrogen sorption kinetics is due to the in situ-formed active species of CeH2.51 and MgO as well as the abundant oxygen vacancies, which play a vital role in catalyzing the hydrogen sorption performance of MgH2.