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Graphene oxide (GO), reduced graphene oxide (rGO) and carbon nanotubes (CNTs) have their own advantages in electrical, optical, thermal and mechanical properties. An effective combination of these materials is ideal for preparing transparent conductive films to replace the traditional indium tin oxide films. At present, the preparation conditions of rGO are usually harsh and some of them have toxic effects. In this paper, an SnCl2/ethanol solution was selected as the reductant because it requires mild reaction conditions and no harmful products are produced. The whole process of rGO preparation was convenient, fast and environmentally friendly. Then, SEM, XPS, Raman, and XRD were used to verify the high reduction efficiency. CNTs were introduced to improve the film conductive property. The transmittance and sheet resistance were the criteria used to choose the reduction time and the content ratios of GO/CNT. Thanks to the post-treatment of nitric acid, not only the by-product (SnO2) and dispersant in the film are removed, but also the doping effect occurs, which are all conducive to reducing the sheet resistances of films. Ultimately, by combining rGO, GO and CNTs, transparent conductive films with a bilayer and three-dimensional structure were prepared, and they exhibited high transmittance and low sheet resistance (58.8 Ω/sq. at 83.45 T%, 47.5 Ω/sq. at 79.07 T%), with corresponding $${{\sigma_{dc} } \mathord{\left/ {\vphantom {{\sigma_{dc} } {\sigma_{opt} }}} \right. \kern-\nulldelimiterspace} {\sigma_{opt} }}$$ σ dc / σ opt values of 33.8 and 31.8, respectively. In addition, GO and rGO can modify the surface and reduce the film surface roughness. The transparent conductive films are expected to be used in photoelectric devices.

Herein, we demonstrated for the first time the green fabrication of graphene by wet ball milling method which utilizes natural honey as exfoliation medium, further the 3D conductive networks (Graphene/Carbon nanotubes/PEDOT:PSS, G/CNT/PEDOT:PSS) were integrated into the biodegradable Starch/Chitosan/Poly vinyl alcohol (S/C/PVA) substrates. This electrode possesses an excellent optoelectronic performance (Rs = 43.2 Ω/sq., T = ca. 80% at 550 nm), and a very low Root Mean Square (RMS) roughness (approximately 1.38 nm). The sheet resistance of the films changed slightly after 1000 bending cycles and adhesion tests. The flexible green light OLED using G/CNT/PEDOT:PSS-S/C/PVA film as anode was successfully fabricated, the luminance of the device was 5701 cd/m2 at 15 V and the maximum current efficiency was 3.75 cd/A at 13 V. Moreover, this new type of OLED device degrades gradually within 10 min in 2 wt% lysozyme CH3COOH solution, which could be used to prepare the next generation of user-friendly, eco-friendly flexible wearable electronic devices.

Carbon nanotubes (CNTs) and graphene oxide (GO) were sprayed on flexible polyethylene terephthalate (PET) substrates to prepare CNT and GO–CNT transparent conductive films (TCFs). For the GO–CNT TCFs, when the mass ratio of GO to CNTs was 0.2, a relatively low sheet resistance of 90.4 Ω sq−1 at a transmittance of 87% (550 nm) was obtained with an average σdc/σopt value of 28.9. Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) solution without or with ethylene glycol (EG) added was sprayed on the surface of the GO–CNT films to obtain P/GO–CNT and P(E)/GO–CNT films, respectively. P(E)/GO–CNT films were post-treated with sulfuric acid to obtain P(E,S)/GO–CNT TCFs. The addition of PEDOT:PSS can permeate into the pores of networks and densify the GO–CNT networks, increasing the conductivity and wettability and decreasing the roughness of the films. Additional EG can reduce the Coulomb force between PEDOT and PSS and change the morphology of PEDOT, and at the same time sulfuric acid treatment can effectively remove PSS from the PEDOT:PSS layer. The P(E,S)/GO–CNT 0.2 TCFs exhibited a sheet resistance of 46.3 Ω sq−1 at a transmittance of 87.5% (550 nm) with an average σdc/σopt value of 56.1. The organic light emitting diodes were successfully fabricated, and the mechanism of how the electrical conductivity of the hybrid film increased was also investigated.

Carbon nanotubes (CNTs) and poly(3,4-ethylenedioxythiophene):poly (styrene sulfonate) (PEDOT:PSS) were employed to prepare sandwich-structured CNT/PEDOT:PSS/CNT transparent conductive films (TCFs) on flexible polyethylene terephthalate (PET) substrate by a spraying method. Based on the film morphology, we suggest that the CNTs were embedded in PEDOT:PSS. The structured film was more stable and did not peel off during post-processing nitric acid treatment. Ethylene glycol (EG) was used to improve the conductivity of the film, and the best ratio of PEDOT:PSS to EG was 10:5. XPS and Raman spectroscopy studies revealed that the non-conductive sodium dodecylbenzene sulfonate and PSS were removed during the nitric acid treatment. TCF sheet resistance as low as 95.15 Ω/sq at 87.72% transmittance (at a wavelength of 550 nm) was obtained. When the CNT/PEDOT:PSS/CNT-TCF was used as an anode in an organic light emitting diode, the high luminance of the device was 1598 cd/cm2 at 14 V, and the maximum current efficiency was 1.5 cd/A at 13 V.

