Polyaniline Carbon Nanotubes Research Articles

Selective Reduction of Nitrite to Nitrogen by Polyaniline-Carbon Nanotubes Composite at Neutral Ph

Selective Reduction of Nitrite to Nitrogen by Polyaniline-Carbon Nanotubes Composite at Neutral Ph

Simultaneous Adsorption and In-Situ Selective Reduction of Nitrite to Nitrogen by Polyaniline-Carbon Nanotubes Composite at Neutral Ph

Simultaneous Adsorption and In-Situ Selective Reduction of Nitrite to Nitrogen by Polyaniline-Carbon Nanotubes Composite at Neutral Ph

Selective Reduction of Nitrite to Nitrogen by Polyaniline-Carbon Nanotubes Composite at Neutral Ph

Selective Reduction of Nitrite to Nitrogen by Polyaniline-Carbon Nanotubes Composite at Neutral Ph

Enhancing Seebeck coefficient and electrical conductivity of polyaniline/carbon nanotube–coated thermoelectric fabric

In this work, flexible thermoelectric fabrics, polyester/yarn fabrics coated with polyaniline/carbon nanotube (PANI/CNT) nanocomposite, were fabricated by sequential processing: (I) polyaniline/carbon nanotube nanocomposites preparation by a one-step in-situ polymerization and (II) dip coating of a mixture solution of CNT-doped PANI on a polyester/yarn fabric. Nanocomposites were synthesized with various CNT content (0.5, 2.5, 5, and 10 wt%) and characterized using different methods. The Seebeck coefficient and electrical conductivity measurements were used to determine their thermoelectric properties. The results revealed significant improvement in both electrical conductivity and the Seebeck coefficient with the addition of CNT. The electrical conductivity increased from 0.011 to 0.1345 S/cm with the increment of CNT from 0.5 to 10 wt%. The highest Seebeck coefficient of 11.4 μV/K was observed for the sample containing 5 wt% CNT at 338 K where the maximum power factor of 1.598×10−3 μWm−1K−2 was obtained for the fabric coated with nanocomposite containing 10 wt% CNT.

The Nail Penetration Behaviour of Carbon Nanotube Composite Electrodes for Energy Storage

The high surface area, electrical and mechanical properties of carbon nanotube (CNT) composites has rendered them promising candidates for structural power composites. Nevertheless, it is important to understand their mechanical behaviour before they are applied in energy storage devices amid the safety concerns. This work explores the nail penetration behaviours of supercapacitor specimens consisting of CNT electrodes and pseudocapacitor specimens with carbon nanotube-polyaniline (CNT/PANI) electrodes. Specimens with and without electrolyte were tested. The dry cells without electrolyte follow a power law behaviour, while the wet cells with the electrolyte exhibit a piece-wise nonlinear relationship. The force, voltage and temperature of the supercapacitor were recorded during the nail penetration test. No temperature change or overheating was observed after short-circuit. Moreover, electrochemical testing is performed before and after the specimen penetration. The cyclic voltammetry shows the dramatic loss of capacitance, changing the cell behaviour from capacitor to resistor-like manner. Johnson-Cook model was used to predict the nail penetration behaviour. The coefficients of Johnson-Cook model are calibrated from the experimental load-displacement curves. The finite element model predictions are in a good agreement with the experimental results.

Printed Flexible Thermoelectric Nanocomposites Based on Carbon Nanotubes and Polyaniline.

A new era of composite organic materials, nanomaterials, and printed electronics is emerging to the applications of thermoelectric generators (TEGs). Special attention is focused on carbon nanomaterials and conducting polymers, and the possibility to form pastes and inks for various low-cost deposition techniques. In this work, we present a novel approach to the processing of composite materials for screen-printing based on carbon nanotubes (CNTs) and polyaniline (PANI), supported with a dielectric polymer vehicle. Three different types of such tailor-made materials were prepared, with a functional phase consisted of carbon nanotubes and polyaniline composites fabricated with two methods: dry mixing of PANI CNT powders and in situ polymerisation of PANI with CNT. These materials were printed on flexible polymer substrates, exhibiting outstanding mechanical properties. The best parameters obtained for elaborated materials were , , and , respectively.

