Erbium‐Induced Interfacial Adsorption Regulation on Copper Enables Efficient Nitrite‐CO 2 Coupling for Sustainable Electrochemical Urea Synthesis

Industrial wastewater rich in nitrite and anthropogenic CO 2 emissions are typically treated as separate waste streams, requiring energy‐intensive management. Here we report an electrochemical strategy that couples nitrite and carbon dioxide to synthesize urea, enabling simultaneous pollution mitigation and resource recovery. An erbium‐doped copper nanocatalyst is developed to promote selective C─N coupling, delivering a urea yield of 510.29 mg h −1 g cat −1 with a Faradaic efficiency of 34.04%. At the same time, higher removal rate of nitrite can be achieved and sustained performance over repeated cycles. The mechanism reveals that Er doping can adjust the adsorption behavior of intermediate substances at Cu interface, make the upward shift of the d‐band center of Cu, enhance the adsorption of *CO 2 and *NH 2 at the active site of Cu, reduce the energy barrier formed of the C─N coupling step *CO 2 NH 2 , and reduce the energy barrier of thermodynamically limiting step *COOHNH 2 formation, and promote the synthesis of urea. Beyond catalytic performance, the resulting electrolyte can be directly reused for irrigation, where it enhances early‐stage growth of crops, demonstrating a closed‐loop integration of carbon and nitrogen utilization. This work establishes a proof‐of‐concept for transforming coupled waste streams into value‐added chemicals while linking electrochemical conversion with agricultural application. The approach provides a scalable pathway toward circular carbon‐nitrogen management and sustainable environmental remediation.