I need to know how I can calulate electrochemical surface
area (ECSA) for comparing OER-ORR catalytic activity,
ECSA is easy for pure Pt catalysts, but very difficult to accurately quantify for any non-Pt surfaces. As mentioned above, the Hupd method is the most accurate method for Pt and a value of 210 uC/cm2 can be used to convert from the anodic H-stripping charge to Pt ECSA. The value of 420 uC/cm2 for CO stripping also works, but this value is derived based on the geometry of a Pt surface and is not accurate for other materials.
If your catalyst is non-Pt (I assume it is because Pt is a poor catalyst for OER) I agree with Dr. Abad's comments above. I've included a link of a paper by Jaramillo et al. which details the ECSA normalization techniques for non-Pt OER catalysts.
http://pubs.acs.org/doi/abs/10.1021/ja510442p
Do you know the diffusion coefficient in your solution? If you know it you can apply the randles-sevick equation to determine the ECSA. Therefore, you will need to do CV at different scan rates.
I think that, in your case, the diffusion coefficient is not required, as you can evaluate the A·D^0.5 product. If you keep the experimental conditions (solution composition, temperature, stirring, etc.), your D will remain constant.
Hi Ellie,
Iintegrating the hydrogen peak in CV data with the method hydrogen under potential deposition (HUPD) is a common method. You will easily find more info in the internet.
An even more advanced method is discussed in Engl et al: Second Cycle is Dead: Advanced Electrode Diagnostics for High-Temperature PEM Fuel Cells, Journal of the Electrochemical Society 161 (4), F599-F505 (2014).
Kind regards
Peter
My previous answer has disappeared.
As summary, I suggest you to apply different scan rates and applying the randles-sevick equation you will be able to calculate the A·D^0.5 product. Then, if you keep your experimental conditions, D will remain constant and you will be able to compare your catalytic activity.
I think that you must do CO stripping experimentS and then you have to integrate CO peak. You will take the charge of the peak (in Coulomb) and you can calculate the ECSA from the ECSA=Q/420 (mCb/cm^2).
ECSA is easy for pure Pt catalysts, but very difficult to accurately quantify for any non-Pt surfaces. As mentioned above, the Hupd method is the most accurate method for Pt and a value of 210 uC/cm2 can be used to convert from the anodic H-stripping charge to Pt ECSA. The value of 420 uC/cm2 for CO stripping also works, but this value is derived based on the geometry of a Pt surface and is not accurate for other materials.
If your catalyst is non-Pt (I assume it is because Pt is a poor catalyst for OER) I agree with Dr. Abad's comments above. I've included a link of a paper by Jaramillo et al. which details the ECSA normalization techniques for non-Pt OER catalysts.
http://pubs.acs.org/doi/abs/10.1021/ja510442p
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