▎ 摘　　要

A simple wet ball-milling method for exfoliating pristine graphite to graphene nanosheets is proposed. The surfactant of cetyltrimethyl ammonium bromide is utilized to greatly improve the exfoliation efficiency of graphene nanosheets. Variation of the ball-milling time is an efficient way to control the size and thickness of graphene nanosheets, as well as the level of edge defects. With an increase of ball-milling time, superior electrochemical reactivity is imparted owing to enlarged active area and increased catalytic ability. The obtained graphene nanosheets are sensitive for electrochemical oxidation of phenols (e.g., hydroquinone, p-chlorophenol, and p-nitrophenol), and thus qualified for the simultaneous sensing of trace level of phenols. The detection limits of simultaneous monitoring of hydroquinone, p-chlorophenol, and p-nitrophenol are as low as 0.017, 0.024, and 0.42 mg L-1, respectively. The proposed strategy thus opens up a new way to tune electrochemistry of graphene materials as well as to design their new applications.