本研究旨在利用量子模擬探討人工光合作用中陰極催化二氧化碳(CO2)還原成碳氫燃料的過程，希望能詳盡的了解整個反應，並找出會遇到的問題，以求改善方案。選用的陰極材料為摻鋁的紫質基金屬有機框架(Al-PMOF)，此類催化劑在研究中被證實能夠將二氧化碳催化還原為甲酸(HCOOH)或者甲醇(CH3OH)；主要使用的模擬軟體為根據計算量子化學設計的Gaussian09，輔以B3LYP理論及基底函數6-31G(d,p)；次要的模擬軟體則是由蒙地卡羅理論所設計的Adsorption Locator。
　　研究中，透過Adsorption Locator預測加入的二氧化碳與氫離子(H+)的位置，並透過Gaussian09對預測所得到的結構做更加嚴謹的結構最佳化、過渡態計算、內反應座標確認，最終我們確定了Al-PMOF催化二氧化碳還原甲酸以及甲醇的反應路徑及其各步驟反應速率常數：催化劑Al-PMOF的最佳化結構幾何誤差與實驗值相比最大不超過3%且光學性質相符；二氧化碳在催化初期會被折彎成具有112.424o角度的結構，對於降低結構穩定性與增加催化發生的可能性有重要的影響；整個催化過程為釋能反應，由吸附二氧化碳並催化至析出甲酸的結構共需提供3.306 eV的能量並會釋放出1.19 Ha的能量，至析出甲醇則需提供7.315 eV的能量，並會釋放出3.60 Ha的能量；在加入第四個氫離子催化完成後，會產生一個水分子，若其脫離反應區，後續的催化便會難以生成穩定的產物；整個反應中，加入第一個(k2 = 2.233×10-11 s-1)、第五個(k6 = 2.055×10-10 s-1)氫離子，以及析出甲醇(k8 = 3.736×10-10 s-1)時的速率常數較小。
　　最後本研究認為欲改善現下催化二氧化碳成甲醇時所遇到效率低落的問題，除了尋找更有效的陰極，亦可以從以下部分著手：(1)設計能夠通入二氧化碳且能同時保持陰極反應區流場穩定的反應裝置，確保水分子不會脫離反應區致使反應無法順利進行；(2)各步驟間反應速率常數的差異略大，尋找有效的助催化劑出來改善反應速率較慢步驟亦可大幅提升整體效率。

　　This thesis aims to use quantum simulation to study the process of CO2 reduction to hydrocarbon fuel at the cathode in the artificial photosynthesis. The selected cathode catalyst is porphyrin-based metal organic framework (Al-PMOF). The main simulation software uses Gaussian09, which is designed according to the computational quantum chemistry. In the first principles calculation, B3LYP theory and the basis function 6-31G(d,p) were chosen. The secondary simulation software is the Adsorption Locator which based on Monte Carlo algorithms and empirical potential functions.
　　We simulated the reaction pathway and calculated the reaction rate constant (k) of the CO2 reduction reaction to HCOOH and CH3OH at the Al-PMOF catalyst. The geometric error of the Al-PMOF model is less than 3% compared with the experimental results. All the optical properties are consistent with measurements. CO2 will be bent into a structure with an angle of 112.424o at the initial stage of catalysis, which has an important influence on reducing structural stability and increasing the possibility of catalytic reaction. The overall reaction is exergonic that when producing HCOOH, 3.306 eV is required and 1.190 Ha will be released. When producing CH3OH, 7.315 eV is required and 3.600 Ha will be released. When the fourth hydrogen ion is catalyzed, a water molecule is produced. If the water molecule leaves away the reaction zone, it will be difficult to produce stable products later. The first (k2 = 2.233×10-11 s-1), fifth (k6 = 2.055×10-10 s-1) hydrogen ions and CH3OH precipitation (k8 = 3.736×10-10 s-1) steps have the slowest reaction rate constant, which is designated as the rate determined step. In summary, this study proposes two ways to improve the efficiency of CH3OH production from CO2: (a) Design a stable flow field reactor to prevent H2O molecules from leaving the reaction zone; (b) Look for some effective co-catalysts to help the reaction complete more quickly.

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