Nanotube Composite Films Research Articles

Ultra-low power resistive random-access memory based on VO2/TiO2 nanotubes composite film

In this study, a resistive random access memory (RRAM) based on VO2/TiO2 nanotubes was prepared. Compared with single VO2-based RRAM or TiO2 nanotube-based RRAM, the Ag/VO2/TiO2 nanotube/FTO RRAM device has advantages such as low power consumption (∼0.154 pJ), excellent stability (3000 DC cycles), and high switching rate (300 times). It still shows certain advantages compared with TiO2-based low-power RRAM (0.5 pJ). The device can also exhibit 20 consecutive long-term enhancement/suppression behaviors, which can be used to simulate brain-like activity and achieve recognition accuracy of 95% (8 × 8 pixels) and 88% (28 × 28 pixels) in artificial neural network identification field.

Rational design of MXene/Boron Carbon Nitride nanotube composite electrode for supercapacitors with improved electrochemical properties

3D structures obtained using 1D and 2D materials are promising materials in energy storage. Optimizing the interlayer spacing of 2D MXene through flexible conductive materials is an important step in synthesizing 3D composite electrodes. In this study, flexible and conductive MXene/BCN nanotube composite film electrodes were prepared by vacuum filtration using BCN nanotubes in different weight ratios (10 %, 20 %, and 30 %) in mixed and sandwiched structures. The mixed MXene/BCN10 (m-MX/BCN10) composite film electrode structure attained a specific capacitance of 678 F g−1, the highest of all tested electrodes, and exhibited remarkable cycle stability by retaining 95 % of its capacitance even after 10,000 charge/discharge cycles. In the symmetric supercapacitor (SSC), the cell exhibited a specific capacitance of 97 % after 10,000 charge/discharge cycles. Moreover, SSC showed an energy density of 32 Wh kg−1 and a power density of 11.5 kW kg−1. The composite electrodes made of 2D Ti3C2Tx MXene and 1D BCN nanotube materials open up a new avenue for synthesizing promising materials for energy storage in transition metal carbides and 1D nanotubes or nanowires.

Binder-Free CoMn2O4 Nanoflower Particles/Graphene/Carbon Nanotube Composite Film for a High-Performance Lithium-Ion Battery

Manganese-based bimetallic oxides show a high theoretical specific capacity, making them a potential next-generation lithium-ion battery anode material. However, as with metal oxide anode materials, aggregation, volume expansion, and poor conductivity are the main obstacles. In this manuscript, flexible CoMn2O4/graphene/carbon nanotube films were successfully prepared through a facile filtration strategy and a subsequent thermal treatment process. When used as anodes for lithium batteries, these films can be pressed onto nickel foam without other conductive additives and binders, which simplifies the manufacturing process. When used as an anode in the lithium-ion battery, CoMn2O4/GR/CNT film exhibits a high discharge capacity of 881 mAh g−1 after 55 cycles. This value is ~2 times higher than the discharge capacity of CoMn2O4. The three-dimensional GR/CNT carrier effectively dispersed CoMn2O4, preventing its aggregation and alleviating the problem of volume expansion.

Flexible, Wearable, and Ultralow-Power-Consumption Electronic Skins Based on a Thermally Reduced Graphene Oxide/Carbon Nanotube Composite Film

Flexible, Wearable, and Ultralow-Power-Consumption Electronic Skins Based on a Thermally Reduced Graphene Oxide/Carbon Nanotube Composite Film

High-performance g-C3N4 coated single-walled carbon nanotube composite films for flexible thermoelectric generators

Thermoelectric (TE) devices consisting of p-type and n-type single-walled carbon nanotubes (SWCNTs) based films, which can gather waste heat and turn it into electrical power, show potential application in supplying power for wearable electronic devices. In this study, graphitic carbon nitride (g-C3N4) has been prepared by high temperature pyrolysis of melamine and confirmed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction pattern (XRD), respectively. Then the prepared g-C3N4 is composited with SWCNTs via mechanical mixing and vacuum-filtering method to obtain free-standing flexible g-C3N4/SWCNT thermoelectric composite films. The results demonstrate that g-C3N4 is efficiently covered on the surface of SWCNTs via interfacial π-π interaction, and g-C3N4 layer with several nanometers coated on SWCNTs simultaneously improves the electrical conductivity (σ) and the Seebeck coefficient (S) of g-C3N4/SWCNT. At a mass ratio of 2.5 % for g-C3N4/SWCNT, an optimal power factor value of 163.0 ± 1.0 μW m−1 K−2 is obtained for g-C3N4/SWCNT with the σ of 702.6 ± 1.6 S cm−1 and the S of 48.2 ± 0.2 μV K−1 at room temperature. Finally, a self-powering TE device composed of three pairs of p-n junctions is manufactured, and the actual output power is about 1.13 μW at the temperature difference of 50 K. As a result, this study offers a straightforward way to enhance the thermoelectric performance of single-walled carbon nanotubes, which can be utilized in flexible power generators.

