Dual-role phytic acid etching induces shell-in-shell Fe₂P/N,P-codoped carbon nanoboxes for oxygen reduction

Area of Science:

• Electrocatalysis
• Materials Science
• Energy Storage

Background:

• Developing efficient non-platinum electrocatalysts is crucial for advancing energy conversion technologies.
• Metal-organic frameworks offer tunable structures for catalyst design but require optimized synthesis strategies.

Purpose of the Study:

• To design and synthesize a high-performance non-platinum carbon electrocatalyst for oxygen reduction reactions (ORR).
• To investigate the catalytic activity and stability of the novel catalyst in zinc-air batteries.
• To elucidate the structure-activity relationship using computational methods.

Main Methods:

• A shell-in-shell catalyst (CZIF-PA-Fe2P/NC) was synthesized using phytic acid (PA) etching and secondary pyrolysis of ZIF-8.
• The catalyst's performance was evaluated for ORR and in zinc-air battery applications.
• Density functional theory (DFT) calculations were performed to understand the electronic properties and reaction mechanisms.

Main Results:

• The CZIF-PA-Fe2P/NC catalyst exhibited an excellent ORR half-wave potential of 0.914 V with high stability (96.73% retention over 30 h).
• Zinc-air batteries assembled with this catalyst showed a peak power density of 157.58 mW cm⁻² and a specific capacity of 795.76 mAh g⁻¹.
• DFT calculations indicated synergistic electronic modulation between Fe2P and N,P-codoped carbon, optimizing intermediate adsorption and reducing the rate-determining step barrier.

Conclusions:

• The phytic acid-assisted synthesis strategy is effective for creating advanced non-noble metal carbon electrocatalysts.
• The developed catalyst demonstrates competitive performance compared to platinum-based catalysts for energy storage applications.
• This work provides a new paradigm for designing cost-effective and high-performance electrocatalysts derived from metal-organic frameworks.