Graphite Nanoparticles Research Articles

Optical Microstructure, FESEM, Microtensile, and Microhardness Properties of LM 25-B4Cnp-Grnp Hybrid Composites Manufactured by Selective Laser Melting

The current investigation, nano-multi-powder particles, 5 and 10 wt.% boron carbide (B4C) and graphite (Gr) are utilized as a reinforcement, and aluminium LM 25 alloy is used as a matrix. These hybrid nanocomposites were fabricated by a novel additive manufacturing method—selective laser melting. The specimen was carried out in a cylindrical size having 2 circular slots of dimension 14 and length 50 mm. The diverse SLM specimens focused on tribological properties of impact, creep, tensile, and hardness were carried out for the three specimens with same weight percentage of nanoparticles. The consequence of the reinforcement has been performed through microtensile and microhardness tests. The microtensile and microhardness properties are evaluated by microtensile test machine and Vickers hardness tester, and the specimen has been prepared as per ASTM E8 and ASTM E18 standards. Microtensile strength and hardness were augmented by the addition of B4C and graphite nanoparticles. The tensile strength and hardness values are 668.93 MPa and 739.16 MPa, and 193VHN and 206.79VHN, respectively. The result of the microstructure study shows homogeneous dispersion of B4Cnp-Grnp in the matrix material of the LM25 alloy. The FESEM image results of the ruined surface illustrate the addition performance of ductile fracture, brittle fracture, and ploughing of reinforced material. The consequences of the research enhanced tensile and hardness properties of composite with reinforcement added.

Time-dependent oxidation of graphite and cobalt oxide nanoparticles as electrocatalysts for the oxygen evolution reaction

• Co 3 O 4 /G OX was synthesized via a facile hydrothermal method for the OER. • Co 3 O 4 /G OX-10 catalyst showed the lowest overpotential of 250 mV at 10 mA cm −2 . • The optimal catalyst exhibited higher specific activity and turnover frequency. • Demonstrated improved electrical conductivity and small charge transfer resistance. • The optimal catalyst Exhibited excellent stability and durability. Water splitting is a promising way of producing hydrogen, but a highly efficient and durable electrocatalyst to accelerate the oxygen evolution reaction (OER) is required. In this study, we report cobalt oxide (Co 3 O 4 ) and oxidized graphite (G OX ) synthesized by a simple hydrothermal method to prepare a catalyst (Co 3 O 4 /G OX ) for the OER. Time-dependent oxidation of graphite (G) and Co 3 O 4 nanoparticles was observed by physical and electrochemical studies. The optimal catalyst (Co 3 O 4 /G OX-10 ) demonstrated the best catalytic OER performance with the lowest overpotential of 250 mV to reach 10 mA cm −2 and a small Tafel slope of 67 mV dec -1 , which is substantially smaller than that of pristine Co 3 O 4 and Co 3 O 4 /G. An efficient synergistic effect between Co 3 O 4 and G OX in the composite catalyst was observed compared to the individual catalysts. The optimal catalyst exhibited high specific activity (1.543 mA cm −2 ) and turnover frequency (0.474 s −1 ) compared to the other catalysts in this study. The high catalytic performance of the catalyst is attributed to the presence of oxygen functional groups, which induced a high electrochemical surface area, additional active site exposure, fast electron transfer, and enhanced dispersion of the catalyst. Thus, the synthesized Co 3 O 4 /G OX-10 catalyst can replace noble metals as an efficient OER electrocatalyst.

Conductive Layers on a Shrinkable PET Film by Flexographic Printing.

In this study, the extremely important and difficult topic of flexographic printing on a heat-shrinkable substrate was taken up. Six commercially available, electrically conductive inks based on silver, copper and graphite nanoparticles were selected and tested upon their applicability for printing on the temperature-sensitive PET material. As a printing substrate, the one-direction heat-shrinkable PET film, with a maximum shrinkage of 78%, was selected. All of the examined inks were subjected to the printing process throughout three different anilox line screens. The tested inks, along with the electric paths printed with them, were subjected to various tests. The main parameters were evaluated, such as printability combined with the rheology tests and ink adhesion to the examined PET substrate together with the electrical conductivity before and after the shrinkage.

