Hydrogen desorption performance of high-energy ball milled Mg2NiH4 catalyzed by multi-walled carbon nanotubes coupling with TiF3

• Mg2NiH4 can be synthetized by ball milling 2MgH2 with Ni in only one step.
• Desorption temperature of Mg2NiH4 reduces drastically with MWCNTs and TiF3.
• Dehydrogenation activation energies of catalyzed Mg2NiH4 are obtained.
• Catalytic dehydrogenation mechanism of MWCNTs/TiF3 on Mg2NiH4 is proposed.

The Mg2NiH4 complex hydrides were synthesized by high-energy ball milling (HEBM) MgH2 + Ni mixtures. Multi-walled carbon nanotubes (MWCNTs) or TiF3 as catalysts were added and the catalytic-dehydrogenation behaviors were investigated. All prepared samples are characterized by X-ray diffraction (XRD) spectroscopy, scanning electron microscope (SEM) and differential scanning calorimetry (DSC) to acquire information of microstructure, phase compositions, surface and dehydrogenation properties. The results indicate that the method of adding catalysts by HEBM is reasonable and the hydrogen desorption property of Mg2NiH4 is improved by catalysts. It is worth noting that the dehydrogenation temperature (TD) and the activation energy (Ea) of Mg2NiH4 catalyzed by MWCNTs coupling with TiF3 are reduced to 230 °C (243.6 °C of Mg2NiH4) and 53.24 kJ/mol (90.13 kJ/mol of Mg2NiH4), respectively. The addition of proper catalysts is proved to be an effective strategy to decrease TD and Ea of Mg2NiH4 hydrides.