In-Situ Measurement of Oxygen Particial Pressure on the Surface of a Cathode GDL with Automotive Compatible Operating Conditions

Abstract

Cathode oxygen concentration is vital for fuel cell performance. In-situ measurement of oxygen partial pressure provides a method to determine the local oxygen concentration in the cathode. A novel method that uses oxygen sensitive fluorophore materials has been developed to directly measure the oxygen partial pressure in the cathode flow field during fuel cell operation. Fluorescent luminescence is sensitive to oxygen quenching as described by the Stern-Volmer equation. The oxygen quenching rate was modified to meet a desired range of oxygen partial pressure measurement. In a previous study, a fluorophore ink material with a platinum porphyrin based fluorophore dispersed in the FIB polymer was developed. This fluorophore ink material showed a sufficient level of intensity of fluorescent luminescence to cover the typical operating condition of an automotive proton exchange membrane fuel cell (PEMFC). However, this fluorophore ink material was too viscous for the surface of the gas diffusion layer (GDL) where ink material clogged the pores of the GLD and lowered the fuel cell performance. In this study, the fluorophore ink material was modified. A newly developed less viscous fluorophore ink material was confirmed that the fuel cell performance was not affected by the sprayed ink materials. Concurrently, it was confirmed that the oxygen quenching rate of this fluorophore materials were retained. The Stern-Volmer calibration enabled accurate in-situ oxygen partial pressure measurements on the surface of the cathode GDL to cover the typical operating conditions of an automotive PEMFC.