Hydrogen storage properties of MgH2 + 20 wt.% Na2WO4 composite

• The influence of Na2WO4 effect on MgH2 hydrogen storage properties is studied.
• Activation energy of MgH2 desorption is remarkably reduced with the dopant of Na2WO4.
• The improvement can be attributed to MgWO4 formation during ball milling.

The hydrogen storage properties of MgH2 ball milled with 20 wt.% Na2WO4 have been investigated. The MgH2 + 20 wt.% Na2WO4 composite has favorable hydrogenation and dehydrogenation properties as well as low decomposition temperature. When compared with the pristine MgH2, the total hydrogen absorption capacity of MgH2 + 20 wt.% Na2WO4 composite increased from 0.98 wt.% to 2.27 wt.% in 20 min at 423 K, and the maximum hydrogen desorption capacity of MgH2 + 20 wt.% Na2WO4 composite increased by 1.3 wt.% at 573 K. DTA and the Kissinger desorption kinetics analysis results indicated that the dehydrogenation activation energy of MgH2 + 20 wt.% Na2WO4 composite is 83.10 kJ/mol, 39 kJ/mol lower than that of the pristine MgH2. The XRD pattern provided that the in-situ formed MgWO4, acting as the catalyst during ball milling, improved the hydrogen storage properties of MgH2.

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