The Preparation Of Ti/SnO₂-Sb/PbO₂Electrodes And The Modification Of Pr-doped PbO₂Layer

The electrocatalytic activity and stability of electrode is the definitive factor of electro-catalytic process. In this study, a lead dioxide electrode on titanium basal body with SnO2-Sb middle layer was made (Ti/SnO2-Sb/PbO2), and a series of praseodymium modified Ti/SnO2-Sb/PbO2(Ti/SnO2-Sb/PbO2-Pr) electrodes were synthesized by doping PbO2with praseodymium.The physicochemical properties of the electrodes were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical measurements. The degradation of4-chloro-3-methyl phenol (CMP) using Ti/SnO2-Sb/PbO2anodes was studied by monitoring the total organic carbon (TOC) removal, and the concentration of produced intermediates was tested. The effect of Pr doping on the electrocatalytic activity towards the model dye C.I. Acid Black194(AB-194) was examined in aqueous solution. The COD of AB-194was monitored during the degradation process, and the degradation mechanism was investigated by GC-MS. The effect of Pr doping towards electrode stability was studied by accelerated life test. It could be seen from characterization results that the surface composition of Ti/SnO2-Sb/PbO2and Ti/SnO2-Sb/PbO2-Pr electrodes is β-PbO2, and the surface was entirely covered. Compared to the undoped one, the Ti/SnO2-Sb/PbO2-Pr electrodes surfaces are rough and many "cracks" could be observed. The electrocatalytic activity and life time of the Ti/SnO2-Sb/PbO2electrode can be greatly improved by adding an appropriate amount of Pr into the PbO2layer, and the optimum metal doping level is5%(Pr:Pb in the plating solution). The introduction of Pr enhanced the formation of oxygen vacancies and surface hydroxyl groups, resulting in better activity and stability of the Ti/SnO2-Sb/PbO2-Pr electrode. A possible degradation pathway of CMP and AB-194during the anodic oxidation process is proposed based on hydroxyl radical attack of the organic reactant and the intermediate product test results.