Catalytic Surfaces for Electroanalysis

Abstract

In this article, electrochemical determinations based on oxidation or reduction processes that require a catalyst to obtain a current proportional to analyte concentration are described. The scope is restricted to cases where the catalyst is immobilized at the electrode surface. In general, oxidation or reduction of a substance at an electrode surface can be the basis of an analytical method as long as the electron‐transfer reaction occurs in the potential window between redox of the solvent, supporting electrolyte, and/or the electrode material. The need for a catalyst arises because only a small fraction of solutes that are predicted on the basis of standard potentials to undergo redox in an available potential window are electrolyzed in the absence of a catalyst at a sufficient rate to provide an analytically useful current. As described later, the common mode of promotion of the rate of electron transfer is by mediation. A problem that results when immobilized mediators are used is that the potential at which the current is produced is related to the mediator as well as to the analytes; hence, many practical applications of catalytic surfaces involve electrochemical detection after separation by methods such as high‐performance liquid chromatography (HPLC).

Critical Review—Electrocatalytic Sensors for Arsenic Oxo Species

“…of ruthenium, vanadium, tungsten or molybdenum), either in simple or derivatized forms. 94,95,96 Having in mind the observation that successful electrocatalytic reduction of As(V) requires adsorption or deposition, 38 followed by agglomeration, of arsenate species on surfaces of noble metal nanoparticles, application of high surface area metal oxide supports or carriers may lead to enhancement of the analytical current. To restore clean Pt surface, the arsenic deposits must be removed through application of either negative potentials, e.g.…”