Voltammetry at graphite electrodes: The oxidation of hexacyanoferrate (II) (ferrocyanide) does not exhibit pure outer-sphere electron transfer kinetics and is sensitive to pre-exposure of the electrode to organic solvents

► A diffusion domain model for heterogeneous electrodes is presented. ► For a diffusional species BPPG and EPPG electrodes should not exhibit appreciably different voltammetry. ► Organic solvents can alter the observed voltammetry of ferrocyanide on graphite. ► Ferrocyanide follows an inner-sphere electron transfer pathway. ► The voltammetry of ferrocyanide is shown to be influenced by the supporting electrolyte.