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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） ▾

  • Resonance Tunneling Phenomena in Two-Dimensional Multilayer van der Waals Crystalline Systems

    摘要： Works, mostly experimental, concerning the most interesting features of application of the resonant tunneling spectroscopy to a new type of heterosystems, van der Waals heterostructures, have been briefly reviewed. These heterostructures appeared after the recent discovery of two-dimensional crystals, which are a new class of materials beginning with graphene. The role of the angular matching of crystal lattices of conducting graphene electrodes of van der Waals systems in carrier tunneling between them has been analyzed together with the closely related problems of satisfaction of conservation laws in tunneling transitions. Manifestations of multiparticle correlation interactions between carriers in van der Waals systems such as Wigner crystallization of electrons in a two-dimensional electron gas in a magnetic field and Bose condensation of excitons in parallel two-dimensional electron gases have been briefly discussed.

    关键词： angular matching,momentum conservation,resonant tunneling spectroscopy,graphene,two-dimensional crystals,Wigner crystallization,van der Waals heterostructures,Bose condensation

    更新于2025-09-23 15:23:52

  • Sensitivity enhancement of surface plasmon resonance sensor with 2D material covered noble and magnetic material (Ni)

    摘要： In this paper, surface plasmon resonance (SPR) sensor on 2D materials such as MoS2 and graphene on Au and magnetic material Ni in Kretschmann configuration is analyzed using transfer matrix method. Here we noted that by sandwiching the MoS2 layer between the Au and Ni film and adding graphene over Ni film improved the sensitivity as high as 229°/RIU. We also noted that the sensitivity of the proposed sensor changes with the addition of no. of layers of graphene and MoS2. We expect that such a high sensitivity SPR sensor could find optional application in chemical examination, medical diagnostic and biological detections.

    关键词： MoS2,Biosensor,Graphene,Sensitivity,Surface plasmon resonance

    更新于2025-09-23 15:23:52

  • Ultra-sensitive surface plasmon resonance biosensor based on MoS2–graphene hybrid nanostructure with silver metal layer

    摘要： The optical biosensors based on the plasmonic technology are an important research item in the field of biophotonics. The graphene–molybdenum disulfide (MoS2) based hybrid structures are very effective in designing and fabricating of the sensitive optical biosensors. In this paper, we propose a nanostructure Ag/MoS2/graphene as an optical biosensor with high performance and sensitivity. The proposed configuration for this surface plasmon resonance (SPR) optical biosensor is Kretschmann. Herein, the enhancement of sensitivity for the proposed SPR optical biosensor is investigated in different states. By determining of the numbers of MoS2 layer and the thickness of the metal layer, we increased the sensitivity of the proposed biosensor. The maximum sensitivity ~ 190°/RIU is achieved. For this ultra-sensitive SPR biosensor with maximum sensitivity, the numbers of MoS2 and graphene layer is 2 and the resonance wavelength is determined 680 nm.

    关键词： Surface plasmon resonance,Molybdenum disulfide,Biosensor,Sensitivity,Graphene

    更新于2025-09-23 15:23:52

  • Graphene oxide-based zirconium oxide nanocomposite for enhanced visible light-driven photocatalytic activity

    摘要： In the present investigation, an efficient visible light-active, graphene oxide-based zirconium oxide nanocomposite (GO–ZrO2) has been synthesized by co-precipitation method. The synthesized photocatalyst was characterized by XRD, FTIR, FE-SEM, EDS, TEM, TGA, PL, UV-DRS and BET surface area analysis. The characterization results illustrate the homogeneous dispersion of ZrO2 nanoparticles in the GO–ZrO2 nanocomposite with excellent harmony between GO and ZrO2 nanoparticles. The photocatalytic efficiency of the synthesized GO–ZrO2 nanocomposite was evaluated by photodegradation of hazardous, water-soluble rhodamine B and methylene blue dyes under visible light irradiation. The 90% photocatalytic degradation of rhodamine B dye (with initial conc. 30 mg/L) was observed in 105 min of visible light irradiation, while 99.23% of methylene blue (with initial conc. 100 mg/L) dyes degradation was observed in just 60 min using 25 mg/100 ml dose of GO–ZrO2 nanocomposite as a photocatalyst. The mechanistic investigation using scavengers suggest that the superoxide (O2·?) is the most reactive species involved in the photodegradation of organic dyes. The synthesized photocatalyst GO–ZrO2 nanocomposite also exhibits excellent thermal stability and reusability.

