Mg-Ti nanoparticles with superior kinetics for hydrogen storage

Mg nanoparticles (NPs) with addition of Ti catalysts were synthesised by inert gas condensation and in situ hydrogenation at 150 degrees C. The NPs size and composition were systematically investigated by scanning electron microscopy, energy dispersive X-ray spectroscopy and powder X-ray diffraction (PXD), while time resolved in situ synchrotron radiation-PXD was used to monitor the mechanism for hydrogen uptake and release at 280 degrees C. The Mg Ti NPs reveal activation energies of 68 kJ mora for absorption and 78 kJ mol(-1) for desorption by isothermal kinetics analysis, similar to the lowest values reported in the literature for MgH2 using Nb2O5 as a catalyst. Hence, hydrogen desorption (p(des) = 8 mbar) and absorption (p(abs) = 260 mbar) is achieved at 200 degrees C in similar to 2000 s, while keeping 5.3 wt% storage capacity. Tshermodynamic data extracted from van 't Hoff plots reveal unchanged values compared to bulk MgH2. Therefore, the improved hydrogen storage performances are assigned to the enhanced kinetics only. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.