Single Multi-walled Carbon Nanotube Research Articles

Tuning the Charge Transfer in MWCNTs via the Incorporation of ZnONPs and AgNPs: The Role of Carbon Binding with ZnO/Ag Heterostructures in Reactive Species Formation.

In this research, multi-walled carbon nanotubes (MWCNTs) were decorated with two kinds of nanostructures, (1) silver nanoparticles (AgNPs) and (2) zinc oxide-silver nano-heterostructures (ZnO/Ag-NHs), via an accessible chemical coprecipitation method assisted with ultrasonic radiation. The high-resolution transmission electron microscopy analysis demonstrated the successful decoration of MWCNTs with the nanostructures with a diameter size of 11 nm ± 2 nm and 46 nm ± 5 nm for the AgNPs and the ZnO/Ag-NHs, respectively. The reactive species were promoted in an aqueous medium assisted with UV irradiation on the functionalized MWCNT. UV-Vis spectroscopy demonstrated that production of the reactive species density increased 4.07 times, promoted by the single MWCNT after the functionalization. X-ray photoelectron spectroscopy showed that Sp2 hybridization in carbon atoms of MWCNTs participates in the binding of AgNPs and ZnO/Ag-NH decoration and thus participates in the formation of reactive species in an aqueous medium, as is the case for cancer cells.

Combined toxicity of multiwall carbon nanotubes and cadmium on rice (Oryza sativa L.) growth in soil

The comprehensive effects of nanoparticles and coexisting heavy metals on plant growth are still unclear, especially in soil medium. The single and combined effects of multiwall carbon nanotubes (MWCNTs) and cadmium (Cd) on rice (Oryza sativa L.) growth were examined in this study through a 4 months pot experiment in 2022. Rice plants were exposed to different concentrations of MWCNTs (100 and 500 mg kg−1) in the presence of 5.0 mg kg−1 Cd stress. At the tillering stage, the 500 mg kg−1 MWCNTs addition reduced plant height by 8.0% and increased soluble protein content in the leaves by 13.7%, demonstrating that a single MWCNTs had a slight negative impact on rice growth. When exposed to Cd stress, the inclusion of 500 mg kg−1 MWCNTs led to a 6.7%–9.0% decrease in bioavailable Cd level in soil, resulting in considerable reductions in Cd content in roots (23.4%–29.9%), shoots (24.5%–28.3%) and grains (28.3%–66.2%). Compared to the single Cd treatment, the O. sativa L. leaves treated with Cd and MWCNTs (500 mg kg−1) had considerably reduced levels of malondialdehyde (MDA), soluble protein, and activities of antioxidant enzymes (POD, CAT, and SOD). The findings of this study indicated that appropriate concentrations of MWCNTs application in soil could alleviate Cd-induced toxicity on rice growth.

Irreversibility scrutiny of SWCNT and MWCNT nanofluid convective flow using Darcy-Forchheimer rule in an upright microchannel with variable thermal conductivity and Brownian motion and thermophoresis

Carbon nanotubes are used to attain greater thermal transfer rates in a various of enormous applications in the field of microsystem, emission, conductive polymers, fibers, and fabrics. Hence the aim of this article is to explore the entropy generation analysis of single wall carbon nanotubes and multiwall carbon nanotubes flow in an upright micro channel with variable thermal conductivity. The exponential heat source and non-linear thermal radiation were considered. The micro channel retains the no slip and convective boundary conditions. The Buongiorno model was used in this study, which emphasizes the light on Brownian motion and thermophoresis phenomena that occur during the fluid flow. Darcy- Forchheimer model is also taken into account. The governing equation numerically solved by employing Runge-Kutta Fehlberg's fourth-fifth order. The repercussion of this study upholds that the inflates of variable thermal conductivity magnify the thermal field. Entropy production inflates at right wall of the channel with augmented Brownian parameter and exhibits exactly opposite behavior at left wall of the channel. One of the important tasks of the investigation was to compare SWCNT and MWCNT. The findings confirmed that multiwall carbon nanotubes exhibit more magnificent heat and mass transfer than single wall carbon nanotubes.

