PhD Student at École de technologie supérieure studying Carbon Nanotube MEMS.
You will be left astounded when you get to know about its potential and uses.
Carbon nanotubes are remarkable materials that are set to supercede silicon-based technologies in the future.
Sci-fi stuff! Do you fancy an elevator ride to space or drive a car powered by hydrogen with no emissions? These are some of the mind-boggling applications possible with carbon nanotubes.
Too good to be true? Of course, one might argue that there is no sign of hydrogen cars (at least commercially) or space elevators, but considering how fast paced scientific advancement is, it is not a distant dream by any standards.
One of the main areas of application of nanotubes is electronics. Miniaturization of microchips is fast approaching its limit and carbon nanotubes are the best hopes for further miniaturization. Carbon nanotube transistors are currently being investigated as a replacement for conventional silicon transistors. Computers powered by nanotubes can be expected to be much faster and more powerful than today's computers with lower power consumption.
So how do they look? As the name suggests, carbon nanotubes are just hollow tubes/cylinders composed of pure carbon. Based on the structure, nanotubes can be further classified into single-walled and multi-walled nanotubes. Multi-walled nanotubes are basically concentric layers of nanotubes inside each other, and can be thought of as a "Russian doll".
Companies like Intel and IBM are now switching their focus to commercializing nanotube products. Carbon fiber, which is used in the automotive industry to reduce weight and improve strength is a very good example of commercialization. DexMat is a company that specializes in nanotube products.
Everything seems good BUT as with any material, there are certain limitations associated with nanotubes, primarily cost. Manufacturing nanotubes requires expensive tools, which lead to higher costs. The other limiting factor is toxicity. Nanotubes are highly toxic and this limits their use in biological applications.
Abstract: We introduce membrane pseudocapacitive deionization (MPDI) of a hybrid cell consisting of one electrode of hydrated vanadium pentoxide (hV2O5) decorated on multi-walled carbon nanotubes electrode (MWCNT) and one electrode of activated carbon. This hybrid system enables sodium removal by pseudocapacitive intercalation to MWCNT-hV2O5 electrode and chloride removal by non-Faradaic electrosorption of the porous carbon electrode. MWCNT-hV2O5 electrode was synthesized by electrochemical deposition of hydrated vanadium pentoxide on the MWCNT paper. The stable electrochemical operating window for MWCNT-hV2O5 electrode is identified between -0.5 V and +0.4 V vs. Ag/Cl which provides a specific capacity of 44 mAh/g (corresponds with 244 F/g) in aqueous 1 M NaCl. The desalination performance of the MPDI system was investigated in aqueous 200 mM NaCl (brackish water) and 600 mM NaCl (sea water) solutions. With the aid of an anion and a cation exchange membrane, the MPDI hybrid cell was operated from -0.4 V to +0.8 V cell voltage without crossing the reduction and oxidation potential limit of both electrodes. For the 600 mM NaCl solution, the NaCl salt adsorption capacity of the cell was 23.6±2.2 mg/g which is equivalent to 35.7±3.3 mg/g as normalized to the mass of the MWCNT-hV2O5 electrode. Additionally, we propose a normalization method for the electrode material with Faradaic reactions based on sodium uptake capacities.
Pub.: 26 Jul '17, Pinned: 26 Sep '17
Abstract: Single-walled carbon nanotubes (SWNTs) have potential for creating high performance gas sensors, but the number of gases that can be detected is still limited and the sensitivity needs further improvement. Here, large-area SWNT films directly synthesized by chemical vapor deposition are configured into gas sensors for a range of toxic gases such as NH3, NO, and NO2. In particular, a SWNT-Fe2O3 composite film obtained via a simple annealing process produces a stable response to H2S and shows enhanced sensitivity to NO2 and at room temperature, compared with pristine SWNT films. Formation of uniform Fe2O3 nanoparticles throughout the porous film is responsible for improved performance and enabling sensing to more gases, and removes conventional steps such as chemical functionalization or doping. Flexible sensors that can be bent to large angles repeatedly are also demonstrated. SWNT films containing a large amount of residual catalyst can be directly manufactured into large-area, flexible or wearable, thin film or textile-configured sensors for various toxic gases.
