A highly durable CoO/N-doped graphitized-nano-diamond electrocatalyst for oxygen reduction reaction

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• The oxygen reduction reaction (ORR) is crucial for fuel cell efficiency.
• Developing highly durable ORR catalysts remains a significant challenge.
• Existing catalysts often suffer from degradation, limiting fuel cell lifespan.

Purpose of the Study:

• To synthesize and characterize a novel, highly durable catalyst for the oxygen reduction reaction.
• To investigate the catalytic activity and stability of the new material.
• To evaluate the potential of the catalyst in energy storage devices like Zn-air batteries.

Main Methods:

• Hydrothermal synthesis followed by heat treatment to prepare porous cobalt oxide microspheres on nitrogen-doped graphitized-nano-diamond (CoO/N-GND).
• Characterization of the catalyst's structure, surface area, and composition.
• Electrochemical testing to evaluate ORR activity, methanol tolerance, and long-term stability through cyclic voltammetry and other electrochemical techniques.
• Performance evaluation of the catalyst as a cathode in a Zn-air battery.

Main Results:

• The synthesized CoO/N-GND catalyst exhibited a high specific surface area, exposing more active Co2+ sites.
• Nitrogen doping significantly enhanced the catalytic activity.
• The nano-diamond support provided excellent electronic conductivity and stability.
• The catalyst achieved a half-wave potential of 0.82 V (vs. RHE), comparable to Pt/C (0.85 V), with excellent methanol tolerance.
• Demonstrated remarkable stability, showing minimal activity loss after 5000 cycles.

Conclusions:

• Porous CoO/N-GND is a highly durable and active catalyst for the oxygen reduction reaction.
• The combination of porous cobalt oxide, nitrogen doping, and nano-diamond support is effective in enhancing catalyst performance and longevity.
• The catalyst shows promising application potential as a cathode material for Zn-air batteries, highlighting an innovative approach for designing durable catalysts.