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oe1(光电查) - 科学论文

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出版时间
  • 2018
研究主题
  • energy distribution
  • graphene edge
  • vacuum transistor
  • Field emission
应用领域
  • Optoelectronic Information Science and Engineering
机构单位
  • Naval Research Laboratory
  • KeyW Corporation
  • Pohang University of Science and Technology (POSTECH)
1443 条数据
?? 中文（中国） ▾

  • 2D Schottky Junction between Graphene Oxide and Transition-Metal Dichalcogenides: Photoresponsive Properties and Electrocatalytic Performance

    摘要： 2D graphene is conductor and not a semiconductor. 2D transition—metal dichalcogenides (TMD) is a semiconductor and not a conductor. Preparing 2D composite material that simultaneously possesses both advantages of graphene and TMD has proven to be challenging. In this work, both 2D-WS2/2D-GO and 2D-MoS2/2D-GO composites with few layer thickness are synthesized. The electronic structure indicates a high content of Mo4+ 3d5/2 and W4+4f7/2 with lower binding energy in the 2D composite, which is ascribed to partial loss of surface sulfur atoms in 2D composites and the newly formed heteroatomic bond of CWS and CMoS. The Schottky junction between 2D-GO and 2D-TMD (2D G-T junction) is established and exhibits obvious photoelectric responses. Superior electrocatalytic properties of the two 2D-composites are attributable to the 2D Schottky Junction between 2D-TMDs and 2D-GO. Interlayer electronic coupling in 2D Schottky Junction (2D G-T junction) activates inert sites on the 2D surface of 2D-TMDs or GO. The power conversion efficiency of dye-sensitized solar cells (DSCs) based on 2D-WS2/2D-GO is 9.54% under standard solar illumination intensity (AM1.5, 100 mW cm?2). The value is one of the highest reported efficiencies for DSCs based on Pt-free counter electrodes. Finally, 2D-WS2/2D-GO composites exhibit excellent stability as counter electrode of DSCs.

    关键词： photoresponse,interlayer electronic coupling,2D,electrocatalyst,graphene,transition-metal dichalcogenides,Schottky junction

    更新于2025-09-23 15:23:52

  • Ab Initio Design of Graphene Block Enables Ultrasensitivity, Multimeter-Like Range Switchable Pressure Sensor

    摘要： In pursuit of the next-generation pressure sensors, the fabrication of graphene-based devices is considered to be one of the most promising approaches to address the unsatisfied sensitivity within a wide pressure range. Here, an ab initio design based on the graphene block is proposed to realize a high-performance and multimeter-like range switchable pressure sensor. The sensor contains three designed graphene-based foams with different initial resistances, which enable continuous resistance-change behavior induced by the pressure. Specifically, the reduced graphene oxide (rGO) foam–based sensor demonstrates a three times resistance change within the pressure range of 0–300 Pa, the rGO/polyurethane (rGO/PU) foam–based sensor presents a six times resistance change within the pressure range of 0.09–30 kPa, and the selenium-functionalized rGO/PU (SFrGO/PU) foam–based sensor displays a resistance change of more than 1000-fold within the pressure range of 1–72 kPa. Such different initial resistances and responses endow the device with controllable estimating pressure ranges, offering a switchable multimeter-like function for various applications. This ab initio design, which is applicable to various 2D materials and operation modes, can provide a facile and feasible approach toward the next-generation pressure sensors and other application fields related to 2D materials.

    关键词： ultrahigh sensitivity,pressure sensor,graphene block,ab initio design,multimeter-like

    更新于2025-09-23 15:23:52

  • In-Situ covalent synthesis of gold nanorods on GO surface as ultrasensitive Raman probe

    摘要： In this paper, using thiolated graphene oxide (GO‐O‐SH) as substrate, gold nanorods (AuNRs) covalently linked to the GO surface by in‐situ seed growth method were first reported. The as‐prepared composites were characterized by UV–vis spectrum, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT‐IR). Experimental results indicated that the introduction of short flexible organic chain between GO and AuNRs contributed to the homogenous synthesis of gold rods, and uniform gold nanorods with aspect ratio within 3~8 were covalently linked to the surface of GO with high stability and yield. The strategy represented an outstanding improvement in comparison to the traditional route for fabricating the two GO@AuNRs composites. Furthermore, based on coupling of nanomaterials, the composites could act as high sensitive Raman probe with limit of detection (LOD) reaching 1 × 10?12 M.

