Interstitial nitrogen modified Rh nanocrystals for efficient and CO-resistant alkaline hydrogen oxidation...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Developing efficient electrocatalysts for hydrogen oxidation reaction (HOR) is essential for advancing anion exchange membrane fuel cells.
• Platinum-based catalysts face challenges like cost and CO poisoning in alkaline media.

Purpose of the Study:

• To prepare novel platinum-free electrocatalysts for the hydrogen oxidation reaction (HOR) under alkaline conditions.
• To enhance the activity and carbon monoxide (CO) tolerance of electrocatalysts for anion exchange membrane fuel cells.

Main Methods:

• Synthesis of nitrogen-intercalated rhodium nanocrystals on carbon support (N-Rh/C).
• Electrochemical characterization of catalyst performance for alkaline HOR.
• In situ surface-enhanced infrared absorption spectroscopy (SEIRAS) to probe reaction intermediates.
• Density functional theory (DFT) calculations to understand reaction mechanisms.

Main Results:

• N-Rh/C nanocrystals exhibit high activity and CO tolerance for alkaline HOR.
• Simultaneous electron-deficient and electron-rich Rh sites were created by nitrogen intercalation.
• Interstitial nitrogen suppresses CO adsorption on electron-deficient sites, enhancing CO resistance.
• Enhanced OH adsorption on electron-rich sites promotes water network formation and accelerates HOR kinetics.

Conclusions:

• Nitrogen intercalation in Rh nanocrystals is an effective strategy for developing advanced platinum-free HOR electrocatalysts.
• The dual-site mechanism involving modified electronic properties of Rh is key to achieving high performance and CO tolerance.
• N-Rh/C catalysts show significant potential for practical application in anion exchange membrane fuel cells.