We have created PMMA-CNT matrices by embedding opened-tip vertically aligned multiwalled carbon nanotubes (VA-MWCNTs) with poly(methyl methacrylate) (PMMA). These PMMA-CNT matrices are excellent electron field emitters with an emission threshold field of 1.675 V/μm, more than 2-fold lower that that of the as-grown sample. In addition, the emission site density from these matrices is high, merel...

Carbon nanotubes (CNTs) have a broad range of applications and are generally considered human-engineered nanomaterials. However, carbon nanostructures have been found in ice cores and oil wells, suggesting that nature may provide appropriate conditions for CNT synthesis. During forest wildfires, materials such as turpentine and conifer tissues containing iron under high temperatures may create ...

Functionalized MWCNTs are used in many commercial and biomedical applications, but their potential health effects are not well defined. We investigated and compared cytotoxic, genotoxic/oxidative, and inflammatory effects of pristine and carboxyl MWCNTs exposing human respiratory (A549 and BEAS-2B) cells to 1-40 μg/mL of CNTs for 24 h. Both MWCNTs induced low viability reduction (by WST1 assay)...

Multi-walled carbon nanotube (MWCNT)/Portland cement (PC) composites have been prepared to evaluate their electromagnetic wave absorbing properties. The effects of MWCNTs content and sample thickness were discussed in the frequency ranges of 2–18 GHz. Results show that the absorbing properties of cement-based composites are affected by the content of MWCNT and the thickness of the samples. When...

We examined the structure, morphology, and orientation of catalyst nanoparticles used for seeding and growing multiwall carbon nanotubes (MWCNTs) by plasma enhanced chemical vapor deposition in CH4/H2 gas mixtures. Iron catalyst nanocrystals are converted to Fe3C in CH4/H2 plasmas and the MWCNTs grow from Fe3C nanocrystals. Initially faceted and equiaxed catalyst nanocrystals are distorted and ...

This study focuses on different techniques for dispersing Multi-Walled Carbon Nanotubes (MWCNTs) in cementitious materials. The impact of dispersion is observed through electrical resistivity and mechanical properties composites. Two contents (0.5 1% by mass cement) MWCNTs are investigated three were used to disperse CNTs water sonication: (i) pristine, P-CNT, (ii) functionalized carbon nanotub...

MWCNTs produced by using Chemical Vapor Deposition (CVD) technique were functionalized with nitric and sulfuric acid to ensure a good dispersion in an aqueous solution. The FTIR analysis further confirmed the presence of carboxyl and hydroxyl groups on the surface of MWCNTs after acid treatment. The two types of MWCNTs composites were prepared using pristine and ...

Efficacious regulation of the geometric and electronic structures carbon nanomaterials via introduction defects their synergy is essential to achieving good electrochemical performance. However, guidelines for designing hybrid materials with advantageous fundamental understanding electrocatalytic mechanisms remain unclear. Herein, superfine Pt PtCu nanoparticles supported by novel S,N-co-doped ...

Using an atomic force microscope (AFM) at a controlled contact force, we report the electrical signal response of multi-walled carbon nanotubes (MWCNTs) disposed on a golden thin film. In this investigation, we highlight first the theoretical calculation of the contact resistance between two types of conductive tips (metal-coated and doped diamond-coated), individual MWCNTs and golden substrate...

Reviewing experimental results and based on the physical reasoning, we present a basic circuit model for Multiwall carbon nanotubes (MWCNTs), which can simulate different experimental results. Investigation of different results confirms the severe effects of fabrication process (nanotube and contacts) on electronic properties of the MWCNTs. The circuit model has been developed to show the perfo...