發(fā)布時間：2018-08-13 09:01

【摘要】：單錐形納米孔道由于具有對稱性破缺和表面電荷特性而表現出整流效應,因此在離子分離、電能供應、化學閥等領域具有重要的潛在應用價值。深入研究納米孔道中的電學特性及納米孔道修飾方法,對于理解納米尺度下的離子輸運特性和改進錐形納米孔道應用性能具有重要的意義。本文基于蘭州交叉學科重離子微束裝置的單離子輻照技術,用單個離子輻照PET薄膜樣品,通過化學蝕刻單離子徑跡的方法成功制備出了單錐形納米孔道,并測量了多種電解質溶液在單錐形納米孔道中的離子輸運特性。研究發(fā)現,在KCl、NaCl、LiCl、MgCl_2、CaCl_2五種不同的溶液中均可以觀測到單錐形納米孔道的整流效應,并且整流系數都隨溶液濃度增加呈現先增大后減小的趨勢;相比于一價電解質溶液,二價電解質溶液中整流系數在較低濃度下就能達到最大值。對此我們提出了單錐形納米孔道內的離子輸運模型,該模型考慮了溶液濃度、施加電壓以及離子富集引起納米孔內的勢阱的變化,成功解釋了觀察到的實驗現象。為了對整流效應有更深入的理解,我們進一步對單錐形納米孔道的離子選擇性進行了研究。我們設計實驗實現了單錐形納米孔道內離子的單向輸運測試,通過陰陽離子電流大小可以確定單錐形納米孔道的陰陽離子選擇性。我們發(fā)現PET單錐形納米孔道在多價陽離子溶液中浸泡會使其表面由負電荷態(tài)轉變?yōu)檎�電荷態(tài),進而導致其由陽離子選擇性轉變?yōu)殛庪x子選擇性。我們繼續(xù)研究了多價陽離子使單錐形納米孔道表面電荷反轉的過程,發(fā)現其表面電荷反轉主要是由于多價陽離子在孔壁上的吸附,并且受到電解質溶液濃度的影響。數據顯示,三價離子溶液中的電荷反轉濃度小于二價離子,而一價離子溶液中未觀測到表面電荷反轉。
[Abstract]:Single conical nanochannels exhibit rectifying effects due to their symmetry breaking and surface charge characteristics, so they have important potential applications in the fields of ion separation, power supply, chemical valves and so on. It is of great significance to study the electrical properties and the modification methods of nanorods in order to understand the ion transport characteristics in nanoscale and improve the application performance of conical nanochannels. Based on the single ion irradiation technique of Lanzhou interdiscipline heavy ion microbeam device, single conical nanorods were successfully prepared by chemical etching of single ion track in PET thin film samples irradiated by single ion. The ionic transport characteristics of various electrolyte solutions in a single conical nano-channel have been measured. It is found that the rectifying effect of single conical nano-channel can be observed in five different solutions of KCl-NaCl-LiCl-MgCl-2CaCl2, and the rectifying coefficient increases first and then decreases with the increase of solution concentration, compared with the monovalent electrolyte solution, The rectifying coefficient in bivalent electrolyte solution can reach the maximum at lower concentration. In this paper, we present an ion transport model in a single conical nano-channel. The model takes into account the changes of the potential trap in the nano-pore caused by solution concentration, applied voltage and ion enrichment, and explains the observed experimental phenomena successfully. In order to better understand the rectifying effect, we have further studied the ion selectivity of single conical nano-channels. The unidirectional transport test of ions in a single conical nano-channel has been carried out. The anion selectivity of a single conical nano-channel can be determined by the current of anion and anion. We find that immersion of PET mono-conical nano-channels in polyvalent cationic solution can change the surface of PET from negative charge state to positive charge state, which leads to the conversion from cationic selectivity to anionic selectivity. We continue to study the charge reversal process of polyvalent cations on the surface of mono-conical nano-channels. It is found that the surface charge inversion is mainly due to the adsorption of polyvalent cations on the pore wall and is affected by the concentration of electrolyte solution. The data show that the concentration of charge inversion in trivalent ion solution is lower than that in divalent ion solution, but no surface charge inversion is observed in monovalent ion solution.
【學位授予單位】：中國科學院大學(中國科學院近代物理研究所)
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TB383.1

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本文編號：2180506