Ultrasound exfoliation of graphite in biphasic liquid systems containing ionic liquids: A study on the conditions for obtaining large few-layers graphene.

Affiliation

MackGraphe (Graphene and Nanomaterials Research Center), Mackenzie Presbyterian University, Rua da Consolação, 930, São Paulo, SP, Brazil. Electronic address: [Email]

Abstract

Herein we describe a successful protocol for graphite exfoliation using a biphasic liquid system (water/dichloromethane, DCM) containing ionic liquids (ILs; 1,3-dibenzylimidazolium benzoate- and 1-naphthoate). The use of (surface active) IL and sonication led to stable DCM/water (O/W) emulsion, which enhanced graphene formation, suppressed its re-aggregation and decreased shear/cavitation damage. The O/W emulsion stabilization by the ILs was studied by dynamic light scattering (DLS), whereas their interaction with the graphene sheets were described by Density Functional Theory (DFT) calculations. Moreover, a comprehensive investigation on cavitation-based exfoliation in the O/W systems was performed to assess the importance of operational parameters, including, the type of ultrasound processor, ultrasound power and insonation, and the influence of the exfoliation medium.

Keywords

Biphasic liquid system,Cavitation-based emulsification,Graphene,Ionic liquids,Liquid phase exfoliation,