Inorganic Fullerene-like Nanoparticles Research Articles

Addressing Irreversibility and Structural Distortion in WS2 Inorganic Fullerene-Like Nanoparticles: Effects of Voltage Cutoff Experiments in Beyond Li+-Ion Storage Applications.

Large interlayer spacing beneficially allows Na+- and K+-ion storage in transition-metal dichalcogenide (TMD)-based electrodes, but side reactions and volume change, which pulverize the TMD crystalline structure, are persistent challenges for the utilization of these materials in next-generation devices. This study first determines whether irreversibility due to structural distortion, which results in poor cycling stability, is also apparent in the case of inorganic fullerene-like (IF) tungsten disulfide (WS2) nanocages (WS2IF). To address these problems, this study proposes upper and lower voltage cutoff experiments to limit specific reactions in Na+/WS2IF and K+/WS2IF half-cells. Three-dimensional (3D) differential capacity curves and derived surface plots highlight the continuation of reversible reactions when a high upper cutoff technique is applied, thereby indirectly suggesting restricted structural dissolution. This resulted in improved capacity retention with stable performance and a higher Coulombic efficiency, laying the ground for the use of TMD-based materials beyond Li+-ion storage devices.

Elasto-hydrodynamic lubrication analysis of a porous misaligned crankshaft bearing operating with nanolubricants

In this paper, the combined effects of the characteristic size and concentration of inorganic fullerene-like tungsten disulphide nanoparticles (IF-WS2 NPs) or molybdenum disulphide nanoparticles (IF-MoS2 NPs) on the nonlinear dynamic behaviour of a gasoline engine crankshaft bearing subject to an arbitrary force torsor (effective applied force and moment vector) are theoretically and numerically investigated using the V. K. Stokes micro-continuum theory. These NPs are the most common additives for lubrication purposes due to their excellent tribological characteristics along with their effect on reducing friction and wear. It is assumed that the journal (crankshaft) currently made of a forged steel is rigid and the main bearing consists of a thin poroelastic liner made of low elastic modulus materials like Babbitt metals fixed in a stiff housing as defined by ASTM B23-00. The Krieger-Dougherty law is included in the proposed EHD model to account for the viscosity variation with respect to the volume fraction of nanoparticles dispersed in the base lubricant. On the other hand, the characteristic size of nanomaterials is introduced by a new material entity, denoted l, which is responsible for a couple-stress property. The Reynolds equation is derived in transient conditions and modified to account for the size of nanoparticles and the bearing-liner permeability property. For an arbitrary force torsor, the hydrodynamic pressure distribution, the squeeze film velocities, and the misalignment angular velocities are determined simultaneously by solving the discretized Reynolds equation and the equilibrium equations with the damped Newton-Raphson iterative method at each crank angle step. The crankshaft center trajectories in three sections of the main journal axis as well as the misalignment angles are deduced from the squeeze film velocities and the misalignment angular velocities by means of a Runge-Kutta scheme. According to the obtained results, the combined effects of the size and concentration of fullerene-like nanoparticles on the dynamic behavior of a compliant dynamically loaded crankshaft bearing operating with dynamic misalignment are significant and cannot be overlooked.

Biopolymer Nanocomposite Materials Based on Poly(L-lactic Acid) and Inorganic Fullerene-like WS2 Nanoparticles.

In the current study, inorganic fullerene (IF)-like tungsten disulphide (WS2) nanoparticles from layered transition metal dichalcogenides (TMDCs) were introduced into a poly(L-lactic acid) (PLLA) polymer matrix to generate novel bionanocomposite materials through an advantageous melt-processing route. The effectiveness of employing IF-WS2 on the morphology and property enhancement of the resulting hybrid nanocomposites was evaluated. The non-isothermal melt–crystallization and melting measurements revealed that the crystallization and melting temperature as well as the crystallinity of PLLA were controlled by the cooling rate and composition. The crystallization behaviour and kinetics were examined by using the Lui model. Moreover, the nucleating effect of IF-WS2 was investigated in terms of Gutzow and Dobreva approaches. It was discovered that the incorporation of increasing IF-WS2 contents led to a progressive acceleration of the crystallization rate of PLLA. The morphology and kinetic data demonstrate the high performance of these novel nanocomposites for industrial applications.

