Ni, beyond thermodynamic tuning, maintains the catalytic activity of V species in Ni3(VO4)2 doped MgH2

Abstract

Magnesium hydride has been regarded as a promising hydrogen storage material. However, its further commercialization is severely hampered by its stable thermodynamic and sluggish kinetic performance. Herein, to simultaneously solve above two problems, a bimetallic oxide Ni₃(VO₄)₂ has been synthesized and applied to catalyze the hydrogen storage reaction of MgH₂. Benefiting from the formation of the Mg₂Ni alloy, as well as kinetic modulation of V, the dehydrogenation temperature decreased to 210 °C, with a promising rehydrogenation capacity of 2.3 wt% near room temperature. X-ray absorption spectroscopy was employed to comprehensively reveal local structures of Ni and V in different states, with the detection of NiV₂O₄ intermediate active species for the first time. This work not only elucidates the structure evolution of the Ni₃(VO₄)₂ catalyst, but also clarifies the synergistic effect between Ni and V, which sheds light on further rational designs for multi-element metallic catalysts.