Field Emission Properties of Cu-Filled Vertically Aligned Carbon Nanotubes Grown Directly on Thin Cu Foils

Copper-filled vertically aligned carbon nanotubes (Cu@VACNTs) were grown directly on Cu foil substrates of 0.1 mm thicknesses at different temperatures via plasma-enhanced chemical vapor deposition (PECVD). By circumventing the need for additional catalyst layers or intensive substrate treatments, our in-situ technique offers a simplified and potentially scalable route for fabricating Cu@VACNTs with enhanced electrical and thermal properties on thin Cu foils. Comprehensive analysis using field emission scanning microscopy (FESEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) mappings, and X-ray diffraction (XRD) revealed uniform Cu filling within the VACNTs across a range of synthesis temperatures (650 °C, 700 °C, and 760 °C). Field emission (FE) measurements of the sample synthesized at 700 °C (S700) showed low turn-on and threshold fields of 2.33 V/μm and 3.29 V/μm, respectively. The findings demonstrate the viability of thin Cu substrates in creating dense and highly conductive Cu-filled VACNT arrays for advanced electronic and nanoelectronics applications.

Evaluation of Time-Dependent Corrosion Inhibition Rate for f-MWCNT-BCP Composite Coatings on 316L Stainless Steel in Simulated Body Fluid for Orthopedic Implantation

A well-developed-multiwall carbon nanotube (f-MWCNT)/biphasic calcium phosphate (BCP) composites were synthesized using ultrasonication method for orthopedic implantation applications. The formation of composites and its phase was confirmed by using X-ray diffraction. The presence of various functional groups was identified by using Fourier transform infra-red (FT-IR) spectroscopy. The presence of f-MWCNT was confirmed by Raman spectroscopy. High-resolution transmission electron microscopy (HR-TEM) analysis revealed that BCP units were bound by the surface of f-MWCNTs. The synthesized composites were coated on medical grade 316L stainless steel substrates using electro deposition technique. To determine its corrosion resistance characteristics, the developed substrates were exposed to a simulated bodily fluid (SBF) solution for 0, 4, and 7 days. These results strongly suggest that the coated composites can be utilized for bone tissue repair.

Sb2Te3 nanoparticle-containing single-walled carbon nanotube films coated with Sb2Te3 electrodeposited layers for thermoelectric applications

Single-walled carbon nanotubes (SWCNTs) are promising thermoelectric materials owing to their flexibility and excellent durability when exposed to heat and chemicals. Thus, they are expected to be used in power supplies for various sensors. However, their thermoelectric performances are inferior to those of inorganic thermoelectric materials. To improve the thermoelectric performance while maintaining the excellent characteristics of SWCNTs, a novel approach to form inorganic thermoelectric layers on the SWCNT bundle surfaces using electrodeposition is proposed. We synthesized Sb₂Te₃ nanoparticle-containing SWCNT films and coated them with electrodeposited Sb₂Te₃ layers. The Sb₂Te₃ nanoparticles were synthesized via a spontaneous redox reaction, which were then added to a SWCNT dispersion solution, and films were produced via vacuum filtration. At higher nanoparticle contents in the films, the Sb₂Te₃ electrodeposited layers completely covered the SWCNT bundles owing to the increase in the concentration of precursor ions near the SWCNT bundle surface, which in turn was the result of melted nanoparticles. The thermoelectric performance improved, and the maximum power factor at approximately 25 °C was 59.5 µW/(m K²), which was 4.7 times higher than that of the normal SWCNT film. These findings provide valuable insights for designing and fabricating high-performance flexible thermoelectric materials.