Tungsten Disulfide Inorganic Nanotubes Functionalized by PTFE for Friction Application

Inorganic nanotubes (INTs) and fullerene-like nanoparticles (NPs) of WS2/MoS2 penetrate and exfoliate at the contact interface and facilitate tribofilm formation. While the tribological properties are greatly improved by exfoliated NPs that shed easily, they may be diminished by agglomeration in oil. Therefore, surface functionalization is employed to improve dispersion in oil-based suspensions. Here, WS2 INTs were functionalized by polytetrafluoroethylene (PTFE) in a simple and cost-effective bath sonication method. WS2-INTs with two concentrations of added PTFE were characterized by scanning and transmission electron microscopy, micro-Raman spectroscopy, and thermogravimetric analysis. Superior distribution of WS2 was observed before and during friction experiments. Chemical analysis showed a significantly greater amount of PTFE-coated INTs on rubbed surfaces, in accordance with the improved friction and wear properties.

Inorganic fullerene-like nanoparticles and nanotubes of tungsten disulfide as reinforcement of carbon-epoxy composites

A possibility was examined to enhance carbon-epoxy laminated composite mechanical properties by introducing a small concentration of reinforcing nanostructures – multi-wall onion-shaped fullerene-like nanoparticles of tungsten disulfide IF-WS2, and its multi-layer hollow nanotubes, INT-WS2, both known for their outstanding thermal, chemical, and mechanical resistance. Composite structures were prepared using a unidirectional prepreg of strong carbon fibers and epoxy resin, poly (vinyl butyral) solution in ethanol with ultrasonically dispersed WS2 nanostructures in it. Particle size analysis has been performed to evaluate the quality of IF-WS2 nanoparticles. SEM/EDS analysis was applied to observe the nanostructures, their dispersion in the composite, and the fracture zone after mechanical resistance tests of the prepared composite samples. Thorough mechanical tests were performed on a set of specimens with different fiber orientations: tensile test, bending test, and interlaminar shear test. The encouraging results were obtained, indicating that these newly designed light-weight composites are applicable for the automotive and nautical industry, unmanned aerial vehicles, and military aircrafts.

Impact resistant hybrid composites reinforced with inorganic nanoparticles and nanotubes of WS2

Impact resistant nanocomposites are recognized as promising in saving lives in the car, skiing and bicycle accidents, preventing the failure of polymer-based prostheses and orthotic devices, as well as for various defense applications. This research reports improved impact and ballistic resistance of composite materials based on p-aramid fabric impregnated with phenolic resin and poly (vinyl butyral) (PVB), reinforced with small amounts of inorganic fullerene-like nanoparticles of tungsten disulfide (IF-WS2) and multiwall inorganic nanotubes (INT-WS2). The evaluation of the tensile testing resulted in significant improvements in the tensile strength (24.7%) and toughness (64.1%) for the composites with the addition of only 0.3 wt% INT-WS2 nanotubes. The impact toughness increased by 35.8%; the back-face deformation depths after shots were reduced by 12%; the absorbed energy of the knife stab 8.5% higher and the deformation depth 40.4% smaller than for the sample without the nanoreinforcement. The reaction of the composite material to shot impact was recorded by high-speed and infrared camera, to observe heating and cooling rates of the sample caused by dissipation of the kinetic energy of the shots.

Deposition of metal coatings containing fullerene-like MoS2 nanoparticles with reduced friction and wear

Self-lubricating films are of immense importance in various tribological applications. Nanoparticles are often used as the lubricating component in such films. Inorganic fullerene-like (IF) nanoparticles of WS2 have been used in the past for variety of tribological applications including for self-lubricating polymer and metallic films. IF nanoparticles from MoS2 with superior tribological behavior were reported in the past. However, such nanoparticles, which are available in minute amounts, were not applied for self-lubricating coatings in the past. In the current work, inorganic fullerene-like nanoparticles of MoS2 (IF-MoS2) were co-evaporated with titanium (cobalt) on metal substrates. The films were characterized by different techniques and were shown to have good adhesion to the underlying substrate. Furthermore, tribological tests indicated that such coatings exhibit improved friction coefficient (roughly 0.1) and very small wear under relatively high load.

