采用傅里叶变换红外(FT-IR)光谱、X射线光电子能谱(XPS)以及基于周期平面波的密度泛函理论(DFT)分别研究了水杨酸钠在针铁矿或赤铁矿表面上的吸附结构,并将计算得到的光电子能谱移动(CLS)和电荷转移与实验得到的XPS结果进行对比。FT-IR...采用傅里叶变换红外(FT-IR)光谱、X射线光电子能谱(XPS)以及基于周期平面波的密度泛函理论(DFT)分别研究了水杨酸钠在针铁矿或赤铁矿表面上的吸附结构,并将计算得到的光电子能谱移动(CLS)和电荷转移与实验得到的XPS结果进行对比。FT-IR结果表明,水杨酸钠可能以双齿双核(V)和双齿单核(IV)的形式分别吸附于针铁矿或赤铁矿表面。由DFT计算结果可知,水杨酸钠在针铁矿(101)晶面上形成双齿双核化合物(V)的吸附能为-5.46 e V。而水杨酸钠在针铁矿(101)晶面上形成双齿单核化合物(IV)的吸附能为3.80 e V,因此水杨酸钠在针铁矿上基本不以双齿单核化合物(IV)构型存在。水杨酸钠在赤铁矿(001)晶面上形成双齿单核化合物(IV)时吸附能为-4.07 e V,说明水杨酸钠在赤铁矿(001)晶面上形成了双齿单核化合物(IV)。另外,理论计算的针铁矿(101)晶面上吸附位点铁原子的Fe 2p的CLS值(-0.68 e V)与实验观察到的Fe 2p的CLS值(-0.5 e V)吻合。理论计算的赤铁矿(001)晶面上吸附位点铁原子的Fe 2p的CLS值(-0.80 e V)与实验观察到的Fe 2p的CLS值(-0.8 e V)吻合。因此,水杨酸钠吸附在针铁矿表面时能够通过羧酸基团上一个氧原子和酚羟基上的氧原子与针铁矿(101)表面上的两个铁原子形成双齿双核(V)结构,而在赤铁矿(001)表面上,水杨酸钠中羧酸基团上一个氧原子和酚羟基上的氧原子与赤铁矿(001)表面上的一个铁原子形成了双齿单核(IV)结构。展开更多
Using the M 4(M=Ru, Rh, Pd) clusters as models, chemisorption of CO at the top and bridge sites has been performed by Gaussian programs, at the DFT/LANL1DZ level. Metal CO bonding and the influence of CO bond after ch...Using the M 4(M=Ru, Rh, Pd) clusters as models, chemisorption of CO at the top and bridge sites has been performed by Gaussian programs, at the DFT/LANL1DZ level. Metal CO bonding and the influence of CO bond after chemisorption CO have been studied, and the effects on the products of CO hydrogenation have been inferred. The calculations have shown that all the CO bonds are wakened after adsorption. Ru catalyst weakens C-O bond the most largely, Pd weakens C-O bond the least, and Rh lies between them. So it could be concluded that the products of CO hydrogenation have a trend to the hydrocarbons over the Ru catalyst, and the products are inclined to oxygenate over Pd, while there isnt obvious trend to the hydrocarbons and oxygenate on Rh.展开更多
基金supported by the National Natural Science Foundation of China (51134007, 51174231)~~
文摘采用傅里叶变换红外(FT-IR)光谱、X射线光电子能谱(XPS)以及基于周期平面波的密度泛函理论(DFT)分别研究了水杨酸钠在针铁矿或赤铁矿表面上的吸附结构,并将计算得到的光电子能谱移动(CLS)和电荷转移与实验得到的XPS结果进行对比。FT-IR结果表明,水杨酸钠可能以双齿双核(V)和双齿单核(IV)的形式分别吸附于针铁矿或赤铁矿表面。由DFT计算结果可知,水杨酸钠在针铁矿(101)晶面上形成双齿双核化合物(V)的吸附能为-5.46 e V。而水杨酸钠在针铁矿(101)晶面上形成双齿单核化合物(IV)的吸附能为3.80 e V,因此水杨酸钠在针铁矿上基本不以双齿单核化合物(IV)构型存在。水杨酸钠在赤铁矿(001)晶面上形成双齿单核化合物(IV)时吸附能为-4.07 e V,说明水杨酸钠在赤铁矿(001)晶面上形成了双齿单核化合物(IV)。另外,理论计算的针铁矿(101)晶面上吸附位点铁原子的Fe 2p的CLS值(-0.68 e V)与实验观察到的Fe 2p的CLS值(-0.5 e V)吻合。理论计算的赤铁矿(001)晶面上吸附位点铁原子的Fe 2p的CLS值(-0.80 e V)与实验观察到的Fe 2p的CLS值(-0.8 e V)吻合。因此,水杨酸钠吸附在针铁矿表面时能够通过羧酸基团上一个氧原子和酚羟基上的氧原子与针铁矿(101)表面上的两个铁原子形成双齿双核(V)结构,而在赤铁矿(001)表面上,水杨酸钠中羧酸基团上一个氧原子和酚羟基上的氧原子与赤铁矿(001)表面上的一个铁原子形成了双齿单核(IV)结构。
文摘Using the M 4(M=Ru, Rh, Pd) clusters as models, chemisorption of CO at the top and bridge sites has been performed by Gaussian programs, at the DFT/LANL1DZ level. Metal CO bonding and the influence of CO bond after chemisorption CO have been studied, and the effects on the products of CO hydrogenation have been inferred. The calculations have shown that all the CO bonds are wakened after adsorption. Ru catalyst weakens C-O bond the most largely, Pd weakens C-O bond the least, and Rh lies between them. So it could be concluded that the products of CO hydrogenation have a trend to the hydrocarbons over the Ru catalyst, and the products are inclined to oxygenate over Pd, while there isnt obvious trend to the hydrocarbons and oxygenate on Rh.
