Abstract
Solid-liquid interfaces display a wealth of emerging phenomena at nanometer scales, which are at the root of their technological applications. While the interfacial structure and chemistry have been intensively explored, the potential coupling between liquid flows and the solid’s electronic degrees of freedom has been broadly overlooked up till now. Despite several reports of electronic currents induced by liquids flowing in various carbon nanostructures, the mechanisms at stake remain controversial. Here, we unveil the molecular mechanisms of interfacial liquid-electron coupling by investigating flow-induced current generation at the nanoscale. We use a tuning fork atomic force microscope to deposit and displace a micrometric liquid droplet on a multilayer graphene sample, and observe an electronic current induced by the droplet displacement. The measured current is several orders of magnitude larger than previously reported for water on carbon, and further boosted by the presence of surface wrinkles on the carbon surface. Our results point to a peculiar momentum transfer mechanism between the fluid molecules and graphene charge carriers, mediated mainly by the solid’s phonon excitations. These findings open new avenues for active control of nanoscale liquid flows through the solid walls’ electronic degrees of freedom.
- Received 28 June 2022
- Revised 27 October 2022
- Accepted 12 January 2023
DOI:https://doi.org/10.1103/PhysRevX.13.011020
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
Published by the American Physical Society
Physics Subject Headings (PhySH)
Focus
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Popular Summary
Solid-liquid interfaces display a wealth of emerging phenomena at nanometer scales, which are at the root of their technological applications. While the interfacial structure and chemistry have been intensively explored, the potential coupling between liquid flows and the solid’s electronic degrees of freedom has been largely overlooked. Here, we unveil the molecular mechanisms of interfacial liquid-electron coupling by investigating flow-induced current generation at the nanoscale.
This work required the development of a new experimental instrument that allows us to control the motion of a micrometrical drop at the mesoscale on multilayer graphene surfaces with unprecedented accuracy. We use a tuning fork atomic force microscope to deposit and displace a micrometric liquid droplet on a multilayer graphene sample and observe an electric current induced by the droplet displacement. The measured current is several orders of magnitude larger than previously reported for water on carbon and is further boosted by the presence of surface wrinkles on the carbon surface. Our results point to a peculiar momentum-transfer mechanism between the fluid molecules and graphene charge carriers, mediated mainly by the solid’s phonon excitations.
Our experiments unveil the intimate mechanisms of hydroelectronic couplings, highlighting that phonon winds are at the root of liquid-flow-induced electronic currents on multilayer graphene materials. These findings open new avenues for active control of nanoscale liquid flows through the solid walls’ electronic degrees of freedom.