Room temperature conversion of Mg to MgH2 assisted by low fractions of additives

In recent works, it was noticed that Mg/MgH₂ mixed with additives by high energy ball milling allows temperature reductions of H₂ absorption/desorption without necessarily changing thermodynamic properties. Thus, the objective of this work was to investigate which additives, mixed in low fractions with MgH₂ powder would act as efficient hydrogen absorption/desorption catalysts at low temperatures, mainly at room temperature (RT). MgH₂ mixtures with 2 mol% additives (Fe, Nb₂O₅, TiAl and TiFe) were prepared by high energy reactive ball milling (RM). MgH₂–TiFe mixture showed the best results, both during desorption at 330 °C and absorption at RT. The hydrogen absorption was ≈ 2.67 wt% H₂ in 1 h and ≈ 4.44 wt% H₂ in 16 h (40% and 67% of maximum theoretical capacity, respectively). The MgH₂–TiFe superior performance was attributed to the hydrogen attraction by the created high energy interfaces and strong TiFe catalytic action facilitating the H₂ flow during Mg/MgH₂ reactions.