The nitrogen cycle needed for scaled agriculture relies on energy- and carbon-intensive processes and generates nitrate-containing wastewater. Here we focus on an alternative approach—the electrified co-electrolysis of nitrate and CO₂ to synthesize urea. When this is applied to industrial wastewater or agricultural runoff, the approach has the potential to enable low-carbon-intensity urea production while simultaneously providing wastewater denitrification. We report a strategy that increases selectivity to urea using a hybrid catalyst: two classes of site independently stabilize the key intermediates needed in urea formation, *CO₂NO₂ and *COOHNH₂, via a relay catalysis mechanism. A Faradaic efficiency of 75% at wastewater-level nitrate concentrations (1,000 ppm NO₃⁻ [N]) is achieved on Zn/Cu catalysts. The resultant catalysts show a urea production rate of 16 µmol h⁻¹ cm⁻². Life-cycle assessment indicates greenhouse gas emissions of 0.28 kg CO₂e per kg urea for the electrochemical route, compared to 1.8 kg CO₂e kg⁻¹ for the present-day route.

规模化农业所需的氮循环依赖于能源和碳密集型过程，并产生含硝酸盐的废水。_{在这里，我们关注另一种方法——硝酸盐和CO 2}的电共电解来合成尿素。当将其应用于工业废水或农业径流时，该方法有可能实现低碳强度尿素生产，同时提供废水脱氮。我们报告了一种使用混合催化剂提高尿素选择性的策略：两类位点独立稳定尿素形成所需的关键中间体，*CO ₂ NO ₂和*COOHNH ₂，通过中继催化机制。Zn/Cu 催化剂在废水水平硝酸盐浓度（1,000 ppm NO ₃ ^- [N]）下实现了 75% 的法拉第效率。^{所得催化剂显示出16μmol h -1}  cm ^-2的尿素生产率。生命周期评估表明电化学路线每公斤尿素的温室气体排放量为0.28 kg CO ₂ e kg -1 ，而当前路线的温室气体排放量为1.8 kg CO ₂ e kg ^{-1 。}