PEMFC Performance Recovery from Air Pollutants Contamination
Abstract
Air pollution is a challenge that impedes proton exchange membrane fuel cell (PEMFC) commercialization. Many potential contaminants were studied with single cells and accelerated or long-term tests. These airborne contaminants cover a wide range of organic functional groups and inorganic compounds, including unsaturated hydrocarbons (alkenes, alkynes, and aromatics) and O (CO, alcohols, ketones, aldehydes, ethers, and esters), N (nitriles, ammonia, NOx), S (SO2, H2S, and COS), and halogen (halocarbons and HCl) species. In-situ and ex-situ studies indicated that contaminants adsorb on a Pt surface, compete with oxygen for sites, and may inhibit the oxygen reduction reaction (ORR). N compounds also showed an ionic conductivity effect, which was associated with an ammonium intermediate that replaces the proton in the catalyst layer ionomer and membrane. Cell performances showed that most catalyst and membrane contamination effects are mitigated by neat air operation with the exception of S and halogen species. These latter contaminants in the gas phase permeate through the electrolyte film to the catalyst surface, and are converted into anions, such as SO4 2 - and X-. Anions remain at the interface between the electrolyte film and the catalyst surface, and their subsequent removal is difficult due to repulsive effects associated with the ionomer (Donnan exclusion).
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Sep 01, 2019
- Source ID
- 10.1149/ma2019-02/33/1493
Entities
People
- Jean St-pierre
- Yunfeng Zhai