Ball-milled Graphite Research Articles

Microfluidic Shape Analysis of Non-spherical Graphite for Li-Ion Batteries via Viscoelastic Particle Focusing.

The size and shape of graphite, which is a popular active anode material for lithium-ion batteries (LIBs), significantly affect the electrochemical performance of LIBs and the rheological properties of the electrode slurries used in battery manufacturing. However, the accurate characterization of its size and shape remains challenging. In this study, the edge plane of graphite in a cross-slot microchannel via viscoelastic particle focusing is characterized. It is reported that the graphite particles are aligned in a direction that shows the edge plane by a planar extensional flow field at the stagnation point of the cross-slot region. Accurate quantification of the edge size and shape for both spheroidized natural and ball-milled graphite is achieved when aligned in this manner. Ball-milled graphite has a smaller circularity and higher aspect ratio than natural graphite, indicating a more plate-like shape. The effects of these differences in graphite shape and size on the rheological properties of the electrode slurry, the structure of the coated electrodes, and electrochemical performance are investigated. This method can contribute to the quality control of graphite for the mass production of LIBs and enhance the electrochemical performance of LIBs.

One-Pot Direct Mechanochemical Silicon Replacement of Sodium Fluorosilicate into Sodium Fluorozirconate and Functionalization of Graphite for Enhanced Sodium-Ion Storage.

Efficient sodium ion storage in graphite is as yet unattainable, because of the thermodynamic instability of sodium ion intercalates-graphite compounds. In this work, sodium fluorozirconate (Na3ZrF7, SFZ) functionalized graphite (SFZ-G) is designed and prepared by the in situ mechanochemical silicon (Si) replacement of sodium fluorosilicate (Na2SiF6, SFS) and functionalization of graphite at the same time. During the mechanochemical process, the atomic Si in SFS is directly replaced by atomic zirconium (Zr) from the zirconium oxide (ZrO2) balls and container in the presence of graphite, forming SFZ-G. The resulting SFZ-G, working as an anode material for sodium ion storage, shows a significantly enhanced capacity of 418.7 mAh g-1 at 0.1 C-rate, compared to pristine graphite (35 mAh g-1) and simply ball-milled graphite (BM-G, 200 mAh g-1). In addition, the SFZ-G exhibits stable sodium-ion storage performance with 86% of its initial capacity retention after 1000 cycles at 2.0 C-rate.

Synthesis of graphene/Ru/NiO composites as highly active oxygen evolution reaction electrocatalysts

Graphene nanoplates which are decorated uniformly with ruthenium (Ru) and nickel oxide (NiO) nanoparticles, are fabricated via ball milling of graphite, triphenylphosphine ruthenium chlorides and nickel chlorides. Electrochemical measurement results demonstrate that the resultant graphene/Ru/NiO composites deliver a lower overpotential of 240 mV at current density of 10 mA cm−2 and better durability for oxygen evolution reaction (OER) than the state-of-the-art iridium oxide catalysts. The superior OER performances of the graphene/Ru/NiO composites are attributed to collective contributions of Ru and NiO.

Milled graphitic nanoparticle toughened epoxy composites via increased resistance to in-plane crack propagation

Fascinating features of 2D-based carbon materials like graphene have drawn increasing attention to fulfill the desire to enhance the fracture toughness of epoxy composites. However, challenges remain to improve their dispersibility in polymers and increase interaction ability. Thus, work is needed to synthesize alternative cost-effective 2D carbon nanofillers capable of delivering consistent performance as a reinforcer to monitor the fracture toughness of the epoxy composites. The present study demonstrates transforming graphite to ball-milled graphite (BMG) via an effective high-energy wet ball milling process. Herein a noteworthy size reduction is achieved for the BMG ranging from ∼217 to 227 nm. Microscopic investigation spotted an exfoliated 3D networked graphite nanosheet with nanopores. These BMGs were functionalized to attach amine-based silane moieties and were incorporated into the epoxy network. Consequently, even at higher loading levels, they showed their astonishing capability to enhance the crack far field resistance of nanocomposite resulting in significantly improved fracture toughness and energy to ∼2.31 MPa m1/2 and ∼11.30 kJ/m2, respectively. Improvement is ascribed to the better dispersing ability of BMG, which provides a consistent strong interfacial interaction with the epoxy network to modulate material resistance to fracture. Such environmentally friendly nanofillers must be industrially acceptable for synthesizing durable epoxy nanocomposite systems and can be utilized to prepare structural composites.

