Tunable Synthesis of Porous Iron Powder From Fe-Based MOFs via Shell-Protection Strategy for Enhanced N₂...

Area of Science:

• Electrochemistry
• Materials Science
• Sustainable Chemistry

Background:

• Electrochemical nitrogen reduction reaction (NRR) is a sustainable route to ammonia production.
• Achieving high ammonia yield and Faradaic efficiency (FE) with bulk catalysts at practical current densities remains a challenge.

Purpose of the Study:

• To develop a novel iron-based electrocatalyst for enhanced NRR.
• To investigate the effect of catalyst structure and doping on NRR performance.
• To provide guidance for industrial-scale green ammonia synthesis.

Main Methods:

• Shell-protection strategy to prepare phase-pure iron powder from Fe-based metal-organic frameworks.
• Electrochemical characterization of the catalyst's NRR performance.
• Cobalt (Co) doping to further enhance catalytic activity.
• Combined experimental and theoretical analyses to understand reaction mechanisms.

Main Results:

• The prepared iron powder exhibited excellent antioxidant and acid-resistant properties.
• The iron catalyst achieved an ammonia yield rate of 120.05 µg h⁻¹ mg⁻¹ and an FE of 43.44%, a 20-fold improvement over commercial iron.
• Co-doped iron powder demonstrated a further enhanced NH₃ yield rate of 200.50 µg h⁻¹ mg⁻¹ with an FE of 56.34% at 7 mA cm⁻².
• Fe vacancies were identified as crucial for N₂ adsorption and activation.

Conclusions:

• The shell-protection strategy is effective in preparing high-performance NRR electrocatalysts.
• Co doping and Fe vacancies significantly enhance NRR activity and selectivity.
• This work offers a promising approach for developing bulk transition metal catalysts for industrial green ammonia synthesis.