Inorganic Fullerene-like 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.

Employment of Micro- and Nano-WS2 Structures to Enhance the Tribological Properties of Copper Matrix Composites

Friction and wear are responsible for around 23% of the energy consumption in transportation, manufacturing, power generation, and residential sectors. Employed components are exposed to a wide range of operational conditions, therefore a suitable material design is fundamental to decreasing tribological issues, energy consumption, costs, and environmental impact. This study aims to analyze the effect of different solid lubricants on the suitability of copper matrix composites (CuMCs) as a potential solution to reduce the depletion of sliding electrical contacts working under extreme conditions. CuMCs samples are produced by cold-pressing and sintering to merge a high electrical conductivity with the lubricant effect supplied by different species, namely tungsten disulfide micro-powder (WS2), inorganic fullerene-like (IF) tungsten disulfide nanoparticles, and graphene nanoplatelets (GNP). The crystalline structure of the pristine and composite materials is characterized via XRD. The electrical tests show a small decrease of conductivity compared to pure copper, due to the insulating effect of WS2; however, the measured values are still adequate for conduction purposes. Micro-scratch and wear tests highlight the positive effect of the combination of WS2 structures and GNP. The friction coefficient reduction leads to the possibility of extending the lifetime of the components.

Simultaneous formation of ultra-thin MoSe2 nanosheets, Inorganic Fullerene-Like MoSe2 and MoO3 quantum dots using fast and ecofriendly Pulsed Laser Ablation in Liquid followed by microwave treatment

This research reports a rapid and scalable synthesis of MoSe2 Nanosheets (NSs), Inorganic Fullerene-Like (IF) MoSe2 and MoO3 quantum dots (QDs) with varying morphologies and crystal structures using Pulsed Laser Ablation in Liquid (PLAL) technique followed by microwave treatment of Bulk-MoSe2 powders. We show that using water as a solvent result in the formation of MoO3 QDs, single and few layered MoSe2 NSs and IF-MoSe2 structures from both Laser Modified (LM) and Laser Microwave Modified (LMM) MoSe2 samples. The presence of the predominant A1g mode in the Raman spectra of LM-MoSe2 and LMM-MoSe2 samples further showed the formation of single layer MoSe2 NS. Moreover, formation of small-sized MoSe2 heterolayers with an expanded interlayer spacing along the (002) planes for LMM samples which were subjected to microwave treatment for 30 min was demonstrated. Comparatively, for the samples subjected to microwave treatment for 60 min, most of the crystal orientations were vertical. The current study showed the controllable crystal orientation in MoSe2 samples by combined PLAL and microwave treatment. The two successive microwave steps led to change in the MoSe2 crystal orientation from horizontal to vertical. Selective oxygen incorporation induced by both PLAL and microwave treatment was also shown along the (100) and (002) planes for LM-MoSe2 and LMM-MoSe2, respectively. Understanding the selective oxygen incorporation in MoSe2 planes can shed light on the precise control of oxygenation in the crystal structures of 2D nanomaterials, synthesized heterostructures and nanocomposites.

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.

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.

Influence of the Size of Nanoparticles on the Microstructure of Oxide Coatings

The microstructures and structures of composite coatings prepared on aluminum substrates are studied. Amorphous oxide layers Al2O3 are obtained on EN AW 5251 aluminum alloy. In the Al2O3 coatings, two kinds of inorganic fullerene-like (IF) tungsten disulfide (WS2) nanoparticles (NPs) are introduced by a dip coating method. In order to show the difference between the possibilities of introducing NPs in the microstructure of Al2O3, we carried out the scanning electron microscopy and transmission electron microscopy analyses. The image processing and analysis were performed in order to study the shapes and sizes of the IF-WS2 nanoparticles. Visual comparative analysis reveals the difference in the quality of nanopowders that greatly affects their ability to form agglomerates and, hence, strongly affects the possibility of introducing NPs into nanopores.

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...

Short Pulse Laser Synthesis of Transition-Metal Dichalcogenide Nanostructures under Ambient Conditions.

The study of inorganic nanometer-scale materials with hollow closed-cage structures, such as inorganic fullerene-like (IF) nanostructures and inorganic nanotubes (INTs), is a rapidly growing field. Numerous kinds of IF nanostructures and INTs were synthesized for a variety of applications, particularly for lubrication, functional coatings, and reinforcement of polymer matrices. To date, such nanostructures have been synthesized mostly by heating a transition metal or oxide thereof in the presence of precursor gases, which are however toxic and hazardous. In this context, one frontier of research in this field is the development of new avenues for the green synthesis of IF structures and INTs, directly from the bulk of layered compounds. In the present work, we demonstrate a simple room-temperature and environmentally friendly approach for the synthesis of IF nanostructures and INTs via ultrashort-pulse laser ablation of a mixture of transition-metal dichalcogenides in bulk form mixed with Pb/PbO, in ambient air. The method can be considered as a synergy of photothermally and photochemically induced chemical transformations. The ultrafast-laser-induced excitation of the material, complemented with the formation of extended hot annealing regions in the presence of the metal catalyst, facilitates the formation of different nanostructures. Being fast, easy, and material-independent, our method offers new opportunities for the synthesis of IF nanostructures and INTs from different bulk metal chalcogenide compounds. On the basis of the capabilities of laser technology as well, this method could advantageously be further developed into a versatile tool for the simultaneous growth and patterning of such nanostructures in preselected positions for a variety of applications.

