Of Ceo <sub>, 2 </ Sub> Nanopowder Electrochemical Preparation And Formation Mechanisms

Nanometer cerium(IV) oxide (CeO2) powder was prepared by means of electrochemical method. The powders were charactered through X-ray diffraction(XRD) and transmission electron micrograph(TEM). CeO2 powders in different ways and preparation technics were compared.Nanocrystalline CeO2 were prepared by means of electrochemical method. The powders were analyzed by using XRD and TEM. It showed that the synthesized CeO2 was cubic in structure and CeO2 particles were basically spherical in shape. CeO2 powder was formed at both cathode and anode.Current efficiency can be enhanced when the concentration of O2 in electrolyte is enhanced. The lower the current density, the higher the current efficiency. The current efficiency also change with the concentration of solution. From the experiment ,the better preparation condition is as follows: concentration of Ce(NO3)3 solution is 0.5 mol/L,value of pH is above 5.0 and there are enough O2.CeO2 powder was prepared using cerous nitrate and ammonium nitrate as raw material and air as cathode. Several factors, such as time, current density and pH were analyzed. The optimum preparation conditions are as follows: the concentration of cerous nitrate and ammonium nitrate is 0.5mol/L, and current density is 0.025A/ cm2.The electrochemical behavior of oxygen in the system of Ce(NO3)3 was studied by means of linear- voltammetry and cyclic-voltammetry. The results show that O2 is reduced on the electrode surface where the pH value grow up and CeO2 films form. The reduction of oxygen is proved further through adding H2O2 to the system of Ce(NO3)3 in cyclic-voltammetry study. According to rotating-disc electrode study, it is certain that O2 is reduced by four-electron-step in Ce(NO3)3 system.