Intensified Electron Transfer via a Nitrogen-Enriched Surface Boosts Fischer–Tropsch Activity of Fe ₃ C@C Catalysts

The surface nitrogen concentration governs interfacial electron transfer in nitrogen-doped carbon-wrapped Fe 3 C catalysts for Fischer–Tropsch synthesis (FTS). By controlling surface nitrogen density at fixed total nitrogen content, we demonstrate the nitrogen-sufficient surface in Fe 3 C@C (Fe@NC-S) intensifies interfacial electron flux via enhanced Fe–N coordination. This yields a 4-fold increase in CO conversion rate (109.4 vs 27.4 μmol CO g Fe –1 s –1 ) relative to nitrogen-deficient Fe@NC, while preserving identical C 5+ selectivity (42.1%). Spectroscopic and computational studies reveal the nitrogen-enriched surface reduces Fe 3 C → C electron leakage (+1.619 e vs +1.906 e) and boosts Fe 3 C → CO* back-donation (+0.264 e vs +0.243 e), concentrating electron density at Fe 3 C active sites to drive CO activation without altering chain-growth kinetics. This work establishes surface nitrogen engineering as a viable strategy for next-generation FTS catalysts with activity–selectivity synergy.