Molybdenum(VI) Adsorption onto Lepidocrocite (γ-FeOOH): In Situ Vibrational Spectroscopy and DFT+U Theoretical Study,The Journal of Physical Chemistry C

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Molybdenum(VI) Adsorption onto Lepidocrocite (γ-FeOOH): In Situ Vibrational Spectroscopy and DFT+U Theoretical Study
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2016-05-24 00:00:00 , DOI: 10.1021/acs.jpcc.6b00722
A. Davantès ₁ , D. Costa ₁ , G. Lefèvre ₁

Affiliation

In situ polarized ATR-FTIR spectroscopy and the DFT+U calculations were used to investigate the Mo(VI) ions surface speciation on lepidocrocite. Adsorption of molybdate ions is found to be tetrahedral monodentate binuclear (C_3v) on the (010) face. DFT+U calculations were performed to help characterizing the geometries of the complexes adsorbed to assign the vibrational frequencies and get insight into the energies of adsorption. The (010) surface was chosen as a model of lepidocrocite surface. Calculations are consistent with the sorption of MoO₄^2– ions to form a monodentate complex at basic pH. This complex is protonated when the surface coverage increases, and the pH decreases. At the full coverage, calculations show alternate monodentate protonated binuclear complexes and surface hydroxyl groups. Moreoever, the formation of hydrogen bonds with the surface hydroxyls and between adsorbed complexes plays an important role in the structure stability.

中文翻译：

钼（VI）吸附在纤铁矿（γ-FeOOH）上：原位振动光谱法和DFT + U理论研究

原位极化ATR-FTIR光谱和DFT + U计算用于研究纤铁矿上Mo（VI）离子的表面形态。发现钼酸盐离子的吸附是（010）面上的四面体单齿双核（C _{3 v}）。进行了DFT + U计算，以帮助表征被吸附的配合物的几何形状，从而确定振动频率，并深入了解吸附的能量。选择（010）表面作为纤铁矿表面的模型。计算结果与MoO ₄^2–的吸附一致离子在碱性pH下形成单齿复合物。当表面覆盖率增加，pH降低时，该复合物就会质子化。在全部覆盖范围内，计算结果显示了交替的单齿质子化双核络合物和表面羟基。此外，与表面羟基以及被吸附的配合物之间形成氢键在结构稳定性中起重要作用。

更新日期：2016-05-24

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