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Title: History-dependent ion transport through conical nanopipettes and the implications in energy conversion dynamics at nanoscale interfaces

Abstract

The dynamics of ion transport at nanostructured substrate–solution interfaces play vital roles in high-density energy conversion, stochastic chemical sensing and biosensing, membrane separation, nanofluidics and fundamental nanoelectrochemistry. Advancements in these applications require a fundamental understanding of ion transport at nanoscale interfaces. The understanding of the dynamic or transient transport, and the key physical process involved, is limited, which contrasts sharply with widely studied steady-state ion transport features at atomic and nanometer scale interfaces. Here we report striking time-dependent ion transport characteristics at nanoscale interfaces in current–potential (I–V) measurements and theoretical analyses. First, a unique non-zero I–V cross-point and pinched I–V curves are established as signatures to characterize the dynamics of ion transport through individual conical nanopipettes. Moreoever, ion transport against a concentration gradient is regulated by applied and surface electrical fields. The concept of ion pumping or separation is demonstrated via the selective ion transport against concentration gradients through individual nanopipettes. Third, this dynamic ion transport process under a predefined salinity gradient is discussed in the context of nanoscale energy conversion in supercapacitor type charging–discharging, as well as chemical and electrical energy conversion. Our analysis of the emerging current–potential features establishes the urgently needed physical foundation for energy conversion employingmore » ordered nanostructures. The elucidated mechanism and established methodology can be generalized into broadly-defined nanoporous materials and devices for improved energy, separation and sensing applications.« less

Authors:
 [1];  [1];  [1];  [1];  [1];  [1]
  1. Georgia State Univ., Atlanta, GA (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF)
OSTI Identifier:
1265884
Grant/Contract Number:
AC05-00OR22725; 1059022
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Chemical Science
Additional Journal Information:
Journal Volume: 6; Journal Issue: 1; Journal ID: ISSN 2041-6520
Publisher:
Royal Society of Chemistry
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Li, Yan, Wang, Dengchao, Kvetny, Maksim M., Brown, Warren, Liu, Juan, and Wang, Gangli. History-dependent ion transport through conical nanopipettes and the implications in energy conversion dynamics at nanoscale interfaces. United States: N. p., 2014. Web. doi:10.1039/C4SC02195A.
Li, Yan, Wang, Dengchao, Kvetny, Maksim M., Brown, Warren, Liu, Juan, & Wang, Gangli. History-dependent ion transport through conical nanopipettes and the implications in energy conversion dynamics at nanoscale interfaces. United States. doi:10.1039/C4SC02195A.
Li, Yan, Wang, Dengchao, Kvetny, Maksim M., Brown, Warren, Liu, Juan, and Wang, Gangli. Wed . "History-dependent ion transport through conical nanopipettes and the implications in energy conversion dynamics at nanoscale interfaces". United States. doi:10.1039/C4SC02195A. https://www.osti.gov/servlets/purl/1265884.
@article{osti_1265884,
title = {History-dependent ion transport through conical nanopipettes and the implications in energy conversion dynamics at nanoscale interfaces},
author = {Li, Yan and Wang, Dengchao and Kvetny, Maksim M. and Brown, Warren and Liu, Juan and Wang, Gangli},
abstractNote = {The dynamics of ion transport at nanostructured substrate–solution interfaces play vital roles in high-density energy conversion, stochastic chemical sensing and biosensing, membrane separation, nanofluidics and fundamental nanoelectrochemistry. Advancements in these applications require a fundamental understanding of ion transport at nanoscale interfaces. The understanding of the dynamic or transient transport, and the key physical process involved, is limited, which contrasts sharply with widely studied steady-state ion transport features at atomic and nanometer scale interfaces. Here we report striking time-dependent ion transport characteristics at nanoscale interfaces in current–potential (I–V) measurements and theoretical analyses. First, a unique non-zero I–V cross-point and pinched I–V curves are established as signatures to characterize the dynamics of ion transport through individual conical nanopipettes. Moreoever, ion transport against a concentration gradient is regulated by applied and surface electrical fields. The concept of ion pumping or separation is demonstrated via the selective ion transport against concentration gradients through individual nanopipettes. Third, this dynamic ion transport process under a predefined salinity gradient is discussed in the context of nanoscale energy conversion in supercapacitor type charging–discharging, as well as chemical and electrical energy conversion. Our analysis of the emerging current–potential features establishes the urgently needed physical foundation for energy conversion employing ordered nanostructures. The elucidated mechanism and established methodology can be generalized into broadly-defined nanoporous materials and devices for improved energy, separation and sensing applications.},
doi = {10.1039/C4SC02195A},
journal = {Chemical Science},
number = 1,
volume = 6,
place = {United States},
year = {Wed Aug 20 00:00:00 EDT 2014},
month = {Wed Aug 20 00:00:00 EDT 2014}
}

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Cited by: 8works
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  • We report striking time-dependent ion transport characteristics at nanoscale interfaces in current–potential (I–V) measurements and theoretical analyses.
  • We report striking time-dependent ion transport characteristics at nanoscale interfaces in current–potential (I–V) measurements and theoretical analyses.
  • As device miniaturization approaches nanoscale dimensions, interfaces begin to dominate electrical properties. Here the system archetype Au/SrTiO{sub 3} is used to examine the origin of size dependent transport properties along metal-oxide interfaces. We demonstrate that a transition between two classes of size dependent electronic transport mechanisms exists, defined by a critical size ε. At sizes larger than ε an edge-related tunneling effect proportional to 1/D (the height of the supported Au nanoparticle) is observed; interfaces with sizes smaller than ε exhibit random fluctuations in current. The ability to distinguish between these mechanisms is important to future developments in nanoscale devicemore » design.« less
  • Electrostatic interactions of mobile charges in solution with the fixed surface charges are known to strongly affect stochastic sensing and electrochemical energy conversion processes at nanodevices or devices with nanostructured interfaces. The key parameter to describe this interaction, surface charge density (SCD), is not directly accessible at nanometer scale and often extrapolated from ensemble values. In this report, the steady-state current–voltage (i–V) curves measured using single conical glass nanopores in different electrolyte solutions are fitted by solving Poisson and Nernst–Planck equations through finite element approach. Both high and low conductivity state currents of the rectified i–V curve are quantitatively fittedmore » in simulation at less than 5% error. The overestimation of low conductivity state current using existing models is overcome by the introduction of an exponential SCD distribution inside the conical nanopore. A maximum SCD value at the pore orifice is determined from the fitting of the high conductivity state current, while the distribution length of the exponential SCD gradient is determined by fitting the low conductivity state current. Quantitative fitting of the rectified i–V responses and the efficacy of the proposed model are further validated by the comparison of electrolytes with different types of cations (K + and Li +). In conclusion, the gradient distribution of surface charges is proposed to be dependent on the local electric field distribution inside the conical nanopore.« less