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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） ▾

  • Optical properties of amine-functionalized graphene oxide

    摘要： Important applications of graphene oxide (GO) its derivatives have been found in several areas: energy materials, water treatment, environmental, catalytic, photocatalytic, and biomedical technologies. Among them, the application of GO in optical biosensors has attracted ever-increasing interest in the past few years. In the present work, GO was amine-functionalized by a solvent-free one-step method with two aromatic amines: 1-aminopyrene (AP), and 2-aminofluorene (AF); and one aliphatic amine 1-octadecylamine (ODA). Particle size was estimated by field emission-scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). Optical properties have been evaluated by application of photoluminescence (PL), FTIR, UV–VIS, and Raman spectroscopy. As a result, this study offers an efficient way to tune the optical properties due to their amine functionalization, favoring the development of optoelectronic and biological applications using graphene-based materials in the future.

    关键词： Amine functionalization,Optical properties,Sensors,Graphene oxide

    更新于2025-09-23 15:23:52

  • Q-graphene-scaffolded covalent organic frameworks as fluorescent probes and sorbents for the fluorimetry and removal of copper ions

    摘要： Metal-free fluorescent covalent organic frameworks (COFs) were synthesized initially with Q-Graphene (QG) scaffolds by the one-step covalent reactions of melamine-aldehyde and phenol-aldehyde poly-condensations using paraformaldehyde. It was discovered that onion-like hollow QG, which consists of multi-layer graphene and different carbon allotropes having a high proportion of folded edges and surface defects, could endow the scaffolded COFs with enhanced green fluorescence and environmental stability. Unexpectedly, they could exhibit the powerful absorption for Cu2+ ions resulting in the specific quenching of fluorescence. A fluorimetric strategy with QG-scaffolded COFs was thereby developed to probe Cu2+ ions separately in blood and wastewater with the linear concentration ranges of 0.0010 - 10.0 μM (limit of detection of 0.50 nM) and 0.0032 - 32.0 μM (limit of detection of 2.4 nM), respectively, promising the potential applications for the field-applicable monitoring of Cu2+ ions in the clinical and environmental analysis fields. In addition, the prepared COFs sorbents were employed to absorb Cu2+ ions in wastewater showing high removal efficiency. More importantly, such an one-pot fabrication route with hollow QG scaffolds may be tailorable extensively for the preparation of a variety of metal-free multifunctional COFs with enhanced fluorescence, water solubility, environmental stability, and metal removal capability.

    关键词： Q-Graphene Scaffold；Covalent Organic Frameworks；Fluorescent Analysis；Removal Sorbents；Copper Ions

    更新于2025-09-23 15:23:52

  • Millimeter-Scale Growth of Single-Oriented Graphene on a Palladium Silicide Amorphous Film

    摘要： It is widely accepted in condensed matter physics and material science communities that a single-oriented overlayer cannot be grown on an amorphous substrate because the disordered substrate randomizes the orientation of the seeds, leading to polycrystalline grains. In the case of two-dimensional materials such as graphene, the large-scale growth of single-oriented materials on an amorphous substrate has remained unsolved. Here, we demonstrate experimentally that the presence of uniformly oriented graphene seeds facilitates the growth of millimeter-scale single-oriented graphene with 3×4 mm2 on palladium silicide, which is an amorphous thin film, where the uniformly oriented graphene seeds were epitaxially grown. The amorphous palladium silicide film promotes the growth of the single-oriented growth of graphene by causing carbon atoms to be diffusive and mobile within and on the substrate. In contrast to these results, without the uniformly oriented seeds, the amorphous substrate leads to the growth of polycrystalline graphene grains. This millimeter-scale single-oriented growth from uniformly oriented seeds can be applied to other amorphous substrates.

    关键词： silicon carbide,amorphous substrate,single orientation,graphene,palladium silicide

    更新于2025-09-23 15:23:52

  • Exploiting electrostatic shielding-effect of metal nanoparticles to recognize uncharged small molecule affinity with label-free graphene electronic biosensor

