利用理論計算方法探討H2O於W@Fe(111)和Fe(111)表面之吸附與分解行為

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Title:	利用理論計算方法探討H2O於W@Fe(111)和Fe(111)表面之吸附與分解行為 Adsorption and Dissociation Behaviors of H2O on the W@Fe(111) and Fe(111) Surfaces: A Computational Study
Authors:	鍾居翰 Chong, Chu-Han
Contributors:	化學系應用化學碩士班
Keywords:	H2O於表面 H2O on the W@Fe(111)
Date:	2015-12-28
Issue Date:	2016-01-27 11:24:11 (UTC+8)
Abstract:	在這篇研究中，我們通過自旋極化密度函數理論來計算H2O在Fe(111)和W@Fe(111)表面進行的解離反應，H2O、OH、O和H在兩種金屬表面上的穩定吸附結構，在Fe(111)分別為(T-η1-O)、(T,T-μ2-O)、(T,S-μ2-O)和(S-η1-H)，而在W@Fe(111)表面則分別為(T-η1-O)、(T-η1-O)、(T-η1-O)和(S-η1-H)。另外對H2O在兩種表面上解離的吸附能作了分析，在Fe(111)表面上，H2O的吸附能為 -7.88 kcal/mol，解離後的O及H的吸附能為 -277.99 kcal/mol，在W@Fe(111)表面上時，H2O的吸附能為 -13.14 kcal/mol，解離後的O及H的吸附能為 -304.86 kcal/mol，而H2O在兩個表面上脫氫的能障分別為 -4.14 kcal/mol以及 -13.40 kcal/mol，OH在兩個表面上脫氫的能障分別為 -39.34 kcal/mol以及 -27.59 kcal/mol。再藉由LDOS的分析得知，表面的d軌域和氣體分子的未鍵結軌域及反鍵結軌域間均有明顯的交互作用力，H2O與W@Fe(111)表面的混成現象(Hybridization)與Fe(111)相比較顯著。由上述方法來分析吸附物與表面在催化過程中的相互作用。 The adsorption and dehydrogenation behaviors of water on Fe(111) and W@Fe(111) surfaces have been studied by employing spin-polarized density function theory calculations. In this work, three possible adsorption sites of the Fe(111) and W@Fe(111) surfaces were obtained, such as (T-η1-O), (T,T-μ2-O), (T,S-μ2-O) and (S-η1-H) sites for Fe(111), and (T-η1-O), (T-η1-O),(T-η1-O) and (S-η1-H) sites for W@Fe(111) counterpart. The highest adsorption energy of H2O on aforementioned surfaces are calculated to be -7.88 and -13.14 kcal/mol for Fe(111) and W@Fe(111) surface, respectively, and the corresponding dehydrogenation processes were also predicted. The calculated activation energies for H2O dehydrogenations on Fe(111) and W@Fe(111) surfaces are -4.14 kcal/mol and -13.40 kcal/mol, respectively. In addition, the further dehydrogenations for OH are -39.34 kcal/mol and -27.59 kcal/mol, respectively. To gain more insights into catalytic processes of the aforementioned conducts, the interaction nature between the adsorbate and substrate is analyzed via detailed electronic analysis.
Appears in Collections:	[Department of Chemistry & Graduate Institute of Applied Chemistry ] thesis

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