论文标题
在水溶液中裸金（AU）纳米颗粒上的离子特异性吸附：双层结构和表面电势
Ion-specific Adsorption on Bare Gold (Au) Nanoparticles in Aqueous Solution: Double-Layer Structure and Surface Potentials
论文作者
论文摘要
我们研究裸金（AU）纳米颗粒（NPS）的溶剂化和静电性能，为$ 1 $ - $ 2 $ 2 $ NM的大小，用于各种阴离子的钠盐水溶液溶液，具有较大的物理化学多样性（Cl $^ - $^ - $，bf $ _4 $ _4 $ _4 $ _4 $ _4 $ _4 $ _4 $ _6 $ _6 $ _6 $ _6 $ _6 $^ - $^ - 和）使用不可极化的，经典的分子动力学计算机模拟的4价己酰甲甲酸（HCF））。我们在Au-nps的离子的吸附结构和空间分布中发现了很大的相位选择性：而钠和某些阴离子（例如Cl $^ - $，HCF $，HCF $^{3 - } $）在“ Edggy'（Edgygy'（100）和（100）和（110）的NPS结构中，更多的水水水合物（E. bf $ _4 $$^ - $，pf $ _6 $$^ - $，nip $^ - $）更喜欢在扩展而固定的（111）方面强烈地吸附。特别是，nip $^ - $，具有化学结构中的芳族环，强烈吸附，并在NP（111）方面占据了第一个水单层结构。此外，我们通过映射计算出的静电势分布的远距离衰减来计算吸附，径向分辨的静电电势以及远场有效的静电表面电荷和电位。我们展示了这些值如何通过有效的表面电荷与电位之间的分析吸附 - 格子关系来执行其他离子强度。我们发现所有盐的负有效表面电势从$ -10 $ MV的NACL降至Nanip的$ -80 $ MV，这与Zeta-Postential的典型实验范围一致。我们讨论了这些值如何取决于表面定义，并将其与NP表面附近的明确计算的静电电势进行比较，NP表面在$ \ pm 0.5 $ V范围内具有很高的振荡性。
We study the solvation and electrostatic properties of bare gold (Au) nanoparticles (NPs) of $1$-$2$ nm in size in aqueous electrolyte solutions of sodium salts of various anions with large physicochemical diversity (Cl$^-$, BF$_4$$^-$, PF$_6$$^-$, Nip$^-$(nitrophenolate), 3- and 4-valent hexacyanoferrate (HCF)) using nonpolarizable, classical molecular dynamics computer simulations. We find a substantial facet selectivity in the adsorption structure and spatial distribution of the ions at the Au-NPs: while sodium and some of the anions (e.g., Cl$^-$, HCF$^{3-}$) adsorb more at the `edgy' (100) and (110) facets of the NPs, where the water hydration structure is more disordered, other ions (e.g., BF$_4$$^-$, PF$_6$$^-$, Nip$^-$) prefer to adsorb strongly on the extended and rather flat (111) facets. In particular, Nip$^-$, which features an aromatic ring in its chemical structure, adsorbs strongly and perturbs the first water monolayer structure on the NP (111) facets substantially. Moreover, we calculate adsorptions, radially-resolved electrostatic potentials, as well as the far-field effective electrostatic surface charges and potentials by mapping the long-range decay of the calculated electrostatic potential distribution onto the standard Debye-Hückel form. We show how the extrapolation of these values to other ionic strengths can be performed by an analytical Adsorption-Grahame relation between effective surface charge and potential. We find for all salts negative effective surface potentials in the range from $-10$ mV for NaCl down to about $-80$ mV for NaNip, consistent with typical experimental ranges for the zeta-potential. We discuss how these values depend on the surface definition and compare them to the explicitly calculated electrostatic potentials near the NP surface, which are highly oscillatory in the $\pm 0.5$ V range.
