Perovskiet-like BaZrO3 nanocatalyst with rich oxygen vacancies on boosting hydrogen storage property of MgH2

Magnesium hydride (MgH2) as a promising solid hydrogen syorage material has been extensively researched. but the higher separating temperature and sluggish kinetics hinder its large-scale practical application. To solve this problem, a BaZrO3 nanocatalyst with abundant oxygen vancies is manuscripted, exerts significant improvement to the hydrogen storage performance of MgH2. Impressively, the onset dehydrogenation temperature of MgH210 wt% BaZrO3-Ov composite is reduced markedly from 390 degrees C(for pure MgH2) to 260 degrees C. Additionally, the composite can discharge 4.22 wt% H2 with 10 min at 275 degrees C and a total dehydrogenation amouut of 5.88 wt% is achieved at 300 degrees C. For hydrogen absorption, the composite can rapidly recharge hydrogen at a low temperature of 150 degrees C and approximately 5.08 wt% H2 can be absorbed at 275 degrees C within 10 min. The dehydrogenation activation energy of BaZrO3-Ov-added MgH2 is as low as 92.61 kJ mol- 1 compared to pure MgH2 (164.78 kJ mol- 1). Meantime, the composite presents unexceptionable reversible kinetic performance with a retention rate of 97.35 % after 10 cycles. The excellent catalytic effects can be attributed to the in-situ generation of ZrO2-Ov, BaO-Ov and ZrH2 from BaZrO3-Ov during the first de-/rehydrogenation cycle, which function as nanosized active sites on MgH2 matrix to accelerate electron transfer and provide abundant hydrogen diffusion channels. Density functional theory calculations results verify that the Mg-H length and dehydrogenation energy barrier are ameliorated through BaZrO3-Ov. This work provides a unique perspective on modification MgH2 by perovskietlike BaZrO3-Ov nanocatalyst.