Estimation of Charge-Transfer Resistivity of Pt Cathode on YSZ Electrolyte Using Patterned Electrodes

Yttria-stabilized zirconia ͑YSZ͒ electrolyte disks with patterned platinum ͑Pt͒ electrodes having different three phase boundary ͑TPB͒ lengths ͑l TPB ͒, but the same electrode-electrolyte interface area, were deposited on one of the two faces using photomicrolithography.Platinum counter electrode was applied on the other face, and a platinum wire reference electrode was positioned along the cylindrical surface.Impedance spectra under zero applied bias were obtained in oxygen partial pressures, ͑p O 2 ͒, ranging between 10 -3 and 1 atm and over a range of temperatures between 650 and 800°C.Area-specific charge-transfer resistance, R ct , was found to vary inversely with l TPB .The value of charge-transfer resistivity, ct , corresponding to the charge-transfer reaction occurring at TPB, was estimated at various temperatures and p O 2 .The R ct and ct decrease with increasing p O 2 and with increasing temperature.The activation energy for the overall charge-transfer reaction was found to vary between 0.75 eV at a p O 2 of 0.001 atm and 1.63 eV for a p O 2 of 1 atm.