A Reaction-Diffusion-Coupled Strategy for Ampere-Level Electrocatalytic Nitrate Reduction to Ammonia

Ampere-level electrocatalytic nitrate reduction to ammonia (eNRA) offers a carbon-neutral alternative to the Haber-Bosch process. However, its energy efficiency is critically hampered by the inherent conflict between the reaction and diffusion. Herein, we propose a reaction-diffusion-coupled strategy implemented on a well-tailored CuCoNiRuPt high-entropy alloy aerogel (HEAA) to simultaneously realize energy barrier homogenization and accelerate mass transport, endowing ampere-level eNRA with a high energy efficiency. The resultant HEAA delivers an ammonia yield rate of 3.4 ± 0.3 mmol·h-1·cm-2 and a Faradaic efficiency of 98 ± 2% at a record-low overpotential of -0.05 V versus a reversible hydrogen electrode, enabling an energy efficiency of 41.5 ± 0.8% and a durable operation at industrial current density. Pragmatic deployment is further envisaged in a membrane electrode assembly electrolyzer to achieve practical-scale ammonia production with a yield rate of 4.3 ± 0.1 mmol·h-1·cm-2 at 1 A·cm-2. This work pioneers new pathways for developing efficient catalysts toward the industrial application of eNRA.