Testing carbon structures for metal-free catalytic/photocatalytic ozonation to remove disinfection by-product formation potential

Different graphitic carbon structures were prepared and tested for catalytic and photocatalytic ozonation of the precursors of chlorination disinfection by-products to remove their disinfection formation potential (DBPFP). Commercial graphite was submitted to ball milling and two chemical treatments with ammonium nitrate or potassium oxalate to increase its surface area. Additionally, ozonation in gas phase and liquid phase were used to generate surface oxygen groups in these materials and in commercial graphene. All the carbon samples were tested and compared with commercial graphene oxide in the removal of humic acid solutions. The highest catalytic activity during the catalytic/photocatalytic ozonation of humic acid was observed for commercial graphene, ozonated graphene and for graphene oxide; however, this did not result in high DBPFP removal and the instability of the materials was demonstrated. With a moderate catalytic activity but better stability, ball-milled graphite ozonated in liquid phase, was selected for photocatalytic ozonation of real surface water leading to a high DBPFP removal at the conditions tested (88 % 5-HAAs (haloacetic acids), 70 % 4-THMs (trihalomethanes), 70 % AOX (adsorbable organic halides); conditions: semi-batch experiments; 0.5 L volume; 5 mg L−1 O3; Qg = 10 L h−1; DOC0 = 5 mg L−1; pH = 7.8; 180 min under simulated solar radiation with average irradiance 580 W m−2).

Sustainable mining of natural vein graphite via acid-extraction from waste attached to rock pieces of vein banks

A procedure based on acid extraction using a mixture of conc. sulfuric and nitric acids (8:1) to recover graphite attached to rock pieces of the vein contact zones of graphite mines, is developed as a sustainable mining practice. When the extracted graphite is heated at 600 °C for 15 min, it is converted to a highly expanded form resembling worm-like structures. The unique properties of this graphite and expanded graphite are presented by characterizing using FT-IR, Raman, SEM–EDX and XRD. This expanded graphite has the oil absorption capacity of 120 g of oil per 1 g of expanded graphite, making it the material so far known to have the highest oil absorption capacity. For comparison purpose, properties of ball-milled graphite powder which was obtained from the middle of the vein is prepared and characterized. However, the ball-milled graphite does not expand upon heat-treatment at 600 °C for 15 min. The acid-extracted graphite (AEG) has lower purity than that of ball-milled graphite (BMG), but heat-treatment increases the purity of the AEG while BMG shows opposite results. The purity of AEG has increased considerably upon heat-treatment by lowering the O wt% (weight percentage) by 6.07% to half of its original value while increasing C wt% by 8.05%. On the contrary, the C wt% of BMG has decreased by 3.71% and O wt% increased by 3.84%. The increase of purity upon heat treatment of AEG is due to the removal of some carbon and sulfur impurities as their volatile oxides. The ball-milled graphite absorbs carbon dioxide from the atmosphere when heat-treated at 600 °C. As such, the ball-milled graphite powder can be used to extract carbon dioxide from the atmosphere. The crystallite size of AEG is 1.25 times larger than that of BMG and it has been increased by 8 and 2.9 times, respectively, upon heat-treatment at 600 °C for 15 min. This is a clear evidence to expanded nature of AEG compared to BMG.

Epoxy composites integrated with functionalized wet‐milled graphitic nanoparticles: Featuring enhanced mechanical performance and in‐plane fracture resistance