Energy matrices, enviro-economic and characteristic equation-based performance analyses of photovoltaic thermal compound parabolic concentrator (PVT-CPC) coupled solar still equipped with heat exchanger using SWCNTs and MWCNTs–water nanofluids

In this paper, effect of single wall carbon nanotubes (SWCNTs) and multiwall carbon nanotubes (MWCNTs)- water based nanofluid have been studied to examine the performance, long-term feasibility andenviro-enviro-economic analysis of partially covered series connected N- photovoltaic thermal (PVT)-compound parabolic concentrator (CPC) collectors coupled double slope solar still (DSSS) equipped with helically coiled heat exchanger (HE). Analysis have been carried out by developing thermal modelling of the proposed system. Instantaneous gain and loss efficiencies; annual thermal energy/exergy, and productivity – is investigated for optimized parameters of the proposed system in detail. Gain efficiency of the proposed system is found to be approximately 25-30% higher using CNT-NPs as compared to the system without using NPs. Annual thermal energy and exergy of CNTs, particularly SWCNTs water-based nanofluid (thermal energy- 2491.55 kWh, thermal exergy-894.67 kWh) have been found to be greater in comparison to basefluid (thermal energy -2185.76 kWh, thermal exergy-772.18 kWh). Also, results give higher value of CO2 mitigation using CNT-NPs both on the basis of energy (SWCNT-5.082t, MWCNT-4.787t) and exergy (SWCNT-1.83t, MWCNT-1.76t) respectively. SWCNT-NPs shows better performance due to their better TPPs; also PVT-CPC collector integrated DSSS equipped with HE is more viable practically.

Structural effects observed in rods fabricated from magnesium powder and multi-walled carbon nanotubes using different parameters of forward-backward rotating die extrusion (KOBO)

In this study the effects induced by 0.5 vol% of multiwalled carbon nanotubes (MWCNTs) in magnesium based rods, obtained by cold and hot forward-backward rotating die extrusion method (KOBO) were presented. A composite billets were fabricated from powder, sonically mixed prior to hot pressing under vacuum, and then extruded. Prior the extrusion process the billets were either at room temperature or heated up to 150 °C. The macrostructure and microstructure of rods surface, cross and longitudinal sections were characterized by LM, SEM with EDS and XRD methods. Moreover, the tensile strength, hardness and open porosity were determined for Mg/MWCNTs composites and reference rods of pure magnesium processed by KOBO. Presented studies allow to recognize the phenomena occurring in extruded rods, as well the role of initial billets heating and extrusion rate. After hot KOBO in all rod volume the nanotubes formed an elongated skeleton with some submicro or nanosized MgO content. But when the cold KOBO and higher extrusion rate were applied, two types of microstructure were detected in the rod, and the rod consisted of Mg-MWCNTs/MgO core well connected with surrounding free of skeleton α-Mg layer doped with single MWCNTs and nanosized MgO. That phenomena was not earlier reported in literature. Moreover, the Rietveld XRD examinations revealed a spectacular refinement of metal matrix crystallites in dynamic recrystallization, and this effect occurred due to MWCNTs presence. The MWCNTs application caused the rods properties increase. However, greater mechanical properties and lower porosity were obtained by extrusion of the heated up to 150 °C billet.

Magnetic carbon nanotubes (CNTs)-water-based nanofluid in the presence of thermal radiation and heat generation/absorption

The aim of this study is to examine the Marangoni boundary film problem of water-based CNTs nano-liquids in Darcian porous media. Two types of CNTs, namely Single Wall Carbon Nanotubes (SWCNTs-water) and Multi-Wall Carbon Nanotubes (MWCNTs-water), are considered in the presence of Bénard-Carlo Marangoni convection. The impact of an inclined magnetic field is considered. The heat transport mechanism is analyzed under the impression of nonlinear thermal radiation, heat generation, and absorption. Through Marangoni convection scattering, the system of partial differential equations is established. By utilizing generalized transformation, the model system is converted to an ordinary differential problem and then solved by using the Homotopy Asymptotic Method. It is demonstrated that the volume fraction of nanoparticles raises the velocity at the surface, whereas magnetic and porosity parameters lower the velocity at the surface. Furthermore, the controlling parameters help in increasing the heat transfer rate.

