Effects of VF 4 on the hydriding cycling at 373 K and dehydriding of Mg 99 Ni prepared by hydriding combustion synthesis and mechanical milling (HCS+MM)

Effect of Few-Layer Ti3C2Tx Supported Nano-Ni via Self-Assembly Reduction on Hydrogen Storage Performance of MgH2

“…17,18 Controlling the morphology of the catalyst such as size, shape, and dispersion can effectively change catalytic activity, which also works in MgH 2 doped with the Ni system. 13,19,20 Ni particles with superb dispersion and ultrafine particle size showed the best catalytic activity among Ni-based catalysts with different morphologies reported by Zhang et al 14 Extensive research studies have been carried out on carbon materials as supporting materials to further improve the dispersion and alleviate the possible agglomeration of Ni particles as a catalytic phase to improve the efficiency of ball grinding and facilitate the electron transfer. 18,21 However, inherent problems of carbon materials such as relatively single element composition and limited catalytic activity compared to metals and their compounds restrict the improvement for the catalytic activity of Ni-based catalysts.…”

“…Various catalysts covering carbon materials, , rare earth metals, ,, transition metals, − metallic fluorides, and so on have been widely used as the addition. Particular emphasis has been put on the transition metals, which can weaken the Mg–H bonds and destabilize the MgH 2 because hydrogen atoms tend to form covalent bonds with transition metal elements rather than ionic bonds with magnesium atoms. , Of these, the Ni-based catalysts have been proved to have potential in the MgH 2 system, which was ascribed to the optimized morphology of Ni or the interaction effect by introducing another phase. , Controlling the morphology of the catalyst such as size, shape, and dispersion can effectively change catalytic activity, which also works in MgH 2 doped with the Ni system. ,, Ni particles with superb dispersion and ultrafine particle size showed the best catalytic activity among Ni-based catalysts with different morphologies reported by Zhang et al Extensive research studies have been carried out on carbon materials as supporting materials to further improve the dispersion and alleviate the possible agglomeration of Ni particles as a catalytic phase to improve the efficiency of ball grinding and facilitate the electron transfer. , However, inherent problems of carbon materials such as relatively single element composition and limited catalytic activity compared to metals and their compounds restrict the improvement for the catalytic activity of Ni-based catalysts. , In contrast, extra adding phases like transitional metal and its oxides and fluorides may enhance the overall catalytic activity of Ni-based catalysts such as the interfacial effect between Ni and Nb 2 O 5 in the MgH 2 /5Ni/5Nb 2 O 5 composite and the synergetic effect between Ni and CeH 2.37 in the Mg 80 Ce 18 Ni 2 composite . Therefore, for Ni-based catalysts, finding a catalytic phase that can not only act as a dispersant like carbon materials with a large surface area but also have high catalytic activity is an urgent need.…”

Fast Hydrogen Sorption Kinetics in Mg-VCl3 Produced by Cryogenic Ball-Milling

“…To date, several materials have been tried as additives or catalysts using different processing techniques. The list of additives or catalysts includes but is not limited to oxides such as Nb 2 O 5 [ 9 , 10 ], intermetallics such as Mg 2 Ni [ 11 ], metallic alloys such as NiMn 9.3 Al 4.0 Co 14.1 Fe 3.6 [ 12 ], transition metals [ 10 , 13 ], transition metals halides [ 14 , 15 , 16 ], metallic nanoparticles such as Ni [ 17 ], sulfides [ 18 ], co-catalysts of different substances [ 11 , 14 ], and many other compounds. The role of the catalyst is to enhance the dissociation and recombination rate of hydrogen and to improve H diffusion as a “hydrogen pump” [ 19 ].…”

“…V-containing compounds are interesting catalysts because of their affinity towards electrons due to unoccupied d orbitals [ 20 ]. VF 4 added to Mg 99 Ni was proposed to form VH 0.91 and MgF 2 during mechanical milling [ 15 ]. In that work, the VH 0.91 was acting as a hydrogen pump [ 15 ].…”

“…VF 4 added to Mg 99 Ni was proposed to form VH 0.91 and MgF 2 during mechanical milling [ 15 ]. In that work, the VH 0.91 was acting as a hydrogen pump [ 15 ]. Other V-containing compounds have improved the hydriding/dehydriding of Mg/MgH 2 [ 15 , 21 , 22 , 23 ].…”