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Tag Archives: electrochemistry
Multicomponent Analysis in Voltammetry
Voltammetry is a particularly attractive technique for the analysis of samples containing two or more analytes. Provided that the analytes behave independently, the voltammogram of a multicomponent mixture is a summation of each analyte’s individual voltammograms. As shown here, if … Continue reading
Clark Electrode for Dissolved Oxygen
In amperometry we apply a constant potential to the working electrode and measure current as a function of time. Because we do not vary the potential, amperometry does not result in a voltammogram. One important application of amperometry is in … Continue reading
Effect of Scan Rate in Cyclic Voltammetry
In a cyclic voltammetry experiment, scanning the potential in both directions provides with the opportunity to explore the electrochemical behavior of species generated at the electrode. This is a distinct advantage of cyclic voltammetry over other voltammetric techniques. The illustration … Continue reading
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Tagged CV, cyclic voltammetry, electrochemistry, scan rate, voltammetry
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Cyclic Voltammetry
In cyclic voltammetry (CV) we scan the potential in both the cathodic and anodic directions. The illustration below shows a typical potential-excitation signal (a) in which we first scan the potential to more positive values, oxidizing R to O, and … Continue reading
Anodic Stripping Voltammetry
As illustrated here, anodic stripping voltammetry (ASV) consists of two steps. The first step is a controlled potential electrolysis in which we hold the working electrode—usually a hanging mercury drop or a mercury film electrode—at a cathodic potential sufficient to … Continue reading
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Tagged anodic stripping voltammetry, ASV, electrochemistry, voltammetry
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Pulse Polarography
Normal polarography has been replaced by various forms of pulse polarography, several examples of which are shown here. Normal pulse polarography (a), for example, uses a series of potential pulses characterized by a cycle of time of τ, a pulse-time … Continue reading
Normal Polarography
The first important voltammetric technique to be developed—polarography—uses the dropping mercury electrode as the working electrode. As shown here, the current flowing through the electrochemical cell is measured while applying a linear potential ramp. Although polarography takes place in an … Continue reading
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Tagged electrochemistry, limiting current, normal polarography, polarography, voltammetry
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Shape of Voltammograms
In voltammetry we measure current as a function of the applied potential. The shape of a voltammogram is determined by several experimental factors, the most important of which are how we measure the current and whether convection is included as … Continue reading
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Tagged electrochemistry, limiting current, peak current, voltammetry, voltammograms
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Origin of Faradaic Current in Voltammetry
Let’s assume we have a solution that is 1.0 mM in Fe(CN)63– is 1.0 mM. The standard state potential for the reduction of Fe(CN)63– to Fe(CN)64– is +0.356 V. If we apply a potential of +0.550 V the concentration of Fe(CN)63– at the electrode’s surface … Continue reading
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Tagged convection, diffusion, diffusion layer, electrochemistry, Faradaic current, mass transport, voltammetry
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Electrochemical Cell for Voltammetry
A typical arrangement for a voltammetric electrochemical cell is shown here. In addition to the working electrode, the reference electrode, and the auxiliary electrode, the cell also includes a N2-purge line for removing dissolved O2, and an optional stir bar. … Continue reading