Dispersion Of Carbon Nanoparticles Research Articles

Enhanced Thermal Properties of Phase Change Materials through Surfactant-Functionalized Graphene Nanoplatelets for Sustainable Energy Storage

Phase change materials (PCMs) are increasingly gaining prominence in thermal energy storage due to their impressive energy storage capacity per unit volume, especially in applications with low and medium temperatures. Nevertheless, PCMs have significant limitations regarding their ability to conduct and store heat, primarily due to their inadequate thermal conductivity. One potential solution for improving the thermal conductivity of PCMs involves the inclusion of nanoparticles into them. However, a recurring issue arises after several thermal cycles, as most nanoparticles have a tendency to clump together and settle at the container’s base due to their low interfacial strength and poor compatibility. To address this challenge, including surfactants such as sodium dodecylbenzene sulfonate (SDBS) has emerged as a prevalent and economically viable approach, demonstrating a substantial impact on the dispersion of carbon nanoparticles within PCMs. The foremost objective is to investigate the improvement of thermal energy storage by utilizing graphene nanoplatelets (GNP), which are dispersed in A70 PCM at various weight percentages (0.1, 0.3, 0.5, 0.7, and 1.0), both with and without the use of surfactants. The findings indicate a remarkable enhancement in thermal conductivity when GNP with surfactants is added to the PCM, showing an impressive increase of 122.26% with a loading of 1.0 wt.% compared to conventional PCM. However, when 1.0 wt.% pure GNP was added, the thermal conductivity only increased by 48.83%. Additionally, the optical transmittance of the composite containing ASG-1.0 was significantly reduced by 84.95% compared to conventional PCM. Furthermore, this newly developed nanocomposite exhibits excellent stability, enduring 1000 thermal cycles and demonstrating superior thermal and chemical stability up to 257.51 °C. Due to its high thermal stability, the composite NePCM is an ideal candidate for preheating in industrial and photovoltaic thermal (PVT) applications, where it can effectively store thermal energy.

Enhancement of polypropylene mechanical behavior by the synergistic effect of mixtures of carbon nanofibers and graphene nanoplatelets modified with cold propylene plasma

AbstractIncorporating carbon nanoparticles (CNPs) into polymers can enhance their mechanical behavior; however, enhancement depends strongly on compatibility and homogeneous dispersion. Actual methods to succeed high dispersion and compatibility are complicated, have solvent‐associated problems, and long processing times. The present work proposes the increase of the dispersion and compatibility of CNPs in a polypropylene (PP) matrix to obtain a nanocomposite with high mechanical properties, using simple, fast, and green methodologies: the modification of the CNPs by cold propylene plasma and the synergistic effect resulting from mixtures of carbon nanofibers (CNFs) and graphene nanoplatelets (GNPs) with PP matrix by melt mixing. Mixtures of CNFs and GNPs in 9:1, 8:2, and 7:3 ratios at 1 and 5 wt/wt% with and without surface modification by cold propylene plasma were fabricated. The compatibility and dispersion of the CNPs in the PP matrix were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy, and the results were related to the mechanical properties. The results show that the use of mixtures improved the dispersion in the system and hindered the reagglomeration of CNPs, whereas surface modification with plasma promotes higher compatibility between the phases. The elastic modulus of PP reached an increase of 127.40% using a modified mixture by plasma in a 7:3 ratio (CNF:GNPs) at 5 wt/wt%, while when the CNPs were used individually, the modified CNFs and GNPs at 5 wt/wt%, reached 97.77% and 111.85%, respectively. In addition, a finite element analysis shows that the stresses in nanocomposites fabricated with mixtures of CNPs are supported to a greater extent by GNPs than CNFs due to their morphology with a low number of graphene sheets, which allows them to have greater flexibility.