Effect of thermal radiation on nonDarcy hydromagnetic convective heat and mass transfer flow of a water–SWCNT’s and MWCNT’s nanofluids in a cylindrical annulus with thermo-diffusion and chemical reaction

The examined through analysis of the movement of water-based single wall carbon nanotube (SWCNT) and multiwall carbon nanotube (MWCNT) nanofluids in a coordinate annulated zone under influence of non-uniform heat source/sink. By imposing the appropriate nondimensional variables, the governing partial differential equations are converted into a system of coupled nondimensional partial differential equations. By means of the usage of quadratic polynomials and the Galerkin finite element detail approach, the nonlinear equations have been executed. The expressions representing fluid velocity, temperature and concentration are discussed graphically. While skin friction, heat transfer and mass transfer are revealed in tabular structure. The proposed scheme is shown to have faster convergence than the existing scheme with excellent accuracy. Various parametric values have been analyzed and observed that higher temperatures and concentrations are produced with lower velocities with and bigger velocities with higher radiative heat flux or nanoparticle volume fraction.

Crosstalk Peak Overshoot Analysis of VLSI Interconnects

As technology extended from deep sub-micron technology to nanometer regimes, the conventional copper (Cu) wire will not be able to continue. Now a substitute approaches such as Carbon Nano Tube (CNT) interconnects have been suggested to ignore the problems associated with global interconnects. Hence in this work, crosstalk analysis of Complementary metal oxide semiconductor (CMOS) buffer-driven of different interconnects have been analyzed for peak overshoot and overshoot width of Cu and CNTs for 16nm technology. For analyzing peak overshoot, the interconnect lengths are varied from 100um to 500um in 16 technology node for Cu, single walled carbon nanotube (SWCNT) and multi-walled carbon nanotube (MWCNT). The values of the peak overshoot and overshoot width changes, as the interconnect length increases, the peak overshoot and width is going to be increases. As Compared to Cu, SWCNT and MWCNT, the peak overshoot and width for SWCNT is lesser than copper and MWCNT. The MWCNT interconnect is less than that of conventional Copper interconnects.

Passively Q-switched erbium doped fiber laser based on graphene and carbon nanotube saturable absorbers

A passively Q-switched erbium-doped fiber laser (EDFL) was experimented on by employing graphene, single walled carbon nanotubes (SWCNT) and multi-walled carbon nanotube (MWCNT) saturable absorbers (SA). The SA film was obtained by embedding the graphene, SWCNT and MWCNT into polyvinyl alcohol (PVA). The graphene SA was prepared by dipping a PVA thin film into the graphene solution while carbon nanotubes SAs were prepared using the casting method and placed in the ring cavity to produce a stable pulse laser. Graphene, SWCNT and MWCNT SAs were operating at wavelengths of 1558.92 nm, 1557.98 nm and 1558.51 nm, respectively, whereas the continuous wave was 1560.72 nm at the input pump power of 56 mW. The pulse energy, output power, repetition rate and pulse width were compared in graphene, SWCNT and MWCNT SAs. The shortest pulse width retrieved in graphene, SWCNT and MWCNT were 3.90 µs, 3.62 µs 4.43 µs and produced at the repetition rate of 115.00 kHz, 130.70 kHz, and 89.13 kHz, respectively. In comparison to graphene and SWCNT SAs, MWCNT SAs exhibit the best performance in terms of output power of 2.19 mW and high pulse energy of 24.57 nJ in passively Q-switched EDFL.

