Designing a Hierarchical Porous Carbon with Optimized Nitrogen Doping for Efficient Oxygen Reduction Reaction

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Nitrogen-doped carbon materials are promising alternatives to platinum catalysts for oxygen reduction reactions.
• Current nitrogen-doped carbons still lag behind platinum/carbon (Pt/C) in terms of catalytic activity.
• Developing cost-effective, high-performance metal-free catalysts is crucial for electrochemical applications.

Purpose of the Study:

• To develop a highly reactive nitrogen-doped hierarchical porous carbon catalyst.
• To investigate the synthesis strategy involving zinc acetate and amino-rich precursors.
• To evaluate the catalyst's performance in oxygen reduction reactions and zinc-air batteries.

Main Methods:

• Primary pyrolysis of zinc acetate and amino-rich reactants.
• Utilizing a hard template method to create mesoporous structures.
• Incorporating zinc-nitrogen (Zn-N_x) structures within the porous carbon framework.
• Electrochemical testing of the catalyst for oxygen reduction reaction (ORR) and in zinc-air batteries.

Main Results:

• The synthesized catalyst, Zn(OAc)₂ -DCD/HPC, exhibits a high half-wave potential of 0.909 V vs. RHE for ORR, surpassing commercial Pt/C (0.872 V vs. RHE).
• Zinc-air batteries using Zn(OAc)₂ -DCD/HPC as cathode achieved a peak power density of 198 mW cm^-2, exceeding that of Pt/C (168 mW cm^-2).
• The strategy effectively optimized hierarchical porous structure and nitrogen doping, leading to enhanced catalytic activity.

Conclusions:

• The developed method successfully created highly active nitrogen-doped hierarchical porous carbon.
• The catalyst shows significant potential as a metal-free alternative to platinum for oxygen reduction and energy storage.
• This approach offers new avenues for designing advanced metal-free catalysts.