共查询到20条相似文献,搜索用时 31 毫秒
1.
采用弱配体柠檬酸钠修饰的金纳米花为介导材料,考察了其对人喉癌Hep-2细胞的NIR热疗作用,结果表明,这种金纳米花材料具有良好的NIR光热转换性能,可有效抑制Hep-2细胞增殖. 相似文献
2.
Binary carbon-supported platinum (Pt) nanoparticles were prepared by a chemical reduction method of Pt precursor on two types
of carbon materials such as carbon blacks (CBs) and graphite nanofibers (GNFs). Average sizes and loading levels of Pt metal
particles were dependent on a mixing ratio of two carbon materials. The highest electroactivity for methanol oxidation was
obtained by preparing the binary carbon supports consisting of GNFs and CBs with a weight ratio of 30:70. Furthermore, with
an increase of GNFs content from 0% to 30%, a charge-transfer resistance changed from 19 Ohm cm2 to 11 Ohm cm2. The change of electroactivity or the resistance of catalyst electrodes was attributed to the changes of specific surface
area and morphological changes of carbon-supported catalyst electrodes by controlling the mixing ratio of GNFs and CBs. 相似文献
3.
In this work, porous graphite nanofibers (GNFs) were prepared by a KOH activation method in order to manufacture porous carbon nanofibers. The process was conducted in the activation temperature range of 900-1100 degrees C, and the KOH:GNFs ratio was fixed at 3.5:1. The textural properties of the porous carbons were analyzed using N2 adsorption isotherms at 77 K. The BET, D-R, and BJH equations were used to observe the specific surface areas and the micro- and mesopore structures, respectively. From the results, it was found that the textural properties, including the specific surface area and the pore volumes, were proportionally enhanced with increasing activation temperatures. However, the activation mechanisms showed quite significant differences between the samples activated at low and high temperatures. 相似文献
4.
Synthesis of flower-like gold nanoparticles and their electrocatalytic activity towards the oxidation of methanol and the reduction of oxygen 总被引:1,自引:0,他引:1
This article describes the synthesis of branched flower-like gold (Au) nanocrystals and their electrocatalytic activity toward the oxidation of methanol and the reduction of oxygen. Gold nanoflowers (GNFs) were obtained by a one-pot synthesis using N-2-hydroxyethylpiperazine-N-2-ethanesulphonic acid (HEPES) as a reducing/stabilizing agent. The GNFs have been characterized by UV-visible spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), and electrochemical measurements. The UV-visible spectra show two bands corresponding to the transverse and longitudinal surface plasmon (SP) absorption at 532 and 720 nm, respectively, for the colloidal GNFs. The GNFs were self-assembled on a sol-gel-derived silicate network, which was preassembled on a polycrystalline Au electrode and used for electrocatalytic applications. The GNFs retain their morphology on the silicate network; the UV-visible diffuse reflectance spectra (DRS) of GNFs on the silicate network show longitudinal and transverse bands as in the case of colloidal GNFs. The GNFs show excellent electrocatalytic activity toward the oxidation of methanol and the reduction of oxygen. Oxidation of methanol in alkaline solution was observed at approximately 0.245 V, which is much less positive than that on an unmodified polycrystalline gold electrode. Reduction of oxygen to H2O2 and the further reduction of H2O2 to water in neutral pH were observed at less negative potentials on the GNFs electrode. The electrocatalytic activity of GNFs is significantly higher than that of the spherically shaped citrate-stabilized Au nanoparticles (SGNs). 相似文献
5.
Vapor-grown graphite nanofibers (GNFs) were modified by plasma treatments using low-pressure plasmas with different gases (Ar gas only and/or Ar/O2 gases), flow rates, pressures, and powers. Surface characterizations and morphologies of the GNFs after plasma treatment were investigated by X-ray photoelectron spectroscopy (XPS), contact angle, titration, and transmission electron microscopy (TEM) measurements. Also, the investigation of thermomechanical behavior and impact strengths of the GNFs/epoxy composites was performed by dynamic-mechanical thermal analysis (DMTA) and Izod impact testing, respectively. The plasma treatment of the fibers changed the surface morphologies by forming a layer with a thickness on the order of 1 nm, mainly consisting of oxygen functional groups such as hydroxyl, carbonyl, and carboxyl groups. After functionalization of the complete surfaces, further plasma treatment did not enhance the superficial oxygen content but slightly changed the portions of the functional groups. Also, the composites with plasma-treated GNFs showed an increase in T(g) and impact strength compared to the composites containing the same amount of plasma-untreated GNFs. 相似文献
6.
