Challenges in Fabricating Copper Nanotubes

copper nanotubes, also called carbon nanotubes (CNTs) or multi-walled CNTs (MWCNTs), have the potential to deliver unprecedented electrical/thermal and mechanical performances in a wide variety of energy devices and sensors. The conductive properties of Cu make it attractive for electronic interconnects and for applications in the field of fuel cells and batteries.

To maximize the potential for Cu/CNT composites to achieve superior electrical and thermal conductivity, several issues need to be addressed: First, uniform CNT and Cu spatial distribution needs to be achieved in both powder-processed and electrodeposited Cu/CNT composites [53-57]. Second, enhancing CNT-Cu interfacial interaction is critical to improve stress transfer and electron/phonon transport through the nanocomposite matrix and enhance load sharing between nanotubes.

Third, modifying CNT attributes (e.g., length, orientation) during composite fabrication can modify nanotube performance and compromise initial versus nanotube structure studies [111]. This is particularly true of mixing-based fabrications (mainly powder process) that break and shorten or misalign CNTs while preparing their nanocomposites.

Fortunately, many of these fabrication issues can be mitigated or even avoided using more benign fabrication methods like template electrodeposition (two-stage process) that preserve CNT attributes during processing, especially for initial performance versus nanotube structure studies. This approach can be especially helpful for addressing the challenging issues of obtaining individually dispersed long CNTs for homogeneous composite fabrication, controlling nanotube alignment, and ensuring CNT-Cu interfacial bonding through oxygen, all of which are required to maximize the strength of CNT-based Cu/CNT composites.