Creating covalent bonds between Cu and C at the interface of metal/open-ended carbon nanotubes.

The unique electrical properties of carbon nanotubes (CNTs) are highly desired in many technological applications. Unfortunately, in practice, the electrical conductivity of most CNTs and their assemblies has fallen short of expectations. One reason for this poor performance is that electrical resistance develops at the interface between carbon nanomaterials and metal surfaces when traditional metal-metal type contacts are employed.

Evaluation of Polymer-Coated Carbon Nanotube Flexible Microelectrodes for Biomedical Applications.

The demand for electrically insulated microwires and microfibers in biomedical applications is rapidly increasing. Polymer protective coatings with high electrical resistivity, good chemical resistance, and a long shelf-life are critical to ensure continuous device operation during chronic applications. As soft and flexible electrodes can minimize mechanical mismatch between tissues and electronics, designs based on flexible conductive microfibers, such as carbon nanotube (CNT) fibers, and soft polymer insulation have been proposed.

Reagentless Dissolution and Quantification of Particulate Lead in Tap Water via Membrane Electrolysis.

The presence of particulate Pb in tap water has been a limiting factor in the design of accurate and portable platforms for quantifying this toxic metal. Convenient and affordable electrochemical techniques are blind toward particulate species and thus require addition of reagents and additional chemical processing such as sample acidification. This study describes the fundamentals and the first use of membrane electrolysis for the reagentless sample preparation of tap water for the detection of particulate Pb contaminants.

Impact of physical and chemical parameters on square wave anodic stripping voltammetry for trace Pb detection in water.

Exposure to lead, a toxic heavy metal, in drinking water is a worldwide problem. Lead leaching from lead service lines, the main contamination source, and other plumbing materials is controlled by the plumbosolvency of water. Square wave anodic stripping voltammetry (SWASV) has been greatly explored as a rapid and portable technique for the detection of trace Pb ions in drinking water.

Hydrophilic Micro- and Macroelectrodes with Antibiofouling Properties for Biomedical Applications.

Implantable neural electrodes are generally used to record the electrical activity of neurons and to stimulate neurons in the nervous system. Biofouling triggered by inflammatory responses can dramatically affect the performance of neural electrodes, resulting in decreased signal sensitivity and consistency over time. Thus, long-term clinical applications require electrically conducting electrode materials with reduced dimensions, high flexibility, and antibiofouling properties that can reduce the degree of inflammatory reactions and increase the lifetime of neural electrodes.

Near-electrode pH change for voltammetric detection of insoluble lead carbonate.

Lead contamination of drinking water is a concern to all inhabitants of old cities where lead pipes and soldering are still present. Simple on-site electrochemical detection methods are promising technologies that have gained attention recently. However, conventional electrochemical techniques only quantify soluble forms of lead in water without accounting for insoluble particulates.

Functionalized carbon nanotube microfibers for chronic neural implants.

Background: Much progress has been made at the interface between neural tissue and electrodes for neurophysiology. However, there continues to be a need for novel materials that integrate well with the nervous system and facilitate neural recordings with longer-term sustainability and stability. Such materials have the potential to improve clinical approaches and provide important tools for basic neuroscience research.

Carbon Nanotube Microelectrode Set: Detection of Biomolecules to Heavy Metals.

An ultrasensitive electrochemical microelectrode set (μ-ES), where all three electrodes are made of highly densified carbon nanotube fiber (HD-CNTf) cross sections (length ∼40 μm), embedded in an inert polymer matrix, and exposed open-ended CNTs at the interface, is presented here. Bare open ends of HD-CNTf rods were used as the working (∼40 μm diameter) and counter (∼94 μm diameter) electrodes, while the cross section of a ∼94 μm diameter was electroplated with Ag/AgCl and coated with Nafion to employ as a quasi-reference electrode. The Ag/AgCl/Nafion-coated HD-CNTf rod quasi-reference electrode provided a very stable potential comparable to the commercial porous-junction Ag/AgCl reference electrode.

Hydrogen Nanometrology in Advanced Carbon Nanomaterial Electrodes.

