In CO2 reduction or water oxidation, how to determine over-potential? Is it from LSV or CA graph?
Dear Shalini,
You can perform Linear Sweep Voltammetry analysis at scan rate ranging from 5- 50 mV/sec. From the LSV plots, you can prepare a Tafel plot by plotting log of absolute current density (x-axis) and voltage (y-axis).
For further information, you can go through this paper:- Article Oxidized Laser‐Induced Graphene for Efficient Oxygen Electrocatalysis
Thanks
Dear Shalini,
Overpotentials can be determined by knowing the reversible potentials of investigated reaction (Nernst equation). So the overpotentials at different current densities can be determined as a difference between actual potential, and thermodynamic reversible potential. For example, in the oxygen evolution reaction at pH = 11, at the current density of 10 mA cm-2, the actually measured potential is 0.8 V vs SHE. Thermodynamics potential is
Er(O2|OH-) = 1.23 - 0.0591pH = 0.58 V vs SHE. Hence the overpotential is
n = 0.8 - 0.58 =0.22 V
As Branimir N. Grgur mentioned, over potential is equal to difference between experimental potential and thermodynamic reversible potential.
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