MECHANISTIC ASPECTS OF OXYGEN ELECTROCHEMISTRY.

Various pathways for the electroreduction of O//2 and the corresponding electrocatalyst requirements are discussed. For the four-electron overall reduction of O//2 with solution phase peroxide as an intermediate, these requirements include strong interaction of oxygen species with the catalyst in a manner that promotes O-O bond cleavage and the proper redox potentials for the catalyst and its oxygen species adducts. Recent fundamental developments are reviewed with emphasis on the transition metal macrocyclic catalysts.