Inorganic Fullerenes Research Articles

K2(Bi@Pd12@Bi20)]4-: An Endohedral Inorganic Fullerene with Spherical Aromaticity.

Inorganic fullerene clusters have attracted widespread attention due to their highly symmetrical geometric structures and intrinsic electronic properties. However, cage-like clusters composed of heavy metal elements with high symmetry are rarely reported, and their synthesis is also highly challenging. In this study, we present the synthesis of a [K2(Bi@Pd12@Bi20)]4- cluster that incorporates a {Bi20} cage with pseudo-Ih symmetry, making it the largest main group metal cluster compound composed of the bismuth element to date. Magnetic characterization and theoretical calculations suggest that the spin state of the overall cluster is a quartet. Quantum chemical calculations reveal that the [Bi20]3- cluster has a similar electronic configuration to C606- and the [Bi@Pd12@Bi20]6- cluster exhibits a unique open-shell aromatic character.

High performance inorganic fullerene cage WS2 enhanced cement

An original cement based material enhanced with inorganic fullerene tungsten disulfide (IF-WS2) nanoparticles has been engineered with superb shock absorbing properties. Physical properties were attributed to the IF-WS2 nano-hollow multiple layered onion-like structure. The effect of IF-WS2 concentration at 0.1 wt%, 1 wt% and 5 wt% on the hydration kinetics of ordinary Portland cement (CEM1), electrical impedance, thermal stability, rheology and strength development was thoroughly evaluated. X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and X-ray diffraction (XRD) studies confirmed the formation of the new phase, calcium tungstate (CaWO4), at the nano-particle/cement matrix interface during early hydration. 1 wt% IF-WS2 additions enhanced the impact energy of CEM1 by 89% compared to the control. An IF-WS2 cementitious mixture was developed for 3D printing based on the 1% WS2-CEM composition. The mix exhibited excellent workability and buildability enabling the creation of a layer-by-layer printed component. Intimate interlayer adhesion minimized the presence of voids leading to a high flexural strength of 6.7 MPa, which equated to an over 86% improvement compared to plain CEM1 printed components. This study showcases IF-WS2 nanoparticles as a new ground-breaking additive enabling the production of high-performance cementitious construction materials, for use under extreme environments demanding high strength and impact resistance.

Rational Design, Stabilities and Nonlinear Optical Properties of Non-Conventional Transition Metalides; New Entry into Nonlinear Optical Materials.

Electronic and nonlinear optical properties of endohedral metallofullerenes are presented. The endohedral metallofullerenes contain transition metal encapsulated in inorganic fullerenes X12Y12 (X = B, Al & Y = N, P). The endohedral metallofullerenes (endo-TM@X12Y12) possess quite interesting geometric and electronic properties, which are the function of the nature of the atom and the size of fullerene. NBO charge and frontier molecular orbital analyses reveal that the transition metal encapsulated Al12N12 fullerenes (endo-TM@Al12N12) are true metalides when the transition metals are Ni, Cu and Zn. Endo-Cr@Al12N12 and endo-Co@Al12N12 are at the borderline between metalides and electrides with predominantly electride characteristics. The other members of the series are excess electron systems, which offer interesting electronic and nonlinear optical properties. The diversity of nature possessed by endo-TM@Al12N12 is not prevalent for other fullerenes. Endo-TM@Al12P12 are true metalides when the transition metals are (Cr-Zn). HOMO-LUMO gaps (EH-L) are reduced significantly for these endohedral metallofullerenes, with a maximum percent decrease in EH-L of up to 70%. Many complexes show odd-even oscillating behavior for EH-L and dipole moments. Odd electron species contain large dipole moments and small EH-L, whereas even electron systems have the opposite behavior. Despite the decrease in EH-L, these systems show high kinetic and thermodynamic stabilities. The encapsulation of transition metals is a highly exergonic process. These endo-TM@X12Y12 possess remarkable nonlinear optical response in which the first hyperpolarizability reaches up to 2.79 × 105 au for endo-V@Al12N12. This study helps in the comparative analysis of the potential nonlinear optical responses of electrides, metalides and other excess electron systems. In general, the potential nonlinear optical response of electrides is higher than metalides but lower than those of simple excess electron compounds. The higher non-linear optical response and interesting electronic characteristics of endo-TM@Al12N12 complexes may be promising contenders for potential NLO applications.

