Surfactants used for dispersion of graphenes exhibit strong influence on electrochemical impedance spectroscopic response

We show here that electrochemical impedance spectroscopy response of graphene is dramatically influenced by presence/absence of surfactants. In many protocols for the production of graphene surfactants are employed in order to favour the exfoliation process and to prevent the sheets from re-aggregation. It was already demonstrated in previous works that surfactants have unfavourable effect on the electrochemistry of graphene. Here for the first time we studied the effect of the surfactant using electrochemical impedance spectroscopy as detection technique. The impedimetric response of a multi layered graphene structure was studied in the presence and in the absence of bile salt sodium cholate. The study was also extended to other graphenes (various mixtures of single and few layer graphenes) in order to see the influence of the surfactant on the different number of layers. We believe that our findings have important implications for future works using impedimetric detection on graphene surfaces. (C) 2011 Elsevier B.V. All rights reserved.