Transparent conductive films (TCFs) were fabricated via a spray-coating method with a solution prepared by dispersing single-walled carbon nanotubes (SWCNTs) in deionized water with sodium dodecylbenzene sulfonate (SDBS) as surfactant. We explored the mechanism of HNO3 treatment by treating TCFs with different reagents. After being treated with different concentrations of reagents by HNO3, HCl, and NaNO3 to lower the sheet resistance of TCFs, the properties of TCFs were further characterized by a UV-VIS spectrophotometer, a four-point probe method, atom force microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. In this study, we conclude that the HNO3 treatment results in a decrease in the sheet resistance of the TCFs due to the combined effect of acidity and oxidizability. The strong interaction of the strong acidity and strong oxidizing property of HNO3 causes the SDBS to be removed. To further improve the film conductivity of the TCFs, the experimental conditions of the HNO3 treatment were optimized.

In this paper, the eco-friendly plant polyphenol, tannic acid (TA) was demonstrated as a non-covalent modifier for carbon nanotubes (CNTs), as well as a stripping medium to achieve exfoliated graphite to graphene by microfluidization. High-performance transparent flexible heater (TFH) with an embedded structure had been successfully fabricated by integrating conductive nanocomposites (TA-functionalized grapheme/TA-functionalized CNT/PEDOT:PSS; TG/TCNT/PEDOT) into waterborne polyurethane (WPU) film. Such a film exhibited favorable optical transmittance and sheet resistance (T = ca. 80% at 550 nm, Rs = 62.5 Ω/sq.), low root mean square (rms) roughness (approximately 0.37 nm), excellent adhesion and mechanical stability (the sheet resistance remained almost constant after 1000 bending cycle test for the bending radius of 10 mm), which are ideal as transparent heaters with high thermal efficiency. For TG/TCNT/PEDOT-WPU TFHs, the temperature increased rapidly and reached a steady state within 20 s with the maximum temperature reached to 116 °C, when the applied voltage was 20 V. Moreover, no variation in temperature was observed after the repeated heating–cooling tests and long-time stability test, indicating that TG/TCNT/PEDOT-WPU TCFs can be used as high performance TFHs. These TFH’s are expected to be suitable for vehicle defrosting, smart windows, portable heating, smart wearable devices, etc.

Membrane fouling limits membrane performance and membrane applications. Changing the membrane surface properties may effectively alleviate membrane fouling. Preparing conductive membranes is an efficient way to achieve this goal. In this paper, the polypyrrole–carbon nanotube/polyethersulfone composite membranes (PPy–CNT/PES) were successfully fabricated via a process of chemical polymerization of pyrrole on the CNT/PES substrate. The resistivity, pure water flux, as well as the fouling prevention performance of the PPy–CNT/PES membrane were systematically studied. The electric resistance of the PPy–CNT/PES membrane was greatly reduced to 450 ± 40 Ω cm-1, and the pure water flux for the PPy–CNT/PES membrane was about 136.2 ± 5.1 L m− 2 h− 1 bar− 1. The flux recovery rate of the PPy–CNT/PES membrane was increased from 68.18 to 76.38% compared with the pristine PES membrane. An electric field of 1 V/cm was applied between the titanium sheet and the PPy–CNT/PES membrane as a cathode, and the flux recovery rate of the PPy–CNT/PES membrane was improved to 81.78%. Therefore, the membrane cathode could effectively prevent the pore clogging, meaning that the prepared PPy–CNT/PES membrane has significant potential for practical applications in anti-fouling.

Improved OLED systems have great potential for next-generation display applications. Carbon nanotubes (CNTs) and the conductive polymers poly (3,4-ethylenedioxythiophene): poly (styrene sulfonate) (PEDOT: PSS) have attracted great interest for advanced applications, such as optoelectronic products. In this paper, the simultaneous enhancement of the conductivity, roughness, and adhesion properties of transparent conductive films with PEDOT: PSS/CNTs is reported. These films prepared by a simple spin-coating process were successfully used to produce high-performance organic light-emitting diodes (OLEDs) with an improved lifetime. Addition of PEDOT: PSS lowered the film sheet resistance and CNTs helped to enhance the stability and maintain the lifetime of the OLEDs. In addition, treatment with methanol and nitric acid changed the morphology of the polymer film, which led to greatly reduced sheet resistance, enhanced substrate adhesion, and reduced film roughness. The best performance of the film (PEDOT: PSS: CNT = 110: 1, W/W) was 100.34 Ω/sq.@ 90.1 T%. High transmittance, low sheet resistance, excellent adhesion, and low roughness (3.11 nm) were achieved synchronously. The fabricated OLED demonstrated a low minimum operating voltage (3 V) and could endure high voltage (20 V), at which its luminance reached 2973 cd/m2. Thus, the incorporation of CNTs within PEDOT: PSS electrodes has great potential for the improvement of the performance of OLED devices.

