Nanotube Composite Films Research Articles

Electrodeposition of Ag/CNT Composite Films from Iodide Plating Baths

Ag/carbon nanotube (CNT) composite films were prepared by electrodeposition from non-cyanide baths. An iodide bath and multiwalled CNTs were used. The stability of the iodide bath under ambient conditions at various pH levels was examined, along with the changes in visual appearance, pH, and triiodide ion (I3−) concentration. The electrodeposition was conducted under galvanostatic conditions using iodide baths with and without CNTs. The microstructure of the Ag and Ag/CNT composite films was characterized, and the hardness, electrical conductivity, and coefficient of friction of the films were measured. The iodide bath was stable at higher pH levels under ambient conditions. The obtained Ag/CNT composite films exhibited a compact structure, and CNTs were homogeneously distributed in the interior of the deposited Ag matrix. The CNT content in the deposits increased with increasing CNT concentration in the plating bath. The hardness of the Ag/1.2 mass%-CNT composite film was 63.2 HV, which was slightly greater than that of the Ag film (60.4 HV). The resistivity of the composite film was 1.9 μΩ cm, which was slightly higher than that of the pure Ag film (1.8 μΩ cm). The coefficient of friction of the composite film was lower than that of the Ag film.

Electrical, mechanical, and optical changes in MWCNT-doped PMMA composite films

In this study, we report the preparation of poly (methyl methacrylate)/multi-walled carbon nanotube (MWCNT) composite thin films by simple and efficient solution mixing and ultrasonic method and the electrical, optical, and mechanical characterizations. Scattered light intensity ( I sc), tensile modulus ( E), and surface conductivity ( σ) of these composites have increased with the addition of MWCNT into the composite. The observed behavior in electrical, optical, and mechanical properties of the poly (methyl methacrylate)/MWCNT composites was interpreted by site and classical percolation theory. The optical mechanical and electrical percolation thresholds of poly (methyl methacrylate)/MWCNT composites were determined as φ op = 3 wt%, φ m = 0 wt%, and φσ = 5 wt%, respectively. The optical ( t op), mechanical ( t m), and electrical ( t σ) critical exponents were calculated as 2.23, 0.43, and 0.11, respectively. Both the tensile modulus and tensile strength of poly (methyl methacrylate)/MWCNT composites were increased with increasing MWCNT content until it reaches to 10 wt%. However, above φ = 10 wt%, the mechanical properties of the composites were decreased due to the aggregation of MWCNTs, while the toughness does not show a significant change until φ = 10 wt% MWCNT content, whereas it was decreased above this value.

Highly Selective Simultaneous Detection of 1,4-Dihydroxybenzene and 1,2-Dihydroxybenzene Based on CdSe Quantum Dots-Multiwalled Carbon Nanotube Composite

A new electrochemical sensor based on CdSe quantum dots-multiwalled carbon nanotube composite film (CdSeQDs-cMWCNTs) was developed for highly selective simultaneous determination of 1,4-dihydroxybenzene (hydroquinone, HQ) and 1,2-dihydroxybenzene (catechol, CC) in 0.1 M phosphate buffer solution (pH 7.4). CdSeQDs-cMWCNTs/GCE exhibited two well-distinguished anodic peaks with large currents for simultaneous detection of HQ and CC in comparison with bare GCE and cMWCNTs/GCE. Furthermore, CdSeQDs-cMWCNTs/GCE has an excellent anti-interference ability for the detection of HQ and CC in the presence of some inorganic compounds and phenol derivatives. Under the optimized condition, CdSeQDs-cMWCNTs/GCE showed wide linear responses from $0.5~\mu \text{M}$ to $110~\mu \text{M}$ for HQ, and from $0.5~\mu \text{M}$ to $110~\mu \text{M}$ for CC, with the detection limits of $0.35~\mu \text{M}$ and $0.25~\mu \text{M}$ , respectively. CdSeQDs-cMWCNTs/GCE was successfully applied to the simultaneous determination of HQ and CC in tap water with satisfactory recovery.

