Improvement effect of reversible solid solutions Mg₂Ni(Cu)/ Mg₂Ni(Cu)H₄ on hydrogen storage performance of MgH₂

Highlights

• Core-shell NiCu@C nanoparticles (∼15 nm) were prepared successfully.

• MgH₂–11 wt.% NiCu@C has excellent hydrogen absorption/desorption performances.

• The apparent activation energy (E_a) of dehydrogenated reaction is 77.2 ± 4.5 kJ/mol.

• The strengthening “hydrogen pumping” effect of Mg₂Ni(Cu)/Mg₂Ni(Cu)H₄ is revealed.

Abstract

The hydrogen absorption/desorption kinetic properties of MgH₂ can be effectively enhanced by doping specific catalysts. In this work, MOFs-derived NiCu@C nanoparticles (∼15 nm) with regular core-shell structure were successfully prepared and introduced into MgH₂ (denoted as MgH₂NiCu@C). The onset and peak temperatures of hydrogen desorption of MgH₂–11 wt.% NiCu@C are 175.0 °C and 282.2 °C, respectively. The apparent activation energy of dehydrogenated reaction is 77.2 ± 4.5 kJ/mol for MgH₂–11 wt.% NiCu@C, which is lower than half of that of the as-milled MgH₂. Moreover, MgH₂–11 wt.% NiCu@C displays great cyclic stability. The strengthening “hydrogen pumping” effect of reversible solid solutions Mg₂Ni(Cu)/Mg₂Ni(Cu)H₄ is proposed to explain the remarkable improvement in hydrogen absorption/desorption kinetic properties of MgH₂. This work offers a novel perspective for the design of bimetallic nanoparticles and beyond for application in hydrogen storage and other energy related fields.