    关键词： Methylene blue,Rhodamine B,Photocatalytic activity,Zirconium oxide,Graphene oxide,Visible light,Co-precipitation method

    更新于2025-09-23 15:23:52

  • B-Doping-Enhanced Stability of Phosphorene/Graphene Heterostructures

    摘要： Two-dimensional material heterostructures show large surface area and unusual electronic properties, being used in nanoelectronic devices, energy storage devices, and sensors. Doping can improve stability of the heterostructures. Structural and electronic properties of B–doped phosphorene/graphene heterostructures are studied using ?rst-principles calculations. B doping in phosphorene enhances the interlayer charge transfer from phosphorene to graphene. Importantly, B doping creates strong chemical bonding at the interface, which improves stability of phosphorene/graphene heterostructures. The band gap is opened up to 0.53 eV by B doping.

    关键词： heterostructure,DFT calculations,graphene,phosphorene,chemical bonding

    更新于2025-09-23 15:23:52

  • Continuous Photocatalysis Based on Layer-by-layer Assembly of Separation-free TiO?/Reduced Graphene Oxide Film Catalysts with Increased Charge Transfer and Active-site

    摘要： Although photodegradation is the most widely studied method for the purification of water, the challenges for the post-separation of catalysts from water prevent the technique from practical applications. In this study, separation-free TiO2/reduced graphene oxide (rGO) multilayer films were first prepared through layer-by-layer (LbL) assembly of TiO2 and graphene oxide (GO) on quartz slides, followed by a reduction of the assembled GO to rGO. For a proof-of-concept demonstration of novel continuous photocatalysis with potential for scale-up production, these quartz slides with TiO2/rGO film catalysts were further assembled into slide arrays in a home-made rectangular quartz reactor and a model pollutant Rhodamine B (RhB) solution was circularly pumped over the slide surface under UV irradiation. It was found that the as-prepared TiO2/rGO film catalysts show excellent enhanced continuous photocatalytic activity, with a photodegradation rate constant of 2.6 × 10-2 min?1 exceeding the corresponding TiO2/GO and TiO2 (TiO2/PSS) samples by a factor of 11.3 and 13, respectively. The enhanced performance is attributed to the formation of Ti-O-C bonds in film catalysts bridging TiO2 and rGO to enable efficient charge separation and transfer, the Ti-O-C bond bridged electron transfer leading to increase in ·O2- active sites on the rGO surface, and the porous-like multilayer structure. The recycling experiments showed the film catalysts are stable and could be reused with the same efficiency for at least 8 cycles.

    关键词： layer-by-layer,continuous photocatalysis,separation free,graphene,film

    更新于2025-09-23 15:23:52

  • Enhanced photocatalytic activity of TiO2/graphene by tailoring oxidation degrees of graphene oxide for gaseous mercury removal

    摘要： We used a simple method of graphene oxide (GO) preparation with different oxidation levels, and control the properties of the TiO2 nanocrystals by tuning the content and oxidation degree of GO to enhance the photocatalytic performance. During the hydrothermal reaction, reduction of GO, formation of TiO2 and chemical bonds between TiO2 and reduced graphene oxide (RGO) was achieved simultaneously. Characterization results showed that TiO2 properties such as crystalline grain and particle size could be tailored by the amount of functional groups, and that crystallinity was also controlled by GO degrees of oxidation. TiO2/RGO photocatalysts showed great efficiency of mercury oxidation, which reached 83.7% and 43.6% under UV and LED light irradiation, respectively. The effects of crystalline grain size and surface chemical properties on Hg0 removal under LED and UV light irradiation were analyzed. In addition, the properties of the photocatalysts before and after UV illumination were investigated, finding that part of Ti-OH on TiO2 surface transformed to Ti-O-Ti. In a nutshell, this work could provide a new insight into enhancing activity of photocatalysts and understanding the photocatalytic mechanism.

