Download Gamry G750 Potentiostat

Gamry G750 Potentiostat – Standard Operating Procedure
Konstantinos Gerasopoulos – September 2011
*NOTE: Dr. Michael Khbeis at the Laboratory for Physical Sciences is the owner of the equipment. Upon
his request, it should be returned immediately*
The Gamry G750 potentiostat is a computer attached unit that performs basic electrochemical
processing functions. It runs with various modules, however only the PHYSICAL ELECTROCHEMISTRY
module operates in the MSAL machine. Due to the complementarity of most processes to those run in
the Electrochemical Analyzer and the Arbin Battery test station, the basic functions that are run with this
tool include:
1. Chronopotentiometry – a constant current is applied and the voltage is plotted versus time (THIS
MODE IS USED FOR ELECTROPLATING)
2. Chronoamperometry – a constant voltage is applied and the current is plotted versus time
3. Cyclic Voltammetry (CV) – the potential is swept between two limits and the current is plotted
In this SOP, chronopotentiometry for electroplating and CV will be explained.
Section A: Electrical Connections (PLEASE READ BEFORE CONTINUING)
The electrical connections in the Gamry Instrument start from the back of the computer. Inactive cables
have been wrapped around in parafilm, and should remain like that until the device needs to be recalibrated (for re-calibration, please refer to the operating manual found on the shelf over the
profilometer). The remaining connections are grouped as follows:
i.
ii.
Green – Blue: Working and Working Sense, connected together. A black cable has been
attached to the connection point, referred to from here on as BLACK. This is the
conventional “positive” electrode.
Red – white: Counter and reference electrodes, also connected together. A red cable has
been attached to the connection point, referred to from here on as RED. This is the
conventional “counter” or “negative” electrode.
The two connecting cables have been strapped with duct tape onto the dirty bench. Please make sure
they are always firmly attached on this wall.
Section B: Chronopotentiometry for Electroplating
The process described herein is used for DC plating only with a two electrode set up.
Step 1: Connect the RED cable to your sample (i.e. the surface to be plated) and the BLACK cable to the
counter electrode (i.e. the “anode” in the electroplating set up).
Step 2: Double click on the “Gamry Framework” icon on the desktop. This opens the software interface.
Step 3: Click on the following sequence of tabs to select the “Chronopotentiometry” function:
“Experiment  Physical Electrochemistry  Chronopotentiometry”
The property menu for this function is now open
Step 4: Set the parameters in the dialog box below:
a. Type the name of your file: Unless you specify otherwise, all data files are automatically saved in the
“My Gamry Data” folder on the desktop. You can change this from the “Default” button.
b. Set your electroplating currents: This program allows you to set two different currents. If you just
want to use one current throughout the whole process, you can leave the value the same in both Step 1
Current and Step 2 Current. Note that the current value is in amperes.
c. Set your electroplating times for each of the Step Currents in the respective boxes.
d. The sample period box refers to how often the voltage vs. time data is plotted on the screen. A
moderate value of “0.6” has been given to avoid excessively long files. This can be adjusted according to
the process.
e. Upper and lower voltage limits refer to the control window of the process. If the voltage exceeds
these values, alarm messages will appear on the screen and the process could stop. Make sure you set
the values according to the expected voltage in your process.
e. The remaining parameters should be left intact.
f. When ready, click “OK”. This will start the electroplating process
Section 3: Cyclic Voltammetry
Step 1: Connect the BLACK cable to the positive electrode of your electrochemical cell (for example in a
battery, the cathode) and the RED cable to the negative electrode of the cell (in a battery, the anode)
Step 2: As in Section 2, open the main dialog window from the following path:
“ExperimentPhysical ElectrochemistryCyclic Voltammetry”
Step 3: Set the CV parameters in the dialog window below:
a.
b.
c.
d.
e.
f.
g.
h.
i.
Output file: The name of your file (as before, automatically saved in the “My Gamry Data” folder)
Initial E (v): This value should be left at “0”, vs. Eoc, as shown above.
Scan Limit 1 (V): The lower voltage limit of your scan. The option “vs Eref” should be selected.
Scan Limit 2 (V): The upper voltage limit of your scan. The option “vs Eref” should be selected.
Final E (V): The potential at which the scan will end. The option “vs Eref” should be selected.
Scan rate (mV/s): Set the desired scan rate
Cycles: The number of cycles the CV will run for
Max Current (mA): The maximum current expected in the process. This should be set adequately
high for reliable data.
All other parameters should be left identical
Step 4: When ready, click “OK”. The program will measure the open circuit voltage of the device for
approximately 10 seconds and will then prompt you to continue the experiment. Click “OK”, or “Yes”.
Using the set-up described above, the first cycle will begin from the OCV, down to the lower voltage
limit, and then back up to upper voltage limit.