A sedimentation study of graphene oxide in aqueous solution using gradient differential centrifugation

Area of Science:

• Materials Science
• Physical Chemistry
• Nanotechnology

Background:

• Graphene oxide (GO) is a promising nanomaterial with diverse applications.
• Understanding GO sedimentation behavior in aqueous solutions is crucial for its processing and application.
• Current theories may not fully capture the complex factors influencing GO sedimentation.

Purpose of the Study:

• To investigate the sedimentation of graphene oxide (GO) sheets in aqueous solutions.
• To determine the key factors affecting GO sedimentation velocity and behavior.
• To evaluate the effectiveness of gradient differential centrifugation for GO separation.

Main Methods:

• Gradient differential centrifugation was employed to separate GO sheets.
• Analysis included FT-IR spectroscopy, XRD, optical microscopy, and particle size measurements.
• Mathematical modeling was used to probe the underlying sedimentation mechanisms.

Main Results:

• GO sheets ranging from 400-1100 nm (2-17 layers) were separated.
• Hydration degree and d-spacing were dominant factors influencing GO sedimentation.
• Highly oxidized GO sheets exhibited higher hydration and sedimentation resistance.
• Larger d-spacing enhanced hydration, reduced density, and lowered sedimentation velocity.

Conclusions:

• Hydration and d-spacing play critical roles in GO sedimentation, overriding lateral size effects.
• Gradient differential centrifugation is effective for sorting GO sheets based on hydration and thickness.
• The study highlights limitations in current GO sedimentation theories and offers insights for future research.