The mechanical and electrochemical properties of polyaniline-coated carbon nanotube mat

The measured capacitance, modulus and strength of carbon nanotube-polyaniline (CNT-PANI) composite electrodes render them promising candidates for structural energy storage devices. Here, CNT-PANI composite electrodes are manufactured with electrodeposition of PANI onto the bundle network of CNT mats produced via a floating catalyst chemical vapour deposition process. PANI comprises 0% to 30% by volume of the electrode. The composition, modulus, strength and capacitance of the electrodes is measured in the initial state, after the first charge, and after 1000 charge/discharge cycles. Electrode modulus and strength increase with increasing CNT volume fraction; in contrast, the capacitance increases with increasing PANI mass. Charging or cycling reduce the electrode modulus and strength due to a decrease in CNT bundle volume fraction caused by swelling; the electrode capacitance also decreases due to a reduction in PANI mass. A micromechanical model is able to predict the stress-strain response of pre-charged and cycled electrodes, based upon their measured composition after pre-charging and cycling. The electrodes possess up to 63% of their theoretical capacitance, and their tensile strengths are comparable to those of engineering alloys. Their capacitance and strength decrease by less than 15% after the application of 1000 charge/discharge cycles. These properties illustrate their potential as structural energy storage devices.

Enhanced electrical properties of polyaniline carbon nanotube composites: Analysis of temperature dependence of electrical conductivity using variable range hopping and fluctuation induced tunneling models

Hydrochloric acid doped polyaniline – multiwalled carbon nanotube nanocomposites are successfully synthesized by chemical in-situ polymerization and their structural, thermal, morphological and electrical properties are investigated. The synthesized PANI-MWNT composites show quite high room temperature DC electrical conductivity, very good thermal stability and a weak temperature dependence of conductivity comparable to doped polymers showing metallic conductivity. The charge transport mechanism in these nanocomposites is analyzed using variable range hopping and fluctuation induced tunneling models, and validation of these models is also carried out using the statistical methods, regression analysis and the analysis of variance. The temperature variation of electrical conductivity is found to best fit with the three-dimensional variable range hopping model. The one-dimensional nature of MWNT enhanced the charge transport in the composite materials. The present study is significant in polymer/organic materials with high mobility charge carriers for various electrical applications such as EMI shielding. The stable DC electrical conductivity observed in the PANI-MWNT composites even at high temperatures highlights the prospects of application of these composites in the fabrication of devices capable of operating at high temperatures. The multifunctional characteristics of MWNT make these composites a potential candidate for the electrical, thermal, sensing and actuating applications.

“Sweat-chargeable” on-skin supercapacitors for practical wearable energy applications

Supercapacitors (SCs) have received worldwide attention as energy devices for wearable smart systems. Biocompatibility and self-charging property of SCs require serious consideration, but the related studies are just in their infancy. Here, a “sweat-chargeable” on-skin SC using biocompatible NaCl electrolyte and freestanding polyaniline/carbon nanotube (PANI/CNT) electrodes is presented. Although the capacitance of the biocompatible SC is about half of that using conventional skin-irritated H2SO4 electrolyte, the potential window extends from 0.8 V to 1.4 V. Thus, a higher energy density can be obtained. The self-charging property is achieved by simply adding a piece of Zn foil on one electrode with silver paste, which provides energy source and maintains a super compact two-electrode configuration of SC. The sweat absorbed from human body could trigger the redox reaction between the added Zn foil and oxygen in air, resulting in the self-charging of the device to 0.652 V in 6 min. To demonstrate its wearability in real applications, a “sweat-chargeable” band is prepared that can spontaneously power a timer or a pedometer when the user is exercising. This work has made a further step in the development of biocompatible and practical wearable energy devices.

Effective electrochemically controlled removal of fluoride ions using electrodeposited polyaniline-carbon nanotube composite electrodes

The objective of this study is to improve the selective removal of fluoride ions from water using an electrodeposited polyaniline-carbon nanotube (PANI-CNT) composite electrode. The PANI-CNT electrode was successfully fabricated in a partially oxidized emeraldine form, as indicated by the cyclic voltammetry (CV) and X-ray photoelectron spectroscopy (XPS) results. The PANI-CNT composite electrode is dominated by mesopores and presents good hydrophilicity, which improves the mass transfer of ions and ensures better wettability, respectively, during electrochemically controlled separation experiments. The optimal voltage and pH for the fluoride removal are 1.6 V and 7, respectively. The fluoride removal capacity using the PANI-CNT (0.52 mmol g−1) electrode is larger than that of the carbon nanotube (CNT) (0.34 mmol g−1) electrode due to the PANI redox reactions. This finding indicates that enhanced fluoride removal from water can be achieved by incorporating PANI with CNTs. More importantly, the selectivity for fluoride over chloride using the PANI-CNT electrode significantly increases from 0.26 to 1.22, suggesting that the composite electrode incorporates fluoride rather than chloride due to the strong electronegativity of fluoride. The PANI-CNT electrode maintains good stability and reversibility for fluoride removal for four electrochemical cycles, which highlights the feasibility of the selective separation of fluoride ions via an electrochemically controlled approach.

