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

Abstract

As a high-density solid-state hydrogen storage material, magnesium hydride (MgH2) 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/V2O3) nanoparticles with heterostructures were successfully prepared via hydrogenating the NiV-based two-dimensional layered double hydroxide (NiV-LDH). MgH2 + 7 wt% Ni/V2O3 presented more superior hydrogen absorption and desorption performances than pure MgH2 and MgH2 + 7 wt% NiV-LDH. The initial discharging temperature of MgH2 was significantly reduced to 190 °C after adding 7 wt% Ni/V2O3, which was 22 and 128 °C lower than that of 7 wt% NiV-LDH modified MgH2 and additive-free MgH2, respectively. The completely dehydrogenated MgH2 + 7 wt% Ni/V2O3 charged 5.25 wt% H2 in 20 min at 125 °C, while the hydrogen absorption capacity of pure MgH2 only amounted to 4.82 wt% H2 at a higher temperature of 200 °C for a longer time of 60 min. Moreover, compared with MgH2 + 7 wt% NiV-LDH, MgH2 + 7 wt% Ni/V2O3 shows better cycling performance. The microstructure analysis indicated the heterostructural Ni/V2O3 nanoparticles were uniformly distributed. Mg2Ni/Mg2NiH4 and metallic V were formed in-situ during cycling, which synergistically tuned the hydrogen storage process in MgH2. 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.