Effect of pulmonary surfactant on the dispersion of carbon nanoparticles

Carbon nanoparticles (CNs) are widely used and there has been a great concern about their potential adverse effects on human health. CNs can directly interact with the pulmonary surfactant (PS) lining of alveoli, but the dispersion state of CNs at PS film has not yet been explored. Accumulating evidences indicated that the degree of dispersion of nanoparticles has a strong influence on their biological activities. This study investigated the effect of PS and its major components on the dispersion state of three representative CNs (fullerene C60, nano carbon powder, graphene oxide). The results demonstrated that suspended concentrations of all three CNs were lower in the presence of PS and its lipid component dipalmitoylphosphatidylcholine (DPPC) than in the presence of bovine serum album (BSA). Compared with PS and DPPC, BSA notably reduced the hydrodynamic diameters of CNs. In addition, the absolute zeta potentials of CNs in the presence of BSA was higher than those in the presence of PS or DPPC, and this result corresponds to the increase of surface oxygen contents of CNs, indicating that relatively high surface oxygen content is beneficial for the dispersion of CNs in alveolus. π-A isotherms demonstrated that the surface tension and phase behavior of PS were obviously altered in the presence of CNs. This study revealed the role of PS and different active components in the dispersion of CNs, which is helpful for deeply understanding CNs alveolar transport and the associated potential hazards to lung health. • Interaction of PS with carbon nanoparticles (CNs) leads to the aggregation of CNs. • Lipids and protein components of PS exert different effects on CNs dispersion. • Hydrodynamic diameter/zeta potential impact the dispersion of CNs with PS component. • Surface oxygen content of CNs governs the dispersion of CNs. • CNs exposure leads to the alternation of phase behavior of PS film.

Triple graphite nitrate cointercalation compounds with acetic acid as precursors for thermally expanded graphite and carbon nanoparticles

Triple graphite nitrate cointercalation compounds (GNCCs) with acetic acid were synthesized, characterized by powder XRD and SEM methods, and used as a source of the thermally expanded graphite (TEG). Structural reorganization of graphite nitrate-acetate and triple GNCCs with acetic acid as a result of their exposition in air is discussed on the base of powder XRD data. Dispersions of carbon nanoparticles were prepared by liquid phase exfoliation of TEGs obtained from the GNCCs. It was demonstrated by TEM method that using of the studied TEGs as a source of carbon nanoparticles favours formation of few-layered graphene.

Quality over Quantity: How Different Dispersion Qualities of Minute Amounts of Nano-Additives Affect Material Properties in Powder Bed Fusion of Polyamide 12.

The great interest, within the fields of research and industry, in enhancing the range and functionality of polymer powders for laser powder bed fusion (LB-PBF-P) increases the need for material modifications. To exploit the full potential of the additivation method of feedstock powders with nanoparticles, the influence of nanoparticles on the LB-PBF process and the material behavior must be understood. In this study, the impact of the quantity and dispersion quality of carbon nanoparticles deposited on polyamide 12 particles is investigated using tensile and cubic specimens manufactured under the same process conditions. The nano-additives are added through dry coating and colloidal deposition. The specimens are analyzed by tensile testing, differential scanning calorimetry, polarized light and electron microscopy, X-ray diffraction, infrared spectroscopy, and micro-computed tomography. The results show that minute amounts (0.005 vol%) of highly dispersed carbon nanoparticles shift the mechanical properties to higher ductility at the expense of tensile strength. Despite changes in crystallinity due to nano-additives, the crystalline phases of polyamide 12 are retained. Layer bonding and part densities strongly depend on the quantity and dispersion quality of the nanoparticles. Nanoparticle loadings for CO2 laser-operated PBF show only minor changes in material properties, while the potential is greater at lower laser wavelengths.

Synthesis and Properties of Graphite Nitrate Cointercalation Compounds with Carboxylic Acid Esters

To expand the number of possible precursors of carbon nanoparticles, i.e., low-layer graphenes and nanoscrolls, binary and ternary graphite nitrate cointercalation compounds (GNCCs) with formic and acetic acid esters have been synthesized. X-ray powder diffraction data have demonstrated that the obtained GNCCs are stage II and IV intercalation compounds. It has been shown that the use of ethyl formate or an ethyl acetate/butyl acetate mixture as organic cointercalants leads to an increase in the height of the layer filled with intercalants as compared with graphite nitrate. Dispersions of carbon nanoparticles (low-layer graphenes and nanoscrolls) were obtained by sonication-assisted liquid-phase exfoliation of studied GNCCs in ethanol. The morphology of the obtained nanoparticles has been studied by transmission electron microscopy.

