Kinetics of Electrocatalytic Oxidation of Gallic Acid by Activated Glassy Carbon Electrode in Acidic Medium

Abstract

An electrochemically functionalized glassy carbon (GC) electrode was prepared to study Gallic acid (GA) oxidation reaction in an acidic medium. The functionalized GC electrode was found to enhanced GA oxidation reaction in acidic medium by lowering oxidation potential and increasing corresponding current in comparison to a pristine GC. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and x-ray photoelectron spectroscopy (XPS) methods were used to analyze functionalized GC surface. The development of electropositive C=O functional groups were assumed to enhance the catalytic process. The specific capacitance of the electrode was calculated to be 92.91 μF by analysing EIS. Kinetics of GA oxidation over activated GC was calculated from CVs data. By analysing concentration dependent CVs it was found that the electrode process followed mass transfer limited first order kinetics. The GA oxidation mechanism is potential-dependent. For potentials above 0.42 V, the oxidation reaction involves the transfer of 2e− and 2H+ via a concerted mechanism, while at potentials below 0.42 V, the mechanism is stepwise. The reaction‘s standard rate constant (k°) was evaluated as 2.08×10−4 cm s−1.