During my investigation of the hydrogen evolution reaction (HER), I calculate the tafel slope to determine the first step reaction as volmer reaction but for indicating the second step, can the trend of Rp across overpotentials using the equivalent circuit Rs(CPE–Rp) also help indicate whether the second step in HER is Tafel or Heyrovsky?

For example:

• If Rp decreases significantly with increasing overpotential, does this suggest a Heyrovsky-limited mechanism?
• If Rp remains relatively low and constant, could that point toward a Tafel step being rate-determining?

I would highly appreciate any insights, personal experience, or relevant research papers that discuss this type of analysis or offer a direct comparison between the two.

Thank you very much in advance for your help!