Improved Dehydrogenation Properties of LiBH 4 Using Catalytic Nickel- and Cobalt-based Mesoporous Oxide Nanorods.

Lithium borohydride (LiBH4) with a theoretical hydrogen storage capacity of 18.5wt% 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 degrees C, which is 220 degrees C lower than that of pure LiBH4, and 16.1wt% H-2 is released at 500 degrees C for the LiBH4-NiCo2O4 composite. Meanwhile, the composite also exhibits superior dehydrogenation kinetics, which liberates 5.7 wt% H-2 within 60s and a total of 12 wt% H-2 after 5h at 400 degrees C. In comparison, pure LiBH4 releases only 5.3wt% H-2 under the same conditions.