Multi-walled Carbon Nanotubes Composite Material Research Articles

Fabrication of NiCo2S4 accumulated on metal organic framework nanostructured with multiwalled carbon nanotubes composite material for supercapacitor application

Sonication-supported hydrothermal process was used to synthesize nanoporous carbon composites of NiCo2S4@N−MWCNT and NiCo2S4@N−MWCNT/MOF67 for supercapacitor applications. The structural, morphological, and electrochemical properties of the synthesized composites were improved the use of the hydrothermal process. The composite electrodes were assembled via three-electrode configuration using 6 M KOH as electrolyte solution. The NiCo2S4@N−MWCNT and NiCo2S4@N−MWCNT/MOF-67 composites showed the specific capacitance of (254 and ∼455) F/g, respectively, at 1 A/g. Due to the incorporation of the metal organic framework nano porous structured composite, the increment of the specific capacitance was almost 1.78-fold. The electrode shows excellent capacitance retention of 98.43% and improved the cyclic stability in presence of 6 M KOH electrolyte.

Recent developments in RAM based MWCNT composite materials: a short review

The need to develop radar absorbing materials (RAMs) that meet the structural requirement of defense applications is growing swiftly, due to the extensive use of electromagnetic waves in Radar. With the major developments and extensive use of Radar in military applications, the role of Radar absorbing, light weight and high strength structures has become a prime objective for researcher working on the development of RAMs. Various composites have been developed by using reinforcements which are dielectric, such as carbon nanotubes (CNT), magnetic materials like ferrites, that have been extensively used for reinforcement when developing RAMs. Ferromagnetic materials have a high density and can only achieve a narrow bandwidth of absorption. CNT have very good electrical, mechanical and thermal properties and can achieve high dielectric losses but their complex synthesis process is a barrier to commercial applications. Research on reinforcing multi-walled carbon nanotubes (MWCNT) with ferrites and metal oxides can also be extended to the study of thermoplastic polymers like polyether ether ketone and polyaryletherketone, which are gaining prominence in aeronautical applications, owing to their superior mechanical and low moisture absorbing properties. Further research can be carried out on reinforcing metal oxides, as metal oxides, when reinforced with MWCNT enhance the dielectric properties which improve the reflection losses as reported in a few studies.

Robust, flexible, freestanding and high surface area activated carbon and multi-walled carbon nanotubes composite material with outstanding electrode properties for aqueous-based supercapacitors

This novel carbon–carbon composite electrode has superlative electrochemical properties with flexibility, mechanical robustness, and weldability.

Pseudo-capacitive behavior of multi-walled carbon nanotubes decorated with nickel and manganese (hydr)oxides nanoparticles

We report on the synthesis, characterization of nickel hydroxide and manganese oxide nanoparticles decorating multiwalled carbon nanotubes composite material, and electrochemical performance for energy storage processes in symmetric electrochemical capacitors. A large pseudocapacitive voltage range of 1.7 V is presented using a coin cell containing a 1.0 M Li2SO4 aqueous solution, resulting in a maximum specific capacitance of ~ 420 F g−1 verified at 1.67 A g−1 during the discharge process. The symmetric coin cell was highly stable with a very high coulombic efficiency of ~ 99% even after 70,000 cycles of charge-discharge. The high electrochemical stability of coin cell was attributed to a synergism between the nanostructured carbon support and metal (hydr)oxides nanoparticles, i.e., the transport of electrons and ions across the porous electrode structure enables with a high degree of reversibility for the solid-state redox transitions reactions, which is the main contribution to the whole electrode specific capacitance. Near-surface structural changes of the electrodes were monitored during dynamic polarization by Raman and XRD synchrotron measurements. The presence of the active Ni–O stretching mode was verified during the charge-discharge processes according to the reversible solid-state redox process. The Raman shifts were also correlated with the reversible intercalation-deintercalation processes of Li+-ions into the MnOx host material, as well as reversible adsorption of solvated ions on the surface defects of carbon nanostructures.

An experimental investigation of using carbon foam–PCM–MWCNTs composite materials for thermal management of electronic devices under pulsed power modes

The present article reports on a detailed experimental investigation of using carbon foam–PCM–MWCNTs composite materials for thermal management (TM) of electronic devices subjected to pulsed power. The TM module was fabricated by infiltrating paraffin wax (RT65) as a phase change material (PCM) and multi walled carbon nanotubes (MWCNTs) as a thermal conductivity enhancer in a carbon foam as a base structure. Two carbon foam materials of low and high values of thermal conductivities, CF20 and KL1-250 (3.1 and 40 W/m K), were tested as a base structure for the TM modules. Tests were conducted at different power intensities and power cycling/loading modes. Results showed that for all power varying modes and all carbon foams, the infiltration of RT65 into carbon foam reduces the temperature of TM module and results in damping the temperature spikes height. Infiltration of MWCNTS into RT65 further improves the effectiveness of TM module. Temperature damping was more pronounced in stand-alone pulsed power cycles as compared to pulsed power spikes modes. The effectiveness of inclusion of RT65 and RT65/MWCNTs in damping the temperature spikes height is remarkable in TM modules based on KL1-250 as compared to CF-20.

Ultrafast Nanocrystalline-TiO2 (B)/Carbon Nanotube Hyperdispersion Prepared via Combined Ultracentrifugation and Hydrothermal Treatments for Hybrid Supercapacitors.

