Lewis and Brønsted acid synergistic catalysis in zeolite for boosting hydrogen storage performance of LiBH4

High-capacity LiBH 4 is a promising solid hydrogen storage material. However, the large electron cloud density between the B-H bonds in LiBH 4 induces high dehydrogenation temperatures and sluggish dehydrogenation kinetics. To solve the above problems, it is proposed to enhance the hydrogen storage properties of LiBH 4 through the synergistic effect of Brønsted and Lewis acid in Hβ zeolite. Composite hydrogen storage systems with different mass ratios were prepared by simple ball-milling. At a LiBH 4 -to-Hβ mass ratio of 6:4, the 6LiBH 4 -4Hβ system released hydrogen at 190 °C and achieved a hydrogen release capacity of 7.0 wt% H 2 upon heating to 400 °C. More importantly, the hydrogen release capacity of the system reached 6.02 wt% at 350 °C under isothermal conditions after 100 min and 7.2 wt% at 400 °C under isothermal conditions after 80 min, whereas the pristine LiBH 4 only achieved 2.2 wt%. The improvement in hydrogen storage performance of the system was mainly attributed to two factors: (i) Lewis acid sites with acceptable electrons in the Hβ weaken the electron density of B–H bonds in LiBH 4 , and (ii) the H + proton from the Brønsted acid sites and H − of LiBH 4 undergo a H +  + H −  = H 2 reaction. Theoretical calculations revealed that the Lewis and Brønsted acid sites in the Hβ zeolite are conducive to the weakening of B – H bonds and that storage charge transfer occurs near the Lewis acid sites. The present work provides new insights into improving the hydrogen storage performance of LiBH 4 by weakening the B–H bonds in the LiBH 4 .