Guilhem Godeau Christophe Brun Hélène Arnion Cathy Staedel Philippe Barthélémy 《Tetrahedron letters》2010,51(7):1012-1015
The synthesis of two novel glycosyl-nucleoside fluorinated amphiphiles (GNFs) derived from the 2H,2H,3H,3H-perfluoro-undecanoyl hydrophobic chain is described. The GNF amphiphiles, which feature either β-d-glucopyranosyl or β-d-lactopyranosyl moieties linked to a thymine base via a 1,2,3 triazole linker, were prepared using a ‘double click’ chemistry route. Surface tension measurements, gelation properties, and TEM studies show that GNFs spontaneously assemble into supramolecular structures. Similarly to their hydrocarbon analogues (GNLs), the GNFs have unique gelation properties in water. A minimum hydrogelation concentration of 0.1% (w/w), was determined in the case of the β-d-glucopyranosyl derivative. Cell viability studies indicate that fluorocarbon GNF 5 was not toxic for human cells (Huh7), whereas hydrocarbon analogue GNL is toxic above 100 μm. 相似文献
7.
A simple method is described for the preparation of activated carbon fibers (ACFs) coated with graphite nanofibers (GNFs). Low-pressure-plasma mixed-gas (Ar/O2) treatment of the ACFs led to the growth of GNFs on their surface. The growth was greater at higher power inputs, and from TEM observations the GNFs were seen to be of herringbone type. It was found that the N2 adsorption capacity of the ACFs did not sharply decrease, and that volume resistivity of the ACFs enhanced as a result of this treatment. 相似文献
8.
In this work, graphite nanofibers (GNFs) were chemically activated for high specific surface area, small pore diameter, and
high oxygen-containing groups with different KOH/GNFs ratios and used as carbon supports of Pt–Ru nanoparticles for fuel cells.
As a result, the oxygen functional groups and specific surface area of carbon supports were increased with increasing the
ratios of KOH/GNFs up to 4:1, while the average of Pt–Ru nanoparticle size was decreased owing to the improvement of dispersibility
of the Pt–Ru/K–GNFs catalysts. The electrochemical activity of the Pt–Ru/K–GNFs catalysts was improved by the larger available
active surface area due to the increase of oxygen functional groups and specific surface area. Therefore, it was found that
chemical activation using KOH could influence the surface characteristic of carbon supports, resulting in enhanced electrochemical
activity of the Pt–Ru/K–GNFs catalysts of fuel cells. 相似文献
9.
In this work, the hydrogen storage behaviors of porous graphite nanofibers (GNFs) decorated by Pt nanoparticles were investigated. The Pt nanoparticles were introduced onto the GNF surfaces using a well-known chemical reduction method. We investigated the hydrogen storage capacity of the Pt-doped GNFs for the platinum content range of 1.3-7.5 mass%. The microstructure of the Pt/porous GNFs was characterized by X-ray diffraction and transmission electron microscopy. The hydrogen storage behaviors of the Pt/GNFs were studied using a PCT apparatus at 298 K and 10 MPa. It was found that amount of hydrogen stored increased with increasing Pt content to 3.4 mass%, and then decreased. This result indicates that the hydrogen storage capacity of porous carbons is based on both their metal content and dispersion rate. 相似文献
10.
Hsieh CK Tsai MC Yen MY Su CY Chen KF Ma CC Chen FR Tsai CH 《Physical chemistry chemical physics : PCCP》2012,14(12):4058-4061
We synthesized platelet graphitic-nanofibres (GNFs) directly onto FTO glass and applied this forest of platelet GNFs as a highly porous structural counter-electrode in dye-sensitized solar cells (DSSCs). We investigated the electrochemical properties of counter-electrodes made from the highly porous structural GNFs and the photoconversion performance of the cells made with these electrodes. 相似文献
11.
Kyohei Yoneda Prof. Masayoshi Nakano Hitoshi Fukui Takuya Minami Dr. Yasuteru Shigeta Prof. Dr. Takashi Kubo Dr. Edith Botek Prof. Dr. Benoît Champagne 《Chemphyschem》2011,12(9):1697-1707
The impact of topology on the open‐shell characters and the second hyperpolarizabilities (γ) has been addressed for one‐dimensional graphene nanoflakes (GNFs) composed of the smallest trigonal graphene (phenalenyl) units. The main results are: 1) These GNFs show not only diradical but also multiradical characters when increasing the number of linked units. 2) GNFs composed of an equivalent number of units can exhibit a wide range of open‐shell characters—from nearly closed‐shell to pure multiradical characters—depending on the linking pattern of the trigonal units. 3) This wide variation in open‐shell characters is explained by their resonance structures and/or by their (HOMO?i)?(LUMO+i) gaps deduced from the orbital correlations. 4) The change in the linking structure of the units can effectively control their open‐shell characters as well as their γ values, of which the longitudinal components are significantly enhanced for the singlet GNFs having intermediate open‐shell characters. 5) Singlet alternately linked (AL) systems present intermediate multiradical characters even in the case of a large number of units, which creates a significant enhancement of γ with increasing the size, whereas nonalternately linked (NAL) systems, which present pure multiradical characters, possess much smaller γ values. Finally 6) by switching from the singlet to the highest spin states, the γ values of NAL systems hardly change, whereas those of AL systems exhibit large reductions. These fascinating structure–property relationships between the topology of the GNFs, their open‐shell characters, and their γ values not only deepen the understanding of open‐shell characters of GNFs but aim also at stimulating further design studies to achieve giant NLO responses based on open‐shell graphene‐like materials. 相似文献
12.