AbstractComposites made of epoxy‐based systems are popular in many engineering applications because of their enhanced mechanical performance, fatigue properties, and other physical and thermal properties, but their low fracture toughness can limit their usefulness in high‐performance structural applications. This study aims to enhance the fracture properties of epoxy‐based composites by adding cost‐effective ball‐milled graphitic nanoparticles. Herein, dry ball milling for 15 and 48 h is done to produce ball‐milled graphite (BMG) nanoparticles. A significant reduction in particle size is achieved after 15 h of dry milling. Interestingly, a similar reduction in particle size is achieved for BMG (~258 nm) when wet ball milling for 3 h is performed. These BMGs were silanized (SBMG@3) and incorporated into the epoxy network. We found even at a higher loading level of SBMG@3, the resulting nanocomposites exhibited a significant improvement in fracture toughness (~2.47 MPa m1/2) and energy (~1.55 kJ/m2). This improvement was attributed to the upliftment of the in‐plane crack propagation resistance of the nanocomposites primarily offered by SBMG@3 due to coagulated interfacial interaction with the epoxy network that effectively hindered the propagation of the crack by providing numerous sites for energy dissipation, leading to improved fracture toughness. Our results demonstrate that SBMG@3 has great potential for improving the fracture toughness and energy of epoxy‐based composites, making them suitable for various industrial applications.Highlights Synthesized cost‐effective 2D carbon nanofillers via high‐energy ball milling. To overcome the re‐agglomeration effect wet ball milling is performed. Transformation of natural graphite to BMG with sizes of ~258 nm. KIC and GIC improve to ~2.47 MPa m1/2 and 1.55 kJ/m2, respectively, for ECSB1. FS and FM of the epoxy nanocomposites enhanced by ~43.69% and ~51.64%.

Effect of ball milling and subsequent size reduction of graphite flakes on the surface mechanical properties of graphitized Al-1100 alloy

Current study explains about ball milling and subsequent mechanical insertion of graphite particles into aluminium (Al-1100) surface for forming composites on surface through an electrical resistance heat supported pressing procedure. Ball milling of as-received 60 mesh graphite particles was carried out which successfully reduced the particle size. After that surface of the aluminium is coated with ball-milled graphite by solution casting. For impregnation, the interface of graphite/aluminium is locally heated by the assistance of an electrical resistance heating followed by mechanical pushing. Heat generation and thus level of aluminium surface softening can be structured by process factors like current and heating time. SEM, TEM, Raman spectroscopy and XRD were employed for microstructural characterization. Successful impregnation and agglomeration of graphite particles inside aluminium matrix is revealed from microstructural characterization. Impregnated graphite particles when characterized with Raman spectroscopy shows band shifting and increased intensity ratio (ID/IG). Presence of intermetallic compound (Al4C3) was not detected from the XRD and TEM study. Surface and subsurface mechanical characterization was carried out nanoindentation and microhardness respectively. The modified surface while shows an improvement of more than 120 % in mechanical properties, 130 % improvement is also observed in Young’s modulus. The projected method can be utilized as surface modification technique in solid-state by fabricating surface composites fabricated through mechanical insertion of particulate reinforcement at sub-melting temperatures of substrate and under open producing environment.

Directly transforming graphite into iron single atom catalyst for the acidic oxygen reduction reaction

Platinum group metal (PGM)-free single atom catalysts (SACs) are highly desired to accelerate the sluggish oxygen reduction reaction (ORR) in acidic media, which has a critical role in renewable energy technologies. Herein, we report the direct transformation of commercial graphite into iron (Fe) single atom anchored graphitic flake via a combination of mechanochemical and thermochemical synthesis. By ball milling graphite with zirconium dioxide balls and capsule in the presence of dry ice, the graphite was mechanochemically functionalized and exfoliated into carboxylated graphitic flake (CGF). Subsequent heat-treatment of CGF with nitrogen containing additives formed nitrogenated graphitic flake (NGF) incorporated with Fe single atoms (Fe1NGF). Importantly, the existing Fe impurity in the pristine graphite was converted into value-added product without adding Fe sources. With an ultralow Fe content (0.4 wt%), the as-prepared Fe1NGF exhibited an acidic ORR performance comparable to Pt/C, including ultrahigh mass activity, surpassing the other reported outstanding Fe-based SACs.

