Exceptional catalytic effect of novel rGO-supported Ni-Nb nanocomposite on the hydrogen storage properties of MgH 2

The design of an excellent active catalyst to improve the sluggish kinetic and thermodynamic properties of magnesium hydride (MgH 2 ) remains a great challenge to achieve its practical application. In this study, a novel Ni-Nb/rGO nanocomposite catalyst was successfully prepared by one-spot hydrothermal and subsequent calcination methods. The novel Ni-Nb/rGO nanocomposite exhibits an exceptional catalytic effect on improving MgH 2 sorption properties. Specifically, the onset desorption temperature of MgH 2 + 10 wt% Ni-Nb/rGO composite is reduced to 198 & DEG;C, much lower than that of undoped MgH 2 (330 & DEG;C). Interestingly, the composite can release 5.0, 5.9, and 6.0 wt% H 2 within 10 min at 245, 260, and 275 & DEG;C, respectively. Furthermore, the dehydrogenated MgH 2 + 10 wt% Ni-Nb/rGO composite starts to absorb hydrogen even at room temperature with approximate 2.75 wt% H 2 uptake at 75 & DEG;C under 3 MPa H 2 pressure within 30 min and exhibits excellent stability by maintaining 6.0 wt% hydrogen content after 20 cycles at 300 & DEG;C. Chou's model suggests that the de/hydrogenation kinetics of Ni-Nb/rGO-modified MgH 2 switches from surface penetration model to diffusion model at lower temperatures. Additionally, the activation energies ( E a ) for the de/hydrogenation of MgH 2 + 10 wt% Ni-Nb/rGO are reduced to 57.8 kJ/mol and 33.9 kJ/mol, which are significantly lower than those of undoped MgH 2 . The work demonstrates that the addition of a novel ternary Ni-Nb/rGO catalyst is an effective strategy to not only boost the sorption kinetics of MgH 2 but also maintain its cycling property. & COPY; 2023 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

A novel Ni-Nb/rGO nanocomposite catalyst was prepared and shown to exhibit exceptional catalytic effect in improving the sorption properties of magnesium hydride (MgH2). The composite catalyst significantly reduced the desorption temperature of MgH2, increased the hydrogen release capacity, and enabled hydrogen absorption even at room temperature. The addition of the composite catalyst was found to enhance the sorption kinetics and cycling property of MgH2.