Abstract: Herein, a novel TiO₂/CN heterojunction material has been prepared by one-step bubble template-assisted calcination to enhance the hydrogen storage capability of LiAlH₄. The TEM, XPS and UPS analysis confirm that a heterostructure is formed between TiO₂ and g-C₃N₄ successfully. The experimental findings indicate that the TiO₂/CN significantly enhances the dehydrogenation performance of LiAlH₄. For instance, the LiAlH₄-7 wt% TiO₂/CN starts to dehydrogenize at 76 °C (94 °C less than pure LiAlH₄) and releases 6.5 wt% H₂ at 200 °C. Meanwhile, LiAlH₄-7 wt% TiO₂/CN releases 4.9 wt% H₂ at 120 °C within 50 min. The mechanism analysis illustrates that AlTi₃N is formed in situ during ball-milling. And density functional theory (DFT) calculation results reveal that the AlTi₃N can weaken the Al-H bonds in LiAlH₄ through interfacial charge transfer. Furthermore, the TiO₂/CN heterostructure creates an internal electric field that generates an electron-rich layer. As a result, the negative electron layer at one end of the TiO₂/CN heterojunction has an increased affinity for H, which enhances the dehydrogenation reaction of LiAlH₄. Clearly, both the TiO₂/CN heterostructure and AlTi₃N contribute to the improvement of the dehydrogenation properties of LiAlH₄.

Key words: Hydrogen storage material, LiAlH₄, TiO₂, Carbon nitride, Heterojunction