A novel Ce_0.8Fe_0.1Zr_0.1O₂ solid solution with high catalytic activity for hydrogen storage in MgH₂

The effect of the solid solution Ce_0.8Fe_0.1Zr_0.1O₂, successfully prepared by a hydrothermal synthesis method, on the hydrogen sorption properties of MgH₂ is systemically investigated. The Ce_0.8Fe_0.1Zr_0.1O₂-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 Ce_0.8Fe_0.1Zr_0.1O₂-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 Ce_0.8Fe_0.1Zr_0.1O₂-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-Ce_0.8Fe_0.1Zr_0.1O₂ 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 CeH_2.51 and MgO as well as the abundant oxygen vacancies, which play a vital role in catalyzing the hydrogen sorption performance of MgH₂.