Achieving Near 100% Faradaic Efficiency of Electrocatalytic Nitrate Reduction to Ammonia on Symmetry-Broken Medium-Entropy-Alloy Metallene
Yuanbo Zhou, Lifang Zhang, Mengfan Wang, Zebin Zhu, Najun Li, Tao Qian, Chenglin Yan, Jianmei Lu
Abstract
Electrochemical nitrate reduction (NO 3 RR) 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% NH 3 Faradaic efficiency in both neutral and alkaline electrolytes, along with a record-high NH 3 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 NO 2 – are also hindered. We believe that our strategy proposed in this work will shed light on the design of efficient NO 3 RR catalysts to a more practical level.