Ni-Doped Pd/TiO ₂ as a High-Efficiency Nanocatalyst for Hydrogen Storage of Magnesium Hydride

Magnesium hydride is regarded as a promising candidate for hydrogen storage and transportation owing to its substantial hydrogen capacity, affordability, and ecological compatibility. Nevertheless, its practical application is constrained by a relatively high operating temperature and unsatisfactory hydrogen absorption/desorption kinetics. Herein, a Ni-doped Pd/TiO 2 nanocatalyst was successfully synthesized, and its effective catalysis on enhancing the hydrogen storage performance of MgH 2 was systematically studied via combined experimental and density functional theory (DFT) approaches. At 275 °C, the MgH 2 –NiPd/TiO 2 composite desorbs 6.09 wt % H 2 within 1800 s, significantly higher than that of MgH 2 –Pd/TiO 2 (5.41 wt %) and as-milled MgH 2 (0.1 wt %) under the same conditions. Moreover, NiPd/TiO 2 helps to decrease the dehydrogenation activation energy from 153 to 71.60 kJ/mol. MgH 2 –NiPd/TiO 2 also shows an excellent cyclic stability with an average attenuation rate of less than 1% for each cycle. The DFT calculations also confirm that metal atoms more easily interact with hydrogen atoms than TiO 2 . The adsorption energy of hydrogen is 0.781 eV for TiO 2, which is reduced to −0.938 eV for Pd/TiO 2, and it further reduces to −1.227 eV for NiPd/TiO 2 . Electronic structure simulations suggest that the narrower the band gap, the more easily hydrogen diffuses. This work demonstrates that nano-NiPd/TiO 2 effectively promoted the dehydrogenation of MgH 2 .