Carbon Nanotube Nanocomposites Research Articles

Metallization of 3D-Printed UV Photopolymer Structures by the Incorporation of Pd-Decorated Carbon Nanotubes

Pd-decorated carbon nanotube (CNT) nanocomposites were added to a UV photopolymer resin to be used as the ink in the printing of three-dimensional (3D) structures. The nanocomposites were prepared with a UV-induced reduction method, in which Pd nanoparticles with a size ranging from 10 to 150 nm were produced and decorated on CNTs. The printed 3D structures from the resin containing 1.0 wt % Pd-decorated CNTs exhibited much improved mechanical properties, achieving a 40% enhancement in fracture strength and a 40% increase in microhardness over the 3D structures printed from the bare resin. In the presence of Pd-decorated CNTs as catalyst seeds, further deposition of defect-free, nearly conformal Ni–P layer on the 3D-printed structures at a high deposition rate can be realized. The cross-cut adhesion testing revealed a significantly enhanced adhesion between the deposited Ni–P layer and the 3D-printed structures. The metallized 3D-printed structures displayed superior electrical conductivity, showing an electrical resistance down to 0.11 Ω as 1.0 wt % Pd-decorated CNTs were incorporated. The findings from this work highlight the merits of employing Pd-decorated CNTs as both mechanical property enhancer and catalyst seeds in the advanced manufacturing of 3D-printed structures.

Structural conductive carbon nanotube nanocomposites for stretchable electronics

Carbon nanotube (CNT) nanocomposites have been widely used for electronic devices because of their high conductivity and ease of processing. However, these nanocomposites have limited functionality because of their rigid intrinsic mechanical properties. In this study, we fabricated a stretchable serpentine structure using a CNT nanocomposite with a carboxymethyl cellulose binder. For a flexible mold, a polydimethylsiloxane (PDMS) was cast by the stretchable serpentine structure fabricated by a 3D printer. The CNT nanocomposite slurry was squeegeed into the serpentine-patterned PDMS mold. Fourier-transform infra-red spectroscopy and scanning electron microscopy were used to analyze the material properties of the nanocomposites with 15–45 wt% CNTs. We analyzed the serpentine grid structure using current-voltage curves, strain resistance values, and the Joule heating effect. Next, we developed the structural CNT nanocomposite electrode (SCNE) that was insulated by PDMS, and induced a skin-warming effect by Joule heating. Furthermore, light emitting diodes (LEDs) were implanted in series into a T-shaped linear SCNE, which had greater stretchability. The nine LEDs embedded in the SCNE were successfully operated by applying 20 V during the bending of the structure. Finally, the serpentine-shaped linear SCNEs with serially-implanted LEDs were programmed to light the LEDs in unison with the beat of a song.

Electrical and Structural Properties of HDPE/MWCNT/PE-g-MAH Nanocomposites Prepared Using Solution Mixing and Hot Compaction Two-step Approach

Background:MWCNTs tend to form agglomerates in nonpolar polymers due to their small size and large surface area. A promising approach to facilitate their dispersion within the polymeric matrix is based on employing a compatibilizer agent.Objective:The current study aimed to investigate the effect of a compatibilizer agent based on maleic anhydride grafted HDPE (PE-g-MAH) on the electrical and morphological properties of highdensity polyethylene/multi-wall carbon nanotubes nanocomposites (HDPE/MWCNT/PE-g-MAH) prepared by solution mixing and hot compaction two-step approach.Methods:A two-step approach based on solvent mixing and hot compaction was used to prepare nanocomposites of HDPE/MWCNT/PE-g-MAH with different MWCNTs and PE-g-MAH contents. The electrical, morphological, and HDPE crystalline structure properties of the nanocomposites were characterized by impedance spectroscopy, high-resolution field emission scanning electron microscopy, and X-ray diffraction, respectively.Results:The results confirm the positive role of the PE-g-MAH compatibilizer in enhancing the dispersion of the MWCNTs and, in turn, the formation of more conductive pathways at low MWCNTs content in the nanocomposites. Adding 2 wt% of the compatibilizer to the nanocomposite of 1 wt% MWCNTs increases the electrical conductivity by more than three orders of magnitude. Increasing the MWCNTs concentration by more than 1 wt% leads to a limited enhancement in conductivity of the nanocomposite prepared using 2 wt% of PE-g-MAH compatibilizer. Meanwhile, the morphological characterization revealed that the limited increase in conductivity of nanocomposites with only 1 wt% compatibilizer is related to a substantial increase in the HDPE crystallinity (from 14.8 to 43.9%) induced by the enhanced nucleating effect of the dispersed MWCNTs. The excess HDPE crystalline regions suppress the formation of effective MWCNTs conducting pathways due to their confinement into smaller inter-crystallite regions in the nanocomposite.Conclusion:Therefore, a balanced role of the compatibilizer between the dispersion of the MWCNTs and the nucleation of more HDPE crystallites has to be achieved by carefully selecting the compatibilizer type and concentration.

