Ampere-Level Membrane-Free Bipolar Ammonia Electrosynthesis with Faradaic Efficiency Exceeding 100% on a...

Awaking the force of materials for specific efficacy by precise electronic modulation remains a fundamental challenge in catalysis. Herein, we transform ordinary NiFe-layered double hydroxide (NiFe-LDH) into a high-performance NO₃ ^--to-NH₃ electrocatalyst via cathodic electrochemical restructuring, which effectively induces oxygen vacancy (O_v) clusters preferentially localized around low-valence Ni sites. The resultant restructured NiFe-LDH (NiFe-LDH-R) demonstrates excellent concentration-universal NH₃ electrosynthesis activity in 1 M KOH, notably sustaining high Faradaic efficiencies (FEs, 88.5%-95%) across a broad potential range and attaining an ampere-level current density (-1.46 A cm^-2) together with a remarkable yield rate of 104.1 mg_NH3 h^-1 cm^-2. In situ spectroscopic analyses reveal boosted hydrogenation kinetics and a thermodynamically favorable NOH pathway for NiFe-LDH-R, which is further decoded by theoretical calculations indicating that synergized O_v/Fe and low-valence Ni sites, respectively enhance NO₃ ^- adsorption and directional active hydrogen (*H) supply, thus streamlining overall energy barriers. Moreover, a new-style membrane-free bipolar electrosynthesis system is established, which enables unprecedent NH₃ FEs exceeding 100% and scalable NH₃ valorization into 4.1 g of methenamine. This study rekindles power of electrochemical restructuring in catalyst advance and pioneers a new paradigm for energy-efficient electrochemical NH₃ production and fixation.