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Abstract: Lithium alanate (LiAlH4) is of particular interest as one of the most promising candidates for solid‐state hydrogen storage. Unfortunately, high dehydrogenation temperatures and relatively slow kinetics limit its practical applications. Herein, 3D flower‐like nanocrystalline Ni/C, composed of highly dispersed Ni nanoparticles and interlaced carbon flakes, was synthesized in situ. The as‐synthesized nanocrystalline Ni/C significantly decreased the dehydrogenation temperature and dramatically improved the dehydrogenation kinetics of LiAlH4. It was found that the LiAlH4 sample with 10 wt % Ni/C (LiAlH4‐10 wt %Ni/C) began hydrogen desorption at approximately 48 °C, which is very close to ambient temperature. Approximately 6.3 wt % H2 was released from LiAlH4‐10 wt %Ni/C within 60 min at 140 °C, whereas pristine LiAlH4 only released 0.52 wt % H2 under identical conditions. More importantly, the dehydrogenated products can partially rehydrogenate at 300 °C under 4 MPa H2. The synergetic effect of the flower‐like carbon substrate and Ni active species contributes to the significantly reduced dehydrogenation temperatures and improved kinetics. [ABSTRACT FROM AUTHOR]

Abstract: Lithium alanate (LiAlH4) is of particular interest as one of the most promising candidates for solid‐state hydrogen storage. Unfortunately, high dehydrogenation temperatures and relatively slow kinetics limit its practical applications. Herein, 3D flower‐like nanocrystalline Ni/C, composed of highly dispersed Ni nanoparticles and interlaced carbon flakes, was synthesized in situ. The as‐synthesized nanocrystalline Ni/C significantly decreased the dehydrogenation temperature and dramatically improved the dehydrogenation kinetics of LiAlH4. It was found that the LiAlH4 sample with 10 wt % Ni/C (LiAlH4‐10 wt %Ni/C) began hydrogen desorption at approximately 48 °C, which is very close to ambient temperature. Approximately 6.3 wt % H2 was released from LiAlH4‐10 wt %Ni/C within 60 min at 140 °C, whereas pristine LiAlH4 only released 0.52 wt % H2 under identical conditions. More importantly, the dehydrogenated products can partially rehydrogenate at 300 °C under 4 MPa H2. The synergetic effect of the flower‐like carbon substrate and Ni active species contributes to the significantly reduced dehydrogenation temperatures and improved kinetics. [ABSTRACT FROM AUTHOR]

Lithium borohydride (LiBH4) with a theoretical hydrogen storage capacity of 18.5 wt % has attracted intense interest as a high-density hydrogen storage material. However, high dehydrogenation temperatures and limited kinetics restrict its practical applications. In this study, mesoporous nickel- and cobalt-based oxide nanorods (NiCo2O4, Co3O4 and NiO) were synthesized in a controlled manner by using a hydrothermal method and then mixed with LiBH4 by ball milling. It is found that the dehydrogenation properties of LiBH4 are remarkably enhanced by doping the as-synthesized metal oxide nanorods. When the mass ratio of LiBH4 and oxides is 1:1, the NiCo2O4 nanorods display the best catalytic performance owing to the mesoporous rod-like structure and synergistic effect of nickel and cobalt active species. The initial hydrogen desorption temperature of the LiBH4-NiCo2O4 composite decreases to 80 °C, which is 220 °C lower than that of pure LiBH4, and 16.1 wt % H2 is released at 500 °C for the LiBH4-NiCo2O4 composite. Meanwhile, the composite also exhibits superior dehydrogenation kinetics, which liberates 5.7 wt % H2 within 60 s and a total of 12 wt % H2 after 5 h at 400 °C. In comparison, pure LiBH4 releases only 5.3 wt % H2 under the same conditions. [ABSTRACT FROM AUTHOR]