Superior electro-optical switching properties in polymer dispersed liquid crystals prepared with functionalized carbon nanotube nanocomposites of LC for switchable window applications

In this work, we are reporting the results on electro-optical switching properties of polymer dispersed liquid crystal (PDLC) devices for switchable window related applications. The PDLC cells are prepared by mixing octadecylamine functionalized single-walled carbon nanotubes (ODA-SWCNT) nanocomposites of liquid crystals (LC) and acrylate-based monomer by polymerization induced phase separation method. The important switchable device parameters such as threshold voltage, switching voltage, response time, contrast ratio and effective refractive index are investigated. The PDLC cells prepared with 0.05 wt% ODA-SWCNT nanocomposites of the LC, 7CB show almost zero threshold field and 36% less driving field compared to PDLC prepared with pure 7CB. A distinct optical response (frequency doubling) phenomenon is observed for PDLC prepared with 0.03 and 0.05 wt% ODA-SWCNT nanocomposites of 7CB compared to PDLC cells prepared with pure 7CB and lower concentrations (<0.03 wt%) of ODA-SWCNT. The relaxation of optical transmittance is observed at low frequency even when the applied electric field (Eapp) is ON which is due to the strong induced internal electric field (due to free ions) which nullifies the Eapp. The physical mechanism of this unique optical behavior is discussed in detail. The PDLC prepared with 0.01 wt% ODA-SWCNT show 84% faster response time compared to PDLC prepared with pure 7CB. The working of prototype PDLC devices for use in switchable window related applications is reported. The results indicate that, the PDLC prepared with 0.05 wt% ODA-SWCNT nanocomposites of 7CB show high ON state clarity and high OFF state opacity compared to PDLC prepared with pure LC and lower concentrations of ODA-SWCNT.

Modeling the thermal conductivity of carbon nanotube (CNT) nanofluids and nanocomposites – a fresh restart

After two decades of discussion it seems that the model-based prediction of the thermal conductivity of carbon nanotube (CNT) nanofluids and nanocomposites has come to a dead end and needs a fresh restart, since misleading statements and claims and repeated over and over again, mainly in the current literature on CNT nanofluids. In this paper a simple but rigorous model is presented (in two variants) for predicting the thermal conductivity of CNT nanofluids and nanocomposites. The model is based on Fricke's classical Maxwell-type effective medium approximation for systems with spheroidal particles, but – in contrast to all previous models – takes into account the Molyneux bounds for describing the random orientation of the CNTs. We show that the predictions of our model are significantly lower than the corresponding predictions via Nan's model and will thus turn out to be closer to experimental data reported in the literature.

