Breaking the Performance Limit of Pure Metals for N₂ Electroreduction

The electrocatalytic nitrogen reduction reaction (NRR) offers a sustainable pathway for ambient-condition ammonia synthesis, yet its efficiency is fundamentally limited by the low N₂ concentration in aqueous systems and the competing strong adsorption of H₂O/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 N₂ enrichment and modulates the surface coverage of critical intermediates (*N₂ versus *H), thereby shifting the reaction equilibrium toward NRR. As a proof of concept, Fe-based HF electrodes achieve a remarkable NH₃ 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 N₂ 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.