Oxygen reduction on CrO2 bonded to a proton-exchange membrane

✍ Scribed by R. Manoharan; J.B. Goodenough

• Book ID: 103065375
• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 414 KB
• Volume: 40
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(94)00276-7

✦ Synopsis

Oxygen

reduction at a gas-fed, porous CrO, electrode bonded to a Dow Development Fuel Cell Membrane was measured at various values of pH. Bonding of the CrO, to the membrane stabilizes the oxide. The activity for the reaction is strongest at pH = 14 and decreases monotonically with pH until it is completely suppressed in the range pH = 0 to pH = 3.94; it reappears for pH < 0. The pH of zero charge (isoelectric point) for CrO, is 2.59. The data are interpreted in terms of an initial outer-sphere reaction followed by a surface exchange reaction that is rate-limiting.

A change of the active site from C?+OH-at high pH to Cr"+OH-at pH < 0 is proposed; protonation of Cr3+OH-to Cr3+OHz suppresses the reaction on this site at pH < 3.94.