Carbon nanotubes (CNTs) and graphene (Gr) are promising materials for flexible transparent conductive films (TCFs) in optoelectronic application because of their exceptional electrical, optical, and mechanical properties. Here, high-quality graphene nanosheets were synthesized by the one-step green method which using natural polyphenols-gallic acid (GA) as the exfoliation medium through high-pressure homogenization; besides, GA molecules can also be used as a non-covalent modifier to obtain GA modified CNTs (GCNTs). Then, the Au decorated Gr/GCNT-PET (Au-Gr/GCNT-PET) TCFs were obtained by a simple spray-coating process. The TCFs exhibited an excellent optoelectronic performance (Rs = 45.6 Ω/sq., T = ca. 80% at 550 nm), relatively flat surface (roughness = 12.43 nm), good bending resistance (the ΔR Au-Gr/GCNT-PET TCF/R0 was 0.07 after 1000 times bending tests) and strong adhesion (the fT of all Au-Gr/GCNT PET films was higher than 0.8). Finally, the Au-Gr/GCNT-PET films were used as an anode to prepare flexible green-light OLED devices; the maximum luminance of the Au-Gr/GCNT-PET device was 6554.1 cd/m2 at 15V, and the maximum current efficiency was 4.03 cd/A. It confirmed that this type of TCFs has considerable potential application in photovoltaic devices.

Flexible transparent conducting films (TCFs) with carbon nanotubes (CNTs) have attracted more and more attention for their wide range of potential applications. While, there are still some problems to be solved on several aspects. In this study, a graphene oxide/carbon nanotube (GO/CNT) hybrid TCF was fabricated through the simple spray coating method. GO sheets were introduced to form new electron transporting channels. It was found that the best optoelectronic property films were fabricated when the ratio of GO/CNT is 1.5:1.0, which the sheet resistance of the film was found to be 146 Ω/sq at the transmittance of 86.0%. Due to the two-dimensional structure and the oxidation groups of GO sheets, flatness and wettability of the electrode surface was improved obviously. Adhesion factor of the TCFs was calculated by the change of transparent and sheet resistance after trial test, the addition of GO sheets enhanced the adhesion dramatically and the mechanism was analyzed. Improvements of conductivity, flatness, wettability and adhesion above are all advantageous for the solution-based processing of organic electronics for spraying and printing.

Antistatic technology has been applied in all aspects of modern life, including the manufacture of electronic products, aerospace systems, daily necessities and so on. The main purpose of this study is to obtain, using the Mayer rod-coating method, a flexible antistatic film with high transmittance, low sheet resistance and strong adhesion. With the help of the dispersant, single-walled carbon nanotubes (SWCNTs) were dispersed in water to form an homogeneous dispersion. The SWCNT dispersion was coated onto a poly(ethylene terephthalate) (PET) film with use of a rod to produce a uniform film. The antistatic films obtained had special characteristics, such as high transparency, low sheet resistance and excellent resistance to water and heat. Sheet resistance varied between 102–105 Ω sq−1 by controlling the content of water-based polyurethane (WPU), changing the thickness of the films and the post-treatment. The best film had a sheet resistance of 423 Ω sq−1 with 82.7% transmittance. In particular, the addition of the WPU binder greatly improved the adhesion between the CNTs and the PET film. Scanning electron microscopy, energy dispersive X-ray spectroscopy and Scotch™ tape method were conducted to determine the microstructure, cleanliness, and adhesion of the film, respectively.

Membrane fouling can be effectively addressed by modifying the membrane to realize anti-fouling capability together with real-time fouling detection. Here, we present the synthesis and water treatment testing of a promising candidate for this application, a composite membrane of polyvinylidene fluoride (PVDF) and functionalized carbon nano-materials prepared by a facile phase inversion method. The synergistic effect of oxidized multi-walled carbon nanotubes (OMWCNTs) and graphene oxide (GO) enabled better surface pore structures, higher surface roughness, hydrophilicity, and better antifouling property as compared with that of pristine PVDF membranes. The PVDF/OMWCNT/GO mixed matrix membranes (MMMs) achieved a high water flux of 125.6 L m−2 h−1 with high pollutant rejection rate, and their electrical conductivity of 2.11 × 10−4 S cm−1 at 100 kHz was sensitive to the amount of pollutant uptake. By using hybrid MMMs, we demonstrate simultaneous pollutant filtering and uptake monitoring, which is an important step in revolutionizing the water treatment industry.

