Repeating Controlled Potential Chronocoulometry

Introduction

Run a Repeating Controlled Potential Coulometry test by selecting Experiment > Physical Electrochemistry > Repeating Controlled Potential Coulometry on the Framework™ menu bar.

This is not an extension of Gamry’s Controlled Potential Coulometry; rather, it is an extension of our Chronocoulometry script. It allows the user to repeat a Chronocoulometry test over multiple cycles. The number of cycles must be a positive integer.

This is a multipurpose test. Many uses involve modification of an electrode surface. Repeated plating and partial de-plating steps can create high-quality plated surfaces. This test accumulates the net harge in the steps, so it can be used to calculate the number of moles of material that have electrochemically reacted.

Setup Parameters

The Setup window for Repeating Controlled Potential Coulometry is identical to the setup for Chronocoulometry, except for the addition of a Cycles parameter.

Each cycle generates m data points, where:

m = Step 1 Time / Sample Period + Step 2 Time / Sample Period

The total number of points in the data curve is Total Points:

Total Points = Cycles × m

Immediately after setup, the number of points required for the test is compared to the maximum points allowed in a Chronocoulometry curve. If you asked for more than the allowed number of points, an error window appears. You can resolve the problem by:

  • Increasing the Sample Period
  • Reducing the Cycles
  • Reducing the Step Times

When the test is run, all pre-step actions (Conditioning, Initial Delay, etc.) are performed once. The script then:

  1. Applies the Step 1 Voltage for the Step 1 Time,
  2. Applies the Step 2 Voltage for the Step 2 Time,
  3. Increments a completed cycles counter,
  4. Stops the test if the completed cycles counter exceeds the Cycles parameter
  5. Loops back to Step 1 if more cycles are needed

Results

The result of the test is a curve containing current-, voltage-, and charge-versus-time data points. All the steps are contained within one data curve.

The data file can be opened in our Echem Analyst™ program.