Bulletin of the American Physical Society
APS March Meeting 2021
Volume 66, Number 1
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session M25: Behavior of Liquids Confined on the Nanometer Scale IIFocus Live
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Sponsoring Units: DCP Chair: Mark Reed, Yale University |
Wednesday, March 17, 2021 11:30AM - 11:42AM Live |
M25.00001: Pressure-Induced Enlargement and Ionic Current Rectification in Symmetric Nanopores Sebastian James Davis, Michal Macha, Andrey Chernev, David M Huang, Aleksandra Radenovic, Sanjin Marion
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Wednesday, March 17, 2021 11:42AM - 11:54AM Live |
M25.00002: Ion Solvation and Transport in Narrow Carbon Nanotubes: Effects of Polarizability, Cation-p Interaction and Confinement Fikret Aydin, Alireza Moradzadeh, Camille Bilodeau, Edmond Lau, Eric R Schwegler, N. R. Aluru, Tuan Anh Pham Understanding ion solvation and transport under nanoscale confinement is important for a wide range of emerging technologies such as energy storage and water desalination. While molecular dynamics simulations have been commonly used to study the behaviors of ions under confinements, there are still considerable deviations between the simulation results depending on the specific treatment of intermolecular interactions. In this work, we present a systematic investigation of structure and transport properties of aqueous salt solutions (KCl and LiCl) confined in narrow carbon nanotubes by using a combination of first-principles and classical molecular dynamics simulations with and without the inclusion of polarization effects. The inclusion of both polarization and cation-p interactions are found to be essential for the description of ion solvation under confinement. In addition, our simulations point to a strong correlation between ion dehydration and diffusion, particularly for KCl, which shows the important role of cation-p interactions in the transport properties of ions in these narrow CNTs. Thus, our study shows that the ion solvation and transport properties are strongly influenced by the complex interplay between nanoconfinement and specific intermolecular interactions. |
Wednesday, March 17, 2021 11:54AM - 12:06PM Live |
M25.00003: Direct observation of water-mediated single-proton transport between hBN surface defects Jean Comtet, Benoit Grosjean, Evgenii glushkov, Ahmet Avsar, Kenji Watanabe, Takashi Taniguchi, Rodolphe Vuilleumier, Marie-Laure Bocquet, Aleksandra Radenovic Aqueous proton transport at interfaces is ubiquitous and crucial for a number of fields, ranging from cellular transport and signalling, to catalysis and membrane science. However, due to their light mass, small size and high chemical reactivity, uncovering the surface transport of single protons at room temperature and in an aqueous environment has so far remained out-of-reach of conventional atomic-scale surface science techniques, such as scanning tunnelling microscopy. Here, we use single-molecule localization microscopy to resolve optically the transport of individual excess protons at the interface of hexagonal boron nitride crystals and aqueous solutions at room temperature. Single excess proton trajectories are revealed by the successive protonation and activation of optically active defects at the surface of the crystal. Our observations demonstrate, at the single-molecule scale, that the solid/water interface provides a preferential pathway for lateral proton transport, with broad implications for molecular charge transport at liquid interfaces. |
Wednesday, March 17, 2021 12:06PM - 12:18PM Live |
M25.00004: Mechanosensitive conductance of single-digit carbon nanotubes Alice Marcotte, Timothée Mouterde, Antoine Niguès, Alessandro Siria, Lydéric Bocquet Despite the recent advances in the conception of artificial devices with nanometre scale confinements, these are still far from the advanced functionalities existing in biological systems, such as ionic pumping, or electrically and mechanically activated transport. However the unusual properties of carbon nanotubes (CNT) in term of water and ion transport open new possibilities for the development of advanced iontronic functions. |
Wednesday, March 17, 2021 12:18PM - 12:30PM Live |
