文摘
The capacitance storage and cyclic voltammetry (CV) of electrochemical oxidation of phenol were investigated using IrO2–Ta2O5/Ti and β-PbO2/Ti electrodes. CV curves (0–1.2 V vs SHE) and galvanostatic charge–discharge tests indicated excellent capacitance behavior, with a specific capacitance (Cs) of 54.56 mF/cm2 and a discharge current density of 15.0 mA/cm2 for IrO2–Ta2O5/Ti, while β-PbO2/Ti exhibited a negligible Cs of 8.49 mF/cm2 and a discharge current density of 3.0 mA/cm2 in a phenol containing electrolyte. Such discrepant energy storage capacities were inversely related to the polymer formation on the anode surface and the further electrochemical oxidation of the polymer on the IrO2–Ta2O5/Ti electrode under the negative scanning potential as evidenced by Fourier transform infrared spectroscopy. Phenol oxidation and oxygen evolution properties were detected by CV scanning at potentials between 0 and 2.0 V, and electrochemical impedance spectroscopy was employed to investigate the kinetic mechanism. Experimental data showed negative potential of phenol oxidation and oxygen evolution for IrO2–Ta2O5/Ti compared to that of the β-PbO2/Ti electrode, attributed to the smaller electrode resistance and charge–transfer resistance of 1.42 and 1.71 V, respectively. Besides, organics with small molecules were detected on these two electrode surfaces under the positive scanning potential.
