Self-Assembly of Reduced Graphene Oxide into Three-Dimensional Architecture by Divalent Ion Linkage

Gel-like three-dimensional (3D) reduced graphene oxide (rGO) structure can be achieved upon connecting rGO sheets with divalent ions (Ca2+, Ni2+, or Co2+) and water molecules via hydrothermal treatment. In this architecture, the rGO sheets, water molecules, and divalent ions play the role of skeleton, filler, and linker, respectively. The rGO sheets in the gel-like 3D rGO structure mainly exist as single or double layers by the isolation of the interlamellar water molecules. Since a large amount of water (∼99 wt %) facilitates the introduction of polyvinyl alcohol as a strengthening agent, hereby dried 3D rGO structure with micropores could be obtained after freeze drying.