In this paper, we used tannic acid (TA) functionalized carbon nanotubes (TCNTs), and silver nanowires (AgNWs) to construct a new type of transparent conductive film (TCF) with a double-layered conductive network structure. The hybrid film exhibits excellent light transmittance, high electrical conductivity, ultra-flexibility, and strong adhesion. These outstanding performances benefit from the filling and adhesion of hydrophilic TCNT layers to the AgNW networks. Besides, we introduced the post-treatment process of mechanical pressing and covering polymer conductive polymer PEDOT:PSS, which obtained three layers of TCNT/AgNW/PEDOT hybrid film and greatly improved the comprehensive properties. The hybrid film can reach a sheet resistance of 9.2 Ω sq−1 with a transmittance of 83.4% at 550 nm wavelength, and a low root mean square (RMS) roughness (approximately 3.8 nm). After 10 000 bends and tape testing, the conductivity and transmittance of the hybrid film remain stable. The resistance of the film has no significant degradation after 14 d of exposure to high temperature of 85 °C and humidity of 85%, indicating excellent stability. The organic light-emitting diodes (OLEDs) with TCNT/AgNW/PEDOT hybrid film as anode exhibit high current density and luminosity, confirming this process has considerable potential application in photovoltaic devices.

Preparing carbon nanotube (CNT) arrays by plasma enhanced chemical vapor deposition (PECVD) method can dramatically reduce the deposition temperature, which makes it possible for in-situ fabrication of CNT-based nanoelectronic devices. In this paper, up to date research progress of CNT arrays prepared by PECVD method was presented, including radio frequency PECVD, direct current PECVD and microwave PECVD. Then, morphology and quality of CNT arrays were compared. In the end, we analyzed the possible challenges encountered through CNT array preparation by PECVD method at the moment and in the future.

High purified single-walled carbon nanotubes (SWCNTs) were dispersed in water and transparent conducting films (TCFs) were fabricated by a spray coating. The produced uniform SWCNT–TCFs treated by nitric acid have a relatively low sheet resistance and high transmittance. The current–voltage (I–V) behaviors of the TCFs were measured at room to higher temperature during the heating or cooling process. It was found that the I–V behavior of TCFs strongly dependent on the temperature and applied voltage. The sheet resistance showed semiconductor behavior at low temperature and low voltage, while it showed metallic behavior at high temperature and high voltage.

Organic films and coatings, specifically those incorporating graphene oxide, offer many advantages as corrosion barriers due to the excellent shielding and tailorable characteristics of graphene oxide. A simple method was used to prepare a composite coating with polyurethane (PU) as a polymer matrix; gallic acid modified graphene oxide (FGO) flakes and acidified multi-walled carbon nanotubes (FMWCNTs) acted as nanoscale reinforcement. The presence of FMWCNTs improved the dispersion of FGO in PU, and the composite coating exhibited nearly no defects. The one-dimensional FMWCNTs and two-dimensional graphene oxide sheets attract each other to form a relatively stable layered structure, such that the graphene oxide sheets form a large shielding layer. The anticorrosion properties of the pristine PU and composite coatings were investigated by electrochemical impedance spectroscopy tests for 96 h. The composite coating reinforced by two carbon nanomaterials simultaneously underwent no corrosion after immersion for 96 h, and the corrosion resistance was better than that of the other coatings. The enhanced anticorrosion properties of the FMWCNT-FGO/PU composite coating are attributed to the fully exploited reinforcement effect from the network of FGO and FMWCNTs that is enabled via enhanced dispersion.

High-performance, flexible film heaters with carbon nanotube transparent conducting films are easily fabricated by both a rod-coating method and a spraying method. The main conclusion we have reached is that the film demonstrates a heating rate of 6.1°C s −1 at 35 V and sheet resistance as low as 94.7 Ω sq −1 with 72.04% optical transmittance at a wavelength of 550 nm by the spraying method after a series of post-treatment processes with acid and distilled water. Then, we adopt a mathematical method of nonlinear fitting to simulate the collected experimental data and the functions effectively. Furthermore, through analysis of the formula, the correlation between temperature and time is well explained. Therefore, carbon nanotube-based, flexible, transparent heaters exhibit high electrothermal performance and are expected to find different applications, e.g. various functional devices such as heating materials, heatable smart windows or dining tables.

