Periodic Reporting for period 3 - AngstroCAP (Fundamental and Applied Science using Two Dimensional Angstrom-scale capillaries)
Reporting period: 2023-02-01 to 2024-07-31
Water is the most abundant liquid on Earth. Essential for life, it is part of nearly every single biological, geological and (electro) chemical process. The structure and dynamics of the bonding in water and the water flows in such confinement remains under study. My ERC StG, AngstroCAP project will utilize angstrom-scale capillary devices to investigate the confined water. These devices are in a lab-on-a-chip type configuration with angstrom-scale channels and atomically smooth walls. The project will assemble capillaries of a few microns in length, by sandwiching two blocks of layered crystals, separated by an atomically thin 2D-crystal spacer stripes. Inside these channels, the dynamics of water flows will be investigated along with that of water-salt solutions. We study size selective sieving of ions and molecules using these channels to probe desalination mechanisms from a fundamental science perspective.
Simultaneously, AngstroCAP investigates gas flows in atomic scale confinement. Gas flows in angstrom-scale constrictions are of significant importance for gas extraction and separation processes. In the case of extremely narrow pores which are much smaller than the mean free diffusion path of gas molecules, the gas flows can be described by conventional Knudsen theory. Here, the diffusing molecules randomly bounce back or scatter from the walls of the pores rather than colliding with each other. Until now, researchers didn’t know at which scale the Knudsen description would break down. We have shown that it holds true, even at the ultimate atomic limit. Our method is simple and robust for quantification of pores through gas flows and can be used for molecular-separation, sensing and monitoring gases and in single quantum-emitters.
The overall objectives of the AngstroCAP project are two-fold
Objective 1: To utilize angstrom-scale capillaries constructed out of two-dimensional (2D) materials as a versatile platform for studying confinement effect on water.
Objective 2: To construct new types of angstrom-scale 2D-pores from these capillaries for studying gas flows, volatile organic molecule adsorption, biomolecular translocation.
Simultaneously, AngstroCAP investigates gas flows in atomic scale confinement. Gas flows in angstrom-scale constrictions are of significant importance for gas extraction and separation processes. In the case of extremely narrow pores which are much smaller than the mean free diffusion path of gas molecules, the gas flows can be described by conventional Knudsen theory. Here, the diffusing molecules randomly bounce back or scatter from the walls of the pores rather than colliding with each other. Until now, researchers didn’t know at which scale the Knudsen description would break down. We have shown that it holds true, even at the ultimate atomic limit. Our method is simple and robust for quantification of pores through gas flows and can be used for molecular-separation, sensing and monitoring gases and in single quantum-emitters.
The overall objectives of the AngstroCAP project are two-fold
Objective 1: To utilize angstrom-scale capillaries constructed out of two-dimensional (2D) materials as a versatile platform for studying confinement effect on water.
Objective 2: To construct new types of angstrom-scale 2D-pores from these capillaries for studying gas flows, volatile organic molecule adsorption, biomolecular translocation.
We, the AngstroCAP project team, have progressed well on all of the work packages of the project as outlined below.
We have successfully designed fabrication methods of angstrom capillaries and fabricated several devices, while improving the design by trial and error (WP1 and WP2, PDRA1 and PDRA2 working on them). One review article has been published along with one protocol methods paper. We have made significant progress in developing the new method of making 2D pores by using microtomy. The initial months were dedicated to training and developing protocols for the methods. Following this, we have experimented with several 2D-materials’ slicing, and the results are now published as a manuscript.
We have obtained good results on hydrocarbon gas flows through angstrom capillaries and an invited article from the team is published in “emerging investigators collection” of RSC Nanoscience journal. One team member has worked on developing the layer by layer assembly protocols, and another PDRA has established the measurement techniques of biomolecular translocation in our group.
In terms of outputs: 10 refereed publications with the ERC grant acknowledged.
