The importance of C7 sites and surface roughness in the ammonia synthesis reaction over iron

Ammonia is a critical feedstock for modern industry and agriculture, which is also a promising carbon-free energy carrier. Electrochemical nitrogen reduction reaction (ENRR) is a sustainable and efficient approach to synthesize ammonia under ambient reaction conditions. ENRR relies on the development of highly efficient electrocatalysts. So far various strategies have been applied to enhance the performance of catalysts including tuning the electronic structure, binding strength, coordination configuration as well as the introduction of multiple active sites and defects. In this review, the recent progress of Fe-based electrocatalysts and their coordination effect, synergistic effect and defect effect for nitrogen reduction reaction have been summarized. Our critical review focuses on the discussion of theoretical advancement, the performance origin of ENRR activity and selectivity of Fe-based electrocatalysts.