Oxygen electroreduction reaction intermediate species

The Most Likely Intermediate Species Involved in the Oxygen Electroreduction Mechanism on Pt(111) and Pt( 100) Clusters The adsorption configuration study for the oxygen adsorbates on platinum, described above, provides the possibility of exploring further mechanistic aspects of the oxygen electroreduction, particularly in relation to the possible species involved in the reaction that account for the different behavior of Pt(l 11) and Pt(100) electrode surfaces. 

Platinum/ platinum family metals/ and silver are classified in the second group. The oxygen electroreduction on these metals occurs both directly to water and via intermediate formation of hydrogen peroxide. The hydrogen peroxide formed in the parallel reaction is decomposed by chemical or electrochemical mechanisms. The relation between the rates of these processes depends in a complicated way on the nature of the metal, the potential, the coverage of the electrode by the chemisorbed species, and their adsorption character. The polarization curves are characterized by a single wave with a limiting current close to the diffusion current for the four-electron process. 

In a successive reaction, two or more intermediate steps occur in series, that is, an intermediate produced in the first step is reacted in the second. If more than two intermediate steps are involved, then the species produced in the second step reacts in the third step. An example of this successive reaction of relevance to fuel cells is the electroreduction of oxygen to water reaction ... 

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