Probing water structures in nanopores using tunneling currents

TL;DR

This study combines molecular dynamics and quantum scattering to investigate how water's structure inside nanopores affects electronic tunneling currents, revealing a structural transition that influences conductance.

Contribution

It introduces a novel approach to probe water structures in nanopores via tunneling currents, linking structural motifs to electronic transport properties.

Findings

Current deviates from exponential at ~8 Å pore diameter

Structural transition from bulk-like to nanodroplet water occurs

Results are experimentally testable with current technology

Abstract

We study the effect of volumetric constraints on the structure and electronic transport properties of distilled water in a nanopore with embedded electrodes. Combining classical molecular dynamics simulations with quantum scattering theory, we show that the structural motifs water assumes inside the pore can be probed directly by tunneling. In particular, we show that the current does not follow a simple exponential curve at a critical pore diameter of about 8 {\AA}, rather it is larger than the one expected from simple tunneling through a barrier. This is due to a structural transition from bulk-like to "nanodroplet" water domains. Our results can be tested with present experimental capabilities to develop our understanding of water as a complex medium at nanometer length scales.