Electrochemical nitrate reduction (NO₃RR) offers an ecofriendly way for ammonia production. However, improving the sluggish kinetics of such a multistep reaction still remains challenging. Herein, an asymmetry strategy is proposed to adjust the charge distribution of the active centers on metallene by presenting novel symmetry-broken medium-entropy-alloy (MEA) metallene via heteroatom alloying. Benefiting from the maximized exposure of the well-regulated active sites, proof-of-concept PdCuCo MEA metallene delivers near 100% NH₃ Faradaic efficiency in both neutral and alkaline electrolytes, along with a record-high NH₃ yield rate over 532.5 mg h^–1 mg_cat^–1. Moreover, it enables 99.7% conversion of nitrate from an industrial wastewater level of 6200 ppm to a drinkable water level. Detailed studies further revealed that charge redistribution is induced by the elemental electronegativity difference on symmetry-broken MEA metallene, which will weaken the N–O bond of *NO, thus reducing the energy barrier of the rate-determining step. Meanwhile, the competitive HER and the formation of NO₂^– are also hindered. We believe that our strategy proposed in this work will shed light on the design of efficient NO₃RR catalysts to a more practical level.

中文翻译：

---

在对称破缺的中熵合金金属上实现电催化硝酸盐还原成氨的近 100% 法拉第效率

电化学硝酸盐还原（NO ₃ RR）为氨生产提供了一种生态友好的方式。然而，改善这种多步反应的缓慢动力学仍然具有挑战性。在此，提出了一种不对称策略，通过杂原子合金化提出新型对称破缺的中熵合金（MEA）金属烯来调整金属烯上活性中心的电荷分布。受益于良好调节的活性位点的最大化暴露，概念验证的 PdCuCo MEA 金属烯在中性和碱性电解质中提供接近 100% 的 NH ₃法拉第效率，以及超过 532.5 mg h 的创纪录高 NH ₃产率^–1毫克_猫^–1 .此外，它能够将 99.7% 的硝酸盐从 6200 ppm 的工业废水转化为饮用水水平。详细的研究进一步表明，电荷重新分布是由对称破缺的MEA金属烯上的元素电负性差异引起的，这会削弱*NO的N-O键，从而降低速率决定步骤的能垒。同时，竞争性HER和NO ₂ ^–的形成也受到阻碍。我们相信，我们在这项工作中提出的策略将为高效NO ₃ RR催化剂的设计提供更实用的水平。