Synthesis, Characterization and Mechanical Properties of Nanocomposites Based on Novel Carbon Nanowires and Polystyrene

Carbon into polymer nanocomposite is so far a common additive for the enhancement of the polymer properties. The properties of the polymer, such as thermal, and especially its mechanical properties, are improved by the homogeneously dispersed carbon nanoparticles on the polymer matrix. In this study, carbon wires in nano dimensions are, for the very first time, synthesized via the hard templating method from the silicate matrix MCM-41, and used as nano additives of polystyrene. The carbon nanowires were chemically oxidized, and further modified by attaching octadecylamine molecules, for the development of organic functionalities onto carbon nanowires surface. The nanocomposite materials of polystyrene with the modified carbon nanowires were prepared by a solution-precipitation method at three nano additive to polymer loadings (1, 3 and 5 wt%). The as-derived nanocomposites were studied with a combination of characterization and analytical techniques. The results showed that the thermal and mechanical properties of the polystyrene nanocomposites gradually improved while increasing nano-additive loading until 3 wt%. More specifically, the 3 wt% loading sample showed the best mechanical properties, while the 5 wt% sample was difficult to achieve satisfactory dispersion of carbon nanowires and consequently has a wide range of values.

Multi-walled carbon nanotubes functionalized silk fabrics for mechanical sensors and heating materials

MWCNTs@silk fabric (CSF) with single-side, good conductive property was prepared via a surface micro-dissolution strategy. In this method, the partial dissolution of silk fibers was regulated by the concentration formic acid and the interaction between the protein and its solvent. The dissolved silk protein served as the physical crosslinking agent that connected dispersed carbon nanoparticles to form a continuous conductive network, avoiding complex chemical treatments and the use of physical adhesives. CSF possessed good electrical conductivity (468 Ω cm−1) and durability. Moreover, CSF had a unique single-side loading characteristic and its resistance changed from 98.4% to 102% of the initial value with the bending angle varying from −112.5° to 112.5°, so CSF could be used as sensors to monitor the mechanical activities effectively. Patterned conductive MWCNTs@silk fabric (PCSF) was fabricated by using patterned templates during the deposition process and used for wider applications, such as flexible switches (F-shaped PCSF), soft keyboards (keyboard-like PCSF), electric heating materials (S-shaped PCSF) and microwave-assisted heating materials (butterfly-like PCSF).

Efficient oxygen reduction in a microbial fuel cell based on carbide-derived carbon electrode synthesized using thiourea as the single source of electroconductive heteroatoms and graphitic carbon

A novel one step method was developed to dope nitrogen (N), sulfur (S) and carbon (C) in the Fe nanoparticles-dispersed carbon nanofibers (CNFs) grown over carbide-derived carbon (CDC), using thiourea as the single source of N, S and C. The synthesized N/S-Fe-CNF/CDC electrode was successfully used in a microbial fuel cell (MFC). When tested as the oxygen reduction reaction (ORR) catalyst, the electrode achieved a high current density (2.261 ± 0.002 mA/cm2), high OCP (0.611 ± 0.005 V), high stability upto 400 cycles, response time of ∼11 s, electron transfer number in the range 3.73–4.03, and Tafel slopes of −0.0627 and −0.183 V/dec at low and high current densities, respectively. A first order kinetics and a 4e− pathway were deduced from the ORR analysis. Notably, the fabricated MFC based on the prepared electrode produced a high current density of 1.3887 ± 0.002 mA/cm2, high OCP of 0.626 ± 0.005 V and maximum power density of 0.238 ± 0.002 mW/cm2, attributed to the synergistic effects of heteroatoms, Fe nanoparticles, and CNFs.

