Aligned Nanotubes Research Articles

Tuning electric field aligned CNT architectures via chemistry, morphology, and sonication from micro to macroscopic scale.

Electric-field alignment of carbon nanotubes (CNT) is widely used to produce composite materials with anisotropic mechanical, electrical, and optical properties. Nevertheless, consistent results are difficult to achieve, and even under identical electric field conditions the resulting aligned morphologies can vary over μm to cm length scales. In order to improve reproducibility, this study addresses (1) how solution processing steps (oxidation, sonication) affect CNT properties, and (2) how CNT chemistry, morphology, and dispersion influence alignment. Aligned CNT were deposited onto PVDF membranes using a combination of electric-field alignment and vacuum-filtration. At each step in solution processing, the CNT chemistry (oxygen content) and morphology (length/diameter) were characterized and compared to the final aligned morphology. Well-dispersed CNT with high oxygen content (>8.5%O) yielded uniform membrane coatings and microscopically aligned CNT, whereas CNT with low oxygen CNT (<2.2%O) produced aligned bundles visible at a macroscopic level, but microscopically the individual CNT remained disordered. Based on regression analysis, CNT with larger mean length and diameter, smaller length and diameter variation, and higher oxygen content yielded increased electrical anisotropy, and bath sonication was slightly preferable to probe sonication for initial dispersion.

Fabrication and Characterization of Aligned Carbon Nanotubes Cluster Reinforced Magnesium Composite Based On Ultrasound/Magnetic Compound Field

Abstract Carbon nanotubes (CNTs)-based materials have been the focus of intense research since their discovery because of their superior mechanical properties, good electrical conductivity and unique nano-effect of unique one dimensional nanostructures. Control and manipulation of the alignment of CNTs in the matrix can effectively affect the electrical, optical and mechanical properties of the composites. At present, there are many researches on the magnetic-field induced the alignment of CNTs in the polymer matrix, but less research on magnetic- field induced the alignment of CNTs in the metal matrix. In order to realize the alignment of CNTs in metal matrix, CNTs were firstly magnetically modified by electroless plating, and a uniform layer of cobalt nanoparticles was successfully plated on the surface of carbon nanotubes. For facilitating the macro-analysis of the different factors on the cobalt-carbon nanotubes directional effect, three kinds of matrixes (distilled water, vegetable oil and high viscosity glue) were used to simulate the magnesium alloy melt. The effects of ultrasonic, magnetic field and temperature on the Co coated CNTs dispersion and alignment in three kinds of matrix were studied by orthogonal test. It was found that the dispersion of CNTs was significantly affected by ultrasound and the alignment of CNTs affected by the magnetic field intensity. In this paper, the CNTs / Mg composites were prepared by liquid-state method and the wettability between CNTs and Mg alloy was improved by the modification of carbon nanotubes. Under the compound effect of ultrasonic and magnetic field, the alignment of the carbon nanotubes cluster in magnesium matrix composites was quantitatively characterized by Image J software. It is found that the Cobalt particles coated CNTs can respond well to magnetic field (typically 0.3–0.8T). With the increase of magnetic field strength, CNTs show higher relative frequencies along the magnetic field direction. When the magnetic field strength was 0.8T, the relative frequencies within 20-50° was 0.7. This indicated that Co-CNTs can achieve obviously alignment in AZ91D alloy under a low magnetic field. In addition, the compressive specimens were prepared according to the optimum process parameters determined by the orthogonal test. The compressive properties of the composites parallel to and perpendicular to the direction of the magnetic field were studied. The results shown that the compressive strength of the Co-CNTs/Mg composites was obviously higher than that of the magnesium matrix and exhibited anisotropy due to directional aligned carbon nanotube.

移動電界を印加したカーボンナノチューブ/紫外線硬化性樹脂複合材の電気的特性とカーボンナノチューブの配列シミュレーション

This study sought to align multiwalled carbon nanotubes in uncured ultraviolet ray curing resin suspension by applying traveling electric field in the whole area. The suspension coated on a 18mm × 18mm size cover glass and the coated cover glass were put on the multiple-electrode which was constructed with 24 long and slender electrodes. Rectangular and six-phase voltages were applied to the multiple-electrode. The applied voltage in one electrode had the phase differences of ±60 degrees among the voltages applied to the both side electrodes. The multiwalled carbon nanotubes in the suspension were rotated to the direction perpendicular to the electrodes. After the rotation ceased, UV rays were irradiated to the suspension for resin curing. In this way, aligned carbon nanotubes/ ultraviolet curing resin composites were produced. The electrical resistivities of the composites were measured in parallel and vertical directions to the aligned carbon nanotubes. In the latter half of this paper, the carbon nanotubes alignment was simulated under the experimental condition based on the method proposed by the author. Furthermore, the influence of the relative permittivity of the suspension on the fluctuation of the carbon nanotube orientation was theoretically clarified.