    关键词： covalent synthesis,Raman probe,graphene oxide (GO),gold nanorods

    更新于2025-09-23 15:23:52

  • Raman analysis of strained graphene grown on dewetted cobalt

    摘要： Graphene grows onto cobalt by means of diffusion of carbon atoms during the isothermal stage of exposure to hydrocarbon precursor, followed by precipitation during cooling. This method, largely applied with nickel catalyst, is known to produce continuous, but not uniform, layers with the concurrent presence of mono‐ and poly‐graphene areas. With the aid of Raman mapping of graphene still lying onto its catalyst, we are able to consider the possible origins for the observed distortions of the phonon modes with respect to the well‐known picture of the monolayer material. Optical effects, doping, the presence of multi‐layered islands, and strain are kept into account. It is shown that some isotropic observations can be interpreted in terms of the occurrence of strain with the uniaxial component superimposed at the metal discontinuities. Strain is proposed to originate from the difference between the thermal expansion coefficients of graphene and cobalt. The present paper shows that inhomogeneities in graphene grown onto catalysts with high C solubility are not always directly related to excess of precipitation. The observation of strain in as‐grown graphene opens the possibility of tailoring the electronic density of states via strain engineering directly during growth.

    关键词： strain,graphene,micro‐Raman,cobalt,chemical vapor deposition

    更新于2025-09-23 15:23:52

  • Femtosecond Electron Dynamics in Graphene Nanoribbons - A Nonequilibrium Green Functions Approach Within an Extended Hubbard Model

    摘要： A new approach to study the correlated femtosecond electron dynamics in finite graphene clusters, such as nanoribbons, is presented here. The systems are described by an extended Hubbard model that takes into account the overlap of adjacent orbitals and hopping between up to third-nearest neighbors. The model is solved by the nonequilibrium Green functions approach combined with different self-energy approximations, including the second-Born and GW self-energy, to take into account electronic correlations. The description allows us to predict the correlated nonequilibrium dynamics of excited graphene nanostructures of arbitrary geometry containing up to 100 carbon atoms for up to 25 fs.

    关键词： correlated dynamics,nonequilibrium Green functions,Hubbard model,graphene nanoribbons

    更新于2025-09-23 15:23:52

  • Ultrasensitive LPFG corrosion sensor with Fe-C coating electroplated on a Gr/AgNW film

    摘要： This paper presents the first report on an ultrasensitive Fe-C coated long period fiber gratings (LPFG) corrosion sensor with graphene (Gr) and silver nanowire (AgNW) composite as a conductive film for Fe-C electroplating. The Gr/AgNW composite was grown on copper foil, wet transferred and adhered to the curve surface of the fiber optic sensor under atmospheric pressure and heating conditions. For comparison, another Fe-C coated LPFG sensor was prepared with silver nano ink as a conductive film. Both sensors were tested for 72 h in 3.5 wt.% NaCl solution with simultaneous measurements of transmission spectrum and electrochemical impedance spectroscopy. Due to its high optical transparency, the Gr/AgNW composite increased the wavelength sensitivity and service life of a Fe-C coated LPFG sensor by over 90% and 110%, respectively. The effective depth of influence to the evanescent field surrounding the LPFG sensor was 23.6 μm with the silver film and greater than 30 μm with the Gr/AgNW film.

    关键词： Long period fiber gratings,Silver nanowire,Corrosion sensor,Fe-C coating,Graphene

    更新于2025-09-23 15:23:52

  • Performance enhancement of ZnO nanorod-based enzymatic glucose sensor via reduced graphene oxide deposition and UV irradiation

    摘要： This paper reports the performance enhancement of a ZnO nanorod-based enzymatic glucose sensor with reduced graphene oxide (rGO) introduced between the ZnO nanorods and indium tin oxide (ITO) electrode and then stimulated under UV irradiation. The electrochemical characterization indicates that the rGO not only facilitates electron transfer through the ZnO nanorods to the ITO electrode but also inhibits the fast recombination of the photo-generated electrons and holes. The UV irradiation stimulates holes in the valence band of the ZnO nanorods, which as oxidants enhance the catalytic activity of the glucose oxidase (GOx) towards glucose. The rGO increases the sensitivity of the ZnO nanorod-based glucose sensor by 1.6 times and decreases the detection limit by 2.3 times. Together with the rGO, the UV irradiation further increases the sensitivity by 1.7 times and diminishes the detection limit by 2 times. Moreover, the as-prepared glucose sensors exhibit excellent selectivity to urea, uric acid, and ascorbic acid, and can reliably determine the glucose concentration in a serum sample. The results have the potential to improve the performance of other enzymatic biosensors.