Facile preparation of polyaniline-carbon nanotube hybrid electrodes and dependence of their supercapacitive properties on degree of carboxylation of carbon nanotubes

This paper reports on the preparation of polyaniline-carbon nanotube (PANi-CNT) hybrid electrodes via a facile electro-co-deposition method. In the process, carboxylated CNTs, which serve as counter anions in the electrodes, are incorporated into PANi. Supercapacitive properties of PANi-CNT hybrid electrodes are observed to depend on the degree of carboxylation of CNTs. Electrochemical measurements show two key results. First, the incorporation of CNTs observably improves the supercapacitive properties of PANi electrodes. Second, the CNTs with higher degree of carboxylation result in further improvement in supercapacitive properties of the hybrid electrodes. The former observation is attributed to the high electrical conductivity and large surface area of CNTs, which improve the electrical conductivities of the hybrids and facilitate the dispersion of PANi. The latter is in line with the fact that more CNTs are incorporated into the hybrids due to higher degree of carboxylation. The PANi-CNT electrodes prepared by CNTs with higher degree of carboxylation demonstrate remarkable supercapacitive performances, including high specific capacitance of 578.2 F g−1 and good rate performance. They also have superior cycling stability, showing 88.2% of capacitance retention after 10,000 cycles.

Enhanced Charge Transport and Corrosion Protection Properties of Polyaniline–Carbon Nanotube Composite Coatings on Mild Steel

We report on the synthesis and characterization of carbon nanotube (CNT)-doped polyaniline (PANI) composites for enhanced corrosion protection of steel with improved electrical properties. PANI–CNT nanocomposites were prepared through in situ polymerization of aniline in the presence of CNTs. Synthesized nanocomposites were characterized by several analytical methods such as Fourier transform infrared spectroscopy, x-ray diffraction, micro-Raman spectroscopy, and scanning electron microscopy in order to understand the structural, morphological, and molecular aspects of the composites. The doping of CNTs in PANI matrix drastically enhanced the alternating current/direct current (AC/DC) conductivities as well as the dielectric attributes and impedance spectroscopy of the composites. The anticorrosion studies of the prepared composites were performed by using open-circuit potential analysis and potentiodynamic measurements. Compared to stainless steel, PANI–CNT nanocomposites demonstrated excellent anticorrosion behavior. The obtained results showed that 25 wt.% of CNT-doped PANI composite exhibits excellent anticorrosion properties due to electron transmission and passive catalysis.

Sub-micron calcium carbonate as a template for the preparation of dendrite-like PANI/CNT nanocomposites and its corrosion protection properties

The dendrite-like polyaniline/carbon nanotube (PANI/CNT) nanocomposites have been successfully prepared through the oxidative polymerization of aniline on the surface of nanocomposites of sub-micron calcium carbonate composites and CNT, in acid aqueous solution. With calcium carbonated composing, the adherent dendrite-like PANI forms on the CNT surface. The possible mechanism is the turbulence around CNT due to the gas carbon dioxide formed by decomposition of calcium carbonate template, that leads to forming this unique composite morphology. The obtained PANI/CNT nanocomposites exhibit excellent redox capability not only in acidic but also in neutral medium due to the interfacial π-π interactions between CNT and PANI. The PANI/CNT nanocomposites are found to be easily dispersed into the aqueous waterborne acrylate-amino (AA) resin. The AA coating filled with PANI/CNT has 76 days resistance against 3.5 wt% NaCl solution at 65 °C, which is higher than 29 days for the AA coating contained PANI and much higher than 60 h for the unfilled AA coating. The superior corrosion protection mechanisms are revealed to be the “labyrinth effect” of nanocomposites and “anodic protection” of passivation film. Therefore, this strategy and nanocomposite platform may have high potential in corrosion protection area.

