Solar-Driven Reversible Hydrogen Storage Over LiNH2-2LiH.

Lithium amide-lithium hydride composite (LiNH2-2LiH), a composite hydride with a high hydrogen capacity of 10.29 wt.%, has long been considered a promising candidate for hydrogen storage; however, its application is hindered by the thermodynamic stability and sluggish kinetics associated with N─H and Li─H bond cleavage and formation during thermally driven de/re-hydrogenation. Herein, we report that the photoexcitation of LiNH2 under UV illumination (0.8 W·cm-2) induces homolytic N─H bond cleavage and produces a distinctive photo-response with simultaneous evolution of H2, N2, and NH3. Coupling LiNH2 with LiH enables UV-driven hydrogen release with effective suppression of gaseous byproducts. Under high-intensity full-spectrum illumination (2.9  W·cm-2), the combined non-thermal and photothermal effects allow complete dehydrogenation of LiNH2-2LiH (>10.0 wt.%), and near-full reversibility over 6 cycles (capacity retention ca. 99%). We further realized direct hydrogen release from LiNH2-2LiH under natural sunlight. This photo-induced destabilization strategy provides a general route to activate strong bonds in amide-hydride composites and offers a promising approach toward solid-state hydrogen storage under mild conditions.