Selective laser sintering of functionalized carbon nanotubes and inorganic fullerene-like tungsten disulfide reinforced polyamide 12 nanocomposites with excellent fire safety and mechanical properties

More effective and safe fire prevention solutions for polymer derivatives are necessary to address rising environmental and health concerns. In this study, the novel and simple chemically modified multi-walled carbon nanotubes (H-CNT) and PEGylated inorganic fullerene tungsten sulphide (P-IF-WS2) reinforced PA12 nanocomposites are synergistically prepared via selective laser sintering (SLS). The PA12/H-CNT/IF-WS2 nanocomposites show a wider sintering window than blank PA12. The formed hydrogen bond network of inter-chain contacts and compatibility in PA12/H-CNT/P-IF-WS2 matrix is proved. Furthermore, a dense carbon layer is developed by further dehydrating the oxygen-rich functional groups on the surface of H-CNT and P-IF-WS2 during carbonization at high temperatures. The PA12/H-CNT/P-IF-WS2 nanocomposites fabricated by incorporating hydrogen and carbon bonds in the PA12-based nanocomposites demonstrate good fire safety, thermal, and mechanical properties. The significant reduction in total heat release (20.14%), peak heat release (38.9%), and total smoke emission (22.6%) showed the improved fire safety of PA12. The H-CNT and P-IF-WS2 nanofillers also enhanced the mechanical (tensile and dynamic mechanical) capabilities. This technique of introducing nano-additives to SLS samples changes offers a practical, long-lasting, and effective way to improve the flame retardancy of laser-sintered polymer nanocomposites.

Cationic Polymerized Epoxy and Radiation Cured Acrylate Blend Nanocomposites Based on WS2 Nanoparticles—Part A: Curing Processes and Kinetics

Cationic photo-initiated and polymerized epoxies are characterized by good adhesion, high modulus, zero volatiles, low shrinkage and living polymerization characteristics. Radiation—cured acrylate resins are characterized by rapid initial curing with increased initial strength. The combination of radiation-cured acrylates and epoxies may present advantageous attributes. Thus, the system investigated is a hybrid epoxy/methyl acrylate and three different initiators for cationic polymerization of epoxies, the radical reaction of acrylates and the thermal initiator. When incorporating additives like opaque WS2 nanoparticles (NPs), absorption of the photo radiation takes place, which may lead to low photo activity. Curing kinetics measurements revealed that the absorbing/masking effect of WS2 was insignificant, and surprisingly, the level of curing was enhanced when the WS2 NPs were incorporated. FTIR results demonstrated that covalent bonds were formed between the inorganic fullerenes (IF-WS2) and the crosslinked matrix. Viscosity measurements showed a surprising reduction of five to ten times in the low-shear viscosity upon NPs incorporation compared to neat resins. It was concluded that the decrease of viscosity by the inorganic NPs, in addition to the enhanced level of conversion, has profound advantages for structural adhesives and 3D printing resins. To the best of our knowledge, this investigation is the first to report on a radiation-induced curing system containing opaque WS2 NPs that leads to an enhanced degree of curing and reduced shear viscosity.

Decrypting the Potential of Nanotechnology-Based Approaches as Cutting-Edge for Management of Hyperpigmentation Disorder.

The abundant synthesis and accretion of melanin inside skin can be caused by activation of melanogenic enzymes or increase in number of melanocytes. Melasma is defined as hyperpigmented bright or dark brown spots which are symmetrically distributed and have serrated and irregular borders. The three general categories of pigmentation pattern include centro facial pattern, malar pattern, and mandibular pattern. Exposure to UV rays, heat, use of cosmetics and photosensitizing drugs, female sex hormonal therapies, aberrant production of melanocyte stimulating hormone, and increasing aesthetic demands are factors which cause the development of melasma disease. This review gives a brief overview regarding the Fitzpatrick skin phototype classification system, life cycle of melanin, mechanism of action of anti-hyperpigmenting drugs, and existing pharmacotherapy strategies for the treatment of melasma. The objectives of this review are focused on role of cutting-edge nanotechnology-based strategies, such as lipid-based nanocarriers, i.e., lipid nanoparticles, microemulsions, nanoemulsions, liposomes, ethosomes, niosomes, transfersomes, aspasomes, invasomes penetration-enhancing vesicles; inorganic nanocarriers, i.e., gold nanoparticles and fullerenes; and polymer-based nanocarriers i.e., polymeric nanoparticles, polymerosomes, and polymeric micelles for the management of hyperpigmentation.

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.

