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Title: Voltage-Rectified Current and Fluid Flow in Conical Nanopores

Authors:
 [1];  [1];  [1];  [1];  [2];  [2];  [1]
  1. Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
  2. Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, United States
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Nanostructures for Electrical Energy Storage (NEES)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1388834
DOE Contract Number:
SC0001160
Resource Type:
Journal Article
Resource Relation:
Journal Name: Accounts of Chemical Research; Journal Volume: 49; Journal Issue: 11; Related Information: NEES partners with University of Maryland (lead); University of California, Irvine; University of Florida; Los Alamos National Laboratory; Sandia National Laboratories; Yale University
Country of Publication:
United States
Language:
English
Subject:
bio-inspired, energy storage (including batteries and capacitors), defects, charge transport, synthesis (novel materials), synthesis (self-assembly), synthesis (scalable processing)

Citation Formats

Lan, Wen-Jie, Edwards, Martin A., Luo, Long, Perera, Rukshan T., Wu, Xiaojian, Martin, Charles R., and White, Henry S. Voltage-Rectified Current and Fluid Flow in Conical Nanopores. United States: N. p., 2016. Web. doi:10.1021/acs.accounts.6b00395.
Lan, Wen-Jie, Edwards, Martin A., Luo, Long, Perera, Rukshan T., Wu, Xiaojian, Martin, Charles R., & White, Henry S. Voltage-Rectified Current and Fluid Flow in Conical Nanopores. United States. doi:10.1021/acs.accounts.6b00395.
Lan, Wen-Jie, Edwards, Martin A., Luo, Long, Perera, Rukshan T., Wu, Xiaojian, Martin, Charles R., and White, Henry S. Fri . "Voltage-Rectified Current and Fluid Flow in Conical Nanopores". United States. doi:10.1021/acs.accounts.6b00395.
@article{osti_1388834,
title = {Voltage-Rectified Current and Fluid Flow in Conical Nanopores},
author = {Lan, Wen-Jie and Edwards, Martin A. and Luo, Long and Perera, Rukshan T. and Wu, Xiaojian and Martin, Charles R. and White, Henry S.},
abstractNote = {},
doi = {10.1021/acs.accounts.6b00395},
journal = {Accounts of Chemical Research},
number = 11,
volume = 49,
place = {United States},
year = {Fri Sep 30 00:00:00 EDT 2016},
month = {Fri Sep 30 00:00:00 EDT 2016}
}
  • Single conically shaped nanopores produce stable ion current fluctuations when in contact with weakly soluble salts, such as calcium hydrogen phosphate (CaHPO{sub 4}) and cobalt hydrogen phosphate (CoHPO{sub 4}). The pore spontaneously switches between high and low conductance states, called open and closed states, respectively. Pore opening and closing are linked to the dynamic formation of the calcium and cobalt precipitates at the small opening of the pore. The probabilities of pore opening and closing are voltage-dependent, and this characteristic of ion current signal is known for biological voltage-gated channels. We show that new types of ion current fluctuations aremore » obtained in conditions at which precipitates of CaHPO{sub 4} and CoHPO{sub 4} can form in the pore at the same time.« less
  • Current rectification is well known in ion transport through nanoscale pores and channel devices. The measured current is affected by both the geometry and fixed interfacial charges of the nanodevices. In this article, an interesting trend is observed in steady-state current–potential measurements using single conical nanopores. A threshold low-conductivity state is observed upon the dilution of electrolyte concentration. Correspondingly, the normalized current at positive bias potentials drastically increases and contributes to different degrees of rectification. This novel trend at opposite bias polarities is employed to differentiate the ion flux affected by the fixed charges at the substrate–solution interface (surface effect),more » with respect to the constant asymmetric geometry (volume effect). The surface charge density (SCD) of individual nanopores, an important physical parameter that is challenging to measure experimentally and is known to vary from one nanopore to another, is directly quantified by solving Poisson and Nernst–Planck equations in the simulation of the experimental results. The flux distribution inside the nanopore and the SCD of individual nanopores are reported. The respective diffusion and migration translocations are found to vary at different positions inside the nanopore. This knowledge is believed to be important for resistive pulse sensing applications because the detection signal is determined by the perturbation of the ion current by the analytes.« less
  • Current rectification is well-known in ion transport through nanoscale pores and channel devices. The measured current is affected by both the geometry and fixed interfacial charges of the nanodevices. In this paper, an interesting trend is observed in steady-state current-potential measurements using single conical nanopores. A threshold low conductivity state is observed upon the dilution of electrolyte concentration. Correspondingly, the normalized current at positive bias potentials drastically increases and contributes to different degree of rectification. The novel opposite trend at opposite bias polarities is employed to differentiate the ion flux affected by the fixed charges at the substrate-solution interface (surfacemore » effect), with respect to the constant asymmetric geometry (volume effect). The surface charge density (SCD) of individual nanopores, an important physical parameter that is challenging to measure experimentally and is known to vary from one nanopore to another, are directly quantified by solving Poisson and Nernst-Planck equations in the simulation of the experimental results. Flux distribution inside the nanopore and SCD of individual nanopores are reported. The respective diffusion and migration translocations are found to vary at different positions inside the nanopore. The knowledge is believed important for resistive pulse sensing applications, as the detection signal is determined by the perturbation of ion current by the analytes.« less
  • Here, we studied the transport of room-temperature ionic liquids (RTILs) through charged conical nanopores using a Landau-Ginzburg-type continuum model that takes steric effect and strong ion-ion correlations into account. When the surface charge is uniform on the pore wall, weak current rectification is observed. When the charge density near the pore base is removed, the ionic current is greatly suppressed under negative bias voltage while nearly unchanged under positive bias voltage, thereby leading to enhanced current rectification. These predictions agree qualitatively with prior experimental observations, and we elucidated them by analyzing the different components of the ionic current and themore » structural changes of electrical double layers (EDLs) at the pore tip under different bias voltages and surface charge patterns. These analyses reveal that the different modifications of the EDL structure near the pore tip by the positive and negative bias voltages cause the current rectification and the observed dependence on the distribution of surface charge on the pore wall. The fact that the current rectification phenomena are captured qualitatively by the simple model originally developed for describing EDLs at equilibrium conditions suggests that this model may be promising for understanding the ionic transport under nonequilibrium conditions when the EDL structure is strongly perturbed by external fields.« less