Effect of MWCNTs Incorporation Into Polypyrrole (PPy) on Ammonia Sensing at Room Temperature

We reported the gas sensing properties of nanocomposites of polypyrrole (PPy) and multiwalled carbon nanotubes (MWCNTs) made with two incorporation techniques, i.e., ex situ and in situ polymerization. The pure PPy and PPy-MWCNT nanocomposites prepared by both techniques were characterized by field emission scanning electron microscopy (FESEM), Raman, and Fourier transform infrared spectroscopy (FTIR). The good dispersion was confirmed for the MWCNTs into PPy matrix prepared via in situ technique. Furthermore, the gas sensing measurements of pure PPy and ex situ synthesized PPy-MWCNT nanocomposite were carried out for the case of NH3 at room temperature, and they revealed a slight increase in response for PPy-MWCNT (1.5 wt%) sample. Then, different mass ratios of MWCNTs (0.5–3.5 mg) were incorporated into PPy matrix via in situ polymerization, and sensing toward NH3, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{H}_{{2}}$ </tex-math></inline-formula> , <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{C}_{{2}}\text{H}_{{5}}$ </tex-math></inline-formula> OH, and CO2 was investigated. The in situ prepared PPy-MWCNT (2.5 mg) composite showed superior sensing with 1.33%–29.74% response for 5–200 ppm NH3, 47/111 s as response/recovery time, high selectivity, and good repeatability toward NH3.

MWCNTs/PVA Hydrogel-Modified Electrochemical Sensors for Ex Vivo and In Vivo Detection of Pyocyanin Biomarker for Pseudomonas aeruginosa Wound Infection

Pseudomonas aeruginosa is the most prevalent cause of diabetic wound infection and amputation. Pyocyanin is one of the popular markers to identify Pseudomonas infections. However, no existing sensors are on the verge of being used as a suitable sensor for detecting pyocyanin in real-world applications. This study employed a physically cross-linked approach to decorate the surface of a working electrode with a multiwalled carbon nanotube (MWCNTs/PVA) nanocomposite, which increases electron transport, sample absorption, and biocompatibility. Under optimal conditions, the electrochemical behavior of a pyocyanin sensor was investigated using cyclic voltammetry and square wave voltammetry. The developed pyocyanin sensor demonstrated an excellent analytical range covering a clinically relevant range of 1–100 μM pyocyanin in various sample matrices including phosphate buffer, Lysogeny broth, simulated wound exudate, and Mueller–Hinton broth, showing a detection limit of 0.48, 0.10, 1.63, and 0.39 μM, respectively, with R2 > 0.99. The sensor’s potential wearability and point-of-care capability were demonstrated by detecting pyocyanin in wounds on ex vivo porcine skin and an in vivo animal model with excellent biocompatible property, achieving cell viability of L-929 > 80%. The detection could be performed directly in various sample matrices without any preparation processes. The sensor demonstrated high selectivity and sensitivity in the presence of common wound interferences. As a result, the proposed method has the potential to be a promising sensor for the early detection of P. aeruginosa infection in wounds in the perspective of wound care technology in the future.

Metal-carbon nanotube composite for wavelength-selective bolometer with improved characteristics

This work comprehensively discusses the utilization of a metal-multiwalled carbon nanotube (CNT) nanocomposite of gold (Au)/CNT for uncooled bolometric application synthesized by a simple rapid green synthesis technique. Enhanced light–matter interaction with the visible (532 nm) and near-infrared (1064 nm) radiations in the nanocomposite is utilized for achieving improved bolometric response at room temperature (RT, ∼300 K). A comparatively higher temperature coefficient of resistance of ∼−0.11%/K (improvement of ∼57%) was achieved in the Au/CNT nanocomposite bolometer (BM). Additionally, the composite BM demonstrated a dual (532 and 1064 nm) spectral selectively and enhanced sensitivity with respective large RT voltage responsivities of ∼11.70 ± 3.45 V/W and ∼503.54 ± 12.77 mV/W, as opposed to null response from the CNT BM. The current study, thus, demonstrates an important step toward designing high-performing CNT BMs for uncooled operation, with added functionality of wavelength-selectiveness.

Achieving Both Ultrahigh Electrical Conductivity and Mechanical Modulus of Carbon Films: Templating-Coalescing Behavior of Single-Walled Carbon Nanotube in Polyacrylonitrile.

