| 摘要: | 隨著工業發展，環保意識抬頭，許多人致力於實現環境永續發展，因此，減少工業發展產生的汙染物便成了重要的議題。光觸媒經常應用於環境汙染物的降解，因為具有低成本、效率高等特性，因此光觸媒的發展備受矚目。而二氧化鈦因其無毒、穩定、成本低廉、豐饒等特性成為最受關注的光觸媒材料，因此本研究通過第一原理計算探討二氧化鈦表面改質的特性，以期二氧化鈦能具有更廣泛的應用。
在這項研究中，我們討論了三種不同的結構，分別為未經改質的銳鈦礦 (101) 面、銅團簇吸附的銳鈦礦 (101) 面以及銅鐵雙金屬團簇吸附的銳鈦礦 (101) 面，並探討三種結構的電子結構、甲醇的吸附位點及甲醇的解離機制。模擬計算的結果表明，吸附金屬的銳鈦礦 (101) 面具有較小的帶隙，銅團簇吸附的銳鈦礦 (101) 面的帶隙為1.579 eV，銅鐵雙團簇吸附的銳鈦礦 (101) 面的帶隙為1.527 eV。意即經改質的銳鈦礦 (101) 面的應用範圍將不再受限於紫外光，拓展其應用於可見光和紅外光的環境。值得注意的是，雙金屬團簇改質的銳鈦礦 (101) 面具有較好的縮小帶隙的效應。此外，甲醇的光催化製氫反應也是光觸媒熱門的應用之一，因此甲醇的解離機制也是我們的研究重點，探討金屬團簇的改質是否具有降低甲醇解離反應能障的效應。本研究首先測試銳鈦礦 (101) 表面上所有可能的甲醇吸附位點，並經由結構優化的計算結果確定甲醇吸附於三種結構上最穩定的構型。接著進一步計算甲醇於三種不同結構上的解離機制，甲醇的解離分為兩步驟，雖然經金屬團簇改質的銳鈦礦 (101) 面於第二步都具有略高的能障，但第一步的甲醇解離能障於銅鐵團簇改質的銳鈦礦 (101) 面有變小的效應，這有利於甲醇解離反應的進行。
;With the development of industry, the issue of environmental pollution is becoming an increasingly important issue that cannot be ignored. Many people are devoted to the sustainable development of the environment, therefore, the reduction of pollutants generated by industrial development has become an important issue. Photocatalysts are often used in the degradation of environmental pollutants, because of its low cost and high efficiency, so the development of photocatalysts has attracted much attention. Titanium dioxide is the most popular photocatalyst material because of its non-toxic, stable, low cost, and abundant. Therefore, this study investigates the properties of titanium dioxide modification by first principle calculations with the purpose of titanium dioxide having a wider application.
In this study, we discussed three different structures, pristine TiO2(101), Cu5/TiO2(101), and Cu4Fe/TiO2(101), and investigated the electronic structure, methanol adsorption sites, and methanol dissociation mechanism of the three structures. The results of the calculations show that TiO2(101) adsorbed with metal clusters have a smaller band gap of 1.579 eV for Cu5/TiO2(101) and 1.527 eV for Cu4Fe/TiO2(101). This means that the application of modified TiO2(101) surface is no longer limited to ultraviolet light, but expands its application to the visible and infrared light environment. It is worth noting that the bimetallic cluster-modified TiO2(101) shows a better band gap reduction effect. In addition, the photocatalytic hydrogen production reaction of methanol is one of the popular applications of photocatalysts, so the dissociation mechanism of methanol is the main concern of our study to investigate whether the TiO2(101) modification by adsorption of metal clusters has the effect of reducing the energy barrier of methanol dissociation reaction. In this study, all the possible methanol adsorption sites on TiO2(101) were tested and the most stable methanol adsorption configurations on the three structures were determined by geometry optimization calculations. Then, the dissociation mechanism of methanol on the three different structures was calculated. The dissociation mechanism of methanol is divided into two steps. Although TiO2(101) modified by metal clusters has a slightly higher energy barrier in the second step, the energy barrier in the first step has a smaller effect on Cu4Fe/TiO2(101), which facilitates the dissociation reaction of methanol. |