Low concentration of inorganic fullerene tungsten sulfide nanofiller to achieve cost‐effective and significant enhancement on thermal and dynamic mechanical properties of perfluoroalkoxy nanocomposites

AbstractSpecial insulated wires beyond the conventional pure perfluoroalkoxy (PFA) polymers need to be developed to meet the increasing thermal management and mechanical performance requirements. Advanced PFA nanocomposites enhanced by inorganic fullerene tungsten sulfide (IF‐WS2) nanoparticles have been fabricated by melt blending and hot press processes. Benchmarked against the PFA, the presence of IF‐WS2 nanoparticles in the composites resulted in a maximum tensile strength of 21.35 MPa and a maximum elongation at break of 275%, which are 66% and 149% higher than those of pure PFA, respectively. The nanocomposites with 0.5 wt% IF‐WS2 achieved a 17.5% increase in storage modulus, 26.8°C increase in the onset melt temperature, while 1 wt% IF‐WS2 increased the glass transition temperature (Tg) by 3.4°C and the crystallinity (χc) by up to 34.4%. And when the additional amount of IF‐WS2 nanomaterials is 0.25%, the best combination of performance is obtained.

Highly sensitive acetone sensor based on WO3 nanosheets derived from WS2 nanoparticles with inorganic fullerene-like structures

Metal oxide semiconductor (MOS) gas sensors are promising for applications in environmental monitoring, dangerous gas detection, and disease diagnosis. Seeking for advanced MOS sensing materials that possess high sensitivity and low limit of detection (LOD) at sub-ppm level is a great challenge. Here, we report the first creation of two-dimensional (2D) WO3 nanosheets by annealing of the inorganic fullerene (IF)-like WS2 nanoparticles that were prepared via sulfurization of WO3 nanoparticles. Transformation of WS2 to WO3 was realised during the annealing process, simultaneously accompanied by the collapse of the hollow IF-WS2 structures and the formation of tiny 2D WO3 nanosheets with a lateral size of 40−80 nm. The resulting 2D WO3 nanosheets exhibited highly enhanced acetone-sensing performance in terms of sensitivity, selectivity, and response/recovery rates compared with the WO3 nanoparticles used as precursor for the synthesis of the IF-WS2 nanoparticles. The nanosheets also demonstrated great repeatability, reliable long-term stability, and very low LOD, making them a promising candidate as gas sensor to detect breath acetone.

Design and Evaluation the Anti-Wear Property of Inorganic Fullerene Tungsten Disulfide as Additive in PAO6 Oil

Inorganic fullerene-like tungsten disulfide particles have been proved to have good anti-friction and anti-wear properties as lubricating materials. As far as we know, however, when it is used as a lubricant additive, its behavior and action mechanism in the friction process are rarely studied. Herein, IF–WS2 particles were synthesized by a Chemical Vapor Deposition (CVD) method. The effect of IF–WS2 particle concentrations in the PAO6 oil on the tribological behaviors was investigated with a four-ball wear machine at both 75 and 100 °C. Additionally, the analyzed morphology and composition of nanomaterials and worn surfaces were analyzed by Scanning electron microscopy (SEM), Transmission Electron Microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The friction behavior in actual working conditions was studied by a wear testing machine. The experimental results show that compared with the original PAO6 oil, at a dispersion of 0.25 wt% in PAO6 oil, the IF–WS2 particles showed the best performance in terms of coefficient of friction, wear scar diameter and wear mass, which significantly reduced by 27%, 43% and 87%, respectively. At the same time, in the process of friction, it was found that IF–WS2 particles accumulated in the depressions to fill the scratches, and adsorption films and chemical films, including FeS2, WS2 and WO3, were formed on the worn surfaces to avoid the direct contact among the friction pairs more effectively, resulting in the improved anti-wear performances. Additionally, the addition of IF–WS2 particles effectively delayed the rise of lubricating oil temperature. In addition, dispersant span 80 can effectively improve the dispersion and stability of IF–WS2 in PAO6. This work provides us for understanding the effective lubrication mechanism of IF–WS2 particles in more detail and having a new acknowledge of the comprehensive performance of IF–WS2/PAO6 oil.

