Efficient hydrogen storage remains a critical challenge for the large-scale utilization of hydrogen as a sustainable energy carrier. In this study, we present a novel boron nitride (BN)-sewn magnesium (Mg) nanocomposite that demonstrated high-density hydrogen storage with fast release kinetics. The Mg nanoparticles (Mg NPs) were stabilized within an oxidation-resistant BN matrix through a two-step process: first, partial unzipping of hexagonal boron nitride (h-BN), followed by the chemical incorporation of Mg NPs into the unzipped sites. Detailed structural characterization, complemented by theoretical calculations, confirmed the integrity and effectiveness of this strategy. Additionally, we demonstrated how oxidative dehydrogenation of propane (ODHP) generates oxygen-functionalized BN sites, which anchor the Mg NPs, inhibit oxidation, and enhance surface reactivity. The resultant Mg-BN nanocomposite exhibited a hydrogen storage capacity of 6.92 wt.% (0.128 kg H₂/L) at 200 °C and 35 bar, with a desorption activation energy of 46.2 kJ/mol, significantly lower than bulk MgH₂. This enabled rapid hydrogen release and excellent stability over five charge-discharge cycles. Our work introduces the "partial unzipping followed by chemical sewing" approach as a scalable and effective method for developing high-performance Mg-based hydrogen storage materials.
