Simple, green and high-yield production of single- or few-layer graphene by hydrothermal exfoliation of graphite

Abstract

Graphene is widely used as promising electronic material and devices, owing to its exceptional electronic and optoelectronic properties. Up to now, defect-free graphene has been limited to the method for controllable, reproducible and scalable mass production. A simple, green, and nontoxic approach for large-scale preparation of high quality graphene is produced by exfoliation of graphite sheets collaborated with intercalant (FeCl₂) under hydrothermal conditions, the absence of defects or oxides in graphene with a yield up to 10 wt% can be a practical application and industrial process such as optical limiters, transparent conductors, and sensors. This new process could potentially be improved to give a yield of up to 35 wt% of the starting graphite mass with sediment recycling. We show with experiments and theories that exfoliation graphene is the result of a combined action by diminishing the van der Waals interactions between graphite layers and the shear force drove by the Brownian motion of H₂O and FeCl₂ molecules. Hydrothermal exfoliation has potential applications in the exfoliation of other layered materials (e.g. BN, MoS₂) and carbon nantubes, and in the synthesis of intercalation compounds, nanoribbons, and nanoparticles, thus opening new ways of exfoliation engineering.