Inorganic electrides of alkali metal doped Zn12O12 nanocage with excellent nonlinear optical response

Finding new materials with exceptionally large nonlinear optical response is an interesting and challenging avenue for scientific research. Here, we report the alkali metal doped Zn12O12 nanocages as inorganic electrides with excellent nonlinear optical response. Density functional theory calculations have been performed for geometric, electronic and nonlinear optical response of exo- and endohedrally alkali metal doped Zn12O12 nanoclusters. For exohedral doping, all different possible doping sites are considered for decoration of alkali metal on the nanocage. The electride nature of the complexes is highly dependent on the position of alkali metal doping. All exohedral complexes except for alkali metal doping on six membered ring (r6) are electride in nature, as revealed from frontier molecular orbital analysis. Interaction energies reveal that all doped nanoclusters except endo-K@Zn12O12 are thermodynamically stable. The exothermic encapsulation of alkali metals in Zn12O12 nanocages is in marked contradiction with other inorganic fullerenes where encapsulation is an endothermic process. The barriers for boundary crossing are also evaluated in order study the interconversion of exo- and endohedral complexes. Doping of alkali metal significantly influences the properties of nanocages. HOMO-LUMO (H-L) gap is reduced significantly whereas hyperpolarizability is increased several orders of magnitude. The NLO response of exohedrally doped complexes is higher than the corresponding endohedral complexes, which is in mark contradiction with the behavior of phosphide or nitride nanocages. The highest first hyperpolarizability of 1.0 × 105 au is calculated for K@r6-Zn12O12 complex. Third order NLO response of these complexes is calculated and compared with the best systems reported in the literature at the same level of theory.

The dual effect of “inorganic fullerene” {Mo132} doped with SnO2 for efficient perovskite-based photodetectors

A simple doping method was used to modify SnO2 with polyoxometalate {Mo132}. The doped composite material not only has a more matched energy level and improves conductivity, but can also improve the quality of the perovskite film grown on it.

Nonlinear optical response of first-row transition metal doped Al12P12 nanoclusters; a first-principles study

The influence of first-row transition metals on structural, electronic, and nonlinear optical (NLO) properties of aluminum phosphide (Al12P12) inorganic fullerene is investigated through DFT methods. The designed M@Al12P12 composites are thermodynamically quite stable. Frontier orbital analysis revealed that HOMO–LUMO energy gap of Al12P12 nanocluster is fairly reduced in the presence of transition metals which is mainly attributed to the formation of new high HOMO energy levels due to excess electrons. Based on the NBO analysis, the charge is transferred from transition metal to the Al12P12 nanocluster. The calculated polarizability (αo) and the first hyperpolarizability (βo) values indicated that nonlinear optical response is remarkably enhanced under the influence of first-row transition metals. These M@Al12P12 composites possess giant first hyperpolarizabilities in the range of 3.1 × 102–5.9 × 106 au. This study may provide valuable insights for the designing of new high-performance materials for optoelectronic devices.

Investigation of Selected Polymer Composite-Aluminum Oxide Coating Tribological Systems

The tribotesting of friction systems requires discussion on proper selection of its conditions and data presentation. System tribology is based, for example, on analysis of the friction contact, the roughness of the cooperating surfaces, and the wear rate of the rubbing elements or coefficient of friction in relation to the sliding distance. Friction pairs, consisting of an aluminum alloy sample with an oxide layer (Al2O3) with and without the addition of inorganic fullerenes like tungsten disulphide (IF-WS2) nanoparticles on its surface cooperating with a counter-sample made of polymer composites prepared on the basis of phenol-formaldehyde resin with different fillers, were tested using a device with a pin-on-plate friction pair system. The results of the experiments showed sufficient durability of the Al2O3 and Al2O3/IF-WS2 oxide coatings in combination with the polymer composite. It was found that resin fillers such as cotton fibers, jute fibers, molybdenum disulphide (MoS2) or graphite (C) influence the friction behavior of the tribological pairs. Although the values of the coefficient of friction obtained in the tests were quite high, their course during the tests ensured stable cooperation of the aluminum coating/polymer composite friction pair on a 15 km distance, under a load of 0.5 MPa. The lowest coefficients of friction were obtained for oxide layers formed on aluminum combined with a polymer composite filled with cotton fibers and graphite. These studies provide information on the tribological properties of commercially available polymer composites cooperating with the produced oxide coatings, supplementing the available literature with the results of research on new, so far unexplored tribological partners. Microscopic investigation of the structure and morphology of the formed surface oxide layers and also microgeometry studies of both the friction elements were used to better understand the obtained research results.

Phase Behavior and Thermo-Mechanical Properties of IF-WS2 Reinforced PP-PET Blend-Based Nanocomposites.