In this paper, nanocomposite electrodes for rechargeable Lithium-ion battery composed of tin dioxide (SnO2) and multi-walled carbon nanotubes (MWCNTs) were prepared using the chemical deposition method with a subsequent sintering process. The as-prepared hybrids were characterized by thermal gravimetric analysis, Fourier transform infrared spectroscopy, X-ray diffraction and transmission electron microscopy. The results showed that the size of pure SnO2 particles was ∼5 nm and hybrids presented a uniform dispersion of SnO2 nanoparticles on the surfaces of the MWCNTs. The electrochemical properties of the composites were researched through a cyclic voltammetry and a galvanostatic charge–discharge test. It was found that the electrochemical performance of the composite was strongly dependent on the content of MWCNTs in the composites. The SnO2/MWCNT composite with 18.40 wt% MWCNTs gave the best performance, exhibiting a relatively higher reversible capacity of 475 mAh g−1 and an extended capacity retention of 65% even after 30 cycles at a current density of 78.2 mA g−1.

Single-walled carbon nanotubes (SWCNTs) were dispersed in water with the help of a combination of surfactants to achieve a high concentration SWCNT ink. Transparent conducting films (TCFs) were fabricated through a rod-coating method using the SWCNT ink. The addition of binders (polyacrylic acid or carboxymethyl cellulose) greatly enhanced the adhesion of SWCNT films to substrates and the cohesion between CNTs, which produced a uniform film of SWCNTs by preventing damage during the post-treatment process. The thickness of SWCNT films is controlled by the amount of SWCNTs in the solution and the diameter of the wire used. To test the film adhesion, Scotch™ tape was used to detach some loosely bound SWCNTs. Then the SWCNT films were further post-treated with nitric acid to improve the conductivity. The addition of polyacrylic acid to the SWCNT dispersion improved the film adhesion obviously without decreasing its electrical conductivity. This rod-coating method demonstrates great potential for the scalable fabrication of flexible SWCNT-TCFs.

Epoxy resin presents 3D cross-linking network structure characteristics after curing, resulting in a lower wear resistance of epoxy resin, which limits its extensive applications. In this paper, the effects of adding carboxyl functionalized carbon nanotubes on the tensile strength and wear resistance of carbon nanotube/epoxy composites were studied. The results showed that the tensile strength and wear resistance of the composites were effectively improved through carboxyl functionalization of carbon nanotubes.

This study introduced an innovative method to fabricate flexible transparent conducting films (TCFs) by spraying single-walled carbon nanotubes (SWCNTs) solution, dispersed by sodium dodecyl benzene sulfonate (SDBS), on polyethylene terephthalate (PET) substrate. The PET substrates were pretreated with nitric acid to improve the surface hydrophilicity. The films were spray deposited on the pretreated PET substrates in a two-step spray coating method. The film conductivity was further improved by nitric acid. As a convenient process, ultrasonication resonance method was applied to test the adhesion of TCFs. Comparing with the traditional preparation method, the adhesion of TCFs was enhanced and the mechanism was analyzed. The morphologies and thicknesses of TCFs were characterized by scanning electron microscopy and atomic force microscopy, while the Raman spectroscopy confirmed the structures of SWCNTs and the thickness changes of TCFs treated with different ultrasonication time.

Single-walled carbon nanotubes (SWCNTs) were dispersed in water with the help of surfactants to achieve high concentration SWCNT ink. SWCNT transparent conducting films (TCFs) were fabricated by rod coating using the SWCNT ink. A combination of two surfactants provided optimal rheological behaviour, which produced uniform films by preventing dewetting and rupture of SWCNTs during drying. The combination led to a dramatic increase of shear viscosities but no change of their wettability. The viscosity of SWCNT ink was controlled by the ratio of two surfactants. The thickness of SWCNT films could be easily varied by controlling both the concentration of SWCNT ink and the size of the wire-wound rod. The produced uniform SWCNT-TCFs treated by nitric acid have a relatively low sheet resistance of ∼80 Ω sq −1 at 80% transmittance. The performance has a wide range of applied interest for touch screen and flexible electronics.

In this work, multi-walled carbon nanotubes (MWCNTs) were functionalized to fabricate MWCNT/epoxy composites by incorporating MWCNTs into an epoxy. Cure behavior of composites was investigated by differential scanning calorimetry. Thermo-mechanical behavior of the composite was then evaluated by dynamic mechanical analysis. Tensile strength, elastic modulus and maximum elongation were obtained by tensile test using the CMT-4204 universal testing machine. A field-emission scanning electron microscope was also used to characterize the fracture mechanism of composites and the dispersion state of MWCNTs in the epoxy. The results showed that the introduction of MWCNTs decreased the activation energy of the reaction and promoted the cure reaction. The addition of MWCNTs, especially amino-functionalized MWCNTs, clearly improved the tensile strength. The functionalized MWCNTs improved the interfacial bonding and made the dispersion of MWCNTs homogeneous in the matrix, giving the composites present a better mechanical property.

