Multivalent cation crosslinking suppresses highly energetic graphene oxide’s flammability

Graphene oxide (GO), a common intermediate for making graphene-like materials from graphite, was recently found to possess an explosive fire-hazard that can jeopardize the GO’s large-scale production and wide applications. This work reports a simple and facile method to cross-link the GO with Al³⁺ cations, in one step, into a freestanding flexible membrane. This inorganic membrane resists in-air burning on an open-flame, at which non-cross-linked GO was burnt out within ~5 seconds. All characterization data suggested that the in-situ “epoxy ring opening” reactions on GO surface facilitated the cross-linking, which elucidated a new mechanism for the generalized inorganic polymerization. With the much improved thermal- and water-stabilities, the cross-linked GO-film can help to advance high-temperature fuel-cells, electronic packaging, etc. as one of the long-sought inorganic polymers known to date.