Facile production of natural silk nanofibers for electronic device applications

Natural silk nanofibers (SNFs) have been attracted more attentions in flexible functional devices and biomaterials. However, its mass production and complex fabrication process remains challenging. In this study, we successfully developed a new physical-chemical strategy to fabricate natural SNFs with high yield (~87%). The natural SNFs performed an excellent dispersion in aqueous solution with uniform diameter (approximately 280 nm) and 10–30 μm length. The high-flexible natural SNFs/single-wall carbon nanotube (CNTs) composite films were prepared to evaluate their potential in electronic devices. The composite films exhibited remarkable dimensional stability, chemical durability, and Young's modulus (498.7 ± 64.4 MPa). Furtherly, the composite films also presented excellent electrical heating properties and potential utilities in electronics. These natural SNFs/CNTs composite films with high-mechanical and electrical features offer new starting materials for bioelectronics devices applications, such as conductive wire, electronical heater, and capacitor.

Functionalized Multi-Walled Carbon Nanotubes and Micro Cellulose Reinforced Poly (Vinyl Alcohol) Hybrid Composite Films: Characterization and Reprocessing Performance

The aim of this research paper was to investigate the synergetic effect of micro cellulose and multi-walled carbon nanotubes (MWCNTs) combination on physicochemical, mechanical and reprocessing performance of Poly (Vinyl Alcohol) hybrid composite films. The hybrid composite films production was carried out by the solution casting method, and the reprocessed films were produced using defective (torn, faulty) films from primary production by the same method. The combined use of MWCNTs and micro cellulose improved the hydrophobicity approximately 85% in ratio. After the reprocessing, decreased intensities of the peaks in the FTIR and Raman results confirmed the reduced molecular interaction between all components of the hybrid composite film, moreover, SEM and TEM revealed the negative defects such as agglomeration which caused mechanical strength decrease. The tensile strength of PVA hybrid composite films loaded cellulose/MWCNTs, reached 97 MPa strength value and elongation at break decreased to 33% according to the neat PVA film. The study results revealed that hybridization had a remarkable impact on improving characteristic properties of composite films and reprocessing process might have been compatible with solution casting method.

Water-stable natural silk nanofibril composite films for electrical devices

Natural silk nanofibrils (SNF) have received extensive interest for functional devices. However, SNF materials are not stable in water, limiting their use in aqueous or humid environments. We explored the possibility of improving mechanical property of SNF films using regenerated silk fibroin (RSF) to form a homogeneous SNF@RSF nanocomposite. RSF treatment had a significant effect on water-stability and mechanical property of the SNF films. When soaked in water, the SNF films exhibited poor wet strength, whereas the SNF@RSF films stabilized by 1.0 wt% RSF retained 11.07 MPa wet strength. Furthermore, SNF/carbon nanotube (CNT) composite films were fabricated for electrical devices. The SNF/CNT@RSF films stabilized by 1.0 wt% RSF were stable in water and showed 11.25 MPa wet strength. The SNF/CNT@RSF films showed stable electrical conductivity and electrical heating performance, even after 20 washing cycles. This developed approach provides new options to produce SNF devices that are stable in wet conditions.

Reflective SPR Sensor for Simultaneous Measurement of Nitrate Concentration and Temperature

In this paper, a reflective fiber optic sensor based on surface plasmon resonance (SPR) was proposed to measure nitrate concentration and temperature simultaneously. The sensor adopted reflective structure, and used gold film as metal film for exciting SPR. Then, Cu-nanoparticles/carbon nanotubes composite film was used as sensitive material to measure nitrate concentration, and it was coated on the surface of the gold film by the dip coating method. Finally, polydimethylsiloxane was coated on part of the sensing probe to produce two independent resonance dips in the output spectrum. When the nitrate concentration and temperature changed, the two resonance dips would all move, but with different sensitivities. By monitoring the wavelength shifts of the two dips, the nitrate concentration and temperature could be measured simultaneously with using the dual-wavelength matrix method. Experimental results demonstrated that the measurement sensitivity of the nitrate concentration could reach 3.25 nm/lg[M], and the temperature measurement sensitivity was −2.02 nm/°C. Moreover, the sensor had high-mechanical strength and was easy to package, which could be applied to remote measurement field.