Nitrogen doped carbonaceous materials as platinum free cathode electrocatalysts for oxygen reduction reaction (ORR)

Comparison of physicochemical properties and electrocatalytic behavior of different N-doped carbonaceous materials as potential catalysts for oxygen reduction reaction (ORR) was attended. Ball-milling of graphite with melamine and solvothermal treatment of graphite oxide, graphene nanoplatelets (GNP) with ammonia were used as preparation methods. Elemental analysis and N2 physisorption measurements revealed the synthesis of N-doped materials with strongly different morphological parameters. Contact angle measurements proved that all three samples had good wettability properties. According to analysis of XRD data and Raman spectra a higher nitrogen concentration corresponded to a smaller size of crystallites of the N-doped carbonaceous material. Surface total N content determined by XPS and bulk N content assessed by elemental analysis were close, indicating homogenous inclusion of N in all samples. Rotating disc electrode tests showed that these N-doped materials weremuch less active in acidic medium than in an alkaline environment. Although the presence of in-plane N species is regarded to be advantageous for the ORR activity, no particular correlation was found in these systems with any type of N species. According to Koutecky–Levich analysis, both the N-containing carbonaceous materials and the reference Pt/C catalyst displayed a typical one-step, four-electron ORR route. Both ball-milled sample with high N-content but with low SSA and solvothermally synthesized N-GNP with high SSA but low N content showed significant ORR activity. It could be concluded that beside the total N content other parameters such as SSA, pore structure, structural defects, wettability were also essential for achieving high ORR activity.

Evolution of local atomic arrangements in ball-milled graphite

Evolution of local atomic arrangements in ball-milled graphite

Carboxylated graphene oxide nanosheets as efficient electrodes for high-performance supercapacitors.

In the presence of dry ice, a series of graphitic materials with carboxylated edges (ECGs) were synthesized by ball milling graphite for varied times (24, 36, and 46 h). The influence of carboxylation on the physiochemical characteristics and electrochemical performance as effective electrodes for supercapacitors were assessed and compared with pure graphite. Several characterization techniques were employed to investigate into the morphology, texture, microstructure, and modification of the materials. Due to its interconnected micro-mesoporous carbon network, which is vital for fast charge-discharge at high current densities, storing static charges, facilitating electrolyte transport and diffusion, and having excellent rate performance, the ECG-46 electrode among the investigated samples achieved the highest specific capacitance of 223 F g−1 at 0.25 A g−1 current density and an outstanding cycle stability, with capacitance retention of 90.8% for up to 10,000 cycles. Furthermore, the symmetric supercapacitor device based on the ECG-46 showed a high energy density of 19.20 W h kg−1 at 450.00 W kg−1 power density. With these unique features, ball milling of graphitic material in dry ice represents a promising approach to realize porous graphitic material with oxygen functionalities as active electrodes.

Production of functionalized graphitic carbon materials via solvent-free mechanochemical method for supercapacitors and water treatment

A facile and solvent-free mechanochemical method was developed here for the production of large-surface-area functional graphitized carbon materials (GCMs) with sp-hybridized carbon atoms, rich porosity, interlayered architecture by ball milling graphite and CaC2 at room temperature. The resultant GCM can be used as a supercapacitor electrode with capacitance of 238.4 F·g−1 at 0.2 A·g−1 in aqueous KOH solution and an excellent sorbent for heavy metal removal with adsorption of 463 and 1700 mg-Hg·g−1, respectively, at Ce = 9.2 and 230 μg. g−1. Its high capacitance and exceptional adsorbance may be ascribed to the well-developed pore volume (0.55 cm3·g−1), high specific area (~597 m2·g−1), ample alkyne groups, Lewis soft basicity of alkynyl groups and graphite nanosheets, as well as their synergistic interaction within confined space. The sp-hybrid carbon atoms are derived from the alkynyl carbon in calcium carbide, which endows GCM unique porosity and electron/ion transport properties. In view of its excellent electrochemical performance and high adsorption capacities for Hg(II), GCM is of potential application in energy storage and water treatment.

High-yield Production of Amorphous Carbon via Ball Milling of Graphite and Prediction of Its Crystallite Size through ANN

One of the main methods for the synthesis of amorphous and nanostructured carbon is the mechanical milling of graphite. However, calculation and anticipation of the amorphous phase during the mechanical milling of graphite still is a major challenge due to a lot of important parameters. The main aim of this study is to mass-produce amorphous carbon and predict the crystallite size of graphite. For this purpose, ball-milling of graphite powder was carried out at different times of milling. Then, the destruction of crystal structure and changes in phases were studied by XRD, TEM, AFM, SEM, and Zeta Seizer. The results of theMAUD analysis showed that 91% and 93% of the unmilled graphite were converted to amorphous carbon at 250 and 330 hours of ball-milling, respectively. In order to predict the crystallite size of carbon during the high energy ball-milling, the effective variables in the ball-milling process along with the initial crystallite size of carbon were determined as the input of the artificial neural network (ANN). Moreover, the final crystallite size of carbon was considered as the output of the network. The designed network with a root mean square error (RMSE) of 4% was able to predict the crystallite size of carbon during the process. Finally, by comparing the experimental results and the designed model, it was shown that the predicted results were very close to the experimental outcomes. Accordingly, the presented model can be used for predicting the crystallite size of carbon during the mechanical milling of graphite.

