Clay-modified Electrodes: a Review

-Clay-modified electrode research indicates that adsorbed complexes are electroactive if the adsorption sites are clay edges. Interlayer adsorbed complexes may be electroactive ifa charge shuttle is added or if interlayer swelling is large. Conductivity of the film towards anionic species depends upon the swelling of the clay, which depends on the electrolyte concentration and speciation. The diffusion coefficients measured by electrochemical experiments agree well with alternative measurements. Key Words--Adsorption, Clay-modified electrode, Conductivity, Diffusion, Electrochemistry. I N T R O D U C T I O N Modified electrodes have been extensively used in the last decade by electrochemists attempting to control the direction and extent of electrode reactions. A variety of electrochemical techniques have been developed for the purpose of elucidating the formal potential of the electroactive substance and the diffusion coefficients of the reactants and products within the film. Clay-modified electrodes have attracted the attention of many electrochemists because of the ion exchange properties of the clay and because of the unique layered structure of the material. No review of the clay-modified electrode field has been published in the clay literature. A summary of the types of experiments performed to date and the information obtained from those experiments may stimulate further input from the clay community into the field of modified electrode electrochemistry. DESCRIPTION OF MODIFIED