Enhancing bonding behavior between carbon fiber-reinforced polymer plates and concrete using carbon nanotube reinforced epoxy composites

Externally bonded carbon fiber reinforced polymer (CFRP) composites have been widely used as repairing or strengthening materials for deteriorated reinforced concrete (RC) structures. This study discusses whether carbon nanotube (CNT) can be used as an additive to enhance bonding strength between concrete and CFRP. In this study, two CNT types: single walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs), were mixed with two different types of epoxies. CNTs were added at 0.25%, 0.5%, and 1.00% by weight of epoxy to obtain the optimal performance. Single-shear test were conducted to investigate bonding behavior including bond strength, ultimate slip, effective bond length, bond stress-slip relationship, interfacial fracture energy, and crack formation between CFRP plate and concrete. The results showed that epoxy modified by 0.5% SWCNTs and 1.0% MWCNTs by weight of epoxy enhance the ultimate load and slip, bond strength, and interfacial fracture energy when compared to plain epoxy. However, high density epoxy modified with SWCNTs/MWCNTs showed diminished bonding properties.

Field emission energy distribution studies of single multi-walled carbon nanotube emitter with gas adsorptions

The field emission electron energy distribution (FEED) investigation on the individual carbon nanotube (CNT) is a powerful approach to study the intrinsic electronic properties, including the work function and field emission energy level, for CNT devices. We fabricated the single multi-walled carbon nanotube (MWNT) emitter by the solution evaporation dielectrophoretic process after the chemical vapor deposition (CVD) synthesis of the MWNT film. The FEED properties of the MWNT emitter in hydrogen and nitrogen environments were investigated. The FEED peaks shifted up gradually in both hydrogen and nitrogen ambiences, indicating the effective work function reduction effect with gas adsorptions. The amounts of spectrum displacements increased with raising gas partial pressures, with larger displacements of up to 0.65 eV for hydrogen between 10−7 Pa and 10−4 Pa. The double peak spectra imply that emission electrons could be from the hexagonal and the pentagonal carbons. Meanwhile, high carbon content was detected in the ultimate vacuum, attributed highly to the MWNT etching from the emission. This investigation suggests that the work function variation plays key role for the field emission instability and the pressure sensing effect of CNT emitters.

Qualitative evidence of the flexoelectric effect in a single multi-wall carbon nanotube by nanorobotic manipulation

The flexoelectric effect corresponds to the linear variation of the electric polarization of a material subjected to a strain gradient (i.e., during its mechanical bending). Unlike piezoelectricity, it also exists in non-centrosymmetric materials. Furthermore, due to the gradient term, its magnitude can increase as the size of the system decreases. Thanks to this effect, nanoscale systems could be used to harvest thermal vibration energy to power a microdevice. These could be multi-wall carbon nanotubes since they are known to bend easily in an elastic manner. However, it is very challenging to experimentally measure the flexoelectric behavior of a single multi-wall carbon nanotube due to its small size (less than 50 nm in diameter), to the low level of induced charges, and to the need to vary the imposed stress. To progress in this direction, a six-degree-of-freedom robot with a fiber tip is used inside a dual-beam microscope to pick up few single carbon nanotubes from a tangle and connect them to the fiber tip. After ion-soldering the two tips, each carbon nanotube is dynamically bent several times while monitoring the brightness of the bending area and its effective radius of curvature. This allowed us to demonstrate qualitatively the flexoelectric effect at the level of a single multi-wall carbon nanotube.

The combined toxicity and mechanism of multi-walled carbon nanotubes and nano zinc oxide toward the cabbage.

