Effects of alloying elements (Al, Mn, Ru) on desorption plateau pressures of vanadium hydrides: An experimental and first-principles study

Vanadium-based alloys are promising for the reversible and compact storage of renewable hydrogen. To improve the hydrogen desorption plateau pressure of vanadium hydrides, V–3A binary alloys of V97Al3, V97Mn3, and V97Ru3 were prepared by vacuum arc melting. Hydrogen absorption and desorption properties of the newly prepared V–3A alloys were studied, and compared to vanadium hydrides, by pressure-composition-temperature measurements and first-principles calculations. Among the studied materials, V–3Ru showed the highest hydrogen desorption plateau pressures between T = 373 and 433 K. During hydrogen loading, V–3Ru also reached the highest hydrogen to metal ratio between the alloys. Meanwhile, V–3Ru was also the alloy with the highest hardness. Findings of hydrogen absorption and desorption measurements were supported with DFT calculations of hydride formation energies. The calculated DOS, ELF and atomic charges were used to study the effects of alloying on the electronic properties of hydrides. The bonding interactions in vanadium dihydrides were influenced the most through Al alloying, whereas V–3Mn and V–3Ru hydrides showed comparable electronic properties.