Elimiantion Voltammetry with Potential Shift
| Authors | |
|---|---|
| Year of publication | 2016 |
| Type | Article in Proceedings |
| Conference | 67th Annual Meeting of the International Society of Electrochemistry |
| MU Faculty or unit | |
| Citation | |
| Field | Physical chemistry and theoretical chemistry |
| Keywords | elimination voltammetry; mercury electrode; solid electrodes; scan rate; potential shift |
| Description | The theory of elimination voltammetry with linear scan (EVLS) was published and experimentally verified for reversible, quasi-reversible and irreversible electrode systems [1,2]. To date, this method has found application not only in electroanalysis but also in the study of electroactive inorganic and organic substances on mercury, silver, or graphite electrodes [3-5]. The discussed elimination procedure can be considered a mathematical model of the transformation of current-potential curves; the model eliminates some current components while conserving others. The elimination of chosen particular currents is provided by elimination function defining a linear combination of total currents measured at different scan rates. One total current is chosen as a reference current and the corresponding scan rate is called reference scan rate, vref. For an adsorbed electroactive substance, the function that eliminates the charging and kinetic current components and conserves the diffusion current component yields a specific, sensitive, and well-developed peak-counterpeak (p-cp) signal [6-8]. The paper presents the EVLS transformation of irreversible current-potential curves where irreversible currents can be expressed in the general form Iir = vxY{E+?ln(v/vref)}, where the function Y is independent of scan rate v. Then, the EVLS function eliminating the diffusion and charging currents will be transformed for irreversible currents as follows: f(I) = 6.8284I1/2(E-?E) – 8.2426I(E) + 2.4142I2(E+?E) where we have, for the potential shift, ?E = (RT/?nF) ln2. Because the ?n value is a priori unknown, the potential shift value shall be determined experimentally. Within this context, the shift enables us to determine the ?n value, which defines the slowest steps of the investigated electrode process. Importantly, in the general sense, the expanded voltammetry procedure provides the determination of the ?n term, which is an operation not commonly achievable with standard electrochemical techniques. Moreover, the experimental verification of theoretical results indicates a significant opportunity for the expansion of an electrode potential range (potential window). |
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