A gas sensor, fabricated by the simple casting of single-walled carbon nanotubes (SWNTs) on an interdigitated electrode (IDE), is presented for and organic vapor detection at room temperature. The sensor responses are linear concentrations sub ppm to hundreds with limits 44 ppb NO2 262 nitrotoluene. time order seconds response minutes recovery. variation sensitivity less than 6% all tested devices, comparable commercial metal oxide or polymer microfilm sensors while retaining...

We studied various gas molecules (NO2, O2, NH3, N2, CO2, CH4, H2O, H2, Ar) on single-walled carbon nanotubes (SWNTs) and bundles using first principles methods. The equilibrium position, adsorption energy, charge transfer, electronic band structures are obtained for different kinds of SWNTs. Most adsorb weakly SWNTs can be either donors or acceptors to the nanotubes. find that bundle interstitial groove sites is stronger than individual properties sensitive certain gases such as NO2 O2....

A nanoelectrode array based on vertically aligned multiwalled carbon nanotubes (MWNTs) embedded in SiO2 is used for ultrasensitive DNA detection. Characteristic electrochemical behaviors are observed measuring bulk and surface-immobilized redox species. Sensitivity dramatically improved by lowering the nanotube density. Oligonucleotide probes selectively functionalized to open ends of nanotubes. The hybridization subattomole targets can be detected combining such electrodes with Ru(bpy)32+...

Electronic structure of deformed carbon nanotubes varies widely depending on their chirality and deformation mode. We present a framework to analyze these variations by quantifying the dispersion relation density states. The theory is based Huckel tight-binding model confirmed four orbital simulations under stretching, compression, torsion, bending. It unriddles unifies previous band gap studies predicts shifting, merging, splitting Van Hove singularities in state, zigzag pattern change with...

We report a bottom-up approach to integrate multiwalled carbon nanotubes (MWNTs) into multilevel interconnects in silicon integrated-circuit manufacturing. MWNTs are grown vertically from patterned catalyst spots using plasma-enhanced chemical vapor deposition. demonstrate the capability grow aligned structures ranging single tube forest-like arrays at desired locations. SiO2 is deposited encapsulate each nanotube and substrate, followed by mechanical polishing process for planarization....

Composites of uniaxially oriented multiwalled carbon nanotubes embedded in polymer matrices were fabricated and investigated by transmission electron microscopy. In strained composite films, buckling was ubiquitously observed bent with large curvatures. By analyses a number nanotubes, the onset strain fracture estimated to be ≈5% ⩾18%, respectively. The wavelengths are proportional dimensions nanotubes. Examination surface showed adherence

Single-walled carbon nanotubes (CNTs) may enable the fabrication of integrated circuits smaller than 10 nanometers, but this would require scalable production dense and electronically pure semiconducting nanotube arrays on wafers. We developed a multiple dispersion sorting process that resulted in extremely high purity dimension-limited self-alignment (DLSA) procedure for preparing well-aligned CNT (within alignment 9 degrees) with tunable density 100 to 200 CNTs per micrometer 10-centimeter...

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We use a simple picture based on the $\ensuremath{\pi}$ electron approximation to study band-gap variation of carbon nanotubes with uniaxial and torsional strain. find (i) that magnitude slope band gap versus strain has an almost universal behavior depends chiral angle, (ii) sign value $(n\ensuremath{-}m)\mathrm{mod}3,$ (iii) novel change in arising from quantum number corresponding minimum gap. Four orbital calculations are also presented show results valid.

A vertically aligned carbon nanotube (CNT) array is fabricated as a nanoelectrode platform for biosensor development. Prior to chemical functionalization, metal catalyst particles at the ends of CNT are removed and closed opened. We find that oxidative treatment generating functional groups opened compromise mechanical stability nanotubes, often leading total collapse CNTs. To solve this problem, we have developed new approach filling gaps between CNTs with spin-on glass (SOG). Results from...

We studied Li-intercalated carbon nanotube ropes by first-principles methods. Results show charge transfer between Li and C small structural deformation due to intercalation. Both the interior of interstitial space are susceptible for The intercalation potential a single-walled rope is comparable that graphite almost independent density up around LiC2, as observed in recent experiments. This significantly higher than graphite, making nanorope promising candidate anode material battery applications.

We report on the electrochemical study of three carbon nanotube ensemble electrodes: single-walled paper, as-produced multiwalled towers, and heat-treated towers. Cyclic voltammetry was used in 0.10 M KCl containing 5.0 mM K4Fe(CN)6 to obtain information both capacitive background electron transfer rate from faradaic reaction redox species. The capacitance gives insight into effective surface area (including exterior interior within film) as well "pseudocapacitance" due reactions bonded...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTGlass Transition Temperatures of Polymers from Molecular Dynamics SimulationsJie Han, Richard H. Gee, and BoydCite this: Macromolecules 1994, 27, 26, 7781–7784Publication Date (Print):December 1, 1994Publication History Published online1 May 2002Published inissue 1 December 1994https://pubs.acs.org/doi/10.1021/ma00104a036https://doi.org/10.1021/ma00104a036research-articleACS PublicationsRequest reuse permissionsArticle...

