How to measure peak current (ipa) in cyclic voltammogram with obscure baseline?

06 April 2023 2 8K Report

Hello,

I need help identifying or measuring anodic peak current (ipa).

This is the cyclic voltammogram of vanadium ions on the negative side, anodic(V2+ -> V3+) and cathodic(V3+ -> V2+) in a solution of V4+ and H2SO4 with carbon paper as working electrode and platinum mesh as current collector. Scan rate 3mV/s.

As you can see in the figure, the cathodic peak has a clear baseline, the arrow indicate scan direction. However, anodic peak does not have a clear baseline to find ipa.

As you can see, the anodic peak is extremely small if I use the slant baseline, which I think it is not quite right.

Any recommendations?

Thank you.

Kaushik Shandilya

Dear friend Kavin Teenakul

If the baseline of the anodic peak is not clear in the cyclic voltammogram, there are a few techniques you can use to identify or measure the peak current (ipa):

Use a local baseline: Instead of using a slanted baseline, you can draw a baseline that follows the local curvature of the curve just before and after the anodic peak. This can give you a better estimate of the peak current.

Use a derivative plot: You can create a derivative plot of the cyclic voltammogram, which will amplify the changes in current over voltage. The anodic peak current will be the maximum point on the derivative plot.

Use a background subtraction technique: If you have a separate cyclic voltammogram of the blank solution (without the vanadium ions), you can subtract it from the voltammogram of the sample solution to remove any background currents. This can help you identify the anodic peak current more accurately.

Use a fitting model: You can fit a model to the cyclic voltammogram that includes the anodic peak, such as a Gaussian or Lorentzian function. This can give you a more precise measurement of the peak current and other peak parameters.

It's important to note that the choice of technique will depend on the specific characteristics of your cyclic voltammogram and the level of accuracy required for your analysis.

Kavin Teenakul

Kaushik Shandilya

Hello,

Thank you for a very throughout explanation.

I tried background subtraction method, unfortunately, the background which is hydrogen evolution, produce much higher current than when vanadium ion is present.

This cause the subtracted CV to bend upward.

I could manipulate the background so that the subtracted CV does not bend too much, but I don't know if that is a valid method.

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