Optimal thickness of the catalytic nickel coating for the CVD synthesis of carbon nanomaterials

Sokolowski K., Palka P., Blazewicz S., Fraczek- Szczypta A.

The subject of the study were nanocomposites made by infiltration of carbon nanofibers in the form of mat (CNF) with a poly(methylphenylsiloxane) resin (PMPS) solution followed by heat-treatment up to 1000 °C. The nanocomposites were studied using scanning electron microscopy (SEM-EDS), X-ray diffraction (XRD), Raman spectroscopy and by means of surface measurement tests. The morphology, microstructure, structure and selected properties of the nanocomposites were analysed. The influence of the CNF oxidative surface treatment on interface properties in CNF/resin and CNF/resin-derived ceramics nanocomposites was investigated. The high surface tension occurring at the nanofiber/resin interface required preliminary chemical treatment of carbon nanofiber surface. The surface chemical state of CNF had a significant influence on their interaction with the resin and formation of SiOC protective layer on nanofibers surface. The SiOC phase formed on the CNF surface at 1000 °C improved thermal stability of the nanocomposites in air. Due to the formation of the free carbon phase during resin heat-treatment the resulting ceramic nanocomposite matrix showed a lower electrical resistance compared to pure carbon mats.

Igbokwe E.C., Daramola M.O., Iyuke S.E.

Effect of synthesis temperature on the structure, morphology and crystallinity of as-synthesized CNT yarns via direct spinning was studied using Raman spectroscopy, x-ray powder diffraction (XRD) and thermogravimetric analysis (TGA). Effects of synthesis temperature on purity, morphology and thermal stability were related to the conductivity of the CNT yarns. It was observed that increase in synthesis temperature increased the sp2 content of the as-synthesized carbon nanotubes yarns as indicated by the decrease in ID/IG ratio and increase in oxidation temperature. Current-Voltage (I-V) relationship for the CNT yarns synthesized at 1000 °C indicates an increase in resistivity with increased applied voltage, indicating promising potential of the produced yarns as filaments for incandescent bulbs.

Youssry M., Kamand F.Z., Magzoub M.I., Nasser M.S.

Optimal hybrid dispersion of carbon black (CB) and nanofibers (CNFs) is formed at a critical content of CNFs before its aggregation concentration so that CNFs wire CB aggregates to recover the conductivity loss without increasing of CB rigidity.

Sukanya R., Sakthivel M., Chen S., Chen T.

A new type of terbium diselenide (Tb2Se2) was prepared in the structure of nano octagon and integrated with oxidized carbon nanofiber (f-CNF) by using a simple hydrothermal technique. The oxidation of CNF and the formation of f-CNF/Tb2Se2 nanocomposite were studied by using various analytical techniques such as TEM, FT-IR, Raman, XRD and XPS analysis. In addition, the electrochemical properties of f-CNF/Tb2Se2 nanocomposite modified glassy carbon electrode (GCE) were studied by using the electrochemical techniques such as CV and DPV techniques, which showed low charge transfer resistance (Rct = 7.26 Ω) and high active surface area (A = 0.113 cm2). Meanwhile, the CV of ferricyanide at this electrode showed a low peak potential separation (ΔEp = 0.060 V). Furthermore, the reported f-CNF/Tb2Se2/GCE exhibited an excellent electrochemical activity towards the detection of morin. As expected, f-CNF/Tb2Se2/GCE exhibited high sensitivity (1.07 μA μM−1 cm−2) and acceptable detection limit (0.6 μM) of morin. In addition, f-CNF/Tb2Se2/GCE was found with feasible selectivity, stability, and reproducibility. Finally, the real sample analysis also stated the exclusive performance of f-CNF/Tb2Se2/GCE electrode towards the detection of morin in guava leaves extract.

Rudakov G.A., Sosunov A.V., Ponomarev R.S., Khenner V.K., Reza M.S., Sumanasekera G.

This work is devoted to the study of the synthesis, the description of the structure, and the use of hollow carbon nanoshells 3–5 nm in size. Hollow carbon nanoshells were synthesized by thermolysis of a mixture of nickel acetate and citric acid in the temperature range of 500–700°C. During the chemical reaction, nickel nuclei ~3–5 nm in size are formed, separated from each other by carbon layers. At an annealing temperature of 600°C, the most ordered, close-packed structure is formed, evenly distributed throughout the sample. The etching of nickel with nitric acid resulted in hollow carbon nanoshells with a high specific surface area (~1200 m2/g) and a homogeneous structure. Raman spectroscopy shows that the graphene-like structure of carbon nanoshells is preserved before and after the etching of nickel, and their defect density does not increase, which enables them to be subjected to new processing (functionalization) in order to obtain additional physical properties. The resulting carbon nanoshells were used as active material of the supercapacitor electrodes. The conducted electrochemical measurements showed that the specific capacitance of the supercapacitor did not fall below 120 F/g at a current density of 0.3 to 3 A after 800 charge/discharge cycles.