Surface microstructure evolution mechanism of WC-Co hard alloy treated by high current pulsed electron beam

The surface of WC-Co hard alloy was modified treatment by high current pulsed electron beam (HCPEB). The surface microstructure evolution mechanism of WC-Co hard alloy was characterized by XRD, SEM, EBSD, and TEM, respectively. The temperature distribution of WC-Co hard alloy during HCPEB treatment process was calculated and discussed. The results show that rapid melting and rapid solidification induced by HCPEB caused the phase transformation and the microstructure evolution on the surface of the hard alloy, and when irradiation times was 13th times, the microcracks and voids on the WC-Co hard alloy surface were gradually healed by remelting repeatedly, causing the formation of dense nanostructures. The microhardness of the modified specimen surface layer by 13th irradiation increased to 1159.0 HV, and the wear resistance increased to 1.72 times that of the matrix. The strength and wear resistance of the surface layer of the specimen were improved due to the refinement of WC grains, the forming of WC1-X nanophase, and the precipitation of nanographite particles. The microstructure evolution mechanism on the alloy surface after the modified treatment was proposed that a metastable equilibrium system was formed (WC + WC1-X + Co3W9C4+graphite phase).

Fabrication and Thermal Performance of 3D Copper-Mesh-Sintered Foam/Paraffin Phase Change Materials for Solar Thermal Energy Storage

Due to its large latent heat and high energy storage capacity, paraffin as one of the phase change materials (PCMs) has been widely applied in many energy-related applications in recent years. The current applications of paraffin, however, are limited by the low thermal conductivity and the leakage problem. To address these issues, we designed and fabricated form-stable composite PCMs by impregnating organic paraffin within graphite-coated copper foams. The graphite-coated copper foam was prepared by sintering multilayer copper meshes, and graphite nanoparticles were deposited on the surface of the porous copper foam. Graphite nanoparticles could directly absorb and convert solar energy into thermal energy, and the converted thermal energy was stored in the paraffin PCMs through phase change heat transfer. The graphite-coated copper foam not only effectively enhanced the thermal conductivity of paraffin PCMs, but also its porous structure and superhydrophobic surface prevented the paraffin leakage during the charging process. The experimental results showed that the composite PCMs had a thermal conductivity of 2.97 W/(m·K), and no leakage occurred during the charging and discharging process. Finally, we demonstrated the composite PCMs can be readily integrated with solar thermoelectric systems to serve as the energy sources for generating electricity by using abundant clean solar-thermal energy.

Impact of N2 admixture on the synthesis of graphitic carbon nanoparticles using atmospheric-pressure microwave plasma

Atmospheric-pressure microwave plasma was utilized for catalyst-free gas-phase synthesis of graphitic carbon nanoparticles by adding CH4 to a mixture of N2 and He. The impact of N2 on the formation of the graphitic carbon nanoparticles was analyzed by increasing the N2 flow rate from 0 to 20 slpm and decreasing the He flow rate from 40 to 20 slpm simultaneously. The addition of N2 altered the morphology of the carbon nanoparticles to obtain flatter and larger shapes. Furthermore, carbon nanoparticles synthesized with N2 possessed more graphitic structures with higher C/O ratios and larger crystallite sizes than those synthesized without N2. The analysis of gas compositions at thermodynamic equilibrium states demonstrated that CN and HCN were the dominant precursor species when N2 was added. The presence of N atoms or N-containing species seem to have a synergistic effect combined with H atoms on the formation of the graphitic carbon nanoparticles.

A template-method synthesis of mesoporous-MgO/expanded graphite for enhancing thermal properties of methyl palmitate-lauric acid phase change materials

Relatively weak thermal conductivity and antileakage performance of phase change materials (PCMs) limit their applications. The present work focuses on the development of a novel composite PCM (MP-LA/MgO/EG) based on the dispersion of expanded graphite (EG) and magnesium oxide (MgO) nanoparticles in a binary mixture of methyl palmitate-lauric acid (MP-LA). MgO/EG, a new supporting material, is assembled using expanded graphite and specially shaped MgO prepared with the surfactant-assisted high-temperature thermal decomposition method. In addition to maintaining the porous structure of EG and preventing the leakage of MP-LA, MgO/EG reduces the interface thermal resistance between the matrix and the PCM molecules because MgO maximizes heat conduction. The thermal conductivity of the proposed material (4.568 W/m/K) is 8.16 times higher than that of MP-LA, and its faster heat transfer rate is reflected directly in the infrared images. The enthalpy of MP-LA/MgO/EG-9 floats in a narrow range with the value of 1.88% during the process of heating-cooling cycles 100 times. The results reported herein can serve as a reference for the functional design of PCM supporting carriers that form good thermal conducting networks and provide the form-stable effect.

