Electrochemical analysis of ferrocene in bicontinuous microemulsions using β- cyclodextrin modified monolayer graphene electrodes

A monolayer graphene electrode modified with beta-cyclodextrin (beta-CD) was produced via a one-step reaction using an originally synthesized pyrene derivative of beta-CD (py-beta-CD). A py-beta-CD-modified graphene electrode with a high modification density exceeding a coverage of 0.5 was obtained. Using this electrode, the electro-chemical behaviors of water-insoluble ferrocene (Fc) and of a water-soluble ferrocene derivative in a bicontin-uous microemulsion (BME) solution, consisting of a phosphate buffer (pH = 7.4), sodium dodecyl sulfate (SDS), 2-butanol, and toluene, were analyzed to investigate the effects of beta-CD modification on the redox reac-tions of these species. In the reduction reaction of water-insoluble Fc, almost no peak was observed for the unmodified graphene electrode, whereas a high peak current increase was observed for the beta-CD-modified elec-trode. The mechanism of the increase in the peak current of the reduction reaction can be derived from many small water domains formed around the beta-CD molecules on the graphene surface. These water domains form many oil-water interfaces on the surface of the graphene electrode, which act as an [Fc]+1 concentration field by interacting with SDS.

Automated summary

A monolayer graphene electrode modified with beta-cyclodextrin was prepared, and the effects of the modification on the redox reactions of water-insoluble ferrocene were investigated. The modification significantly increased the peak current of the reduction reaction by forming small water domains and oil-water interfaces on the graphene surface.