Improvement in hydrogen storage performance of MgH₂ by vanadium doped with ZIF-8 derived a single-atom catalyst V–N–C

Herein, the successful preparation of a single-atom catalyst V–N–C using vanadium-doped zeolitic imidazolate framework (ZIF)-8 as a precursor is reported. The experimental results showed that the V–N–C had a good promoting effect on the hydrogen storage performance of MgH₂, and the optimal addition amount of V–N–C was 10 wt%. The hydrogenation and dehydrogenation apparent activation energies of 10 wt% V–N–C-catalyzed MgH₂ were reduced by 44.9 and 53.5 kJ·mol⁻¹, respectively, compared to those of additive-free MgH₂. The 10 wt% V–N–C-catalyzed MgH₂ could reabsorb 5.92 wt% of hydrogen in 50 min at 150 °C, with a capacity retention rate of 99.1% after 30 cycles of hydrogen absorption and desorption. Mechanism analysis showed that V–N–C was partially transformed into VN and metallic V when it was milled with MgH₂; the in-situ-formed VN and metallic V played an important role in improving the hydrogen storage performance of MgH₂. This approach provides a potential solution for obtaining high-performance Mg-based hydrogen storage materials through synergistic interactions between V, N and C.