Periodic Defect Engineering of Iron–Nitrogen–Carbon Catalysts for Nitrate Electroreduction to Ammonia

Iron–nitrogen–carbon single atom catalyst (SAC) is regarded as one of the promising electrocatalysts for NO₃⁻ reduction reaction (NO₃RR) to NH₃ due to its high activity and selectivity. However, synergistic effects of topological defects and FeN₄ active moiety in Fe–N–C SAC have rarely been investigated. By performing density functional theory (DFT) calculations, 13 defective graphene FeN₄ with 585, 484, and 5775 topological line defects are constructed, yielding 585-68-FeN₄ with optimal NO₃RR catalytic activity, high selectivity, as well as robust anti-dissolution stability. The high NO₃RR activity on 585-68-FeN₄ is well explained by the high valence state of Fe center as well as asymmetric charge distribution on FeN₄ moiety influenced by 5- and 8-member rings. This DFT work provides theoretical guidance for engineering NO₃RR performance of iron–nitrogen–carbon catalysts by modulating periodic topological defects.