    关键词： TiO2,Photocatalysis,Chemical Bonds,Elemental Mercury,Reduced Graphene Oxide

    更新于2025-09-23 15:23:52

  • Silver nanoparticles with reduced graphene oxide for surface-enhanced vibrational spectroscopy of DNA constituents

    摘要： Composite of silver nanoparticles with reduced graphene oxide flakes is proposed for surface enhanced vibrational spectroscopy, particularly for detection of adenine and thymine as constituents of deoxyribonucleic acid. Composite was formed by original method implying simultaneous reduction of silver ions and graphene oxide by discharge plasma at the gas–liquid interface. Combination of nanosized silver with reduced graphene oxide provided greater enhancement of Raman light scattering and infrared light absorption in comparison with separately used components. Addition of the composite to water solutions of adenine and thymine allowed detection of these analytes at micromolar concentrations. Composite of nano-silver with reduced graphene oxide can be prospective for surface enhanced spectroscopy as an alternative to the expensive lithographically prepared noble metal substrates.

    关键词： Adenine,Surface Enhanced InfraRed Absorption (SEIRA),Thymine,Reduced graphene oxide,Discharge plasma,Silver nanoparticles,Surface Enhanced Raman Scattering (SERS)

    更新于2025-09-23 15:23:52

  • The study of Fe-doped CdS nanoparticle-assisted photocatalytic degradation of organic dye in wastewater

    摘要： Size-tunable nanoparticles (NPs) for pristine cadmium sulfide (CdS) and iron (Fe)-doped (5, 10 and 15%) CdS were synthesized using facile chemical co-precipitation. Size-controlled NPs were prepared with thioglycolic acid (TGA) as the capping agent and their structural, optical, morphological and physiochemical evaluations were performed using X-ray diffraction (XRD), UV–visible spectroscopy, Raman spectroscopy, field emission scanning electron microscopy (FESEM) and Fourier transform infrared (FTIR). XRD revealed single cubic phase of CdS and later broader peaks upon mixing of Fe, and intensive absorption was recorded in the visible regime upon doping with redshift. FESEM confirmed spherical nanoparticles of Fe–CdS, and Cd–S linkage along with other functional groups was recognized by FTIR. Cd1?xFexS (x = 0, 0.05, 0.10 and 0.15) powder was used as the photocatalyst for methylene blue (MB) degradation in visible light and catalyst in NaBH4’s presence. The control CdS bleached MB faster than doped but doped CdS showed higher catalytic degradation. The Fe-doped CdS NPs showed superior catalytic potential compared to undoped CdS which suggests their use in dye industries, especially leather and tanneries. Additionally, NPs not only show superior catalytic characteristics but also help in cost reduction and complete removal of dyes for wastewater management.

    关键词： Metal oxide,Photocatalytic activity,XRD,Graphene,Sol–gel

    更新于2025-09-23 15:23:52

  • Epitaxial Graphene Sensors Combined with 3D Printed Microfluidic Chip for Heavy Metals Detection

    摘要： Two-dimensional materials may constitute key elements in the development of a sensing platform where extremely high sensitivity is required, since even minimal chemical interaction can generate appreciable changes in the electronic state of the material. In this work, we investigate the sensing performance of epitaxial graphene on Si-face 4H-SiC (EG/SiC) for liquid-phase detection of heavy metals (e.g., Pb). The integration of preparatory steps needed for sample conditioning is included in the sensing platform, exploiting fast prototyping using a 3D printer, which allows direct fabrication of a microfluidic chip incorporating all the features required to connect and execute the Lab-on-chip (LOC) functions. It is demonstrated that interaction of Pb2+ ions in water-based solutions with the EG enhances its conductivity exhibiting a Langmuir correlation between signal and Pb2+ concentration. Several concentrations of Pb2+ solutions ranging from 125 nM to 500 μM were analyzed showing good stability and reproducibility over time.

    关键词： heavy metals detection,3D printed flow cell,reusable lab-on-chip,epitaxial graphene,high sensitivity

    更新于2025-09-23 15:23:52