Effect of the hierarchical Co@C nanoflowers on the hydrogen storage properties of MgH2

A hierarchical Co@C nanoflowers are synthesized via a simple route based on a low temperature solid-phase reaction. The as-prepared hierarchical Co@C nanoflowers have an enhanced catalytic activity on the hydrogen storage properties of MgH2 and thermodynamics and kinetics properties of the MgH2-Co@C composite are systematically researched. It is found that the initial desorption temperature of the MgH2-Co@C is about 201 degrees C, 99 degrees C lower compared to MgH2. And the MgH2-Co@C material can release 5.74 wt % within 30 min and 6.08 wt % H-2 within 60 min at 300 degrees C. Whereas, pure as-milled MgH2 only can release 0.37 wt % within 30 min and 1.20 wt % hydrogen within 60 min at the same temperature. Meanwhile, the hydrogen absorption amount of MgH2-Co@C achieve 5.96 wt % within 10 min at 300 degrees C, and the maximum hydrogen absorption amount reach 6.16 wt% within 20 min. In addition, the introduction of hierarchical Co@C nanoflowers also reduces the activation energy (E-a) 46 kJ mol(-1), which exhibits a promoted kinetics. In addition, the relative hydrogen desorption mechanism of MgH2-Co@C has also been discussed. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.