Ta2 Ni3 Se8 : 1D van der Waals Material with Ambipolar Behavior.

In this study, high-purity and centimeter-scale bulk Ta2 Ni3 Se8 crystals are obtained by controlling the growth temperature and stoichiometric ratio between tantalum, nickel, and selenium. It is demonstrated that the bulk Ta2 Ni3 Se8 crystals could be effectively exfoliated into a few chain-scale nanowires through simple mechanical exfoliation and liquid-phase exfoliation. Also, the calculation of electronic band structures confirms that Ta2 Ni3 Se8 is a semiconducting material with a small bandgap. A field-effect transistor is successfully fabricated on the mechanically exfoliated Ta2 Ni3 Se8 nanowires. Transport measurements at room temperature reveal that Ta2 Ni3 Se8 nanowires exhibit ambipolar semiconducting behavior with maximum mobilities of 20.3 and 3.52 cm2 V-1 s-1 for electrons and holes, respectively. The temperature-dependent transport measurement (from 90 to 295 K) confirms the carrier transport mechanism of Ta2 Ni3 Se8 nanowires. Based on these characteristics, the obtained 1D vdW material is expected to be a potential candidate for additional 1D materials as channel materials.

Designed growth of porous 2D Nb2O5 with Ag nano-particles for differential detection of UV-A and UV-C.

We demonstrate the differential detection of UV-A (ultra-violet 320-400 nm region) and UV-C (100-280 nm) using porous two-dimensional (2D) Nb2O5 and additional Ag nano-particle decoration. The 2D Nb2O5, which has band-absorption edge near the UV-A zone, was synthesized by thermodynamic conversion of 2D material NbSe2 (Nb2O5 has lower Gibbs formation energy than NbSe2). For the differential detection (to distinguish with UV-C absorption), we decorated the Ag nano-particles on the Nb2O5 surface. By coating Ag nano-particles, we can expect (i) a decrease in the area of light absorption by the Ag-coated area, and (ii) an increase of surface plasmon absorption by Ag nano-particles, especially the UV-A region, resulting in strong intensity ratio change UV-A/UV-C.

Colloidal Synthesis of Ultrathin and Se-Rich V2Se9 Nanobelts as High-Performance Anode Materials for Li-Ion Batteries.

In this study, the one-dimensional (1D) material V2Se9 was successfully synthesized using a colloidal method with VO(acac)2 and Se powder as precursors in a 1-octadecene solvent. The obtained colloidally synthesized V2Se9 (C-V2Se9) has an ultrathin nanobelt shape and a 4.5 times higher surface area compared with the bulk V2Se9, which is synthesized in a solid-state reaction as previously reported. In addition, all surfaces of C-V2Se9 are exposed to Se atoms, which is advantageous for storing Li through the conversion reaction into the Li2Se phase. Herein, the electrochemical performance of the C-V2Se9 anode material is evaluated; thus, the novelty of C-V2Se9 as a Se-rich 1D anode material is verified. The C-V2Se9 electrode exhibits a reversible capacity of 893.21 mA h g-1 and a Coulombic efficiency of 97.82% at the 100th cycle and excellent structural stability. Compared with the bulk V2Se9 electrode, the outstanding electrochemical performance of C-V2Se9 is attributed to its ultrathin nanobelt shape, high surface area, shorter Li diffusion length, and more electrochemically active sites. This work indicates the great potential of the Se-rich 1D material, C-V2Se9, as a post-transition metal dichalcogenide material for high-performance LIBs.

Organic Dispersion of Mo3Se3- Single-Chain Atomic Crystals Using Surface Modification Methods.

