Discrimination of Inner- and Outer-Sphere Electrode Reactions by Cyclic Voltammetry Experiments

Abstract

A laboratory experiment for undergraduate students who are studying homogeneous and heterogeneous electron-transfer reactions is described. Heterogeneous or electrode reaction kinetics can be examined by using the electrochemical reduction of three FeIII/FeII redox couples at platinum and glassy carbon disk electrodes. Cyclic voltammetric measurement is suitable for determining the electrode-reaction rate constants. The dependence of the rate constant on the electrode materials enables the students to discriminate and discuss the mechanism of the electrode reaction. The experiment is completed in a 5-h laboratory period for pairs of students in analytical chemistry lab class. This material is also suitable for an inorganic chemistry lab class.

Links between electrochemical thermodynamics and kinetics

“…the redox couples 1 and 2, are equal to each other: the E cell value progressively lowers, till reaching 0 at the equilibrium expressed by Eq. (18).…”

Time-resolved X-ray absorption spectroelectrochemistry of redox active species in solution

“…3.1. Electrochemistry Indeed, this type of electron transfer is associated with the adsorption of the chloride ligands of the FeCl 3 complex on the glassy carbon electrode, which induces a reorganization of the ligands around the Fe ion upon reduction of Fe(III) and reoxidation of Fe(II), hence the irreversibility of the wave (Tanimoto & Ichimura, 2013). A comparison between two CVs measured in the XAS-spectroelectrochemical cell and in a conventional electrochemical cell is shown in Fig.…”

Electroanalytical Investigation of 2,2′,7,7′‐Tetrakis(diphenylamino)‐9,9′‐spirobifluorene

“…Therefore, the measured value of Δ E p at various scan rates allows a determination of the value of Ψ. As shown in Figure , the Ψ values were extracted from the CVs at various potential scans, and Ψ shows a linear relationship with 1/ν 1/2 ( y = 3.26 × 10 − 1 × x − 0.418, R 2 = 0.990). The value of k o ′ of spiro‐TAD was finally calculated to be 3.21 × 10 −2 cm/s using Eq.…”

“…Linear relationship between dimensionless kinetic parameter, Ψ and ν 1/2 obtained from theoretical relationship between dimensionless kinetic parameter, Ψ and peak‐to‐peak potential separation (Δ E pp ) …”