Light-weight NaNH₂-NaBH₄ hydrogen storage material synthesized via liquid phase ball milling

As a light-weight and low-cost hydrogen storage composite, NaNH ₂-NaBH₄ (molar ratio of 2:1) was prepared by a liquid phase ball milling (LPBM) method under the co-protection of argon and cyclohexane. The structure evolution and the thermal decomposition performance of the as-prepared sample were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermo gravimetric-differential thermal analysis (TG-DTA), respectively. It is found that the interaction of NaNH₂ with NaBH₄ is enhanced by LPBM, thus causes a preferred orientation for the crystal structure of NaNH₂, and the red-shifts of the N-H stretching vibration and the B-H stretching vibration. In addition, the as-prepared NaNH₂-NaBH₄ (2/1) can achieve a low activation energy of 76.4 kJ mol^-1 during the main decomposition stage, which is only 47.9% of that of the one synthesized via a solid state ball milling (SSBM) method, and is very close to that of the Co-B catalyst promoted one. This indicates the LPBM method is an efficient way to get high-performance NaNH₂-NaBH₄, whose thermal decomposition kinetics can be greatly improved without any catalyst.