Graphitic carbon-wrapped iron nanoparticles derived from a melamine-modified metal-organic framework as efficient Friedel-Crafts acylation catalysts

Developing efficient heterogeneous catalysts for Friedel-Crafts acylation (FCA) reactions is highly attractive for its wide application in green synthesis and biomass conversion. Herein, a series of graphitic carbon-wrapped iron nanoparticles (Fe/C-x, x refers to the heat temperature ranged from 500 to 800 °C) were prepared through pyrolysis of a metal-organic framework (MOF) precursor of Fe-TPA-Mel, synthesized from iron salt, terephthalic acid (TPA) and melamine (Mel). The resultant Fe/C-600 catalyst exhibited excellent catalytic activity for the acylation of aromatic compounds with acyl chlorides, and better recyclability than the reference catalyst of Fe/C-600-ref derived from the Fe-TPA precursor. Various characterization results demonstrated that introducing melamine in the MOF precursor is beneficial for the formation of graphitic carbon-wrapped Fe nanoparticles at relatively low pyrolysis temperature, although the N species existed in the precursor of Fe-TPA-Mel could be nearly completed removed during the pyrolysis process. The relatively uniform graphitic carbon shell could provide an effective protection for the inside active iron species, finally resulting in the generation of stable and easily recycled heterogeneous FCA catalysts.

THz Radiation Generation Through Graphite Nanoparticles Having Two Different Shapes and Orientations of Basal Planes

Graphite nanoparticles (NPs) in two distinct geometries, i.e., cylindrical and spherical, having two different configurations of their basal planes with respect to the electric field of the laser beam are considered for the terahertz radiation generation with the help of the beating process of two coshyperbolic lasers having frequencies <inline-formula> <tex-math notation="LaTeX">$\omega _{1}$ </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">$\omega _{2}$ </tex-math></inline-formula>. Through analytical treatment, we show that a nonlinear ponderomotive force (&#x007E;0.47 dyne) that leads to nonlinear oscillating current is responsible for the radiation generation, when there is a matching of surface plasmon frequency of NPs (longitudinal surface plasmon resonance or transverse surface plasmon resonance) and beating frequency of the lasers (<inline-formula> <tex-math notation="LaTeX">$\omega =\omega _{1}- \omega _{2}$ </tex-math></inline-formula>). A substantial difference of the order of 10³ in the electric field of radiation is seen in the two configurations of NPs, i.e., when their basal planes are parallel or perpendicular to the field of the incident beams. This study also shows that the radiation field can be controlled by changing the geometry of the NPs, and the conversion efficiency is of the order of <inline-formula> <tex-math notation="LaTeX">${10}^{-4}$ </tex-math></inline-formula> in the case of the combined system of cylindrical and spherical NPs.

Thermal conductivity enhancement of shape-stabilized phase change nanocomposites via synergistic effects of electrospun carbon nanofiber and reduced graphite oxide nanoparticles

Recently, engineers and researchers have shown great interest in thermal energy storage (TES) through phase change materials (PCMs). This work designed a polyethylene glycol (PEG) / reduced graphite oxide nanoparticle (rGONP) incorporated in carbon nanofiber (CNF) shape-stabilized phase change nanocomposite (SSPCN) with different amounts of rGONP in nanofibers via an electrospinning process. PEG as PCM was absorbed in and/or supported by overlaid nanofibrous mats (e.g., CNFs, 90CNF + 10rGONP, and 50CNF + 50rGONP); then explored for thermal energy storage and retrieval. The rGONP impact on structural morphologies and thermal energy storage of SSPCNs was determined by FTIR, Raman, XRD, FESEM, TGA, and DSC analyses. According to the results, SSPCNs with and without rGONP loadings had suitable phase transition temperatures with the latent heat ranging from approximately 55.1 to 84.3 J g−1. Furthermore, the thermal conductivity of PCM was synergistically enhanced by CNF and rGONP; this was followed by a gradual increase in the former with the rGONP content. Due to rapid thermal response, the developed SSPCNs demonstrated excellent hi-tech applications in precise temperature control and fast temperature regulation conditions.