The industrial advancement of high-performance technologies directly depends on the thermo-mechanical properties of materials. Here we give an account of a facile approach for the bulk production of a polyethylene terephthalate (PET)/polypropylene (PP)-based nanocomposite blend with Inorganic Fullerene Tungsten Sulfide (IF-WS2) nanofiller using a single extruder. Nanofiller IF-WS2 was produced by the rotary chemical vapor deposition (RCVD) method. Subsequently, IF-WS2 nanoparticles were dispersed in PET and PP in different loadings to access impact and their dispersion behavior in polymer matrices. As-prepared blend nanocomposites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), dynamic differential scanning (DSC), dynamic mechanical analysis (DMA), and X-ray diffraction (XRD). In this work, the tensile strength of the PP/PET matrix with 1% IF-WS2 increased by 31.8%, and the thermal stability of the sample PP/PET matrix with 2% increased by 18 °C. There was an extraordinary decrease in weight loss at elevated temperature for the nanocomposites in TGA analysis, which confirms the role of IF-WS2 on thermal stability versus plain nanocomposites. In addition, this method can also be used for the large-scale production of such materials used in high-temperature environments.

Convenient synthesis of inorganic fullerene-like WS2 self-lubricating films and their tribological behaviors

Abstract

MoS2 “inorganic fullerenes” combined with TiO2 in water-methanol suspensions: Highly active hydrogen production photo catalysts operating via transfer of accumulated electrons

Water-methanol suspensions of size-tuned hollow MoS2 “inorganic fullerenes” (IF) combined with high surface area anatase TiO2 efficiently promote photo catalytic hydrogen evolution reaction (PHER). Despite low amount of the MoS2 slabs edges in the structure of closed-shell IF-MoS2 particles and relatively poor dispersion of co-catalyst, the best composite catalysts were nearly 50% as active as Pt/TiO2 benchmark and considerably more active than the reference MoS2–TiO2 catalysts containing highly dispersed MoS2 slabs. Straightforward experimental evidence is given that hydrogen can be formed due to transfer of stored (accumulated) electrons from TiO2 to the IF-MoS2 particles in liquid suspension. Electrochemical flat band potential measurements support the possibility of electrons transfer from TiO2 to IF-MoS2.

Embedding alkenes within an icosahedral inorganic fullerene {(NH4)42[Mo132O372(L)30(H2O)72]} for trapping volatile organics.

Eight alkene-functionalized molybdenum-based spherical Keplerate-type (inorganic fullerene) structures have been obtained via both direct and multistep synthetic approaches. Driven by the opportunity to design unique host–guest interactions within hydrophobic, π-electron rich confined environments, we have synthesised {(NH4)42[Mo132O372(L)30(H2O)72]}, where L = (1) acrylic acid, (2) crotonic acid, (3) methacrylic acid, (4) tiglic acid, (5) 3-butenoic acid, (6) 4-pentenoic acid, (7) 5-hexenoic acid, and (8) sorbic acid. The compounds, which are obtained in good yield (10–40%), contain 30 carboxylate-coordinated alkene ligands which create a central cavity with hydrophobic character. Extensive Nuclear Magnetic Resonance (NMR) spectroscopy studies contribute significantly to the complete characterisation of the structures obtained, including both 1D and 2D measurements. In addition, single-crystal X-ray crystallography and subsequently-generated electron density maps are employed to highlight the distribution in ligand tail positions. These alkene-containing structures are shown to effectively encapsulate small alkyl thiols (1-propanethiol (A), 2-propanethiol (B), 1-butanethiol (C), 2-butanethiol (D) and 2-methyl-1-propanethiol (E)) as guests within the central cavity in aqueous solution. The hydrophobically driven clustering of up to 6 equivalents of volatile thiol guests within the central cavity of the Keplerate-type structure results in effective thermal protection, preventing evaporation at elevated temperatures (ΔT ≈ 25 K).

Alkaline earth metal decorated phosphide nanoclusters for potential applications as high performance NLO materials; A first principle study

Abstract With the aid of DFT calculations, novel inorganic complexes of group III phosphide (XY)12 (X = Al, B and Y = P) nanoclusters are theoretically designed and explored through exohedral doping with alkaline earth metals (Be, Mg, and Ca). The HOMO-LUMO gaps of the proposed novel inorganic complexes are narrowed significantly due to the increase in the energies of HOMOs. The results show that doping of alkaline earth metal over phosphide nanocluster causes shifting of excess electrons from the metal atom towards the nanocluster and breaks the centrosymmetry of the nanocluster. The doping profoundly increases the NLO response of the complexes. The first hyperpolarizabilities (βo) up to 7.8 × 104 au are calculated for the complexes as compared to the zero βo value of the pristine nanocage. These interesting results will attract more research interests in alkaline earth metal doped inorganic fullerenes complexes for the potential use in novel opto-electronic and high performance NLO materials and further the experimental research.

Revealing mechanical, tribological, and surface-wettability features of nanoscale inorganic fullerene-type tungsten disulfide dispersed in a polymer

Abstract