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11:42
Fabrication of Gate-tunable Graphene Devices for Scanning Tunneling Microscopy Studies with Coulomb Impurities
Published on: July 24, 2015
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Heterogeneous sub-continuum ionic transport in statistically isolated graphene nanopores
Tarun Jain1, Benjamin C Rasera1, Ricardo Jose S Guerrero1
1Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Nature Nanotechnology
|October 6, 2015
Summary
Graphene nanopores exhibit unique ion transport behaviors due to their small size. These findings advance understanding of sub-continuum transport for separations and sensing applications.
Area of Science:
- Materials Science
- Nanotechnology
- Physical Chemistry
Background:
- Two-dimensional materials like graphene offer ultrathin membranes with atomically defined nanopores.
- These nanopores, smaller than 2 nm, operate in a novel transport regime due to ionic dehydration and electrokinetic effects.
- Understanding sub-continuum ionic transport in such small pores is experimentally limited.
Purpose of the Study:
- To experimentally characterize and understand ionic transport in sub-2 nm graphene nanopores.
- To investigate the diverse transport behaviors and selectivity profiles of these nanopores.
- To model the observed phenomena using a modified Nernst-Planck equation.
Main Methods:
- Fabrication of isolated sub-2 nm pores in graphene membranes.
- Conducting current-voltage (I-V) measurements to analyze ion transport.
- Utilizing a modified Nernst-Planck model incorporating hydration and electrostatic effects for quantitative matching.
Main Results:
- Graphene nanopores exhibit diverse transport behaviors, including linear, voltage-activated, and rectified I-V characteristics.
- Nanopore conductance spans three orders of magnitude, with varying cation selectivity.
- Stochastic switching, indicative of dissociable groups, was observed in some pores.
- The modified Nernst-Planck model accurately reproduced the experimental observations.
Conclusions:
- Sub-2 nm graphene nanopores display complex transport governed by ion dehydration and electrostatic interactions.
- These findings reveal a novel transport regime crucial for developing advanced separation and sensing technologies.
- The study provides a quantitative model for predicting ion transport in nanoscale pores.
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