▎ 摘　　要

NOVELTY - Composition of matter comprises reduced graphene oxide-magnesium nanocrystals nanolaminates. USE - The composition of matter is useful: for hydrogen storage; and in batteries, catalysis, encapsulants and energetic materials. ADVANTAGE - The composition of matter: is environmentally stable; allows for safe, stable and selective hydrogen storage; exhibits exceptionally dense hydrogen storage (6.5 wt.% and 0.105 kg hydrogen/l in the total composite, 7.56 wt.% in magnesium), hence capable of delivering exceptionally dense hydrogen storage far-exceeding 2020 Department of Energy (DOE) target metrics for gravimetric capacity (5.5 wt%), and ultimate full-fleet volumetric targets (0.07 kg hydrogen/l) for fuel cell electric vehicles; exhibits decreased water permeability while maintaining desirable gas permeability characteristics; utilizes reduced graphene oxide that minimizes added mass, catalytically enhances rate-limiting hydrogen absorption/desorption events, and provides protective barrier to prevent degradation of magnesium nanocrystals; exhibits faster hydrogen absorption/desorption than magnesium-polymer composites containing nanocrystals of similar size; and has excellent reversibility The nanoscale size of the magnesium crystals is comparable to molecular diffusion lengths, which enables near complete conversion to the metal hydride (99.5% of the theoretical value), and the interaction of the magnesium nanocrystals with the reduced graphene oxide layers protects against invasion of oxygen while enabling rapid surface diffusion of hydrogen, which enhances kinetics. The reduced graphene oxide exhibits high Young's modulus to robustly encase the magnesium nanocrystals during expansion/contraction events without fracture and prevent macroscale sintering. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for preparing reduced graphene oxide-magnesium nanocrystal nanolaminates, comprising ball-milling graphene oxide to break down the graphene oxide to graphene oxide platelets in order to complex with bis(cyclopentadienyl) magnesium, preparing a lithium naphthalenide solution by dissolving naphthalene in tetrahydrofuran (THF), followed by the immediate addition of lithium metal to produce the lithium naphthalenide solution, dispersing graphene oxide in the THF to form a graphene oxide solution, adding the bis(cyclopentadienyl) magnesium solution to the graphene oxide solution to produce a graphene oxide/bis(cyclopentadienyl) magnesium solution, adding the graphene oxide/bis(cyclopentadienyl) magnesium solution to the lithium naphthalenide solution to produce the reduced graphene oxide-magnesium nanocrystal nanolaminates, and centrifuging and washing the reduced graphene oxide-magnesium nanocrystal nanolaminates with THF followed by drying.