Single‐Atom Fe Catalysts with Improved Metal Loading for Efficient Ammonia Synthesis under Mild Conditions

Ammonia synthesis is a cornerstone in the chemical industry. Given the traditional Haber‐Bosch (H‐B) process requires very high temperature and pressure, it is imperative to develop catalysts capable of facilitating ammonia synthesis under mild conditions. In this work, a post‐metal replacement strategy is developed to improve the Fe loading in single‐atom Fe‐implanted N‐doped carbon catalysts. Starting from the Zn‐Fe‐N‐C material with single‐atom Zn and Fe sites coexisting in N‐doped porous carbon pyrolyzed from porphyrinic metal‐organic frameworks (MOFs), the replacement of single‐atom Zn with Fe sites is performed, which significantly increases the Fe loading from 1.33 wt% to 2.39 wt%. This effectively suppresses the migration and agglomeration of Fe, yielding Fe‐N‐C with high metal loading (FeHL‐N‐C). Notably, the FeHL‐N‐C catalyst exhibits a catalytic rate of 558 μmol·gcat‐1·h‐1 at 300 °C for ammonia synthesis at atmospheric pressure, far surpassing the performance of the traditional dominant fused iron and even Ru‐based precious metal catalysts.