隨著工業發展的版圖越來越大，人面漸漸意識到環境永續的重要性，減少污染排放或是資源的再利用都是現在科學家研究的重點目標，如今已有許多科學家使用電化學催化的方式進行合成反應，電能屬於可再生的能源，而參與反應的原料也可以來自各種工業排放的污染物，例如CO2。以CO2作為起始物進行電化學還原反應，其還原過程中所產生的中間產物CO可以再拿來與其他物質進行更多反應，生成各式各樣具有經濟價值的產物，已有研究團隊發現，在Cu100的表面上將CO與NH3於鹼性環境進行共電催化，最終可以得到乙醯胺的產物。然而上述實驗的反應機制尚未被完全的研究透徹，所以本次研究將以量子化學為基礎，利用理論計算的方式，挑選在CO與NH3共還原的反應中，最可能產生乙醯胺之反應路徑，藉由在Constant-U(固定電壓)的計算系統下，模擬電化學的環境，進行動力學以及熱力學的篩選，從CO以及其還原反應中衍生之C1(單碳)、C2(雙碳)中間物之中，挑選出最具潛力的反應物，並模擬其與NH3反應後續生成醯胺類產物之可能反應路徑。最終我們發現了三個可能與NH3反應生成醯胺類產物的C2中間物–*HCCO, *H2CCO, *OCHCO，同時也發現C1中間物與NH3的反應性不佳，而C1中間物彼此之間進行C–C偶合的反應卻較為可行，利用這個發現可以解釋為什麼參考文獻所提供的實驗結果中，只有看到乙醯胺(CH3CONH2)的生成，而非甲醯胺(HCONH2)。

As the industrial continues to expand, people are gradually realizing the importance of environmental sustainability. Whether reducing pollution emissions or recycling resources are the main objectives of scientific research today. Many scientists are now using electrochemical catalysis involved in the reactants which can come from various industrial pollutants, such as CO2 . One research group have discovered that by conducting electrocatalysis of CO(reduced from CO2) and NH3 on the surface of Cu100 in an alkaline environment, acetamide can be obtained as the final product.
However, the reaction mechanism of the aforementioned experiment has not been studied completely yet. Therefore, this study is using theoretical calculations to find the most probable reaction pathways for the co-electrolysis of CO and NH3, to simulate the electrochemical environment, we using the constant-U system. Kinetics and thermodynamics are screened to identify the most promising reactants among numerous CO and its derived C1 and C2 intermediates. Subsequently, the possible reaction pathways leading to acetamide formation are estimated.
Ultimately, three C2 intermediates that could potentially react with NH3 to produce acetamide were discovered. It was also found that the reactivity of C1 intermediates with NH3 is poor, but instead, the coupling reactions of C1 intermediates with each other are more feasible. This explains why main C–N product observed in the experiment is acetamide rather than formamide.

1. Constable, D. J. C.; Dunn, P. J.; Hayler, J. D.; Humphrey, G. R.; Leazer, J. J. L.; Linderman, R. J.; Lorenz, K.; Manley, J.; Pearlman, B. A.; Wells, A.; Zaks, A.; Zhang, T. Y., Key green chemistry research areas—a perspective from pharmaceutical manufacturers. Green Chem. 2007, 9 (5), 411-420.
2. Ojeda-Porras, A.; Gamba-Sanchez, D., Recent Developments in Amide Synthesis Using Nonactivated Starting Materials. J Org Chem 2016, 81 (23), 11548-11555.
3. Pattabiraman, V. R.; Bode, J. W., Rethinking amide bond synthesis. Nature 2011, 480 (7378), 471-9.
4. Dunetz, J. R.; Magano, J.; Weisenburger, G. A., Large-Scale Applications of Amide Coupling Reagents for the Synthesis of Pharmaceuticals. Organic Process Research & Development 2016, 20 (2), 140-177.
