Study On The Preparation And Electrocatalytic Performance Of PbO₂ Electrode Modified By Carbon Nanotubes Based On Three-dimensional Porous Titanium Substrate

In present work, the main research content was the lead dioxide electrode modification, using the porous titanium plate and carbon nanotubes to modified electrode, and studying the electric catalytic oxidation degradation of pollutants. The main contents and results are summarized as follows.Firstly, porous Ti/SnO2-Sb2O3-CNT/PbO2 electrodes were successfully fabricated by using thermal decomposition technique and electro-deposition technologies. Experimental characterization of the sample, including scanning electron microscope (SEM), energy dispersive spectrum (EDS), X-ray diffraction (XRD), cyclic voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS) and accelerated life time test was performed to evaluate the effect of CNT-doped SnO2-Sb2O3 intermediate layer on PbO2 electrode. The results showed that CNT could be doped into the SnO2-Sb2O3 intermediate layer by thermal decomposition. Compared with porous Ti/SnO2-Sb2O3 substrate, CNT-doped induced the substrate surface forming a fibrous structure, it means that porous Ti/SnO2-Sb2O3-CNT substrate would provide more active sites for PbO2 deposition and could make a compact and fine surface coating. Besides, the CNT modified electrode had higher active surface area and higher electrochemical activity than without CNT doped. The life of porous Ti/SnO2-Sb2O3-CNT/PbO2 (296h) was 1.38 times as much as that of porous Ti/SnO2-Sb2O3/PbO2 electrode (214h). Electro-catalytic oxidation of phenol and hydroxyl radical (·OH) generation capacity was studied to evaluate the electrochemical oxidation ability in environment science. Porous Ti/SnO2-Sb2O3-CNT/PbO2 electrode displayed not only excellent electro-catalytic performance but also low energy consumption using phenol as a model organic pollutant. The porous Ti/SnO2-Sb2O3-CNT/PbO2 electrode has higher kinetic rate constant and COD, which is 1.73 and 1.09 times those of the porous Ti/SnO2-Sb2O3/PbO2 electrode, separately.Secondly, a novel CNT-doped PbO2 electrode with porous titanium as substrate (porous Ti/SnO2-Sb2O3/CNT-PbO2) was successfully prepared. The microstructure of modified electrodes was characterized by SEM, EDS, XRD. In contrast with the PbO2 electrode, CNT-doped PbO2 displayed a more compact surface with a smaller particle size of crystal. The electrochemical properties of modified electrodes were characterized by LSV, electrochemical active surface area, EIS and Chronoamperometric. Compared with pure PbO2 and CNT-PbO2, the results showed that CNT-doped provided higher oxygen evolution potential, larger surface area and active sites, electrochemical oxidation ability for electrochemical reaction system. In addition, the fluorescence experimental indicated that CNT-doped PbO2 significantly increased the generation for hydroxyl radical (-OH). The electro-oxidation process of several typical organic dye pollutants (Rhodamine B, Methylene Blue, Amido Black 10B) demonstrated that CNT-doped PbO2 had a superior electrochemical oxidation ability, mineralization current efficiency and lower energy consumption.Finally, the oxidation process of Acid Black 10B was studied by porous Ti/SnO2-Sb2O3/ CNT-PbO2 electrode in four aspects (electrolyte concentration, current density, initial pH and initial concentration of Acid Black 10B). The results showed that the concentration of the electrolyte under conditions of 0.06 mol L-1,40 mA cm-2 current density, initial pH=11 and 40 mg l-1 the initial concentration, the degradation of Acid Black 10B effect is best.