Nitrogen-Doped Graphene-Supported Nickel Nanoparticles Reveal Low Dehydrogenation Temperature and Long Cyclic Life of Magnesium Hydrides
Muhammad Imran, Jaffer Saddique, Chengzhang Wu, Muneeb Ur Rahman, Zaheen Ullah Khan, Wajid Ali, Rong Zhang
Abstract
High Resolution Image Download MS PowerPoint Slide Magnesium hydride (MgH 2 ) is a promising hydrogen storage candidate due to its large capacity; however, high dehydrogenation temperature and slow kinetic rates are the main bottlenecks. Herein, we proposed a strategy for designing nitrogen-doped graphene-supported Ni nanoparticles (NPs) (Ni@NC) to tackle these problems. The results showed that the MgH 2 + 15 wt % Ni@NC nanocomposite reduced the on-set dehydrogenation temperature to 195 °C, which was 175 °C lower than pristine MgH 2 . In addition, MgH 2 + 15 wt % Ni@NC achieved 1.7 and 6.5 wt % desorption capacities at 225 and 300 °C, respectively, while absorbing 5.5 wt % hydrogen at 100 °C. The MgH 2 + 15 wt % Ni@NC nanocomposite showed high cyclic stability, achieving 98.0% capacity retention after 100 cycles at 270 °C with negligible loss in capacity. This remarkable hydrogen storage performance can be attributed to the homogeneous distribution of Ni NPs on N-doped graphene layers, in situ formed Mg 2 NiH 2 NPs, and multiphasic regions, promoting the nucleation and growth process during hydrogenation/dehydrogenation, which stabilized and improved the cyclic stability. This strategy paves the way to developing high-performance MgH 2 for large-scale applications.