Covalent organic framework-based porous ionomers for high-performance fuel cells.

Area of Science:

• Electrochemistry
• Materials Science
• Nanotechnology

Background:

• High platinum (Pt) loadings are required for efficient fuel cells, but this increases cost.
• Mass transport resistance near catalyst surfaces limits fuel cell performance.
• Optimizing the catalyst layer's microenvironment is crucial for improving power density and durability.

Purpose of the Study:

• To reduce platinum loadings in fuel cells while maintaining high power density and durability.
• To tailor the three-phase microenvironment of fuel cell catalysts.
• To enhance proton and oxygen transport within the catalyst layer.

Main Methods:

• Incorporation of ionic covalent organic framework (COF) nanosheets into Nafion ionomer.
• Optimization of ionomer properties to improve the microenvironment.
• Characterization of mesoporous apertures and sulfonate group distribution.
• Testing fuel cell performance with tailored catalyst layers.

Main Results:

• The tailored ionomer with COF nanosheets facilitated proton transfer and oxygen permeation.
• Mass activity of Pt increased by 1.6 times.
• Peak power density of the fuel cell increased by 1.6 times.
• The strategy proved effective with various Pt loadings and commercial catalysts.

Conclusions:

• Ionic covalent organic framework (COF) nanosheets effectively optimize the fuel cell catalyst microenvironment.
• This approach allows for significant reduction in platinum loading without sacrificing performance.
• The developed strategy offers a pathway to more cost-effective and efficient fuel cells.