Pt current collectors artificially boosting praseodymium doped ceria oxygen surface exchange coefficients

Abstract

The chemical oxygen surface exchange coefficient (k_chem) values used to quantify and rank oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) catalyst performance for high-temperature, oxygen-exchange-enabled devices (such as Solid Oxide Fuel Cells, Solid Oxide Electrolysis Cells, oxygen sensors, etc.) are often determined electrically, with the aid of precious metal current collectors. However, the curvature relaxation (κR) and Time-of-Flight Secondary Ion Mass Spectroscopy (ToF-SIMS) analyses performed here on Pulsed Laser Deposited thin films of the oxygen exchange catalyst Pr_0.1Ce_0.9O_2−x (PCO) show that unpolarized platinum current collectors dramatically improve the k_chem of Si-contaminated PCO by reducing the Si concentration at the PCO surface and/or diffusing into the PCO; even for PCO thin films only exposed to mild temperatures of 500 °C. This suggests that precious metal current collectors are likely responsible for some of the large k_chem variation reported in the literature for “identical” materials tested under “identical” conditions.