Intrinsic mechanisms of superior hydrogen storage properties in V–Fe–Ti alloys: A combined experimental and theoretical study

Vanadium-based alloys have excellent reversible hydrogen storage properties, and the empirical lattice parameter law is often used experimentally for optimization of alloy composition. To reveal the underlying mechanisms, hydrogen storage properties and local environmental effect of H dissolution in V–Fe–Ti alloys were studied experimentally and computationally. The experimental results show that adding Fe and Ti has opposite effects on the hydrogen storage capacity of alloys, and (V85Fe15)100-xTix alloys with 20%Ti addition can exhibit the best performance, which satisfies the empirical lattice parameter law. Furthermore, atomic-scale simulations have demonstrated that H dissolution is affected by its dissolution location and surrounding alloy species through comparing the stability, electronic structure, and bonding characteristics of different V-based alloys. Besides, the correlation analyses of different factors with the hydrogen dissolution energy verify the rationality of the empirical law. Our findings provide useful insight into the rational design of Fe–V–Ti alloys for high-capacity hydrogen storage.