Laser assisted synthesis of inorganic fullerene like MoS2-Au nanohybrid and their cytotoxicity against human monocytic (THP-1) cells

Here in, we report the investigation of the immunotoxicity of gold nanoparticles decorated on inorganic fullerene like MoS2 nanostructure (IFMoS2- AuNPs) on the THP-1 immune cell line. The MoS2 nanoparticle with fullerene like nanostructure (IFMoS2) was synthesized by double pulsed laser-assisted chemical vapour deposition (LCVD) method from bulk MoS2 at the temperature of 700 °C. The MoS2 inorganic fullerene-like nanoparticles grown by vapour-solid process (VS). The surface of the IFMoS2 was decorated with gold nanoparticles (AuNPs) to develop the semiconductor biocompatibility interface. The IFMoS2 are typically with diameters 20–50 nm as observed from the electron microscopy analysis. The stability of IFMoS2-AuNPs were examined by dynamic light scattering (DLS) and zeta potential measurements. The decoration of AuNPs on IFMoS2 surface was analyzed by UV–Vis, FTIR, PXRD, FESEM, EDX with elemental mapping and HRTEM measurement. The in vitro cytotoxicity evaluation of the FMoS2-AuNPs was determined on acute monocytic leukemic cells (THP-1) in which cell viability, caspase activity (CASP -3&7/CASP -8/CASP -9) and cell- structural changes were assessed. From FESEM revealed that IFMoS2-AuNPs induced apoptosis in THP-1 cells. Further, THP-1 cell viability markedly decreased at higher IFMoS2-AuNPs concentrations (65–100 μg/ml), indicating its potential as a chemotherapeutic agent in the treatment of human monocytic leukemia.

Metallic Nanocrystal Ripening on Inorganic Surfaces.

In this paper, we demonstrate the formation of hybrid nanostructures consisting of two distinctive components mainly in a one-to-one ratio. Thermolysis of inorganic nanotubes (INT) and closed-cage, inorganic fullerene-like (IF) nanoparticles decorated with a dense coating of metallic nanoparticles (M = Au, Ag, Pd) results in migration of relatively small NPs or surface-enhanced diffusion of atoms or clusters, generating larger particles (ripening). AuNP growth on the surface of INTs has been captured in real time using in situ electron microscopy measurements. Reaction of the AuNP-decorated INTs with an alkylthiol results in a chemically induced NP fusion process at room temperature. The NPs do not dissociate from the surfaces of the INTs and IFs, but for proximate IFs we observed fusion between AuNPs originating from different IFs.

Inorganic fullerene-like molybdenum selenide with good biocompatibility synthesized by laser ablation in liquids

The fabrication of inorganic fullerene-like nanoparticles (IFNPs) is an attractive idea due to their unique structures and various potential applications. To date, IFNPs have been made from numerous compounds with layered two-dimensional structures, based on various synthetic methods. Here we have demonstrated for the first time that inorganic fullerene-like molybdenum selenide nanoparticles (MoSe2 IFNPs) can be synthesized by laser ablating a molybdenum selenide target in 30 vol % ethanol/water mixture at ambient temperature and pressure. The formation mechanism was proposed to elucidate the production of MoSe2 IFNPs in the process of laser ablation in liquids (LAL). The appropriate solvent facilitates the condensation of the plasma plume created by LAL to planar MoSe2. Then, laser-induced high temperature and high pressure lead to the formation of a vacancy in the planar MoSe2, causing the generation of nucleation and growth of the MoSe2 IFNPs. In addition, a CCK-8 (cell counting kit-8) assay and a cell viability assay were performed to examine the cytotoxic behavior and the effect on cell viability of MoSe2 IFNPs. The results show that MoSe2 IFNPs are reasonably nontoxic and biocompatible with the given cells, showing they have significant potential in biomedical applications.

