New insights into proton surface mobility processes in PEMFC catalysts using isotopic exchange methods

Area of Science:

• Catalysis
• Materials Science
• Electrochemistry

Background:

• Proton-exchange membrane fuel cells (PEMFCs) require efficient catalyst support materials for optimal performance and durability.
• Understanding surface chemistry and adsorption phenomena is crucial for developing advanced catalyst supports.

Purpose of the Study:

• To analyze the surface chemistry and adsorption/desorption/exchange behavior of PEMFC catalyst supports.
• To investigate the role of surface functional groups on catalyst support performance using probe molecules.
• To guide the development of tailor-made support materials with enhanced properties.

Main Methods:

• Utilized H2, D2, and CO as probe molecules to study adsorption processes.
• Employed spectroscopic techniques: X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR).
• Conducted temperature-programmed desorption (TPD) coupled with mass spectrometry (MS) to analyze desorbed products.

Main Results:

• Detected sulfonic groups on the vulcanized carbon black catalyst support surface.
• Demonstrated that hydrophilic sulfonic groups facilitate proton surface mobility.
• Observed enhanced proton exchange with Pt-adsorbed deuterium, even with adsorbed CO present.

Conclusions:

• Sulfonic groups on carbon supports play a vital role in enhancing proton transfer.
• These findings are relevant for characterizing catalysts using adsorption probes.
• Informs the design of novel surface-modified carbon supports for improved PEMFC efficiency and stability.