Superactivation of metal electrode surfaces and its relevance to CO sub ads oxidation at fuel cell anodes

• Published in: Journal of applied electrochemistry Vol. 31; no. 7; pp. 729 - 738
• Main Authors: Burke, L D, Horgan, M A, Hurley, L M, Nagle, L C, O'Mullane, A P
• Format: Journal Article
• Language: English
• Published: 01.07.2001
• ISSN: 0021-891X

The inhibiting effect of CO sub ads on platinum-based anodes is a major problem in the development of ambient temperature, polyelectrolyte membrane-type fuel cells. One of the unusual features of the response for the oxidative removal of the species in question is that the response observed for this reaction in the positive sweep is highly dependent on the CO admission potential, for example, when the CO sub ads is formed in the H sub ads region it undergoes oxidation at unusually low potentials. Such behaviour is attributed here to hydrogen activation of the platinum surface, with the result that oxide mediators (and CO sub ads oxidation) occurs at an earlier stage of the positive sweep. It is also demonstrated, for both platinum and gold in acid solution, that dramatic premonolayer oxidation responses may be observed following suitable preactivation of the electrode surfaces. It is suggested that the defect state of a solid electrode surface is an important variable whose investigation may yield improved fuel cell anode performance.