Large-area assembly of halloysite nanotubes for enhancing the capture of tumor cells.

Here, polystyrene sulfonate sodium (PSS) modified Halloysite nanotubes (HNTs) were self-assembled into a patterned coating on a glass substrate with ordered nanotube arrays in a slit-like confined space. The microstructure of the formed patterned HNTs coating was investigated. The formed strips are more regular and almost parallel to each other with an increase in HNTs concentration. The HNTs coating formed from the 2% PSS-HNTs dispersion has the maximum nanotube alignment degree. The patterned HNTs coating was employed to capture tumor cells. The tumor cells can be captured by the HNTs coating effectively compared with a smooth glass surface due to the enhanced topographic interactions between the HNTs coating and cancer cells. The HNTs coating prepared from the 2% PSS-HNTs dispersion has the highest capture yield which is due to the ordered nanotube arrangement and the appropriate surface roughness. The HNTs coating was further conjugated with anti-EpCAM, which leads to the capture yield of MCF-7 cells reaching 92% within 3 h. The HNTs coating can capture 8 MCF-7 cells from 1 mL artificial blood samples spiked with 10 MCF-7 cells, showing the promising applications of HNTs in clinical circulating tumor cell capture for early diagnosis and monitoring of cancer patients.

Surface modification of TiO2 nanotubes with osteogenic growth peptide to enhance osteoblast differentiation

To investigate the influence of surface-biofunctionalized substrates on osteoblast behavior, a layer of aligned TiO2 nanotubes with a diameter of around 70nm was fabricated on titanium surface by anodization, and then osteogenic growth peptide (OGP) was conjugated onto TiO2 nanotubes through the intermediate layer of polydopamine. The morphology, composition and wettability of different surfaces were characterized by field-emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and contact angle measurements, respectively. The effects of OGP-modified TiO2 nanotube substrates on the morphology, proliferation and differentiation of osteoblasts were examined in vitro. Immunofluorescence staining revealed that the OGP-functionalized TiO2 nanotubes were favorable for cell spreading. However, there was no significant difference in cell proliferation observed among the different groups. Cells grown onto OGP-functionalized TiO2 nanotubes showed significantly higher (p<0.05 or p<0.01) levels of alkaline phosphatase (ALP) and mineralization after 4, 7 and 14days of culture, respectively. Cells grown on OGP-functionalized TiO2 nanotubes had significantly higher (p<0.05 or p<0.01) expression of osteogenic-related genes including runt related transcription factor 2 (Runx2), ALP, collagen type I (Col I), osteopontin (OPN) and osteocalcin (OC) after 14days of culture. These data suggest that surface functionalization of TiO2 nanotubes with OGP was beneficial for cell spreading and differentiation. This study provides a novel platform for the development and fabrication of titanium-based implants that enhance the propensity for osseointegration between the native tissue and implant interface.

Shear Alignment of Bola-Amphiphilic Arginine-Coated Peptide Nanotubes.

The bola-amphiphilic arginine-capped peptide RFL4RF self-assembles into nanotubes in aqueous solution. The nanostructure and rheology are probed by in situ simultaneous rheology/small-angle scattering experiments including rheo-SAXS, rheo-SANS, and rheo-GISANS (SAXS: small-angle X-ray scattering, SANS: small-angle neutron scattering, GISANS: grazing incidence small-angle neutron scattering). Nematic alignment of peptide nanotubes under shear is observed at sufficiently high shear rates under steady shear in either Couette or cone-and-plate geometry. The extent of alignment increases with shear rate. A shear plateau is observed in a flow curve measured in the Couette geometry, indicating the presence of shear banding above the shear rate at which significant orientation is observed (0.1-1 s-1). The orientation under shear is transient and is lost as soon as shear is stopped. GISANS shows that alignment at the surface of a cone-and-plate cell develops at sufficiently high shear rates, very similar to that observed in the bulk using the Couette geometry. A small isotope effect (comparing H2O/D2O solvents) is noted in the CD spectra indicating increased interpeptide hydrogen bonding in D2O, although this does not influence nanotube self-assembly. These results provide new insights into the controlled alignment of peptide nanotubes for future applications.

