论文标题
超越权衡：离子运输和当前选择性的动态选择性
Beyond the Tradeoff: Dynamic Selectivity in Ionic Transport and Current Selectivity
论文作者
论文摘要
传统上，纳米孔和纳米多孔膜中的离子 - 选择性被认为是Debye重叠的结果，在该膜上，Debye筛选长度与纳米孔长度沿某个位置的纳米孔半径相当。该标准对离子选择性纳米孔的大小设定了一个显着限制，因为对于典型的离子浓度的debye长度为1-10 nm。但是，我们在这里提出的分析结果表明，表面电导在离子传输中产生动力学选择性，并且这种选择性由所谓的dukhin而不是Debye控制，而不是Debye重叠。 DUKHIN长度定义为表面与散装电导的比率，达到了数百纳米的值，用于典型的表面电荷密度和离子浓度，这表明具有设计大纳米孔（10-100 nm）的可能性，高导电膜，具有显着的离子离子电气。这种膜对渗透能量转化和分离技术的效率可能具有显着意义。此外，我们证明了这种动态选择性的机制最终导致离子电流的纠正，合理化了先前的研究，表明Debye重叠并不是纳米孔中整流行为的必要条件。
Traditionally, ion-selectivity in nanopores and nanoporous membranes is understood to be a consequence of Debye overlap, in which the Debye screening length is comparable to the nanopore radius somewhere along the length of the nanopore(s). This criterion sets a significant limitation on the size of ion-selective nanopores, as the Debye length is on the order of 1 - 10 nm for typical ionic concentrations. However, the analytical results we present here demonstrate that surface conductance generates a dynamical selectivity in ion transport, and this selectivity is controlled by so-called Dukhin, rather than Debye, overlap. The Dukhin length, defined as the ratio of surface to bulk conductance, reaches values of hundreds of nanometers for typical surface charge densities and ionic concentrations, suggesting the possibility of designing large-nanopore (10 - 100 nm), high-conductance membranes exhibiting significant ion-selectivity. Such membranes would have potentially dramatic implications for the efficiency of osmotic energy conversion and separation techniques. Furthermore, we demonstrate that this mechanism of dynamic selectivity leads ultimately to the rectification of ionic current, rationalizing previous studies showing that Debye overlap is not a necessary condition for the occurrence of rectifying behavior in nanopores.
