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Single-step growth of (0h0)-oriented MoO3 nanorods via radio frequency sputtering for humidity sensors.

1D van der Waals Nb2Se9 synthesized according to a co-solvent system presented an onset potential of 0.84 V and Tafel slope of 69.4 mV s−1 as an ORR electrocatalyst.

The gas adsorption/desorption reaction that occurs on a solid surface forms the basic reaction of various catalysts and sensor devices.

For the atomic unit dispersion of Mo3Se3− (a negatively charged atomic chain material that forms bulk crystals through ionic bonds with cations), LiMo3Se3 crystals were synthesized by an ion-exchange reaction from InMo3Se3 (InMo3Se3 + LiI → LiMo3Se3 + InI). The temperature- and time-dependent kinetics of the ion-exchange reaction were studied. The change in the lattice constant, obtained through X-ray diffraction analysis, showed a reaction pattern corresponding to random walk diffusion within the atomic chain. The temperature-specific experiments (Arrhenius plot) confirmed that the ion-exchange activation energy was approximately 0.565 eV. By dispersing the LiMo3Se3 synthesized through an optimized ion-exchange reaction in an aqueous solution, it was confirmed that the one-dimensional (1D) nanostructure was well dispersed. Based on the results of this experiment, it is expected that it will be possible to lay the foundation for the application of water-dispersible one-dimensional materials to various bio fields.

Al2O3 thin film was deposited on Gorilla glass using an aerosol deposition method to improve the mechanical property of cover glass for mobile electronic device. The deposited Al2O3 film (approximately 1 μm thick) was a polycrystalline structure and showed a high light transmittance of approximately 90% in the visible light region. The CIE color space (L*a*b) measurement also showed a characteristic corresponding to the acceptable optical range of the cover glass. Further, it was confirmed that the bending strength improved by 10 %, as compared with bare Gorilla glass (from 6970 kgf/cm2 to 7704 kgf/cm2), and the Vickers hardness increased to approximately 1700–2000 HV, as compared with that of Gorilla glass (

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.

Electrochemical dopamine (DA) detection has been extensively studied for the practical diagnosis of neurological disorders. A major challenge in this system is to synthesize selective and sensitive DA sensing electrocatalysts in extracellular fluids, because critical interferents such as uric acid (UA) and ascorbic acid (AA) exhibit oxidation potentials similar to those of DA. Herein, we report an extremely selective and sensitive electrocatalyst for DA sensing prepared by vanadium selenide (V2Se9). A solution-based process for the first time was introduced to synthesize the V2Se9, showing unique DA-philic characteristic caused by exposure negative charge of crystal Se. Owing to its distinctive features, the prepared V2Se9 electrode detected only DA in the presence of concentrated interferents. Electrochemical characterization and computing simulation provide strong evidence that the extreme DA selectivity stems from close physical affinity between Se and DA, leading to the outer sphere electron transfer mechanism. This is totally different from common catechol-based oxidation process. Furthermore, nano-structured V2Se9 electrode extremely improves DA sensing ability as low as practical detection limit with maintaining inactive interferent characteristic. More interestingly, an identical unique DA-sensing ability was also observed in a V2Se9 analogue—Nb2Se9. We believe that this finding provides new insights into the effect of the analyte-philic properties of electrode materials on the electrocatalytic response for selective analyte quantification.

A quasi-one-dimensional van der Waals metallic nanowire Nb

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.

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.

A hydrogen sensor was fabricated by utilizing a bundle of metal oxide nanostructures whose growth positions were selectively controlled by utilizing graphene, which is a carbon of atomic-unit thickness. To verify the reducing ability of graphene, it was confirmed that the multi-composition metal oxide V2O5 was converted into VO2 on the graphene surface. Because of the role of graphene as a reducing catalyst, it was confirmed that ZnO and MoO3 nanostructures were grown at high density only on the graphene surface. The fabricated gas sensor showed excellent sensitivity.

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.

Three-dimensional (3D) plasmonic structures have attracted great attention because abnormal wetting behavior of plasmonic nanoparticles (NPs) on 3D nanostructure can enhance the localized surface plasmons (LSPs). However, previous 3D plasmonic nanostructures inherently had weak plasmonic light absorption, low electrical conductivity, and optical transmittance. Here, we fabricated a novel 3D plasmonic nanostructure composed of Ag NPs as the metal for strong LSPs and 3D nano-branched indium tin oxide (ITO BRs) as a transparent and conductive framework. The Ag NPs formed on the ITO BRs have a more dewetted behavior than those formed on the ITO films. We experimentally investigated the reasons for the dewetting behavior of Ag NPs concerning the geometry of ITO BRs. The spherical Ag NPs are spatially separated and have high density, thereby resulting in strong LSPs. Finite-domain time-difference simulation evidenced that spatially-separated, high-density and spherical Ag NPs formed on ITO BRs dramatically boost the localized electric field in the active layer of organic solar cells (OSCs). Photocurrent of PTB7:PCBM OSCs with the ITO BRs/Ag NPs increased by 14%.

RuO2 nanorods on electrospun carbon nanofibers were simply grown by precipitation and recrystallization methods for studying their capacitive behaviors for supercapacitor applications. Recrystalliz...

Zn-doped MgO/Mg(OH)2 was used to increase thermal energy storage efficiency. Among general bulk materials, the thermal conductivity of those materials used for high-efficiency thermal energy storage should be high. In micro (or nano) structures, however, the lower the thermal conductivity, the heat can be more easily concentrated on the surface, enabling a thermodynamic reaction to store heat energy to be easily induced. Zn-doped MgO limits the vibration of the lattice and ultimately lowers the thermal conductivity. This reduced thermal conductivity increases the surface heat accumulation, and it was confirmed that dehydrogenation of Mg(OH)2 surfaces can occur rapidly, increasing the thermal energy storage efficiency.

We heat-treated an amorphous large-area WO3 thin film to synthesize high-density, high-quality WO3 nanorods. The WO3 nanostructures were effective, especially in reducing gas (hydrogen and helium) atmospheres. By electron microscopy analysis, we confirmed that the thermodynamic energy for forming oxygen vacancies in the [020] direction was low. We could apply self-crosslinked WO3 nanostructures to practical sensor device fabrication by simply placing the electrodes without complex processes such as transfer and e-beam lithography. It was used for the production of a UV detector, which reacted very fast (∼0.316 s) and was very sensitive to the actual UV-C (261 nm) wavelength. Also, plasmon-based light absorption through the Ag nanoparticle coating resulted in more than 350-fold improvement in the on/off process during UV-C irradiation.

Aqueous dispersion of van der Waals bonded one-dimensional materials Mo

A transparent and flexible film capable of shielding electromagnetic waves over a wide range of frequencies (X and K