About The Event
Ionic selectivity and memory under angstrom-scale confinement
Understanding molecular transport in nano/angstrom scale channels has practical relevance in applications such as membrane desalination, blue energy, supercapacitors and batteries, as well as in understanding ionic flow through biological channels. Synthetic Å-channels are now a reality with the emergence of several cutting-edge bottom-up and top-down fabrication methods. In particular, the use of atomically thin 2D-materials and nanotubes as components to build fluidic conduits has pushed the limits of fabrication to the Å-scale. In this talk, I will discuss about angstrom (Å)-scale capillaries which are rectangular slit-shaped channels and are created by extracting one-atomic layer out of a crystal [1]. The Å-capillary is an antipode of graphene and can be dubbed as “2D-nothing”. What is intriguing here is, the dimensions of the thinnest channels being comparable to the size of a water molecule.
The Å-capillaries have helped probe several intriguing molecular-scale phenomena experimentally, including: water flow under extreme atomic-scale confinement [1] complete steric exclusion of ions [3,5], specular reflection and quantum effects in gas reflections off a surface [2,7], voltage gating of ion flows [4] translocation of DNA [6]. I will present ionic flows induced by stimuli (electric, pressure, concentration gradient) and discuss the importance of ionic parameters that are often overlooked in the selectivity between ions [7], along with ionic memory effects [8].
References:
[1] B. Radha et al., Nature 538, 222 (2016).
[2] A. Keerthi et al., Nature (2018), 558, 420.
[3] A. Esfandiar et al., Science 358, 511 (2017).
[4] T. Mouterde et al., Nature 567, 87 (2019).
[5] K. Gopinadhan et al., Science 363, 145 (2019).
[6] Y. You, A.Ismail et al., Annual Reviews for Materials Research 52, 189, (2022).
[7] S. Goutham et al., Nature Nanotechnology 2023, 18, 596.
[8] P. Robin et al., Science (2023), 379, 161.