Novel graphitic carbon coated IF-WS2reinforced poly(ether ether ketone) nanocomposites

Unique high performance thermoplastic PEEK ternary nanocomposites reinforced by nano graphitic carbon coated IF (inorganic fullerene-like)-WS2have been prepared and their structures have been characterised by XRD, EDX and HR-TEM.

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.

Re-doped fullerene-like MoS2 nanoparticles in relationship with soft lubrication

Inorganic, fullerene-like (IF) nanoparticles of tungsten disulfide (WS2) and molybdenum disulfide (MoS2) have been synthesised in the past and their useful tribological properties have been studied quite extensively. Rhenium doping of such nanoparticles was also reported and studied to some extent. Herein, further studies of the physico-chemical properties are reported in connection to lubrication under mild loads. Due to their self-repelling character, the doped nanoparticles form tessellated monolayers on certain substrates. When mixed in small amounts, the IF nanoparticles lead to a reduction in the viscosity of water-based gels. Furthermore, the added nanoparticles lead to a precipitous reduction in traction force (friction) under mild loads. The lubrication mechanism of such nanoparticles is briefly discussed.

Fullerene‐like Re‐Doped MoS2 Nanoparticles as an Intercalation Host with Fast Kinetics for Sodium Ion Batteries

AbstractSodium ion batteries (SIBs) are considered as a promising alternative to threaten the reign of lithium ion batteries (LIBs) among various next‐generation rechargeable energy storage systems, including magnesium ion, metalair, and metalsulfur batteries. Since both sodium and lithium are located in Group 1 of the periodic table, they share similar (electro)chemical properties with regard to ionization pattern, electronegativity, and electronic configuration; thus the vast number of compounds developed from LIBs can provide guidance to design electrode materials for SIBs. However, the larger ionic radius of the sodium cation and unique (de)sodiation processes may also lead to uncertainties in terms of thermodynamic or kinetic properties. Herein, we present the first construction of SIBs based on inorganic fullerene‐like (IF) MoS2 nanoparticles. Closed‐shell‐type structures, represented by C60 fullerene, have largely been neglected for studies of alkali‐metal hosting materials due to their inaccessibility for intercalating ions into the inner spaces. However, IF‐MoS2, with faceted surfaces, can diffuse sodium ions through the defective channels, thereby allowing reversible sodium ion intercalation/deintercalation. Interestingly, Re‐doped MoS2 showed good electrochemical performances with fast kinetics (ca. 74 mA h g−1 at 20 C). N‐type doping caused by Re substitution of Mo in IF‐MoS2 revealed enhanced electrical conductivity and an increased number of diffusion defect sites. Thus, chemical modification of fullerene‐like structures through doping is proven to be a promising synthetic strategy to prepare improved electrodes.

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.

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.

Decoupling reduction–sulfurization synthesis of inorganic fullerene-like WS2 nanoparticles in a particulately fluidized bed

A novel decoupling reduction–sulfurization process for the synthesis of inorganic fullerene-like (IF) WS2 nanoparticles has been developed in this work. In this strategy, the raw WO3 nanoparticles are firstly reduced by hydrogen in a fluidized bed, followed by sulfurization with H2S in a reducing atmosphere. The diffusion and reaction are the two kinetic factors playing important roles in controlling the structure of WS2. Under diffusion limitation, the porous β-W phase and inordinate WS2 structure are formed, while the α-W phase and IF-WS2 structure are usually obtained in the reaction-limited condition. The particulate fluidization of the reduced WO3 nanoparticles in the agglomerates forms is realized in this decoupling reduction–sulfurization process. The porous β-W nanoparticles and their particulate fluidization enhance the diffusion of H2S, resulting in the completion of sulfurization reaction in short time. This newly developed approach is efficient and cost-effective, and might be extended to the large-scale synthesis of other inorganic fullerene-like metal sulfides.

The effect of tungsten disulphide nanoparticles on the properties of polyurethane adhesives

Thermoset-elastomer polyurethane (PU) nanocomposites were prepared using two types of tungsten disulphide (WS2) nanoparticles: inorganic fullerene-like (IF) and inorganic nanotubes (INT) through an in-situ polymerization process. The quality of dispersion was evaluated using scanning electron microscope (SEM) and the thermomechanical properties were analyzed using dynamic mechanical analysis (DMA). Addition of 1% and 3 wt.%. IFs resulted in enhancement in storage modulus of 45 and 100%, respectively, compared to the neat polymer. The enhancement using only 0.5% wt. INTs was more than 100% and then decreased with additional amount of nanotubes. While no significant change in the composite’s glass transition temperature (Tg) was observed with IF-WS2, 0.5% INT-WS2 showed a 20 °C increase of Tg. In both cases, analysis of the chemical structure using an attenuated total reflectance- Fourier transform infrared spectroscopy showed no effect of the nanoparticles on the chemical structure of the PU and wide-angle X-ray diffraction showed no change in morphology. In the case of IF-WS2 the highest peel strength was obtained with 1% wt. demonstrating a 44% improvement in peel strength. However, in the case of INT-WS2, incorporating 0.5% wt. improved the peel strength by more than 1000%. SEM analysis showed a unique development of a nodular morphology and a failure mechanism dominated by nanotube pull-out. It was concluded that the geometry of the nanoparticles (nanotubes or fullerene) has a dominant effect on the final PU nanocomposite properties.