Two-Dimensional Alignment of Self-Assembled Organic Nanotubes through Langmuir-Blodgett Technique.

A C3-symmetric molecule was found to form organic nanotubes through supramolecular gel formation in organic solvents. These nanotubes can be dispersed in toluene without destroying the tubular nanostructures. Using the dispersions of these organic nanotubes as "spreading solutions", Langmuir-spreading films of these nanotubes were formed. Through repeated compression and expansion cycles, the nanotubes can be aligned to a certain extent. The formed Langmuir films could be subsequently transferred to a solid substrate, and the well-aligned nanotube films were constructed by Langmuir-Blodgett film deposition technique. Interestingly, many guests including polymers, water-soluble or oil-soluble organic molecules can be encapsulated into the nanotubes and further spread on a water subphase. Through elaborate control, large-scale parallel alignment of self-assembled organic nanotubes encapsulated by guests was also realized. This study implies that 2D hierarchical alignment of one-dimensional organic nanostructures can be realized using a simple method.

Nano-structural variation of highly aligned anodic Titania nanotube arrays for gas phase photocatalytic application

Abstract Highly aligned titania (TiO 2 ) nanotube (NT) arrays have been grown on titanium sheet by using a self organized anodic oxidation method at different potentials (34–74 V) in a NH 4 F and ethylene glycol based electrolyte. Two sets of TiO 2 NT arrays have been fabricated with and without using cooling systems. Without cooling system, the solution temperature is increased from 25 °C (room temperature) to 63 °C with increase of anodization potential from 34 to 74 V. The temperature has been maintained to 25 °C by using water based cooling system. In both sets of samples, the pore diameter of TiO 2 NT arrays increases with increase of anodization potential. The maximum pore diameter has been (outer: 224 nm, inner: 172 nm) achieved with TiO 2 NT arrays (at 74 V) without using cooling system. The photocatalytic activity of the TiO 2 NT arrays is evaluated by the decomposition of methanol by the use of Fourier transform infrared spectrophotometer. The TiO 2 NT (at 44 V) sample has been fabricated without using cooling system, which shows the higher photocatalytic activity than the sample at other potentials. Using cooling system, the TiO 2 NT (at 54 V) sample shows the higher photo-decomposing property than the sample at other potentials. The TiO 2 NT (at 54 V) sample with cooling system shows the higher rate (photocatalytic activity) constant ( k = 0.0216) than the TiO 2 NT (at 44 V) sample without using cooling system ( k = 0.0186). The photocatalytic activity has been correlated with the nanostructural variation of TiO 2 NT arrays at different potentials without (self-grown solution temperature) and with water based cooling systems.

Modeling of dynamic mechanical properties of polymer composites reinforced by one dimensional nanofillers

Owing to their high aspect ratio, large specific surface area, high axial Young's modulus/strength, and low density, one dimensional carbon nanomaterials can introduce significant change to the mechanical properties of polymer matrices, both static and dynamic. Thus, one of the most important potential applications of carbon nanotubes or nanofibers is to utilize the enhanced dynamic damping properties of polymer nanocomposites for improved vibration, acoustic, and fatigue performances. This study focuses on calculating the nanocomposite energy dissipation under dynamic mechanical loading. A micromechanical model based on quasi-static stick-slip analysis has been developed to quantify the dynamic mechanical properties of the nanocomposites as a function of external strain in the elastic region. Storage and loss moduli are used to characterize such dynamic mechanical behaviors. Influences of nanotube bundling and nanotube alignment on the damping property of composites have been quantified. Simulation results are in good agreement with the reported experimental measurements.

New processing method to fabricate high-performance carbon-nanotube/polyvinyl alcohol composite films

Bad dispersion, low volume fraction, and poor alignment of long carbon nanotubes (CNTs) in a polymer matrix are the main reasons for the disappointing performance of CNT reinforced polymer composites. Here, we report a novel technique for the preparation of high performance CNT/Polyvinyl alcohol (PVA) composite films, involving continuous production of a hollow cylindrical CNT assembly from a tubular reactor and its in-situ deposition on a paper substrate wrapped on a winding drum under the spray of a PVA solution. The distribution, alignment and loading of CNTs in the composite film are easily tailored by changing the winding rate and the PVA concentration in the spray solution. It is found that the properties of the prepared film are strongly dependent upon the CNT loading in the film. At the optimal high CNT loading of 56.8 wt%, the tensile strength has reached 3.16 GPa, and electrical conductivity 1322 S cm−1. This combination of mechanical and electrical properties is superior to any other CNT/polymer composites developed to date. In terms of its versatility and simplicity, the reported process paves a new way for continuous production of high-performance CNT reinforced composites.

