arXiv subjects

Ravalika Sajja

Publications and source records attributed to Ravalika Sajja.

3 recordsLinked to original sources

arXiv2026

Enhanced Ionic Conductivity of confined Ionic-Liquid in Angstrom-scale 2D channels

Understanding ion-transport under molecular confinement is essential for developing next-generation energy technologies, where ionic motion often occurs within nanoscale or angstrom-scale channels. In this study, we use the model system of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([EMIM]+[TFSI]-) confined within angstrom-scale slit-shaped 2D channels fabricated via van der Waals assembly to exemplify a broader class of confined ionic liquids.This system provides a well-defined platform to unravel generic features of ion transport under extreme confinement. By systematically varying the channel height h, we demonstrate a non-monotonic conductivity dependence on confinement, with a maximum 26.7 S/m at confining height, 1.02 nm, over 30 times of the bulk value for these ionic liquids. The variation of conductivity with confinement arises from structural rearrangements of ionic layers in the slit channel. Enhanced values of conductivity occur under confinements that promote the breakup of ion pairs and larger clusters, thereby increasing the number of free ions. Stronger confinement (h, 0.68 nm) also leads to steric hindrance, lowering conductivity below bulk values. Furthermore, introducing co-solvents with a higher dielectric constant and lower viscosity, such as acetonitrile (ACN), amplifies conductivity to ~145 S/m. Comparative studies using ACN, dimethyl carbonate and diethyl carbonate highlight that both large dielectric constant and low viscosity critically govern ion transport under confinement, as also supported by molecular dynamics simulations. Overall, this work establishes confined [EMIM]+[TFSI]- as a representative system for probing mechanisms of nano- and angstrom-scale ion transport, demonstrating how nanoconfinement and the solvent environment can be systematically tuned to manipulate ionic conductivity at the molecular level.

physics.chem-ph↗

arXiv2023

Fabrication of angstrom-scale two-dimensional channels for mass transport

Fluidic channels at atomic scales regulate cellular trafficking and molecular filtration across membranes and thus play crucial roles in the functioning of living systems. However, constructing synthetic channels experimentally at these scales has been a significant challenge due to the limitations in nanofabrication techniques and the surface roughness of the commonly used materials. Angstrom-scale slit-like channels address this challenge, as these can be made with precise control over their dimensions and can be used to study the fluidic properties of gases, ions and water at unprecedented scales. Here, we provide a detailed fabrication method of the two-dimensional (2D) angstrom-scale channels, which can be assembled as a single channel or up to hundreds of channels made with atomic scale precision using layered crystals. The procedure includes the fabrication of the substrate, flake, spacer layer, flake transfers, van der Waals assembly, and post-processing. We further explain how to perform molecular transport measurements with the angstrom-scale channels, for the development of methods directed at unravelling interesting and anomalous phenomena that help shed light on the physics of nanofluidic transport systems. The procedure requires a total of 1 to 2 weeks for the fabrication of the 2D channel device and is suitable for users with prior experience in clean room working environments and nanofabrication.

physics.app-ph↗

arXiv2021

Hydrocarbon Contamination in Angstrom-scale Channels

Nonspecific molecular adsorption like airborne contamination occurs on most surfaces including those of 2D materials and alters their properties. While the surface contamination is studied using a plethora of techniques, the effect of contamination on a confined system such as nanochannels, nanopores leading to their clogging is still lacking. We report a systematic investigation of hydrocarbon adsorption in the angstrom slit channels of varied heights. Hexane is chosen to mimic the hydrocarbon contamination and the clogging of the angstrom-channels is evaluated via a Helium gas flow measurement. The level of the hexane adsorption, in other words, the degree of clogging depends on the size difference between the channels and hexane. A dynamic transition of the clogging and revival process is shown in sub-2 nm thin channels. Long-term storage and stability of our angstrom-channels is demonstrated here up to three years, alleviating the contamination and unclogging the channels using thermal treatment. This study highlights the importance of the nanochannels stability and demonstrates self-cleansing nature of sub-2 nm thin channels enabling a robust platform for molecular transport and separation studies. We provide a method to assess the cleanliness of the nanoporous membranes, which is vital for the practical applications of nanofluidics in various fields such as molecular sensing, separation and power generation.

physics.chem-ph↗