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Field emission devices using a wet-processed composite cathode of carbon nanotube films coated with titanium dioxide exhibit outstanding field emission characteristics, including ultralow turn on field of 0.383 V μm-1 and threshold field of 0.657 V μm-1 corresponding with a very high field enhancement factor of 20000, exceptional current stability, and excellent emission uniformity. The improved field emission properties are attributed to the enhanced edge effect simultaneously with the reduced screening effect, and the lowered work function of the composite cathode. In addition, the highly stable electron emission is found due to the presence of titanium dioxide nanoparticles on the carbon nanotubes, which prohibits the cathode from the influence of ions and free radical created in the emission process as well as residual oxygen gas in the device. The high-performance solution-processed composite cathode demonstrates great potential application in vacuum electronic devices. [ABSTRACT FROM AUTHOR]

Low cost and large scale carbon nanotube and nanofibre (CNT-CNF) composite films have been fabricated and employed as electrodes for electrosorption of cupric ions. The regeneration of the saturated CNT-CNF film electrode has been investigated. Three methods (short-circuiting, short-circuiting and then reversing voltage, reversing voltage and then short-circuiting) are used for regeneration. The results show that low regeneration efficiency of CNT-CNF film electrode due to electrodeposition of Cu on the electrode surface can be highly improved by regeneration applying reverse voltage combined with short circuit. 93% regeneration efficiency can be achieved when 0.8 V reverse voltage is applied before short-circuiting during regeneration of CNT-CNF film electrode. [ABSTRACT FROM AUTHOR]

Carbon nanotubes and nanofibres (CNTs-CNFs) films have been grown on Ni sheets by low pressure chemical vapor deposition system and show good physical adsorption capability for ferric (Fe3+) ions. The studies of adsorption kinetics and isotherms indicate that Fe3+ adsorption process was regarded as first-order model and followed a Langmuir isotherm indicating monolayer adsorption. The saturated CNTs-CNFs film is easy to be regenerated by electrodesorption with direct voltage applied. The result shows that the combination of adsorption and electrodesorption by CNTs-CNFs is a promising technology to remove the Fe3+ contamination in solution, which can be further extended to the process of other heavy metal ions. [ABSTRACT FROM AUTHOR]

In addition to Ni, Co, and Fe, the authors show that a copper (Cu) chromium (Cr) alloy can be a good catalyst for controlled growth of carbon nanotubes (CNTs). A thermal chemical vapor deposition was used at 600 °C to deposit the CNTs, and a dual-target magnetron sputtering system was used to control the ratio of the Cu/Cr alloy. The material properties of the CNTs, such as concentration, diameter, and density, are directly affected by the ratio of Cu/Cr alloy, which subsequently affect the field-emission properties. Their results showed that Cr can be used to effectively control the catalytic effects of the Cu catalysts, where the quality of the CNTs could vary while the density could be controlled from 4×107 to 5×1010 tubes/cm2. The field-emission current density of the CNT film increases with Cu/Cr ratio from 1/6.4 to 4.6/1 and decreases when the Cu/Cr ratio is more than 4.8/1 in the alloy film. When the Cu/Cr ratio is at 4.6/1, the average current density peaks at 5129 μA/cm2 at the applied field of 3.53 V/μm, showing an optimized field-emission property. [ABSTRACT FROM AUTHOR]

Growth of carbon nanotube (CNT) films with good field emission properties on glass is very important for low cost field emission display (FED) applications. In addition to Ni, Co and Fe, Cu can be a good catalyst for CNT growth on glass, but due to diffusion into SiO2 it is difficult to control the CNTs density and uniformity. In this paper, four metal barrier layers (W, Ni, Cr, Ti) were deposited by dc magnetron sputtering on glass to reduce the Cu diffusion. As-grown CNT films showed various morphologies with the use of different barrier metals. CNTs with uniform distribution and better crystallinity can be synthesized only on Ti/Cu and W/Cu. Voltage current measurements indicate that better field emission properties of CNT films can be obtained on titanium and tungsten barriered Cu, while chromium and nickel are not suitable barrier candidates for copper in CNT-FED applications because of the reduced emission performance. [ABSTRACT FROM AUTHOR]

In this paper, hybrid transparent conductive films (TCFs) are designed by combining silver nanowires with the single-wall carbon nanotubes (SWCNTs) and the transparent heating films (THFs) based on the TCFs are evaluated for possible vehicle applications. By comparing the properties, including the transmittance, sheet resistance, microstructure and heating curves, we found that the SWCNTs/AgNWs are considerably suitable for making THFs. The after-treatment methods, such as physical method (hot roll pressing) and chemical method (nitric acid and Poly (diallydimethylammonium chloride) solution, (PDAC)) were researched in detail to optimize the sheet resistance and transparency to fit the THF requirements. A careful study of the different after-treatment methods revealed that hot roll pressing can quickly and efficiently improve the properties, while the nitric acid is more helpful than PDAC for the long-term stability. The results showed that a small amount of SWCNTs addition can promote the endurable maximum electric current by spreading the heat fast and efficiently, and the maximum current flow can be as high as 4 A. The thermal stability of the THFs and the de-frog performance were tested, indicating that the hybrid film had an advantage in resisting current shock and good thermal efficiency was obtained. The fabricated TCFs of stable thermal properties are qualified as a windshield-glass heater. [ABSTRACT FROM AUTHOR]

The carbon nanotube and carbon nanofibre (CNT--CNF) composite films are synthesized on different graphite substrate by low-pressure and low-temperature chemical vapor deposition. Scanning electron microscopy measurement and N2 adsorption experiment show that CNT--CNF composite films have network structure with optimal pore size distribution, which is beneficial to capacitive deionization. Atomic force microscopy result indicates that there is a strong correlation between the surface roughness of graphite and their thickness. Furthermore, the electrosorptive performance in salt solutions by employing as-grown CNT--CNF composite film is studied and found that the properties of the graphite substrate play a vital role in electrosorptive performance of CNT--CNF composite films by influencing their network structures. [ABSTRACT FROM AUTHOR]

The kinetics, thermodynamics, and isotherms during electrical removal of Cu2+ by carbon nanotube and carbon nanofiber (CNTCNF) electrodes in CuCl2 solution were studied under different solution temperatures, initial Cu2+ concentrations, and applied voltages. The result shows that Langmuir isotherm can describe experimental data well, indicating monolayer adsorption, and higher Cu2+ removal and rate constant are achieved at higher voltage, lower initial Cu2+ concentration, and higher solution temperature. Meanwhile, the thermodynamics analyses indicate that the electrical removal of Cu2+ onto CNT-CNF electrodes is mainly driven by a physisorption process. [ABSTRACT FROM AUTHOR]