New evidence on the dielectric constant and conductivity of water.

Water is fundamental to life due to its unique properties, which surprisingly remain partly elusive despite decades of research. In particular, it exhibits unexpected behaviors at the nanoscale.

A team at the University of Manchester, led by Dr. Laura Fumagalli and Prof. Andre Geim (winner of the 2010 Nobel Prize in Physics for graphene research), in collaboration with Prof. Giorgio Ferrari of the Politecnico di Milano, has discovered that water confined within channels only a few molecular layers thick exhibits along the direction of the channel a dielectric response and electrical conductivity significantly higher than that observed at the macroscale — by up to an order of magnitude. These values are similar to those found in advanced ferroelectric and superionic materials.

The study, published in Nature, was made possible by combining an advanced characterization technique, scanning dielectric microscopy, with the ability to nanofabricate two-dimensional channels only a few atomic layers thick. Unlike previous findings, which showed a drastic reduction in dielectric properties in the direction perpendicular to the channels, extending the measurements to a frequency range from a few kHz to the GHz regime revealed an unexpected increase in the electrical response of water in the direction parallel to the channels.

This pronounced difference in behavior between the two directions opens new avenues for understanding the properties of water and how it interacts with and influences the behavior of biological molecules. This finding has broad implications for chemistry and biology, as well as for the development of next-generation batteries and electrochemical devices.