M25.00005: Non-Reciprocal Interactions between Ions Near a Graphene Surface Felipe Jimenez, Katherine Harmon, Trung Nguyen, Paul Fenter, Monica Olvera De La Cruz Ions in aqueous media near surfaces are ubiquitous in nature and technology, thereby quantifying electrostatic interactions near interfaces is of prime importance. Here we investigate the effective interaction between two oppositely charged ions in different positions in water confined between two graphene surfaces. We found that the attraction between oppositely charged ions physisorbed at the water/graphene interface is enhanced in the direction perpendicular to the interface and the attraction is further amplified by enhancing the confinement. This interaction becomes repulsive when one ion is intercalated into the graphene layers and the other is physisorbed at the interface. In the in-plane direction the interaction is almost unaffected while in the perpendicular direction the interaction energy changes by about 5 kBT just by interchanging the ion’s position. Due to the symmetry breaking, the interfacial electrostatic interactions are referred to as nonreciprocal. Our results imply that electrostatic interactions near interfaces cannot be described using an inhomogeneous dielectric permittivity obtained via the water structure. |
Wednesday, March 17, 2021 12:30PM - 12:42PM Live |
M25.00006: Nanoconfinement of Water-in-Salt Electrolytes in Nanometer-wide Boron-Nitride Nanotube for Potential Application in Aqueous Li-ion Batteries. Bhargav Sai Chava, Yanbin Wang, VISHAL SANKAR SIVASANKAR, Siddhartha Das Aqueous Li-ion battery performance has been recently identified to be enhanced by using highly concentrated water-in-salt electrolyte (WISE) systems due to the formation of solid electrolyte interphase (SEI) at the negative electrode. The localization of the cation-anion pair near the negative electrode in the absence of free water plays an important role in SEI formation. In this study, atomistic simulations are conducted to show that a LiTFSI aqueous electrolyte solution of a much lower concentration is enough to ensure such water-free TFSI- anion localization at the negative electrode surface. Such a scenario is made possible by confining the LiTFSI electrolyte solution in a 1-nm-diameter boron nitride nanotube (BNNT). Our findings indicate that the interplay of the greater affinity of the TFSI- ion to enter the empty 1nm-wide BNNT before other electrolyte molecules and the nano-confinement, which results in the molecular ordering of the TFSI- ions and water molecules, allow such water-free localization of the TFSI- ion at the negative electrode. |
Wednesday, March 17, 2021 12:42PM - 1:18PM Live |
M25.00007: Single nanopores as a model system to probe interfaces in aqueous and organic media Invited Speaker: Zuzanna Siwy Nanopores with tunable geometry and electrochemical properties of the pore walls serve as a template to understand ionic and molecular transport at extreme confinement. Due to nanoconfinement, nanopores can exhibit ionic selectivity, i.e. the ability to transport only one type of ions, nonlinear current-voltage characteristics, and ion current switching behavior, among others. In the talk, I will present how ionic current through nanopores can be used to uncover properties of solid/liquid interfaces in aqueous and non-aqueous media. In the research we used single nanopores with opening as small as a few nanometers prepared in polymer as well as silicon nitride films. I will show how effective surface charge of the pore walls can be switched when the pore is in contact with multivalent ions and even salt solutions in some organic solvents. Finally, benefits of connecting nanopores in ionic circuits will be shown as well together with a design of ionic amplifiers. |
Wednesday, March 17, 2021 1:18PM - 1:30PM Live |
M25.00008: Understanding the cation selectivity and confinement in carbon-based nanopores from hybrid first-principles quantum-continuum simulation Cheng Zhan, Fikret Aydin, Eric R Schwegler, Aleksandr Noy, Tuan Anh Pham Understanding the cation selectivity under confinement in carbon nanopore is essential in environmental and energy technologies, such as water purification and capacitive energy storage. In this work, we investigate cation selectivity and confinement effects by using hybrid quantum-continuum simulation that provides a more realistic description of the ion-pore interaction than conventional classical force fields. By computing the change in the free energy of alkaline metal cations (Li+, Na+, K+, Cs+) during the intercalation process, we show that large cations are more preferable to enter the pore, but their relative selectivity can be manipulated by pore size and geometry. In addition to selectivity, the interfacial charge transfer, solvent number change and hydration structure of cations were also found to be significantly influenced by the pore size and geometry, indicating the complex interplay and competition between ion hydration and ion-pore interaction under confinement. Based on these results, we discuss possible application of specific type of nanopores for the separation of alkaline metal cations. |
