Dual-phase nanoconfinement effects: Vanadium-MOF derived nanoporous carbon-coated V2O3 nanorods as multifunctional additives for advanced Mg-based hydrogen storage

Due to their large specific surface area and high porosity, porous carbon materials have emerged as a prominent research focus in the field of hydrogen storage. In this study, nanoporous carbon-coated V 2 O 3 nanorods (p-V 2 O 3 /C) were synthesized through high-temperature calcination under a gas mixture using a vanadium metal-organic framework (V-MOF) as a precursor, aimed at enhancing the hydrogen storage performance of MgH 2 . The incorporation of p-V 2 O 3 /C significantly reduced both the initial dehydrogenation temperature and the activation energy for dehydrogenation of MgH 2 to 192 °C and 88.6 kJ∙mol −1 , respectively. Notably, catalytic MgH 2 can desorb 5.35 wt% hydrogen even at a low temperature of 225 °C over a duration of 75 min, with an impressive capacity retention rate of 98.5% after 30 cycles of hydrogen absorption/release. The proposed catalytic mechanism indicates that the presence of metals such as V, VO, V 2 O 3 , and MgO in the composite system formed by p-V 2 O 3 /C with ball-milled MgH 2 serves to reduce the Mg-H bond strength, thereby facilitating easier dehydrogenation of MgH 2 . Additionally, incorporating MgO can stabilize the crystal interface of MgH 2 while impeding particle growth and enhancing its dehydrogenation process. In this work, the multiphase composite system based on p-V 2 O 3 /C has improved the kinetic performance for hydrogen storage in MgH 2 .