The Lead Anode in Alkaline Solutions I. The Initial Oxidation Processes

The initial reactions occurring at a Pb anode in alkaline solutions have been investigated using cyclic voltammetry and steady-state and transient potentiostatic methodologies. It has been found that the first step in the reaction is the for-mation of a PbOH surface intermediate, followed by the deposition of a thin Pb(OH)2 film on the Pb surface. A major portion of this film dissolves to form Pb(OH)3- and the measured Tafel slope of 27 mV/decade of current density is consist-ent with the dissolution step being the rate-determining step. With the use of the rotating ring disk electrode technique, in which the disk current is separated into that due to the formation of an insoluble surface product and that due to a dissolu-tion reaction, it was found that some of the Pb(OH)2 film dehydrates to form a thin PbO film. At more positive potentials, further PbO film growth occurs, but by a nucleation and growth mechanism. Although there is a very large body of l iterature con-cerning the electrochemical behavior of lead in acid so-lutions (1-5), very few papers have been concerned with the behavior of lead in alkaline solutions (6-11). The work carried out to date in alkaline solutions has utilized only steady-state approaches and has focused primarily on P