Chronoamperometric study of proton transfer/electron transfer in solid state electrochemistry of organic dyes

Abstract

Chronoamperometric data for proton-assisted reduction/oxidation of a series of dyes, namely, alizarin, purpurin, luteolin, morin, and indigo are compared with the predictions of the model of Lovric and Scholz for redox conductive microcrystals assuming electron and proton hopping in mutually perpendicular directions. Upon the attachment of solid dye microparticles to paraffin-impregnated graphite electrodes in contact with aqueous electrolytes in the pH range between 4 and 7, an excellent agreement between theory and experimental data was obtained. The diffusion coefficients of electrons and protons across dye microcrystals were estimated as 5×10−7 cm2 s−1 and 1×10−10 cm2 s−1, respectively.