Abstract: By ball milling carbon nitride (C₃N₄) and ammonia borane (AB), the AB-C₃N₄ system was successfully synthesized. It is shown that the dehydrogenation temperature of the AB-C₃N₄ system was obviously decreased. However, the concentration of byproduct ammonia was much higher than that of pristine AB. Thus, LiBH₄-modified C₃N₄ (LC₃N₄) was produced and employed to synthesize a AB-LC₃N₄ system. The dehydrogenation of the AB-LC₃N₄ system was investigated using X-ray diffraction, temperature-programmed desorption-mass spectrometry, thermogravimetry-differential thermal analysis, and nuclear magnetic resonance. The results show that the dehydrogenation temperatures of the AB-LC₃N₄ systems were reduced to a lower region compared with pristine AB. Moreover, byproduct borazine and the induction period were significantly suppressed. After LiBH₄ modification on C₃N₄, the other byproduct ammonia was also reduced in the dehydrogenation process. Dynamic analysis and NMR characterization results show that the decomposition mechanism of AB-LC₃N₄ still follows the self-decomposition of AB, which is induced by the formation of NH₃BH₂NH₃BH₄.

Key words: Ammonia borane, Carbon nitride, Dehydrogenation, Lithium borohydride