Germanium oxide nanofilaments (GNFs) have been synthesized under ambient conditions from the gas phase using germanium tetrachloride as a precursor. Non-crystalline GNFs synthesized by this procedure are 1–10 μm in length and 80–110 nm in diameter applying Droplet Assisted Growth and Shaping (DAGS) Chemistry. The relative humidity has been adjusted at various values in order to demonstrate the crucial role of humidity in the gas phase for the nanofilament synthesis. The novel GNFs show a strong luminescence emission in the ultra-violet and light blue region. In addition, a self-cleaning and superhydrophobic properties could be introduced in the luminescent GNF nanofilaments by simple treatment with silane molecules. 相似文献
13.
《Journal of computational chemistry》2018,39(20):1387-1397
As nitrogen‐doped graphene has been widely applied in optoelectronic devices and catalytic reactions, in this work we have investigated where the nitrogen atoms tend to reside in the material and how they affect the electron density and spectroscopic properties from a theoretical point of view. DFT calculations on N‐doped hexagonal and rectangular graphene nanoflakes (GNFs) showed that nitrogen atoms locating on zigzag edges are obviously more stable than those on armchair edges or inside flakes, and interestingly, the N‐hydrogenated pyridine moiety could be preferable to pure pyridine moiety in large models. The UV–vis absorption spectra of these nitrogen‐doped GNFs display strong dependence on flake sizes, where the larger flakes have their major peaks in lower energy ranges. Moreover, the spectra exhibit different connections to various dopant types and positions: the graphitic‐type dopant species present large variety in absorption profiles, while the pyridinic‐type ones show extraordinary uniform stability and spectra independent of dopant positions/numbers and hence are hardly distinguishable from each other. © 2018 Wiley Periodicals, Inc. 相似文献
14.
Graphite nanofibers (GNFs), on which surface graphite edges were reconstructed into nano-loops, were explored as a cathode catalyst support for fuel cells. The high degree of graphitization, as well as the surface-reconstructed nano-loops that possess topological defects for uniform metal deposition, resulted in an improved performance of the GNF-supported Pt catalyst. 相似文献
15.
Promthong Niwat Tabtimsai Chanukorn Rakrai Wandee Wanno Banchob 《Structural chemistry》2020,31(6):2237-2247
Structural Chemistry - The adsorptions of CO and CO2 on pristine and transition metal-doped graphene nanoflakes (GNFs) were theoretically investigated using the density functional theory. Doping of... 相似文献
16.
MeiHuaYANG RongBinZHANG FengYiLI 《中国化学快报》2004,15(10):1230-1232
The NiB amorphous alloy catalysts supported on CNTs and alumina were prepared by impregnation and chemical reduction. The gas-phase benzene hydrogenation was used as a probe reaction to evaluate the catalytic activity. The result showed that the NiB amorphous alloy catalyst supported on carbon nanotubes exhibited higher activity than that supported on alumina. 相似文献
17.
Graphene nanoribbons with zigzag edges(ZGNRs) have attracted much attention for their spin-polarized edge states predicted more than 15 years ago. Since the ZGNRs are fabricated on metal substrates using molecular precursors, due to their strong coupling with metal substrates, experimental detection of the spin-polarized edge states is still difficult. Here, we design a partially hydrogenated graphene(PHGr), in which periodic hexagonal graphene nanoflakes(GNFs) with zigzag boundaries are embedded in a hydrogenated graphene layer. Using density functional theory(DFT) based first-principles calculations, we find that the hexagonal GNFs exhibit spin-polarized boundary states at their opposite zigzag boundaries, which is similar with the bow-tie-shaped GNFs and ZGNRs. DFT calculations demonstrate that the PHGr is a semiconductor with an antiferromagnetic ground state. Moreover, the antiferromagnetic boundary states and semiconduc-ting properties keep unchanged when the size of GNF varies from 1.4 nm to 2.3 nm. The robustness of the spin-polarized boundary states enables this PHGr as a robust material for detecting spin-polarized boundary states coming from zigzag boundaries. In addition, we find that single Au atoms selectively adsorbed on boundaries catalyze H2 dissociation and therefore lower the barrier of graphene hydrogenation. Therefore, the PHGr can be used not only in carbon-based spintronic devices but also as a platform for single atom catalyst. 相似文献
18.
Hsieh CK Tsai MC Su CY Wei SY Yen MY Ma CC Chen FR Tsai CH 《Chemical communications (Cambridge, England)》2011,47(41):11528-11530
We directly synthesized a platinum-nanoparticles/graphitic-nanofibers (PtNPs/GNFs) hybrid nanostructure on FTO glass. We applied this structure as a three-dimensional counter electrode in dye-sensitized solar cells (DSSCs), and investigated the cells' photoconversion performance. 相似文献
19.