Electrocatalytic nitrate reduction to ammonia holds great promise for developing green technologies for electrochemical ammonia energy conversion and storage. Considering that real nitrate resources often exhibit low concentrations, it is challenging to achieve high activity in low-concentration nitrate solutions due to the competing reaction of the hydrogen evolution reaction, let alone considering the catalyst lifetime. Herein, we present a high nitrate reduction performance electrocatalyst based on a Co nanosheet structure with a gradient dispersion of Ru, which yields a high NH₃ Faraday efficiency of over 93% at an industrially relevant NH₃ current density of 1.0 A/cm² in 2000 ppm NO₃^- electrolyte, while maintaining good stability for 720 h under −300 mA/cm². The electrocatalyst maintains high activity even in 62 ppm NO₃^- electrolyte. Electrochemical studies, density functional theory, electrochemical in situ Raman, and Fourier-transformed infrared spectroscopy confirm that the gradient concentration design of the catalyst reduces the reaction energy barrier to improve its activity and suppresses the catalyst evolution caused by the expansion of the Co lattice to enhance its stability. The gradient-driven design in this work provides a direction for improving the performance of electrocatalytic nitrate reduction to ammonia.

电催化硝酸盐还原为氨对于开发电化学氨能量转换和存储的绿色技术具有广阔的前景。考虑到真正的硝酸盐资源通常表现出低浓度，由于析氢反应的竞争反应，在低浓度硝酸盐溶液中实现高活性具有挑战性，更不用说考虑催化剂寿命了。在此，我们提出了一种基于具有 Ru 梯度分散的 Co 纳米片结构的高硝酸盐还原性能电催化剂，在工业相关的 NH ₃ 法拉第效率。 /b1> 在 2000 ppm NO ₃ ^- 电解质中电流密度为 1.0 A/cm ² ，同时在 -300 mA/cm 下保持 720 小时良好的稳定性 ² 。即使在 62 ppm NO ₃ ^- 电解质中，电催化剂仍保持高活性。电化学研究、密度泛函理论、电化学原位拉曼和傅里叶变换红外光谱证实，催化剂的梯度浓度设计降低了反应能垒，提高了其活性，并抑制了Co晶格膨胀引起的催化剂演化，从而提高了催化剂的活性。增强其稳定性。这项工作中的梯度驱动设计为提高电催化硝酸盐还原氨的性能提供了方向。