NaNH₂–NaBH₄ hydrogen storage composite materials synthesized via liquid phase ball-milling: Influence of Co–Ni–B catalyst on the dehydrogenation performances

The composite NaNH₂–NaBH₄ (2/1 molar rate) doped with different amount Co–Ni–B catalyst was synthesized via liquid phase ball-milling method in the cyclohexane agent. The composition evolution and dehydrogenation performance of the as-prepared sample were characterized by means of XRD (X-ray diffraction), FT-IR (Fourier transform infrared spectroscopy) and TG–DTA–MS (Thermogravimetric–differential thermal analysis–mass spectroscopy) measurements, respectively; and the activation energies were calculated by the Achar differential and Coats–Redfern integral method. The composite NaNH₂–NaBH₄ (2/1) with 5 wt% Co–Ni–B catalyst (the sample C5) generated Na₃(NH₂)₂BH₄ successfully after the liquid phase ball-milling. Due to the interaction between functional groups of NaNH₂–NaBH₄ (2/1) with catalyst, Co–Ni–B catalyst not only benefits improving the thermodynamical performance, that is, the initial dehydrogenation temperature is as low as 200 °C and the weight percentage of hydrogen is about 5.05 wt% obtained from TG–DTA-MS curves; but also promoting the kinetics property that the activation energy of the major dehydrogenation stage is only 68.2 kJ mol⁻¹. Furthermore, it is revealed that the kinetics mechanism of the dehydrogenation performance depends on the synthesis methods and adding catalyst.