Effect of carbon type (graphite, CFs and diamond) on the hydrogen desorption of Mg–C powder mixtures under microwave irradiation

Effect of microwave irradiation on hydrogen sorption properties of hand mixed MgH2 – 10 wt.% carbon fibers

“…On the other hand, it is important to highlight that the CFs are not affected by the irradiation after two microwave cycles and remain unchanged. This confirms the hypothesis previously mentioned: "the CFs should be considered as recyclable microwave receptors" [21]. Additionally, it is worth to note that most of the pulverized particles were not agglomerated into large cluster in 2-Microwaved-Mg powder (Fig.…”

“…3 shows the X-ray diffraction patterns of pure MgH 2 , MgH 2 e 10 wt.%CFs exposed for 20 s to microwave irradiation (Microwaved-Mg) and hydrogenated Microwaved-Mg after several hydriding/dehydriding cycles which will be named in this work "HMicrowaved-Mg". As already reported, the addition of carbon allows quick and high hydrogen desorption which can be clearly deduced by the appearance of the Bragg peaks related to Mg after 20 s of microwaves heating [21]. It is also worth pointing out that the peak at 26 has been attributed to C (i.e.…”

“…In order to get a better understanding of microwaves treatment on the sorption properties, the morphological aspect was observed by SEM. As mentioned previously [21], the magnesium powder obtained after 20 s of microwave treatment highlights pores and morphological defects like fractures and cracks which are due to the rapid gasedesorption reaction [22]. These particular morphologies contribute to the increase of the reactive surface area of the material and therefore to the metal/gas contact surface.…”

“…irradiated MgH 2 e 10 wt.% CFs for 20 s under 1500 W [21]) was measured. This powder having undergone a microwave treatment will be called in this study "Microwaved-Mg".…”

“…The heating rate of the samples depends on the both content of LiBH 4 and the microwave power. In our previous work [21], we investigated an extra rapid dehydrogenation of MgH 2 / carbon by using the microwaves method. In this case, Carbon additives transfer the heat generated from absorbed microwave irradiation to the MgH 2 matrix which induces the hydrogen release.…”