Apparatus and methods for using a rotating ring–disk electrode with potentiodynamic control of both working electrodes

Abstract

When studying electrochemical processes, one of the most widely used methods of determining the reaction pathway is an electrochemical assay of products using a rotating ring–disk electrode (RRDE). An RRDE tip consists of two electron conducting parts: a centrally located disk and a ring around it. When brought into contact with an electrolyte solution, the disk and the ring both form electrodes, the potentials of which can be independently controlled by a bi-potentiostat. When the tip is rotated, reactants from the solution arrive at the disk where they undergo an electrode reaction (oxidation or reduction) at a given rate, depending on the rotation speed. The formed products leave the disk surface and due to forced convection make their way towards the ring electrode where they can undergo another electrode reaction and can thus be detected. Normally, one applies potentiostatic control to at least one of the electrodes when carrying out an RRDE experiment; albeit the simultaneous potentiodynamic perturbation of the electrodes offers an increased applicability range. This paper presents the construction of a measuring system capable for the “bi-potentiodynamic” perturbation of two working electrodes, and demonstrates the use of such methods in case of a few chosen example systems.

Analysis of quasi-reversible cyclic voltammograms: Transformation to scan-rate independent form

“…For testing the properties of the transformation of Eq.8, simulated CVs were generated by a computer program. This was based on the explicit Euler method for solving the partial differential equation relevant to the transport of the redox species [7], taking also into account the quasireversible charge transfer [8] and solution resistance [9].…”

Rotating Disk and Ring–Disk Electrodes

“…Although most of the standard RRDE techniques involve static control (at least at one of the electrodes), and thus these techniques focus on the study of either collection or of shielding effects, recent advances in the instrumentation of RRDE systems also enable the simultaneous study of both effects. 44 This necessitates the application of potentiodynamic control of both the disk and the ring electrode at the same time. For example, by a slow scanning of the disk potential and a synchronous high-rate cycling of the ring, shielding and collection effects accompanying oxygen reduction on gold were analyzed 45 (see Fig.…”

(Invited) Interpretation of Certain Features of the Interface Stress vs. Electrode Potential Curves of Gold with the Help of Dual Dynamic Voltammetry

“…The RRDE measurements were carried out at 25.0 °C by using our self-built electrochemical workstation (19) incorporating a bi-potentiostatic assembly of XPot devices manufactured and modified specially for our needs by Zahner Elektrik, Kronach, Germany. The oxide on the gold surface was formed by potential cycling up to the so called "Burshtein minimum" at which electrode is assumed to be covered with one monolayer of adsorbed oxygen and the formation of three-dimensional structures ("higher Au-oxides") is negligible.…”