Tailored Interfacial Water Kinetics Enhancing N ₂ Electroreduction to Ammonia over Alkanethiol-Functionalized Iron Hollow-Fiber Penetration Electrodes

The electrocatalytic nitrogen reduction reaction (NRR), offering an attractive route to ammonia (NH3) from dinitrogen (N2) and water, has attracted substantial interest. However, conventional hydrophobic modification strategies face comprehensive challenges: effectively inhibiting the competing hydrogen evolution reaction (HER) inevitably impedes the critical proton-coupled electron transfer (PCET) steps essential for efficient NRR. Herein, we present a high-performance electrocatalyst based on alkanethiol-modified iron hollow fibers (Fe HF-Cx, x = 6, 12, and 18). Significantly, the optimized Fe HF-C12 achieves water management at the interface, suppressing HER without hindering the dynamic water activity essential for proton supply during NRR. Compared to the unmodified Fe HF (3.5%, 27.1 μg h–1 cm–2), this distinctive interfacial design achieves a significantly improved Faradaic efficiency of 18.8% and a higher NH3 yield rate of 40.0 μg h–1 cm–2. Multitechnique characterizations and simulations unveil the triple synergistic function of the alkanethiol layer: (i) N2 enrichment at the electrode–electrolyte interface, (ii) selective suppression of HER without impeding dynamic water activity for PCET, and (iii) corrosion inhibition via robust thiolate-Fe bonding.