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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. [ABSTRACT FROM AUTHOR]

Mass production of one-dimensional, V2Se9 crystals, was successfully synthesized using the solid-state reaction of vanadium and selenium. Through the mechanical exfoliation method, the bulk V2Se9 crystal was easily separated to nanoribbon structure and we have confirmed that as-grown V2Se9 crystals consist of innumerable single V2Se9 chains linked by van der Waals interaction. The exfoliated V2Se9 flakes can be controlled thickness by the repeated-peeling method. In addition, atomic thick nanoribbon structure of V2Se9 was also obtained on a 300 nm SiO2/Si substrate. Scanning Kelvin probe microscopy analysis was used to explore the variation of work function depending on the thickness of V2Se9 flakes. We believe that these observations will be of great help in selecting suitable metal contacts for V2Se9 and that a V2Se9 crystal is expected to have an important role in future nano-electronic devices. [ABSTRACT FROM AUTHOR]

Centimeter‐size single‐crystalline Nb3I8, a new family of two‐dimensional materials, is first synthesized by a vapor transport reaction of niobium and iodine. Through the mechanical exfoliation method, the bulk Nb3I8 crystal is cleaved to monolayer and multi‐layered flakes. It is confirmed to consist of numerous monolayers of Nb3I8 bonded by weak van der Waals interaction. By utilizing atomic force microscopy (AFM) and scanning Kelvin probe microscopy (SKPM), the information on structure and electrical properties is obtained at the same time. The analysis results show that the surface potential difference and the work function tend to increase as the Nb3I8 becomes thicker due to the interlayer screening effect. The results for the work function variation dependence on thickness are useful for selecting a suitable metal electrode for future Nb3I8‐based nano‐devices which can have a significant impact on performance. Centimeter‐size single‐crystalline Nb3I8 crystal, a new family of 2D materials, is firstly realized by a controlled solid‐state reaction of niobium and iodine. Since each layer of Nb3I8 is linked by a weak vdW forces, bulk Nb3I8 crystal is easily cleaved to monolayer and multi‐layered flakes by mechanical exfoliation. By utilizing the scanning Kelvin probe microscopy, the authors confirm that the surface potential difference and the work function tended to increase as the Nb3I8 become thicker due to the interlayer screening effect. [ABSTRACT FROM AUTHOR]

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) Nb 2 O 5 and additional Ag nano-particle decoration. The 2D Nb 2 O 5 , which has band-absorption edge near the UV-A zone, was synthesized by thermodynamic conversion of 2D material NbSe 2 (Nb 2 O 5 has lower Gibbs formation energy than NbSe 2 ). For the differential detection (to distinguish with UV-C absorption), we decorated the Ag nano-particles on the Nb 2 O 5 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.

Needle-like single crystalline wires of TaSe 3 were massively synthesized using the chemical vapor transport method. Since the wedged-shaped single TaSe 3 molecular chains were stacked along the b-axis by weak van der Waals interactions, a few layers of TaSe 3 flakes could be easily isolated using a typical mechanical exfoliation method. The exfoliated TaSe 3 flakes had an anisotropic planar structure, and the number of layers could be controlled by a repeated peeling process until a monolayer of TaSe 3 nanoribbon was obtained. Through atomic force and scanning Kelvin probe microscope analyses, it was found that the variation in the work function with the thickness of the TaSe 3 flakes was due to the interlayer screening effect. We believe that our results will not only help to add a novel quasi-1D block for nanoelectronics devices based on 2D van der Waals heterostructures, but also provide crucial information for designing proper contacts in device architecture.

A novel semiconductor 1D nanomaterial, Nb 2 Se 9 , was synthesized on a bulk scale via simple vapor transport reaction between niobium and selenium. Needle-like single crystal Nb 2 Se 9 contains numerous single Nb 2 Se 9 chains linked by van der Waals interactions, and we confirmed that a bundle of chains can be easily separated by mechanical cleavage. The exfoliated Nb 2 Se 9 flakes exhibit a quasi-two-dimensional layered structure, and the number of layers can be controlled using the repeated-peeling method. The work function varied depending on the thickness of the Nb 2 Se 9 flakes as determined by scanning Kelvin probe microscopy. Moreover, we first implemented a field effect transistor (FET) based on nanoscale Nb 2 Se 9 flakes and verified that it has p-type semiconductor characteristics. This novel 1D material can form a new family of 2D materials and is expected to play important roles in future nano-electronic devices., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Nb 2 O 5 nanostructures with excellent crystallinities were grown on c -plane sapphire and employed for ultraviolet-(UV)-radiation detection. The triangular radial Nb 2 O 5 grown on the c -sapphire substrate had a 6-fold symmetry with domain matching epitaxy on the substrate. Owing to the radial growth, the nanorods naturally connected when the deposition time increased. This structure can be used as a UV-detector directly by depositing macroscale electrodes without separation of a single nanorod and e-beam lithography process. It was confirmed that electric reactions occur at different UV irradiation wavelengths (254 nm and 365 nm)., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)