Simple Electrochemical Procedure for Measuring the Rates of Electron Transfer across Liquid/Liquid Interfaces Formed by Coating Graphite Electrodes with Thin Layers of Nitrobenzene

A simple, new method is described that allows the rates of electron transfer across liquid/liquid interfaces to be measured with unprecedented ease. The method takes advantage of thin layers of organic liquids that adhere to the surface of pyrolytic graphite electrodes. The method was applied to the nitrobenzene/water interface. Redox reactants dissolved in the nitrobenzene included decamethylferrocene and zinc tetraphenylporphyrin. Reactants in the adjoining aqueous phase were multiply charged anions, including Fe(CN) 6 3-/4-, Ru(CN) 6 4-, Mo(CN) 8 4-, and IrCl 6 2- . Rate constants for cross-phase electron transfer were evaluated and compared with those obtained in recent studies that employed the scanning electrochemical microscope that was invented and developed by A. J. Bard and co-workers.