Enhancing Reversible Hydrogen Storage Performance of LiBH₄ Catalyzed by N-Doped Carbon Nanosheet Networks Embedded with Co Nanoparticles

LiBH₄ 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 LiBH₄. Co NPs and the <i>in situ</i> formed CoB in Co/N-CNSNs during the initial hydrogen desorption process could catalytically weaken the B-H bonds in LiBH₄, resulting in the reduction of H dissociation energy to 0.34 and 0.31 eV, respectively, much lower than that of pure LiBH₄ (1.95 eV). Benefiting from the synergistic effect of the catalytic role of Co NPs and the <i>in situ</i> formed CoB and the nanoconfinement role of Co/N-CNSNs, 10.1 wt % hydrogen could be released from LiBH₄@Co/N-CNSNs at 300 °C within 180 min, while this value is decreased to only 1.5 wt % for bulk LiBH₄ under the identical condition. Moreover, the homogeneous molecular interaction between Co/N-CNSNs and LiBH₄ 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 LiBH₄, contributing to improving its reversibility. Hence, LiBH₄ 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.