Abstract
Iron-intercalated Mo(2)C MXene (Fe/Mo(2)C) is presented as a robust, earth-abundant electrocatalyst for ambient ammonia synthesis. An in situ HF protocol converts Mo(2)Ga(2)C MAX into few-layer Mo(2)C terminated with =O/-F groups; subsequent wet impregnation followed by mild reduction deposits 7 wt % Fe(0) as an epitaxial coating that lines the internal van der Waals galleries and simultaneously blankets the external basal planes of the Mo(2)C MXene. Aberration-corrected STEM, FFT/inverse-FFT analysis, and STEM-EDX depth profiling verify lamellar Fe domains that connect neighboring Mo(2)C sheets while preserving crystallinity. This hybrid architecture halves the charge-transfer resistance (EIS) and provides a high density of Fe sites that preferentially adsorb N(2) over protons. In neutral 0.1 M Na(2)SO(4), the optimized material achieves a Faradaic efficiency of 28.8% and an NH(3) yield of 19.1 μmol h(-1) mg(Fe) (-1) at 0.25 V vs RHE, matching or surpassing noble-metal benchmarks under ambient conditions. Operando ATR-SEIRAS detects N-N and -NH (x) vibrations consistent with an associative pathway, and (15)N(2) labeling confirms the nitrogen source. The catalyst maintains stable performance for 10 h with no detectable Fe leaching. Thus, the combination of the activity of Fe overlayers with the conductive, mechanically resilient Mo(2)C framework renders a material with remarkable electrocatalytic activity for green-ammonia production.