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The impact of overpotential on the enthalpy of activation and pre-exponential factor of electrochemical redox reactions
Journal
Physical Chemistry Chemical Physics
ISSN
14639076
Date Issued
2022-06-22
Author(s)
Tripathi, Anand Kumar
Priyadarshani, Divya
Joy, Miji E.
Maurya, Rajan
Neergat, Manoj
Abstract
The kinetics of the V5+/V4+ redox reaction is investigated in a three-electrode configuration on a Vulcan XC-72 modified glassy carbon rotating disk electrode at four different temperatures (25 to 40 °C, with 5 °C interval). The values of enthalpy of activation (ΔH#) and pre-exponential factor (Af) estimated using the Eyring equation are in the range of 0.25-0.53 eV (24-51 kJ mol−1) and −1.3 to 5, respectively. The Eyring plots tend to diverge with overpotential, causing an increase in the values of the estimated ΔH# and Af. This is perhaps due to the retarding effect of the precipitates/adsorbates on the electrode surface. The investigation of the kinetics suggests that the V5+/V4+ redox reaction is electrocatalysed through an increase in the entropy of activation (ΔS#).