The influence of mechanochemical treatment in hexane on dispersibility and floatability of graphite flakes with enhanced water evaporation performance

The dispersibility and floatability of graphitic carbon materials in water are two contradictory properties with significant importance in a wide variety of applications. Here, we investigate the effect of ball-milling (BM) in the presence of NaCl and n-hexane on the dispersibility and floatability of graphite flakes in water. The exfoliated carbons are characterized by different techniques including the ultraviolet-visible (UV-Vis) absorption and Fourier-transform infrared spectroscopy (FTIR), as well as Raman and X-ray diffraction (XRD) analysis. The increase in the defect density of carbons caused by the BM process, and the presence of n-hexane influence the behavior of exfoliated flakes in water. While the BM at shorter time periods enhances the dispersion performance, the ball-milled graphite is found to be readily floatable on the surface of water at longer BM durations in the presence of sufficiently high amounts of n-hexane used during the BM process. The mechanochemical mechanism involved in enhancing the dispersibility and floatability of graphitic carbon materials is discussed. Furthermore, the enhanced water evaporation performance of the water-floatable carbon prepared by the mechanochemical approach is demonstrated. This article suggests a facile and potentially scalable approach for the preparation of floatable graphene flakes with enhanced performance as free-standing media for light-induced water evaporation applications.

Acacia mangium tannin functionalized graphene nanoplatelets produced via ball-milling for sustainable soy protein-based film

A simple and green natural spider silk inspired strategy is proposed for fabricating advanced soy protein (SP)-based film by introducing Acacia mangium tannin (AMT) functionalized graphene nanoplatelets (AMT-GnPs), greenly and cost-effectively produced via ball milling graphite with AMT. The prepared film, namely SPEI/GnPs, exhibited noticeable improvement in mechanical properties over the neat SP-based film such as tensile strength (11.60 vs. 2.19 MPa) and toughness (21.12 vs. 3.09 MJ m-3). In addition, such developed biomimetic film still exhibited a high strain at failure (220.3%). The outstanding performance was attributable to the formation of dense interfacial covalent and H-bonding interactions between the scattered AMT-GnPs and the protein matrix. Moreover, after incorporating AMT-GnPs, the SPEI/GnPs film featured excellent UV-blocking performance and good water resistance. Overall, this study offers a facile biomimetic strategy for strong, tough, and biodegradable films for many potential applications like packaging and UV-blocking bioproducts.

Preparation of Pt electrocatalyst supported by novel, Ti(1\u2212x)MoxO2-C type of composites containing multi-layer graphene

Ball milling is a relative simple and promising technique for preparation of inorganic oxide–carbon type of composites. Novel TiO2-C and Ti0.8Mo2O2-C type of composites containing multi-layer graphene were prepared by ball milling of graphite in order to get electrocatalyst supports for polymer electrolyte membrane fuel cells. Starting rutile TiO2 was obtained from P25 by heat treatment. Carbon-free Ti0.8Mo2O2 mixed oxide, prepared using our previously developed multistep sol–gel method, does not meet the requirements for materials of electrocatalyst support, therefore parent composites with Ti0.8Mo2O2/C = 75/25, 90/10 and 95/5 mass ratio were prepared using Black Pearls 2000. XRD study of parent composites proved that the oxide part existed in rutile phase which is prerequisite of the incorporation of oxophilic metals providing CO tolerance for the electrocatalyst. Ball milling of TiO2 or parent composites with graphite resulted in catalyst supports with enhanced carbon content and with appropriate specific surface areas. XRD and Raman spectroscopic measurements indicated the changes of graphite during the ball milling procedure while the oxide part remained intact. TEM images proved that platinum existed in the form of highly dispersed nanoparticles on the surface of both the Mo-free and of Mo-containing electrocatalyst. Electrocatalytic performance of the catalysts loaded with 20 wt% Pt was studied by cyclic voltammetry, COads-stripping voltammetry done before and after the 500-cycle stability test, as well as by the long-term stability test involving 10,000 polarization cycles. Enhanced CO tolerance and slightly lower stability comparing to Pt/TiO2-C was demonstrated for Pt/Ti0.8Mo2O2-C catalysts.

