Nanosized-Zinc-Mediated Self-Gelation of Graphene Oxide under Ambient Conditions.

Self-assembly of 3D reduced graphene oxide (rGO) sponges has received increasing attention in recent years. By far, chemical reduction, hydrothermal treatment, template-directed chemical vapor deposition, and electrodeposition are the typical methods. Herein, the utilization of zinc nanoparticles as a reducing agent to fabricate 3D rGO sponges is reported. The relative negative standard electrode potential of zinc to graphene oxide (GO) allowed the spontaneous formation of the rGO-Zn hydrogel. Zinc-free 3D rGO sponges were recovered by acid leaching of the zinc species and freeze-drying. This room-temperature electroless gelation is dependent on pH. The structure and electrochemical performance of the as-synthesized rGO sponges were determined by the mass ratio of Zn to GO. Comprehensive physical and chemical characterizations were utilized to understand the 3D structure evolution of the rGO sponges. The rGO sponge, with an optimized texture, showed high capacitance and good stability in 1 m H2 SO4 electrolyte.