How can I calculate the double layer capacitance from Cv data taken at different scan rates?

To calculate the double-layer capacitance (C_dl) from cyclic voltammetry (CV) data taken at different scan rates, you'll need to follow these steps:

Obtain CV data at multiple scan rates: Perform cyclic voltammetry measurements on your electrochemical system at various scan rates (ν). Ensure that the CV curves are recorded within a potential range where no Faradaic processes occur so that only the capacitive current associated with the double-layer capacitance is present.

Extract the capacitive current: Find the average current value (I) from the anodic and cathodic sweeps at a specific potential within the non-Faradaic region for each scan rate. This value represents the capacitive current.

Plot capacitive current vs. scan rate: Create a plot with the capacitive current (I) on the y-axis and the scan rate (ν) on the x-axis. Suppose the double-layer capacitance is the main contributor to the capacitive current. In that case, the plot should display a linear relationship, as the capacitive current (I) is proportional to the scan rate (ν): I = C_dl * (dE/dt), where dE/dt is the scan rate.

Calculate the double-layer capacitance: Determine the slope of the linear fit in the plot from step 3. The slope will equal the double-layer capacitance (C_dl), representing the proportionality constant between the capacitive current and the scan rate.

Remember that this method assumes that the capacitive current is predominantly due to the double-layer capacitance and that other factors, such as surface roughness or adsorption/desorption processes, do not significantly contribute to the current.

Panesun Tukur

Thank you for your elaborate response Chaitanya Mahajan . I followed exactly the way you recommended. Below is also a YouTube video I used to know exactly how to calculate the slope and subsequent ECSA. what do you think about the method. the link below

https://www.youtube.com/watch?v=OWWrRcOwbNI&list=PLes0TWfJ2nkb7wOcZUl1Hl7yuclQA0MAV&index=6&t=182s

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