Improved dehydrogenation of LiAlH4 by hollow 3D flower-like bimetallic composites M-NC@TiO2 (M=Ni, Co, Fe, Cu)

The sluggish kinetics and thermodynamic stability associated with LiAlH4 have posed significant obstacles to its practical application. Herein, we have designed a general method for preparing a series of hollow 3D flower-like composite, denoted as M-NC@TiO2 (M = Ni, Co, Fe, Cu), which serve as highly efficient catalysts for the dehydrogenation of LiAlH4. These composites feature TiO2 hollow spheres as substrates to induce the growth of MOF nanosheets, leading to the regular arrangement of carbon nanosheets anchored with metal nanoparticles M on the TiO2 sphere surface after calcination treatment. Evidently, M-NC@TiO2 exerts a discernible enhancement on the dehydrogenation kinetics of LiAlH4. LiAlH4-7wt% Ni-NC@TiO2 system begins to release hydrogen at a notably lowered temperature of 56.3 °C, with a total amount of hydrogen released of 7.19 wt% before reaching 300 °C. Subsequent investigations showed that the enhanced hydrogen storage performance can be attributable to the in-situ formation of the metal compounds, the fine size and high dispersion of metallic nanoparticles, and the synergistic effect between TiO2 and M nanoparticles. This work not only provides an effective general way to synthesize catalysts for improving the hydrogen storage performance of aluminum-based hydrogen storage materials, but also augments our understanding of hydrogen storage mechanisms.