The Cathodic Partial Reaction. Kinetic Scheme

Metal ions in a solution for electroless metal deposition have to be, in general, complexed with a ligand. Complexing is necessary in order to prevent formation of metal hydroxide, for example Cu(OH)2, in the electroless copper deposition. One of the fundamental problems in the electrochemical deposition of metals from complexed ions is the problem of electroactive (charged) species. The electroactive species may be complexed or noncom-plexed metal ion [1]. In the first case, the kinetic scheme of the process of metal deposition is one of simple charge transfer. In the second case, the kinetic scheme is that of charge transfer preceded by the dissociation of the complex. The mechanism of the second case involves a sequence of at least two basic elementary steps  

charge transfer from the catalytic surface to the electroactive species. 

Electroactive species Mz+ are formed in the first step by the dissociation of the complex [Uhx]z+xP 

from the kinetic aspects, the cathodic partial reaction is an electrochemical reaction, Eq. (51), which is preceded by a chemical reaction, Eq. (50). 

usually proceeds in at least two elementary steps (like the cathodic partial reaction) the formation of the electroactive species and charge transfer. 

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