In-Situ Measurement of Oxygen Partial Pressure in the Cathode Flow Field with a Hydrophilic Surface

Cathode oxygen concentration is vital for the performance of proton exchange membrane fuel cells (PEMFC). A novel method to directly detect oxygen partial pressure in the cathode flowfield has been developed utilizing fluorophore molecules which are sensitive to oxygen quenching. A platinum porphyrin based fluorophore is used with a polymer binder to form the fluorophore layer that is exposed to the cathode gas flow field in the visualization cell. In this study, poly-heptafluoro-n-butly, methacrylate-co-hexafluroisopropyl, and methacrylate (FIB polymer) were used as the binder to obtain a proper range of quenching rate. Thus, the intensity of fluorescent luminescence of this fluorophore layer covers 7 kPa to 53 kPa oxygen partial pressure concentration. Also, this material composition exhibits acceptable temperature sensitivity between 40 to 90 degrees C. The polymer binder modification described in this report enabled accurate in-situ oxygen partial pressure measurements to cover typical operating conditions of an automotive PEMFC.