Real-time assessment of carbon nanotube alignment in a polymer matrix under an applied electric field via polarized Raman spectroscopy

A technique has been developed utilizing polarized Raman spectroscopy to measure alignment of carbon nanotubes in situ in a polymer matrix under an applied electric field. Previous studies of alignment have been restricted to optically transparent solvents or polymerized specimens that prevent accurate analyses of alignment dynamics in polymers. The effects of electric field strength on the degree of alignment and the time to achieve an aligned state are discussed. The use of in situ, real-time polarized Raman spectroscopy provides a non-invasive technique for assessing carbon nanotube alignment, which can assist in determining processing conditions to improve the mechanical and electrical properties of aligned nanocomposites.

Nitrogen and Transition-Metal Codoped Titania Nanotube Arrays for Visible-Light-Sensitive Photoelectrochemical Water Oxidation

The anodization of a titanium metal sheet to form aligned titanium dioxide nanotubes (TNTs) is of considerable research interest in fields such as photocatalysts, solar cells, and sensors due to their aligned nanostructure and high surface area [1]. Owing to wide band gap (3.2 eV) of TiO2, TNTs can utilize only UV, which is 3-4 % of solar light energy. It is an important issue to develop new TNTs with enhanced photocatalytic activities under visible-light irradiation. In the research field of TiO2 particles, impurity doping such as nitrogen is one of typical approaches to extend spectral response of TiO2 to visible light region [2]. Moreover, codoping of nitrogen and metal ion possesses potential to induce formation of new states which are close to the valence band and conduction band edges, respectively [3, 4]. The codoping approach is an efficient way to absorb wider spectrum of solar irradiation by TiO2 for photoelectrochemical water splitting for solar hydrogen generation and CO2 reduction reaction [5, 6]. In this work, we report on fabrication of novel TNT arrays codoped with nitrogen (N) and earth-abundant 3d-transition metals (TM) for visible-light-driven photoelectrochemical water oxidation. The fabrication method for N and TM (TM: Fe, V, Cr, or Co) codoped TNT [(N, TM)-TNT] arrays were via an anodization process using low concentration transition metal (0.05-0.13 at%)-Ti alloys and a subsequent nitridation process. Vertically aligned N and TM (TM: Fe, V, Cr, or Co) codoped TMT (N, M-TNT) with external diameter of ca. 100 nm and length of ca.3000 nm were successfully fabricated. XRD patterns of all (N, TM)-TNT samples have broad peaks assignable to the typical anatase phase. Photoelectrochemical measurements were performed in a 3-electrode cell containing 0.1 M KOH with a (N, TM)-TNT photoanode, a platinum cathode, and a Ag/AgCl reference electrode. The codoping of N and TM substantially improved the photocurrent of the TNT photoanode under visible light irradiation due to the formation of impurity levels by N and TM. The rate of increase in the photocurrent was dependent on transition metal species and it was found that codoping of iron showed the greatestest enhancement. N, Fe(0.13at%) codoped TNT [(N, Fe0.13)-TNT] photoanode modified with cobalt borate (Co-Bi) co-catalyst yielded a visible-light-induced water oxidation with a photocurrent density of 0.76 mA/cm2 at +0.6 V (vs. Ag/AgCl) under visible light irradiation, which was 13 times and 5 times higher than that of Fe0.13-TNT and N-TNT, respectively. In addition, O2 generation and the photocurrent were confirmed repeatedly during visible-light irradiation with high current efficiency (≥95%) and these results indicate that the observed photocurrent originated from water-splitting reaction [7]. The photoelectrochemical water oxidation activity of codoped TNT could be further improved by optimizing the amount of doping, kind of dopant, and nanotube structure. This scalable method for codoping to TNT can also be extended to other metal oxide nanotubes. [References] [1] P. Roy, et. al., Angew. Chem. Int. Ed., 50(2011) 2904. [2] R. Asahi, T. Morikawa, et al., Science, 293(2001) 269. [3] Y. Gai, J. Li, et al., Phys. Rev. Lett., 102(2009) 036402. [4] W. Zhu, et al., Phys. Rev. Lett., 103(2009) 226401. [5] S. Sato, T. Arai, et al., J. Am. Chem. Soc., 133(2011) 15240. [6] T. Arai, et al., Energy Environ. Sci., 6(2013) 1274. [7] T. M. Suzuki, et al., Chem. Commun., 50 (2014) 7614.