a b s t r a c t This study evaluated the effect of sodium dodecyl benzene sulfonate (SDBS) as dispersant for the dispersion of purified single-walled carbon nanotubes (SWCNTs) in water in terms of dispersibility dependence on electrical conductivity of SWCNT transparent conducting film (TCF) performance. SWCNT TCFs were prepared by different proportions of CNTs/SDBS solution to find out the optimum SDBS concentration according to the film resistance of pristine and after post-treatment by nitric acid. TCFs fabricated with the aqueous solution by the ratio of CNTs/SDBS 1:5 gave the lowest sheet resistance and the highest transmittance. The TCFs were then further treated with thionyl chloride to improve their conductivity. Low sheet resistance (86 /, 80%T) was achieved. The dispersion condition of CNTs/SDBS aqueous solution was characterized by field-emission scanning electron microscopy, while the X-ray photoelectron spectroscopy and Raman spectroscopy confirmed the dispersion and doping mechanism treated with nitric acid and thionyl chloride.

Functionalization of multi-wall carbon nanotubes (MWCNTs) was achieved by grafting carboxyl groups and amino groups. Fourier transform infrared spectroscopy was used to detect the changes produced by functional groups on the surface of the MWCNTs. Three different MWCNTs were incorporated into epoxy resin and the friction and wear behavior of MWCNT/epoxy composites was investigated using a M-2000 wear testing machine at different sliding speeds under different applied loads. Scanning electron microscopy was used to observe the worn surfaces of the samples. The results indicated that the functional groups had been grafted on the surface of MWCNTs. Compared with neat epoxy, the composites with MWCNTs showed a lower friction coefficient and wear rate, and the wear rate decreased with the increase of MWCNT loading. Combining epoxy resin with MWCNTs is an efficient method to improve the wear resistance and decrease the coefficient of friction.

Single-walled carbon nanotubes were dispersed in deionized water with sodium dodecyl benzene sulfonate as surfactant. The solutions were sprayed on UV and plasma treated polyethylene terephthalate to achieve transparent conductive films with excellent adhesion. The carbon nanotube films were further treated with different concentrations of nitric acid to improve conductivity. SWCNTs and films were characterized by thermo gravimetric analysis, field-emitting scanning electron microscopy, UV-VIS spectrophotometer, four-point probe method, and Raman spectroscopy. The results demonstrated that the conductivity of carbon nanotube films with high transparency was improved to a greater degree with higher concentration of nitric acid due to effectively removing residual surfactants. The low sheet resistance films of ~100 Ω/sq @ 80T% have widely applications in touch screen, flat panel displays, organic light emitting diode, and etc.

In our study, air oxidation together with three different procedures for purifying single-walled carbon nanotubes (SWCNTs) was investigated. High purity SWCNTs were obtained. The purified SWCNTs were dispersed into four different types of dispersants and different ratio of SWCNTs to dispersant was evaluated in order to find the optimal condition. Transparent conducting films were fabricated by the purified and well dispersed SWCNT solution. Nitric acid concentration was optimized to enhance the film conductivity. SWCNT films with low sheet resistance and high transmittance were obtained by nitric acid treatment.

Interference fringes are obtained in a field-emission microscopy (FEM) study of a multi-walled carbon nanotube (MWCNT) with two open-ended branches. The FEM pattern, which is composed of three parallel streaks, can be interpreted by using classical Young's double-slit interference with the ends of the two MWCNT branches treated as two secondary sources of the electron wave. The origin of the coherency of the electron beams from the two branches is discussed on the basis of the quantitative analysis of the FEM pattern. The result suggests a new approach to obtaining a coherent electron source.

Nanodispersion of single-walled carbon nanotubes (SWCNTs) have been systematically investigated with the use of sodium dodecyl sulfate (SDS) and poly(vinylpyrrolidone) (PVP) surfactant in deionized water. A high concentration of nanodispersed SWCNTs up to 0.08 mg/mL was achieved with introduction of an additional dispersant of PVP by optimizing surfactant concentration, sonication time, and centrifugation speed, which was crucial to obtaining a high concentration of SWCNTs in the supernatant solution. We also demonstrate that diameters of the nanodispersed nanotubes can be sorted out by controlling the centrifugation speed, and furthermore, the saturated SWCNT concentration was nearly constant, independent of the initial concentration at high centrifugation speed. Two dispersion states were identified depending on the centrifugation speed: (I) an intermediate mixed state of nanodispersion and macrodispersion and (II) nanodispersion state. This was verified by Raman spectroscopy, scanning probe microscopy,...