Development of voltammetric sensor based on polyimide-MWCNT composite membrane for rapid and highly sensitive detection of paracetamol

In this work, for low level detection of paracetamol (PA) a voltammetric sensor was obtained. Polyimide-multiwall carbon nanotube (PI-MWCNT) composite film was used for modification of platinum (Pt) electrode as selective membrane. Firstly, this PI-MWCNT film was synthesized with 2,5-diaminopyridine (DAP), 4,4′-oxydiphthalic anhydride (ODPA) and MWCNT as a reinforcement by thermal imidization technique. The morphology, micro and chemical structures of the obtained composite film were studied by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and thermal analysis techniques. Then, the paracetamol sensor was prepared via the modification of Pt electrode with prepared PI-MWCNT composite film. Pt electrode was modified by coating with prepared PI-MWCNT composite film. Modified Pt electrode was used as PA sensor due to its selective membrane property in the presence of interfering substances for the electrochemical detection of PA. Electrochemical behaviour of paracetamol at the polyimide film modified Pt electrode was obtained by differential pulse voltammetry (DPV) and cyclic voltammetry (CV) method. It has shown that the modified electrode exhibits remarkable repeatability and precision in analytical paracetamol response as compared with other modified paracetamol electrodes. Comparing the responses of modified electrode with the unmodified Pt electrode, selectivity, sensitivity and stable responses significantly enhanced. A linear calibration plot having a correlation coefficient of 0.997 was obtained in the concentration range from 0.3 to 1.8 mM paracetamol. A linear calibration plot for low concentration area having a correlation coefficient of 0.999 was obtained in the concentration range from 0.002 to 0.05 mM paracetamol. Detection limit (LOD) and quantitative limit (LOQ) for paracetamol detection of PI-MWCNT modified electrode were calculated as 0.002 mM and 0.006 mM respectively. In addition, the presented method was applied for determination of PA in commercial tablets. The recovery efficiency of the PI modified electrode was obtained range of 96% and 102% for three different tablets. As a result; a simple, rapid, low cost, repeatable method showing good accuracy and precision (99.4%) has been developed for the selective and sensitive determination of paracetamol by prepared PI-MWCNT composite film modified electrode.

Electrochemically self-doped WO3/TiO2 nanotubes for photocatalytic degradation of volatile organic compounds

In this study, an electrochemically self-doped WO3/TiO2 nanotubes (R-WO3/TNTs) composite film was developed for the photocatalytic degradation of waste gas. The doping of oxygen vacancies (OVs) into the heterojunction of WO3/TNTs was conducted by a simple electrochemical approach, by which the quantity and distribution of OVs on surface as well as bulk were tailored with respect to the applied cathodic potential and the duration of the treatment. With an increase of applied cathodic potential as well as the duration, the quantity of OVs on WO3/TNTs was observed to be consistently raised, while those presented in the surface were raised initially and further showed a plateau trend as the duration extended at a fixed potential. The incorporation of OVs into WO3/TNTs enhanced the charge-transport resistance and reduced the electron-hole recombination, thereby showed an enhanced photocatalytic performance. The R-WO3/TNTs prepared by the electrochemical polarization process at −1.4 V (vs SCE) exhibited a 12 times higher photo-current density and obviously, an enhanced efficiency in the photocatalytic degradation of VOCs with a prolonging photostability compared to that of the pristine WO3/TNTs, under a simulated solar light irradiation. The single-time purification trial demonstrated the effectiveness of the R-WO3/TNTs composite in treating the VOCs for the practical application.

Carbon nanotubes enhance flexible MXene films for high-rate supercapacitors

MXenes are 2D transition metal carbides or nitrides with high electrical conductivity that have attracted great attention as promising electrode materials that supersede carbon-based material designed for supercapacitors. However, the aggregation and self-restacking of MXene 2D nanosheets limit their high-rate performance. In this work, flexible and conductive Ti3C2Tx MXene/carbon nanotubes (CNTs) composite film was prepared through a simple vacuum filtration of the Ti3C2Tx MXene and CNTs suspension mixture. The CNTs integrated MXene nanosheets can effectively prevent the restacking while creating fast ion transport channels for enhanced capacitance. The designed films exhibit excellent performance as supercapacitor electrodes with high capacitance of 300 F g−1 at 1 A g−1 with superior rate performance of 199 F g−1 even at 500 A g−1, together with excellent cyclic stability of 92% capacitance retention after 10000 cycles at 20 A g−1. The excellent workability demonstrates potential application of the system for flexible, portable and highly integrated supercapacitors.

