尿素是一種多功能性的有機化合物，作為農作物肥料的主要原料之一，其經濟價值不言而喻。然傳統工業製備尿素需要在高溫高壓的條件下進行，其所耗費之能源較高，改良尿素之製備方法是現代科學的一大課題。電化學金屬非勻相催化二氧化碳與硝酸根/亞硝酸根共還原之反應能夠在常溫常壓的條件下生成尿素，此反應在銅表面上有良好的反應性，不過其反應途徑尚未確定，因此我們的團隊先前在銅(111)表面上進行一系列之理論計算研究，希望藉由確認反應途徑，為優化實驗條件提供建議。此外根據他人的研究指出，銅(100)表面上的雙橋位點(double-bridge site)對鍵結生成或斷裂的反應性較高，我們認為它能提高碳氮鍵生成反應性的潛力。本研究在銅(100)表面上、水相且反應之pH值為7的條件下，模擬CO2與NO3-/NO2-共還原生成尿素的反應。與先前在銅(111)表面上的研究不同，第一個碳氮鍵的生成有兩種可行的反應途徑，在這之中，雙橋位點確實可以促進表面反應的反應性，並且藉由活化能拆解分析法的結果，我們發現發生於雙橋位點的第一個碳氮鍵生成反應有較低的相互作用能，以及較低的*CO形變能。結合計算結果與他人的實驗證據，我們發現第二個碳氮鍵生成的反應途徑與推測不同，是由*NCO與溶液中的氨(NH3)反應產生的，在外加電壓為-1.0 VSHE時，其反應活化能為0.40 eV，後續經過熱力學上可行之一個氫離子解離以及兩次氫化後，即可得到尿素。此研究對於在銅(100)表面上進行CO2與NO3-/NO2-共還原生成尿素的反應，提供了一個完整的反應路徑推測，並且推論若提高系統中氨的濃度，可能會提高第二個碳氮鍵生成的反應性，進而提高尿素的產率。

Urea, a versatile organic compound widely used as a primary ingredient in agricultural fertilizers, holds significant economic value. Traditional industrial methods for urea synthesis involve high-temperature and high-pressure conditions, leading to substantial energy consumption. Developing alternative and energy-efficient approaches for urea production is a pressing challenge in modern science. Electrochemical metal heterogeneous catalysis has shown promise in the co-reduction of carbon dioxide (CO2) and nitrate/nitrite ions (NO3-/NO2-), which can lead to urea formation under ambient conditions. Copper surfaces have demonstrated remarkable reactivity in this reaction; however, the precise reaction pathway remains unclear. In this study, we conducted a series of theoretical calculations on copper (100) surfaces to shed light on the reaction mechanism. The investigation revealed the crucial role of double-bridge sites on copper (100) surfaces, which enhance the reactivity for the formation of the first carbon-nitrogen bond. Additionally, by integrating computational insights with experimental findings, we discovered that the formation of the second carbon-nitrogen bond involves the reaction between *NCO and ammonia (NH3) in the solution. Under an applied voltage of -1.0 VSHE, the reaction barrier is equal to 0.40 eV. The proposed reaction pathway, along with suggested optimizations of experimental conditions, contributes to the advancement of efficient urea synthesis through the co-reduction of CO2 and NO3-/NO2- on copper (100) surface.

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