Asmaly H.A., Abussaud B., Ihsanullah, Saleh T.A., Gupta V.K., Atieh M.A.

In this work, ferric oxide nanoparticle decorated carbon fibers and carbon nanotubes (CNF/Fe 2 O 3 and CNT/Fe 2 O 3 ) were synthesized and characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), X-ray diffraction (XRD), zeta potential and BET surface area analyzer. The prepared nanocomposites were evaluated or the removal of phenol ions from aqueous solution. The effects of experimental parameters, such as shaking speed, pH, contact time, adsorbent dosage and initial concentration, were evaluated for the phenol removal efficiency. The adsorption experimental data were represented by both the Langmuir and Freundlich isotherm models. The Langmuir isotherm model best fitted the data on the adsorption of phenol, with a high correlation coefficient. The adsorption capacities, as determined by the Langmuir isotherm model were 0.842, 1.098, 1.684 and 2.778 mg/g for raw CNFs, raw CNTs, CNF–Fe 2 O 3 and CNT–Fe 2 O 3 , respectively.

Danilova-Tret’yak S.M., Evseeva L.E., Tanaeva S.A.

Experimental investigations of the thermophysical properties of traditional and modified asbestos-reinforced laminates depending on the type of their carbon nanofiller have been carried out in the range of temperatures from –150 to 150°C. It has been shown that the largest (nearly twofold) increase in the thermal-conductivity and thermal-diffusivity coefficients of the indicated materials is observed when they are modified with a small-scale fraction of a nanofiller (carbon nanotubes). The specific heats of the modified and traditional asbestos-reinforced laminates turned out to be identical, in practice, within the measurement error.

Grinchuk P.S., Kiyashko M.V., Stankevich Y.A., Fisenko S.P.

Experimental results on the dynamics of filling and displacement of the gases from a flow reactor by a mixture of oxygen and nitrogen at different wall temperatures have been given. It has been established that when the wall temperature is high, the processes of filling and displacement are much more rapid at all flow rates. A similarity parameter of the problem, which is equal to the ratio of the characteristic times of convective and diffusion processes, has been introduced. An analytical representation in the form of a Pade approximant has been obtained for the characteristic mixing time.

Liu Y., Ba H., Nguyen D., Ersen O., Romero T., Zafeiratos S., Begin D., Janowska I., Pham-Huu C.

The macroscopic shaping of carbon nanostructure materials with tunable porosity, morphologies, and functions, such as carbon nanotubes (CNT) or carbon nanofibers (CNF), into integrated structures is of great interest, as it allows the development of novel nanosystems with high performances in filter applications and catalysis. In the present work, we report on a low temperature chemical fusion (LTCF) method to synthesize a self-macronized carbon nanotubes foam (CNT-foam) with controlled size and shape by using CNT as a skeleton, dextrose as a carbon source, and citric acid as a carboxyl group donor reacting with the hydroxyl group present in dextrose. The obtained composite has a 3D pore structure with a high accessible surface area (>350 m2 g−1) and tunable meso- and macro-porosity formed by the addition of a variable amount of ammonium carbonate into the starting mixture followed by a direct thermal decomposition. The as-synthesized CNT-foam also exhibits a relatively high mechanical strength which facilitates its handling and transport, while the nanoscopic morphology of the CNT significantly reduces the problem of diffusion and contributes to an improvement of the effective surface area for subsequent applications. These CNT-foams are successfully employed as selective and recyclable organic absorbers with high efficiency in the field of waste water treatment.

Bedewy M., Meshot E.R., Hart A.J.

We reveal that the collective growth of vertically aligned carbon nanotube (CNT) forests by chemical vapor deposition (CVD) is governed by the size-dependent catalytic behavior of metal nanoparticles, which can be quantitatively related to the activation and deactivation kinetics of subpopulations of CNTs within the forest. We establish this understanding by uniquely combining real-time forest height kinetics with ex situ synchrotron X-ray scattering and mass-attenuation measurements. The growing CNT population is divided into subpopulations, each having a narrow diameter range, enabling the quantification of the diameter-dependent population dynamics. We find that the mass kinetics of different subpopulations are self-similar and are represented by the S-shaped Gompertz model of population growth, which reveals that smaller diameter CNTs activate more slowly but have longer catalytic lifetimes. While competition between growth activation and deactivation kinetics is diameter-dependent, CNTs are held in contact by van der Waals forces, thus preventing relative slip and resulting in a single collective growth rate of the forest. Therefore, we hypothesize that mechanical coupling gives rise to the inherent tortuosity of CNTs within forests and possibly causes structural defects which limit the properties of current CNT forests in comparison to pristine individual CNTs.

