Bimetallic NiCo functional graphene: an efficient catalyst for hydrogen-storage properties of MgH₂.

Bimetallic NiCo functional graphene (NiCo/rGO) was synthesized by a facile one-pot method. During the coreduction process, the as-synthesized ultrafine NiCo nanoparticles (NPs), with a typical size of 4-6 nm, were uniformly anchored onto the surface of reduced graphene oxide (rGO). The NiCo bimetal-supported graphene was found to be more efficient than their single metals. Synergetic catalysis of NiCo NPs and rGO was confirmed, which can significantly improve the hydrogen-storage properties of MgH2. The apparent activation energy (E(a)) of the MgH2-NiCo/rGO sample decreases to 105 kJ mol(-1), which is 40.7% lower than that of pure MgH2. More importantly, the as-prepared MgH2-NiCo/rGO sample can absorb 5.5 and 6.1 wt% hydrogen within 100 and 350 s, respectively, at 300 °C under 0.9 MPa H2 pressure. Further cyclic kinetics investigation indicates that MgH2-NiCo/rGO nanocomposites have excellent cycle stability.