Performance of Gd-doped Ti-based Sb-SnO₂ anodes for electrochemical destruction of phenol

The performance of electrodes for the electro-catalytic decomposition of a model pollutant (phenol) was enhanced using Gd-doped Ti/SnO₂-Sb electrodes prepared by a thermal deposition method. Phenol degradation followed first-order rate kinetics, with the maximum rate achieved using a 2% Gd doping level (molar ratio based on Gd:Sn) for tests conducted over a doping range of 1-10%. The first-order rate constant with 2% Gd was 0.044 min^-1, versus 0.026 min^-1 obtained with the control (plain Ti/SnO₂-Sb). TOC removal and UV scans revealed that different intermediates were produced for different Gd contents, and that destruction efficiencies of these intermediates also varied with Gd doping levels of 1-5%. Electrodes were characterized by scanning electron microscopy, X-ray diffraction, electron dispersive spectrometry, and X-ray photon-electron spectroscopy. It is suggested that the state of specific active sites on the electrode surface and the oxygen transfer activity at the electrode/electrolyte interface affect the performance of anodes with different compositions.