Effects of copper cation and acetate anion on the growth of PbO 2 on a SnO 2/Ti substrate

Abstract

The effects were examined of copper(II) cations and acetate anions on the nucleation, growth and electrochemically active surface area of lead dioxide on a SnO 2/Ti electrode. The nucleation rate of electrodeposited lead dioxide was greater in the presence of Cu(II), but smaller in the presence of acetate anions when compared with that of pure PbO 2. The growth rate of the nuclei of PbO 2 was greater for acetate-doped PbO 2 but it was smaller for Cu(II)-modified PbO 2 in comparison with pure PbO 2. The acetate-doped PbO 2 was grown in the form of hemispheres, whereas the Cu(II)-modified PbO 2 was in the form of multi-sided pyramids whose growth axes are directed towards the center of the sphere. The average size of crystal aggregates for electrodeposited lead dioxide became enlarged in the presence of Cu(II). The morphology of the PbO 2 film was smooth in appearance in the presence of acetate anions. The growth of PbO 2 on the SnO 2/Ti substrate was demonstrated not to be an instantaneous process, but is preceded by progressive nucleation with preferential island growth. PbO 2 doped with the acetate anion resulted in a significant increase of the electrochemically active surface area ( Q *); by contrast, values of Q * for lead dioxide modified with Cu(II) decreased.