Ball-Mill Assisted Green One-Pot Synthesis of ZnO/Graphene Nanocomposite for Selective Electrochemical Sensing of aquatic pollutant 4-nitrophenol

ZnO, having good transparency, high electron mobility and lower electrical noise, is an excellent material for electrochemical studies. Due to its high surface area and electrical conductivity, graphene is well suitable for the good dispersion of metal oxides for electronic/electrochemical applications. Graphene prevents particle agglomeration, whereas the addition of metal oxide prevents layer restacking in graphene. The bulk preparation of graphene via cost-effective and green methods are preferred. The aromatic conjugated π-network along the whole surface is not attained in large scale graphite oxide assisted production due to the defects and functional groups introduced during the hazardous synthetic procedure. Here, less defective graphene is synthesised via ball milling of graphite using metal oxalate as an exfoliating agent for the first time. Calcination of metal oxalate inserted graphite leads to the enormous evolution of gases thereby sliding the graphitic layers, leading to the formation of graphene sheets decorated with ZnO spherical nanoparticles’ bunches. The layer exfoliation and metal oxide incorporation are achieved here via a one-pot synthesis strategy. The use of ZnO/graphene in the selective sensing of 4-nitrophenol is investigated using cyclic voltammetric measurements in the presence of interfering compounds such as glucose, uric acid, ascorbic acid and H2O2.

Ball-Milling Graphite Used for Synthesis of Biocompatible Blue Luminescent Graphene Quantum Dots

Graphene Quantum Dots (GQDs) have been prepared by oxidationhydrothermal reaction, using ball-milling graphite as the starting materials. The prepared GQDs are endowed with excellent luminescence properties, with the optimum emission of 320nm. Blue photoluminescent emitted from the GQDs under ultraviolet light. The GQDs are ~3nm in width and 0.5~2 nm in thickness, revealed by high-resolution transmission electron microscopy and atomic force microscopy. In addition, Fourier transform infrared spectrum evidences the existence of carbonyl and hydroxyl groups, meaning GQDs can be dispersed in water easily and used in cellar imaging, and blue area inside L929 cells were clearly observed under the fluorescence microscope. Both low price of raw material and simple prepared method contribute to the high quality GQDs widespread application in future.

Fabrication of the amphiphilic hyperbranched poly(ether amine)@graphene (hPEA‐AN@G) hybrid assemblies by ball milling

AbstractOrganic–inorganic hybrid assembly is a very attractive means for constructing complex functional materials. Here, a simple method for the preparation of amphiphilic hybrid graphene nanosheets (hPEA‐AN@G) is developed via the in situ hybrid assembly of anthracene‐ended hyperbranched poly(ether amine) (hPEA‐AN) and graphene by ball milling graphite in aqueous solution with hPEA‐AN. The amphiphilic hPEA‐AN, consisting of hydrophilic hPEA chains and electron‐rich π‐conjugated aromatic AN capped on the periphery, not only interacts strongly with graphene nanosheets and water molecules but also endows the hybrid hPEA‐AN@G assemblies with hydrophilic surfaces and functional groups. The concentration of the resulting few‐layered hPEA‐AN@G is as high as 3.5 mg mL–1. Moreover, the total interaction energy (VT) of hPEA‐AN@G is VT,max = 4.2 meV nm–2 calculated according to the classical Derjaguin–Landau–Verwey–Overbeek theory, as high as 16 800 eV for a 2 μm × 2 μm graphene flake, suggesting a high stability of the hPEA‐AN@G assemblies. The as‐prepared hPEA‐AN@G can be redispersed well in several organic solvents including N,N‐dimethylformamide, 1,4‐dioxane, acetone and ethanol for more than 3 months. The superior performance and convenient fabrication make this method very promising for the production of graphene nanosheets on a large scale in both aqueous and organic solution. © 2021 Society of Industrial Chemistry.