Efficient catalytic effect of the page-like MnCo2O4.5 catalyst on the hydrogen storage performance of MgH2

Abstract

Binary transition metal oxides have exhibited highly excellent de/hydrogenation kinetic catalytic properties on magnesium hydride (MgH₂). Thence, page-like MnCo₂O_4.5 nanoparticles have been synthesized to enhance the de/hydrogenation performance of MgH₂. The initial dehydrogenation temperature of the MgH₂-6 wt% MnCo₂O_4.5 composite decreases to 285 °C. Interestingly, MgH₂ doped with 6 wt% MnCo₂O_4.5 can fully release 6.4 wt% H₂ in 4 min at 325 °C. On the contrary, only 0.58 wt% of H₂ is released from the undoped as-milled MgH₂ in 4 min at 325 °C. Moreover, the dehydrogenated MnCo₂O_4.5 doped composite can absorb 4.43 wt% H₂ in 30 min at 150 °C. Moreover, we found that the desorption activation energy of the composite decreases by 50.18% compared with that of the undoped as-milled MgH₂. The evolution process and catalytic mechanism of MnCo₂O_4.5 on MgH₂ were explored through the evidence of X-ray diffraction and transmission electron microscopy. It is believed that Mn-containing phases and Co-containing phases formed in situ during the dehydrogenation process can synergistically catalyze MgH₂ to achieve better kinetic performance.