Promoting the feasibility of carbon films as electrode applications requires sufficient performances in view of both electrical and mechanical properties. Herein, carbon films with ultrahigh electrical conductivity and mechanical modulus are prepared by high temperature carbonization of polyacrylonitrile (PAN)/single-walled carbon nanotube (SWNT) nanocomposites. Achieving both performances is ascribed to remarkable graphitic crystallinity, resulting from the sequential templating-coalescing behavior of concentrated SWNT bundles (B-CNTs). While well-dispersed SWNTs (WD-CNTs) facilitate radial templating according to their tubular geometry, flattened B-CNTs sandwiched between carbonized PAN matrices induce vertical templating, where the former and latter produce concentric and planar crystallizations of the graphitic structure, respectively. After carbonization at 2500 °C with the remaining WD-CNTs as microstructural defects, the flattened B-CNTs coalesce into graphitic crystals by zipping the surrounding matrix, resulting in high crystallinity with the crystal thicknesses of 27.4 and 39.4nm for the (002) and (10) planes, respectively. For comparison, the graphene oxide (GO) containing carbon films produce a less-ordered graphitic phase owing to irregular templating, despite the geometrical consistency. Consequently, PAN/B-CNT carbon films exhibit exceptional electrical conductivity (40.7× 104 S m-1 ) and mechanical modulus (38.2 ± 6.4GPa). Thus, controlling the templating-coalescing behavior of SWNTs is the key for improving final performances of carbon films.

Ultrasensitive Room-Temperature NO2 Detection Using SnS2/MWCNT Composites and Accelerated Recovery Kinetics by UV Activation

High performance with lower power consumption is one among the essential features of a sensing device. Minute traces of hazardous gases such as NO2 are difficult to detect. Tin disulfide (SnS2) nanosheets have emerged as a promising NO2 sensor. However, their poor room-temperature conductivity gives rise to inferior sensitivity and sluggish recovery rates, thereby hindering their applications. To mitigate this problem, we present a low-cost ultrasensitive NO2 gas sensor with tin disulfide/multiwalled carbon nanotube (SnS2/MWCNT) nanocomposites, prepared using a single-step hydrothermal method, as sensing elements. Relative to pure SnS2, the conductivity of nanocomposites improved significantly. The sensor displayed a decrease in resistance when exposed to NO2, an oxidizing gas, and exhibited p-type conduction, also confirmed in separate Mott-Schottky measurements. At a temperature of 20 °C, the sensor device has a relative response of about ≈5% (3%) for 25 ppb (1 ppb) of NO2 with complete recovery in air (10 min) and excellent recovery rates with UV activation (0.3 min). A theoretical lower limit of detection (LOD) of 7 ppt implies greater sensitivity than all previously reported SnS2-based gas sensors, to the best of our knowledge. The improved sensing characteristics were attributed to the formation of nano p-n heterojunctions, which enhances the charge transport and gives rise to faster response. The composite sensor also demonstrated good NO2 selectivity against a variety of oxidizing and reducing gases, as well as excellent stability and long-term durability. This work will provide a fresh perspective on SnS2-based composite materials for practical gas sensors.

Investigation of the structure and tensile strength of ultrahigh molecular weight polyethylene and amide functionalized single-walled carbon nanotubes nanocomposites

Investigation of the structure and tensile strength of ultrahigh molecular weight polyethylene and amide functionalized single-walled carbon nanotubes nanocomposites

Separating Curing and Temperature Effects on the Temperature Coefficient of Resistance for a Single-Walled Carbon Nanotube Nanocomposite

