Enhancing Reversible Hydrogen Storage Performance of LiBH Catalyzed by N-Doped Carbon Nanosheet Networks Embedded with Co Nanoparticles.

LiBH is one of the most promising candidates for onboard solid-state hydrogen storage. Nevertheless, the implementation of this material in practical systems is limited due to its high operational temperature, slow kinetic behavior, and compromised reversible capacity. Herein, N-doped carbon nanosheet networks embedded with Co nanoparticles (Co/N-CNSNs) are designed as functional scaffolds to improve the hydrogen storage performance of LiBH. Co NPs and the formed CoB in Co/N-CNSNs during the initial hydrogen desorption process could catalytically weaken the B-H bonds in LiBH, resulting in the reduction of H dissociation energy to 0.34 and 0.31 eV, respectively, much lower than that of pure LiBH (1.95 eV). Benefiting from the synergistic effect of the catalytic role of Co NPs and the formed CoB and the nanoconfinement role of Co/N-CNSNs, 10.1 wt % hydrogen could be released from LiBH@Co/N-CNSNs at 300 °C within 180 min, while this value is decreased to only 1.5 wt % for bulk LiBH under the identical condition. Moreover, the homogeneous molecular interaction between Co/N-CNSNs and LiBH leads to the formation of σ-bonds between Li and the nonconjugated lone pair electrons of pyridinic N and pyrrolic N, which enables Co/N-CNSNs to act as anchoring sites for inhibiting the grain growth of LiBH, contributing to improving its reversibility. Hence, LiBH nanoconfined within Co/N-CNSNs demonstrates a reversible hydrogen storage capacity of 9.7 wt % at 300 °C, even after 10 cycles of hydrogen storage.