In this study, single-chain atomic crystals (SCACs), Mo3Se3-, which can be uniformly dispersed, with an atomically thin diameter of ∼0.6 nm were modified to disperse in an organic solvent. Various surfactants were chosen to provide steric hindrance to aqueous-dispersed Mo3Se3- by modifying the surface of Mo3Se3-. The organic dispersions of surface-modified Mo3Se3- SCACs in nonpolar solvent (toluene, benzene, and chloroform) were stable with a uniform diameter of 2 nm, and they have enhanced stability from oxidation (>10 days). With the surfactants that have a polystyrene tail group (PS-NH2), the surface-modified Mo3Se3- SCAC showed high compatibility with a polystyrene polymer matrix. Using the surface-modified Mo3Se3- SCAC, a homogeneous Mo3Se3-/polystyrene/toluene organogel was prepared. More importantly, the Mo3Se3-/polystyrene organogel exhibits significantly enhanced mechanical properties, with the improvement of 202.27% and 279.52% for tensile strength and elongation, respectively, compared with that of the pure organogel. The surface-modified Mo3Se3- had a similar structure with a polymer matrix, and the properties of the polymer can be improved even with a small addition of Mo3Se3-.

Tunable mechanical properties of Mo3Se3-poly vinyl alcohol-based/silk fibroin-based nanowire ensure the regeneration mechanism in tenocytes derived from human bone marrow stem cells.

Silk fibroin (SF) and poly vinyl alcohol (PVA)-based nanomaterial has exceptional attention in regenerative medicine. However, the preparation of SF and PVA-based nanomaterials in the desired form is complex due to their poor mechanical strength, brittleness, and compatibility. To this end, Mo3Se3 is chosen as a bio-nanowire to fabricate by combining PVA and SF to improve the mechanical properties. Physicochemical and structural features of the Mo3Se3-PVA-SF nanowire hydrogel (Mo3Se3-PVA-SF-NWH) were characterized by field emission scanning electron microscope (FE-SEM). Mechanical properties, degradation ratio, hydrophilicity, water uptake capacity, biocompatibility, and biological activity of the hydrogel were also studied. Superior interactions were formed between the reinforcing molecules of Mo3Se3 and PVA/SF in the hydrogel network by introducing Mo3Se3 nanowire (NW) into the hydrogel. Conversely, Mo3Se3 NW imparts mechanical stability and robustness to the blends (hydrogel) with predictable long-term degradation characteristics. It was proven by in vitro biodegradable rate, and swelling behaviour was varied depending on the concentration of Mo3Se3 NW. Mo3Se3 reinforced the hydrogels and found high porosity with superior biocompatibility. Excellent cellular adaptation was analyzed by MTT assay, live/dead staining, western blot, and quantitative real-time polymerase chain reaction (qRT-PCR). It revealed moderate toxicity at a concentration of 0.02% among the control samples. There was no discernible difference in 0.01% and 0.005% of Mo3Se3-PVA-SF-NWH in tenocytes derived from human bone marrow mesenchymal stem cells (hBMSC). Hence, this Mo3Se3-PVA-SF-NWH might be considered biocompatible due to its biological activities and appropriate mechanical properties. Overall, the Mo3Se3-PVA-SF-NWH might be considered a biocompatible scaffold for the possible biomedical applications of tendon tissue engineering.

Colloidal synthesis of 1-D van der Waals material Nb2Se9: study of synergism of coordinating agent in a co-solvent system.

Low-dimensional Nb2Se9 nanocrystals were synthesised through a simple one-pot colloidal synthesis with C18 organic solvents (octadecane, oleylalcohol, octadecanethiol, octadecene (ODE), and oleylamine (OLA)) of varied terminal functional groups. The solvent with high reducing power facilitated the nucleation of the nanoparticle, lowering threshold concentration and broadening the concentration spectrum. As a solvent, reducing agent, and capping agent, ODE functions as a primary factor in the synthesis of high-quality Nb2Se9 nanorods. We further discuss the unique adhesion role of ODE under the co-solvent system and demonstrate morphology control through synergism between ODE and OLA, verified by the electrochemical measurements.

A study on the bio-applicability of aqueous-dispersed van der Waals 1-D material Nb2Se9 using poloxamer.

