Table of Contents
Electrochemist's Guide to AfterMath
Linear Sweep Voltammetry
Synonyms: Linear potential sweep chronoamperometry
Brief Description: Linear sweep voltammetry involves scanning the potential of the working electrode linearly with time at rates typically between 10 mV/s and 1000 V/s. The current is plotted as a function to potential to yield a voltammogram.
Linear sweep voltammetry is simply cyclic voltammetry without a Vertex Potential and reverse scan. Users are referred to the description on Cyclic voltammetry for more detail regarding instrument setup and acquisition. The basic setup will be discussed here. The setup panel for linear sweep voltammetry is as shown in Figure 1. The user can choose an Initial potential, Final potential and Sweep rate. Electrode range can be Auto or chosen by the user provided the range of currents for the experiments are known.
The Advanced, Ranges, and Post Experiment Conditions tabs are identical in setup to the Cyclic voltammetry tabs. Finally, a plot of the potential applied to the electrode is shown in Figure 2. Note that the flat portions at the beginning of the scan and the end of the scan are the Induction period and Relaxation periods, respectively. Details regarding these two periods are provided in separate wikis. After completion of the experiment and relaxation period, the post experiment idle conditions are applied to the cell.
Theory and Application
The user is referred to the section on Cyclic voltammetry for a discussion on theory.
Most applications of linear sweep voltammetry relate to cyclic voltammetry. However, here are a few examples where linear sweep voltammetry was applied.
In the first example,1 Cheng and coworkers used linear sweep voltammetry to examine direct methane production using a biocathode containing methanogens in either an electrochemical system or a microbial electrolysis cell by a process called electromethanogenesis. Since the production of methane from CO2 is an irreversible process, cyclic voltammetry would provide no additional benefit over linear sweep voltammetry. Linear sweep voltammetry was used to show that a biocathode produced higher current densities than a plain carbon cathode. The authors were able to show that methane can be produced directly from an electrical current without hydrogen gas.
In another example,2 Wang and coworkers used linear sweep voltammetry to examine the release of inorganic ions and DNA from an ionorganic ion/DNA bilayer film. Performing linear sweep voltammetry simultaneously with surface plasmon resonance, the researchers were able to show that the film disassembled upon sweeping the potential to more negative values. This allowed the researchers to demonstrate the controlled release of DNA for gene-targeting therapy.
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