Non-isothermal synergetic catalytic effect of TiF₃ and Nb₂O₅ on dehydrogenation high-energy ball milled MgH₂

MgH₂-M (M = TiF₃ or Nb₂O₅ or both of them) composites prepared by high-energy ball milling are used in this work to illustrate the dehydrogenation behavior of MgH₂ with the addition of catalysts. The phase compositions, microstructures, particle morphologies and distributions of MgH₂ with catalysts have been evaluated. The non-isothermal synergetic catalytic-dehydrogenation effect of TiF₃ and Nb₂O₅ evaluated by differential scanning calorimetry gives the evidences that the addition of catalysts is an effective strategy to destabilize MgH₂ and reduce hydrogen desorption temperatures and activation energies. Depending on additives, the desorption peak temperatures of catalyzed MgH₂ reduce from 417 °C to 341 °C for TiF₃ and from 417 °C to 336 °C for Nb₂O₅, respectively. The desorption peak temperature reaches as low as 310 °C for MgH₂ catalyzed by TiF₃ coupling with Nb₂O₅. The non-isothermal synergetic catalytic effect of TiF₃ and Nb₂O₅ is mainly attributed to electronic exchange reactions with hydrogen molecules, which improve the recombination of hydrogen atoms during dehydrogenation process of MgH₂.