From crumple conformation to gel configuration of reduced graphene oxide: The cation induction engineering

Abstract

Spatial conformation of condensed state graphene is fundamentally important for its material properties, while its rational design or control is of great challenge. Herein, reduced graphene oxides with diverse crumple conformations are synthesized facilely and effectively by using electrostatic force from cation-oxidized functional group and cation-π interactions through NaCl/MgCl2/AlCl3 assisted hydrothermal reduction. A phase map for crumple conformation and gel configuration transitions of the reduced graphene oxides is established, where intramolecular effect of mono-valent cation and intermolecular effect of di-/tri-valent cations are captured and utilized to tune the crumple degree or gelation process. Desired material features, including specific surface area and surface functional groups, can be finely modulated via crumple conformation or cation interaction, and enable the reduced graphene oxides to present an outstanding rate capability of 68.8% and unparalleled areal capacitance of 98.0 μF/cm2 at 100 A/g in symmetric aqueous supercapacitors. This study broadens the topological behavior spectrum and stimulates the conformation engineering methodology of reduced graphene oxides, facilitating the development of novel graphene-based materials.