Nitrogen-doped hierarchically porous carbon derived from ZIF-8 and its improved effect on the dehydrogenation of LiBH4

Nitrogen-doped hierarchically porous carbon (NHPC) materials have been synthesized by using a zeolitic imidazolate framework, ZIF-8, as self-sacrificing template. The initial derived carbon (D-carbon) contains a 3-dimensional (3D) hierarchically porous carbon framework with rich nitrogen doping (11.22%). Chemical activation by KOH, the further activated carbon (Ac-carbon) shows a specific high surface area (2477 m2 g−1), but lower N content (1.99%). LiBH4-(D-carbon)/(Ac-carbon) is prepared by ball-milling method and the dehydrogenation performance of LiBH4 is significantly improved. More than 6.13 wt% H2 can be released from either of the two mixtures within 100 min at 320 °C, respectively, showing better dehydrogenation performance than that of pure LiBH4. Additionally, the controlled experiments reveal that those improved dehydrogenation properties of LiBH4 might be attributed to the synergetic contributions of high N heteroatom loading, large surface area and catalysis of carbon materials. We provided a simple method to prepare solely MOF-derived nitrogen-doped carbon materials, which might be a promising catalyst for the hydrogen storage materials.