Surface intermediates on metal electrodes at high temperature

The mechanisms widely conceived for the O-2-reduction or H-2-oxidation reac tions in SOFC's involve intermediate O/H species adsorbed on the electrode surface. The presence of these intermediates is investigated by linear swee p voltammetry. In air at moderate temperatures (500 degrees C) Pt in contac t with YSZ is covered with adsorbed oxygen which vanishes at high temperatu re (1000 degrees C). On Ni (YSZ) a specific layer of NiO is observed above the equilibrium potential while no surface species involving hydrogen can b e identified at SOFC anode conditions. (C) 1998 Published by Elsevier Scien ce B.V. All rights reserved.