High-Pressure Raman Study of Graphite–Water Mixtures: Absence of Intercalation up to 10 GPa

Raman spectra of graphite–water mixtures were investigated under pressures up to 10 GPa using diamond anvil cells (DACs) to examine the possibility of water intercalation into graphite. Although the kinetic diameter of water molecules is expected to decrease upon solidification near 1 GPa, no significant spectral changes were observed in either the graphite or water Raman features. The G and 2D bands of graphite exhibited regular blue shifts with pressure, consistent with standard lattice compression, while water maintained its characteristic O–H stretching behavior. These findings suggest that water remains largely excluded from graphite interlayers under the examined pressure range. Previous studies have proposed that surface interactions with water may facilitate local sp²-to-sp³ rehybridization under extreme conditions; therefore, further investigations at higher pressures are planned to explore the change in the onset of graphite-to-diamond transition in aqueous environments.