    摘要： Label-free electronic biosensors as the non-electrochemical analytical tools without requirement of sophisticated instrumentation have become attractive, although their application in competitive affinity sensing of uncharged small molecules is hindered by a difficulty in the development of competing analogues. To break through this bottleneck, we report a novel analogue made by epitope-modified metal nanoparticles to enable the electronic signaling of small-molecule analyte recognition via competitive affinity. While the electronic signaling capability of metal nanoparticle analogues is demonstrated by a graphene field-effect transistor bioassay of small-molecule glucose as a proof-of-principle, interestingly, we discover a new electronic signaling mechanism in the metal nanoparticle affinity, different to the intuitive charge accumulation expectation. On the basis of Kelvin-probe force microscopic potential characterization and theoretical discussion, we fundamentally elucidated the signaling mechanism as a seldom used electrostatic shielding-effect, that is, in the analogue-receptor affinity, metal nanoparticles with the charge density lower than receptor biomolecules can reduce the collective electrical potential via charge dispersion. Further consider the convenient epitope-modifiability of metal nanoparticles, the easy-to-develop analogues for diverse target analyte might potentially be predictable in the future. And the application of label-free electronic biosensors for the competitive affinity bioassay of range-extended small molecules may thus be promoted based on the electrostatic shielding-effect.

    关键词： electrostatic shielding-effect,competitive affinity,graphene field-effect transistor biosensor,uncharged small molecule,metal nanoparticle analogue

    更新于2025-09-23 15:23:52

  • Ultrasound-Assisted Nitrogen and Boron Co-doping of Graphene Oxide for Efficient Oxygen Reduction Reaction

    摘要： Development of naturally abundant, low cost, and energy-efficient electrocatalysts for the oxygen reduction reaction (ORR) is essential for commercialization of fuel cells. In this work, we report simple ultrasonication assisted synthesis of nitrogen and boron dual-doped graphene oxide (NB/GO) and demonstrate its application as an effective ORR catalyst realizing predominantly 4e? reduction of O2 to OH? in 0.1 M KOH. Enhanced ORR electrocatalysis of the dual B and N co-doped GO as opposed to GO singly doped with B or N arises from the synergistic interaction of the boron and nitrogen species. The content and configuration of both N and B dopants can be readily tailored by controlling the ultrasonic conditions, thereby permitting tuning of the ORR activity. Furthermore, the developed NB/GO metal-free catalyst exhibited very promising long-term durability and resistance to methanol poisoning compared to the state of the art Pt/C catalyst.

    关键词： Oxygen reduction reaction,Graphene,Doping,Electrocatalysis

    更新于2025-09-23 15:23:52

  • Abrupt changes in the graphene on Ge(001) system at the onset of surface melting

    摘要： By combining scanning probe microscopy with Raman and x-ray photoelectron spectroscopies, we investigate the evolution of CVD-grown graphene/Ge(001) as a function of the deposition temperature in close proximity to the Ge melting point, highlighting an abrupt change of the graphene’s quality, morphology, electronic properties and growth mode at 930 °C. We attribute this discontinuity to the incomplete surface melting of the Ge substrate and show how incomplete melting explains a variety of diverse and long-debated peculiar features of the graphene/Ge(001), including the characteristic nanostructuring of the Ge substrate induced by graphene overgrowth. We find that the quasi-liquid Ge layer formed close to 930 °C is fundamental to obtain high-quality graphene, while a temperature decrease of 10 degrees already results in a wrinkled and defective graphene film.

    关键词： Chemical Vapor Deposition,Germanium,Scanning Tunneling Microscopy,Catalysis,Graphene

    更新于2025-09-23 15:23:52

  • Optimizing P25-rGO composites for pesticides degradation: Elucidation of photo-mechanism

    摘要： The junction of graphene oxide with TiO2 particles can help develop more efficient photocatalysts capable to harvest radiation in a wider range of the electromagnetic spectrum for real photocatalytic applications. The synthesis procedure of TiO2 P25-rGO composites was optimized to photodegrade a selected mixture of pesticides classified by EU as priority pollutants (alachlor, diuron, atrazine and isoproturon). The influence of temperature and time of hydrothermal method, as well as the effect of graphene oxide (GO) percentage added in the synthesis, was studied to obtain the nanocomposite that showed the highest photoactivity. Long time and moderate temperature have offered the best interaction between TiO2 P25 and rGO. GO was quantitatively reduced to rGO during the hydrothermal treatment, but maintains a higher level of disorder. The optimal GO loading was found around 0.25 wt. %, which allowed the photocatalyst achieve high photocatalytic performance both in phenol and pesticides photodegradation. Finally, in order to try to elucidate the photocatalytic mechanism of the selected mixture of pesticides three scavengers were employed: methanol to scavenge hydroxyl radicals, formic acid for the photogenerated holes, and copper (II) nitrate to quench the electrons of the conduction band. In conclusion, all these pesticides were mostly photodegraded by the hydroxyl radicals (HO?) produced from the photo-induced holes (h+); given that the oxidant species generated from electrons or mediated by direct mechanism were not relevant.