We investigated the modulation of optical properties of single-walled carbon nanotubes (SWCNTs) by AuCl 3 doping. The van Hove singularity transitions (E 11 (S), E 22 (S), E 11 (M)) in absorption spectroscopy disappeared gradually with an increasing doping concentration and a new peak appeared at a high doping concentration. The work function was downshifted up to 0.42 eV by a strong charge transfer from the SWCNTs to AuCl 3 by a high level of p-doping. We propose that this large work function shift forces the Fermi level of the SWCNTs to be located deep in the valence band, i.e., highly degenerate, creating empty van Hove singularity states, and hence the work function shift invokes a new asymmetric transition in the absorption spectroscopy from a deeper level to newly generated empty states.

The effect of surfactant in dispersing single-walled carbon nanotubes (SWCNTs) to form conducting films were examined using UV–vis–NIR absorption spectroscopy. The distinctive sub-band transition peaks of sodium dodecyl sulfate (SDS)-dispersed SWCNTs in water were severely suppressed in the film due to the presence of residual SDS interacting strongly with SWCNTs. The recovery of electronic structures of SWCNTs could be monitored systematically using a simple acid treatment through the peak intensities and peak positions of the corresponding transition energies of absorption spectrum. The changes in electrical and optical conductivity of SWCNT film before and after acid treatment were discussed.

Several single-walled carbon nanotubes (SWCNTs) prepared by different methods have been used to investigate the material dependence on the optimal film performance of flexible transparent conducting films. The nanotubes were dispersed in water with sodium dodecyl sulfate by sonication. These SWCNT solutions were then sprayed onto the Poly(ethylene terephthalate) substrate by a spray coater to form the film. Several factors such as purity, diameter, defects, metallicity, and degree of dispersion were evaluated individually to examine how they affect the film performance. We found that the metallicity of SWCNTs and the degree of dispersion are the most crucial factors in determining the film performance. We also proposed a material quality factor to estimate the material quality of SWCNTs as a figure of merit for the film performance.

Field-ion microscopy (FIM), a tool for surface analysis with atomic resolution, has been employed to observe the end structure of single-walled carbon nanotubes (SWCNTs). FIM images revealed the existence of open SWCNT ends. Amorphous carbon atoms were also observed to occur around SWCNTs and traditional field evaporation failed to remove them. Heat treatment was found to be efficacious in altering the end structures of SWCNT bundles. Carbon and oxygen atoms released from heated tungsten filament are believed to be responsible for the decoration imposed on the SWCNT ends.

Single-walled carbon nanotube (SWCNT) transparent conducting films (TCFs) were fabricated for the electrodes of organic light-emitting diodes (OLEDs); three types of film were studied. The as-prepared SWCNT TCFs displayed a relatively low sheet resistance of 82.6 Ω/sq at 80.7 T% with a relatively large surface roughness of 30 nm. The TCFs were top-coated with poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) to obtain PEDOT:PSS-coated TCFs. The PEDOT:PSS cover improved the conductivity and decreased the surface roughness to 12 nm at the cost of film transmittance. The SWCNT TCFs mixed with PEDOT:PSS (PM-TCFs) exhibited a high conductivity (70.6 Ω/sq at 81 T%) and a low surface roughness (3 nm) and were thus selected as the best TCFs for OLEDs. Blue flexible OLEDs with 4,4'-bis(2,2'-diphenylvinyl)-1,1'-biphenyl (Dpvbi) as the emitting layer were fabricated on TCFs with the same structures to evaluate the performances of the different types of SWCNT films for use in OLEDs. Of these three types of OLEDs, the PM-TCF devices exhibited the optimal performance with a maximum luminance of 2587 cd m(-2) and a current efficiency of 5.44 cd A(-1). This result was explored using field-emission scanning electron microscopy and atomic force microscopy to further study the mechanisms that are involved in applying SWCNT TCFs to OLEDs.

Graphene oxide nanosheets (GONSs) with a lateral size less than 100 nm have attracted more and more attention for their wide range of potential applications, from bionanotechnology and nanobiomedicine to surfactants. However, at present GONSs are commonly prepared from graphite nanofibers or graphite nanopowders which are both expensive. Here, a timesaving, low-cost, high-yield method is proposed for preparing ultrasmall uniform GONSs with an average lateral size of ∼30 nm, utilizing common graphite powder as the raw material in the absence of a strong acid. The obtained GONSs are able to disperse single-walled carbon nanotubes (SWCNTs) effectively, and the dispersion could withstand high-speed centrifugation. Consequently, GONSs could indeed serve as a superior surfactant for the dispersion of SWCNTs, and the dispersion could be further applied in electronics, as the GONSs may be further reduced to reduced GONSs or graphene nanosheets.