Pub.: 11 Feb '17, Pinned: 13 Apr '17
Abstract: In this work, ZnO-decorated multi-walled carbon nanotube (MWCNT) nanocomposites prepared using an in-situ method involving the thermal evaporation of Zn powders in the presence of MWCNTs. The gas sensing characteristics of the MWCNT/ZnO nanocomposites are studied, and results for the material characterizations for the synthesized nanocomposites confirm the formation of well-distributed ZnO nanoparticles onto MWCNTs, creating MWCNT/ZnO nanocomposites. The gas sensing properties of the MWCNT/ZnO nanocomposite gas sensor, such as response, cross-sensitivity, and response-recovery time, are investigated and compared with a bare MWCNT sensor. The decoration of ZnO nanoparticles greatly improves the gas sensing properties of bare MWCNTs. We discussed the possible mechanisms for the enhancement of sensing capabilities. The results suggest that decoration of n-type semiconducting oxide materials, such as ZnO in the form of nanoparticles, is a promising strategy for improvement of gas sensing properties of p-MWCNTs.
Pub.: 03 Apr '17, Pinned: 13 Apr '17
Abstract: Naloxone (NLX) is a pharmaceutical used as opioid antagonist. A molecular imprinted polymer electrochemical sensor for simple and rapid detection of NLX was prepared through the modification of commercial available screen printed carbon electrode (SPCE). The SPCE was modified with multi-walled carbon nanotubes (MWCNT) by drop coating to increase the signal response and improve the sensitivity. The MIP preparation was carried out via in situ electropolymerization using 4-aminobenzoic acid (4-ABA) as functional monomer. The morphology of the obtained sensor was characterized by scanning electron microscopy (SEM). Several parameters controlling the preparation and performance of the MIP sensor were studied and optimized. The electrochemical behavior of NLX at MIP and control non-imprinted (NIP) sensor was evaluated by differential pulse voltammetry (DPV), demonstrating a better MIP response and the success of the imprinting. The proposed MIP/MWCNT/SPCE sensor showed a linear relationship between peak current intensity and NLX concentration in the range between 0.25 and 10.0 μM, with limits of detection (LOD) and quantification (LOQ) of 0.20 μM and 0.67 μM respectively. The repeatability and reproducibility were also tested with relative standard deviations (RSD) of 4.6 and 9.6% respectively. Moreover, the applicability of the method was successfully confirmed with detection of NLX in biological samples (urine and human serum). The sensor is promising to be used for screening NLX in point-of-care people with opioid overdose.
Pub.: 08 Dec '16, Pinned: 12 Apr '17
Abstract: The aim of this work was to formulate chitosan-folate conjugated multi-walled carbon nanotubes for the lung cancer targeted delivery of docetaxel. The chitosan-folate conjugate was synthesized and the conjugation was confirmed by Fourier transform infrared spectroscopy. The multi-walled carbon nanotubes were characterized for their particle size, polydispersity, zeta potential, surface morphology, drug encapsulation efficiency and in vitro release study. The in vitro cellular uptake, cytotoxicity, and cell cycle analysis of the docetaxel/coumarin-6 loaded multi-walled carbon nanotubes were carried out to compare the effectiveness of the formulations. The biocompatibility and safety of chitosan-folate conjugated multi-walled carbon nanotubes was analyzed by lung histopathology in comparison with marketed docetaxel formulation (Docel™) and acylated multi-walled carbon nanotubes. The cellular internalization study shown that the chitosan-folate conjugated multi-walled carbon nanotubes could be easily internalized into the lung cancer cells through a folate receptor-mediated endocytic pathway. The IC50 values exhibited that chitosan-folate conjugated multi-walled carbon nanotubes could be 89-fold more effective than Docel™ in human lung cancer cells (A549 cells).
