Bimetallic NiCo Functional Graphene: An Efficient Catalyst for Hydrogen‐Storage Properties of MgH₂

Abstract

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.

Catalytic effects of different Ti-based materials on dehydrogenation performances of MgH2

“…1(a), both pure MgH 2 and MgH 2 -TiO 2 sample showed two obvious peaks, different from other composites. This may due to the bimodal particle size distribution [4,18] and/or the decomposition of MgH 2 -TiO 2 was a two-step process. The detailed reason for this phenomenon was discussed in the following text.…”

Monodisperse Magnesium Hydride Nanoparticles Uniformly Self‐Assembled on Graphene

“…Graphene (GR), a 2D single‐atomic‐layer sheet, is an exceedingly desirable candidate to host active NPs because of its unique 2D nanostructure, light weight, excellent thermal conductivity, and high chemical stability . It is believed that the ultrathin, flexible GR with its catalytic action toward hydrogen dissociation/recombination could not only serve as a support for anchoring well‐dispersed NPs and various catalysts for further improvement, but also effectively prevent the aggregation and growth of Mg‐based hydrides during de‐/rehydrogenation . Additionally, it is well known that the reversible hydrogen storage process in Mg‐based hydrides involves exo‐/endothermic reactions for hydrogenation and dehydrogenation, which necessitates rapid heat transfer in order to meet the criteria of fast refueling for its application.…”

Improvement of Mg‐Based Hydrogen Storage Materials by Metal Catalysts: Review and Summary

“…The faster dehydrogenation speed may be related to the higher hardness and more uniform distribution of alloying elements of the melt spinning alloy powder. Wang et al [55] synthesized NiCo functional graphene by hydrothermal method. NiCo nanoparticles (NPs) were uniformly anchored to the reduced rGO.…”