以理論計算探索銅,鎳及銅鎳合金上含氮中間體對於 二氧化碳還原反應選擇性的影響

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Title:	以理論計算探索銅,鎳及銅鎳合金上含氮中間體對於二氧化碳還原反應選擇性的影響
Authors:	連惟新
Contributors:	化學工程與材料工程學系
Keywords:	理論計算
Date:	2023
Issue Date:	2024-03-01 15:32:27 (UTC+8)
Abstract:	由於近年來科技的進步，使的早期計算成本較高的合金催催化劑得以獲得大量的研究。單金屬催化劑的吸附位點單一，無法同時以理想的吸附能吸複雜原子中間體，相比單金屬催化劑雙金屬催化劑的潛力極大。此篇研究中我們透過密度泛涵理論(Density Functional Theory，DFT)研究表面Cu(111)、NiCu (111)、Ni(111) 對CORR和NO2RR相結合的雜原子催化路徑進行研究，反應路徑大致可分為:(1)二CO之間C-C成鍵、氫化產生COHCOH，經內轉換脫水形成CCO並與優先還原之的NH3進行C-N偶聯生成乙醯胺；(2) 二CO之間C-C耦合成鍵並氫化產生COHCOH但不與NH3偶聯，繼續氫化生成C2產物，如乙醇、乙二醇；(3)CO氫化至CH3OH。針對三種表面進行計算後發現Cu(111)表面比起COH更容易生成CHO，而CORR 途徑中 COH 中間體的形成會抑制C1的產生，因此比起Cu(111)表面， NiCu (111) 和 Ni(111) 表面會產生更多的 C2 產物。此外NiCu (111)為Ni(111)表層以Cu原子取代形成的表面，而少量 Cu 取代 Ni(111) 表面時，Ni 的活性將提高，這導致CO和NO2在NiCu(111)表面上的吸附能比Ni(111)更高。 Due to the recent advancement in technology, alloy catalysts with high computational cost in the early days have been extensively studied. Unlike monometallic catalysts, bimetallic catalysts have shallow potential energy surfaces and multiple adsorption sites, which allows for ideal adsorption energies for complex intermediates. In this study, we investigated the heteroatomic catalytic pathways for CORR and NO2RR on the surfaces of Cu(111), NiCu(111), and Ni(111) using Density Functional Theory (DFT). The reaction pathways can be roughly divided into: (1) C-C coupling between two CO molecules, hydrogenation to form COHCOH, internal conversion to produce CCO, and C-N coupling with preferentially reduced NH3 to generate acetamide; (2) C-C coupling between two CO molecules, hydrogenation to form COHCOH without coupling with NH3, and further hydrogenation to produce C2 products such as ethanol and ethylene glycol; (3) Over-hydrogenation of CO to CH3OH. After conducting calculations on the three surfaces, we found that Cu(111) surface is more likely to generate CHO than COH, and the formation of the COH intermediate in the CO2RR pathway inhibits the production of C1, resulting in more C2 products on NiCu(111) and Ni(111) surfaces compared to Cu(111). In addition, NiCu(111) is a surface formed by replacing some of the Ni atoms in the Ni(111) surface with Cu atoms, and a small amount of Cu substitution on the Ni(111) surface enhances the activity of Ni, leading to higher adsorption energies for CO and NO2 on NiCu(111) surface compared to Ni(111).
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