Preparation Methods On The Lead Dioxide Electrode Structure And Properties Of Impact

The anodes of PbO₂ were studied in this paper. The surface microstructure and morphology, electrochemical performance and life time of the PbO₂ anodes prepared by different methods were studied. The reaction rates and current efficiencies of the oxidation of Cr³⁺ with the PbO₂ prepared by different methods as anodes under the same experimental condition were compared.(1) The Pb/PbO₂ anode was prepared by electrolysis, the Ti/SnO₂+Sb₂O₃/PbO₂ anode was prepared by electrodeposition, and the lead oxide coatings were prepared by thermal decomposition. The surface microstructure of the PbO₂ prepared by different methods was examined by means of XRD. The experimental results show that the microstructures of the PbO₂ anodes prepared by different methods are different. The microstructure of the Pb/PbO₂ anode prepared by electrolysis is consisted of mixture ofα- andβ-phases of PbO₂; The microstructure of the Ti/SnO₂+Sb₂O₃/PbO₂ anode prepared by electrodeposition is detected mainly theβ-phases of PbO₂, and an examination of the XRD show the microstructure of lead oxide coatings prepared by thermal decomposition are Pb3O4. In addition, the microstructure of lead oxide coatings prepared by thermal decomposition are changing during electrolysis in H₂SO₄, the films of Pb3O4 are completely converted to theβ-PbO₂ after electrolysis. In addition, The surface morphology of the PbO₂ anodes prepared by different methods was examined by means of SEM. An amorphous mass with high porosity is formed in the surface of the Pb/PbO₂ anode and the morphology of the Ti/SnO₂+Sb₂O₃/PbO₂ anode prepared by electrodeposition display a blocklike structure; The SEM micrographs of the lead oxide coatings prepared by thermal decomposition showed that its morphology is sticklike structure. (2) The activity of electrocatalysts depends on the electrochemical active surface area partly. Electrochemical active surface area of PbO₂ anodes prepared by different methods was calculated. The results show that the electrochemical active surface area of PbO₂ anodes prepared by electrodeposition is the lowest. And the electrochemical active surface area of Ti/SnO₂+Sb₂O₃/PbO₂ anode prepared by thermal decomposition is higher than the anode of Pb/PbO₂. The electrochemical behavior of the PbO₂ anodes prepared by different methods was determined, the experimental results show that the peak current of the evolution of oxygen may be arranged by the following order: the anode of Ti/SnO₂+Sb₂O₃/PbO₂ prepared by thermal decomposition is higher than the anode of Pb/PbO₂ prepared by electrolysis, and the anode of Pb/PbO₂ prepared by electrolysis is higher than the anode of Ti/SnO₂+Sb₂O₃/PbO₂ prepared by electrodeposition. The lifetimes of the Ti/SnO₂+Sb₂O₃/PbO₂ anodes prepared by different methods were assessed by the accelerated lifetime test, and the experimental results show that the lifetime of Ti/SnO₂+Sb₂O₃/PbO₂ anode prepared by electrodeposition performed at 60℃and in 1.0mol/L H₂SO₄ with an anodic current density of 4.0A/cm² is 135h while the lead oxide coatings prepared by thermal decomposition is 25h.(3) The electrochemical behavior of the PbO₂ anodes prepared by different methods were studied, the experimental results show that the peak current of the evolution of oxygen decrease with increasing the concentration of Cr³⁺. Under the same experimental condition, the reaction rates and current efficiencies of the oxidation of Cr³⁺ with the Ti/SnO₂+Sb₂O₃/PbO₂ prepared by thermal decomposition as anode are higher than the Pb/PbO₂, and the Ti/SnO₂+Sb₂O₃/PbO₂ anode prepared by electrodeposition is the lowest.