Nanodispersion of single-walled carbon nanotubes (SWCNTs) has been systematically investigated with the use of sodium dodecyl sulfate (SDS) and poly(vinylpyrrolidone) (PVP) surfactant in de-ionized water. A high concentration of nanodispersed SWCNTs up to 0.08 mg/mL was achieved with introduction of an additional dispersant of PVP by optimizing surfactant concentration, sonication time, and centrifugation speed, which was crucial to obtaining a high concentration of SWCNTs in the supernatant solution. We also demonstrate that diameters of the nanodispersed nanotubes can be sorted out by controlling the centrifugation speed and furthermore the saturated SWCNT concentration was nearly constant, independent of the initial concentration at high centrifugation speed. Two dispersion states were identified depending on the centrifugation speed: an intermediate dispersion of nanodispersion mixed with macrodispersion (I) and nanodispersion (II). This was verified by Raman spectroscopy, scanning probe microscopy, optical absorption spectroscopy, and photoluminescence measurements. The obtained SWCNT solution was stable up to about ten days. Some aggregated SWCNT solution after a long period of time was fully recovered to initial state of dispersion after re-sonication for a few minutes. Our systematic study on high concentration nanodispersion of SWCNTs with selective diameters provides an opportunity to extend the application areas of high quality SWCNTs in large quantity.

Flexible transparent conducting films (TCFs) were fabricated on a PET substrate by various methods using carbon nanotubes dispersed in organic or water-based solution. Thin multi-walled carbon nanotubes, double-walled carbon nanotubes, and single-walled carbon nanotubes were used to compare the performance for TCFs. Optimal design rules for types of nanotubes, surfactants, the degree of dispersion, and film preparation methods were discussed. The TCFs were characterized by scanning electron microscopy, TGA, Raman, optical absorption spectra, and sheet resistance. The dispersion of CNTs in water and in bisolvent has been tried. A simple acid treatment on the TCF film increased the conductivity by about four times. Doping and functionalization techniques will be further introduced to improve the conductivity of the film.

Flexible transparent conducting films with sodium dodecyl sulfate-dispersed singlewalled carbon nanotubes (SWCNTs) were prepared by a spray method and were further immersed in various acids. The film conductivity was enhanced by a factor of ∼4 with a negligible change in the transmittance in the visible range. This enhancement was attributed to the removal of remaining SDS and the subsequent densified film formation to improve the cross-junction resistance between SWCNT networks and enhanced metallicity of SWCNTs.

Carbon nanotube (CNT)-anchored polymer nanofiber mats were designed by in situ spraying of carbon nanotubes while simultaneously electrospinning polymer nanofibers. The improved conductivity of the composite mat, high catalytic current (3400 mA/cm2/mg Pt) and long term stability of the composite mat was attributed to the efficient formation of CNT bridges between nanofibers.

Single-walled carbon nanotubes (SWCNTs) dispersed with Nafion in a solvent mixture containing de-ionized water and 1-propanol (bisolvent) were sprayed on a poly(ethylene terephthalate) substrate to fabricate flexible transparent conducting films (TCFs). Different SWCNT-to-Nafion ratios were used to optimize the film performance of transparence and sheet resistance. The TCFs were then immersed in nitric acid. These steps resulted in p-type doping due to the presence of Nafion in the SWCNT network and de-doping (removal of doping effect) by the acid treatment. X-Ray photoelectron and Raman spectroscopy confirmed that the de-doping effect occurred with the partial removal of Nafion from the nanotube surface by the nitric acid treatment, which improved the film conductivity by a factor of ∼4 with negligible change in transmittance.

Arrays of multi-walled carbon nanotube (MWCNT) were bombarded with argon ions a nd studied with transmission electron microscopy and x-ray photoelectron spectr oscopy. Our preliminary results show that after 35min ion bombardment, most of the MWCNT curls and the iron catalyst particles residing at the top end of the tube were knocked out. Although no obvious change in its emission images is obse rved, its field emission current considerably decreases. During spontaneous cool ing down from an elevated temperature (480℃), its emission current decreases sh arply. Interesting finding is that the coating of phosphor powder on the tin-oxide-coated glass anode significantly affects the emission current measurement . For example, the phosphor coating reduces the measured current by over 30?tim es and increases the turnon field from 1.0 to 2.0V/μm.

Influence of oxygen on the field emission of singlewalled carbon nanotubes (SWCNTs) was studied using a fieldemission microscope (FEM) and a quadrupole mass spectrometer. After heat treatment at 1000℃, the field emission of clean SWCNTs occurred. Then oxygen was introduced into the vacuum system and the curves of field emission current versus anodecathode voltage (IV curves) were acquired after oxygen adsorption and desorption, respectively. We have observed that oxygen adsorption on SWCNTs leads to a decrease in field emission current, indicating an increase in the work function. Oxidation etching occurred when the SWCNTs were annealed at about 1000℃ under a pressure of 10-4Pa, and the corresponding changes were observed in both field emission images and IV curves.