Electrochemical CO2 reduction on copper nanoparticles-dispersed carbon aerogels

The conversion of CO2 into carbon-based fuels via electrochemical reduction is a promising approach to realizing the termination of carbon cycling. Copper (Cu0) is considered to be an effective electrochemical catalyst for such purpose. However, it is limited by its instability and low selectivity. In this work, Cu2+ was embedded into a polycondensation structure of resorcinol (R) and formaldehyde (F) via sol-gel reaction, and the complex was then calcined at high temperature to obtain copper nanoparticles-dispersed carbon aerogels (Cu/CA). The samples were further activated sequentially under CO2 and N2 atmosphere. The final products under different activation temperature of secondary N2 atmosphere were obtained and marked as Cu/CA-CO2-N2-T. The existence of highly dispersed Cu0 on the carbon aerogels was confirmed by XPS and HRTEM, which exhibited attractive activity towards electrochemical CO2 reduction reaction (CO2RR) forming carbon product in 0.1 M KHCO3 aqueous media. Furthermore, the CO2RR product distribution varied under different samples. The sample activated under 700 °C (Cu/CA-CO2-N2-700) with Cu loading c.a. 5.13 wt% showed remarkable CO faradaic efficiency (FE) (75.6%) at low overpotential of −0.49 V. Further calcination led to more exposure of copper, and CO dimerization to C2 product. The high selectivity toward CO by Cu/CA-CO2-N2-700 maybe attributed to their excellent stability in maintaining the metallic nature of Cu component within the hydrophobic carbon aerogels during electrocatalysis, which further prevents the adsorption and reduction of CO on the catalyst.

Frequency or Amplitude?-Rheo-Electrical Characterization of Carbon Nanoparticle Filled Epoxy Systems.

Dispersion of carbon nanoparticles in epoxy resin is the key factor to adjust the resulting electrical and mechanical properties of the nanocomposite. A profound understanding of the driving forces of standard methods like ultrasonic and mechanical dispersion is necessary. To derive the impact of applied frequency and strain on the resulting dispersion of multi-walled carbon nanotube (MWCNT)-filled epoxy resin, this work addresses the strain and frequency dependency of oscillatory shear flow-induced network changes. Strain- and frequency-sweeps were performed for a wide parameter set with in-line measurement of electrical DC resistance to monitor changes in the MWCNT network. Changes in electrical resistance reveal destruction and formation of the MWCNT network. A fundamental novel finding is the governing dependency of changes in the electrical network on applied shear amplitude. The applied frequency barely induces network changes. Applied shear rates do not correlate with particular network states.

Numerical study of ultrafine particles dispersion in the wake of a cylinder

The dynamics of ultrafine particles are strongly dependent to the air flow topology. In this study, the dispersion of carbon nanoparticles in the wake of a cylinder placed in an air flow at Reynolds number of 9300 is numerically investigated. An Eulerian/Lagrangian approach is used to compute the two-phase flow; the carrier phase is predicted through a RANS (Reynolds Averaged Navier-Stokes) model while a particle Lagrangian tracking method provides the trajectory of each nanoparticle. The present numerical investigation allows studying the influence of Brownian and turbulence effects on the nanoparticles dispersion. The main results reveal that: (1) The Brownian diffusion tends to concentrate the carbon nanoparticles in the form of a filament at the periphery of the vortices that are generated in the cylinder wake. (2) The turbulence increases the lateral dispersion of the nanoparticles. It disperses them from the edge to the core of the vortices. (3) The highest concentration levels decrease from the near wake of the cylinder to the far wake region while the lateral dispersion increases.

Simultaneous Cr(VI) reduction and bioelectricity generation using microbial fuel cell based on alumina-nickel nanoparticles-dispersed carbon nanofiber electrode

An alumina (AA)/nickel (Ni) nanoparticles (NPs)-dispersed carbon nanofiber (CNF)-based electrode was for the first time used in a mediatorless double-chambered microbial fuel cell (MFC) for the simultaneous electrochemical reduction of hexavalent chromium (Cr(VI)) in water and generation of bioelectricity. Whereas the AA NPs increased the electrical conductivity of the electrode, the Ni NPs served as the catalyst for growing the CNFs on an activated carbon microfiber substrate by chemical vapor deposition and for catalyzing the Cr(VI) reduction at the cathode. Such MFCs showed a complete removal of Cr(VI) at 100ppm-concentration, achieving a significantly high reduction rate of ∼2.13g/m3-h, besides generating electricity with the maximum power density of ∼1540mW/m2, open circuit potential of 900mV and cathodic columbic efficiency of 93%. The MFCs using the inexpensive transition metals-dispersed CNF electrode, prepared in this study, has the potential for the efficient treatment of the similar electron acceptor metals-laden wastewater, with the simultaneous generation of electricity.

