Au Disk Electrode Research Articles

This research contribution is in commemoration of the life and science of I. M. Kolthoff (1894-1993). Pulsed electrochemical detection at the ring of a ring-disk electrode applied to a study of amine adsorption at gold electrodes

Results are shown for application of a Au-Au rotated ring-disk electrode to an investigation of the adsorption and desorption of model organic the compounds in alkaline media. Aliphatic amines are not detected at constant potential, and therefore, a multistep potential five form is applied at the ring electrode to achieve their pulsed electrochemical detection. On the basis of the ring-disk results, the potential-dependent nature of amine adsorption and desorption at the Au disk electrode is easily evaluated. Furthermore, the significance of this information is demonstrated for the optimization of a PED wave form applied for the detection of aliphatic amines separated by high-performance liquid chromatography. Proper choice of the potential for oxide reduction in the PED wave form allows for simultaneous preadsorption of amine compounds with the benefit of enhanced detection sensitivity

Electrocatalysis of Anodic Oxygen‐Transfer Reactions: Oxidation of Phenol and Benzene at Bismuth‐Doped Lead Dioxide Electrodes in Acidic Solutions

The electrocatalytic activities are compared for pure β‐lead dioxide electrodes and bismuth‐doped lead dioxide electrodes for oxidation of dimethylsulfoxide (DMSO), phenol, and benzene in acidic media. A correlation is observed between the bismuth content of films on Au disk electrodes and the apparent heterogeneous rate constant for conversion of DMSO to . The oxidation of phenol occurs at a transport‐limited rate for both the and film electrodes; however, the electrodes exhibit significantly greater stability against surface fouling by polymeric films. This is a direct benefit of the greater electrocatalytic activity of electrodes for oxidation of phenol beyond the phenolic radical. A ring‐disk experiment for benzene oxidation at a disk demonstrates that o‐benzoquinone and p‐benzoquinone are produced at the disk in the ratio ca. 0.25. However, the total ring current for reduction of these products from the disk reaction is significantly below that predicted from the disk current, and it must be concluded that a significant amount of electroinactive species is produced at the disk. This production is speculated to occur with and probably corresponds to a ring‐opening reaction with production of one or more organic acids. The product solution from exhaustive electrolysis of benzene contains p‐benzoquinone as the only electroactive product; hence, the o‐benzoquinone is concluded to undergo further oxidation at the electrode to one or more electroinactive products.

A combined voltammetry and electrochemical quartz crystal microgravimetry study of the reduction of aqueous Se(IV) at gold

The reduction of Se(IV) in 0.5 M Na 2SO 4 is complex and does not proceed via the Se(IV) → Se(0) → Se(II-) scheme considered by most previous authors. A combined use of voltammetry and electrochemical quartz crystal microgravimetry techniques shows that the direct 6e − Se(IV) → Se(II-) reduction pathway competes with the initial four-electron process. Coupling with a subsequent (fast) chemical reaction between Se(II-) and Se(IV) results in the further deposition of Se(0) at the electrode surface. The electrochemical behavior at more negative potentials reflects a complex interplay of the four-electron and six-electron reduction processes and the chemical reaction along with the effect of Se(II-) ions stripped from the initial selenium layer. Thus the delicate balance between these is influenced by two variables, namely the potential and the Se(II-) concentration in the electrolyte. Further data in support of our mechanistic scheme are furnished by measurements with a Au disk electrode oriented “face-down” in the cell as well as by hydrodynamic voltammetry experiments.

Kinetics of nitrate reduction by cobalt-cyclam incorporated Nafion® redox polymer

Cobalt-cyclam (cobaltic complex of 1,4,8,11-tetraazacyclotetradecane) incorporated Nafion® film Au disk electrodes were employed to catalyze the reduction of nitrate in concentrated sodium hydroxide solution. These redox polymer electrodes displayed excellent catalytic activity. The kinetic characteristics of this catalytic system have been determined by the techniques of rotating-disk electrode voltammetry and cyclic voltammetry with the aid of the developed kinetic models. The rate constant of the electrocatalytic reaction, the diffusion coefficient of nitrate in the films and some other parameters were also determined by electrochemical methods.