Resolving optimal ionomer interaction in fuel cell electrodes via operando X-ray absorption spectroscopy

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Proton exchange membrane fuel cells (PEMFCs) are crucial for clean energy.
• Understanding catalyst support interactions with ionomers is vital for PEMFC electrode performance.
• Local transport limitations at the catalyst surface impact overall efficiency.

Purpose of the Study:

• To investigate the influence of carbon support properties on ionomer-catalyst interactions in PEMFC electrodes.
• To correlate these interactions with the performance of oxygen reduction electrocatalysts.
• To identify optimal carbon support structures for enhanced fuel cell performance.

Main Methods:

• Synthesis of Pt/C electrocatalysts using the polyol method with varied carbon supports (Vulcan, Ketjenblack, biomass-derived mesoporous carbon).
• Evaluation of catalyst performance in a gas diffusion electrode configuration.
• Operando X-ray Absorption Spectroscopy (XAS) combined with gas sorption analysis to probe ionomer-catalyst interactions.

Main Results:

• Significant variations in ionomer-catalyst interactions were observed across different carbon supports.
• Pt/C catalysts supported on biomass-derived ordered mesoporous carbon exhibited the highest performance.
• Operando XAS and gas sorption analysis confirmed the beneficial effect of mesopores on ionomer-catalyst interactions at molecular and structural levels.

Conclusions:

• The presence of mesopores in carbon supports is critical for optimizing ionomer-catalyst interactions.
• Biomass-derived ordered mesoporous carbon offers a promising support material for advanced oxygen reduction electrocatalysts.
• Tailoring carbon support morphology can significantly improve proton exchange membrane fuel cell electrode efficiency.