▎ 摘　　要

A simple and efficient approach to exfoliate graphene sheets in solution was reported. The principle of this strategy involved the utilization of binary solvent mixtures which exhibit moderate miscibility. At certain composition, these solvent mixtures showed much more efficient graphene exfoliation, greater than in the case of neat solvents. By adopting a combination of short-time sonication and gradual centrifugation, the resulting suspensions were found to be highly enriched in mono- and few-layer graphene sheets. The structure and morphology of nanosheets were characterized using imaging techniques and spectroscopies. Statistical analysis from imaging techniques showed that 90% of graphene aggregates were less than five layers thick with a monolayer fraction of about 10%. (c) 2012 Elsevier B.V. All rights reserved.