Improved dehydrogenation properties of AlH₃ catalysed with Ni powder

This study shows that nickel (Ni) doping dramatically improves AlH₃'s dehydrogenation properties for solid-state hydrogen storage material. While pure AlH₃ releases hydrogen at 146 °C, ball milling lowers this to 120 °C, and 10 wt% Ni doping achieves an even more significant reduction to 80 °C while maintaining 9.2 wt% capacity. At 90 °C, the Ni-doped sample releases ∼7.0 wt% hydrogen in 20 min—a significant improvement compared to milled AlH₃, which released only 1 wt% hydrogen within the same condition. The Kissinger analysis calculation based on the differential scanning calorimetry confirms the reduction in activation energy for hydrogen release from Ni-doped AlH₃ (75.9 kJ/mol) compared to undoped AlH₃ (115.9 kJ/mol). The scanning electron microscopy reveals Ni doping enhances particle dispersion and reduces particle size, while X-ray diffraction spectra verify Ni acts catalytically without chemical reaction with AlH₃. These improvements stem from Ni's ability to create active sites, shorten diffusion paths, and weaken Al–H bonds through charge transfer effects. Apart from its irreversibility, the combined benefits of lower operating temperature, faster kinetics, and retained capacity position Ni-doped AlH₃ as an excellent candidate for practical hydrogen storage applications.