Effect of electrode material on the oxidation of H-2 at the metal-Sr0.995Ce0.95Y0.05O2.970 interface

The effect of electrode material on the electrode kinetics of a metal-proto n conductor interface has been investigated in a quasi point-contact config uration for four metals: Ni, Ag, Au and Pt. The current-voltage behaviour d epends on the nature of the electrode, the hydrogen partial pressure and on temperature. For all systems studied, the anodic part of the polarisation curves displayed limiting current behaviour. For Pt at low anodic polarisat ion, an additional process determines the overall reaction rate. The appare nt reaction order (q(app)) is found to be strongly dependent on electrode t ype, suggesting that the reaction mechanism is decisively determined by the electrode, rather than by electrolyte surface. The electrocatalytic activi ty of the metal tested has been classified according to the limiting curren t density in a humidified atmosphere of N-2-1% H-2. The highest i(lim) has been detected for Ni, followed by Pt, An and Ag. (C) 2000 Elsevier Science B.V. All rights reserved.