油酸钠在锡石(211)表面吸附的量子化学研究

Quantum Chemical Study of the Adsorption of NaOL on Cassiterite(211) Surface

通过密度泛函理论计算研究了油酸钠在锡石(211)表面上的吸附机理.通过模拟XRD图谱与实测XRD图谱验证了建立的锡石晶胞结构的合理性.收敛性测试结果表明,当锡石(211)表面结构厚度超过5.437×10^(-10)m,真空层深度大于10×10^(-10)m时,表面结构趋于稳定.吸附能计算显示H_2O和OH-可以自发地吸附在(211)表面上,然而OL-在(211)表面上的吸附能最低,可以取代被吸附的H_2O和OH-.M ulliken电荷布局计算和差分电子密度分析表明,反应过程中油酸羧基中的两个O原子与锡石表面裸露的Sn原子之间通过化学键形成化学吸附,其中单键O与Sn原子形成的化学键键强更大.

The adsorption of Na OL on cassiterite（ 211） surface was studied by first-principles calculations based on density functional theory. The rationality of the simulated cassiterite bulk cell was confirmed by comparing the numerical and experimental XRD patterns. Stypticity test results showthat cassiterite（ 211） surface is stable when the slab thickness exceeds 5. 437 × 10^-10m and the vacuum depth surpasses 10 × 10^-10m. Adsorption energy calculation results suggest that H2O and OH-can adsorb on the（ 211） surface spontaneously,but the affinity of OL-with cassiterite（ 211） surface is the strongest,implying it can replace the adsorbed H2O and OH-species on（ 211） surface. Mulliken charge calculations and differential electron density analyses demonstrate the two O atoms in oleate carboxyl are bonded with two exposed Sn atoms on the surface during the interaction,resulting in chemisorption with the stronger bond formed by the single bond O and Sn atom.