Improved hydrogen storage properties of MgH2 by addition of Co2NiO nanoparticles
A sample of MgH2 and 10 wt% Co2NiO was prepared by the ball milling technique. The hydrogen storage properties and reaction mechanism of the sample were examined. The temperature-programmed desorption result shows that the addition of 10 wt% Co2NiO to MgH2 exhibited a lower onset desorption temperature of 300 °C, which was decreased to 117 and 70 °C compared to as-received and as-milled MgH2, respectively. The de/rehydrogenation kinetics of MgH2 + 10 wt% Co2NiO showed improvement compared to un-doped MgH2. The results of the Kissinger plot shows that the activation energy for the hydrogen desorption of MgH2 was reduced to about 65.0 and 15.0 kJ mol−1 compared to as-received and as-milled MgH2, respectively. Meanwhile, the X-ray diffraction analysis shows the formation of a new phase of Mg–Co alloy and Co1.29Ni1.71O4 after the dehydrogenation and rehydrogenation process. It is reasonable to conclude that the Co2NiO additive plays a catalytic role through the formation of active species of Mg–Co alloy and Co1.29Ni1.71O4 during the heating process, thus improving the hydrogen storage properties of MgH2.