Vermiform Ni@CNT derived from one-pot calcination of Ni-MOF precursor for improving hydrogen storage of MgH2
(1. School of Environmental and Material Engineering, Yantai University, Yantai 264005, China;
2. Key Laboratory of Aerospace Materials and Performance, Ministry of Education, School of Materials Science and Engineering, Beihang University, Beijing 100191, China)
2. Key Laboratory of Aerospace Materials and Performance, Ministry of Education, School of Materials Science and Engineering, Beihang University, Beijing 100191, China)
Abstract: The Ni-coated carbon nanotubes (Ni@CNT) composite was synthesized by the facile “filtration + calcination” of Ni-based metal-organic framework (MOF) precursor and the obtained composite was used as a catalyst for MgH2. MgH2 was mixed evenly with different amounts of Ni@CNT (2.5, 5.0 and 7.5, wt.%) through ball milling. The MgH2-5wt.%Ni@CNT can absorb 5.2 wt.% H2 at 423 K in 200 s and release about 3.75 wt.% H2 at 573 K in 1000 s. And its dehydrogenation and rehydrogenation activation energies are reduced to 87.63 and 45.28 kJ/mol (H2). The in-situ generated Mg2Ni/Mg2NiH4 exhibits a good catalytic effect due to the provided more diffusion channels that can be used as “hydrogen pump”. And the presence of carbon nanotubes improves the properties of MgH2 to some extent.
Key words: Mg-based hydrogen storage material; activation energy; Ni-loaded carbon nanotubes; catalyst; mechanism