5. Nitopi, S.; Bertheussen, E.; Scott, S. B.; Liu, X.; Engstfeld, A. K.; Horch, S.; Seger, B.; Stephens, I. E. L.; Chan, K.; Hahn, C.; Norskov, J. K.; Jaramillo, T. F.; Chorkendorff, I., Progress and Perspectives of Electrochemical CO(2) Reduction on Copper in Aqueous Electrolyte. Chem Rev 2019, 119 (12), 7610-7672.
6. Jouny, M.; Lv, J. J.; Cheng, T.; Ko, B. H.; Zhu, J. J.; Goddard, W. A., 3rd; Jiao, F., Formation of carbon-nitrogen bonds in carbon monoxide electrolysis. Nat Chem 2019, 11 (9), 846-851.
7. Perdew, J. P. B., K.; Ernzerhof, M, Generalized Gradient Approximation Made Simple. Phys. Rev. Lett 1996, 77, 3865– 3868.
8. Grimme, S.; Antony, J.; Ehrlich, S.; Krieg, H., A consistent and accurate ab initio parametrization of density functional dispersion correction (DFT-D) for the 94 elements H-Pu. J Chem Phys 2010, 132 (15), 154104.
9. Montoya, J. H.; Shi, C.; Chan, K.; Norskov, J. K., Theoretical Insights into a CO Dimerization Mechanism in CO2 Electroreduction. J Phys Chem Lett 2015, 6 (11), 2032-7.
10. Huang, Y.; Handoko, A. D.; Hirunsit, P.; Yeo, B. S., Electrochemical Reduction of CO2 Using Copper Single-Crystal Surfaces: Effects of CO* Coverage on the Selective Formation of Ethylene. ACS Catalysis 2017, 7 (3), 1749-1756.
11. Henkelman, G.; Jónsson, H., A dimer method for finding saddle points on high dimensional potential surfaces using only first derivatives. The Journal of Chemical Physics 1999, 111 (15), 7010-7022.
12. Goodpaster, J. D.; Bell, A. T.; Head-Gordon, M., Identification of Possible Pathways for C-C Bond Formation during Electrochemical Reduction of CO2: New Theoretical Insights from an Improved Electrochemical Model. J Phys Chem Lett 2016, 7 (8), 1471-7.
13. Xiao, H.; Cheng, T.; Goddard, W. A., 3rd; Sundararaman, R., Mechanistic Explanation of the pH Dependence and Onset Potentials for Hydrocarbon Products from Electrochemical Reduction of CO on Cu (111). J Am Chem Soc 2016, 138 (2), 483-6.
14. Mathew, K.; Kolluru, V. S. C.; Mula, S.; Steinmann, S. N.; Hennig, R. G., Implicit self-consistent electrolyte model in plane-wave density-functional theory. J Chem Phys 2019, 151 (23), 234101.
15. Wang, V.; Xu, N.; Liu, J.-C.; Tang, G.; Geng, W.-T., VASPKIT: A user-friendly interface facilitating high-throughput computing and analysis using VASP code. Computer Physics Communications 2021, 267.
16. Knizia, G.; Klein, J. E., Electron flow in reaction mechanisms--revealed from first principles. Angew Chem Int Ed Engl 2015, 54 (18), 5518-22.
17. Deringer, V. L.; Tchougreeff, A. L.; Dronskowski, R., Crystal orbital Hamilton population (COHP) analysis as projected from plane-wave basis sets. J Phys Chem A 2011, 115 (21), 5461-6.
18. Kuo, T. C.; Tang, Y. T.; Cheng, M. J., How to Apply Quantum Mechanical Simulations to Study Electrochemical Catalysis. Chemistry(CSLT) 2020, 78 (2), 95-108.
19. Robin A. Cox, L. M. D., Adi E. Klausner, Tomasz A. Modro, Peter Wan, Keith Yate, Protonation acidity constants for some benzamides, acetamides, and lactams. Can. J. Chem. 1981, 59, 1568-1573.
20. Peterson, A. A.; Abild-Pedersen, F.; Studt, F.; Rossmeisl, J.; Nørskov, J. K., How copper catalyzes the electroreduction of carbon dioxide into hydrocarbon fuels. Energy & Environmental Science 2010, 3 (9).