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