Preparation of electrospun poly(acrylic acid)/multiwalled carbon nanotubes composite nanofiber for glucose detection

In this study, poly(acrylic acid) and multiwalled carbon nanotubes (PAA/MWNTs) composite nanofiber thin film was prepared on fluorine doped indium tin oxide–coated glass substrate through electrospinning method. The electrospun PAA/MWNTs nanofiber thin film was modified with layer–by–layer (LbL) self–assembled multilayers of glucose oxidase (GOD) and poly(dialyldimethylammoniumchloride) (PDADMAC) prior to employ for glucose detection. The obtained nanofiber thin film was characterized by scanning electron microscopy and electrochemical impedance spectroscopy. The prepared nanofibers thin film shows a good potential for detection of glucose at constant applied potential through an electrochemical method.

A novel flexible UV-cured carbon nanotube composite film for humidity sensing

A new flexible resistor-type humidity sensor was developed based on UV-cured carbon nanotube composite film as humidity-sensing material. Carbon nanotubes (CNTs) were firstly mixed with UV-curable resin via ball-milling. Simply by spin-coating of this mixture on flexible interdigitated electrode and subsequent UV-curing, a flexible humidity sensor based on UV-cured CNTs composite film was thus fabricated. With the utilization of UV-curing technology, this fabricating strategy is rather simple, highly efficient (accomplished in several minutes), cost-effective, and environmental-friendly (no organic solvent). The effect of the CNTs content, the nature of the UV-curable resin as well as their ratios on the humidity-sensing performance was systematically investigated. Under optimized conditions, the UV-cured CNTs composite film showed remarkable sensing performance over a wide humidity span from 6% to 84%. In addition, the as-prepared CNTs composite film exhibited small hysteresis and fast response. Moreover, good repeatability and long-term stability was demonstrated. This work offers a novel, economical and promising way to fabricate humidity sensors considering the facile, efficient and green preparation strategy and outstanding sensing properties.

Facile fabrication of BiVO4 modified TiO2 nanotube film photoanode and its photocathodic protection effect on stainless steel

A BiVO4/TiO2 nanotube composite film was fabricated by anodization and low temperature solvothermal reaction for photocathodic protection. The results showed that after modifying the TiO2 nanotube film with BiVO4 nanoparticles, the light absorption of the BiVO4/TiO2 composite film was extended to the visible region. The photocurrent density of the composite film reached 271 μA cm−2, and was 8.5 times higher than that of the TiO2 film. Under white light irradiation, the composite film made the potential of the coupled 403 stainless steel in a 0.5 M NaCl solution drop by 520 mV, showing an effective photocathodic protection effect.

A flexible NO2 gas sensor based on polypyrrole/nitrogen-doped multiwall carbon nanotube operating at room temperature

A flexible NO2 gas sensor based on a polypyrrole/nitrogen-doped multi-walled carbon nanotube (PPy/N-MWCNT) composite film was successfully prepared on PI substrates using a combined in situ self-assembly and annealing treatment method. After annealing at 350 °C, the gas sensor exhibited a high response of 24.82% ((Rg−Ra)/Ra×100%) under 5 ppm of NO2, which is 44.12 times greater than that of the unannealed sensor. The PPy/N-MWCNT gas sensor exhibited excellent repeatability, remarkable selectivity, good long-term stability, and acceptable flexibility. Furthermore, the effect of the relative humidity on the gas sensing properties was examined. The excellent gas sensing performances of the sensor were attributed to the enriched adsorption sites due to degradation of the amount of stacked PPy structures on the surface of the N-MWCNTs after the annealing treatment. The results demonstrated that PPy/N-MWCNT composite films are highly promising for potential applications in the field of NO2 gas sensing.

A flexible tactile sensor integrated with carbon black/carbon nanotube composite film and flexible printed circuit

In this study, two kinds of composite films, carbon black (CB) and carbon nanotube (CNT) composite films, were fabricated and integrated with flexible printed circuit (FPC) for the flexible tactile sensor. CB and CNT with high compressive strength and low resistivity were immersed into the tissue paper as the sensing materials. The flexible tactile sensors were fabricated by sandwiching the CB/CNT composite film with FPC between two thin polydimethylsiloxane sheets. The tactile sensor is operated by the contact resistance change between CB/CNT composite film and FPC electrode by the different applied force. The measurements of the sensitivity, response time and stability of the fabricated tactile sensors were carried out. The fabricated CB composite film tactile sensor exhibits the sensitivity of 5.05 × 10−2 kPa−1 in the range below 20 kN m−2, the response time of 10 ms, and with the high stability of the loading and unloading pressure.

Nanowire Array-Coated Flexible Substrate to Accommodate Lithium Plating for Stable Lithium-Metal Anodes and Flexible Lithium-Organic Batteries.