Abuhimd H., Uddin G.M., Zeid A., Jung Y.J., Kamarthi S.

Chemical vapor deposition is one of the several viable methods for growing vertically aligned single-walled carbon nanotubes (VA-SWNTs). Utilizing cobalt (Co) catalyst supported on multilayer Al/SiO2 and a hydrocarbon feedstock, VA-SWNTs are grown in excess of a millimeter height. To control VA-SWNTs length, one has to use the right combination of process control variables such as hydrocarbon gas flow rate, chamber temperature, and chamber pressure. This paper presents a process meta-model-based full factorial experimental design and analysis to study the yield of tall VA-SWNTs. All of the process variables under the study play a role in influencing VA-SWNTs length; the current study investigates main effects and their interactions. The meta-model-based analysis demonstrates that the hydrocarbon flow rate and the chamber pressure are the most statistically significant control variables that influence the length of VA-SWNTs. In addition, the response surface graph confirms that a higher gas flow rate at lower chamber pressure will consistently yield tall VA-SWNTs. We found that gas flow rate is the most significant of the control variables and only the optimum gas flow rate can ensure the growth of tall VA-SWNTs. We noticed that the interaction of gas flow rate with chamber temperature is also significant to the length of VA-SWNTs grown. All these observations together indicate that the dynamic pressure of the gas in the chamber plays an important role in the assurance of the length of VA-SWNTs. Outcomes of this investigation are beneficial for moving us closer towards producing VA-SWNTs on a mass scale.

Glebova N.V., Nechitailov A.A., Kukushkina Y.A., Sokolov V.V.

The process of the thermal oxidation of various carbon nanomaterials (multiwalled carbon nanotubes, carbon black, nanoporous carbon and graphite) used in the catalytic layers of electrochemical energy converters (electrolyzers, fuel cells) has been studied. The thermal stability of these materials has been determined. Relationships between the structural characteristics of carbon nanomaterials and the parameters of their thermal oxidation in air have determined using the methods of differential thermal analysis and adsorption-structure analysis.

Lukvich A.A., Bulatov O.V.

The resolution and range of measurements of the thicknesses of nickel coatings on steels with different properties were investigated using magnetic methods. The magnetization of nickel coatings was calculated as a function of their thickness, their primary magnetic field, and the properties of their bases. The requirements for parameters of magnetodynamic transducers that allow the minimization of the error that is attributed to coating structure, maximal resolution, and the ranges of measurements for different combinations of base and coating properties were determined.

Pacheco Benito S., Lefferts L.

Carbon nanofibers (CNFs) were deposited on metal foils including nickel (Ni), iron (Fe), cobalt (Co), stainless steel (Fe:Ni; 70:11 wt.%) and mumetal (Ni:Fe; 77:14 wt.%) by the decomposition of C 2 H 4 at 600 °C. The effect of pretreatment and the addition of H 2 on the rate of carbon formation, as well the morphology and attachment of the resulting carbon layer were explored. Ni and mumetal show higher carbon deposition rates than the other metals, with stainless steel and Fe the least active. Pretreatment including an oxidation step normally leads to higher deposition rates, especially for Ni and mumetal. Enhanced formation of small Ni particles by in situ reduction of NiO, compared to formation using a Ni carbide, is probably responsible for higher carbon deposition rates after oxidation pretreatment. The addition of H 2 during the CNF growth leads to higher carbon deposition rates, especially for oxidized Ni and mumetal, thus enhancing the effect of the reduction of NiO. The diameters of CNFs grown on metal alloys are generally larger compared to those grown on pure metals. Homogenously deposited and well-attached layers of nanotubes are formed when the carbon deposition rate is as low as 0.1–1 mg cm −2 h −1 , as mainly occurs on stainless steel.

Escobar M., Giuliani L., Candal R.J., Lamas D.G., Caso A., Rubiolo G., Grondona D., Goyanes S., Márquez A.

Fil: Escobar, M.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Fisica; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Quimica Inorganica, Analitica y Quimica Fisica; Argentina

Lan W., Zhou Y., Liu J., Wang Y., Jin X., Yin D., Ji J., Yang G., Zhang H.

Akçay S.B., Kocaman M., Çelebi M., Güler O., Varol T.