Tribological performance of the epoxy-based composite reinforced by WS2 fullerene-like nanoparticles and nanotubes

Recently large amounts of inorganic nanotubes (INT) and inorganic fullerene-like (IF) nanoparticles of WS2 became available and methods for their dispersion in different media were developed. In the present work the tribological properties of epoxy composite compounded with tungsten disulfide particles of different sizes and morphologies, including quasi-spherical IF nanoparticles, one-dimensional INT as well as micron-size platelets (2H) were investigated. The coefficient of friction and wear loss were measured under dry contact conditions using different tribological rigs. Remarkable reduction in wear and also friction (under high load) was demonstrated for the IF/INT epoxy nanocomposite. The reduced wear is attributed in general to the reinforcement of the polymer matrix by nanoparticles and the simultaneous reduction of the epoxy brittleness. Contrarily, the friction of the neat epoxy sample and epoxy mixed with platelets was accompanied with strong wear and transfer of a polymer film onto the rubbed surfaces. These results are consistent with the recently reported improvements in the fracture toughness, peel and shear strength of the epoxy-nanoparticles (IF/INT) composites.

Codeposition of inorganic fullerene-like WS2 nanoparticles in an electrodeposited nickel matrix under the influence of ultrasonic agitation

Abstract The effects of ultrasound (US) agitation (at different intensities of ultrasound) on the codeposition of inorganic fullerene-like (IF) WS 2 in a metallic Ni matrix are investigated. The wt.% of IF-WS 2 particles in the nanocomposite coatings increases from 4.5 wt.% (in films grown under mechanical stirring but without US agitation) up to about 7 wt.% (in films prepared under US agitation at the optimum intensity of ultrasound). While composite coatings obtained only under mechanical stirring exhibit a rather irregular surface morphology, with pronounced 3D multinodular protrusions, a more uniform and compact coating is attained under application of US agitation. In turn, the introduction of WS 2 particles significantly modifies the growth of Ni, inducing grain size refinement, increasing the stacking fault probability and causing a drastic change of crystallographic texture. These microstructural features act in a synergistic manner to simultaneously increase the hardness of the composite coatings while causing the expected decrease in the friction coefficient (due to the presence of WS 2 solid lubricant particles), therefore enhancing the wear resistance, particularly when the coatings are deposited under the presence of US.

Photocatalysis with hybrid Co-coated WS2 nanotubes

Inorganic fullerene-like (IF) nanoparticles (NP) and inorganic nanotubes (INT) of layered compounds, such as WS2, have been of particular interest due to their unique structural characteristics. Recently, the catalytic decomposition of thiophene using INT of WS2 decorated with Co NP was demonstrated. This finding also suggests that these materials could be also suitable for the photocatalytic treatment of pollutants in wastewaters. In the present work, the photocatalytic decomposition of methyl orange (MO) in aqueous solution using Co-coated INT-WS2 as well as other NP was investigated. The photocatalytic reactivity under visible light illumination of this photocatalyst was measured and compared with that of various IF and INT and TiO2 (P25). The Co NP-coated INT-WS2 exhibited the highest photodegradation of MO among the studied NP. The significant enhancement in the photoactivity of the hybrid nanostructure can be attributed to the combination of the metallic Co NP and the semiconducting WS2 nanotubes. The hybrid nanostructure enables the efficient light absorption by the INT and the subsequent charge separation of the hybrid semiconductor-metal NP under visible light illumination. In addition, Raman spectroscopy technique was used to verify that the MO was decomposed by Co-coated nanotubes and not adsorbed in large amounts on the hybrid NP surface.

Tribological studies of rhenium doped fullerene-like MoS2 nanoparticles in boundary, mixed and elasto-hydrodynamic lubrication conditions

The tribological properties of rhenium-doped inorganic fullerene-like MoS2 nanoparticles were studied in poly alpha olefin oil, and compared to inorganic fullerene-like (IF) MS2 (M=Mo,W) nanoparticles and 2H-MoS2 platelets. For this purpose a rotational disc tribometer was used. Different regimes in the Stribeck curve, i.e., boundary, mixed and elasto-hydrodynamic lubrication conditions were studied. A precipitous reduction in friction and wear of oil suspensions with nanoparticles were observed for the entire IF samples. However, Re-doped IF exhibited the best results, presumably due to their reduced tribocharging and agglomeration. The various tribological mechanisms of solid state additives are discussed.