Operando characterisation of the impact of carbon monoxide on PEMFC performance using isotopic labelling and gas analysis

Impurities in hydrogen can have a detrimental effect on the performance of polymer electrolyte membrane fuel cells (PEMFCs) used in automotive applications. However, the establishment of reliable threshold limits for each impurity is hampered by a lack of information on the distribution and speciation of impurities within the cell, including the impact of internal reactions and gas crossover. Here we describe a novel operando method for detailed investigation of the impact of impurities on a single cell PEMFC, using a combination of isotopic labelling and measurement of gas composition at the anode exhaust via Gas Chromatography – Methaniser with Flame Ionisation Detector (GC-Methaniser-FID) and Selected Ion Flow Tube – Mass Spectrometry (SIFT-MS). We demonstrate the utility of this approach in the study of the impact of internal air bleed on carbon monoxide (CO) poisoning, enabling quantification of the surface coverage of CO on the anode catalyst as a function of cathode back-pressure. This technique shows great promise as a diagnostic tool for the investigation of the impact of a wide range of impurities at stack level (e.g. hydrocarbons, ammonia, halogenated compounds).