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

Anna P Godoy; Petra Ecorchard; Hynek Beneš; Jakub Tolasz; Darina Smržová; Leandro Seixas; Jairo J Pedrotti; Eunezio A T de Souza; Omar A El Seoud; Ricardo K Donato

doi:10.1016/j.ultsonch.2019.01.016

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

Ultrason Sonochem. 2019 Jul:55:279-288. doi: 10.1016/j.ultsonch.2019.01.016. Epub 2019 Jan 16.

Affiliations

¹ MackGraphe (Graphene and Nanomaterials Research Center), Mackenzie Presbyterian University, Rua da Consolação, 930, São Paulo, SP, Brazil.
² Institute of Inorganic Chemistry of the CAS, v.v.i., 25068 Řež, Czech Republic.
³ Institute of Macromolecular Chemistry of the CAS, v.v.i., Heyrovsky Sq. 2, 16206 Prague 6, Czech Republic.
⁴ Institute of Chemistry, University of São Paulo, Av. Professor Lineu Prestes, 748, 05508-000 São Paulo, SP, Brazil.
⁵ MackGraphe (Graphene and Nanomaterials Research Center), Mackenzie Presbyterian University, Rua da Consolação, 930, São Paulo, SP, Brazil. Electronic address: ricardo.donato@mackenzie.br.

PMID: 30712861
DOI: 10.1016/j.ultsonch.2019.01.016

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.