Recent theoretical research on the fundamentals of statistical mechanics has led to a counterintuitive finding [2-5]: with a locally nonchaotic energy barrier, a macroscopic many-particle system may reach an intrinsic-nonequilibrium steady state without any external driving force, incompatible with the conventional statements of the second law of thermodynamics. In the present investigation, we experimentally demonstrate the concept of intrinsic nonequilibrium by replacing the weak gravitational force in the "toy model" with a strong Coulomb force. The tests are performed on a set of nanoporous carbon electrodes immersed in aqueous cesium pivalate solutions. The key characteristic is that the effective nanopore size is only slightly larger than the effective ion size but less than twice the ion size, so that the motion of the confined ions is quasi-one-dimensional and relatively nonchaotic. At first glance, the supercapacitive cells exhibit "normal" charge curves. However, the steady-state distribution of the large ions in the charged small nanopores (measured by the charge efficiency) inherently differs from equilibrium by nearly one order of magnitude, thereby breaking the boundaries of the second law of thermodynamics and potentially opening the possibility of producing useful work by absorbing heat from a single thermal reservoir with no other effect. Such an unusual phenomenon is compatible with the basic principle of maximum entropy and does not challenge the second law within its established domain of application (fully chaotic systems); instead, it extends our understanding of thermodynamics beyond the traditional framework.
We employ a field-theoretical variational approach to study the behavior of ionic solutions in the grand canonical ensemble. To describe properly the hardcore interactions between ions, we use a cutoff in Fourier space for the electrostatic contribution of the grand potential and the Carnahan-Starling equation of state with a modified chemical potential for the pressure one. We first calibrate our method by comparing its predictions at room temperature with Monte Carlo results for excess chemical potential and energy. We then validate our approach in the bulk phase by describing the classical …
Using theory and simulations, we carried out a first systematic characterization of DNA unzipping via nanopore translocation. Starting from partially unzipped states, we found three dynamical regimes depending on the applied force, f: (i) heterogeneous DNA retraction and rezipping (f < 17pN), (ii) normal (17pN < f < 60pN) and (iii) anomalous (f > 60pN) drift-diffusive behavior. We show that the normal drift-diffusion regime can be effectively modelled as a one-dimensional stochastic process in a tilted periodic potential. We use the theory of stochastic processes to recover the potential from …
Reproducing the exquisite ion selectivity displayed by biological ion channels in artificial nanopore systems has proven to be one of the most challenging tasks undertaken by the nanopore community, yet a successful achievement of this goal offers immense technological potential. Here we show a strategy to design solid-state nanopores that selectively transport potassium ions and show negligible conductance for sodium ions. The nanopores contain walls decorated with 4'-aminobenzo-18-crown-6 ether and ssDNA molecules located at one pore entrance. The ionic selectivity stems from facilitated tra…
Scaling of the behavior of a nanodevice means that the device function (selectivity, in this work) is a unique function of a scaling parameter that is an appropriate combination of the device parameters. Although nanopores facilitate the transport of ions through a membrane of finite length if the pore is long compared to the pore radius, we deal with an important limiting case, the infinitely long nanopore (nanotube). While in our previous study (Sarkadi et al., J. Chem. Phys. 154 (2021) 154704.) we showed that the Dukhin number is an appropriate scaling parameter in the nanotube limit for 1:…
We investigate a model nanopore sensor that is able to detect analyte ions that are present in the electrolyte solution in very small concentrations. The nanopore selectively binds the analyte ions with which the local concentrations of the ions of the background electrolyte (KCl), and, thus, the ionic current flowing through the pore is changed. Analyte concentration can be determined from calibration curves. In our previous study (Mádai et al. J. Chem. Phys., 147(24):244702, 2017.), we proposed a symmetric model (surface charge is negative all along the pore). The mechanism of sensing was a …
