Active Sites Engineering toward Superior Carbon-Based Oxygen Reduction Catalysts via Confinement Pyrolysis

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Efficient and low-cost catalysts are crucial for oxygen reduction reaction (ORR) in metal-air batteries and fuel cells.
• Engineering active sites in carbon-based catalysts is essential for enhanced performance but remains challenging.

Purpose of the Study:

• To develop a controllable method for regulating active sites in defective carbon-based catalysts.
• To investigate the ORR performance of tailored catalysts, including metal-free N-doped carbon (NC), single Co atoms dispersed NC (Co-N-C), and Co nanoparticles-contained Co-N-C (Co/Co-N-C).

Main Methods:

• A sandwich-like confinement route was employed for catalyst synthesis.
• Synchrotron radiation-based X-ray spectroscopy was used for catalyst characterization.
• Electrochemical measurements were conducted to evaluate ORR performance.

Main Results:

• Three distinct catalysts (NC, Co-N-C, Co/Co-N-C) were controllably synthesized and identified.
• The Co/Co-N-C catalyst exhibited optimized ORR performance.
• Rich Co-Nₓ active sites and synergistic effects with metallic Co nanoparticles contributed to the enhanced performance.

Conclusions:

• The developed sandwich-like confinement route enables controllable regulation of active sites in carbon-based catalysts.
• The Co/Co-N-C catalyst demonstrates superior ORR activity, offering insights for designing efficient catalysts.
• This work provides a pathway for rationally designing advanced ORR catalysts through active site engineering.