Multiwalled Carbon Nanotube Thin Films Research Articles

Perylene derivative sensitized multi-walled carbon nanotube thin film

Perylene-sensitized multi-walled carbon nanotubes (PV-MWNT) have been prepared by a π-stacking between nanotubes and perylene derivatives, N, N′-diphenyl glyoxaline-3,4,9,10-perylene tetracarboxylic acid diacidamide (PV). The resultant nanocomposites have been characterized by transmission electron microscope (TEM), UV–vis absorption, photoluminescence (PL) and photocurrent spectra. Long range ordering can be observed in the form of PV-MWNT via π-stacking by TEM. Red-shift in the optical spectra consisting of the UV–vis absorption and PL spectra with the attraction of PV on the surface of the MWNTs were observed. The evident quenching in PL spectra of PV-MWNT was ascribed to the absorption and transfer of recombination energy by MWNT. Photosensitivity spectra demonstrated an increasing photocurrent in the ultraviolet region and a broadening photosensitivity in the red spectral region for solar cells based on PV-MWNT.

Electrical conductivity of multiwall carbon nanotubes thin films

Electrical characterization of multiwall carbon nanotubes thin film above room temperature is presented. The electrical conductance of the films shows a strong dependence on temperature, and is explained in terms of a simple activated model. Other mechanisms based on the Luttinger liquid and the disordered wire models for the transport properties are also discussed.

Investigation of the NO2 sensitivity properties of multiwalled carbon nanotubes prepared by plasma enhanced chemical vapor deposition

In the present work, multiwalled carbon nanotube (MWNT) thin films deposited by plasma enhanced chemical vapor deposition have been investigated as resistive gas sensors towards NO2. The sensor design is a platinum interdigitate electrode, fabricated by photolithography upon Si3N4 deposited on silicon, over which the MWNTs are deposited. Microstructural features as determined by scanning electron, transmission electron, and Raman spectroscopies have highlighted the growth of tubular carbon structures of 20–30 nm diameter and 150–200 nm length. Carbon nanotubes have shown a decreasing of their resistance upon exposure to NO2 gas (10–100 ppb) and the highest sensitivity at 165 °C working temperature. The time evolution of the electrical resistance at 165 °C as the sample was cycled through 500 ppm of NH3, 100 ppm of C6H6, water vapor, and 500 ppm of ethanol gases and dry air has been also reported. The variation of conductance in the presence of oxidizing or reducing gases is explained on the basis of charge transfer between the adsorbates and the nanotubes.

Multifunctional structural reinforcement featuring carbon nanotube films

Multiwalled carbon nanotube thin films were fabricated using catalytic chemical vapor deposition of xylene–ferrocene mixture precursor. The nanotube films were employed as inter-layers within composite systems to reinforce the interfaces between composite plies, enhancing laminate stiffness as well as structural damping. Experiments conducted using a piezo-silica composite beam with an embedded nano-film sub-layer indicated up to 200% increase in the inherent damping level and 30% increase in the baseline bending stiffness with minimal increase in structural weight. Scanning Electron Microscopy (SEM) characterization of the nano-film was also conducted to investigate the mechanics of stiffness and damping augmentation. The study revealed a fascinating network of densely packed, highly interlinked multiwalled nanotubes (MWNTs). This inter-tube connectivity resulted in strong interactions between adjacent nanotube clusters as they shear relative to each other causing energy dissipation within the nano-film. The cross-links between nanotubes also served to improve load transfer within the network resulting in improved stiffness properties.