【摘要】：單錐形納米孔道由于具有對(duì)稱(chēng)性破缺和表面電荷特性而表現(xiàn)出整流效應(yīng),因此在離子分離、電能供應(yīng)、化學(xué)閥等領(lǐng)域具有重要的潛在應(yīng)用價(jià)值。深入研究納米孔道中的電學(xué)特性及納米孔道修飾方法,對(duì)于理解納米尺度下的離子輸運(yùn)特性和改進(jìn)錐形納米孔道應(yīng)用性能具有重要的意義。本文基于蘭州交叉學(xué)科重離子微束裝置的單離子輻照技術(shù),用單個(gè)離子輻照PET薄膜樣品,通過(guò)化學(xué)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(cè)量了多種電解質(zhì)溶液在單錐形納米孔道中的離子輸運(yùn)特性。研究發(fā)現(xiàn),在KCl、NaCl、LiCl、MgCl_2、CaCl_2五種不同的溶液中均可以觀測(cè)到單錐形納米孔道的整流效應(yīng),并且整流系數(shù)都隨溶液濃度增加呈現(xiàn)先增大后減小的趨勢(shì);相比于一價(jià)電解質(zhì)溶液,二價(jià)電解質(zhì)溶液中整流系數(shù)在較低濃度下就能達(dá)到最大值。對(duì)此我們提出了單錐形納米孔道內(nèi)的離子輸運(yùn)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(nèi)的勢(shì)阱的變化,成功解釋了觀察到的實(shí)驗(yàn)現(xiàn)象。為了對(duì)整流效應(yīng)有更深入的理解,我們進(jìn)一步對(duì)單錐形納米孔道的離子選擇性進(jìn)行了研究。我們?cè)O(shè)計(jì)實(shí)驗(yàn)實(shí)現(xiàn)了單錐形納米孔道內(nèi)離子的單向輸運(yùn)測(cè)試,通過(guò)陰陽(yáng)離子電流大小可以確定單錐形納米孔道的陰陽(yáng)離子選擇性。我們發(fā)現(xiàn)PET單錐形納米孔道在多價(jià)陽(yáng)離子溶液中浸泡會(huì)使其表面由負(fù)電荷態(tài)轉(zhuǎn)變?yōu)檎姾蓱B(tài),進(jìn)而導(dǎo)致其由陽(yáng)離子選擇性轉(zhuǎn)變?yōu)殛庪x子選擇性。我們繼續(xù)研究了多價(jià)陽(yáng)離子使單錐形納米孔道表面電荷反轉(zhuǎn)的過(guò)程,發(fā)現(xiàn)其表面電荷反轉(zhuǎn)主要是由于多價(jià)陽(yáng)離子在孔壁上的吸附,并且受到電解質(zhì)溶液濃度的影響。數(shù)據(jù)顯示,三價(jià)離子溶液中的電荷反轉(zhuǎn)濃度小于二價(jià)離子,而一價(jià)離子溶液中未觀測(cè)到表面電荷反轉(zhuǎn)。
[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(xué)位授予單位】：中國(guó)科學(xué)院大學(xué)(中國(guó)科學(xué)院近代物理研究所)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：TB383.1

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本文編號(hào)：2180506