PbO 2 -CeO 2 nanocomposite electrodes were prepared by composite electrodeposition method in the lead nitrate solution containing CeO 2 nanoparticles. The composite electrodes possess 8.79 at% cerium content, which is 12 times than the Ce-doped PbO 2 electrodes (0.7 at%). The electrochemical measurements show that PbO 2 -CeO 2 nanocomposite electrodes possess higher oxygen evolution overpotential (1.98 V vs. SCE) than PbO 2 electrodes (1.51 V vs. SCE) and Ce-doped PbO 2 electrodes (1.77 V vs. SCE). The service life of PbO 2 -CeO 2 nanocomposite electrodes is 135 h, which is 1.8 times longer than that of Ce-doped PbO 2 electrodes. The malachite green (MG) and chemical oxygen demand (COD) removal efficiency of PbO 2 -CeO 2 nanocomposite electrodes reach 95.4% and 69.3%, respectively, after 90 min electrolysis in 0.2 mol L −1 Na 2 SO 4 solution containing 30 mg L −1 MG with the current density at 30 mA cm −2 and pH values at 5.0. Compared with traditional PbO 2 electrodes and Ce-doped PbO 2 electrodes, PbO 2 -CeO 2 nanocomposite electrodes possess highest COD removal efficiency and instantaneous current efficiency (ICE), and lowest specific energy consumption with MG degradation.

The three-dimensional porous structure PbO 2 electrodes (3D-PbO 2 ) were successfully prepared in the lead nitrate solution by potentiostatically electrodeposition methods using oxygen bubbles as dynamic template. The morphology and structure of 3D-PbO 2 electrodes were investigated by scanning electronic microscopy (SEM) and X-ray diffraction (XRD). Compared with the traditional PbO 2 electrodes (Flat-PbO 2 ), 3D-PbO 2 electrodes possess the three-dimensional porous structure and finer grain size. The electrochemical properties of 3D-PbO 2 electrodes were investigated by linear sweep voltammetry (LSV), cyclic voltammetry (CV) and electrochemical impedance spectrum (EIS). The 3D-PbO 2 electrodes show larger electrochemical active surface area, lower charge transfer resistance and higher oxygen evolution overpotential than Flat-PbO 2 electrodes. In the electrocatalytic degradation process of malachite green, the degradation rate constant of 3D-PbO 2 electrodes (0.05189 min −1 ) was 5.8 times than that of Flat-PbO 2 electrodes (0.00889 min −1 ).

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Electrocatalytic oxidation is a promising process for degrading toxic and biorefractory organic pollutants in wastewater treatment. Selection of electrode materials is crucial for electrochemical oxidation process. In this study, Ti/F-PbO 2 and Ti/Sb-SnO 2 electrodes were chosen to compare their electrocatalytic characterization, which were prepared by electrodeposition and thermal decomposition method, respectively. The surface morphology and crystal structure of two electrodes were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The linear polarization curves show that Ti/Sb-SnO 2 electrodes possess higher oxygen evolution overpotential than Ti/F-PbO 2 electrodes. But the stability and corrosion resistance ability of Ti/F-PbO 2 electrode was higher than that of Ti/Sb-SnO 2 electrode. The electrocatalytic activity of Ti/F-PbO 2 and Ti/Sb-SnO 2 electrodes was examined for the electrochemical oxidation of malachite green (MG). The bulk electrolysis shows that the Ti/SbSnO 2 electrodes exhibit the higher electrocatalytic activity for the degradation of MG than Ti/F-PbO 2 electrodes, and the degradation process is good fitting for the pseudo-first order reaction. The higher electrocatalytic activity of Ti/ Sb-SnO 2 electrodes can be attributed to the higher oxygen evolution overpotential.

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