The temperature coefficient of resistance (TCR) determines the electrical performance of materials in electronics. For a carbon nanotube (CNT) nanocomposite, change of resistivity with temperature depends on changes in CNT intrinsic conductivity, tunnelling thresholds and distances, matrix' coefficient of thermal expansion, and other factors. In our study, we add one more influencing factor-the degree of cure. Complexities of the curing process cause difficulties to predict, or even measure, the curing state of the polymer matrix while uncertainty in the degree of cure influences TCR measurements leading to biased values. Here we study the influence of the cure state on the TCR of a single-walled CNT/epoxy polymer nanocomposite. For the given degree of cure, TCR measurements are conducted in the temperature range 25-100 °C, followed by the next 24 h of post-curing and a new cycle of measurements, 8 cycles in total. We find that contrary to industry practice to expect a high degree of cure after 3 h at 130 °C, the curing process is far from reaching the steady state of the material and continues at least for the next 72 h at 120 °C, as we observe by changes in the material electrical resistivity. If TCR measurements are conducted in this period, we find them significantly influenced by the post-curing process continuing in parallel, leading in particular to non-monotonic temperature dependence and the appearance of negative values. The unbiased TCR values we observe only when the material reaches the steady state are no longer influenced by the heat input. The dependence becomes steady, monotonically increasing from near zero value at room temperature to 0.001 1/°C at 100 °C.

Electromagnetic wave absorption in graphene nanoribbon nanocomposite foam by multiscale electron dissipation of atomic defects, interfacial polarization and impedance match

For carbon-based nanocomposites, enhanced conduction loss, polarization loss and impedance match are beneficial for enhancing electromagnetic wave (EMW) absorption property. In this work, graphene nanoribbon (GNR) nanocomposite foam system with regulated atomic defects, enhanced interfacial polarization and suitable impedance match were combined to achieve high-efficient EMW absorption: (1) Tubular carbon nanotube (CNT) is unzipped via chemical oxidation to obtain GNR with unique structure of long strip; (2) Oxidation and reduction of GNR enables the regulation of in-plane atomic defects; (3) a suitable electrical conduction of GNR renders its nanocomposite a better impedance match than CNT or graphene nanoplatelet (GNP) nanocomposites; (4) cellular structure in GNR nanocomposite further improves the impedance match compared with air; (5) the long-strip characteristic of GNR features the high-efficient interfacial polarization even in cell walls which undergo stretching, while tubular CNTs have weak interfacial polarization and platelet GNPs have deteriorated interfacial polarization after cell wall stretching. Owing to the above specific tailored multiscale electron dissipation strategy, GNR nanocomposite presents better EMW absorption property of −42.6 dB than CNT nanocomposite of −21.8 dB and GNP nanocomposite of −25.6 dB. Furthermore, supercritical carbon dioxide (scCO2) foaming improves the impedance match and enhances GNR interfacial polarization. The EMW absorption property of GNR nanocomposite foam further increased to −54.1 dB after selectively and restrictively locating GNR in cell walls.

Bisphenol-A-Carbon Nanotube Nanocomposite: Interfacial DFT Prediction and Experimental Strength Testing.

Epoxies, their derivatives, and composites, due to superior specific strength, are preferred for many potential applications in the field of automobiles, aircraft, bonding of structures, protective coatings, water filtration, etc. As structural members in automobiles and aircraft, the epoxy-based components are exposed to various static/dynamic mechanical loading conditions during their service life. The interfacial interactions, between the matrix and reinforcement, greatly affect the final properties of the composites. The present study demonstrates that the solvent used for the preparation of the composite can also contribute toward interfacial interactions. Present research systematically finds out a suitable solvent (acetone) and reinforcement type [multi-walled carbon nanotube (CNT)] for epoxy [bisphenol-A (BPA)] nanocomposites. Dynamic and static strengths of the as-prepared epoxy-CNT nanocomposites were carefully investigated. Well dispersed CNTs in acetone were mixed with an ester of BPA under constant magnetic stirring conditions. Samples of tablet shape were prepared for testing static and dynamic performance of the composite using a nano-indentation technique. Considerable enhancement by 55 and 22% in the static elastic modulus and hardness of BPA-CNT composites, respectively, was observed (compared with that of pristine BPA). The storage modulus and tan-delta of the nanocomposites were also improved by 14 and 46%, respectively. Improved static and dynamic performance, reported in this work, significantly enhances the scope of utilization of BPA-CNT-based nanocomposites under severe static and dynamic loading conditions simultaneously. Static and dynamical analysis of CNT-reinforced epoxy provides more realistic understanding of the mechanical performance of the nanocomposite. Density functional theory (using QuantumATK software) simulations were performed to investigate and identify the alterations in the atomic morphology of CNTs during interfacial interaction with the acetone molecule and epoxy matrix. The calculations predicted that CNTs with mild defects as compared to pristine CNTs were better suited for synthesis of the nanocomposite and also assisted in a homogeneous distribution of CNTs in BPA without aggregation (with acetone as the solvent). Furthermore, structural changes in CNTs after treatment with BPA and the curing agent and the role of defects are studied in detail.