Pub.: 27 Mar '17, Pinned: 12 Apr '17
Abstract: In this study, a novel nanocomposite material consisted of oxygen-doped, nitrogen-rich carbon nanoribbons polymer and single-walled carbon nanotubes (ONPCNRs/SWCNTs) has been facilely synthesized through simply electrostatic interaction process using poly(diallyldimethylammonium chloride) polycationic compound (PDDA). During the synthesis, the N-containing of ONPCNRs could undergo protonation to produce protonated compound under pH 6.5 condition, which could improve electrocatalytic activity of the vertically aligned N-containing ONPCNRs/SWCNTs nanocomposite due to the electron withdrawing ability of nitrogen atoms to create net positive charge on the adjacent carbon atoms in the PDDA-modified SWCNTs (PDDA/SWCNTs) plane. Meanwhile, due to the high N-doping ONPCNRs have high adsorption capacity and selectivity toward H2O2 adsorption, the combination of PDDA/SWCNTs and use of high N-doping ONPCNRs overlayer lead to an effective reduction in overpotential, enhanced Faradaic efficiencies and current densities for H2O2 reduction to H2O. As a non-enzymatic amperometric sensor, the resulting ONPCNR/SWCNTs nanocomposite-modified electrode exhibited high sensitivity and selectivity for the detection of H2O2 in the range of 1.0–500 μM with a detection limit of 0.51 μM (S/N = 3). The results indicated that the synergetic effect with ONPCNRs improves the capability of the PDDA/SWCNTs matrix for H2O2 detection. This work demonstrated that ONPCNRs/SWCNTs nanocomposite possesses the feasibility and potential applications in sensing.
Pub.: 24 Feb '17, Pinned: 12 Apr '17
Abstract: Spontaneously charged aerosol droplets, each containing a few single-walled carbon nanotubes wrapped in conjugated polymers were precipitated on a target substrate using electrostatic forces. Nanotube networks were assembled on a variety of dielectric surfaces including polymers with low surface energy: Good transistor performance was achieved in all cases. Under proper regime of electrostatic and flow fields, patterns were produced in a maskless fashion and feature sizes below 150 μm were demonstrated.
Pub.: 17 Jan '17, Pinned: 12 Apr '17
Abstract: The aniline was polymerized onto functionalized multi-walled carbon nanotubes in order to obtain a cathode material with core-shell structures for lithium batteries. The structure and morphology of the samples were investigated by Fourier transform infrared spectroscopy analysis, scanning electron microscope, transmission electron microscope and X-ray diffraction. The electrochemical properties of the composite were characterized by the cyclic voltammetry, the charge/discharge property, coulombic efficiency, and ac impedance spectroscopy in detail. At a constant current density of 0.2 C, the first specific discharge capacity of the reduced and oxidized PANI/WMCNTs were 181.8 mAh/g and 135.1 mAh/g separately, and the capacity retention rates were corresponding to 76.75% and 86.04% for 100 cycles with 99% coulombic efficiency. It was confirmed that the CNTs obviously enhanced the conductivity and electrochemical performance of polyaniline, and compared with the pure PANI, the reduced composite possessed a quite good performance for the cathode of lithium batteries.
Pub.: 15 Dec '16, Pinned: 12 Apr '17
Abstract: Sensing capabilities of carbon nanotube (CNT) epoxy materials have been studied in order to develop multifunctional coatings for damage detection. For that purposes CNT doped epoxy nmixtures have been manufacturing using toroidal stirring. The microstructural characterization of CNT dispersion has been carried out by optical microscopy, showing the good homogenization effect induced by toroidal stirring. Then, electromechanical tests have been carried out on bulk nanocomposites and strain gauges. From tensile tests, it has been noticed that the Gauge Factor (GF) of strain gauges is much higher than those of bulk nanocomposites and conventional metallic gauges. Bending tests, which gauges made over tensile or compressive faces of the samples show that strain gauges have different behaviors while bulk materials show similar ones due to electrical volume interactions, proving the potential of strain gauges for monitoring complex load states. Damage sensing of CNT/epoxy materials has been also proved by inducing artificial defects on a monitored coating as changes in electrical resistance related to damage size. Thus damage detection, location and quantification have been achieved.
Pub.: 28 Mar '17, Pinned: 12 Apr '17