Editorial
04 September 2020
Yongfeng Liu
, Hai-Wen Li
and
Zhenguo Huang
Editorial: Metal Hydride-Based Energy Storage and Conversion Materials
Editors
3
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Original Research
15 May 2020
Xin Zhang
, 5 more and
Yongfeng Liu
In this paper, we report amorphous-carbon-supported TiB2 nanoparticles having sizes of 2–4 nm (nano-TiB2@C) as highly active catalysts for hydrogen storage in NaAlH4. Nano-TiB2@C was synthesized by a simple calcination at 550°C with Cp2TiCl2 and MgB2 (molar ratio of 1:1) as precursors. The addition of 7 wt% nano-TiB2@C reduced the onset dehydrogenation temperature of NaAlH4 by 100 to 75°C. A practically available hydrogen capacity of 5.04 wt% could be desorbed at 140°C within 60 min, and completely hydrogenated at 100°C within 25 min under a hydrogen pressure of 100 bar. Notably, the hydrogen capacity was almost unchanged after 20 cycles, which shows the stable cyclability, considerably higher than those of structures catalyzed by Ti halides or TiO2. The stable catalytic function was closely related to the in-situ-formed Ti–Al alloy, which considerably facilitated the dissociation and recombination of H–H and Al–H bondings.
Original Research
15 April 2020
Kaiyao Wu
, 5 more and
Huai-Jun Lin
2,379 views
10 citations
Original Research
24 March 2020
To improve the hydrogen storage properties of Mg/MgH2, a Ni and TiO2 co-doped reduced graphene oxide [(Ni-TiO2)@rGO] nanocomposite is synthesized by a facile impregnation method and introduced into Mg via ball milling. The results demonstrated that the dispersive distribution of Ni and TiO2 with a particle size of 20–200 nm in the reduced graphene oxide matrix led to superior catalytic effects on the hydrogen storage properties of Mg-(Ni-TiO2)@rGO. The initial hydrogenation/dehydrogenation temperature for Mg-(Ni-TiO2)@rGO decreased to 323/479 K, 75/84 K lower than that of the additive-free sample. The hydrogen desorption capacity of the Mg-(Ni-TiO2)@rGO composite released 1.47 wt.% within 120 min at 498 K. When the temperature was increased to 523 K, the hydrogen desorption capacity increased to 4.30 wt.% within 30 min. A hydrogenation/dehydrogenation apparent activation energy of 47.0/99.3 kJ·mol−1 was obtained for the Mg-(Ni-TiO2)@rGO composite. The improvement in hydrogenation and dehydrogenation for the Mg-(Ni-TiO2)@rGO composite was due to the reduction of the apparent activation energy by the catalytic action of (Ni-TiO2)@rGO.
Original Research
07 April 2020
Ke Wang
and
Qibo Deng
2,542 views
18 citations
Original Research
19 February 2020
Magnesium Nanoparticles With Pd Decoration for Hydrogen Storage
Yana Liu
, 4 more and
Liquan Li
In this work, Magnesium nanoparticles with Pd decoration, ranging from 40 to 70 nm, were successfully coprecipitated from tetrahydrofuran (THF) solution, assigned as the Mg–Pd nanocomposite. The Mg–Pd nanocomposite exhibits superior hydrogen storage properties. For the hydrogenated Mg–Pd nanocomposite at 150°C, the onset dehydrogenation temperature is significantly reduced to 216.8°C, with a lower apparent activation energy for dehydrogenation of 93.8 kJ/mol H2. High-content γ-MgH2 formed during the hydrogenation process, along with PH0.706, contributes to the enhancing of desorption kinetics. The Mg–Pd nanocomposite can take up 3.0 wt% hydrogen in 2 h at a temperature as low as 50°C. During lower hydrogenation temperatures, Pd can dissociate hydrogen and create a hydrogen diffusion pathway for the Mg nanoparticles, leading to the decrease of the hydrogenation apparent activation energy (44.3 kJ/mol H2). In addition, the Mg–Pd alloy formed during the hydrogenation/dehydrogenation process can play an active role in the reversible metal hydride transformation, destabilizing the MgH2.
Original Research
28 January 2020
Activity-Tuning of Supported Co–Ni Nanocatalysts via Composition and Morphology for Hydrogen Storage in MgH2
Xiaoli Ding
, 4 more and
Qingan Zhang
Developing cheap metal nanocatalysts with controllable catalytic activity is one of the critical challenges for improving hydrogen storage in magnesium (Mg). Here, it is shown that the activity of graphene-anchored Co–Ni nanocatalysts can be regulated effectively by tuning their composition and morphology, which results in significantly improved hydrogen storage in Mg. The catalytic activity of supported Co–Ni nanocatalysts is demonstrated to be highly dependent on their morphology and composition. When Ni was partly substituted by Co, the shape of these nanocatalysts was changed from spherical to plate-like, thus corresponding to a decrease in activity. These alterations intrinsically result in enhanced hydrogen storage properties of MgH2, i.e., not only does it exhibit a decreased peak desorption temperature but also a positive change in the initial activation for sorption. The results obtained provide a deep understanding of the tuning of catalytic activity via composition and morphology and further provide insights into improving hydrogen storage in Mg-based materials.
Original Research
04 February 2020
Yanping Fan
, 5 more and
Baozhong Liu
3,332 views
9 citations
Original Research
15 January 2020
Haizhen Liu
, 11 more and
Jin Guo
Aluminum hydride (AlH3) is a promising candidate for hydrogen storage due to its high hydrogen density of 10 wt%. Several polymorphs of AlH3 (e.g., α, β, and γ) have been successfully synthesized by wet chemical reaction of LiAlH4 and AlCl3 in ether solution followed by desolvation. However, the synthesis process of α'-AlH3 from wet chemicals still remains unclear. In the present work, α'-AlH3 was synthesized first by the formation of the etherate AlH3 through a reaction of LiAlH4 and AlCl3 in ether solution. Then, the etherate AlH3 was heated at 60°C under an ether gas atmosphere and in the presence of excess LiAlH4 to remove the ether ligand. Finally, α'-AlH3 was obtained by ether washing to remove the excess LiAlH4. It is suggested that the desolvation of the etherate AlH3 under an ether gas atmosphere is essential for the formation of α'-AlH3 from the etherate AlH3. The as-synthesized α'-AlH3 takes the form of rod-like particles and can release 7.7 wt% hydrogen in the temperature range 120–200°C.
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