The rational design of a graphitic carbon nitride-based dual S-scheme heterojunction with energy storage ability as a day/night photocatalyst for formic acid dehydrogenation

Photocatalytic formic acid dehydrogenation (FAD) has been regarded as one of the most promising methods of producing H2 in a sustainable manner. In the photocatalytic FAD reaction, photogenerated holes play an important role in the reaction mechanism and thus in the efficiency of photocatalysts. However, the design of photocatalytic systems capable of generating high hole potential without compromising the reducing ability of the photocatalyst is extremely rare for the FAD reaction. In this respect, we report herein a novel and highly efficient heterojunction photocatalyst composed of 2D graphitic carbon nitride, 2D MnO2, 1D MnOOH, and 0D PdAg alloy nanoparticles, denoted as GCN/MnO2/MnOOH-PdAg, that can create high reduction and oxidation potentials via a dual S-scheme heterojunction. The photocatalysts exhibited a superb photocatalytic activity in the FAD with a record turnover frequency (TOF) of 3919 h−1 under visible light irradiation, which was 6-, 5.2- and 24-times greater than those of GCN-PdAg, GCN/MnO2-PdAg, and MnO2/MnOOH-PdAg heterojunctions, respectively. The structure and dual S-scheme mechanism of the photocatalyst have been clearly demonstrated by extensive instrumental analysis, radical trapping tests, and scavenger experiments. More importantly, it was discovered that the presented photocatalyst continued to function with comparable activity in dark for a prolonged time using the same photocatalytic mechanism. The activity of the photocatalyst in dark was attributed to the utilization of electrons stored on Mn2O3, which was detected as a 4–5 nm thick layer on the surface of MnOOH nanorods. This study, in addition to being the first example of both a “day/night photocatalyst” for FAD with an S-scheme mechanism, also demonstrates for the first time the boosting of FAD via a dual S-scheme heterojunction photocatalyst.

Energy, exergy, sustainability and economic analysis of waste tire pyrolysis oil blends with different nanoparticle additives in spark ignition engine

Fossil fuels are the primary source of energy for most industries worldwide. However, its resources are finite and declining day by day, and toxic gases are released due to their consumption which causes global warming and problems with the health of the living. Therefore, any alternatives to fossil fuels or any additives added to the fuel needed to be found to minimize fuel consumption and the emission of harmful gases. In this study, a spark-ignition engine fuelled with blends of petrol with different concentrations of graphite nanoparticles, Fe2O3 nanoparticles, and tire pyrolysis oil (TPO) were used to conduct energy, exergy, economic, and sustainability analyses, and the obtained results were compared with neat petrol. The blends of petrol with 40 mg/L, 80 mg/L, and 120 mg/L of graphite nanoparticles & Fe2O3 nanoparticles, as well as 5% & 10% TPO, were used in a single-cylinder, four-stroke, air-cooled SI engine in this study. The experiments were conducted on various engine loads of 2 Nm to 10 Nm with an increment of 2 Nm at a constant speed of 3500 rpm. The maximum exergy and energy efficiencies were obtained 23.05% and 21.94% at a load of 8 Nm when the testengine fired with the P120FO blend, respectively. A maximum sustainability index of 1.3 for the P120FO blend was obtained. A minimum exhaust energy rate of 0.03241 kW was obtained for P120FO. A minimum exhaust exergy rate of 0.005849 kW was obtained for P90T10. Best results in energy efficiency, exergy efficiency, sustainability index, and economic analysis were obtained for the P120FO blend compared to neat petrol. Finally, it was concluded that the addition of nanoparticles in fossil fuel increases the engine's efficiency, decreases fuel consumption, and reduces the emission of harmful gases.