Anisotropically grown (b-axis short) single-nano TiO2 (B), uniformly hyper-dispersed on the surface of multiwalled carbon nanotubes (MWCNT), was successfully synthesized via an in situ ultracentrifugation (UC) process coupled with a follow-up hydrothermal treatment. The uc-TiO2 (B)/MWCNT composite materials enable ultrafast Li(+) intercalation especially along the b-axis, resulting in a capacity of 235 mA h g(-1) per TiO2 (B) even at 300C (1C = 335 mA g(-1) ).

Amino and thiol modified magnetic multi-walled carbon nanotubes for the simultaneous removal of lead, zinc, and phenol from aqueous solutions

The novel functionalization of multi-walled carbon nanotubes (MWCNTs) was synthesized by reacting trimethoxysilylpropanethiol (MPTs), hydrazine, ammonium ferrous sulfate, and ammonium ferric sulfate in sequence as efficient ways to introduce Fe3O4, amino and thiol groups onto the nanotubes sidewalls. The magnetic MWCNTs composite material (N2H4–SH–Fe3O4/o-MWCNTs) was characterized by transmission electron microscopy, field emission scanning electron microscopy, X-ray diffraction, thermo-gravimetric analysis, x-ray photoelectron spectroscopy, Fourier transformation infrared spectroscopy and magnetization curve. The results revealed that MPTs and hydrazine were coated on the surface of N2H4–SH–Fe3O4/o-MWCNTs. A series of batch adsorption experiments were conducted to study the experimental conditions, such as pH, contact time, initial concentrations and temperatures, which affected the adsorption process. The adsorption experiment results showed that the maximum equilibrium adsorption capacity of N2H4–SH–Fe3O4/o-MWCNTs for lead, zinc and phenol was 195.81mg/g, 169.89mg/g and 38.97mg/g at pH 6, respectively. The adsorption isotherm was better fitted by the Freundlich model, and the adsorption kinetics was consistent with pseudo-second order kinetics model. Furthermore, thermodynamic data showed that the adsorption process was spontaneous and exothermic. These results indicated that N2H4–SH–Fe3O4/o-MWCNTs may be promising surface modified materials for removing heavy metal ions and phenol from aqueous solutions.

Synthesis of Pt/PEI–MWCNT composite materials on polyethyleneimine-functionalized MWNTs as supports

Composite materials with highly dispersed platinum (Pt) nanoparticles on multiwalled carbon nanotubes (MWCNTs), functionalized with polyethyleneimine (PEI) by a noncovalent method were prepared. The PEI-functionalization provided high density homogeneous functional groups on the MWCNTs’ sidewalls for binding Pt nanoparticles. Cationic PEI leads to homogeneous dispersion in solutions such as water and organic solvents. The effects of a reducing agent on the Pt nanoparticles that form on the surfaces of the MWCNT were studied by varying the molar ratio of NaOH to H 2PtCl 6. These composite materials were characterized with transmission electron micrograph (TEM), X-ray diffractometer (XRD) and X-ray photoelectron spectroscopy (XPS). The Pt/PEI–MWCNT catalyst exhibits excellent electrocatalytic activity and compared with Pt/PVP–MWCNT catalysts obtained with polyvinylpyrrolidone (PVP). Finally, the cyclic voltammogram of methanol electrooxidation for Pt/PEI–MWCNT shows better tolerance to CO and methanol oxidation to CO 2 than of Pt/PVP–MWCNT.

Effect of molecular weight of polymer matrix on the dispersion of MWNTs in HDPE/MWNT and PC/MWNT composites

In this study, the effect of the molecular weight of the polymer matrix on the dispersion of multi-walled carbon nanotubes (MWNTs) was investigated for high-density polyethylene (HDPE)/MWNT and polycarbonate (PC)/MWNT composite materials. The dispersion of MWNTs in the polymer matrix showed a strong correlation with the melt viscosity of the polymer matrix, i.e., with the molecular weight of the polymer material. Several experimental methods, such as 4-point probe, SEM and ARES, were used to examine the effect of the molecular weight of the polymer matrix on the dispersion of the MWNTs and various physical properties of the composites. The use of a high melt viscosity polymer as the matrix material restricted the mobility of the MWNTs, and also hindered the dispersion of MWNTs due to the high entanglement density of the polymer matrix.

Improvement of cycle property of sulfur-coated multi-walled carbon nanotubes composite cathode for lithium/sulfur batteries

A novel sulfur-coated multi-walled carbon nanotubes composite material (S-coated-MWCNTs) was prepared through capillarity between the sulfur and multi-walled carbon nanotubes. The results of the TEM and XRD measurements reveal that S-coated-MWCNTs have a typical core-shell structure, and the MWCNTs serve as the cores and are dispersed individually into the sulfur matrices. The charge–discharge experiments of the lithium/sulfur cells demonstrated that the S-coated-MWCNTs cathode could maintain a reversible capacity of 670 mAh g −1 after 60 cycles, showing a greatly enhanced cycle ability as compared with the sulfur cathode with simple MWCNTs addition (S/MWCNTs) and the cathode using sulfur-coated carbon black composite (S-coated-CB). The EIS and SEM techniques were used to define and understand the impact of the microstructure of the composite electrode on its electrochemical performance. Derived from these studies, the main key factors to the improvement in the cycle life of the sulfur cathode were discussed.