ZnO nanowires have been synthesized using a catalyst-assisted heteroepitaxial carbothermal reduction approach on m-sapphire substrate. Intricate and uniform arrays obtained with each nanowire forming an angle ∼30° the substrate normal. Photoluminescence studies at room temperature for wavelengths between 335 620 nm reveal strong single exciton peak ∼380 (3.26 eV) accompanying deep-level blueshifted emission peaks ∼486, 490, 510 nm. UV resonant Raman spectroscopy has used to characterize...

We show that covalent sidewall functionalization of single-wall nanotubes leads to drastic changes nanotube electronic states near the Fermi level. The sp3 hybridization between functional group and induces an impurity state is found be extended over a large distance (>1 nm) even though structural deformation confined vicinity functionalizing site. Thus, dramatic in conductive properties can expected if concentration molecules small. This effect provides effective pathway for band structure...

The interaction between carbon nanotubes and organic molecules including benzene (C6H6), cyclohexane (C6H12), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ: C8N2O2Cl2) have been studied using first principles calculations. equilibrium tube-molecule distance, adsorption energy, charge transfer are obtained. hybridization the DDQ molecular level nanotube valence bands transforms semiconducting tube into a metallic one. Coupling of π electrons tubes aromatic observed. Our results show that...

We report a novel approach for the fabrication of nanoelectrode arrays using vertically aligned multi-walled carbon nanotubes (MWCNTs) embedded within SiO2 matrix. Cyclic voltammetry and pulse are employed to characterize electrochemical properties MWCNT array. The unique graphitic structure nanoelectrodes is compared with model systems such as highly oriented pyrolytic graphite glassy electrodes. Low-density display independent behavior showing diffusion-limited steady-state currents in...

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTDirected Growth of Free-StandingSingle-Walled Carbon NanotubesAlan M. Cassell, Nathan R. Franklin, Thomas W. Tombler, Emory Chan, Jie Han, and Hongjie DaiView Author Information Department Chemistry, Stanford University Stanford, California 94350 NASA Ames Research Center, M/S T27A-1 Moffett Field, 94035 Cite this: J. Am. Chem. Soc. 1999, 121, 34, 7975–7976Publication Date (Web):August 10, 1999Publication History Received21 June 1999Published...

This letter presents p-type metal–oxide–semiconductor (PMOS) and complementary (CMOS) inverters based on single-walled carbon nanotube field-effect transistors. The device structures consist of nanotubes grown via a chemical-vapor deposition method contacted by two metallic source/drain electrodes. Electrical properties both (without doping) n-type transistors with potassium doping have been measured. By utilizing resistor as the load for transistor, PMOS inverter is demonstrated....

Carbon nanotube tips are explored in fabricating oxide nanostructures on silicon surfaces with an atomic force microscope. Nanotubes can write at speeds up to 0.5 mm/s over large surface areas, and present a solution the long-standing tip-wear problem. Experimental theoretical work find that impervious high compressive lateral forces breakdown electric fields. A “cleaving” method is developed reproducibly obtain dome-closed multi-walled suitable length. Nanotube materials could become key...

A high density plasma from a methane–hydrogen mixture is generated in an inductively coupled reactor, and multiwalled carbon nanotubes (MWNTs) are grown on silicon substrates with multilayered Al/Fe catalysts. The vertically aligned, the alignment better than orientation commonly seen thermally samples. detailed parametric study varying inductive power, pressure, temperature, gas composition, catalyst thickness, power to substrate undertaken. Transmission electron microscopy Raman...

The work functions (WF's) of single-walled carbon nanotubes and bundles are studied using first-principles methods. For individual metallic tubes, the WF is independent chirality increase slightly with tube diameter. semiconducting (as defined by HOMO energy) decreases rapidly. nanotube $(\ensuremath{\sim}5 \mathrm{eV})$ shows no clear dependence on size chirality, higher than tubes. both nanotubes, dramatically upon alkali-metal intercalation. electronic states near Fermi level...

Solution-derived carbon nanotube (CNT) network films with high semiconducting purity are suitable materials for the wafer-scale fabrication of field-effect transistors (FETs) and integrated circuits (ICs). However, it is challenging to realize high-performance complementary metal-oxide semiconductor (CMOS) FETs yield stability on such CNT films, this difficulty hinders development CNT-film-based ICs. In work, we developed a doping-free process CMOS based solution-processed in which polarity...