While studies on the incorporation of metal particles into the epoxy matrix are quite common, this research introduces a novel approach by incorporating electroless Ni-coated Cu particles with functional features into the epoxy matrix. Thus, it presents an innovative investigation of epoxy composites with enhanced both thermal and mechanical properties. Therefore, three samples of pure epoxy, dendritic Cu particle reinforced (20 wt%), and electroless Ni-coated dendritic Cu particle reinforced (20 wt%) epoxy composites were fabricated by mixing followed by casting into the mold. The epoxy and composite specimens underwent phase analysis through XRD, and morphological examinations were conducted using SEM equipped with an EDS analyzer, respectively. The hardness, tensile, and bending tests were conducted for mechanical characterization. To evaluate the thermal properties, DSC and TGA tests were employed to assess the impact of the Cu and the electroless Ni-coated Cu particles on the thermal stability of the composites. The mechanical analysis results showed that the pure epoxy sample had tensile and flexural strengths of 23.2 MPa and 43 MPa, respectively. These values increased significantly by 90 % and 311 % in the presence of Ni-coated dendritic Cu particles, reaching 54 MPa and 177 MPa, respectively. Thermal analysis results indicated that the Tg increased with the incorporation of dendritic Cu particles and Ni-coated dendritic Cu particles. Furthermore, the highest thermal conductivity was observed in the Cu-reinforced composites.

Feng Y., Jiang J., Xu Y., Wang S., An W., Chai Q., Prova U.H., Wang C., Huang G.

With the emerging requirement for clean renewable energy and storage system, the advancement of ecofriendly, low-cost, highly active electrode materials has expanded. Biomass, as a natural abundant, renewable source with diverse structure serves as an alternative sustainable source. Recent studies demonstrated that various applications of biomass-derived carbon materials are currently prevailing in electrocatalysis and energy storage and conversion system due to their tunable structure, multiple porosity and rich surface chemistry. Here, in this review, we primarily focus on the principal synthetic strategies of biomass-derived carbon including pyrolysis, hydrothermal carbonization, chemical vapor deposition, molten salt carbonization, template method along with the assist of microwave and ultrasonication approach. Then, this review strives to highlight the recent development of various dimensions of biomass-derived carbon nanostructure ranging from zero-dimensional carbon dots, one-dimensional carbon nanotubes/fibers/wires, two-dimensional carbon nanosheets to three-dimensional hierarchical carbon in view of pore size and surface area. We also summarize the primary application of biomass-based carbon nanostructure in versatile electrocatalysis, various kinds of secondary batteries, supercapacitors, and other energy related storage fields. Finally, challenges in the development of biomass-based carbon and the large-scale production in industrial fields are addressed.

Guha S., Das S.

In this work, chemically vapor deposited TiCN coating consists of crack network over the surface with higher C content due to the impingement of higher amount of nitrogen gas over it. The surface morphology analysis by AFM suggests that with higher C content particles distribution density of TiCN coating changes abruptly due to the presence of small or tiny particles in between large particles. Irrespective of C content the relation between Ra and indentation modulus is found to be nonlinear as 1–3% scattering being observed. The microstructure analysis by XRD confirms that the TiCN is multiphase material with the presence of crystalline phase at (111), (200) and (220) crystal planes and graphite phase at ~ 52°. As the corrosion potential (Ecorr values) has been shifted toward the negative side hence corrosion resistance of TiCN coating reduces with higher C content. The higher C content improves the crystal quality of TiCN coating as the peak position of different phonon modes are blue shifted. The mechanical property analysis suggests that with higher C content the preferred growth orientation has been formed and this ultimately improves the mechanical properties.

Hansa, Sahani S., Kim T.

Environmental and Energy issues are the two major issues that our world is confronting nowadays. Utilitarian nanocomposites are rising materials for zillions of Energy and environmental applications. Nanomaterials are a different class of materials composed of metal, metal oxides/sulfides/phosphides (nanostructured and thin films) varying in levels of electronic structure, physical, chemical, and electromagnetic properties. There are several alkaline and alkali earth metal-based nanocomposites that are used in basic heterogeneous catalysis for cleaner fuel production. Whereas transition metal/metal oxide-based nanocomposites (TMMONs) like ZnO, TiO2, SnO2, ZrO2, and Fe3O4 are gaining tremendous attention as photocatalysts. Moreover, these transition metal/metal oxide-based nanocomposites consist of lucrative flexible mechanical properties along with extraordinary electrochemical performance to fabricate the natural observing gadgets. Recently, these TMMONs have been majorly employed as active electrodes in electrochemical cells and supercapacitors due to their excellent dielectric properties and high porosity. Even, nanocomposites of metals with carbon-based materials have got a lot of potential in energy storage applications due to their fast power energy delivery, long lifecycle, high power density, besides reasonably high energy density that can fill the gap between the batteries and the conventional capacitors. In this book chapter, we would thoroughly discuss the above-mentioned aspects of various metal/metal oxides-based nanocomposites employed in energy and environmental application.