A density functional theory study of CFb>3b>CHb>2b>I adsorption and reaction on Ag(111)

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• 作者：Bo-Tao Teng^a ; ^tbt@zjnu.cn ; Yue Zhao^a ; Feng-Min Wu^a ; Xiao-Dong Wen^b ; Qiao-Ping Chen^a ; Wei-Xin Huang^c ; ^{huangwx@ustc.edu.cn}
• 关键词：Density functional theory ; Ag(111) ; CF3CH2I ; Charge density difference ; Density of states
• 刊名：Surface Science
• 出版年：2012
• 期刊代码：104_00396028
• 类别：ch
• 出版时间：August, 2012
• 卷：606
• 期：15-16
• 页码：1227-1232
• 文件大小：1366 K

摘要

The adsorption and reaction behaviors of CFb>3b>CHb>2b>I on Ag(111) were systematically studied by density functional theory (DFT) calculations. Physical adsorption of CFb>3b>CHb>2b>I on Ag(111) occurs due to the weak interactions between surface Ag atoms and iodine atom of CFb>3b>CHb>2b>I; while strong chemisorption occurs for CFb>3b>CHb>2b> fragment on Ag(111). Electronic analysis indicates that the singly occupied molecular orbital (SOMO) of CFb>3b>CHb>2b> strongly interacts with the surface Ag atoms. It is very interesting to find that the most stable structures of CFb>3b>CHb>2b> on Ag(111) locate at the top site, instead of the hollow sites. This might be attributed to the facts that CFb>3b>CHb>2b> adsorbed at the top site will maximize the sp³-type hybridization, and the possible weak interaction between the fluorine lone pair electrons of p orbitals for CFb>3b>CHb>2b> and surface Ag(111) occurs, which is supported by the charge density difference (CDD) analysis with a low isosurface value. We propose that the charge density difference (CDD) analysis with a high or low isosurface value can be widely applied to analyze the strong or weak electronic interactions upon adsorption. Transition state calculations suggested that the energy barrier of CF bond rupture for CFb>3b>CHb>2b>I on Ag(111) (1.44 eV) is much higher than that of CI bond breakage for CFb>3b>CHb>2b>I (0.43 eV); and the activation energy of the CF bond dissociation for CFb>3b>CHb>2b>(a) is 0.67 eV.