Liquid-like and solid-like acetonitrile intercalated into graphite oxide as studied by the spin probe technique

Area of Science:

• Materials Science
• Physical Chemistry
• Nanotechnology

Background:

• Graphite oxide (GO) is a layered material with potential applications in energy storage and composites.
• Understanding the behavior of guest molecules within the GO inter-plane space is crucial for optimizing its properties.
• Acetonitrile is a common polar aprotic solvent with relevance in electrochemical applications.

Purpose of the Study:

• To investigate the molecular dynamics and mobility of acetonitrile (ACN) confined within the graphite oxide inter-plane space.
• To determine the phase behavior (liquid-like vs. solid-like) of intercalated acetonitrile.
• To correlate the micro-viscosity of intercalated acetonitrile with temperature and intercalation amount.

Main Methods:

• Utilized the spin probe technique to monitor the molecular mobility of acetonitrile.
• Employed electron paramagnetic resonance (EPR) spectroscopy to analyze the spin probe dynamics.
• Varied temperature and the amount of intercalated acetonitrile to observe changes in mobility and phase.

Main Results:

• Identified the simultaneous presence of both liquid-like and solid-like acetonitrile phases within the graphite oxide inter-plane space.
• Demonstrated that the ratio of these two phases is temperature-dependent.
• Quantified the micro-viscosity of the liquid-like intercalated acetonitrile, finding it to be higher than bulk acetonitrile and influenced by the intercalation level.

Conclusions:

• The confinement within graphite oxide significantly alters the molecular mobility and phase behavior of acetonitrile.
• A temperature-controlled equilibrium exists between liquid-like and solid-like acetonitrile within the GO interlayers.
• The findings provide insights into solvent-graphene interactions and the properties of intercalated materials.