I want to interpret the data for the cathode catalyst analysis from the cyclic voltammetry curve therefore I want to know how to read the reduction potential for the oxygen reduction reaction. And also for ERHE (reversible hydrogen electrode) how to use the Nernst equation.
you need to identify the cathodic (reduction) peak corresponding to the ORR process. Here are the steps:
1. Locate the cathodic peak in the CV curve: The cathodic peak for the ORR will appear as a negative current (reduction) peak in the cathodic (negative) potential region of the CV curve.
2. Determine the peak potential: The potential at which the cathodic peak current occurs is the peak potential (Ep,c) for the ORR. This potential represents the reduction potential for the ORR under the specific experimental conditions.
To convert the reduction potential obtained from the CV to the potential versus the reversible hydrogen electrode (RHE) scale, you can use the following equation:
E(RHE) = E(measured) + E(ref) + 0.059 × pH
Where: E(RHE) is the potential vs. RHE E(measured) is the potential obtained from the CV experiment (vs. the reference electrode used) E(ref) is the potential of the reference electrode used in the experiment (e.g., Ag/AgCl, Hg/HgO, etc.) against the standard hydrogen electrode (SHE) 0.059 is the Nernst slope (V/pH) at 25°C pH is the pH of the electrolyte solution
For example, if you used an Ag/AgCl reference electrode (E(ref) = 0.197 V vs. SHE at 25°C) in a 0.1 M KOH solution (pH = 13), and the ORR reduction peak potential (Ep,c) from the CV was -0.3 V vs. Ag/AgCl, then:
E(RHE) = -0.3 V + 0.197 V + (0.059 × 13) = 0.964 V vs. RHE
This calculation converts the potential obtained from the CV to the RHE scale, which is a widely used reference for reporting potentials in electrochemical systems, particularly for fuel cell and metal-air battery research.
It's important to note that the potential values obtained from CV experiments can be influenced by various factors, such as scan rate, electrolyte composition, and electrode surface conditions. Therefore, it is essential to carefully consider and report the experimental conditions when interpreting and comparing CV data.