Interfacial engineering of nickel/vanadium based two-dimensional layered double hydroxide for solid-state hydrogen storage in MgH2

As a high-density solid-state hydrogen storage material, magnesium hydride (MgH 2 ) is promising for hydrogen transportation and storage. Yet, its stable thermodynamics and sluggish kinetics are unfavorable for that required for commercial application. Herein, nickel/vanadium trioxide (Ni/V 2 O 3 ) nanoparticles with heterostructures were successfully prepared via hydrogenating the NiV-based two-dimensional layered double hydroxide (NiV-LDH). MgH 2 + 7 wt% Ni/V 2 O 3 presented more superior hydrogen absorption and desorption performances than pure MgH 2 and MgH 2 + 7 wt% NiV-LDH. The initial discharging temperature of MgH 2 was significantly reduced to 190 °C after adding 7 wt% Ni/V 2 O 3 , which was 22 and 128 °C lower than that of 7 wt% NiV-LDH modified MgH 2 and additive-free MgH 2 , respectively. The completely dehydrogenated MgH 2 + 7 wt% Ni/V 2 O 3 charged 5.25 wt% H 2 in 20 min at 125 °C, while the hydrogen absorption capacity of pure MgH 2 only amounted to 4.82 wt% H 2 at a higher temperature of 200 °C for a longer time of 60 min. Moreover, compared with MgH 2 + 7 wt% NiV-LDH, MgH 2 + 7 wt% Ni/V 2 O 3 shows better cycling performance. The microstructure analysis indicated the heterostructural Ni/V 2 O 3 nanoparticles were uniformly distributed. Mg 2 Ni/Mg 2 NiH 4 and metallic V were formed in-situ during cycling, which synergistically tuned the hydrogen storage process in MgH 2 . Our work presents a facile interfacial engineering method to enhance the catalytic activity by constructing a heterostructure, which may provide the mentality of designing efficient catalysts for hydrogen storage.