In this research, dispersion of a new type of one-dimensional inorganic material Nb2Se9, composed of van der Waals bonds, in aqueous solution for bio-application study were studied. To disperse Nb2Se9, which exhibits hydrophobic properties in water, experiments were carried out using a block copolymer (poloxamer) as a dispersant. It was confirmed that PPO, the hydrophobic portion of Poloxamer, was adsorbed onto the surface of Nb2Se9, and PEO, the hydrophilic portion, induced steric hinderance to disperse Nb2Se9 to a size of 10 nm or less. To confirm the adaptability of muscle cells C2C12 to the dispersed Nb2Se9 using poloxamer 188 as dispersant, a MTT assay and a live/dead assay were performed, demonstrating improvement in the viability and proliferation of C2C12 cells.

One-dimensional van der Waals stacked p-type crystal Ta2Pt3Se8 for nanoscale electronics.

Recently, ternary transition metal chalcogenides Ta2X3Se8 (X = Pd or Pt) have attracted great interest as a class of emerging one-dimensional (1D) van der Waals (vdW) materials. In particular, Ta2Pd3Se8 has been actively studied owing to its excellent charge transport properties as an n-type semiconductor and ultralong ballistic phonon transport properties. Compared to subsequent studies on the Pd-containing material, Ta2Pt3Se8, another member of this class of materials has been considerably less explored despite its promising electrical properties as a p-type semiconductor. Herein, we demonstrate the electrical properties of Ta2Pt3Se8 as a promising channel material for nanoelectronic applications. High-quality bulk Ta2Pt3Se8 single crystals were successfully synthesized by a one-step vapor transport reaction. Scanning Kelvin probe microscopy measurements were used to investigate the surface potential difference and work function of the Ta2Pt3Se8 nanoribbons of various thicknesses. Field-effect transistors fabricated on exfoliated Ta2Pt3Se8 nanoribbons exhibited moderate p-type transport properties with a maximum hole mobility of 5 cm2 V-1 s-1 and an Ion/Ioff ratio of >104. Furthermore, the charge transport mechanism of Ta2Pt3Se8 was analyzed by temperature-dependent transport measurements in the temperature range from 90 to 320 K. To include Ta2Pt3Se8 in a building block for modern 1D electronics, we demonstrate p-n junction characteristics using the electron beam doping method.

High Breakdown Current Density in Quasi-1D van der Waals Layered Material Ta2NiSe7.

We synthesized ternary composition chalcogenide Ta2NiSe7, a quasi-one-dimensional (Q1D) material with excellent crystallinity. To utilize the excellent electrical conductivity property of Ta2NiSe7, the breakdown current density (JBD) according to thickness change through mechanical exfoliation was measured. It was confirmed that as the thickness decreased, the maximum breakdown voltage (VBD) increased, and at 18 nm thickness, 35 MA cm-2 of JBD was measured, which was 35 times higher than that of copper, which is commonly used as an interconnect material. By optimization of the exfoliation process, it is expected that through a theoretical model fitting, the JBD can be increased to about 356 MA cm-2. It is expected that the low-dimensional materials with ternary compositions proposed through this experiment can be used as candidates for current-carrying materials that are required for the miniaturization of various electronic devices.

Aqueous Dispersion of One-Dimensional van der Waals Material Mo6S3I6 with the Charge Type of the Hydrophobic Dispersant Tail.

Aqueous dispersion of van der Waals bonded one-dimensional materials Mo6S3I6 with hydrophobic surfaces has been studied. The surface charge of the dispersed Mo6S3I6 is controlled from negative to positive by the charge type of dispersant tail (anionic, SDS and NaDDBS; cationic, CTAB; nonionic, Poloxamer 407), and through this, it is possible to deposit the dispersed Mo6S3I6 in nanosized by electrophoretic deposition at a desired position. When a flexible device was manufactured by transferring Mo6S3I6, it was confirmed that electrical conductivity can be measured in 40% of elongation and more than 1000 times cyclic test.