Single-walled carbon nanotubes–polyaniline composites: Synthesis and field-emission analysis

In this article, we report a facile synthesis and comparative analysis of field emission behavior of polyaniline (PANI)-coated as-received and annealed single-walled carbon nanotube (SWCNT) films by in-situ polymerization and ex-situ synthesis routes, respectively. Amongst all the samples, the sample prepared by in-situ polymerization method with more fraction of annealed SWCNTs in the composite gave an enhanced field emission characteristics with E to = 3 V/μm and β = 1.2 × 104 probably because of good formation of pi-pi non-covalent bonds between the SWCNTs and PANI represented by pi-pi interaction between the quinoid rings of PANI and π bond of the SWCNTs lattice. A significant increase in the threshold field is observed after annealing and doping of nanocomposite films. Field emission behavior of as-prepared nanocomposite samples are also analyzed and discussed with two PANI forms: micro-PANI particles and PANI nanofibers. It is also speculated that PANI may have helped in lowering the overall work function of the composite structure which gave an enhanced field emission. The stability of all the samples are also presented and it is analyzed that nanocomposite sample films synthesized by in-situ polymerization method showed a stability for at least 8 h. The surface morphology analysis by field emission scanning electron microscopy of nanocomposite sample films reveal an increase in SWCNTs diameter upon PANI wrapping. The high-resolution transmission electron microscopy and Raman spectra and X-ray diffraction analysis are also presented.

A 3D porous NCNT sponge anode modified with chitosan and Polyaniline for high-performance microbial fuel cell

A microbial fuel cell (MFC) is a potential bio-electrochemical technology that utilizes microorganisms to convert chemical energy into electrical energy. The low power output of MFCs remain the bottleneck for their practical applications. In this paper, a novel, biocompatible and bioelectrocatalytic composite chitosan-nitrogen doped carbon nanotubes-polyaniline (CS-NCNT-PANI) was prepared in situ on the 3D porous NCNT/sponge and applied to an MFC anode. The PANI was grafted on the CS-NCNT backbone to synthesize the ternary composite. This bioanode not only increased the active surface area and capacity but also facilitated bacterial adhesion and enrichment of microbes. Compared with the NCNT/sponge electrode, the charge transfer impedance of the ternary composite bioanode decreased from 14.07 Ω to 2.25 Ω, and the maximum power density increased from 1.4 W·m−3 to 4.2 W·m−3; meanwhile, during the chronoamperometric experiment with a charge-discharge time of 60–60 min, the cumulative charge of the composite bioanode was 18,865.8 C·m−2, which is much higher than that of the NCNT/S anode (3625.3 C·m−2). High-throughput sequencing technology revealed that the ternary composite bioanode had good biocompatibility and high diversity. Therefore, this synthesized ternary composite is a promising candidate as a capacitive and biocompatible anode material in MFC.

Facile and scalable preparation of highly porous polyvinyl chloride-multi walled carbon nanotubes-polyaniline composite film for solid-state flexible supercapacitor

Flexible and lightweight PVC-MWCNTs-PANI nanocomposite film with highly porous 3D network structure and good capacitive behavior was easily fabricated via uniform adding of Azodicarbonamide (ADC) as a foaming agent into structure of Polyvinyl chloride-Multi walled carbon nanotubes-Polyaniline composite. ADC in the composite film can be decomposed to various volatile gases under a controlled temperature, resulting in the formation of porous structure for the PVC-MWCNTs-PANI film with high surface area. The flexible porous PVC-MWCNTs-PANI film showed much higher specific capacitance value of 837 mF cm−2 with 89% retention after 2000 cycles at a current density of 2.4 mA cm−2 compared to the flexible non-porous PVC-MWCNTs-PANI film prepared without the foaming process (153 mF cm−2 with 90% retention). Furthermore, the porous PVC-MWCNTs-PANI film could possess energy density of 74.4 μWh cm−2(31 Wh kg−1) and power density of 0.96 mW cm−2(400 W kg−1). A flexible symmetric supercapacitor device made from two flexible porous PVC-MWCNTs-PANI films with the solid-state PVA/H2SO4 electrolyte exhibited high electrochemical performance. The enhanced supercapacitive performance of the obtained flexible device is due to the synergistic effect of PANI with MWCNTs, the porous 3D network structure and high wettability of the flexible films.

