Hierarchical superwetting electrodes with tunable triphase interface for efficient ammonia synthesis

Electrocatalytic nitrogen reduction reaction (NRR) offers a promising alternative to the Haber-Bosch process. However, its efficiency is critically limited by poor gas diffusion and competing adsorption of H₂O/H^∗ intermediates. Herein, we develop a universal hierarchical micro-/nano-structuring strategy to overcome these challenges by constructing superwetting micro-cavity electrodes with a tunable triphase interface. It enhances multidimensional gas diffusion to enrich local N₂ while regulating interfacial coverage of H₂O/H^∗ intermediates, thereby shifting the reaction pathway toward NRR. Consequently, compared with conventional electrodes, the Faradaic efficiency increases by over an order of magnitude—from 2.47% to 29.37% at 0 V vs. RHE. Mechanistic investigations reveal that micro-cavity electrodes with a Wenzel-Cassie coexistence state modulate N₂/H₂O transport, promoting N₂ diffusion and suppressing hydrogen evolution to establish an optimized localized triphase microenvironment for NRR. This work integrates interfacial engineering with hierarchical micro-/nano-engineering, offering a sustainable approach for addressing critical challenges in renewable nitrogen fixation.