Layered double hydroxide-derived Mg₂Ni/TiH_1.5 composite catalysts for enhancing hydrogen storage performance of MgH₂

Developing efficient catalysts is of great significance in improving the sluggish kinetics and high desorption temperature of MgH₂ hydrogen storage material. Here, ultrathin NiTi-layered double hydroxide (NiTi-LDH) nanosheets are used as precursors to prepare Mg₂Ni/TiH_1.5 composite catalysts to improve the hydrogen storage properties of MgH₂. The variation of Ni/Ti ratio in LDH plays an important role in regulating the composition, morphology and distribution of Mg₂Ni/TiH_1.5 catalysts, which significantly affect their synergistic catalytic effect. Mg₂Ni/TiH_1.5 composite catalyst exhibits significantly improved catalytic performance compared with conventional Ni-, Ti- and Ni/Ti-based catalysts. The optimal MgH₂/Mg₂Ni/TiH_1.5 system shows a significantly reduced desorption temperature of 212 ℃ which is 133 ℃ lower than that of pure MgH₂ (345 ℃), and can release 5.97 wt% hydrogen within 300s at 300 ℃. Further mechanism analysis reveals that the unique flaky morphology and suitable composition of Ni/Ti LDH can significantly enhance the synergistic effect of Mg₂Ni and TiH_1.5, which promotes the fracture of the HH and Mg-H bonds.