Modified conductive polyaniline-carbon nanotube composite electrodes for bioelectricity generation and waste remediation

Anode with good electrocatalytic capabilities is more specifically required to reduce the ohimic losses during microbial fuel cell (MFC) operation. Highly conductive polymers viz., Polyaniline (PANi) and Polyaniline/Carbon nanotube (PANi/CNT) composite were prepared by in situ oxidative chemical polymerization method. Anodes were fabricated independently by coating PANi and CNT/PANi composites on the surface of SSM. The fabricated electrodes were evaluated as anode against stainless steel mess (SSM) as cathode during MFC operation. Maximum bioelectricity generation was observed in SSM-PANi/CNT-anode with power density of 48 mW/m2 and COD removal efficiency of 80% compared with SSM-PANi-anode (38 mW/m2; 65%) and SSM-anode (28 mW/m2; 58%). Bioelectrochemical characterization of the electrode materials using cyclic voltammetry and electrochemical impedance spectroscopy showed high electrocatalytic activity of PANi/CNT composite electrode. The study concluded the efficiency of PANi/CNT composite electrodes as bioanode in operation of MFCs towards achieving increased bioelectricity production along with wastewater treatment.

Polyaniline/carbon nanotube core–shell hybrid and redox active electrolyte for high-performance flexible supercapacitor

Integrated polyaniline/carbon nanotubes (PANI/CNTs) hybrid with shell/core nanostructure is fabricated by chemical vapor deposition and electrochemical deposition for flexible supercapacitor (SC) application. CNTs with homogeneous worm-like morphology and high conductivity are used as a skeleton to support high electrochemical active PANI. The PANI/CNTs core–shell hybrid displays high specific capacitance of 823 F g− 1 in 1 M H2SO4 electrolyte at 5.0 A g− 1, the enhanced specific capacitance of 1128 F g− 1 was obtained with 0.02 M Fe3+/Fe2+ as redox additive in the electrolyte. Additionally, flexible symmetric SC has been assembled using PVA/H2SO4/Fe3+/Fe2+ as redox active gel electrolyte. The flexible SC exhibits an improved energy density as high as 22.9 Wh kg− 1 at a power density of 700.1 W kg− 1 and affords the capacitance retention of 97% after 2000 charge–discharge cycles. Furthermore, the fabricated SC device shows good flexibility and the output potential or current can be improved by connected three SC into series or parallel type. These results provide the potential and effective approach to enhance the electrochemical performances of flexible SC.

An LC Passive Wireless Gas Sensor Based on PANI/CNT Composite.

This paper proposes a wireless passive gas sensor based on the principle of LC mutual coupling. After the acidification of the carbon nanotube (CNT), the in-situ polymerization of the aminobenzene monomers was conducted on the surface of the acidified CNT to form a sensitive material composed of a polyaniline/carbon nanotube (PANI/CNT) composite. The Advanced Design System (ADS) software was used for simulating and analyzing the designed structure, which obtained the various parameters of the structure. A lead-free aluminum paste was printed on an alumina ceramic substrate via the screen printing technique to form an inductor coil, before the gas sensitive material was applied to prepare a wireless passive gas sensor, consisting of a single-turn inductor and interdigitated electrodes on the base structure. Finally, an experimental platform was built to test the performance of the sensor. The sensitivity of the gas sensor is about 0.04 MHz/ppm in an atmosphere with a NH3 concentration of 300 ppm. The sensor was shown to have good repeatability and high stability over a long time period.

A facile approach to improve the electrochemical properties of polyaniline-carbon nanotube composite electrodes for highly flexible solid-state supercapacitors

We seek to improve the electrochemical properties of supercapacitor via engineering the interface of electroactive material/current collector. A facile electrochemical method is put forward to fabricate expanded graphite (ExGP), and polyaniline-carbon nanotube (PANI-CNT) composite electrodes using ExGP as substrate are prepared by one-step co-electrodeposition. Compared with PANI-CNT/GP electrodes, PANI-CNT/ExGP electrodes show significantly improved electrochemical capacitive performances due to reduced constriction/spreading resistance. This effect is ascribed to the increased area of contact points at the interface of electroactive material/current collector for the latter. The PANI-CNT/ExGP electrodes deliver a specific capacitance of 826.7 F g−1, higher than previous reports based on PANI-CNT composites. A highly flexible solid-state supercapacitor is assembled using PANI-CNT/ExGP electrodes. The device shows high rate capability, superior energy/power characteristics (7.1 kW kg−1 at an energy density of 12.0 Wh kg−1), and good cycling stability. This study demonstrates that optimizing electroactive material/current collector interface can implement faster electron transport and represents an effective strategy to promote electrochemical capacitive properties of supercapacitors.