The natural environment is a complex system, and there is never only one kind of nanomaterial entering the environment. However, many studies only considered the plant toxicity of one kind of nanomaterial and do not consider the influence of two or more kinds of nanomaterials on plant toxicity. Multi-walled carbon nanotubes (MWCNTs) and zinc oxide nanoparticles (ZnO NPs) are two common and widely used nanomaterials in water environment, so these two kinds of nanomaterials were chosen to explore the effects of their combined toxicity on cabbage. This study investigated the toxicity of MWCNTs combined with ZnO NPs on cabbage by measuring the length of roots and stems, chlorophyll content, oxidative stress, antioxidant enzyme activity, metal element content, and root scanning electron microscopy. The toxicity of single MWCNTs toward cabbage was attributed to direct oxidative damage, while the toxicity of single ZnO NPs toward cabbage was due to the high level of zinc concentration. Moreover, ZnO NPs (10 mg/L) ameliorated MWCNTs toxicity toward cabbage by improving the activity of antioxidant enzymes. ZnO NPs (50 and 100 mg/L) because of the high content of zinc disrupted the balance of other metals in the plant and increased the toxicity of MWCNTs. In conclusion, the combined toxicity of different concentrations and types of nanomaterials should be considered for a more accurate assessment of environmental risks.

Heat transport investigation of magneto-hydrodynamics (SWCNT-MWCNT) hybrid nanofluid under the thermal radiation regime

The prime objective of the present study is to examine the comparison of heat transfer attributes of magnetohydrodynamic hybrid nanofluid flow in the presence of radiation. The phenomenon of generally new standard fluid “hybrid nanofluid”, has been explored to enhance the heat coefficient in the boundary layer flow. Single wall and Multiwall carbon nanotube particles (nanometer in size) have been utilized to constitute the required hybrid nanofluid. The nonlinear system of differential equations is handled through the bvp4c MATLAB algorithm. The Nusselt number increases significantly for lower values of pressure and decreases for higher pressure gradients while keeping the radiation value at zero. The Sherwood number first increases for lower buoyancy parameters and then decreases for higher values, for both hybrid nanofluid cases. The local skin friction decreases for minimum rotation then it increases for higher rotation in both directions, it shows similar behavior for both cases. These hybrid nanofluids can enhance the performance of heat exchangers, electronic cooling, heating in pipes, car radiators, nuclear plants, solar heating. The study suggests exploitation of these fluids can be helpful to reduce the production cost.

Evaluation of the combined toxicity of multi-walled carbon nanotubes and cadmium on earthworms in soil using multi-level biomarkers

The coexistence of multi-walled carbon nanotubes (MWCNTs) with cadmium (Cd) in soil may cause the combined biological effects, but few study reported about their joint toxic effects on earthworms. Therefore, this study investigated the effects of sub-lethal levels of MWCNTs (10, 50, 100 mg/kg) and Cd (2.0, 10 mg/kg) on earthworms Eisenia fetida for 14 days. The changes in multi-level biomarkers of growth inhibition rate, cytochrome P450 isoenzymes (CYP1A2, 2C9 and 3A4), and small molecular metabolites (metabolomics) were determined. The toxic interaction between MWCNTs and Cd was characterized by the combination of the biomarker integration index (BRI), joint effect index concentration addition index (CAI), and the effect concentration addition index (EAI). The results showed that the single MWCNTs exposure caused insignificant change in most biomarkers, while the combined exposure of MWCNTs (50–100 mg/kg) and 10 mg/kg Cd led to significant changes in ten most important metabolites identified by metabolomics and activities of CYP1A2, 2C9, and 3A4. Compared with the toxicity of Cd alone, the combined toxicity of the mixture was significantly reduced. According to the integration of BRI and CAI/EAI, a clearly antagonistic interaction at relatively low effects was observed between MWCNTs and Cd. The responses of multiple biomarkers suggest the toxic action mode of the mixture on earthworms was related to the oxidative injury, and the disruption of amino acid, purine, and pyrimidine metabolism, and the urea cycle.

