Tunable Synthesis of Porous Iron Powder From Fe‐Based MOFs via Shell‐Protection Strategy for Enhanced N ₂ Electroreduction

Abstract

ABSTRACT The electrochemical nitrogen reduction reaction (NRR) offers a sustainable transformation of nitrogen (N 2 ) into highly valuable ammonia. However, achieving both a high ammonia yield and an Faradaic efficiency (FE) higher than 40% at practical current density remains challenging, particularly with bulk metal catalysts. Herein, we propose a shell‐protection strategy to successfully prepare phase‐pure iron powder from Fe‐based metal‐organic frameworks. Notably, the resulting iron powder exhibits good antioxidant and acid‐resistant properties. As an NRR electrocatalyst, it delivers an ammonia yield rate of 120.05 µg h −1 mg cat. −1 and an FE of 43.44%–a 20‐fold enhancement over commercial iron powder. The enhanced NRR activity is primarily attributed to the improved N 2 ‐enrichment, facilitated N 2 ‐activation, and effective suppression of the competitive hydrogen evolution. With only 3.83 wt% cobalt (Co) doping, the Co‐doped iron powder achieves the substantially enhanced NH 3 yield rate of 200.50 µg h −1 mg cat. −1 with an FE of 56.34% at a high current density of 7 mA cm −2 . The combined experimental and theoretical analyses reveal that Fe vacancies are key to the adsorption and activation of N 2 . This work provides a powerful guidance for developing more bulk transition metals to achieve green ammonia synthesis at a more industrial level.