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Modulated noble metal/2D MOF heterostructures for improved hydrogen storage of MgH2
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DOI：10.1007/s12598-023-02496-6.png)
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Abstract
En 中文
The conjugation of external species with two-dimensional (2D) materials has broad application prospects. In this study, we have explored the potential of noble metal/2D MOF heterostructures in hydrogen storage. Specifically, the MgH2-Ni-MOF@Pd system has shown remarkable hydrogen desorption/sorption performances, starting to liberate hydrogen at 181 degrees C, which is 230 degrees C lower than that of pristine MgH2. Under the catalytic effect of Ni-MOF@Pd, the dehydrogenation apparent activation energy of MgH2 is noticeably decreased from (133.5 +/- 17.5) to (34.58 +/- 1.87) kJmol(-1), and the hydrogenation apparent activation energy is reduced from (70.41 +/- 7.43) to (25.78 +/- 4.64) kJmol(-1), which is lowered by 63.4%. The fully-dehydrogenated MgH2-Ni-MOF@Pd composite rapidly uptakes hydrogen, with 2.62 wt% at 100 degrees C and 6.06 wt% at 150 degrees C within 300 s, respectively. The mechanism analysis of MgH2 catalyzed by Ni-MOF@Pd has revealed that the transformation of Mg2Ni and Mg2NiH4 could act as a hydrogen pump, providing numerous channels for fast diffusion and transport of hydrogen atoms. Moreover, in the dehydrogenation process, the element Pd reacts with MgH2 to form the Mg-Pd alloy phase, which makes MgH2 take precedence to decompose through the Mg-Pd alloy rather than self-decomposition, further reducing thermal stability and improving de/hydrogenation kinetics. The synergistic effect of Mg-Pd, Mg2Ni, and the special ultra-thin 2D sheet structure of the additive is the main reason for the good hydrogen storage property of MgH2-Ni-MOF@Pd. Our findings provide inspiration for designing efficient multi-functional additives with unique morphologies to optimize the hydrogen desorption/sorption behaviors of hydrogen storage materials.
Keywords:
Hydrogen storage
Magnesium hydride
2D metal-organic framework nanosheets
Ni/Pd
Synergistic catalysis
Journal
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11
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4.9K
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