Drexel Researchers Unveil Breakthrough in MXene Nanoscroll Production

Philadelphia, PA – Researchers from Drexel University have reported a new process for producing MXene nanoscrolls, a one-dimensional conductive nanomaterial. This significant development comes nearly 15 years after their initial discovery of two-dimensional MXene materials.

Material Properties and Advantages

MXene nanoscrolls are remarkably thin, approximately 100 times thinner than a human hair, and boast higher conductivity than their two-dimensional MXene counterparts. The research team suggests these advanced materials could lead to substantial improvements in energy storage devices, biosensors, and wearable technology.

The findings, detailed in the journal Advanced Materials, describe a scalable method for manufacturing these nanoscrolls from a MXene precursor. This process allows for precise control over their unique shape and chemical structures.

"While two-dimensional morphology is important, one-dimensional morphology offers advantages in certain applications, comparable to using metal pipes or rebar instead of steel sheets."
– Yury Gogotsi, PhD, corresponding author

Converting 2D MXene flakes into 1D scrolls creates a tubular material. This distinct tubular geometry effectively bypasses nano-confinement effects often present in stacked 2D MXenes, thereby creating "highways" for rapid ion transport, explains Teng Zhang, PhD, a co-author. This structural advantage facilitates freer movement for ions and molecules, significantly reducing resistance.

While similar scroll structures exist for graphene (such as carbon nanotubes and graphene nanoscrolls), producing high-quality 1D scrolls from MXene – which offers richer chemistry, better processability, and superior conductivity – has historically posed a considerable challenge.

Production Process

The innovative process for creating these nanoscrolls begins with a multilayer MXene flake. Researchers meticulously control the chemical environment, utilizing water to alter the flakes' surface chemistry.

This controlled alteration leads to a structural asymmetry, known as a Janus reaction, which in turn induces lattice strain within the flake layers. The subsequent release of this internal strain causes the layers to naturally peel and curl into tightly wound tubular scrolls.

The team successfully applied this method to six distinct MXene types: two types of titanium carbide, niobium carbide, vanadium carbide, tantalum carbide, and titanium carbonitride. They consistently produced 10 grams of nanoscrolls with precise control over both their chemical composition and physical structure.

Potential Applications

The unique geometry of the nanoscrolls, coupled with their superior electrical conductivity and mechanical strength, unlocks novel behaviors applicable in chemical sensing and various functional composite materials.

In conventional stacked 2D structures, active sites for molecular adsorption are often inaccessible. The open, hollow architecture of the scroll, however, provides easy access for molecules – including large biomolecules – to the MXene surface. This feature, combined with high conductivity and mechanical stiffness, promises strong, stable signals for advanced biosensing, gas sensors, and electrochemical capacitors.

For wearable electronics and ionotronic devices, MXene scrolls offer both mechanical reinforcement and enhanced conductivity. Their rigid structure can firmly anchor into soft polymer matrices, providing strength while maintaining a robust conductive network. This enables the creation of stretchable composite materials that retain their electrical connection even under movement.

Furthermore, researchers discovered that the orientation of nanoscrolls in solution can be precisely controlled using an electric field. This capability allows for fabrication where scrolls align with fiber axes in functional textiles, yielding durable and highly conductive coatings.

Future Research and Superconductivity

The team plans to further investigate this controllable behavior and explore the material's quantum properties, specifically its potential for superconductivity.

Previously, superconductivity in this class of MXenes had only been observed in pressed pellets, not in solution-processed, mechanically flexible films. By utilizing niobium carbide scrolls, researchers have, for the first time, observed material changes that enable superconductivity in free-standing, macroscopic films. It is hypothesized that the scrolling process introduces specific lattice strain and curvature that stabilize this superconducting state.

This discovery represents a critical breakthrough, transforming MXene superconductivity into a practical property of the nanomaterial. The methods described could facilitate the processing of superconducting MXenes into flexible films, coatings, or wires at room temperature, paving the way for potential superconducting interconnectors or quantum sensors. The team anticipates a wave of further discoveries related to scrolling-induced phenomena.