Correction: Facile preparation of OHB-T–carbon nanotube composite films for modification of the electrical and optical properties

Correction: Facile preparation of OHB-T–carbon nanotube composite films for modification of the electrical and optical properties

Free-standing polymer/multiwalled carbon nanotubes composite thin films for high thermal conductivity and prominent EMI shielding

Lightweight composite materials with efficient thermal conductivity (TC) and high electromagnetic interference (EMI) shielding effectiveness (SE) are of paramount importance for a wide range of applications such as electronics, aerospace, and stealth technology. In this work, lightweight, flexible, and free-standing poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)/multiwalled carbon nanotube (MWCNT) composite thin films are fabricated by a single-step, solution casting method. Fabricated PVDF-HFP/MWCNT composite thin films are characterized by many physicochemical techniques such as Raman spectra, Fourier transform infrared spectra, X-ray diffractometer, and high-resolution transmission electron microscope. The resulting composite thin film exhibits a TC of 1.1 Wm−1K−1 at room temperature. Further analysis shows that the TC of the composite film is increased up to 1.8 Wm−1K−1 at 100 °C. As fabricated flexible and free-standing composite thin film (thickness ∼ 150 µm) exhibit an excellent EMI SE of ∼ 36 dB in the X-band region (8.2–12.4 GHz) at just 15 wt. % loading of MWCNT. The outstanding EMI shielding and high TC of PVDF-HFP/MWCNT composite films are attributed to the homogenous distribution and well-connected network of MWCNT within the polymer matrix, forming a conductive network throughout the composite film.

Facile preparation of OHB-T–carbon nanotube composite films for modification of the electrical and optical properties

Facile preparation of OHB-T–carbon nanotube composite films for modification of the electrical and optical properties

Effect of Weight Ratio of Graphene Oxide and Carbon Nanotubes on Electrochemical Performance of Planar On-Chip Micro-Supercapacitors

With the wide popularization of 5 G network, the application of miniaturized electronic equipment is being gradually developed, but limited by energy storage technology. Micro-supercapacitors (MSCs) have become the possible direction to solve this problem because of their unique properties. Graphene oxide and carbon nanotubes are very suitable materials for preparing MSCs. However, graphene oxide will overlap due to van der Waals force, and carbon nanotubes will be entangled. In order to solve these problems, reduced graphene oxide and carbon nanotube composite films were prepared by liquid-air interface self-assembly and hydroiodic acid reduction. Planar MSCs with weight ratios of 5:1, 10:1 and 15:1 were prepared by photolithography, and the MSCs of 15:1 show the best comprehensive performance with the area capacitance of 0.905 μF cm−2, the energy density of 0.125 nWh cm−2, the power density of 2263.31 nW cm−2, the time constant of 38 ms, and the capacitance retention of 91.2%.

Cellular-structured carbon nanotube composite films with broadband microwave absorption and shape memory

Carbon nanotube (CNT) composite films consisting of a microcellular structure are prepared by layer-by-layer deposition and phase separation processing. Polyvinyl butyral (PVB) and CNTs form a continuous network of cell walls of less than 100 nm thick and epoxy resin (EP) spheres of 4–6 μm in diameter constitute the cell cores with Ba-ferrite lamella aggregated among the cells. The layer-by-layer deposition of CNTs ensures a uniform dispersion of CNTs, and the EP spheres separate CNTs and Ba-ferrite to form a dielectric-magnetic coupling network. The resultant cell structure is conducive not only to achieve electromagnetic impedance matching but also to induce wave attenuation by multiple mechanisms. The composite film with optimal electromagnetic loss and impedance matching has a broad effective bandwidth of 11.5 GHz in microwave absorption at a thickness of only 0.3 mm, superior over most carbon-based microwave absorbing materials reported so far. In addition, the composite film also shows good thermal response for shape memory. This study provides a microcellular strategy for developing materials with light weight, thin thickness, broadband absorption, and shape memory for applications in civil and military fields.

