Tunable solution-processable anodic exfoliated graphene

Abstract

Electrochemical exfoliation of graphite is an emerging approach to provide large scale, low cost, efficient and reliable production of high quality, low defect and solution-processable graphene. The use of a sulphuric acid electrolyte allows rapid and efficient anodic graphite exfoliation. However, the highly oxidative process in this electrolyte promotes hydroxyl radicals. These degrade the carbon lattice structurally, hence compromising the quality of graphene produced. Here, we report a simple and effective way to overcome this challenge; the use of an additive to scavenge hydroxyl radicals. The addition of a small volume percentage of ethylene glycol acts to scavenge hydroxyl radicals. Furthermore, it is readily adsorbed onto the intercalated graphite surface, and therefore also serves as an oxidative prevention layer. As a result, the damage on the graphitic structure is greatly minimized, resulting in a low defect and high quality few layers graphene, with high yield (>80%) and a low degree of oxidation with a C/O ratio of 16.9. The graphene solution-processability is readily tuned and improved with stable dispersions up to 5mg/mL in dimethylformamide. This new strategy of a simple and low cost dual purpose additive in scavenging hydroxyl radicals and providing an oxidative prevention layer to efficiently tune the graphene quality and solution-processability; holds promise in industrial scale mass production of high quality graphene.