Effects of Annealing Temperature and Time on Properties of Thermoplastic Polyurethane Based on Different Soft Segments/Multi-Walled Carbon Nanotube Nanocomposites

Typically, polymer chains can move under the annealing process, resulting in an ordered structure arrangement. This causes an improvement in nanocomposite properties and in the dispersion of filler. In this research, annealed thermoplastic polyurethane (PU)/multi-walled carbon nanotube (MWCNT) nanocomposites were studied to investigate the effect of annealing on the selective dispersion of MWCNTs. PU matrices were composed of two different soft segments, i.e., polyether (PU-Ether) and polyester (PU-Ester). Nanocomposites were prepared by the melt mixing process and annealed at 80 to 120 °C for 6 to 24 h. The increases in annealing time and temperature resulted in microphase separation in segmented PU and the orientation of crystalline structures in the segregated hard domain. Nanocomposites showed higher electrical conductivity after annealing. This implies that the movement of PU chains during heat treatment encouraged the development of the MWCNT network. However, the increase in ordered structures could obstruct the MWCNT network, resulting in lower electrical conductivity levels. Considering the selective dispersion of MWCNT in PU matrices, it was found that MWCNTs dispersed in soft segments of PU-Ether, leading to a significant decrease in elongation at the break after annealing. On the other hand, a decrease in elasticity of PU-Ester nanocomposites was not observed as a result of MWCNT dispersal in hard segments.

AZO Nanoparticles-Decorated CNTs for UV Light Sensing: A Structural, Chemical, and Electro-Optical Investigation

Nanocomposites formed by aluminum-doped zinc oxide nanoparticles (AZO-NP) and multiwall carbon nanotubes (CNT) are proposed here as a promising material for UV light sensing applications, with the great advantage of operating in air, at room temperature, and at low voltage. Nanocomposite layers were prepared with different AZO:CNT weight ratios by a simple methodology at room temperature. They were characterized by means of UV-Vis spectroscopy, scanning and transmission electron microscopies (SEM and TEM), and X-ray photoelectron spectroscopy (XPS). The interaction between the two nanomaterials was demonstrated by comparing the properties of the nanocomposite with the ones shown by the AZO-NPs. Dense AZO-CNT nanocomposite layers were deposited between two metal electrodes on a SiO2/Si substrate, and the electrical properties were investigated in dark condition and under UV light irradiation. The electrical response to the UV light was a sudden current increase that reduced when the light was switched off. Several UV on/off cycles were performed, showing good repeatability and stability of the response. The mechanisms involved in the electrical response are discussed and compared to the ones previously reported for ZnO-CNT nanocomposites.

A self-cascade system based on Ag nanoparticle/single-walled carbon nanotube nanocomposites as an enzyme mimic for ultrasensitive detection of L-cysteine.