Flexible Hf6Ta2O17@ acidified carbon nanotube composite films with enhanced interfacial interaction for high-performance supercapacitors

Recently, various transition metal oxides (TMOs) have been introduced to modify carbon nanotubes (CNTs), demonstrating great potential for high energy storage performance. Herein, we designed a novel flexible composite film based on Hf6Ta2O17 (HTO) and CNTs to leverage their complementary advantages. HTO nanocrystals were prepared by the polymer derived ceramics (PDC) method, which could be uniformly distributed and firmly embedded on the surface of carboxy functionalized single-wall carbon nanotubes (SWCNTs). More importantly, we developed a new way to enhance the interfacial interaction between the TMOs and the carbon materials to optimize the energy storage performance of the resulting composites. Finally, the composite supercapacitor showed the maximum specific capacitance of 5862.5 mF cm−2 at the current density of 5 mA cm−2 with a potential window of 2 V, which was much higher than those obtained from the two materials alone. Furthermore, the synergistic effect was confirmed to efficiently reduce the work function of the composite as well as the energy required by the electronic transition. Our results implied that the composite materials based on TMO and carbon materials (e.g. nanotubes or graphene), including the flexible HTO@ acidified carbon nanotube composite film, holds real promise for the applications as promising energy storage materials.

Silica nanochannel array on co-electrodeposited graphene-carbon nanotubes 3D composite film for antifouling detection of uric acid in human serum and urine samples

The present work reports a rapid and convenient electrochemical method for highly sensitive detection of uric acid (UA) by integration of vertically-ordered mesoporous silica film bearing amino groups (NH2-VMSF) and three-dimensional graphene-carbon nanotubes (3DG@CNT) composite film. 3DG@CNT and NH2-VMSF are successively modified onto the glassy carbon electrode (GCE) surface through a rather simple two-step controllable electrochemical deposition method. Arising from the large specific surface area, excellent electrocatalytic activity, and favorable mass transfer, 3DG@CNT co-electrodeposited onto the GCE surface could not only significantly improve the electrode performance, but also provide oxygen-containing groups for further functionalization. NH2-VMSF prepared by co-condensation approach using electrochemically assisted self-assembly method, possesses uniform pore size (∼2 nm in diameter) and positively charged surface, showing pronounced anionic permselectivity. Thanks to the electroactive 3DG@CNT inner layer and electrostatically preconcentrated NH2-VMSF outer layer, the proposed NH2-VMSF/3DG@CNT/GCE displays outstanding analytical performance towards UA with a wide linear range (0.1∼50 μM), a high sensitivity (1.66 µA·μM−1) and a low limit of detection (6.8 nM). Furthermore, considering the inherent anti-fouling property of NH2-VMSF, direct analysis of UA in human serum and urine samples is achieved with satisfactory recoveries.

Improved electrothermal performance of graphene-carbon nanotubes composite films utilizing AgNWs coating method

A safe and high-performance electrothermal heater needs a lower operating voltage to produce heat for a long time and with high efficiency. The graphene-carbon nanotubes composite films and the AgNWs (siliver nanowires) dispersions were prepared and the AgNWs were successfully coated on to the composite films. The electrothermal performance of composite films with different carbon nanotubes (CNTs) contents, polymer additions and coating AgNWs were investigated. The maximum heating temperature decreases when the content of the polymer increases. In addition, the maximum temperature increases with the addition of CNTs. The sheet resistance gradually decreases with improving AgNWs coated amount and the sheet resistance changes little with the bending times on the whole. The microstructure of composite films coated with AgNWs revealed that AgNWs filled the holes on the surface of the composite films. Besides, the electrothermal efficiency, heating rate and cooling rate were significantly improved. For the electrothermal performance of the composite film coated with AgNWs only on the contact surface, the electrothermal efficiency, heating rate and cooling rate were also significantly improved compared with those of the composite films without an AgNWs coating. Therefore, composite film coating with AgNWs is one effective method to significantly improve the electrothermal performance for Gr composite film.