Irreversibility analysis of the couple stress hybrid nanofluid flow under the effect of electromagnetic field

PurposeThis paper aims to consider the heat transportation together with irreversibility analysis for the flow of couple stress hybrid nanofluid past over a stretching surface. The innovative characteristics of this paper include electro-magnetohydrodynamic (EMHD) term, viscous dissipation, Joule heating and heat absorption\\omission. The hybrid nanofluid is prepared due to the suspension of the solid nanoparticles of the single wall and multi-wall carbon nanotubes (SWCNTs and MWCNTs) in the blood for the testing purpose of heat transfer and drug deliveries. The experimental value of the Prandtl number used for the blood is 21 from the available literature and very large as compared to the Prandtl number of the other base fluids. Appropriate transformations are incorporated to convert the modeled partial differential equations into the nonlinear ordinary differential equations. The homotopy analysis method (HAM) is used to obtain the solution. The explanation for velocity, energy and entropy are exposed under the influence of various parameters such as E, M, k, Q, S and Ec. The numerical values are calculated and summarized for dimensionless Cf and Nu.Design/methodology/approachIn this investigation, heat transportation together with irreversibility analysis for the flow of couple stress hybrid nanofluid past over a stretching surface is considered. The innovative characteristics of this paper include EMHD term, viscous dissipation, Joule heating and heat absorption\\omission. The hybrid nanofluid is prepared due to the suspension of the solid nanoparticles of the SWCNTs and MWCNTs in the blood for the testing purpose of heat transfer and drug deliveries. The experimental value of the Prandtl number used for the blood is 21 from the available literature and very large as compared to the Prandtl number of the other base fluids. Appropriate transformations are incorporated to convert the modeled partial differential equations into the nonlinear ordinary differential equations. The HAM is used to obtain the solution. The explanation for velocity, energy and entropy are exposed under the influence of various parameters such as E, M, k, Q, S and Ec. The numerical values are calculated and summarized for dimensionless Cf and Nu.FindingsThe explanation for velocity, energy and entropy are exposed and the flow against various influential factors is discussed graphically. The numerical values are calculated and summarized for dimensionless In addition, the current study is compared for various values of to that published literature and an impressive agreement in terms of finding is reported. It has also been noticed that the and factors retards the hybrid nanofluid flow, while the temperature of fluid becomes upsurges by the rise in these factors.Originality/valueThis is examined while evaluating the previously discussed publications that study on EMHD aspects of magnetized Casson type hybrid nanofluid via entropy generation research is innovative but also acknowledging that the couple stress model challenged bilaterally on stretching surface has not yet been studied. So, there is an ongoing attempt to bridge such a space.

Multi-Walled Carbon Nanotubes and Carbon Black Incorporated Heterogeneous Layered Polymer Composites with Enhanced Electrical Features

The present work is centered on the study of electrical properties of three different types of composites i.e. single layer carbon black (CB) and multi-walled carbon nanotubes (MWCNTs) based PMMA composites, CB/PMMA and MWCNTs/PMMA, and bilayer polymer composites CB/PMMA-MWCNTs/PMMA, prepared by solution mixing method using chloroform as dispersion medium. It is expected that two layers in bilayer polymer composites would show increased interfacial interactions resulting in improved electrical character especially dielectric properties. Prepared composites have been characterized by UV-Vis and FTIR spectroscopy for successful synthesis. Electrical properties, conductivity, dielectric constant and tangent loss of all composites were measured at frequency range of 40Hz to 1MHz by using LCR meter. Percolation threshold value was obtained by using data of electrical conductivity as a function of volume fraction of fillers. The obtained value of percolation threshold was much lower for bilayer polymer composites i.e. 0.01 vol% as compared to the single layer polymer composites. Observed data of dielectric constant encourages the synthesis of composites with this kind of structure.

