Electrocrystallization of lead dioxide: Influence of early stages of nucleation on phase composition

It has been revealed that coatings obtained from methanesulfonate bath at investigated conditions (10 mA cm(-2); pH = 1.0) are almost entirely composed of alpha-phase. It was found that the gradual transition from alpha- to beta-phase in the coating occurs in the presence of additives in deposition electrolytes. It was proposed to use charge coming on the formation of nuclei as the correlation parameter to predict the phase composition of obtained lead dioxide deposits. Electrocrystallization of PbO2 begins with the formation of a monolayer on the electrode surface, then the formation and growth of three-dimensional nuclei takes place. The simultaneous formation of alpha and beta phases results in the presence of two linear areas on the plot of (j-j(1))(1/3) vs. time for the progressive growth of crystals. The formation of one phase is noticeably lagged behind the other. At layer-by-layer crystallization and significant lagging of one of phases may occur ingesting of growing centers of one phase by another. The type of lagging phase depends on the nature of electrolyte: for nitrate bath it is beta, for methanesulfonate - alpha. (C) 2015 Elsevier B.V. All rights reserved.