Electrocatalytically Active Fe‐(O‐C2)4 Single‐Atom Sites for Efficient Reduction of Nitrogen to Ammonia

Abstract Single‐atom catalysts have demonstrated their superiority over other types of catalysts for various reactions. However, the reported nitrogen reduction reaction single‐atom electrocatalysts for the nitrogen reduction reaction exclusively utilize metal–nitrogen or metal–carbon coordination configurations as catalytic active sites. Here, we report a Fe single‐atom electrocatalyst supported on low‐cost, nitrogen‐free lignocellulose‐derived carbon. The extended X‐ray absorption fine structure spectra confirm that Fe atoms are anchored to the support via the Fe‐(O‐C2)4 coordination configuration. Density functional theory calculations identify Fe‐(O‐C2)4 as the active site for the nitrogen reduction reaction. An electrode consisting of the electrocatalyst loaded on carbon cloth can afford a NH3 yield rate and faradaic efficiency of 32.1 μg h−1 mgcat.−1 (5350 μg h−1 mgFe−1) and 29.3 %, respectively. An exceptional NH3 yield rate of 307.7 μg h−1 mgcat.−1 (51 283 μg h−1 mgFe−1) with a near record faradaic efficiency of 51.0 % can be achieved with the electrocatalyst immobilized on a glassy carbon electrode.