Solution-Processed Graphite Membrane from Reassembled Graphene Oxide

Abstract

A new synthesis route of a solution-processed highly conductive self-standing graphite membrane from reassembled graphene oxide (GO) has become one of the intensive research focus, because of its immense application opportunities. Previously demonstrated techniques were limited by the unstable reduced graphene oxide (RGO) dispersion and agglomeration during chemical reduction without any surfactant. This results in poor packing morphology and low electrical conductivity of the RGO membrane. Here, we report a novel synthesis route of a highly concentrated RGO solution from exfoliated GO, which results highly conductive and self-standing RGO membrane without using any binders or organic solvents. Our low-temperature reduction method is significantly different from previous investigations in which controlling the reduction rate by lowering the reduction temperature of the GO solution and collision probability was the key factor in preventing random agglomeration. Further high-temperature reduction of the RGO membrane gave rise to a reassembled graphite structure containing negligible oxygen content (O 1s/C 1s = 0.005), and high electrical conductivity (up to 1.6 × 105 S/m) without disintegration of its self-standing feature. This result is better than any previously reported value. Developed RGO membrane could be mass-produced for various flexible device applications. The in-plane alignment and through-thickness consolidation of GO and RGO membranes using vacuum-filtration and thermal treatment successfully ensured the synthesis of highly conductive, mechanically robust RGO and graphite membranes.