Excellent catalytic activity of in-situ formed TiC nanoparticles for boosting hydrogen release from light metal hydride.

Lithium aluminum hydride (LiAlH) exhibits significant potential as a solid-state hydrogen storage medium. However, its practical implementation is restricted by high activation barriers, kinetic limitations, and irreversibility. In this work, a novel solvent-induced phase separation strategy was employed to synthesize TiC@C with excellent catalytic activity, aiming to improve the dehydrogenation performance of LiAlH. The addition of 5 wt% TiC@C remarkably reduces the initial hydrogen desorption temperature of LiAlH by 124 °C, decreasing from 164 °C to 40 °C. The composite system achieves rapid hydrogen release with 4.5 wt% H liberated within 2 h at 90 °C and 6.2 wt% H desorbed in merely 20 min at 150 °C. Kinetic analysis indicates significantly reduced activation energies for both dehydrogenation stages, decreasing from 136.5 kJ/mol to 71.6 kJ/mol for the first stage and from 123.6 kJ/mol to 94.2 kJ/mol for the second stage. Multiscale characterizations combining kinetic analysis reveal that the exceptional performance originates from ball milling-induced in-situ formation of TiC phase, which generates numerous favorable nucleation sites for dehydrogenation products. These interfacial structures create abundant heterointerfaces with LiAlH. Density functional theory (DFT) calculations reveal that, in different structural states, TiC@C facilitates AlH bond elongation through orbital dehybridization and interfacial electron transfer via Al → Ti charge polarization, thereby significantly lowering the AlH bond dissociation energy barrier in the composite system. These effects change the two-step dehydrogenation models of LiAlH, making it easier for hydrogen release and uptake. This interfacial catalysis paradigm establishes new fundamental principles for overcoming kinetic limitations in metal hydride-based hydrogen storage systems through targeted electronic and crystallographic engineering.