The Dissociated Amorphous Silica Surface: Model Development and Evaluation
The Dissociated Amorphous Silica Surface: Model Development and Evaluation
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DOI：
10.1021/ct100260z
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发表时间：
2010-11-01
影响因子：
5.5
通讯作者：
Singer, Sherwin J.
中科院分区：
文献类型：
--
作者：
Hassanali, Ali A.;Zhang, Hui;Singer, Sherwin J.
在pH 7时，无定形二氧化硅由于表面上的硅烷醇基团的去质子化而具有特征负电荷。器件中的电动现象和生物分子的传输敏感地依赖于表面形貌、离子和溶剂的分布以及双电层区域中靠近表面的溶质的吸附性质。因此，这些现象的模拟需要详细的原子模型的双层区域。在这篇文章中，我们扩展了我们的未解离的二氧化硅表面模型[J. Phys. Chem. B 2007，111，11181-11193]，以包括解离的Si-O-基团，其与水和盐（Na+和Cl-）相互作用。我们还进行了从头算分子动力学（AIMD）模拟一个较小的系统组成的水合二氧化硅板。经验模型预测的径向分布函数与AIMD模拟的径向分布函数定性一致。在我们的经验模型中观察到的无定形二氧化硅表面的硅醇贫乏和硅醇富集区域的疏水性和亲水性在较小平板的AIMD模拟中重现。在AIMD模拟的初始阶段，我们观察到代表表面不同羟基化机制的各种化学过程。
At pH 7, amorphous silica has a characteristic negative charge due to the deprotonation of silanol groups on the surface. Electrokinetic phenomena and transport of biomolecules in devices depend sensitively on the surface morphology, distribution of ions and solvent, and adsorption properties of solutes close to the surface in the electrical double layer region. Hence, simulation of these phenomena requires detailed atomistic models of the double layer region. In this Article, we extend our undissociated silica surface model [J. Phys. Chem. B 2007, 111, 11181-11193] to include dissociated Si-O- groups, which interact with both water and salt (Na+ and Cl-). We have also conducted ab initio molecular dynamics (AIMD) simulations of a smaller system consisting of a hydrated silica slab. The radial distribution functions predicted by the empirical model are in qualitative agreement with those from the AIMD simulations. The hydrophobic and hydrophilic nature of silanol-poor and silanol-rich regions of the amorphous silica surface observed in our empirical model is reproduced in the AIMD simulations of the smaller slab. In the initial stages of our AIMD simulations, we observe various chemical processes that represent different hydroxylation mechanisms of the surface.