Mechanism and Kinetic Parameters of Functionalized Composite Carbon-Based Electrocatalyst During Oxidation of Glycerol Using Dynamic Electrochemical Impedance Spectroscopy

This research investigates the glycerol oxidation reaction on carbon-functionalized composites using Tafel behavior, exchange current density (ECD), rate constant, and dynamic electrochemical impedance spectroscopy (DEIS) data fitting. The aim is to gather essential data for fabricating glycerol electrooxidation electrodes in an alkaline medium. Corrected net current analysis reveals that the nitrogen-doped activated carbon black composite electrode (ACB-N2) exhibits the highest instantaneous catalytic activity, with a net current density of 1.3 mA cm−2 at 1.0 V vs. SCE. However, the dual-doped nitrogen and fluorine composite (ACB-N2F2) demonstrates the lowest Tafel slope (177.97 mV dec−1), indicating faster kinetics, and it maintains superior electrochemical stability during chronoamperometric testing. ACB-N2F2 exhibits the highest ECD (1.0129 mA cm−2) and the lowest Ts and rate constant (2.62 × 109 cm s−1), indicating the fastest electron transfer. These findings suggest that while ACB-N2 offers the highest net GOR activity, ACB-N2F2 combines kinetic efficiency and long-term durability, making it a promising candidate for practical GOR applications. The rate-determining step is water adsorption at low overpotentials (0.55 V, 0.5 V, and 0.4 V vs. SCE for ACB-F2, ACB-N2, and ACB-N2F2, respectively).