Dispersion of carbon nanoparticle in water with poly(acrylic acid)-poly(amideimide) copolymers

The dispersion of carbon nanoparticles in water was investigated using dispersants based on block copolymers of poly(acrylic acid) (PAA) and poly(amideimide) (PAI) or a homopolymer of PAA. A diblock copolymer (PAA-block-PAI), triblock copolymer (PAA-block-PAI-block-PAA), and hetero-arm star block copolymer (PAA2PAI) with similar molecular weights and PAA contents were used as dispersants. The dispersion of solutions with these polymers was investigated by ζ-potential measurements and transmission electron microscopy. The adsorption of PAI onto carbon nanoparticles was observed. The dispersion of carbon nanoparticles was measured using dynamic light scattering and UV-vis spectroscopy. The dispersibility of carbon nanoparticles increased through the series of copolymers (from most to least dispersed): PAA2PAI, PAA-block-PAI, PAA-block-PAI-block-PAA, and homo-PAA. PAA-PAI copolymers behaved as effective dispersants for carbon nanoparticles in water. The presence of a hydrophobic block was essential for dispersion. The architecture of the block copolymers also influenced the dispersion of nanoparticles. Locally concentrated regions of PAA exhibited repulsive interactions, causing dispersion of nanoparticles. PAA2PAI demonstrated the greatest potential as an anode binder in lithium-ion batteries because it functioned as a dispersant for the conductive additive.

Optimization of dispersed carbon nanoparticles synthesis for rapid desulfurization of liquid fuel

Stringent regulations and environmental concerns make the production of clean fuels with low sulfur content compulsory for the petroleum refining industry. Because of ease of operation without high energy consumption, the adsorption of sulfur compounds seems the most promising process. Central composite design was used to optimize parameters influencing the synthesis of dispersed carbon nanoparticles (CNPs), a new class of sorbents, in order to obtain an excellent adsorbent for desulfurization of liquid fuel. The optimized dispersed CNPs, which are immiscible in liquid fuel, can effectively adsorb different benzothiophenic compounds. Equilibrium adsorption was achieved within 2 min for benzothiophene, dibenzothiophene, and 4,6-dimethyldibenzothiophene with removal efficiency values of 75 %, 83 %, and 52 %, respectively. The rate of desulfurization by the prepared CNPs in the present work is seven times higher than the previously reported CNPs. Optimized CNPs were characterized by different techniques. Finally, the effect of the mass of CNPs on the removal efficiency was studied as well.

Copper/zinc bimetal nanoparticles-dispersed carbon nanofibers: A novel potential antibiotic material

Copper (Cu) and zinc (Zn) nanoparticles (NPs) were asymmetrically distributed in carbon nanofibers (CNFs) grown on an activated carbon fiber (ACF) substrate by chemical vapor deposition (CVD). The CVD conditions were chosen such that the Cu NPs moved along with the CNFs during tip-growth, while the Zn NPs remained adhered at the ACF. The bimetal–ACF/CNF composite material was characterized by the metal NP release profiles, in-vitro hemolytic and antibacterial activities, and bacterial cellular disruption and adhesion assay. The synergetic effects of the bimetal NPs distributed in the ACFs/CNFs resulted from the relatively slower release of the Cu NPs located at the tip of the CNFs and faster release of the Zn NPs dispersed in the ACF. The Cu/Zn-grown ACFs/CNFs inhibited the growth of the Gram negative Escherichia coli, Gram positive Staphylococcus aureus, and Methicillin resistance Staphylococcus aureus bacterial strains, with superior efficiency (instant and prolonged inhibition) than the Cu or Zn single metal-grown ACFs/CNFs. The prepared bimetal–carbon composite material in this study has potential to be used in different biomedical applications such as wound healing and antibiotic wound dressing.

