monometallic and bimetallic ni and co catalytic nanoparticles supported on titanium dioxide (rutile phase) substrate were prepared by wet impregnation method. these nanoparicles were used as catalysts for synthesis of multiwalled carbon nanotubes (mwcnts) from acetylene decomposition at 700°c by the catalytic chemical vapor deposition (ccvd) technique. the nanomaterials (catalyst and cnts) were...

Jeong-O Lee el al. [Phy. Rev. B, 61, R16 362 (2000)] reported magnetoresistance and differential conductance measurements of multiwalled carbon nanotubes. The observed aperiodic conductance fluctuations and the negative magnetoresistance was interpreted to originate exclusively from changes in the density of states at the Fermi energy. We show that this interpretation is questionable and not su...

Individual multiwalled carbon nanotubes with a range of aspect ratios are subjected to cyclic axial compression to large strains using atomic force microscopy. Distinct elastic buckling and post-buckling phenomena are observed reproducibly and are ascribed to Euler, asymmetric shell buckling (i.e., kinking), and symmetric shell buckling. These show agreement with continuum theories that range f...

The La2NiO4 film was synthesized on the 304 stainless steel (SS) mesh. The hydrogen reduction of La2NiO4 generated homogeneous nanocatalyst particles (probably Ni/La2O3) over which methane was cracked, producing carbon nanotubes/microfibers and hydrogen. The carbon nanotubes/microfibers were strongly bonded to the SS mesh. It was observed that the methane conversion always reached its maximum a...

Composites of extracellular matrix proteins reinforced with carbon nanotubes have the potential to be used as conductive biopolymers in a variety of biomaterial applications. In this study, the effect of functionalization and polymer wrapping on the dispersion of multiwalled carbon nanotubes (MWCNT) in aqueous media was examined. Carboxylated MWCNT were wrapped in either Pluronic(®) F127 or gel...

We present strong evidence of Landau states formation in multiwalled carbon nanotubes with metallic or semiconducting outer shells, under magnetic fields as high as 60 T. Magnetoconductance data are found to converge to a gate-independent value for semiconducting shells, whereas for metallic shells, the Landau states introduce a strong reintroduction of backscattering and Fermi level pinning cl...

A highly focused electron beam can be used to shape nanodevices. We demonstrate electron beam etching of nanoholes through multiwalled carbon nanotubes ͑MWNTs͒ and niobium nanowires. Nanoholes, as small as ϳ2.5 nm in diameter, can be reproducibly fabricated. This technique can also be used to fabricate constrictions and larger nanoholes in MWNTs. We argue that with some improvement, this techniqu...

Spectroscopic analysis and atomic force microscopy (AFM) phase imaging studies show self-assembly of phenosafranin (PSF) to multiwalled carbon nanotubes (MWNTs). The shift in absorption spectra is associated with charge transfer of valence electrons from PSF to electron accepting sites on the MWNTs. The Raman-active disorder modes are used to fingerprint PSF attachment to MWNTs via defect state...

The controlled synthesis and growth of carbon nanotubes (CNTs) has been a long standing challenge in the fabrication of carbon based materials for electronic applications. Due to the sensitivity to small changes in their structure, the successful integration of CNTs on electronic devices is conditioned to the preservation of the graphitic network of single and multiwalled nanotubes from externa...

Tunneling spectroscopy measurements of single tunnel junctions formed between multiwalled carbon nanotubes (MWNTs) and a normal metal are reported. Intrinsic Coulomb interactions in the MWNTs give rise to a strong zero-bias suppression of a tunneling density of states that can be fitted numerically to the environmental quantum-fluctuation theory. An asymmetric conductance anomaly near zero bias...