Kinetic parameters for glycerol electrooxidation over nitrogen- and fluorine-doped composite carbon:Dynamic electrochemical impedance spectroscopy analysis based

Abstract

This study explores the mechanistic, kinetic process and parameters of nitrogen and fluorine-doped activated carbon black composite catalyst during glycerol electrooxidation in alkaline so under some precise experimental parameters. The influence of catalyst and electrochemical impedance spectroscopy (EIS) perturbation amplitude were systematically studied. The kinetic parameters from steady-state measurement and microkinetic modelling study reveal that glycerol electrooxidation undergoes complicated mechanism. From the chronoamperometry study, the nitrogen-doped sample (ACB-N2) shows a remarkable activity and stability, but the performance was improved upon the simultaneous doping of fluorine to form ACB-N2F2. The best rate constant was obtained by ACB-N2F2 (7.335 × 10−3), which is by far greater than those of ACB-N2 (2.533 × 10−3) and ACB-F2 (2.012 × 10−3) for steady-state. The slope obtained from the Tafel plot of both the voltammetry and the non-linear electrochemical impedance spectroscopy measurement also confirms the superior performance of ACB-N2F2 compared to ACB-N2 and ACB-F2. The rate constant of ACB-N2F2 is almost 6 times of that of ACB-N2, and 4 times of the of ACB-F2 for the forward sweep. The exchange current density of ACB-N2F2 is almost 7 times of that of ACB-N2, and 3 times of the of ACB-F2 for the forward sweep. The methods in this study for evaluation of glycerol electrooxidation kinetic process and kinetic parameters could be used to investigate other electrocatalysts