Cyclic Voltammetry Experimental Sequence

Run the Cyclic Voltammetry Electrochemical Energy standard technique by selecting Experiment>Electrochemical Energy>Cyclic Voltammetry from the Framework™ menu bar.

This initiates the following sequence of events:

1. The Framework creates a Runner window, and the pwr cyclic voltammetry.exp script is run in this window.
2. The script creates the first Setup dialog box and accepts changes in the parameters.
3. The script now obtains the use of the potentiostat specified during Setup and opens the data file specified in the Output name. The Runner window's Title reflects the Output filename. If the potentiostat is in use or the file cannot be opened, the script returns to the Setup dialog box.The file header information is written to the data file. This information is written to the file prior to data acquisition. If the experiment is aborted, the output file contains only this information. This header information includes: (a) Tags identifying possible analysis; (b) The current time and data; and (c) A list of setup parameters.
4. If Initial Delay is on, then the cell is turned off, and the specimen's E_oc is measured for the time specified as the Initial Delay time or until the potential stabilizes to a value less than the Stab. setting. A plot of potential versus time is always displayed. The last measured potential is recorded as E_oc. If Initial Delay is off, this step is skipped and E_oc is assumed to be 0.0 V vs. Ref.

5. The script conditions the electrode if Conditioning was specified in the Setup. Conditioning is done by applying a fixed potential for a defined time. A plot of current versus time is displayed during Conditioning.

6. Finally an actual scan occurs. The potential of the cell is set to Initial E. The potential is then swept from the Initial E to Scan Limit 1, then to Scan limit 2 and then to Final E. If Scan Llimit 2 equals Final E then the scan stops at that value. Current readings at fixed voltage-intervals are taken during the sweep. The voltage interval between steps is defined as the Resolution in the Setup dialog box.

   If the number of Cycles > 1, the potential repeats the sweep for n cycles.

   The sweep is actually a staircase ramp. The sample is potentiostatted at the Initial E, a delay of one sample period occurs (sample period = 1/Scan Rate × Resolution), and a reading of the current is taken. The potential is then stepped by a few mV as defined by Resolution, a delay of one Sample Period occurs, and the next current reading is taken. Stepping the potential, delaying and acquiring data points continues until the potential equals the Final E.

   If you selected Autoranging in Setup, at each point the current range is automatically switched to the optimal range for the measured cell current. If you selected Positive Feedback IR Compensation, all data are continuously corrected for IR-drop. If you selected Current Interrupt IR Compensation, each potential is corrected for the measured IR-drop of the preceding point.

   A plot of I vs. E is displayed during the scan.

7. The data are written to the output file, and the script cleans up and halts. After the experimental sequence is complete, the cell is turned off. The acquired data are written to the output file. The script then waits for you to click the F2-Skip button. After you do so, the script closes everything that's open, including the Runner window.