▎ 摘　　要

NOVELTY - Nanostructured composite comprises sheets or layers of graphene derivatives or graphene nanoribbons and many metal nanocrystals located between and in contact with the sheets or layers of the graphene derivatives. The nanostructured composite is capable of reversibly adsorbing at least one gas. USE - The nanostructured composite is useful: in a gas storage device, which is used with a fuel cell and/or an internal combustion engine of a vehicle; in a gas separation device, which is a membrane-based separation device; to separate and/or store hydrogen gas; and in a catalytic, carbon dioxide reduction or water splitting method (all claimed). ADVANTAGE - The nanostructured composite: is able to store and deliver hydrogen gas at a gravimetric capacity which exceeds 5.5 wt.%, preferably at 6.38 wt.% of the nanostructured composite (claimed); and utilizes graphene derivatives that provides selective permeability and kinetic enhancement of gases. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: (1) a method (M1) to separate and/or store hydrogen gas, comprising contacting the nanostructured composite with hydrogen gas or a gas mixture comprising hydrogen gas; and (2) a method (M2) to fabricate the nanostructured composites, comprising adding a mixture comprising ball-milled graphene oxide, bis(cyclopentadienyl)magnesium, and a first solvent to a solution comprising a reducing agent and a second solvent, where the first and second solvent may or may not be the same solvent.