Porous Ni nanofibers with enhanced catalytic effect on the hydrogen storage performance of MgH₂

Abstract

Porous Ni nanofibers (NFs) were synthesized via a single-nozzle electrospinning technique with subsequent calcination and reduction. The as-prepared continuous Ni NFs, with a uniform diameter of ∼50 nm and porous structure composed of a myriad of Ni nanocrystallites, were adopted to catalyze MgH₂. The homogeneous distribution of Ni nanoparticles (NPs), obtained by ball milling Ni NFs with MgH₂, on the surface of MgH₂ offered effective catalytic sites to significantly enhance the hydrogen storage properties of MgH₂. In particular, 4% Ni NF catalyzed MgH₂ (MgH₂–4% Ni NFs) starts to release hydrogen at only 143 °C, with a peak temperature of 244 °C, 157 °C and 96 °C lower than for MgH₂ catalyzed with as-milled 4% Ni powders (MgH₂–4% Ni powders), and it dehydrogenates completely within only 11 min at 325 °C (7.02 wt%). Compared with plain MgH₂ and MgH₂–4% Ni powders, the activation energy of the as-milled MgH₂–4% Ni NF composite is significantly decreased to 81.5 kJ mol⁻¹.