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Updated: Jul 21, 2026
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In Situ Monitoring of Diffusion of Guest Molecules in Porous Media Using Electron Paramagnetic Resonance Imaging
Published on: September 2, 2016
Diffusion on a nanoparticle surface as revealed by electrochemical NMR
Y Y Tong1, E Oldfield, A Wieckowski
1Department of Chemistry, Georgetown University, Washington, DC 20057, USA.
Faraday Discussions
|September 14, 2002
Summary
Surface diffusion of carbon monoxide (CO) on platinum (Pt) and ruthenium-modified Pt electrocatalysts was studied. Higher CO diffusion activation energy correlated with increased methanol electro-oxidation current, offering insights into CO tolerance in fuel cells.
Area of Science:
- Electrochemistry
- Materials Science
- Surface Science
Background:
- Electrocatalysts are crucial for fuel cell performance.
- Understanding surface diffusion of adsorbed species is key to optimizing electrocatalyst design.
- Methanol electro-oxidation is a vital reaction in direct methanol fuel cells, often limited by CO poisoning.
Purpose of the Study:
- To investigate the surface diffusion of chemisorbed carbon monoxide (CO) on pure and ruthenium-modified platinum (Pt) electrocatalyst surfaces.
- To correlate CO diffusion dynamics with catalytic activity for methanol electro-oxidation.
- To elucidate mechanisms for enhanced CO tolerance in Pt/Ru catalysts.
Main Methods:
- Solid-state electrochemical Nuclear Magnetic Resonance (EC-NMR) spectroscopy.
- Temperature-dependent nuclear spin-spin and spin-lattice relaxation measurements.
- Analysis using a two-dimensional collision theory model.
Main Results:
- The activation energy (E) for CO surface diffusion was successfully deduced.
- A direct correlation was observed between the CO diffusion activation energy (E) and the steady-state current for methanol electro-oxidation.
- The findings suggest a link between CO mobility and catalytic efficiency.
Conclusions:
- CO surface diffusion dynamics are intrinsically linked to methanol electro-oxidation performance.
- The proposed model provides mechanistic insights into how Pt/Ru catalysts achieve improved CO tolerance.
- This research contributes to the development of more efficient and durable fuel cell electrocatalysts.
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