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利用分子动力学模拟研究了五种不同种类的溶质分子(K+,Mg2+,Cl-,K-和K0)在直径为0.60-1.28 nm的纳米碳管内的水化结构.模拟结果揭示了单电荷溶质、双电荷溶质和中性溶质在受限条件下具有不同的水化行为.单价溶质的配位数只有在直径不大于0.73 nm的纳米碳管内才会明显减少.和带有电荷的溶质不同,中性溶质的配位数对纳米碳管直径的改变非常敏感,并且随着管径的减小而迅速减少.模拟结果还表明带单价正电荷的溶质(K+)第一配位层水分子的取向结构会随着纳米碳管直径的改变发生变化,而其他溶质配位层取向结构在本文所涉及的纳米碳管内都几乎和体相中一致.在直径大于1.0 nm的纳米碳管中,K+的配位层取向结构有序度随着管径的减小而单调下降,但是在直径小于1.0 nm的纳米碳管中,随着碳管管径的减小而迅速上升.在两个最窄的纳米碳管内,其结构有序度甚至高于体相.双电荷溶质的水化结构在本文所研究的碳管直径范围内和体相完全一致,即使在直径只有0.6 nm的碳管内也无任何改变.
Molecular dynamics simulations were carried out to investigate the hydration structure of five different kinds of solute molecules (K +, Mg2 +, Cl-, K- and K0) in carbon nanotubes with a diameter of 0.60-1.28 nm. The simulation results revealed that the single charge solutes , Double charged solute and neutral solute have different hydration behavior under limited conditions.The coordination number of monovalent solute only decreases obviously in the carbon nanotube with the diameter of not more than 0.73 nm.Different from the charged solute, The coordination number of neutral solute is very sensitive to the change of carbon nanotube diameter and decreases rapidly with the decrease of tube diameter.The simulation results also show that the monovalent positively charged solute (K +) first coordination layer water molecules The orientation structure will change with the change of the diameter of carbon nanotubes, while the other solute coordination layer orientation structures are almost the same as the bulk phase in the carbon nanotubes involved in this paper.In the carbon nanotubes with diameters greater than 1.0 nm, K + The ordering degree of the coordination layer orientation monotonically decreases with the decrease of the tube diameter, but rapidly increases with the decrease of the tube diameter in the carbon nanotubes less than 1.0 nm in diameter. Carbon nanotubes, the order of its structure is even high Phase. Solute hydrated electric double structure in the carbon tube diameter range studied herein and phase exactly the same, even if the diameter of only 0.6 nm in the carbon tube is also without any change.