Study of the oxidation of phenol at the poly-tropism platinum electrode

The process of electrochemical oxidation of phenol on the poly-tropism platinum electrode has been investigated by electrochemical methods such as cyclic voltammetry, Tafel curves and electrochemical impedance spectra technique. The cyclic vollammograms were measured with several potential sweep rates of 10, 20, 50, 100 and 200 mV/s, using 0.25 mol/L Na₂SO₄ as sustained electrolyte. The regular of cyclic voltam-mograms of 500 mg/L phenol oxidation on the Pt electrode was further studied. It was indicated that electrochemical oxidation of phenol on platinum electrode was irreversible process and the oxidation peak appeared at 0.926 V (vs. Ag/AgCl) with the scanning rate of 50 mV/s. Furthermore, the dependence of the phenol oxidation peak current on the CV scanning rate was also studied and it could be concluded that the phenol oxidation process was controlled by electrochemical oxidation process of the diffusion and adsorption step. The Tafel curves were measured in 0.1 and 1.0 mol/L H₂SO₄ solution, respectively. The Tafel curves were used to analyze the Pt electrode oxygen evolution reaction and the slope of the Tafel curve is 149 mV. Electrochemical impedance spectra technique was used to studied phenol electrochemical oxidation reaction, and a semicircle of capacitor resistance was shown in EIS due to the phenol adsorption in high frequency.