Improved Electrical and Thermal Conductivities of Graphene–Carbon Nanotube Composite Film as an Advanced Thermal Interface Material

Thermal management has become a crucial issue for the rapid development of electronic devices, and thermal interface materials (TIMs) play an important role in improving heat dissipation. Recently, carbon−based TIMs, including graphene, reduced graphene oxide, and carbon nanotubes (CNTs) with high thermal conductivity, have attracted great attention. In this work, we provide graphene−carbon nanotube composite films with improved electrical and thermal conductivities. The composite films were prepared from mixed graphene oxide (GO) and CNT solutions and then were thermally reduced at a temperature greater than 2000 K to form a reduced graphene oxide (rGO)/CNT composite film. The added CNTs connect adjacent graphene layers, increase the interlayer interaction, and block the interlayer slipping of graphene layers, thereby improving the electrical conductivity, through−plane thermal conductivity, and mechanical properties of the rGO/CNT composite film at an appropriate CNT concentration. The rGO/CNT(4:1) composite film has the most desired properties with an electrical conductivity of ~2827 S/cm and an in−plane thermal conductivity of ~627 W/(m·K). The produced rGO/CNT composite film as a TIM will significantly improve the heat dissipation capability and has potential applications in thermal management of electronics.

N-type silver ammonia-polyethyleneimine/single-walled carbon nanotube composite films with enhanced thermoelectric properties.

Carbon nanotubes and their composite thermoelectric (TE) materials have significant advantages in supplying power to flexible electronics due to their high electrical conductivity, excellent flexibility, and facile preparation technology. In this work, stable n-type silver ammonia-polyethyleneimine/single-walled carbon nanotube ([Ag(NH3)2]+-PEI/SWCNT) composite films were facilely prepared by solution blending and vacuum-filtration methods. The results demonstrate that light silver ammonia doping optimizes the carrier concentration and carrier mobility of the composite film, and a maximum power factor (PF) of [Ag(NH3)2]+-PEI/SWCNT of 91.9 μW m-1 K-2 was obtained, which is higher than that of PEI/SWCNT (70.0 μW m-1 K-2). Furthermore, when the composite films were reduced by the NaBH4 solution, the Seebeck coefficient and the PF value were further increased to -45.5 μV K-1 and 115.8 μW m-1 K-2, respectively. For demonstration, a maximum output voltage of 13.8 mV and output power of 492 nW were achieved using a three p-n junction-based TE device constructed by [Ag(NH3)2]+-PEI/SWCNT at a temperature difference of 50 K. Thus, this study provides a metal complex ion doping strategy to improve thermoelectrical properties and air stability of the PEI/SWCNT composite films, which have potential applications in flexible electronics.

Preparation and structure dependent thermoelectric properties of flexible N-type nanostructured silver(I) selenide/multi-walled carbon nanotube composite film

Herein, multi-walled carbon nanotube/silver selenide (MWCNT/Ag2Se) composite films are prepared with a simple solvothermal method, and their thermoelectric (TE) properties are measured. The composite with a 1 wt% of MWCNT shows an enhanced power factor due to the improvement in electrical conductivity. In addition, the synthesized MWCNT/Ag2Se composites are prepared with either an embedded or grafted structured composite. A reduced thermal conductivity of ∼0.84 W/m·K was obtained with the MWCNT-grafted nanostructure Ag2Se composite due to the strong phonon scattering. The maximum figure of merit (ZT) of the composite sample was achieved with the grafted-MWCNT/Ag2Se composite film containing 1 wt% MWCNT. A thermoelectric generator (TEG) prototype composite with 6 strips was designed and the prepared TEG generated a maximum output voltage and output power of ∼29.2 mV and ∼3.8 μW, respectively, at a temperature difference (ΔT) of ∼40 K. The prepared TE composite can be an important component in carbon-based hybrid inorganic flexible TE composites with enhanced TE properties.

Fabrication and Evaluation of Basil Essential Oil-Loaded Halloysite Nanotubes in Chitosan Nanocomposite Film and Its Application in Food Packaging.

