Iron-based catalysts with improved oxygen reduction activity in polymer electrolyte fuel cells

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Iron-based catalysts are less competitive than platinum for oxygen reduction in polymer electrolyte membrane fuel cells due to low active site density.
• Developing efficient and cost-effective alternatives to platinum is crucial for advancing fuel cell technology.

Purpose of the Study:

• To enhance the active site density of iron-based catalysts for oxygen reduction reaction (ORR).
• To achieve performance comparable to platinum catalysts in polymer electrolyte membrane fuel cells (PEMFCs).

Main Methods:

• Synthesized microporous carbon-supported iron-based catalysts.
• Utilized a synthesis route involving ball-milling phenanthroline and ferrous acetate with a carbon support, followed by dual pyrolysis (argon then ammonia).
• Characterized the catalyst structure, focusing on iron cations coordinated by pyridinic nitrogen within graphitic micropores.

Main Results:

• The optimized synthesis method significantly increased the density of active sites.
• The resulting iron-based electrocatalyst achieved a current density comparable to platinum catalysts at a loading of 0.4 mg Pt/cm².
• The catalyst demonstrated high performance at a cell voltage greater than or equal to 0.9 V.

Conclusions:

• The developed iron-based catalyst exhibits competitive performance for the oxygen reduction reaction in PEMFCs.
• The synthesis strategy effectively enhances active site density, addressing a key limitation of previous iron catalysts.
• This advancement presents a viable, potentially lower-cost alternative to platinum in fuel cell applications.