全球暖化一直以來都是重要的環境議題，為了促進永續發展，近幾十年來，科學家們致力於將溫室氣體重新利用，使其轉變為我們日常所能使用的化合物，而其中最重要的方式為電化學催化使二氧化碳還原成甲烷、乙醇等有機化合物，並且也逐漸地往希望還原反應所得到的產物為較高經濟價值的雙碳甚至多碳產物邁進。若是要產生雙碳(C2)或多碳產物(C2+)，勢必要進行碳碳耦合反應(C-C coupling reaction)，即只要確定會進行碳碳耦合反應，便能夠產生較高經濟價值的C2+產物，因此本篇論文便以多碳產物的目標進行碳碳耦合反應路徑的研究。
本論文是以量子化學的方式利用動力學與熱力學計算出反應的活化能及反應熱來判斷反應進行的難易程度，在負電壓的環境下使用銅(110)切面進行碳碳耦合的反應探討。首先探討反應初期的碳碳耦合反應以及氫化反應的競爭關係，確立能夠進行的反應路徑為COCO的碳碳耦合，並且找出此二競爭反應的分界電壓為-0.64VSHE，即電壓比分界電壓負時，反應較易進行氫化反應，反之若電壓較分界電壓正時，則反應傾向於進行碳碳耦合反應。
我們選定了銅的另一個(111)切面來和(110)的切面進行比較及吸附能分析，也對其進行相同碳碳耦合路徑探討，發現其最佳路徑為CHOCHO耦合，這和實驗上發現銅(111)是容易產生C1產物的結果相符合，因為銅(111)無法進行COCO耦合，又很容易進行氫化反應，因此一被氫化就容易被直接被氫化成C1產物不太容易停留在CHO，因此進行CHOCHO耦合的機率就變低，導致其不易產生C2產物。
接著我們觀察後發現耦合的反應幾乎都發生在結構的x方向上，於是對x方向進行壓縮及擴張的表面變化，看表面變化是否對耦合反應及氫化反應有所影響，藉此可以達到降低活化能以促進反應或是改變分界電壓使我們有辦法更容易控制電壓及表面來得到我們所希望得到的C1或C2產物。
最後由於在實驗文獻中提到，當負電壓高過一定的值後，雙碳產物仍然有產生，若依照我們分界電壓的概念是無法解釋這一狀況，因此我們推測會有其他碳碳耦合路徑來產生C2產物。我們選定在-1.0VSHE時進行後續產生甲烷的C1路徑探討，並從此路徑中分析出其他六條碳碳耦合路徑，接著從這些路徑進行計算來找到在-1.0VSHE的電壓時若要產生雙碳產物應該進行的碳碳耦合路徑，就能完整確定在任意電壓下的碳碳耦合反應路徑。

Global warming is an important environmental issue in the recent years. Electrochemical catalysis method is one of the common way to reduce carbon dioxide to organic compounds, like methane or ethanol. In the last decade, more and more scientists wanted to get two-carbon or multi-carbon products, which had higher economic value, and this reaction must undergo C-C coupling reaction to get these compounds. Therefore, our research would focus on C-C coupling reaction to get multi-carbon products.

Based on quantum chemistry, this research judged the reaction rate by calculating thermodynamics and kinetics data (ΔG and ΔG‡). We choose Cu(110) surface to do C-C coupling reaction in negative voltage.

First, we find the best reaction pathway is COCO C-C coupling and the boundary voltage of hydrogenation and C-C coupling is -0.64VSHE. Second, we do the same analysis on Cu(111) to compare and analyze the adsorption energy with Cu(110). Third, we compressed and expansion x-direction to influence the ΔG‡ of C-C coupling reaction and the boundary voltage. Therefore, we can easily control surface and voltage to get C1 or C2 product. Finally, we predict that there will be another C-C coupling pathways to produce C2 products when voltage more negative than boundary voltage. Thus, we analyze C1 pathway to find the other six C-C coupling pathways at -1.0VSHE, finding that CHCH coupling is the best pathway. In conclusion, all C-C coupling pathways in any negative voltage have been investigated and the plausible pathways are identified.

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