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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