| 摘要: | 這次所提出的三年期科技部計畫之目的，是以理論計算方法探討在不同的金屬或雙金屬、摻雜金屬以及石墨烯等表面之催化下，藉由透過可能的化學轉換使其能應用在綠能及感測材料的新發展。我們此次總共提出三個子計畫:(1)我們第一個子計畫之主題，係利用理論計算的方法去探討如何利用乙炔分子來協助抵抗SOFC陽極中貴金屬的硫毒化現象。而所選擇的反應方式就是利用乙炔來和已吸附在各貴金屬表面(純鎳、摻雜金屬或鎳合金)的硫原子進行化學反應，並嘗試找出形成硫雜環的化合物並達到去除硫毒化之目的。在固態氧化物燃料電池的應用中，當陽極鎳電極暴露在含有微量硫化氫的燃料進行電化學反應時，被分解所產生的硫原子會快速的將含鎳的電極毒化。因此我們第一個子計畫之主題，想嘗試利用上述的新方法來進行脫硫化反應，將藉由詳細的化應反應機制探討與進階的微觀現象分析，期許能發展出有效再生貴金屬催化活性的新方向。(2)利用高活性金屬和雙金屬作為催化劑並能有效地吸附並催化一氧化碳氣體是一個重要的課題。在甲醇燃料電池的應用中，其甲醇的氧化過程將會形成中間物一氧化碳，該CO分子會快速地毒化電極表面並阻礙甲醇燃料電池應用中的任何進一步反應。近期的文獻指出，甲醇燃料電池中的水分子很容易在金屬電極表面解離成羥基(OH)，預期該羥基或許可以與表面的CO進行反應並形成CO2氣體脫附，以消除電極毒化的現象。因此，我們第二個的子計畫主題將研究關於CO與OH分子在各種金屬/雙金屬表面進行催化反應，至於哪個金屬或雙金屬可以達到最好的效率，這將是我們必須全力去完成的主要任務。(3)在過去的文獻報導，石墨烯是一個不錯的氣體傳感器(gas sensor)，我們嘗試將石墨烯(graphene)摻入雜原子，例如：非金屬原子(N、B、S、Si)和金屬原子(Fe、Au、Pt、Cu、Pd、Ag)等，進行單取代、雙取代以及多取代等條件下，藉由電子局域函數分析(Electron Localization Function , ELF)、局部態密度分析(Local Density of States, LDOS)、Mulliken電荷分析以了解上述摻雜後石墨烯的新物理性質、化學性質及結構的變化。故關於第三個子計畫，我們希望能透過理論計算的方式去開發出新穎石墨烯的衍生物，並可以應用於超靈敏氣體感測器，液晶顯示器元件中的透明電極，鋰電池中的大容量電極等系統上。
The aim of this three years project is to explore the catalytic phenomena by applying the metallic, bimetallic, metal-doped, and graphene surfaces on the chemical reactions in which the reactants are those gases from the green/sustainable energy and sensor applications that related to our daily-life technologies. The project is divided into three sub-projects which deal with several practical chemical reactions; such as (1) By applying the DFT approach to explore the resistance of sulfur poisoning on Ni, metal doped, and alloy based surfaces with the assistance of acetylene molecules (HC≡CH). Our goal in this first project is to find the possible reaction mechanisms in each reaction in reaching the optimal catalytic effect provided by these highly active surfaces. As we know, trace amounts of sulfur in the hydrocarbon fuels would severely deactivate the above catalysts in SOFC applications. Therefore, the purposes of this first year project is to address the fully portray for the regeneration of precious-metal catalysts which may contribute to a sustainable solution of sulfur poisoning. (2) By utilizing the highly active metallic and bimetallic surfaces as catalysts to effectively adsorb the exhausted carbon monoxide (CO) gas is a very important topic. Especially, in the application of direct methanol fuel cell (DMFC), it is found that the toxic intermediate CO will be formed during the oxidation of methanol, leading to block the surface of the catalysts and hinder any further reaction in the DMFC application. Some literatures have found that the adsorbed OH species could directly react with adsorbed CO and form the desorbed CO2 gas, which could provide a significant method in the removal of surface CO through oxidation reaction. Therefore, this second year project will focus on calculating all possible reaction pathways of CO oxidation by the OH species on varied metal/bimetal catalysts. As to which metallic and bimetallic surfaces could do the best work, as well as the understanding of these complicated reaction mechanisms will be the main task that we have to overcome completely in this sub-project. (3) The substituting graphene with other atoms and metals such as N, B, S, Si, Fe, Au, Pt, Cu, Pd, Ag, and so on, could cause the enhancement in its electronic behavior for the advanced application of semi-conductor materials. Therefore, we want to understand effects of physical and chemical properties of adding one, two or more substituting atoms/metals on primitive graphene, trying to discuss its related absorption energies, optimized structures, electron localization function (ELF), local density of states (LDOS) and Mulliken populations. We hope this third year sub-project can be use as the applications of ultra-sensitive gas sensors, transparent electrodes in liquid crystal display, large capacity electrodes in Li batteries, and so forth. |
