The impact of overpotential on the enthalpy of activation and pre-exponential factor of electrochemical redox reactions

Anand Kumar Tripathi; Divya Priyadarshani; Miji E Joy; Rajan Maurya; Manoj Neergat

doi:10.1039/d2cp00404f

The impact of overpotential on the enthalpy of activation and pre-exponential factor of electrochemical redox reactions

Phys Chem Chem Phys. 2022 Jul 6;24(26):16031-16040. doi: 10.1039/d2cp00404f.

Authors

Anand Kumar Tripathi¹, Divya Priyadarshani², Miji E Joy¹, Rajan Maurya¹, Manoj Neergat¹

Affiliations

¹ Department of Energy Science and Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India. nmanoj@iitb.ac.in.
² Centre for Research in Nanotechnology & Science, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.

PMID: 35730802
DOI: 10.1039/d2cp00404f

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 (A_f) 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 A_f. 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^#).