Although lithium metal is an ideal anode with high theoretical capacity, Li dendrite formation and volume change have limited its application. We report a vertical polyaniline nanowire-coated carbon nanotube (CNT/PANI) composite flexible electrode on which Li could be homogeneously deposited to obtain a CNT/PANI@Li anode. In the composite, CNT/PANI acted as a host matrix with well-distributed Li ion flux attributed to high electroactive surface area, thereby effectively suppressing the Li dendrite. Compared with the pure CNT electrode, the CNT/PANI electrode presented low overpotential and stable long-term cycling with much less fluctuant stripping/plating profiles. The potential application of CNT/PANI@Li in all-flexible full cells was demonstrated by combining flexible organic poly(2,5-dihydroxyl-1,4-benzoquinonyl sulfide)/carbon nanotube (PDHBQS/CNT) composite films, in which the cathode achieves an eminent performance of 120 mA h g-1 at 50 mA g-1. Furthermore, pouch batteries with good flexibility were tested successfully, which demonstrated a promising future for all-flexible and high-performance Li-metal batteries.

Expanding the potential window of aqueous electrochemical capacitors with binder-free electrostatically sprayed manganese oxide composite cathode films

In this study, three binder-free manganese oxide-carbon nanotube (MnOx-CNT) composite films were synthesized using electrostatic spray deposition (ESD) and evaluated as electrochemical capacitor (EC) electrodes in aqueous media. The MnOx-CNT 9-1 composition exhibited superior electrochemical performance as compared to both the pristine MnOx and MnOx-CNT 8-2 composite films, exhibiting a high specific capacitance of 281 F g−1 in addition to excellent rate handling and cyclability. In order to investigate the practical viability of the MnOx-CNT 9-1 electrodes, a comprehensive two-electrode analysis was performed using activated carbon (AC) counter electrodes for different mass ratios to obtain optimal energy-power trade-off. The asymmetric capacitor with the AC electrode with a mass 2.6 times that of the MnOx-CNT 9-1 electrode exhibited the best energy-power characteristics reaching a maximal gravimetric energy density of 30.3 Wh kg−1; the excellent electrochemical performance of the asymmetric capacitor is attributed to the wider cell voltage of 2V as well as the high gravimetric capacitance of the ESD- based MnOx-CNT composite cathode.

High Performance Polymer Thermoelectric Composite Achieved by Carbon-Coated Carbon Nanotubes Network

Poly(3,4-ethylenedioxythiophene)poly(styrenesulfonate)/carbon nanotube (PEDOT:PSS/CNTs) composite films have been demonstrated to offer an excellent thermoelectric performance. In this work, p-type thermoelectric films prepared by a simple dipping coating process based on the carbon-coated carbon nanotubes (C-CNTs) continuous network are investigated. The highest power factor obtained in this work is 504.8 μW/mK2 (at 300 K) due to the relatively high electrical conductivity and Seebeck coefficient. The excellent TE properties of the C-CNTs/PEDOT:PSS composite film are attributed to the interfacial carrier scattering introduced by the unique structure. Composite materials based on a continuous network would open up new opportunities to develop high performance organic thermoelectric materials.

Characterization of Polyaniline/Single-Walled Carbon Nanotube Composite Films Prepared by Plasma Polymerization

Characterization of Polyaniline/Single-Walled Carbon Nanotube Composite Films Prepared by Plasma Polymerization

Flexible and free-standing thermoelectric devices prepared from poly(vinylidene fluoride-co-hexafluoropropylene)/graphite nanoplatelet/single-walled carbon nanotube composite films

In this study, poly(vinylidene fluoride-co-hexafluoropropylene)/carbon composite films with enhanced thermoelectric performance are prepared. A hybrid filler of graphite nanoplatelets (GNPs) and single-walled carbon nanotubes (SWNTs) increase the electrical conductivity as a bridge between neighboring GNPs in the carbon hybrid films. The improved electrical conductivity is due to the purification process performed in an acid solution, which effectively removes the amorphous carbon, additives, and impurities in the carbon fillers. The Seebeck coefficient of the composite films is similarly maintained at approximately 40 μV/K owing to the intrinsic properties of the material. The calculated power factor is considerably increased to approximately 14 μW/mK2 owing to purification of the SWNTs, which is twice the value of the highest value reported value for freestanding-type thermoelectric materials based on polymer/carbon composites.