Breaking the Performance Limit of Pure Metals for N ₂ Electroreduction

Abstract The electrocatalytic nitrogen reduction reaction (NRR) offers a sustainable pathway for ambient‐condition ammonia synthesis, yet its efficiency is fundamentally limited by the low N 2 concentration in aqueous systems and the competing strong adsorption of H 2 O/H intermediates on conventional bulk metal catalysts. Herein, we propose a universal micro/nanoengineering strategy to address these challenges by constructing three‐phase‐interface‐optimized hollow fiber (HF) electrodes. This design simultaneously enhances local N 2 enrichment and modulates the surface coverage of critical intermediates (*N 2 versus *H), thereby shifting the reaction equilibrium toward NRR. As a proof of concept, Fe‐based HF electrodes achieve a remarkable NH 3 yield rate of 27.1 µg h −1 cm −2 and a Faradaic efficiency (FE) of 3.5% under ambient conditions—values dramatically enhanced by ∼60‐fold and ∼35‐fold, respectively, compared to planar Fe electrodes. Mechanistic studies reveal that the hierarchical porous architecture of HF electrodes promotes N 2 diffusion and alters the adsorption hierarchy of intermediates, effectively suppressing hydrogen evolution while activating N≡N bond cleavage. Crucially, this strategy demonstrates broad applicability, as evidenced by significantly improved NRR performance across diverse metals (e.g., Cu, Ni), highlighting its potential as a general platform for advancing sustainable ammonia electrosynthesis.