Fabrication of Ni nanoparticles-dispersed carbon micro-nanofibers as the electrodes of a microbial fuel cell for bio-energy production

A nickel (Ni) nanoparticles- (NPs) dispersed web of carbon micro-nanofibers (ACFs/CNFs) was fabricated as the electrode of a microbial fuel cell (MFC) for bio-energy production using Escherichia coli as a microbial catalyst. The multiscale web of ACFs/CNFs was prepared using chemical vapor deposition, with the Ni NPs as the catalyst and benzene as the carbon source to grow the CNFs on the ACF substrate. The Ni NPs attached at the tips of graphitic CNFs facilitated the transfer of E. coli-released electrons to the anode of MFCs. Linear sweep voltammetry was performed to determine power density and open circuit potential (OCP) of the prepared MFCs. The power density and OCP were experimentally measured as 710 ± 5 mV and 1145 ± 20 mW/m2, respectively, which were approximately 9 times greater than those of the ACF substrate-based MFCs. The transition metal-CNFs-based electrodes prepared in this study may be a potentially alternative to the expensive noble metals-based electrodes presently used in MFCs.

Preparation and characterization of SiO2/C nanocomposites by a combination of mechanochemical-assisted sol–gel and dry ball milling processes

A novel preparation route was developed for synthesizing SiO2/C nanocomposites through a mechanochemical-assisted sol–gel process combined with a high-energy dry ball milling process. The effect of process parameters, such as milling time, rotation speed and carbon content, on the structure and morphology of SiO2/C nanocomposites was investigated by X-ray diffraction, Fourier transform infrared spectroscopy, field-emission scanning electron microscopy and transmission electron microscopy with energy-dispersive spectroscopy. It was demonstrated from the physical characterization that the proposed preparation route might be an effective synthesis route for SiO2/C nanocomposites consisting of highly dispersed carbon nanoparticles on fine amorphous SiO2 particles. The electrochemical performance was characterized using Li|1M LiPF6 in EC:DMC=1:1| SiO2/C cells in the potential range from 0.01 to 3.0V versus Li/Li+. The SiO2/C nanocomposite prepared under optimized process conditions exhibited a highly stable reversible capacity of 663mAhg−1(872mAhg-SiO2−1) at a current density of 46mAg−1 after 30 cycles with no capacity fading.

Preparation of UC0.07−0.10N0.90−0.93 spheres for TRISO coated fuel particles

The US Department of Energy is considering a new nuclear fuel that would be less susceptible to ruptures during a loss-of-coolant accident. The fuel would consist of tristructural isotropic coated particles with dense uranium nitride (UN) kernels with diameters of 650 or 800μm. The objectives of this effort are to make uranium oxide microspheres with adequately dispersed carbon nanoparticles and to convert these microspheres into UN spheres, which could be then sintered into kernels. Recent improvements to the internal gelation process were successfully applied to the production of uranium gel spheres with different concentrations of carbon black. After the spheres were washed and dried, a simple two-step heat profile was used to produce porous microspheres with a chemical composition of UC0.07−0.10N0.90−0.93. The first step involved heating the microspheres to 2023K in a vacuum, and in the second step, the microspheres were held at 1873K for 6h in flowing nitrogen.

Selective Desulfurization of Model Diesel Fuel by Carbon Nanoparticles as Adsorbent

This work examines the effect of aromatic compounds (naphthalene and 1-methylnaphthalene) on the adsorption of sulfur thiophenic compounds (including benzothiophene, dibenzothiophene, and dimethyldibenzothiophene) from simulated diesel fuel by dispersed carbon nanoparticles (CNPs) in aqueous solution. To evaluate the equilibrium and kinetics of adsorptive desulfurization by synthesized CNPs, two model diesel fuels with 300 ppmw total concentration of sulfur compounds were used in a batch reactor at ambient conditions. The solid CNPs were characterized using FTIR, thermal analysis, elemental analysis, TEM, and surface pH. The equilibrium experimental data were fitted to Langmuir, Freundlich, and Langmuir–Freundlich models to estimate the adsorption parameters. Different equations were applied to fit the kinetics of adsorption and to determine its mechanism. The selectivity for benzothiophene (BT), dibenzothiophene (DBT), and dimethyl dibenzothiophene (DMDBT) adsorption was calculated with naphthalene as reference (NP). Both the adsorption capacity and the selectivity were in the order of BT > DBT > methyl NP ≈ DMDBT > NP. It was found that the rate of adsorption is high and aromatic compounds have no effect on the adsorption kinetics of thiophenic compounds. The results showed that the CNPs can act as a selective adsorbent for the removal of thiophenic carbons in competition with aromatics.