This study investigates the electrochemical synthesis of urea using nitrite and carbon dioxide on copper (Cu) surfaces, focusing on the role of the working electrode potential and the electric double-layer capacitance. The research employs a constant-potential method combined with an implicit solvent model to explore the reaction mechanisms and activities. Key findings include: 1. **Working Electrode Potential**: The previously overlooked potential effect is found to be crucial in determining the reaction mechanism and activity. The potential influences the formation of key intermediates, such as *CO-NH* and *NH-CO-NH*. 2. **Microkinetic Model**: Analysis of turnover frequencies under various potentials, pressures, and temperatures reveals that activity increases with temperature, and Cu(100) shows the highest efficiency for urea synthesis among the studied Cu surfaces. 3. **Electric Double-Layer Capacitance**: The capacitance of the electric double-layer plays a significant role in the kinetic barrier for the rate-determining step. Higher capacitance values are associated with better performance. 4. **Strategies for Enhanced Efficiency**: Based on these findings, two strategies are proposed to improve urea synthesis efficiency: increasing the (100) surface ratio and elevating the reaction temperature. The study provides a comprehensive understanding of the electrochemical urea synthesis process, highlighting the importance of potential and electric double-layer effects in promoting efficient urea production.This study investigates the electrochemical synthesis of urea using nitrite and carbon dioxide on copper (Cu) surfaces, focusing on the role of the working electrode potential and the electric double-layer capacitance. The research employs a constant-potential method combined with an implicit solvent model to explore the reaction mechanisms and activities. Key findings include: 1. **Working Electrode Potential**: The previously overlooked potential effect is found to be crucial in determining the reaction mechanism and activity. The potential influences the formation of key intermediates, such as *CO-NH* and *NH-CO-NH*. 2. **Microkinetic Model**: Analysis of turnover frequencies under various potentials, pressures, and temperatures reveals that activity increases with temperature, and Cu(100) shows the highest efficiency for urea synthesis among the studied Cu surfaces. 3. **Electric Double-Layer Capacitance**: The capacitance of the electric double-layer plays a significant role in the kinetic barrier for the rate-determining step. Higher capacitance values are associated with better performance. 4. **Strategies for Enhanced Efficiency**: Based on these findings, two strategies are proposed to improve urea synthesis efficiency: increasing the (100) surface ratio and elevating the reaction temperature. The study provides a comprehensive understanding of the electrochemical urea synthesis process, highlighting the importance of potential and electric double-layer effects in promoting efficient urea production.