Increasing health concerns regarding the use of plasticware have led to the development of ecofriendly biodegradable packaging film from natural polymer and food additives. In the present study, basil essential oil (BEO) loaded halloysite nanotubes (HNTs) composite films were synthesized using a solution casting method. The effects of BEO and nanotube concentration on the mechanical, physical, structural, barrier, and antioxidant properties of films were evaluated. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) demonstrated well-dispersed HNTs and BEO in tailored composite films. The addition of BEO in Chitosan (Ch) film caused darkening of the film color; furthermore, the incorporation of HNTs in varied concentrations increased opaqueness in Ch/BEO film. The Ch/BEO film, upon adding HNTs 5-30 wt%, exhibited a corresponding increase in the film thickness (0.108-0.135 mm) when compared with the Ch/BEO film alone (0.081 mm). The BEO-loaded HNTs composite films displayed reduced moisture content and characteristic barrier and UV properties. The Ch/BEO film with 15 wt% HNTs was found to have enhanced antioxidant activity. The Ch/BEO/HNTs composite also managed to prevent broccoli florets from losing weight and firmness during storage. The enhanced barrier and antioxidant qualities of the nanocomposite film suggest its potential application in the food processing and packaging sector. This is the first ever report on the fabrication of nanocomposite film using BEO and HNTs for food packaging. The low production cost and ecofriendly approach make the film acceptable for further research and commercialization thereafter.

Processable Potassium-Carbon Nanotube Film with a Three-Dimensional Structure for Ultrastable Metallic Potassium Anodes.

K metal holds great promise as the ultimate anode candidate for K-ion batteries because of its high theoretical capacity and low operating potential. However, due to its high viscosity and poor mechanical processability, it remains challenging to manufacture potassium anodes with precise parameters by a simple and executable method. In this work, a high-performance potassium-carbon nanotubes (K@CNTs) composite film electrode with a three-dimensional (3D) skeleton and superior processability is prepared by simply incorporating CNTs into molten potassium. The in situ potassiation reaction between CNTs and molten K formed potassium carbide (KC8) so as to obtain a solid-liquid mixture, which can reduce the surface tension of molten potassium and promote the preparation of the K@CNTs film electrode. The composite electrode can be molded into a variety of shapes and thicknesses in accurate dimensions. The porous, well-conducting CNTs act as a 3D skeleton uniformly distributed in the K metal, providing adequate surface and space to accommodate and attract K metal, thereby inhibiting the growth of the potassium dendrites and the volume expansion upon cycling. As a result, the K@CNTs composite anode exhibits excellent cyclability and rate capability in both symmetric and full cells. The superior processability and excellent electrochemical performance make this composite an ideal anode candidate for commercial applications in potassium metal batteries.

Preparation and characterization of chitosan/halloysite nanotubes composite film with ethylene scavenging and gas resistance for active food packaging

AbstractIn this study, the halloysite nanotubes (HNT) were incorporated into chitosan (CS) to prepare CS/HNT composite film by solution‐casting method. Different HNT contents were studied in relation to the morphological, optical, mechanical, barrier and thermal properties of CS/HNT composite films. After incorporation of HNT, the CS/HNT composite films showed improvement in UV light shielding, barrier against water vapor and oxygen, mechanical strength and thermal stability as well as achievement of ethylene scavenging property. Especially, when 5 wt% HNT were added, more homogenous distribution of HNT in CS matrix was observed by SEM, resulting in 169.9% increase in tensile strength, 52.94% decline in oxygen permeability and 4.07 times enhancement in the ethylene scavenging capacity at 100 kPa pressure compared with pure CS film. Moreover, the obtained film with 5 wt% HNT effectively maintained the freshness of bananas and cherry tomatoes under ambient conditions. This study demonstrated that the CS/HNT composite films could be used as active food packaging material to extend the shelf‐life of fresh fruits and vegetables.

Bicontinuous, High-Strength, and Multifunctional Chemical-Cross-Linked MXene/Superaligned Carbon Nanotube Film.

Lightweight, thin, large-area, and ultraflexible chemical-cross-linked MXene/superaligned carbon nanotube composite films with a bicontinuous structure are manufactured. The films exhibit high mechanical strength, good electrical conductivity, hydrophobicity, and oxidation stability, as well as wearable multifunctionalities involving electromagnetic interference (EMI) shielding, electrothermal conversion, and photothermal antibacterial performance. An X-band EMI shielding effectiveness (SE) of 24 to 70 dB at the thickness of 8 to 28 μm and an SE of more than 60 dB in ultrabroadband frequency range of 8.2-40 GHz are accomplished. A surface specific SE of 122 368 dB·cm2·g-1 is achieved, significantly outperforming other typical shields reported. The good electro-/photothermal performance of the films leads to high-efficiency deicing and antibacterial performance. Combined with the efficient and scalable manufacturing approach, the multifunctional wearable bicontinuous films show great potential for applications in wearable devices, defense, antibacterials, and the Internet of Things.