Boron nitride supported nickel nanoparticles as catalyst for enhancing the hydrogen storage properties of MgH2

In this work, layered boron nitride nanosheets loaded with fine nickel particles were synthesized by a solution chemical reduction method and introduced into MgH2. The best catalytic activity in kinetics has been found in Ni70 @BN, the nickel particles of which are only 10–30 nm in size, showing homogenous dispersion state. Ni particles distributed on the surface of BN provided many active sites, which markedly improved the hydrogen storage properties of MgH2. The MgH2/Ni70 @BN composite absorbs 5.34 wt% H2 swiftly within 25 s at 125 °C and releases 6.21 wt% H2 in 15 min at 300 °C. The dehydrogenation activation energy is reduced to 59.77 ± 3.96 kJ/mol, which is significantly lower than that of pure MgH2 (145.08 kJ/mol). Moreover, BN acts as the aggregation preventer, thereby maintaining outstanding cycling performance of Ni70 @BN modified MgH2 even after 30 cycles. According to DFT calculations, the in-situ formed Mg2Ni is verified to reduce the barrier energy of (de)hydrogenation. Thus, the synergistic effect between BN and Mg2Ni(H4) facilitates the "hydrogen pump" effect to accelerate the ad/desorption kinetics of Mg/MgH2. This work will attract more attention to the synergistic effect of 0D and 2D structures and supplies a new insight into the design of multi-phase catalysts.