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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。
The effect of sodium salicylate on the surface of goethite or hematite was investigated by Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and periodic wave-based density functional theory (DFT) , And the calculated photoelectron spectrum shift (CLS) and charge transfer were compared with the experimental XPS results. FT-IR results show that sodium salicylate may adsorb on the surface of goethite or hematite respectively in the form of bidentate binuclear (V) and bidentate mononuclear (IV). From the results of DFT calculation, the adsorption energy of sodium salicylate to form bidentate binuclear compound (V) on the (101) crystal surface of goethite is -5.46 eV. However, the adsorption energy of sodium salicylate to form bidentate mononuclear compound (IV) on the (101) crystal surface of goethite is 3.80 eV. Therefore, sodium salicylate does not basically contain bidentate mononuclear compound (IV) configuration exists. The adsorption energy of sodium salicylate is -4.07 e V when the bidentate mononuclear complex (IV) is formed on the (001) crystal surface of hematite, indicating that sodium salicylate forms bis Teeth Mononuclear Compound (IV). In addition, the calculated CLS value (-0.68 eV) of Fe 2p at the iron atom adsorbed on the (101) crystal surface of goethite coincides with the experimentally observed CLS value (-0.5 eV) of Fe 2p. The CLS value (-0.80 eV) of Fe 2p at the iron atom adsorbed on the (001) crystal plane of the hematite coincides with the observed CLS value (-0.8 eV) of Fe 2p. Therefore, sodium salicylate adsorbed on the surface of goethite can form bidentate dinuclear (V) through the oxygen atom of one oxygen atom and phenolic hydroxyl group on the carboxylic acid group and two iron atoms on the surface of goethite (101) ) Structure, and on the (001) surface of hematite, the oxygen atom on the one oxygen atom and the phenolic hydroxyl group of the carboxylic acid group in the sodium salicylate forms an iron double bond with one iron atom on the (001) hematite surface Tooth mononuclear (IV) structure.