Spray-Coated Halloysite–Epoxy Composites: A Means To Create Mechanically Robust, Vertically Aligned Nanotube Composites

Halloysite nanotube-filled epoxy composites were fabricated using spray-coating methods. The halloysite nanotubes (HNTs) were aligned by the hydrodynamic flow conditions at the spray nozzle, and the polymer viscosity helped to preserve this preferential orientation in the final coatings on the target substrates. Electron microscopy demonstrated a consistent trend of higher orientation degree in the nanocomposite coatings as viscosity increased. The nanoindentation mechanical performances of these coatings were studied using a Hysitron TriboIndenter device. Composites showed improvements up to ∼50% in modulus and ∼100% in hardness as compared to pure epoxy, and the largest improvements in mechanical performance correlated with higher alignment of HNTs along the plane-normal direction. Achieving this nanotube alignment using a simple spray-coating method suggests potential for large-scale production of multifunctional anisotropic nanocomposite coatings on a variety of rigid and deformable substrates.

Effect of Ferrocene Catalyst and Hydrogen Feed on Microstructures of Vertically Aligned MWCNTs

This study investigated the effect of catalyst amount on chemical vapour deposition (CVD) growth of multi-walled carbon nanotubes (MWCNTs) with and without hydrogen feed. The ferrocene weight was varied from 100 mg to 200 mg for CNTs growth over Si/SiO2/Al2O3 substrate. Very few CNTs were seen in micrographs of the samples produced in the absence of the hydrogen feed. Most of the carbon atoms precipitated into amorphous carbon due to existence of inactive catalyst particles. However, CNT structures grown with hydrogen feed were more distinct; the nanotubes were thinner, straight and highly crystalline. MWCNTs arrays/forest length was also increased from 120 µm to 850 µm with hydrogen feed. An increase in catalyst weight significantly affected the diameter, crystallinity, alignment and growth of nanotubes. The lowest inner-shell spacing of 0.348 nm was obtained with 150 mg of ferrocene, which is an indication of growth of relatively pure CNTs. Under the optimum conditions, the areal density of the ferrocene particles was sufficiently increased to get required alignment and crystallinity of MWCNTs.

Influence of Alignment and Dispersion Pattern of Carbon Nanotubes in the Polycarbonate and Polystyrene Matrixes on Laser Cutting Worka-bility

Influence of Alignment and Dispersion Pattern of Carbon Nanotubes in the Polycarbonate and Polystyrene Matrixes on Laser Cutting Worka-bility

Silencing tumor necrosis factor-alpha in vitro from small interfering RNA-decorated titanium nanotube array can facilitate osteogenic differentiation of mesenchymal stem cells.

Titanium implants are known for their bone bonding ability. However, the osseointegration may be severely disturbed in the inflammation environment. In order to enhance osseointegration of the implant in an inflamed environment, the small interfering RNA (siRNA) targeting tumor necrosis factor alpha (TNF-α) was used to functionalize titanium surface for gene silencing. The chitosan–tripolyphosphate–hyaluronate complexes were used to formulate nanoparticles (NPs) with siRNA, which were adsorbed directly by the anodized titanium surface. The surface characterization was analyzed by scanning electron microscope, atomic force microscopy, as well as contact angle measurement. The fluorescence microscope was used to monitor the degradation of the layer. The coculture system was established with mesenchymal stem cells (MSCs) grown directly on functionalized titanium surface and RAW264.7 cells (preactivated by lipopolysaccharide) grown upside in a transwell chamber. The transfection and knockdown efficiency of TNF-α in RAW264.7 cells were determined by fluorescence microscope, quantitative polymerase chain reaction, and enzyme-linked immunosorbent assay. The cytoskeleton and osteogenic differentiation of MSCs were also analyzed. Regular vertical aligned nanotubes (~100 nm diameter and ~300 nm length) were generated after anodization of polished titanium. After loading with NPs, the nanotubes were filled and covered by a layer of amorphous particles. The surface topography changed and wettability decreased after covering with NPs. As expected, a burst degradation of the film was observed, which could provide sufficient NPs in the released supernatant and result in transfection and knockdown effects in RAW264.7 cells. The cytoskeleton arrangement of MSCs was elongated and the osteogenic differentiation was also significantly improved on NPs loading surface. In conclusion, the siRNA decorated titanium implant could simultaneously suppress inflammation and improve osteogenesis, which may be suitable for peri-implant bone formation under inflammatory conditions.

