Boosting Nitrogen Reduction Activity by Defect Engineering in 2D Iron Monochalcogenides FeX (X=S, Se)

Large‐scale ammonia synthesis under ambient environment is a highly demanding technology which is promising to replace the energy‐consuming Haber–Bosch process. Motivated by the crucial iron–sulfur interaction in nitrogenase, the performance of 2D iron monochalcogenides (FeX, X=S, or Se) toward electrochemical nitrogen reduction reaction (e‐N2RR) by means of density functional theory calculations is explored. It is confirmed that pristine 2D FeX is inert for even N 2 adsorption while defective 2D FeX with single‐anion‐point vacancy ( V X ) demonstrates considerable activity for NRR. The enhancement is attributed to the interaction between defect‐induced states and p ‐orbitals of nitrogen, which greatly alters the adsorption behavior of N 2 molecule. Meanwhile, the relation between the N 2 adsorption free energy and theoretical limiting potential ( U L ) agrees well with the previous report. Moreover, the 2D nature of FeX provides flexible adsorption sites for both N 2 and proton, alleviating the competition between e‐N2RR and hydrogen evolution reaction. As the existence of V S and V Se in tetragonal iron monochalcogenides has been validified by experiments, a facile strategy for designing practical and economical NRR electrocatalysts is provided and might be extended to the study of other species of defects in catalysis.