Significance of increasing Lorentz force and buoyancy force on the dynamics of water conveying SWCNT and MWCNT nanoparticles through a vertical microchannel

Carbon nanotubes are used to achieve high heat transfer rates in a variety of engineering applications include thermal storage systems, electronic component cooling, high-performance building insulation, heat exchangers and drying technologies. Hence the aim of this article is to examine the addition of single walled carbon nanotubes (SWCNT) and multi-walled carbon nanotubes (MWCNT) to water in a vertical microchannel to improve heat transfer. The effects of MHD, slip, convective boundary condition and heat source/sink are incorporated. The Brinkman-Forchheimer flow model and type II hybrid nanofluid model is adopted. Converted dimensionless differential equations are solved numerically via Dsolve command with the aid of Maple. The simulation assessment is worked out by graphs. One of the main tasks of the analysis is to compare MWCNT/water and SWCNT-MWCNT/water. It is shown that the improvement of the heat source/sink parameter improves the temperature and the rate of heat transfer in MWCNT/water is higher than SWCNT-MWCNT/water. Also larger values of Lorentz force and buoyancy force decreases the drag coefficient.

Impact of MHD radiative flow of hybrid nanofluid over a rotating disk

PurposeIn this article, we scrutinized the impacts of non-linear thermal radiations on SWCNT−TiO2&MWCNT−CoFe2O4 nanoparticles suspended in water-based hybrid type nanofluid flow over rotating disk. The effects of nonlinear thermal radiation are considered. The flow is induced through rotating disk. There is a huge market for nanotechnology, and the development of these materials can be predicted to be very light. The effects of shape factors are also considered. Nanomaterials are characterized into different types due to its shapes, features and size of materials. General types nanomaterials catagories include carbon nanotubes. Further CNTs are divided into two different shapes includes single wall carbon nanotudes (SWCNTs) and multi-wall carbon nanotubes (MWCNTs). Carbon nanotubes have significants applications in energy storages, damping and fracture toughness stiffness. Carbon nanotubes are most commonly used in the fields of energy conservation, thermal stability, nanotubes transistors and electromagnetic fields and many areas. MethodologyThe system of governing partial differential equations are reduced to dimensionless ordinary equations by using similarity transformations and then solved with bvp4c in-built function Matlab. behavioral analysis of velocity components and heat transfer of different parameter values are evaluated utilizing graphs. FindingsThe results shows that Velocity components are reduces via larger estimation of magnetic parameter. The solid particle frictions improves the velocity field. temperature ratio parameter aid to improves the heat transfer. Furthermore temperature is reduced via Prandtl number.

A chemiresistive gas sensor for sensitive detection of SO2 employing Ni-MOF modified –OH-SWNTs and –OH-MWNTs

Sulfur dioxide (SO2) is prominent as hazardous gas owing to its unpropitious effects on the ecosystem. In this report, a flexible SO2 gas sensor is reported by solvothermally synthesized crystalline nickel(II)benzenetricarboxylate metal–organic framework (Ni-MOF) modified with hydroxyl group (–OH) activated single wall carbon nanotubes (SWNTs) and multi-walled carbon nanotubes (MWNTs), respectively. Introduction of –OH-SWNTs and –OH–MWNTs played crucial role in the improvement in electrical and morphological properties of Ni-MOF as well as boosted the sensing ability toward SO2 gas at room temperature. The structural and spectroscopy properties of pristine Ni-MOF, Ni-MOF/–OH–SWNTs and Ni-MOF/–OH-MWNTs were studied by X-Ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR), respectively. Atomic force microscopy (AFM) and field emission scanning electron microscope (FESEM) were used for the morphological analysis of synthesized material. The selective response of Ni-MOF/–OH-SWNTs and Ni-MOF/–OH-MWNTs toward SO2, NO2, NH3 and CO analytes (0.5–15 ppm) was withal studied by monitoring the changes in electrical resistance of the material at room temperature. The present study reveals that doping of –OH-SWNTs and –OH-MWNTs into the MOF leads to efficient increment in the sensing characteristics. The composite of Ni-MOF/–OH-SWNTs exhibited better sensing response (10 s) with less recovery time (30 s) for 1 ppm concentration along with considerable sensitivity (0.9784) and selectivity toward SO2 gas.