L-Cysteine, widely used in medicine and the food industry, is of great essentiality to organisms and the food quality. Given that current detection approaches require exacting lab conditions and tedious sample treatment, there is a pressing demand for developing a method that possesses advantages of user friendliness, prominent performance, and cost-effectiveness. Herein, a self-cascade system was developed for the fluorescence detection of L-cysteine based on the ingenious performance of Ag nanoparticle/single-walled carbon nanotube nanocomposites (AgNP/SWCNTs) and DNA-templated Ag nanoclusters (DNA-AgNCs). The fluorescence of DNA-AgNCs could be quenched on account of the adsorption of DNA-AgNCs on AgNP/SWCNTs by π-π stacking. With the cooperation of Fe2+, AgNP/SWCNTs with oxidase and peroxidase-like activities could catalyze the oxidation of L-cysteine to produce cystine and hydrogen peroxide (H2O2) and then break the O-O bond of H2O2 to generate a hydroxyl radical (·OH), which could cleave the DNA strand into different sequence fragments which subsequently peeled off from the AgNP/SWCNTs, resulting in a "turn-on" fluorescence response. In this paper, AgNP/SWCNTs with multi-enzyme activities was synthesized enabling the reaction to proceed in just one step. The successful preliminary applications for the L-cysteine detection in pharmaceutical, juice beverage, and serum samples indicated that the developed method exhibited great potential in medical diagnosis, food monitoring, and the biochemical field, which also broadened the horizon for follow-up research.

Impedance Sensor for Real-Time Ammonium Detection Based on MWCNT/ZnO Nanocomposites.

This work reports on the development of an impedance sensor-based real-time-field specific system to monitor aqueous Ammonium (NH4+). The sensing element was fabricated by modifying screen-printed interdigitated electrodes (IDEs) with a hybrid nanocomposite of Multi-Wall Carbon Nanotube (MWCNT) with Zinc Oxide (ZnO) nanocrystals. The NH4+ of the water was monitored, and it exhibited a sensitivity of 67.13 Ω /mM with average correlation coefficients of 0.80. The impedance magnitude ( Ω ) of the NH4+ sensor was unaffected by the presence of Fe2+, Ni2+, K+ and P+ interfering cations. The developed sensor was interfaced with an IoT-enabled NodeMCU microcontroller, enabling a direct method for continuous monitoring of NH4+ concentrations. This integrated system is interconnected to the field-deployed sensor nodes, which provide real-time NH4+ levels to the remote user through web applications.

Investigation of Carbon Nanotube Metal Zinc Oxide Nanoparticle Synthesis and its Applications

Background: Carbon nanotubes (CNT) synthesized by CVD method at 950 ℃. CNT and metal ZnO nanocomposites material synthesized by ball mill procedure have been examined. Stability of nanocomposite material has been attained by cationic ion liquid (IL), 1-tetradecyl-3 methylimidazolium chloride, structural morphology material characterized by Fourier transform infrared (FTIR) spectroscopy, Field emission scanning electron microscopy (FESEM), Ultraviolet visible (UV-Vis) spectroscopy. Furthermore, these materials were analyzed by Energy dispersive X-ray spectroscopy (EDX) to study for the percentage of elemental compositions. Current-Voltage (I-V) characterized by electrical properties are showing highly responsive of resistance variation and easy recoverable high sensitivity was the main feature of the CO2 gas sensing properties. Objective: Carbon nanotube and zinc oxide nanoparticle combined with different ratio and optimization of coating methods using for sensor applications. Methods: It is synthesized with chemical vapour deposition method and zinc nanoparticle developed by ball mill method. We have optimized spin coating and dip coating method on glass surface. Results: FTIR spectrum results are recommended that the existing hydroxyl group and C group CNT-ZnO nanoparticle covered by the surface active site of ZnO. The size and composition of the CNT-ZnO were confirmed by FESEM EDAX studies. The absorption and transmittance wavelength of CNT-ZnO nanoparticle were recorded by UV-Visible spectroscopy. The I-V property shows that the drain current and voltages are varied by gas implying the materials suitable for applications. Conclusion: This module can be used to monitor CO¬2 gas application instruments with help of software. In future, this module and techniques can be used to study stress sensor and piezoelectric applications

Facile synthesis of cobalt fluoride (CoF2)/multi-walled carbon nanotube (MWCNT) nanocomposites and improvement of their electrochemical performance as cathode materials for Li-ion batteries

Conversion-type metal fluoride cathodes are considered promising candidates for electrochemical applications owing to their large specific capacities and high operating voltages.