Abstract
To reveal the synergistic effect of nanoconfinement and metallic catalysis on the hydrogen storage properties of LiBH4, the nanoporous Ni-based alloy (np-Ni) was prepared herein by dealloying of the Mn70Ni30 alloy in (NH4)2SO4 solution, and then LiBH4 was loaded into np-Ni to construct the LiBH4/np-Ni hydrogen storage system using wet impregnation. It was found that dehydrogenation of the LiBH4/np-Ni (1:5) system starts at around 70°C and ends before 400°C, with ~11.9 wt.% of hydrogen desorbed. The apparent dehydrogenation activation energy for the LiBH4/np-Ni (1:5) system was remarkable decreased to about 11.4 kJ/mol. After rehydrogenation at 450°C under 8 MPa hydrogen pressure, ~8.2 wt.% of hydrogen can be released from about 60°C upon second dehydrogenation. These obtained results would provide an efficient strategy for improving the hydrogen storage properties of other metal borohydrides.
Highlights
Nowadays, the issue of energy shortage has been called into public focus
It can be seen that the Mn70Ni30 alloy before and after dealloying are both composed of a single phase of (Mn, Ni) solid solution with a Cu-type structure
The results indicate that the grain size and cell parameters of the sample were both decreased with the extraction of Mn atom from (Mn, Ni) solid solution upon dealloying due to that Mn has a larger atomic radius relative to Ni
Summary
The issue of energy shortage has been called into public focus. Hydrogen is considered to be the most ideal secondary source because of its high calorific value, low environmental impact and abundant resources (Abe et al, 2019). Taking into account that transition metal elements (e.g., Ni and Co) can serve as the active catalyst in improving the hydrogen storage properties of complex hydrides owing to their high electronegativity0 (Ngene et al, 2011; Liu et al, 2018; Zhang et al, 2018), a synergistic effect of nanoconfinement and catalysis would be achieved by confining LiBH4 in nanoporous transition metal Based on this consideration, nanoporous Ni-based alloy was prepared by dealloying of the Mn70Ni30 alloy and used as the carrier to support LiBH4 in this work, and a significantly improved low-temperature hydrogen storage in LiBH4 was successfully obtained. Fourier transform infrared (FTIR) spectrum was collected using a Nicolet 6700 FTIR spectrometer
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