Dynamic dielectric properties of isotactic polypropylene-g-maleic anhydride crosslinked by capped-end polyether diamine and filled with native or functionalized nano-graphite particles

Dynamic dielectric properties of an isotactic polypropylene matrix grafted with maleic anhydride (CA 100) and then crosslinked by polyether amine molecules and reinforced with different weight percentages of graphite nanoplatelets (GNPs), KNG180, were studied for the first time and compared to those obtained by DMA (Dynamic Mechanical Analysis). The main objective of this work was to investigate the reinforcement effect of GNPs focusing on the GNPs/matrix interfacial adhesion using dynamic dielectric relaxation spectroscopy in the frequency range from 0.1 Hz to 1 MHz and temperature range from 20 to 140 °C. The obtained interfacial polarization increments \({\Delta \varepsilon }_{\mathrm{MWS}}\) from MWS (Maxwell Wagners Sillars) relaxation showed a threshold value of 3% in weight of KNG180. This analysis suggests that interfacial compatibility between matrix and fillers in the case of nanocomposite KNG180 3 wt% is higher than those of other nanocomposites. A new plasma treatment was used to modify graphite nano-fillers to produce different types of nanocomposites. The 5 wt% plasma treated graphite nanocomposite shows a good dispersion of the nano-fillers but also a high value of \({\Delta \varepsilon }_{\mathrm{MWS}}\), which is an indication of high graphite/graphite interaction. This evolution could show that this material can be close to the formation of an electrical percolation network.

Laser intensity profile based terahertz field enhancement from a mixture of nano-particles embedded in a gas.

Nano-particle embedded system plays an importance in developing of future terahertz (THz) radiation source for real-world applications. The laser interactions with nanoparticle embedded system can produce a wide range of THz radiation due to plasma oscillations excitation. We investigate THz field generation from the laser-beat wave interaction with a mixture of spherical and cylindrical graphite nanoparticles in argon gas. Different laser intensity distributions such as Gaussian, cosh-Gaussian, flat-top and ring shape laser pulses have been studied in this work. The relevant plasmon resonance conditions with appropriate symmetry of spherical nanoparticles and cylindrical nanoparticles are discussed. THz field is enhanced upto the order of 10^{2} when the laser intensity redistributes along the polarization direction for a ring shape field envelope.

Structure and morphology of graphite nanoparticles treated by fiber laser irradiation

The graphite nanoparticles (GNPs) were prepared on the surface of monocrystalline Si by laser irradiation under different laser energy densities (3.3–8.33 kJ/cm2). The effects of laser energy density on structure and surface morphology were systematically investigated. The results show that the morphology of GNPs remained polycrystalline structure under laser irradiation with an energy density of 2.22 kJ/cm2. When the laser energy density was 2.78 kJ/cm2, the GNPs can induce the preset GNPs to transform into amorphous graphite nanofibers. The GNPs under the laser density of 3.33 kJ/cm2 showed a more amorphous structure. With the further increase of the laser energy density to 5.55 kJ/cm2, the main phase composition turned to SiC and Si.

Nanostructured P-doped activated carbon with improved mesoporous texture derived from biomass for enhanced adsorption of industrial cationic dye contaminants

Developing of high-performance carbonaceous materials from biomass is a significant contemporary research subject to meet the increasing demand for functional adsorbents with low price, high available and sustainability for adsorptive removal processes of industrial pollutants. The present work investigates formation of nanostructured surface modified P-doped activated carbon (ACP) materials via thermochemical activation of orange peel (OP) biomass residual materials, by phosphoric acid, H3PO4. Different impregnation ratios of phosphoric acid to OP (w/w) were investigated at different activation temperatures (400–800 °C). The formed ACP materials were characterized by TGA−DTA, FTIR−ATR, Raman spectroscopy, XRD, N2 gas adsorption/desorption, HR−TEM microscopy, EDX and elemental surface mapping. The results indicated that ACP materials were structured in the form of plate-like nanoparticles of amorphous graphite that composed of few graphene layers. The ACP materials exhibited high surface area (up to 1700 m2/g) with high contribution from mesoporosity (up to 94%) of slit-like pore shape. The point of zero charge was found at pH of 6.3, which permits application at neutral adsorption conditions. The formed ACP adsorbents exhibited distinguished adsorption capacities, qads, for methylene blue (MB) with successful recyclability. The adsorption capacities were enhanced (up to qads = 452 mg/g) for the materials formed at high acid impregnation ration and activated at high temperatures. The adsorption process of MB was spontaneous, fits with the Langmuir adsorption isotherm and pseudo-second-order kinetic. The high adsorption capacities for the ACP adsorbents were correlated with their micro/nano-structures, which were dominated by nano plate−like amorphous graphite particles composed of few graphene−like layers.

