Study On The Electrodeposition Mechanism Of ?-PbO₂ In High-concentration Nitrate System

The electrodeposition mechanism of ?-PbO₂ plays an important role in the development of ?-PbO₂.The related researches and reports on the traditional deposition mechanism of ?-PbO₂ are mainly concentrated in the low concentration lead nitrate system.However,with the development of ?-PbO₂ to a new structure,the concentration of lead nitrate gradually increases.However,the electrodeposition mechanism of ?-PbO₂ in high concentration nitrate system has not been reported in detail.Based on the above reasons,the electrochemical methods such as rotating disk electrode?RDE?,cyclic voltammetry,electrochemical impedance and chronoamperometry are used in this paper to study the electrodeposition process of ?-PbO₂ in high concentration nitrate system,and the kinetic parameters of the nucleation process of ?-PbO₂ are calculated.The following conclusions are obtained:In high concentration nitrate system,the electrodeposition behavior of ?-PbO₂ is the oxidation process of Pb???to Pb???.Pb²⁺combines with hydroxyl radicals in water to generate soluble products Pb?OH?²⁺and insoluble solid particles O-Pb²⁺,which are adsorbed on the electrode surface and further oxidized under the action of an applied electric field to finally generate ?-PbO₂.It is worth noting that in the process of Pb?II?to Pb?IV?,it is believed that this is the result of the common control of two reactions.And the charging and discharging process can achieve the function of activating the electrode surface,thus reducing the ?-PbO₂-shaped nuclear potential.It is clear that the transfer resistance of Pb²⁺is caused by concentration polarization,that is,concentration polarization will cause the transfer of Pb2+to be blocked,which is the biggest obstacle to the deposition of ?-PbO₂.The resistance of diffusion can obtain ?-PbO₂ structure with better corrosion resistance under appropriate conditions.The doping of ZrO₂ and WC functional particles does not change the electrodeposition process of ?-PbO₂,but increases the diffusion rate of Pb²⁺in the nucleation process of ?-PbO₂,of which WC has good electrical conductivity and obviously promotes the diffusion rate of Pb²⁺;According to Koutecky-Levich equation and Laviron equation,the relevant kinetic parameters of ?-PbO₂ nucleation process were calculated,and the relevant kinetic parameters of ?-PbO₂ deposition process were obtained.The electrodeposition mechanism of ?-PbO₂ in high concentration nitrate system was analyzed by cyclic voltammetry curve,chronoamperometry curve and electrochemical impedance spectroscopy,which were consistent with the above results.The equivalent circuit available is R?C?R?Q?R?QR?????;When the cut-off potential is greater than or equal to 1.30V,crystal nuclei are formed only after PbO₂ is deposited,and the electrodeposition of PbO₂ follows a?SH?three-dimensional continuous nucleation model.