Direct 3D printing of graphene using capillary suspensions

Area of Science:

• Materials Science
• Nanotechnology
• Additive Manufacturing

Background:

• Conventional 3D printing of graphene often requires complex ink formulations with high polymer content or post-processing like freeze-drying.
• These limitations hinder efficient fabrication and property control of 3D graphene structures.

Purpose of the Study:

• To introduce a novel graphene capillary suspension (GCS) for simplified 3D printing.
• To demonstrate the GCS's suitability for direct writing of graphene structures with desirable properties.

Main Methods:

• Formulation of a graphene capillary suspension with graphene nanoparticles, carboxymethyl cellulose (CMC), and octanol.
• Direct writing and air-drying at room temperature to fabricate a lattice structure.
• Characterization of the printed structure's porosity, mechanical strength, and electrical conductivity.
• X-ray tomography to analyze the internal architecture.

Main Results:

• The GCS exhibited suitable rheological properties for direct writing.
• The printed structure achieved 81% porosity, 1.3 MPa compression strength, and 250 S m⁻¹ electrical conductivity after air drying.
• Heat treatment at 350 °C increased conductivity to 2370 S m⁻¹ while reducing strength to 0.4 MPa.
• X-ray tomography revealed that GCS formation prevents 2D material ordering during extrusion.

Conclusions:

• Graphene capillary suspensions offer a simplified approach for 3D printing graphene structures.
• This method avoids complex drying steps and excessive polymer binders, facilitating shape retention and property control.
• The GCS approach is a promising alternative for fabricating advanced 3D graphene materials.