Voltage dependent reduction rates of graphene oxide in cell culture medium, deionized water, and an ionic liquid

Abstract

The reduction rate of graphene oxide (GO) in cell culture media (Roswell Park Memorial Institute (RPMI) medium), deionized water and an ionic liquid (1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, EMIM:TFSI) has been clarified, including the voltage and time dependence, by a non-electrical measurement method. The method utilizes the color change associated with the reduction of a GO film, from near transparent to black. The reduction of GO was found to be electrolyte dependent and no reduction occurred without an electrolyte facilitating the reduction, as expected. An increase in the reduction rate was observed for both aqueous media compared to EMIM:TFSI, a non-aqueous reduction medium. The reduction in RPMI medium was slightly faster than in deionized water following a voltage dependent reduction rate of V8, attributed to the complex mixture of biomolecules and ions constituting the cell culture medium, compared to the voltage dependence of V3 for the reduction in EMIM:TFSI. Our results indicate a strong influence on the reduction rate stemming from water splitting.