The PI and the team has attended several conferences and workshops (some virtually and few in person) along with PI giving lectures. A few to name are Materials Research Society Fall meeting 2022 (Invited lecture x2), Pacifichem 2021 (Young giants in Nanoscience, invited lecture), Liquid Matter 2021 (plenary lecture), International Winter school on Electronic Properties of Novel Materials 2020 (invited lecture), RSC Faraday online symposia 2020 (award lecture), World Laureates Forum 2020 (Invited lecture), CENT-MIT seminar series 2020 (invited lecture).
We have successfully designed fabrication methods of angstrom capillaries and fabricated several devices, while improving the design by trial and error (WP1 and WP2, PDRA1 and PDRA2 working on them). One review article has been published along with one protocol methods paper. We have made significant progress in developing the new method of making 2D pores by using microtomy. The initial months were dedicated to training and developing protocols for the methods. Following this, we have experimented with several 2D-materials’ slicing, and the results are now published as a manuscript.
We have obtained good results on hydrocarbon gas flows through angstrom capillaries and an invited article from the team is published in “emerging investigators collection” of RSC Nanoscience journal. One team member has worked on developing the layer by layer assembly protocols, and another PDRA has established the measurement techniques of biomolecular translocation in our group.
In terms of outputs: 10 refereed publications with the ERC grant acknowledged.
The PI and the team has attended several conferences and workshops (some virtually and few in person) along with PI giving lectures. A few to name are Materials Research Society Fall meeting 2022 (Invited lecture x2), Pacifichem 2021 (Young giants in Nanoscience, invited lecture), Liquid Matter 2021 (plenary lecture), International Winter school on Electronic Properties of Novel Materials 2020 (invited lecture), RSC Faraday online symposia 2020 (award lecture), World Laureates Forum 2020 (Invited lecture), CENT-MIT seminar series 2020 (invited lecture).
The AngstroCAP grant team members have made several original contributions, significantly extended the capabilities of nanofluidics beyond the state of the art, combining diverse materials and unconventional fabrication methods. For instance, the PI together with the research team have shown the selectivity between same-charge ions with similar hydrated diameters (Nature nanotechnology 2023).
Membrane-based applications such as osmotic power generation, desalination and molecular separation would benefit from decreasing water friction in nanoscale channels. However, mechanisms that allow fast water flows are not fully understood yet. The AngstroCAP teamreported that angstrom-scale capillaries made from atomically flat crystals and study the effect of confining walls’ material on water friction (Nature Communications 2021). A massive difference is observed between channels made from isostructural graphite and hexagonal boron nitride, which is attributed to different electrostatic and chemical interactions at the solid-liquid interface. In collaboration with Prof Radenovic's group (EPFL, Switzerland), we probed the 2D-confinement on organic liquids, where native defects on hBN act as nanoscale probes with super-resolution microscopy (Nature Materials 2023). Our team in collaboration with Prof Bocquet's group (ENS Paris, France), we have reported neuromorphic memory using Å-channels, where electrolytes in 2D nanochannels develop long-term memory, from tens of minutes to hours (Science 2023).
Membrane-based applications such as osmotic power generation, desalination and molecular separation would benefit from decreasing water friction in nanoscale channels. However, mechanisms that allow fast water flows are not fully understood yet. The AngstroCAP teamreported that angstrom-scale capillaries made from atomically flat crystals and study the effect of confining walls’ material on water friction (Nature Communications 2021). A massive difference is observed between channels made from isostructural graphite and hexagonal boron nitride, which is attributed to different electrostatic and chemical interactions at the solid-liquid interface. In collaboration with Prof Radenovic's group (EPFL, Switzerland), we probed the 2D-confinement on organic liquids, where native defects on hBN act as nanoscale probes with super-resolution microscopy (Nature Materials 2023). Our team in collaboration with Prof Bocquet's group (ENS Paris, France), we have reported neuromorphic memory using Å-channels, where electrolytes in 2D nanochannels develop long-term memory, from tens of minutes to hours (Science 2023).