Regulation of nanoscale Mg/V incoherent interface interactions to enhance hydrogen storage properties in Mg/V multilayer films

Magnesium-based materials offer a promising, cost-effective, and high-capacity solution for hydrogen storage. However, their slow kinetics and elevated absorption/desorption temperatures limit their large-scale application. In this study, a series of Mg _1-x/V _x ( x = 0.05, 0.10, 0.15, 0.20) multilayer films were designed and fabricated using an ultra-high vacuum magnetron sputtering technique. Transmission electron microscopy (TEM) analysis revealed the presence of a discontinuous nanoscale V single-phase interlayer between the Mg layers, confirming the successful formation of Mg/V multilayer films. The surface of the deposited films predominantly consists of hexagonal particles of varying sizes stacked upon one another. Upon hydrogenation, tetragonal rutile structures of MgH ₂ and V ₂H were formed. The Mg _0.95V _0.05 film absorbed 6.40 wt% hydrogen within 15 min at 150 °C and desorbed 0.34 wt% hydrogen within 1.8 h at the same temperature, with an initial dehydrogenation temperature of 79 °C. The activation energies for hydrogen absorption and desorption were estimated to be 60 ± 7 and 140 ± 10 kJ/mol H ₂, respectively, significantly lower than the corresponding values of 100 and 160 kJ/mol H ₂ for conventional pure Mg/MgH ₂. The enhanced hydrogen absorption performance was attributed to the catalytic effect of nanocrystalline V at the Mg/V incoherent interface, while the improved desorption performance was due to the synergistic catalytic effect of nanocrystalline V ₂H at the MgH ₂/V ₂H incoherent interface. DFT calculations indicated that the interaction at the Mg/V incoherent interface promoted H atom adsorption and diffusion, significantly enhancing the hydrogenation and dehydrogenation performance of the multilayer films.