Graphene production via supercritical fluids

Abstract

Since supercritical fluids possess low interfacial tension, excellent wetting of surfaces and high diffusion coefficients, they have been employed to intercalate and delaminate tightly-stacked layered materials such as silicates. In recent years, many researchers have begun to explore the possibility of using SCFs as intercalators to penetrate into the nano-gaps of graphite, and exfoliate it into graphene sheets. Although this SCFs intercalation and exfoliation approach is experimentally confirmed to be efficient and promising to produce graphene in large-scale with low-cost, it does not receive the attention it deserves. To arouse interest and reflection on this approach, this review is organized to summarize the recent progress in graphene production by SCFs technology. In this review, the process of SCFs intercalation and exfoliation method is decomposed into three stages, the mechanisms and influence factors for each stage are analyzed, the recommendations for graphene quality improvement are provided, the advantages and challenges of SCFs technology on graphene large-scale production are also summarized. Besides the ability of efficient intercalation, supercritical water or alcohol also can be used as reducing agents to produce reduced graphene oxide from graphene oxide, this SCFs reduction approach is also included in this review.