Solar‐Driven Reversible Hydrogen Storage Over LiNH ₂ ‐2LiH

Abstract

ABSTRACT Lithium amide‐lithium hydride composite (LiNH 2 ‐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 LiNH 2 under UV illumination (0.8 W·cm −2 ) induces homolytic N─H bond cleavage and produces a distinctive photo‐response with simultaneous evolution of H 2 , N 2 , and NH 3 . Coupling LiNH 2 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 LiNH 2 ‐2LiH (>10.0 wt.%), and near‐full reversibility over 6 cycles (capacity retention ca. 99%). We further realized direct hydrogen release from LiNH 2 ‐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.