The recent measurement of a very low dielectric constant, $ε$, of water confined in nanometric slit pores leads us to reconsider the physical basis of ion partitioning into nanopores. For confined ions in chemical equilibrium with a bulk of dielectric constant $ε_b>ε$, three physical mechanisms, at the origin of ion exclusion in nanopores, are expected to be modified due to this dielectric mismatch: dielectric exclusion at the water-pore interface (with membrane dielectric constant, $ε_m<ε$), the solvation energy related to the difference in Debye-Hückel screening parameters in the pore, $κ$, …
Bipolar nanopores have powerful rectification properties due to the asymmetry in the charge pattern on the wall of the nanopore. In particular, bipolar nanopores have positive and negative surface charges along the pore axis. Rectification is strong if the radius of the nanopore is small compared to the screening length of the electrolyte so that both cations and anions have depletion zones in the respective regions. The depths of these depletion zones is sensitive to sign of the external voltage. In this work, we are interested in the effect of the presence of strong ionic correlations (both …
Ion size effects at ionic exclusion from dielectric interfaces and slit nanopores
先前开发的场论模型[R. D. Coalson等人，J.Chem.Phys.102，4584（1995）]，其在相同的基础上处理核碰撞和库仑相互作用，以理解离子尺寸对中性和带电粒子在平面界面处的分配的影响以及狭缝纳米孔的离子选择性。我们引入了一个变分方案，可以超越平均场（MF）制度，并以一致的方式耦合孔改性的核心相互作用，空间位阻效应，静电溶剂化和图像电荷力，和表面电荷诱导的静电势。我们表明，在稀释的限制，MF和变分理论符合MC模拟结果，在最近的RPA方法相比。研究了带电汤川粒子在中性介质界面（如空气-水或蛋白质-水界面）的分配。它示出，作为一个结果的核心碰撞之间的竞争，推动离子的表面，排斥溶剂化和图像的力量，排除他们从接口，浓度峰值的有限大小的离子集在接近的电介质界面。我们还表征了中性狭缝纳米孔的离子选择性的离子尺寸所发挥的作用。我们发现，复杂的相互作用之间的静电力，排除体积效应引起的核心碰撞和空间效应导致一个意想不到的逆转，在不同孔径的孔的离子选择性：而大孔表现出更高的电导率为大离子，窄孔排除大离子比小的更有效。
The alteration of the dielectric membrane properties by membrane engineering techniques such as carbon nanotube (CNT) coating opens the way to novel molecular transport strategies for biosensing purposes. In this article, we predict a macromolecular transport mechanism enabling the dielectric manipulation of the polymer translocation dynamics in dielectric membrane pores confining mixed electrolytes. In the giant permittivity regime of these engineered membranes governed by attractive polarization forces, multivalent ions adsorbed by the membrane nanopore trigger a monovalent ion separation an…
We model and simulate a nanopore sensor that selectively binds analyte ions. This binding leads to the modulation of the local concentrations of the ions of the background electrolyte (KCl), and, thus, to the modulation of the ionic current flowing through the pore. The nanopore's wall carries a bipolar charge pattern with a larger positive buffer region determining the anions as the main charge carriers and the smaller negative binding region containing binding sites. This charge pattern proved to be an appropriate one as shown by a previous comparative study of varying charge patterns (Mádai…
We present coarse-grained simulation results for enhanced ion diffusion in a charged nanopore grafted with ionomer sidechains. The pore surface is hydrophobic and its diameter is varied from 2.0 nm to 3.7 nm. The sidechains have from 2 to 16 monomers (united atom units) and contain sulfonate terminal groups. Our simulation results indicate a strong dependence of the ion diffusion along the pore axis on the pore parameters. In the case of short sidechains and large pores the ions mostly occupy the pore wall area, where their distribution is strongly disturbed by their host sulfonates. In the ca…
When channels were scaled down to the size of hydrated ions, ionic Coulomb blockade was discovered. However, the experimental CB phenomenon was rarely reported since Feng et.al., discovered in MoS2 nanopore. By using latent-track membranes with diameter of 0.6 nm, we found the channels are nearly non-conductive in small voltage due to the blockade of cations bound at surface, however turns to be conductive as rising of voltage due to releasing of bound ions, which differs from the mechanisms in MoS2 nanopore. By Kramers' escape framework, we rationalized an analytical equation to fit experimen…
In this paper we report the theory describing the electro-osmotic flow in charged nanopores with constant radius and charge density driven by alternating current. We solve the ion and solution transport in unsteady conditions as described by the Navier-Stokes and Nernst-Planck equations considering the electrical potential inside the charged nanopore uniform in the radial direction (Uniform Potential model approximation). We derive the transport equation system in the case in which the pore is connected to two boundary diffusion layers and the cations and anions have different diffusion coeffi…
Donnan equilibrium in charged slit-pores from a hybrid nonequilibrium Molecular Dynamics / Monte Carlo method with ions and solvent exchange
Korea Institute of Energy Technology (KENTECH)（韩国能源技术研究院）；Sorbonne Université（索邦大学）；CNRS（法国国家科学研究中心）；Physico-chimie des Électrolytes et Nanosystemès Interfaciaux, PHENIX（界面电解质与纳米系统物理化学实验室）；Réseau sur le Stockage Electrochimique de l’Energie (RS2E), FR CNRS 3459（电化学储能网络）
