Strengthened CO₂-to-CO Electroreduction from Low-Concentration CO₂Streams via the Phosphorus Heteroatoms-Regulated Electronic Structure of a Single Atomic FeN₄Catalyst

Single atomic Fe catalysts have demonstrated excellent activity for pure CO₂electroreduction (CO₂RR). However, designing a highly active catalyst for efficient CO₂RR from streams with diluted CO₂concentration remains a significant challenge. Herein, P atoms were introduced into the second coordination shell of FeN₄(FeN₄P), forming Fe–N–P bonds to facilitate the CO₂-to-CO conversion in an aqueous solution. The incorporation of P atoms enhanced both the activity and selectivity toward CO, reaching a maximum CO Faradaic efficiency (FE_CO) of 96.2 ± 0.5% at a current density exceeding −200 mA cm^–2in 0.5 M KHCO₃. Moreover, the superior activity was further demonstrated by the 80.5 ± 2.3 and 61.5 ± 1.3% FE_COat optimized conditions from streams containing only 15 and 5% CO₂, respectively. In situ characterizations reveal that the asymmetric FeN₄P structure enhanced the kinetics of adsorbed CO₂reduction. Density functional theory calculation revealed that the electron-enriched FeN₄center, modulated by the adjacent P atom, facilitated CO₂adsorption and activation and lowered the energy barrier for *COOH formation, thereby promoting CO₂-to-CO conversion.