Wednesday, March 17, 2021 1:30PM - 1:42PM Live |
M25.00009: Interfacial Layering in the Electric Double Layer of Concentrated Electrolytes and Ionic Liquids Pedro De Souza, Zachary Goodwin, Michael P McEldrew, Alexei Kornyshev, Martin Bazant Ionic liquids and concentrated electrolytes form discrete layers of ions at charged surfaces due to strong steric and electrostatic interactions. Here, we present a theory that captures the interplay between overcrowding--the formation of dense layers of counterions at high surface charge densities-- and overscreening-- alternating layers of charge at low surface charge densities. Mathematically, the key to describing the interfacial concentration profile is to represent the electrostatic and excess free energy functional in terms of weighted densities. The concentration and differential capacitance predictions of the theory agree with molecular dynamics simulations of a representative ionic liquid. The theory outputs a simple formula for the length of decaying oscillations which become more long range as the ionic concentration increases. Finally, leveraging the theory, we demonstrate how the structure of an ionic liquid or concentrated electrolyte may change in confinement, and how overscreening and overcrowding phenomena can affect surface force measurements of these confined systems. |
Wednesday, March 17, 2021 1:42PM - 2:18PM Live |
M25.00010: Ion transport in sub-1-nm carbon nanotube porins. Invited Speaker: Aleksandr Noy Controlling water an ion transport on a molecular scale is important for applications ranging from water treatment, to membrane separations, to bioelectronic interface design. Living systems are adept at moving ions and small molecules across biological membranes using protein pores that rely on nanoscale confinement to achieve efficient and exquisitely selective transport. I will show that carbon nanotube porins—pore channels formed by short carbon nanotubes assembled in a lipid membrane—can exploit similar physical principles to transport ions and achieve differential ion selectivity. I will discuss the role of molecular confinement and ion interactions with the nanopore walls and show how these phenomena enhance water and ion transport efficiency and influence the mechanisms of ion selectivity and electroosmotic coupling in these pores. Overall, carbon nanotube porins represent a versatile biomimetic membrane pores that are ideal for fundamental nanofluidics studies and for building the next generation of separation technologies. |
Wednesday, March 17, 2021 2:18PM - 2:30PM On Demand |
M25.00011: Chemical Potential-Driven Ion Transport through Interlayer Ti3C2Tx MXene Channels Seunghyun Hong, Peng Wang, Husam Niman Alshareef Considering that a solid in contact with a liquid bears surface charges, an impact of charged interfaces is of increased importance in understanding fluidic behaviors inside nanoconfined channels since they have a high surface-to-volume ratio. Here, we exploit 2D interlayer nanochannels with surface charges, formed between randomly stacked neighboring metal carbide and nitride (MXene) sheets, to investigate confined ionic motions under chemical potential gradients. Plenty of surface terminal groups, arising from etching and exfoliation processes during MXene synthesis, endow the planar sheets with negative surface charges and help create the interlayer spacing at the sub-nanometer scale. The MXene confined channels harness the chemical potential differences by salinity gradients via charge-selective ion transportation. Furthermore, coupled with the inherent photothermal conversion performance of MXene materials, the MXene capillaries convert thermochemical potential driven by local photothermal heating to an active ion flux from colder to hotter sides. The MXene-based ion conductor may be an important nanofluidic platform possibly for biomimetic sensory systems. |
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