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.

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.

PbO2-CeO2 nanocomposite electrodes were prepared by pulse reverse electrodeposition in the lead nitrate solution containing CeO2 nanoparticles. The effect of pulse reverse electrodeposition parameters, such as reverse pulse frequency, reverse peak current density and reverse duty cycle, on the content of CeO2 nanoparticles in the PbO2-CeO2 nanocomposite electrodes was investigated. The SEM and XRD tests show that PbO2-CeO2 nanocomposite electrodes possess finer grain size than PbO2-CeO2 nanocomposite electrodes (P) by pulse electrodeposition and PbO2-CeO2 nanocomposite electrodes (D) by direct current electrodeposition. The service life of PbO2-CeO2 nanocomposite electrodes can reach 285 h, which is 1.3 times longer than that of PbO2-CeO2 electrodes (P), and 2.3 times longer than that of PbO2-CeO2 electrodes (D). The electrochemical measurements show that PbO2-CeO2 nanocomposite electrodes possess highest oxygen evolution overpotential and largest electrochemical active surface area among these electrodes. The electrocatalytic property of PbO2-CeO2 nanocomposite electrodes was examined for the electrochemical degradation of methylene blue (MB). The bulk electrolysis shows that PbO2-CeO2 nanocomposite electrodes exhibit the highest COD removal efficiency and lowest energy consumption, which can be ascribed to the highest oxygen evolution overpotential, largest electrochemical active surface area and highest CeO2 content.

The influence of cerium on lead dioxide electrodeposition process on a glass carbon electrode (GCE) from lead nitrate solution was studied by cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS). Cerium exhibit an inhibition effect on the lead dioxide electrodeposition process. Instantaneous nucleation mechanism can be found for lead dioxide electrodeposition according to Scharifker-Hills' model with three-dimensional growth, which is not influenced by the addition of cerium. The morphology and structure of Ce-doped PbO 2 electrodes were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that the adulteration of cerium can greatly decrease grain size and make the films more compact. Accelerated lifetime tests demonstrate that the adulteration of cerium can highly lengthen the service life of Ce-doped PbO 2 electrode in its practical application. Methylene blue degradation experiments reveal that the Ce-doped PbO 2 electrodes possess excellent electrocatalytic activity.

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