A study of the catalysis of cobalt hydroxide towards the oxygen reduction in alkaline media

A cobalt hydroxide modified glassy carbon (Co(OH)(2)/GC) electrode has been fabricated by a galvanostatic electrodeposition method. The catalytic activity for the oxygen (O-2) reduction reaction (ORR) of this electrode in alkaline media is studied by cyclic voltammetry, rotating disk electrode voltammetry, and rotating ring-disk electrode voltammetry. The O-2 reduction at the Co(OH)2/GC disk electrode has been found to undergo an electrochemical process followed by sequential disproportionation of the electrochemical reduction intermediates, i.e.. superoxide anion (O-2(center dot-)) and hydrogen peroxide anion (HO2-) in 0.1 M KOH solution. The Co(OH)2 is first found to possess an excellent catalytic activity not only for the disproportionation of the O-2(center dot-) produced into O-2 and HO2- but also for that of the HO2- produced, combined with electrochemical reduction of O-2 mediated by surface functional groups at the carbon electrode surface. The Co(OH)(2) is a potential electrode material for the ORR in alkaline fuel cells and metal-air batteries. (C) 2009 Elsevier B.V. All rights reserved.