A comparative experimental study between advanced carbon nanostructured electrodes, in similar hydrogen uptake/desorption conditions, is investigated making use of the recent molecular beam-thermal desorption spectrometry. This technique is used for monitoring hydrogen uptake and release from different carbon electrocatalysts: 3D-graphene, single-walled carbon nanotube networks, multi-walled carbon nanotube networks, and carbon nanotube thread. It allows an accurate determination of the hydrogen mass absorbed in electrodes made from these materials, with significant enhancement in the signal-to-noise ratio for trace hydrogen avoiding recourse to ultra-high vacuum procedures.

Parts per trillion detection of heavy metals in as-is tap water using carbon nanotube microelectrodes.

Heavy metal contamination of drinking water is a major global issue. Research reports across the globe show contamination of heavy metals higher than the set standards of the World Health Organization (WHO) and US Environmental Protection Agency (EPA). To our knowledge, no electrochemical sensor for heavy metals with parts per trillion (PPT) limits of detection (LOD) in as-is tap water has been reported or developed.

True Picomolar Neurotransmitter Sensor Based on Open-Ended Carbon Nanotubes.

Neurotransmitters are important chemicals in human physiological systems for initiating neuronal signaling pathways and in various critical health illnesses. However, concentration of neurotransmitters in the human body is very low (nM or pM level) and it is extremely difficult to detect the fluctuation of their concentrations in patients using existing electrochemical biosensors. In this work, we report the performance of highly densified carbon nanotubes fiber (HD-CNT) cross-sections called rods (diameter ∼ 69 μm, and length ∼ 40 μm) as an ultrasensitive platform for detection of common neurotransmitters.

Defect Sites Modulate Fouling Resistance on Carbon-Nanotube Fiber Electrodes.

Carbon nanotube (CNT) fiber electrodes have become increasingly popular electrode materials for neurotransmitter detection with fast-scan cyclic voltammetry (FSCV). The unique properties of CNT fiber electrodes like increased electron transfer, sensitivity, waveform application frequency independence, and resistance to fouling make them ideal biological sensors for FSCV. In particular, their resistance to fouling has been observed for several years, but the specific physical properties which aid in fouling resistance have been debated.

Heatable carbon nanotube composite membranes for sustainable recovery from biofouling.

Membrane filtration is one of the most reliable methods for water treatment. However, wider application is limited due to biofouling caused by accumulation of microorganisms on the membrane surface. This report details a heatable carbon nanotube composite membrane with self-cleaning properties for sustainable recovery from biofouling.

Carbon Nanotube Fiber Ionization Mass Spectrometry: A Fundamental Study of a Multi-Walled Carbon Nanotube Functionalized Corona Discharge Pin for Polycyclic Aromatic Hydrocarbons Analysis.

Mass spectrometry continues to tackle many complicated tasks, and ongoing research seeks to simplify its instrumentation as well as sampling. The desorption electrospray ionization (DESI) source was the first ambient ionization source to function without extensive gas requirements and chromatography. Electrospray techniques generally have low efficiency for ionization of nonpolar analytes and some researchers have resorted to methods such as direct analysis in real time (DART) or desorption atmospheric pressure chemical ionization (DAPCI) for their analysis.

Carbon Nanotube Thread Electrochemical Cell: Detection of Heavy Metals.

In this work, all three electrodes in an electrochemical cell were fabricated based on carbon nanotube (CNT) thread. CNT thread partially insulated with a thin polystyrene coating to define the microelectrode area was used as the working electrode; bare CNT thread was used as the auxiliary electrode; and a micro quasi-reference electrode was fabricated by electroplating CNT thread with Ag and then anodizing it in chloride solution to form a layer of AgCl. The Ag|AgCl coated CNT thread electrode provided a stable potential comparable to the conventional liquid-junction type Ag|AgCl reference electrode.

Flexible Micro-Supercapacitor Based on Graphene with 3D Structure.

Flexible micro-supercapacitors (MSCs) are constructed by 3D graphene from chemical vapor deposition. Without using any binder or metal current collector, the as-prepared 3D graphene MSC exhibits good flexibility, excellent cyclic life, and high areal capacitance of 1.5 mF cm at a scan rate of 10 V s .

Mechanical Strength Improvements of Carbon Nanotube Threads through Epoxy Cross-Linking.

