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Quantitative Understanding of Ionic Channel Network Variation in Nafion with Hydration Using Current Sensing Atomic
Osung Kwon1, Jihoon Lee2, Hyungju Son2
1Faculty of Science, Tabula Rasa College, Keimyung University in Seongseo, Daegu 42601, Republic of Korea.
Polymers
|March 13, 2024
Summary
This study quantifies how hydration affects ionic channels in proton exchange membranes (PEMs) using current sensing atomic force microscopy (CSAFM). A new method, the number of protons moving through the ionic channel network (NPMI), accurately reflects changes in PEM conductivity.
Area of Science:
- Materials Science
- Electrochemistry
- Nanotechnology
Background:
- Proton exchange membranes (PEMs) are critical for proton-exchange membrane fuel cells (PEMFCs).
- PEM performance relies on hydration-induced ionic channel networks.
- Current sensing atomic force microscopy (CSAFM) offers sub-nano resolution for mapping conductance and morphology.
Purpose of the Study:
- To quantitatively characterize ionic channel network variations in Nafion membranes due to hydration.
- To develop a novel method for interpreting CSAFM images of PEMs.
Main Methods:
- Utilized CSAFM to analyze Nafion membranes under varying relative humidity (RH) conditions.
- Created a nano-sized PEMFC using a CSAFM Pt-coated tip and Nafion.
- Derived the number of protons moving through the ionic channel network (NPMI) from CSAFM data.
Main Results:
- Morphological changes and surface roughness of the PEMFC were analyzed at different RH levels.
- Statistical analysis of CSAFM images provided insights into ionic channel behavior.
- The NPMI method showed good agreement with experimental proton conductivity changes.
Conclusions:
- A quantitative method was developed to understand hydration-induced ionic channel network variations in PEMs.
- The NPMI calculation offers a reliable approach for interpreting CSAFM data.
- This method provides a new tool for characterizing PEM morphology and performance.
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