Electrochemical Phase Formation of electroactive and nanostructured PbO2 from Acetate Media: Insights into Nucleation, Growth, and Interfacial Mechanisms

The electrochemical phase formation of PbO 2 from acetate media was investigated by cyclic voltammetry, potentiostatic current transient analysis, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The cyclic voltammetry response revealed a progressive evolution of the electrochemical interface from a bare glassy carbon electrode to a PbO 2 -covered surface, accompanied by the appearance of new redox features associated with the growing oxide film. Potentiostatic current density transients exhibited the characteristic behavior of progressive two-dimensional nucleation and growth during the initial stages of deposition, followed by continued growth on the previously formed PbO 2 layer. A comprehensive kinetic model was developed by considering the simultaneous contributions of precursor adsorption, oxidation on the uncovered substrate, progressive two-dimensional nucleation and growth, and oxidation on the PbO 2 -covered surface. The proposed model successfully reproduces the complete experimental current transients over the entire deposition period and provides quantitative kinetic parameters describing each stage of the electrocrystallization process. SEM observations revealed homogeneous nanostructured cauliflower-like PbO 2 deposits composed of coalesced nano-sized crystallites, in excellent agreement with the kinetic analysis. The proposed methodology provides a general framework for describing anodic electrochemical phase formation processes and may be extended to other oxide-film electrodeposition systems that comprise evolving electrochemical interfaces.