Individual Carbon Nanotubes (CNTs) have a great mechanical strength that needs to be transferred into macroscopic fiber assemblies. One approach to improve the mechanical strength of the CNT assemblies is by creating covalent bonding among their individual CNT building blocks. Chemical cross-linking of multiwall CNTs (MWCNTs) within the fiber has significantly improved the strength of MWCNT thread.

Optically transparent carbon nanotube film electrode for thin layer spectroelectrochemistry.

Carbon nanotube (CNT) film was evaluated as an optically transparent electrode (OTE) for thin layer spectroelectrochemistry. Chemically inert CNT arrays were synthesized by chemical vapor deposition (CVD) using thin films of Fe and Co as catalysts. Vertically aligned CNT arrays were drawn onto a quartz slide to form CNT films that constituted the OTE.

Free-standing carbon nanotube-titania photoactive sheets.

We report on the development of a new photoactive material via titania (TiO2) nanoparticle deposition on free-standing aligned carbon nanotube (CNT) sheets. Controlling homogeneous dispersion of negatively charged TiO2 nanoparticles, achieved by adjusting pH higher than the point of zero charge (PZC), influenced electrochemical deposition of TiO2 on CNT sheets substrate. Varying deposition time with constant voltage, 5 V allowed different thickness of TiO2 to be deposited layer on the CNT sheets.

Polymer Coating of Carbon Nanotube Fibers for Electric Microcables.

Carbon nanotubes (CNTs) are considered the most promising candidates to replace Cu and Al in a large number of electrical, mechanical and thermal applications. Although most CNT industrial applications require macro and micro size CNT fiber assemblies, several techniques to make conducting CNT fibers, threads, yarns and ropes have been reported to this day, and improvement of their electrical and mechanical conductivity continues. Some electrical applications of these CNT conducting fibers require an insulating layer for electrical insulation and protection against mechanical tearing.

Wet catalyst-support films for production of vertically aligned carbon nanotubes.

A procedure for vertically aligned carbon nanotube (VA-CNT) production has been developed through liquid-phase deposition of alumoxanes (aluminum oxide hydroxides, boehmite) as a catalyst support. Through a simple spin-coating of alumoxane nanoparticles, uniform centimer-square thin film surfaces were coated and used as supports for subsequent deposition of metal catalyst. Uniform VA-CNTs are observed to grow from this film following deposition of both conventional evaporated Fe catalyst, as well as premade Fe nanoparticles drop-dried from the liquid phase.

Dendrimer-assisted self-assembled monolayer of iron nanoparticles for vertical array carbon nanotube growth.

Self-assembled monolayers (SAMs) of iron oxide nanoparticles have been prepared using carboxylic-acid-terminated dendrimers. The iron-containing SAM was used as the catalyst for growth of vertical arrays of carbon nanotubes (CNTs). This approach has the potential for producing diameter controlled CNTs from premade catalyst nanoparticles as well as large scale production of CNTs by chemical vapor deposition.

Dry contact transfer printing of aligned carbon nanotube patterns and characterization of their optical properties for diameter distribution and alignment.

A scalable and facile approach is demonstrated where as-grown patterns of well-aligned structures composed of single-walled carbon nanotubes (SWNT) synthesized via water-assisted chemical vapor deposition (CVD) can be transferred, or printed, to any host surface in a single dry, room-temperature step using the growth substrate as a stamp. We demonstrate compatibility of this process with multiple transfers for large-scale device and specifically tailored pattern fabrication. Utilizing this transfer approach, anisotropic optical properties of the SWNT films are probed via polarized absorption, Raman, and photoluminescence spectroscopies.

Abrasion as a catalyst deposition technique for carbon nanotube growth.

Mechanical abrasion of stainless steel (SS) surfaces is demonstrated as an effective technique for the deposition of catalyst to support growth of high density layers of carbon nanotubes (CNTs) in water-assisted catalytic chemical vapor deposition. In all cases of Fe-containing materials abraded on Al(2)O(3) substrates, CNT growth is observed; the 400 series of SS appears to deposit catalyst most efficiently. We demonstrate that this simple abrasion technique enables both micro- and nanoscale accuracy in catalyst patterning as well as large area catalyst deposition for uniform, dense CNT growth.