Nanoscale microstructure and hydrogen storage performance of as cast La-containing V-based multicomponent alloys.

Vanadium-based alloys (VBAs) occupy a prominent position in the field of hydrogen storage materials due to their many advantages, including the ability to absorb/desorb hydrogen with high capacity under moderate conditions. However, the kinetic and thermodynamic properties of these alloys must be improved to expand the range of their practical applications. In this work, we systematically studied the influence of La doping on the microstructure and hydrogen storage performance of multicomponent VBAs. It was found that the as-cast multicomponent V 48 Fe 12 Ti 30 Cr 10 alloy prepared by arc melting contained micrometer/nanometer-sized crystals, which differed from the microstructure of traditional coarse-grained VBAs fabricated in the past decades. After the alloy was doped with La metal, its grains were refined into nanocrystallites with remarkable hydrogen absorption properties. This indicates that nanostructured VBAs can be realized by casting techniques, which is a traditional, low-cost, and engineering approach. The hydrogen storage capacity of the alloys first increased and then decreased with increasing La content. Furthermore, La doping considerably increased the alloy cycling stability. These findings can be used to develop novel hydrogen absorption materials for fuel cells with superior kinetic and thermodynamic properties. [Display omitted] • A multicomponent V-based alloy has a micron/nano-scale coexisted microstructure. • Doping La facilitates alloy grain refinement. • La-doped alloys exhibit excellent hydrogenation kinetics. • The phase transformation during dehydrogenation were studied in detail. • Doping La significantly improves the cycling stability of V-based alloys. [ABSTRACT FROM AUTHOR]