Electrical and electromagnetic interference shielding properties of GNP-NiFe hybrid composite with segregate structure of conductive networks

Conductive polymer composites are widely used for electromagnetic radiation protection. Several strategies can be employed for creating shield materials with enhanced efficiency: the use of a hybrid filler that contains nanoparticles of different types, specific structural design, and methods for decreasing the percolation threshold. We present the study of segregated polymer composites (SPCs) with ultrahigh molecular weight polyethylene (UHMWPE) matrix and hybrid fillers of NiFe-decorated graphite nanoparticles (GNPs). The microstructure, electrical percolation behavior, and electromagnetic shielding efficiency of the developed SPCs as a function of conductive filler content are determined. The combination of the advantages of the segregated structure with a synergistic effect of a hybrid filler in (GNP-NiFe)/UHMWPE allows decreasing the percolation threshold to 0.45 vol. %. The enhanced shielding efficiency of 37 dB in the frequency range of 26–37.5 GHz is achieved at the filler content of 3.4 vol. % in 1 mm thick composite samples. The dominant shielding characteristic of absorption renders hybrid composites with a segregated structure promising materials.

Synthesis of hybrid nanocomposites by sol-gel method and their characterizations

In this work, we report the synthesis of different hybrid nanocomposites by sol-gel method. Therefore, we used picric acid as a catalyst to incorporate the nanopowder oxides of nickel (NiO), copper (CuO) and manganese (MnO) in the porous carbon matrix based on pyrogallol and formaldehyde (PF). After a drying and heat treatment for two hours at 650 °C pyrolysis temperature, the obtained materials have been characterized by different structural and electrical techniques. The X-ray diffraction (XRD) spectra show that the incorporation of inorganic nanoparticles improved the crystallization of different nanocomposites with the existance of a graphite phase. The transmission electron microscopy (TEM) images reveal that the graphite nanoparticles size depends to the incorporated inorganic oxide. From the electrical studies, we notice that electrical conduction is linked to the presence of graphite nanoparticles. The variation of the electrical conductivity and the relaxation time with the measurement temperature, ranging between 80 and 300 K, explain the effect of the hopping conduction mechanism in these nanocomposites.

Construction of SnO2/g-C3N4 an effective nanocomposite for photocatalytic degradation of amoxicillin and pharmaceutical effluent

The current study mainly focused on the fabrication of 2D graphitic carbon nitride-supported tin oxide nanoparticles (SnO2/g-C3N4) for the effective degradation of Amoxicillin (AMX). Tin oxide (SnO2) NPs were prepared by green and easy modification technique, and then it is decorated over g-C3N4 nanosheets. The structural morphology and surface composition of the synthesized SnO2/g-C3N4 nanocomposite were fully analysed by UV–Vis, XRD, XPS, and HR-SEM with EDAX, FT-IR, and BET analysis. The (HR-TEM) microscopy, the size of SnO2 NPs which as a diameter is about 6.2 nm. The Raman analysis revealed that the SnO2/g-C3N4 composite had a moderate graphitic structure, with a measured ID/Ig value of 0.79. The degradation efficiency of antibiotic pollutant AMX and pharma effluent treatment was monitored by UV spectroscopy. The optical band gap of SnO2 (2.9 eV) and g-C3N4 (2.8 eV) photocatalyst was measured by Tauc plots. To investigate the mechanism through the photodegradation efficiency of the catalyst was analysed by using different Scavenger EDTA-2Na holes (h+) has a greater contribution towards the degradation process. Under visible irradiation, SnO2/g-C3N4 nanocomposite has exhibited an excellent degradation performance of 92.1% against AMX and 90.8% for pharmaceutical effluent in 80 min.

Composites of Co-Doped Graphitic C3N4 Nanosheets and TiO2 Nanoparticles for Electrorheological Fluid Applications

Composites of Co-Doped Graphitic C₃N₄ Nanosheets and TiO₂ Nanoparticles for Electrorheological Fluid Applications