NiB nanoparticles: A new nickel-based catalyst for hydrogen storage properties of MgH_2

摘要

In this paper, amorphous NiB nanoparticles were fabricated by chemical reduction method and the effect of NiB nanoparticles on hydrogen desorption properties of MgH_2 was investigated. Measurements using temperature-programmed desorption system (TPD) and volumetric pressure-composition isotherm (PCI) revealed that both the desorption temperature and desorption kinetics have been improved by adding 10 wt% amorphous NiB. For example, the MgH_2-10 wt%NiB mixture started to release hydrogen at 180 ℃, whereas it had to heat up to 300 ℃ to release hydrogen for the pure MgH_2. In addition, a hydrogen desorption capacity of 6.0wt% was reached within 10 min at 300 ℃ for the MgH_2 -10 wt%NiB mixture, in contrast, even after 120 min only 2.0 wt% hydrogen was desorbed for pure MgH_2 under the same conditions. An activation energy of 59.7 kJ/mol for the MgH_2/ NiB composite has been obtained from the desorption data, which exhibits an enhanced kinetics possibly due to the additives reduced the barrier and lowered the driving forces for nucleation. Further cyclic kinetics investigation using high-pressure differential scanning calorimetry technique (HP-DSC) indicated that the composite had good cycle stability.