Reversible solid-state hydrogen storage of magnesium hydride, traditionally driven by external heating, is constrained by massive energy input and low systematic energy density. Herein, a single phase of Mg₂Ni(Cu) alloy is designed via atomic reconstruction to achieve the ideal integration of photothermal and catalytic effects for stable solar-driven hydrogen storage of MgH₂. With the intra/inter-band transitions of Mg₂Ni(Cu) and its hydrogenated state, over 85% absorption in the entire spectrum is achieved, resulting in the temperature up to 261.8 °C under 2.6 W cm⁻². Moreover, the hydrogen storage reaction of Mg₂Ni(Cu) is thermodynamically and kinetically favored, and the imbalanced distribution of the light-induced hot electrons within CuNi and Mg₂Ni(Cu) facilitates the weakening of Mg-H bonds of MgH₂, enhancing the “hydrogen pump” effect of Mg₂Ni(Cu)/Mg₂Ni(Cu)H₄. The reversible generation of Mg₂Ni(Cu) upon repeated dehydrogenation process enables the continuous integration of photothermal and catalytic roles stably, ensuring the direct action of localized heat on the catalytic sites without any heat loss, thereby achieving a 6.1 wt.% H₂ reversible capacity with 95% retention under 3.5 W cm⁻².

Porous Ni nanofibers (NFs) were synthesized via a single-nozzle electrospinning technique with subsequent calcination and reduction. The as-prepared continuous Ni NFs, with a uniform diameter of ∼50 nm and porous structure composed of a myriad of Ni nanocrystallites, were adopted to catalyze MgH₂. The homogeneous distribution of Ni nanoparticles (NPs), obtained by ball milling Ni NFs with MgH₂, on the surface of MgH₂ offered effective catalytic sites to significantly enhance the hydrogen storage properties of MgH₂. In particular, 4% Ni NF catalyzed MgH₂ (MgH₂–4% Ni NFs) starts to release hydrogen at only 143 °C, with a peak temperature of 244 °C, 157 °C and 96 °C lower than for MgH₂ catalyzed with as-milled 4% Ni powders (MgH₂–4% Ni powders), and it dehydrogenates completely within only 11 min at 325 °C (7.02 wt%). Compared with plain MgH₂ and MgH₂–4% Ni powders, the activation energy of the as-milled MgH₂–4% Ni NF composite is significantly decreased to 81.5 kJ mol⁻¹.