No it will not affect LSV data. If you want to see more of the semicircle you need to expand your frequency range (but maybe you are already at the limit of your instrument's range?)

As Nigel Patterson suggested, you should try to extend the frequency range, so that measurements at lower frequencies may complete the semicircle in the Nyquist Plots, or reveal an extension of it, usually as a tail.

You're correct in identifying that a complete semicircle in a Nyquist plot is often desirable for extracting accurate parameters. It typically represents the charge transfer resistance (Rct), which is crucial for understanding the kinetics of electrochemical reactions. However, the absence of a complete semicircle doesn't necessarily invalidate your HER data.

Impact on HER Data

• Sample Resistance (Rs): As you mentioned, Rs can usually be determined even from an incomplete semicircle. This is essential for correcting the iR-drop in your LSV data.
• Charge Transfer Resistance (Rct): Without a complete semicircle, accurately determining Rct is challenging. This parameter is vital for kinetic analysis and comparing different catalysts.
• Other Parameters: Other parameters like double-layer capacitance can also be affected by an incomplete semicircle.

Enhancing the Nyquist Plot

If a complete semicircle is crucial for your analysis, consider these strategies:

Thank you for all of you!