In situ synthesized one-dimensional porous Ni@C nanorods as catalysts for hydrogen storage properties of MgH2

Abstract

We have demonstrated an extremely facile procedure for the preparation of 1D porous Ni@C nanostructures by pyrolysis of Ni-based coordination polymer nanorods. The highly aligned Ni-based polymer nanorods were prepared using nitrilotriacetic acid (NTA) as a chelating agent by a one-step solvothermal approach. The obtained precursors are demonstrated to have a well-designed 1D nanostructure and a 3D interconnected mesoporous texture. After thermal treatment, 1D porous Ni@C nanorods were obtained, which basically preserved the morphology of the precursors. In addition, the carbon in the porous Ni@C nanorods is in both crystalline and amorphous states. The as-prepared Ni@C sample displays nanorod-like morphology with about 3 μm length and about 200 nm diameter. With a large surface area of 161.4 m² g⁻¹, this novel material had a good catalytic effect on de/hydrogenation of MgH₂. The desorption peak temperature of MgH₂–5 wt% Ni@C composites can be lowered more than 57 °C than the pure as-milled MgH₂. The MgH₂–5 wt% Ni@C composite could desorb 6.4 wt% H₂ within 10 min at 300 °C, in contrast, only 2.3 wt% H₂ was desorbed even after 100 min for pure MgH₂. In addition, an activation energy of 108 kJ mol⁻¹ for the as-milled MgH₂–5 wt% Ni@C composites has been obtained, which exhibit an enhanced kinetics.