Amorphous VB2 nanoparticles for stable hydrogen storage of 2LiBH4–MgH2
As a typical reactive composite hydrogen storage system, 2LiBH 4 –MgH 2 holds an ultrahigh hydrogen storage capacity of 11.5 wt%. However, it suffers from sluggish hydrogen storage kinetics due to the difficult nucleation of MgB 2 . Herein, amorphous VB 2 nanoparticles with an average size of approximately 32 nm are synthesized to enhance the hydrogen storage performance of 2LiBH 4 –MgH 2 composite. VB 2 , sharing the same hexagonal structure with MgB 2 with a d -value mismatch ratio of only 2.28%, could serve as effective nucleation sites for promoting the formation of MgB 2 . Theoretical calculations reveal that the introduction of VB 2 significantly reduces the binding energies of B and Mg, facilitating in situ nucleation of MgB 2 . As a result, after the introduction of VB 2 nanoparticles, complete hydrogen desorption of 9.23 wt% is achieved for 2LiBH 4 -MgH 2 within 2 h at 400 °C, which is 4 times shorter than the time required for pure 2LiBH 4 -MgH 2 , and no nucleation incubation period for hydrogen desorption is observed even at a low temperature of 380 °C. More importantly, a reversible capacity of 9.3 wt%, corresponding to a capacity retention of 100%, could be preserved after 10 cycles of hydrogen storage, demonstrating stable reversible hydrogen storage performance. This study provides a novel technological pathway for improving the reversible hydrogen storage performance of composite metal hydrides and offers significant insights into the development of high-performance hydrogen storage materials. Graphical
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