Oxygen exchange on platinum electrodes in zirconia cells: location of electrochemical reaction sites

• Published in: Journal of the Electrochemical Society Vol. 137; no. 1; pp. 129 - 135
• Main Authors: ROBERTSON, N. L, MICHAELS, J. N
• Format: Journal Article
• Language: English
• Published: Pennington, NJ Electrochemical Society 1990
• Subjects: 30 DIRECT ENERGY CONVERSION; 300505 > Fuel Cells > Electrochemistry, Mass Transfer & Thermodynamics; 640302 > Atomic, Molecular & Chemical Physics > Atomic & Molecular Properties & Theory; ATOMIC AND MOLECULAR PHYSICS; CHALCOGENIDES; CHARGE TRANSPORT; Chemistry; DATA; ELECTROCHEMICAL CELLS; Electrochemistry; ELECTRODES; ELEMENTS; Exact sciences and technology; EXPERIMENTAL DATA; General and physical chemistry; INFORMATION; MATERIALS; METALS; NONMETALS; NUMERICAL DATA; OXIDES; OXYGEN; OXYGEN COMPOUNDS; PLATINUM; PLATINUM METALS; POLARIZATION; POROUS MATERIALS; Properties of electrolytes: conductivity; STEADY-STATE CONDITIONS; TRANSITION ELEMENT COMPOUNDS; TRANSITION ELEMENTS; ZIRCONIUM COMPOUNDS 300503 > Fuel Cells > Materials, Components, & Auxiliaries; ZIRCONIUM OXIDES; Temperature; Porous electrode; Electrode electrolyte interface; Transition metal; Experimental study; Steady state; Transient method; Intensity potential curve; Partial pressure; Platinum; Reaction mechanism; Paste electrode; Kinetics; Chronoamperometry; Oxygen pressure
• ISSN: 0013-4651; 1945-7111
• DOI: 10.1149/1.2086347

Oxygen exchange kinetics on porous platinum electrodes in a zirconia electrochemical cell were measured at 600-800 C over a range of oxygen partial pressure of 0.00001-0.21 atmospheres. Steady-state polarisation and potential-step chronoamperometric experiments were performed. Steady-state current-voltage characteristics exhibited near-exponential behaviour at intermediate potentials and approached anodic and cathodic limiting currents at higher overpotentials. At and below 600 C, the initial decay of the current following anodic and cathodic potential steps was inversely proportional to the square root of time. This Cottrell-type behaviour indicates that the charge-transfer step in the mechanism of oxygen exchange occurs at the three-phase boundary where the electrode, electrolyte, and gas-phase intersect. 17 refs.