Catalytic effects of V- and O-species derived from PrF3/V2C for efficient hydrogen storage in MgH2

Magnesium hydride (MgH2) is considered as an ideal hydrogen storage material with excellent hydrogen capacity, but the slow kinetics impedes its application. Herein, an efficient additive of V2C MXene-anchored PrF3 nanoparticles (PrF3/V2C) was synthesized, which presents excellent catalytic effect in improving the reversibility and stability of hydrogen storage in MgH2. The initial dehydrogenation temperature of the 5 wt.% PrF3/V2C-containing MgH2 (182 °C) is 105 °C lower than that of pure MgH2, and 6.5 wt.% hydrogen is rapidly released from 5 wt.% PrF3/V2C-added MgH2 sample in 6 min at 240 °C. In addition, 5 wt.% PrF3/V2C-containing MgH2 sample possesses outstanding reversible hydrogen storage capability of 6.5 wt.% after 10 cycles of dehydrogenation and hydrogenation. Microstructure analysis shows that the introduction of Pr improves the stability of V-species (V0 and V2+) and O-species (lattice oxygen (OL) and vacancy oxygen (OV)) formed during ball milling, promotes the interaction between V-species and O-species, and enhances their reversibility, which contributes to the significant improvement in re/dehydrogenation reversibility and cycling stability of MgH2. This study provides effective ideas and strategies for the purpose of designing and fabricating high-efficient catalysts for solid-state hydrogen storage materials.