Decoration of Inorganic Nanostructures by Metallic Nanoparticles to Induce Fluorescence, Enhance Solubility, and Tune Band Gap

We report here a unique and efficient methodology for the surface functionalization of closed-cage inorganic fullerene-like (IF) nanoparticles and inorganic nanotubes (INTs) composed of two-dimensional nanomaterials of transition-metal chalcogenides (MS2; M = W or Mo). The first step is the physical coverage of these robust inorganic materials with monodispersed and dense monolayers of gold, silver, and palladium nanoparticles. The structural continuity at the interface between the IF/INT and the metallic nanoparticles is investigated. Lattice matching between these nanocrystalline materials and strong chemical affinity lead to efficient binding of the metallic nanoparticles onto the outer sulfide layer of the MS2-based structures. It is shown that this functionalization results in narrowing of the IF/INT optical band gap, increased work function, and improved surface-enhanced Raman scattering. In the second step, functionalization of the surface-bound nanoparticles is carried out by a ligand-exchange rea...

Testing of WS2 Nanoparticles Functionalized by a Humin-Like Shell as Lubricant Additives

Nanoparticles of transition metal dichalcogenides (TMDC) have been known to reduce friction and wear when added to oil-type liquid lubricants. Aggregation limits the ability of the nanoparticles to penetrate into the interface between the two rubbing surfaces—an important factor in friction reduction mechanisms. Doping has been successfully used to reduce agglomeration, but it must be done in the production process of the nanoparticles. The use of surface-functionalized nanoparticles is less common than doping. Nonetheless, it has the potential to reduce agglomeration and thereby improve the reduction of friction and wear. In this study, we present the results of preliminary tribological ball-on-flat tests performed with WS2 nanoparticles functionalized by a humin-like conformal shell, as additives to polyalphaolefin-4 (PAO-4) oil. We tested WS2 inorganic nanotubes (INTs) and two grades of inorganic fullerene-like nanoparticles (IFs). The shell/coating was found to improve friction reduction for IFs but not for INTs through better dispersion in the oil. The thicker the coating on the IFs, the less agglomerated they were. Coated industrial-grade IFs were found, by far, to be the best additive for friction reduction. We suggest the combination between reduced agglomeration and poor crystallinity as the reason for this result.

Al alloy metal matrix composites reinforced by WS2 inorganic nanomaterials

In the present work, advanced aluminium metal matrix composite reinforced by nanomaterials is reported. The materials used for the experiments are AA6061 aluminium alloy, compounded with inorganic nanotubes (INT) and fullerene-like (IF) nanoparticles of WS2. Aluminium metal matrix composite with different weight percentage (0.1–0.5wt%) of the INT and IF were prepared. Both the AA6061 aluminium and the aluminium metal matrix nanocomposites (MMCs) were re-melted by the stirring-casting method. Mechanical properties and microstructure analysis of the nano-MMCs were conducted.The measurements have shown that the hardness, yielding strength, ultimate tensile strength, and ductility were improved by up to 68% compared to the neat alloy for nanoparticles concentrations the range of 0.2wt%. Metallography microstructure analysis showed that increasing the WS2 INT or IF nanoparticles weight percentage in aluminium metal matrix composite, resulted in a more refined grains. The grain size of the composite matrix was reduced by up to 48.4% compared with that of neat AA6061 alloy ingot. Scanning electron microscope (SEM) analysis showed that addition of 0.5wt% of WS2 nanotubes into the Al matrix resulted in INT agglomeration which had deleterious effect on the tensile strength. The composite materials reinforcement mechanism was studied. This analysis showed that the improved mechanical properties of the metal nanocomposites can be predominantly attributed to the differences in thermal expansion coefficients of the WS2 INT (or WS2 IF nanoparticle) and the AA6061 alloy.

Inorganic Nanotubes and Fullerene-like Nanoparticles at the Crossroads between Solid-State Chemistry and Nanotechnology.