    关键词： Scavengers,TiO2P25-reduced graphene oxide composites,Pesticides,Photo-mechanism

    更新于2025-09-23 15:23:52

  • Mitigating the electromagnetic radiation by coupling use of waste cathode-ray tube glass and graphene oxide on cement composites

    摘要： With technological development, the rapid growing numbers of electronic devices generate severe electromagnetic interference (EMI) and radiation to human environment. In this study, the coupling effect of graphene oxide (GO) addition (up to 0.10 wt.% of cement) and waste cathode-ray tube (CRT) glass replacement for fine aggregates (30 and 60 wt.%) in cement-based composites on mitigating EMI was studied. The electric permittivity obtained using a decoupling method was applied for evaluating the EMI shielding capacity of cement-based composites, while direct current (DC) electrical resistance measurement is conducted using four-probe method. The DC electrical resistivity of specimens increases insignificantly with increasing in GO content, but remarkably with increasing CRT glass content from 30 to 60 wt.%. The 60 wt.% replacement of waste CRT glass with 0.1 wt.% GO addition increases the relative permittivity by about 50% and 200% when the frequency is in the ranges of 104–5 × 106 Hz and 101–103 Hz, respectively. It is concluded that a significant increase in the permittivity can be obtained owing to the synergetic interaction between waste CRT glass and GO. The improvement in the EMI shielding ability of cement-based composites not only enables the applications of these composites in mitigating electromagnetic pollution, but also promotes large-volume recycling of toxic waste CRT glass.

    关键词： Permittivity,Waste CRT glass,Cement composite,Graphene oxide,Electromagnetic interference

    更新于2025-09-23 15:23:52

  • 2D reentrant micro-honeycomb structure of graphene-CNT in polyurethane: High stretchability, superior electrical/thermal conductivity, and improved shape memory properties

    摘要： The recent rapid development of soft electronics and wearable technology has demanded materials with the function of combining mechanical deformation and electronics. Particularly, materials simultaneously having memory shape characteristics in which mechanical deformation repeatedly occurs in response to stimulus, high stretchability and excellent electric/heat transfer characteristics are interesting actuator materials in future applications. As a stretchable and conductive platform, we fabricated a reentrant micro-honeycomb structure from graphene-CNT, which had structural stretchability due to the accordion-like reentrant structure and continuous conductive paths in the vertical and horizontal directions. To impart shape memory properties, we fabricated composites by simply infiltrating shape memory polyurethane (SMPU) into a stable graphene/CNT framework. Our resulting reentrant micro-honeycomb graphene-CNT/SMPU composites simultaneously exhibited a relatively low resistivity of 5 Ω cm, a change in resistance of less than 10% in the 50% stretching/releasing states, long term stability, and superior tensile shape memory properties, including 95.6% shape fixity and a 90.6% recovery ratio. Regularly distributed graphene-CNT structures offer heterogeneous nucleation sites and undisturbed crystal growth in neat SMPU pillars, resulting in superior shape memory properties. We also constructed a circuit with portable batteries to demonstrate that our reentrant graphene-CNT/SMPU composite offers potential applications as an emergency circuit breaker.

    关键词： Shape memory,Polyurethane,Reentrant graphene-CNT,Composite,Ice-templated self-assembly

    更新于2025-09-23 15:23:52

  • Gamma irradiated poly (methyl methacrylate)-reduced graphene oxide composite thin films for multifunctional applications

    摘要： Poly (methyl methacrylate) (PMMA)-Reduced Graphene Oxide (rGO) (PrGO) composite films were fabricated by solvent evaporation technique and exposed to gamma radiation at different dosages viz. 25 kGy, 50 kGy and 100 kGy. The XRD analysis revealed the phases of PMMA and rGO and further confirmed the semi-crystalline nature of PMMA. The irradiation also decreased the peak intensities of the functional groups of PMMA and rGO. At 50 kGy irradiation, lamellar structures were formed on the surface of the films (50 kGy) due to the thermal fluctuations whereas, at higher dosage (100 kGy), pores were formed. The surface roughness and contact angle were enhanced on 50 kGy sample. The drug impregnated PrGO50 and PrGO100 samples showed sustained and burst release of drug respectively and in addition exhibited a better zone of inhibition against E. coli bacteria. All the samples were hemocompatible in nature. Fibroblast proliferation was enhanced with no cytotoxic effect on 50 kGy samples. Hence, the gamma irradiated samples could be an excellent candidate for biosensing and biomedical applications.

    关键词： Biomedical Applications,Polymer,Bioactive,Reduced-graphene oxide composites

    更新于2025-09-23 15:23:52