The Journal of Physical Chemistry C

Water is the matrix of life, and its confinement in nanocavities is a central topic from geophysics to nanotribology. Phyllosilicate layered minerals provide natural nanocavities for water due to their capacity to hydrate by confining water molecules in the interlamellar space. However, the hydration of phyllosilicates at the nanoscale is not a fully understood process and depends on the geological specimens. In this work, we report the formation of aqueous nanochannels in the interlamellar space of ultrathin clinochlore phyllosilicate mineral using infrared scattering-type scanning near-field optical microscopy and Kelvin probe force microscopy. We demonstrate that nanoconfinement of water in clinochlore changes the overall mechanical, optical, and dielectric properties of the system. We propose a capacitive model that describes the dielectric response of the aqueous nanochannels. Our model is endorsed by a robust crystal truncation rod analysis of synchrotron X-ray diffraction data. We found that clinochlore termination combines hydrated structures ordered along the c-axis. We also find evidence of ice-like behavior of the water nanoconfined in clinochlore by Fourier-transform infrared spectroscopy. Notably, our work introduces clinochlore as a natural platform for water confinement in two-dimensional systems that can be engineered for several applications in the frontiers of nanotechnology.