Evaluation of the Electrocatalytic Activity of Antimony-Doped Tin Dioxide Anodes toward the Oxidation of Phenol in Aqueous Solutions

Antimony-doped tin dioxide electrodes supported on titanium have been used in the electrochemical treatment of aqueous solution containing phenol. Ti/SnO2-Sb anode has high efficiency in the elimination of phenol, but its use is hindered by its short service life. The introduction of platinum in the oxide layer (3 or 13 atom %) increases the electrode service life up to two orders of magnitude. The electrocatalytic activity of the electrodes toward phenol oxidation has been analyzed with respect to the amount of platinum in the electrode composition. Voltammetric studies show that the oxidation potential of phenol decreases with the amount of platinum in the oxide layer. The activity for phenol oxidation per electroactive site is higher with the Sb-doped SnO2 electrode within the zone of electrochemical stability of the solvent. Galvanostatic electrolysis of phenol solutions was performed analyzing several factors that affect the efficiency of the elimination process, such as anode composition, cell design, current density, and phenol concentration. The electrode containing platinum (3 atom %) presents the highest efficiency for phenol removal, even higher than Sb-doped SnO2.