Inorganic nanotubes (NTs) and fullerene-like nanoparticles (NPs) of WS2 were discovered some 25 years ago and are produced now on a commercial scale for various applications. This Perspective provides a brief description of recent progress in this scientific discipline. The conceptual evolution leading to the discovery of these NTs and NPs is briefly discussed. Subsequently, recent progress in the synthesis of such NPs from a variety of inorganic compounds with layered (2D) structure is described. In particular, we discuss the synthesis of NTs from chalcogenide- and oxide-based ternary misfit layered compounds, as well as their structure and different growth mechanisms. Next we deliberate on the mechanical, optical, electrical, and electromechanical properties, which delineate them from their bulk counterparts and also from their graphene-like analogues. Here, different experiments with individual NTs coupled with first-principles and molecular dynamics calculations demonstrate the unique physical nature of these quasi-1D nanostructures. Finally, the various applications of the fullerene-like NPs of WS2 and NTs formed therefrom are deliberated. Foremost among the possibilities are their extensive uses as superior solid lubricants. Combined with their nontoxicity and their facile dispersion, these NTs, with an ultimate strength of about 20 GPa, are likely to find numerous applications in reinforcing polymers, adhesives, textiles, medical devices, metallic alloys, and even concrete. Other potential applications in energy-harvesting and catalysis are discussed in brief.

On the Mechanical Properties of WS2 and MoS2 Nanotubes and Fullerene-Like Nanoparticles: In Situ Electron Microscopy Measurements

Since the discovery of the first inorganic fullerene-like nanoparticles and nanotubes made of WS2 and then MoS2, many more compounds which produce such nanostructures have been discovered and added to the ever expanding list of this group of the layered nanomaterials. Scaling-up the synthesis of the nano-phases of WS2 and MoS2 together with their incredible mechanical properties has turned them into a most promising product for the lubrication industry. Fundamental studies on the mechanical properties of WS2 and MoS2 inorganic fullerene-like nanoparticles and nanotubes are presented in this review. A wide range of mechanical testing was conducted on WS2 and MoS2 nanoparticles. The main focus of this review will be on single nanoparticle experiments in situ electron microscopy as it enables simultaneous structure and properties characterization. Although it is quite challenging, the single nanoparticle approach provides us with the ability to elucidate the intrinsic properties of WS2 and MoS2 inorganic fullerenes and nanotubes.

Preparation of Ultrahigh Molecular Weight Polyethylene/WS2 Composites for Bulletproof Materials and Study on Their Bulletproof Mechanism

Ultrahigh molecular weight polyethylene (UHMWPE)/WS2 nanoparticle fibers were prepared by adding inorganic fullerene-like (IF) WS2 nanoparticles treated by a coupling agent to the precursor solution of UHMWPE. The influence of WS2 nanoparticles on the microstructure and properties of UHMWPE fibers were characterized by the scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and mechanical property measurements. The bulletproof performance of the UHMWPE/WS2 composite was tested by a bullet-shock test, and the bulletproof mechanism of the UHMWPE/WS2 composite was preliminarily studied. The results showed that WS2 nanoparticles could be uniformly dispersed in the UHMWPE fiber. After incorporating of WS2 nanoparticles, the UHMWPE fibers became stiffer and tougher than the pristine ones. In particular, the modulus of the fibers increased from 1203 to 1326 cN/dtex. The introduction of IF-WS2 nanoparticles led to significantly improved bulletproof performance of UHMWPE fibers.

Biocompatibility of tungsten disulfide inorganic nanotubes and fullerene-like nanoparticles with salivary gland cells.

