Preparation, Characterization And Application Of A Novel High-Performance Lead Dioxide Electrode

Electrodes, which are the heart in electrochemical reaction system, are the keyfactors for causing a chemical reaction, increasing current efficiency and reducingenergy consumption. So the study of making electrodes with high electrocatalyticability has great practical significance. In this paper, a highly active PbO₂electrodemodified with Bi³⁺（Bi-PbO₂） was first prepared, however, the short service life andpoor stability were manifested in its actual application. So surfactants were used tofurther modify Bi-PbO₂electrode and the high-performance electrodes, Bi-PbO₂/PVPand Bi-PbO₂/PEG, were prepared. SEM, XPS, XRD, UV-Vis DRS, Mott–Schottky,EIS, LSV and CV were used to characterize the microstructure and electrochemicalproperties of the different modified electrodes, viz. chemical composition, oxidationstate of Bi, topography, crystalline phase, interface structure, band structure, flat bandvoltage, electrode reaction property, OER activity and effective reaction surface area.The results of EDX and XPS showed that Bi could enter into PbO₂coating in theform of Bi₂O₃and surfactants modification could increase the bismuth content. SEManalysis showed that incorporation of Bi³⁺could cause a great change in the electrodesurface morphology and surfactants modification could further diminish the electrodeparticle size. XRD analysis showed all the electrodes was also composed of β-PbO₂.Phenol degradation experiments revealed that Bi-PbO₂electrode owned a higherelectro-catalytic activity than unmodified PbO₂electrode and surfactant modificationcan further enhance it. For example, the phenol degradation ratio on Bi-PbO₂/PEGand Bi-PbO₂/PVP electrode will reach to95.6%and98.5%, respectively, at thecurrent density of100mA·cm^-2. Electrochemical performance tests indicated that themodified electrodes have larger active surface area, lower charge-transfer resistanceand higher oxygen evolution potential, and these characteristics promote theelectro-catalytic activity of the modified electrodes for organic matter decomposition.Meanwhile, accelerated lifetime tests demonstrated that surfactants modificationcould highly lengthen the service life of Bi-PbO₂electrode during its practical using which would be beneficial to its electro-catalytic property.With the rapid development of dye industry, the treatment of refractory dyewastewater has become one of the serious problems in the field of water processing.Electro-catalytic oxidation technology which is a green technology has aroused greatinterest of researchers for its particular advantage, such as high efficiency,inexpensive instruments and simple operation. In this thesis, Acid Red G and AlizarinGreen which were used respectively as representatives of azo dye and anthraquinonedye were regarded as targets and electro-catalytic oxidation technology was appliedto treat their simulated wastewater using the modified lead dioxide electrodes asanode. The effects of current density, temperature, the initial dye concentration, pHand electrolyte concentration on degradation efficiency were investigated. The resultsshowed that current density play an important decisive role in electrochemicaloxidation process, but excessive current density and temperature will promote theoxygen evolution side reaction and this will lower current efficiency and increaseenergy consumption. At room temperature, more than98%of Acid Red G (c0=100mg·L^-1, j=80mA·cm^-2, t=2h) and Alizarin Green (c0=200mg·L^-1, j=100mA·cm^-2, t=2.5h) would be removed by Electrocatalytic Oxidation Method. Kineticexperiments suggested that electro-catalytic oxidation of Acid Red G and AlizarinGreen is in accord with pseudo-first order kinetic law. What’s more, the results ofUV-Vis, FR and IR showed that the degradation of Acid Red G and Alizarin Greenwas a complex process and they were first dissolved into aromatic intermediateproducts, then further decomposed into lower organic acids and finally completelymineralized to H₂O and CO₂. Specifically, in above processes, hydroxyl radical playsa main role.