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

Li, Shurong; Su, Yiwen; Wan, Hao; Jiang, Zhehang; Niu, Tianhao; Zhang, Yong; Huang, Wei; Zeng, Libin et al. · Nano Lett · 2025

basic_science · Level V

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Abstract

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<sup>-1</sup>·cm<sup>-2</sup> 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<sup>-1</sup>·cm<sup>-2</sup> at 1 A·cm<sup>-2</sup>. This work pioneers new pathways for developing efficient catalysts toward the industrial application of eNRA.