Processing and property investigation of high-density carbon nanostructured papers with superior conductive and mechanical properties

Recently, Lockheed Martin Corporation has synthesized special types of carbon nanostructures (CNSs) that are made of highly aligned, but highly cross-linked, and relatively long carbon nanotubes that are bundled in flack-shaped architectures. In this paper, a simple and scalable method is developed for making very electrically conductive and mechanically strong paper sheets using these novel pre-aligned CNS materials to be used in various engineering applications. The electrical conductivity and mechanical properties of the as fabricated paper sheets have been improved significantly by increasing their density from 0.6 to 1.6g/cm3 through pressing. The scanning electron microscope images of the surface and cross-section of the as fabricated and pressed papers show a very high degree of carbon nanotubes alignment, which indicated that the pre-alignment of CNSs remained unaltered even after the sonication and the pressing process. The electrical conductivity of the papers has been improved by 113% with increasing the density of the CNS papers. In addition, the mechanical properties improved with increasing the density. The tensile strength and the Young's modulus improved by 67% and 86% respectively as the density increases.

High‐Performance Multifunctional Thermoplastic Composites Enhanced by Aligned Buckypaper

High‐performance lightweight composites are sizably manufactured by impregnating continuous aligned carbon nanotube sheet (buckypapers) with self‐reinforcing polyphenylene (Parmax) solution and followed by hot‐press. The high processing pressure flattens nanotubes, which preferably π‐stack with the aromatic rings of Parmax chain, and accordingly improve the load transfer. Both tensile strength and Young's modulus of the thermoplastic composites increase with the alignment degree of nanotubes, and can reach 950 MPa and 94 GPa, respectively, for the composite containing 50%‐stretched buckypaper. The highly aligned nanotubes also boost phonon transfer (70 W mK−1) and the electric conductivity (425 S cm–1) of the composite along the alignment direction. These combined outstanding properties would enable the thermoplastic composites in wide applications as multifunctional material.

Magnetocaloric effect at cryogenic temperature in gadolinium oxide nanotubes

We have synthesized fascinating nano-structure of Gadolinium oxide (Gd2O3) using controlled template-assisted electrochemical deposition technique which showed interesting anisotropic magnetic behavior. The nanotubes of Gd2O3 with average diameter 200nm, length 10µm and wall thickness 20nm are constituted of nanoclusters with average diameter 7.5nm. The tubes are aligned and are almost uniform throughout their length. Detailed magnetic measurements of aligned Gd2O3 nanotubes have been performed for both parallel and perpendicular magnetic field orientations with respect to the axis of the Gd2O3 nanotube array. Significant differences in magnetization values have been observed between the parallel and perpendicular orientations. Experimental results indicate the superparamagnetic nature of the nanomaterial. Large magnetocaloric effect, associated with the sharp change in magnetization of the Gd2O3 nanotubes, has been observed in the cryogenic temperature regime that shows anisotropic behavior.

Observation of enhanced field emission properties of Au/TiO2 nanocomposite

Simple and low-cost method of thermal annealing was used to decorate Gold (Au) nanoparticles on aligned TiO2 nanotubes. The aligned TiO2 nanotubes were decorated by Au nanoparticles with an average diameter of 9, 18 and 28 nm (aligned TiO2 nanotubes referred as specimen A and TiO2 nanotubes decorated by Au nanoparticles with average diameter of 9, 18 and 28 nm are referred as specimen B, C and D, respectively). The detailed characterization such as structural, morphological and elemental analysis of TiO2 and Au/TiO2 nanocomposite have been carried out using X-ray diffraction, field emission scanning electron microscope, transmission electron microscope, X-ray photoelectron spectroscopy and Raman spectroscopy. Furthermore, the meticulous comparative field emission characteristics of the aligned TiO2 nanotubes and Au/TiO2 nanocomposite have been performed. The turn-on field defined for the current density of 10 μA/cm2 has been found to be 3.9, 2.8, 3.2 and 3.7 V/μm for specimen A, B, C and D, respectively. The observed low turn-on field of specimen B has been found to be superior than the other semiconducting nanocomposites reported in the literature. The emission current stability over a period of 3 h is found to be better for all the specimens. To the best of our knowledge, a systematic field emission study of Au/TiO2 nanocomposite has not been explored. The observed superior field emission study of Au/TiO2 nanocomposite indicates their possible use in micro/nanoelectronic devices.