Identification of FeN4 as an Efficient Active Site for Electrochemical N2 Reduction

Electrocatalytic N2 reduction to NH3 is an attractive method for artificial N2 fixation at ambient conditions. Herein, we demonstrate that Fe-NC materials could be efficient for electrochemical N2 reduction reaction (NRR) using iron phthalocyanine (FePc) with a well-defined FeN4 configuration as a model catalyst. By uniformly loading FePc molecules on porous carbon, it exhibits a high electrocatalytic activity for NRR with a NH3 yield rate of 137.95 μg h–1 mg–1 FePc at a low potential of −0.3 V (vs RHE). Importantly, by making comparisons with phthalocyanine without the Fe center and performing control and poisoning experiments together with theoretical calculations, we identify the Fe center in FeN4 as the most active site for NRR among five possible sites in FePc and discover that the preferred route is the alternating pathway of N2 on Fe. These results open up opportunities for further exploring metal-nitrogen-carbon materials for highly efficient electrochemical N2 fixation and NH3 production.