    关键词： Glucose sensor,ZnO nanorod,UV irradiation,Graphene,Electrochemical test

    更新于2025-09-23 15:23:52

  • A cathodic photovoltammetric sensor for chloramphenicol based on BiOI and graphene nanocomposites

    摘要： A visible light-activated photocathode fabricated with p-type semiconductor bismuth oxyiodide (BiOI) and graphene (G) was employed to investigate the photovoltammetric behavior of chloramphenicol (CAP). The result indicated that the voltammetric reduction peak of CAP increased to a limiting current platform under photoirradiation, owing to photoelectrocatalytic reduction of CAP on the BiOI-G photocathode. As a result, the cathodic photovoltammogram became sigmoidal in shape. Furthermore, the influences of graphene content in BiOI-G composites, scan rate and light intensity on the photovoltammetric behavior of CAP on the BiOI-G photocathode were systematically investigated. Based on such a BiOI-G electrode, a cathodic photovoltammetric sensor for CAP was proposed, which exhibited a current response linearly proportional to CAP concentration in the range of 0.5 to 50 μmol L-1, with a detection limit (3S/N) of 0.14 μmol L-1. Moreover, the photovoltammetric sensor displayed good reproducibility and high stability. The applicability of the proposed sensor was demonstrated by determining CAP in eye drop and environmental water samples.

    关键词： Photovoltammetry,Photoelectrochemical sensor,Chloramphenicol,BiOI,Graphene

    更新于2025-09-23 15:23:52

  • UV Illumination-Enhanced Molecular Ammonia Detection Based On a Ternary-Reduced Graphene Oxide–Titanium Dioxide–Au Composite Film at Room Temperature

    摘要： In this work, we report on UV illumination enhanced room-temperature trace NH3 detection based on ternary composites of reduced graphene oxide nanosheets (rGO), titanium dioxide nanoparticles (TiO2) and Au nanoparticles as the sensing layer, which is firstly reported by far. The effect of UV state as well as componential combination and content on the sensing behavior disclosed that, rGO nanosheets served as not only a template to attach TiO2 and Au, but an effective electron collector and transporter; TiO2 nanoparticles acted as a dual UV and NH3 sensitive material; Au nanoparticles could increase the sorption sites and promote charge separation of photoinduced electron-hole pairs. The as-prepared rGO/TiO2/Au sensors were endowed with a sensing response of 8.9% toward 2 ppm NH3, a sensitivity of 1.43×10-2/ppm within the investigated range, nice selectivity, robust operation repeatability and stability, which was fairly competitive in comparison with previous work. Meanwhile, the experimental results provided clear evidence of inspiring UV-enhanced gas detection catering for the future demand of low power-consumption and high sensitivity.

    关键词： Room temperature.,Gas sensor,Reduce graphene oxide,Ammonia,Au nanoparticle,Titanium dioxide,UV illumination

    更新于2025-09-23 15:23:52

  • On the Double Nano-Coned Graphite Metasurface-Based Multiband CIC Absorber

    摘要： Spectral characteristics of nano-engineered absorber comprised of nano-cone-shaped multi-layered (or cascaded) graphene metasurface (that results in graphite medium) were investigated under different chemical potentials and incidence conditions. The configuration of the proposed absorber is of the conductor-insulator-conductor (CIC) kind, wherein the top and bottom metasurfaces are identical in a pattern having the array of graphite-cones. Such three-layer CIC absorber hosts relatively thick dielectric substrate sandwiched between graphite nano-cone-based metasurfaces, in order to trap incidence electromagnetic fields. The results in respect of absorbance revealed usefulness of the proposed structure in spectral filtering in the visible and far-infrared regimes. Also, the tuning feature of absorber through altering the chemical potential of metasurfaces was highlighted.

    关键词： Nano-engineered mediums,Complex mediums,Metamaterial absorbers,Graphene structures

    更新于2025-09-23 15:23:52