本論文研究旨在以第一原理計算設計同質非等向晶面半導體，加上助催化劑，進行人工光合作用，並專注於光陽極的產氧分析。迄今為止，光催化反應的效率仍然很低，歸因於兩大原因，第一為電荷分離效率低，因為光激發產生的電子和電洞極容易重新再結合;第二是由於產氧反應的高過電勢障礙，產氧需要更高的能量才能克服動力學障礙，因此如何克服上述兩大挑戰對於可再生能源儲存和轉換系統設計至關重要。本文所選用之光觸媒鈦酸鍶(SrTiO3)具有良好的能帶特性，低成本，高抗光腐蝕和抗化學腐蝕的能力，一直是最廣泛的光催化分解水半導體之一，本研究提出設計簡單同質非等向性晶面半導體，再搭配光電催化活性相當優越助催化劑CoOOH，進一步提升光電產氧效率。
本研究先將鈣鈦礦結構的SrTiO3立方晶體與菱面體CoOOH透過密度泛函理論(DFT)尋求最穩定結構，並進一步進行物理性質和光學性質計算，以取得能帶結構、電子態密度、反射率R 及吸收光譜α等光學性質，再利用上述的光學性質數值分析內建電場、導價帶特徵值。緊接著CoOOH晶體表面上執行產氧氧化半反應的模擬、並導入氧空缺的概念，達到降低過電勢與活化能的目標。
根據第一原理計算，藉由異質界面建構分析SrTiO3能帶彎曲，內建電場的值為不同晶面平均位勢值之差值，模擬結果為2.913 eV，與運用功函數差值方式相較，誤差約為5.39％，證明藉由高內建電位，電子和電洞可有效地轉移到不同的非等向平面以完成光氧化和還原反應。由態密度(density of states)也顯示，在SrTiO3 (110)與(100)形成非等向晶面後，由於內建電場連帶能帶偏移，(110)之價帶和導帶會高於(100)，表明(110)和(100)分別扮演p型和n型半導體角色。再從本論文四種析氧結果，顯示本論文提出建立氧空位提高電導率的方式，會造成結構相對不穩定，進而促進水分子在活性位點上的吸附，提升整個產氧催化效率。

This thesis uses first principles calculation to design an anisotropic facets semiconductor as a photoanode to generate the oxygen evolution reaction (OER) in the artificial photosynthesis system. So far, the efficiency of photocatalytic reactions is still very low due to low charge separation efficiency and high overpotential barriers during the process of OER. Therefore, this research proposed a simple homogeneous anisotropic facets semiconductor Strontium Titanate (SrTiO3) coupled with a cocatalyst CoOOH to further improve the efficiency of photoelectrical plant for oxygen production
In this study, the perovskite structure of SrTiO3 cubic crystals and rhombohedral CoOOH were used to find the most stable structure through density functional theory (DFT). After further calculation of physical and optical properties, the built-in electric field as well as valence band and conduction band were evaluated by using the above values of optical properties. Then, the simulation of oxidation half reaction was performed on the surface of the CoOOH crystal and the concept of oxygen vacancy was introduced to achieve the goal of reducing the activation overpotential.
It was found that the formation of the facet junction is verified by a calculated work function difference between the (110) and (100) planes, which formed p-type and n-type segments of the junction, respectively. The built-in potential was estimated at about 2.9 V. As a result, with the ultra high built-in potential, electrons and holes can effectively transfer to different anisotropic planes to complete both photo-oxidative and photo-reductive reactions. The proposed oxygen vacancy technique has also been proved that establishing oxygen vacancies to increase conductivity promoted the adsorption of water molecules on active sites, reduced the activation overpotential and improved the overall efficiency of OER.

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