Impaired salivary gland (SG) function leading to oral diseases is relatively common with no adequate solution. Previously, tissue engineering of SG had been proposed to overcome this morbidity, however, not yet clinically available. Multiwall inorganic (tungsten disulfide [WS2]) nanotubes (INT-WS2) and fullerene-like nanoparticles (IF-WS2) have many potential medical applications. A yet unexplored venue application is their interaction with SG, and therefore, our aim was to test the biocompatibility of INT/IF-WS2 with the A5 and rat submandibular cells (RSC) SG cells. The cells were cultured and subjected after 1 day to different concentrations of INT-WS2 and were compared to control groups. Growth curves, trypan blue viability test, and carboxyfluorescein succinimidyl ester (CFSE) proliferation assay were obtained. Furthermore, cells morphology and interaction with the nanoparticles were observed by light microscopy, scanning electron microscopy and transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy. The results showed no significant differences in growth curves, proliferation kinetics, and viability between the groups compared. Moreover, no alterations were observed in the cell morphology. Interestingly, TEM images indicated that the nanoparticles are uptaken by the cells and accumulate in cytoplasmic vesicles. These results suggest promising future medical applications for these nanoparticles.

Boundary lubrication: Influence of the size and structure of inorganic fullerene-like MoS2 nanoparticles on friction and wear reduction

The use of Inorganic Fullerene-like (IF) nanoparticles in lubricants has proved extremely effective to reduce friction and wear under severe boundary lubrication conditions. It has furthermore been suggested that the synthesis of smaller nanoparticles containing many structural defects would benefit friction and wear reduction, as they would penetrate and exfoliate more easily in the contact, leading to the quick formation of homogeneous tribofilms. In this study, four different types of IF-MoS2 were synthesized so as to be able to differentiate the influence of both the size and the morphology of the nanoparticles on their tribological behavior. Pure-sliding, reciprocating tribological testing of these four types of nanoparticles revealed their excellent friction-reducing properties in severe boundary lubrication, with splash lubrication taking place for a high number of cycles. High wear reduction was also obtained and confirmed using optical profilometry. Although the nanoparticle structure was found to have an influence on their effectiveness in time, all the nanoparticles tested – regardless of size or crystallinity – were found to achieve the same performances as long as proper oil recirculation took place, ensuring a continuous feeding of the contact in nanoparticles. The formation of MoS2 tribofilms on the wear surfaces was confirmed using XPS analyses and observed on FIB cross sections, and their nature was discussed in the light of the associated tribological results. As the size and morphology of the IF-MoS2 did not affect their performance in the range studied, their friction reducing properties were compared to those of bulk h-MoS2 tested in the same conditions. The benefits of using spherical nanoparticles such as IF-MoS2 was clearly shown.

One-step gas-solid reaction synthesis of W@WS2 nanorattles and their novel catalytic activity.

W@WS2 nanorattles were synthesised by heating a mixture of WO3 nanoparticles and S at a relatively low temperature between 750 and 950 °C in H2/Ar. In addition to the temperature, the competition between the H2 reduction and the S sulphidation sub-reactions dominated the reaction mechanisms and the morphologies of final products. Based on this, several types of nanostructures, including WS2 nanoflakes, inorganic fullerene-like nanoparticles and W@WS2 nanorattles (with desirable core size and shell thickness), could be selectively prepared by simply tailoring the processing parameters. Moreover, it was found for the first time that as-prepared W@WS2 nanorattles exhibited excellent catalytic activities which were close to or even better than their much more costive Au-based counterparts.

Thermoplastic Polymer Nanocomposites Based on Inorganic Fullerene-like Nanoparticles and Inorganic Nanotubes

Using inorganic fullerene-like (IF) nanoparticles and inorganic nanotubes (INT) in organic-inorganic hybrid composite, materials provide the potential for improving thermal, mechanical, and tribological properties of conventional composites. The processing of such high-performance hybrid thermoplastic polymer nanocomposites is achieved via melt-blending without the aid of any modifier or compatibilizing agent. The incorporation of small quantities (0.1–4 wt.%) of IF/INTs (tungsten disulfide, IF-WS2 or molybdenum disulfide, MoS2) generates notable performance enhancements through reinforcement effects and excellent lubricating ability in comparison with promising carbon nanotubes or other inorganic nanoscale fillers. It was shown that these IF/INT nanocomposites can provide an effective balance between performance, cost effectiveness, and processability, which is of significant importance for extending the practical applications of diverse hierarchical thermoplastic-based composites.