Preparation And Properties Of PbO₂-CeO₂ Electrodes By Electrodeposition

Ce-doped PbO₂ electrodes were prepared by electrodeposition method and the influence of cerium on physicochemical properties and electrodeposition process of lead dioxide electrodes were studied. The grains of PbO₂-CeO₂ electrodes become smaller and more compact with the increase of Ce content, the PbO₂-CeO₂(Ce³⁺=3mmol/L) electrodes had the smallest grain size of 16.2 nm, the atomic percentage of cerium is 0.70%, displayed the longest lifetime（74 h） by stability experiment, 4times longer than the pure lead dioxide electrode, and the oxygen evolution potential by the linear polarization curves is 1.77 V, which suggested PbO₂-CeO₂ electrodes were much more suitable for the degradation of organics. The influence of cerium on lead dioxide electrodeposition process was studied by cyclic voltammetry（CV）,chronoamperometry（CA） and electrochemical impedance spectroscopy（EIS）,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. But with the increase of the concentration of cerium ions in the bath, the more positive Eonset by CV, the smaller maximum current density and the longer corresponding time by CA, and the bigger radius by EIS, which suggested a remarkable inhibition effect of cerium ions on the lead dioxide electrodeposition.PbO₂-CeO₂ nanocomposite electrodes were prepared by the electrodeposition method in the lead nitrate solution containing CeO₂ nanoparticles and the influence of CeO₂ nanoparticles on physicochemical properties of lead dioxide electrodes were researched. CeO₂ content in the PbO₂-CeO₂ nanocomposite electrodes reaches 8.79%（ At%） from lead nitrate solution containing 50 mmol/L CeO₂ nanoparticles with current density at 30 mA/cm2 and stirring rate at 180 rpm and the temperature at 30℃,12 times longer than the PbO₂ electrodes. The service life of PbO₂-CeO₂ nanocomposite electrodes reach to 135 hours, which is 2 times（4 times） longer than that of PbO₂-CeO₂ electrodes（PbO₂ electrodes）. PbO₂-CeO₂ nanocomposite electrodes had higher oxygen evolution potential which reduced the probability of adverse reactions.The results of the degradation of Malachite Green（MG） indicate that MG and COD removal efficiency of PbO₂-CeO₂ nanocomposite electrodes reach 95.37% and69.36%, respectively, after 90 min electrolysis at current density of 30mA/cm2 at initial 30 mg/L MB concentration at electrolyte pH of 5 in 0.20 mol/L Na2SO4 supporting electrolyte solution, and the degradation of MG follows pseudo-first-order kinetics. PbO₂-CeO₂ nanocomposite electrodes exhibit excellent electrocatalytic properties, higher resistance to passivation, higher recycling capacities and excellent stability during the electrochemical degradation of MB by CV and the recycled experiment. Compared with two other electrodes showed higher MG and COD removal efficiency and higher instantaneous current efficiency and Lower power consumption with MG degradation at the best process conditions. The experimental results demonstrate that PbO₂-CeO₂ nanocomposite electrodes possesses the excellent electrocatalytic properties and show great potential applications in the treatment of organic wastewater.