共查询到19条相似文献,搜索用时 62 毫秒
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分别选取阴离子型、阳离子型和非离子型3种类型表面活性剂,通过紫外可见光谱研究表面活性剂结构和浓度对高压均质-液相剥离法制备的石墨烯水分散液浓度的影响。通过高分辨透射电镜和激光粒度仪对所制备的石墨烯的品质进行分析。结果表明:长的疏水链段、双键和苯环官能团是促进表面活性剂作用发挥的关键结构,表面活性剂最优浓度略高于其临界胶束浓度。在测试范围内,Tween80效果最佳,其最佳作用浓度为0.012mmol·L^-1,所得石墨烯水分散液浓度为564.3mg·L^-1。表面活性剂的结构和浓度对石墨烯的品质无明显影响。 相似文献
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本研究将兼具自组装膜和石墨烯两者优点的复合材料作用于基底,讨论了具有特殊电化学性能的自组装膜-石墨烯电化学界面信号检测系统。同时,通过对自组装膜-石墨烯构建的以石墨烯为基础的FET(GFETs)结构特性的分析,发现以自组装膜功能化的石墨烯可以提供有效的方式调控其性质,减少界面的不纯散射及滞后的场效应行为。文章还探讨了自组装膜-石墨烯在染料敏化太阳能电池及p-n结领域中的研究与应用,对有机分子自组装膜-石墨烯复合材料在控制界面电子性质的应用前景进行了展望。 相似文献
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利用高压均质液相剥离法,以鳞片石墨为原料,水为介质,制备高浓度石墨烯水分散液。采用紫外可见光谱研究表明活性剂浓度、高压均质压力和循环次数对石墨烯水分散液浓度C_G的影响。通过拉曼光谱、扫描电镜、透射电镜、激光粒度仪分析水分散液中石墨烯的结构和形貌。结果表明:通过调节各工艺参数,获得了浓度为324.3mg·L-1的石墨烯水分散液,所得浓度是超声液相剥离法的10倍;石墨烯水分散液中石墨烯缺陷少、厚度薄、片径大,具有良好的品质;将所得石墨烯分散液制备石墨烯自支撑膜,其电导率可达3.2×10~4S·m-1。 相似文献
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将氧化石墨烯(GO)添加到聚丙烯酸(PAA)溶液中,并与聚乙烯亚胺(PEI)在阳离子交换膜表面通过层层自组装(LBL)法制备了单价选择性离子交换膜。结果表明,PEI为表层的复合膜,具有更高的单价离子选择性,随着层层自组装的进行,GO连续地沉积到膜的表面。复合膜的面电阻随组装层数的增加而增大,相比于未添加GO的多层膜,GO的加入有利于膜电阻的降低。同时,随着自组装层数的增加,复合膜的单价离子分离效率提高;GO浓度升高,复合膜的单价离子选择性先升高后降低,当GO浓度升高至0.5 g/L时,复合膜的分离效率最高。 相似文献
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石墨烯因具有制备方法简单、比表面积大以及生物共溶性好等优点,很多研究者将其应用于生物领域。在本工作中,我们以高比表面积的三维石墨烯作为载体,通过尝试不同的方法对其表面进行改性,然后负载银纳米粒子,制备出纳米银/石墨烯复合纳米材料。通过SEM,TEM以及Zeta电位仪进行一系列的表征和跟踪分析,摸索出制备银/石墨烯复合材料的最佳条件。该复合材料在抗菌领域具有广泛的应用前景。 相似文献
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Graphene-based composites are appealing as a new class of materials that hold great promise for many applications. In this paper, highly ordered, homogeneous graphene oxide-poly(vinyl alcohol) (GO-PVA) with different content of PVA membranes and reduced graphene oxide-poly(vinyl alcohol) (RGO-PVA) membrane at 75% loading of PVA in the presence of hydrazine hydrate solution are prepared by the self-assemble process at liquid/air interface. The as-prepared membranes were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), transmission electron microscopy (TEM), Ultraviolet-visible (UV-vis) spectroscopy and four-probe resistance measurements. It was shown that the free-standing GO-PVA and RGO-PVA membranes are thickness controlled and area adjustable. The GO-PVA membranes have excellent transparent. The electrical conductivity of RGO-PVA membranes was up to 0.6 S/m by the chemical reduction of hydrazine hydrate. The membranes would be promising for practical applications in future nanotechnology. 相似文献
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In this letter, we report the dielectric/graphene interface physics and engineering of large-scale, chemical vapor deposited (CVD) graphene transistors by self-assembling a molecular-scale organosilane monolayer onto the dielectric surface. We show that phenyl-alkyl-terminated self-assembled monolayers (SAM) at the dielectric/graphene interface consistently improve the graphene device performance and reliability. The extrinsic field-effect mobility of large-scale CVD graphene transistors on the phenyl-SAM engineered dielectric is currently up to 2500 cm(2)/(V s) at room temperature, considerably higher than the counterparts without the SAM. In addition, significant reduction on the bias stress instability and hysteresis is achieved by the SAM-based interface engineering. Further analysis reveals that charge injection from graphene to the dielectric/graphene interface dominates the observed hysteresis behavior. For both graphene transistors with and without SAMs, the bias stress stability, that is, Dirac point shift under bias stress, is well described by the stretched exponential model with its fitting parameters clearly indicating different interface properties. 相似文献
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Here we report the first observation of hyper-Rayleigh light scattering from bacteriorhodopsin in the form of an aqueous suspension of unoriented purple membranes. A typical purple membrane suspension used in our experiments contains approximately 10(8) randomly oriented purple membranes. Each purple membrane contains approximately 10(5) bacteriorhodopsin molecules in a two-dimensional crystallinearray. Hyper-Rayleigh light scattering is observed when the purple membrane suspension is illuminated with light that has a wavelength of 1064 nm. We propose that the 532-nm scattered light from each of the bacteriorhodopsin molecules in a single purple membrane is coherent, and that the scattered light from different purple membranes is incoherent. This proposal is supported by the following experimental observations: (a) the 532-nm light intensity is proportional to the square of the incident power, (b) the intensity of the 532-nm signal is linearly proportional to the concentration of purple membrane in solution, (c) the scattered 532-nm light is incoherent, (d) the scattered 532-nm light intensity decreases if the size of the purple membranes is reduced while the bacteriorhodopsin concentration is kept constant, and (e) the 532-nm light is due to the retinal chromophore of the bacteriorhodopsin molecule. The ratio of horizontal polarized hyper-Rayleigh scattered light to vertically polarized hyper-Rayleigh scattered light gives the angle (23 ± 4°) of the retinal axis with respect to the plane of the purple membrane. The hyperpolarizability of the bacteriorhodopsin molecule is found to be 5 ± 0.4 × 10(-27) esu. 相似文献
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We demonstrated the carrier control of graphene by employing the electrostatic potential produced by several types of self-assembled monolayer (SAM) formed on SiO(2) substrates. For single layer graphene on perfluoroalkylsilane-SAM, the stiffening of the Raman G-band indicates a large down shift of the Fermi level (~-0.8 eV) by accumulated hole carriers. Meanwhile, aminoarylsilane-SAM accumulated electron carriers, which compensate the hole carriers doped by adsorbed molecules under the ambient atmosphere, in graphene. The present results and their theoretical analysis reveal that the use of the dipole moments of SAM molecules can systematically modulate the electrostatic potential affecting graphene without destroying its intrinsic electronic structure and let us know that the proximity effect of the SAMs is a promising way in developing graphene-based solid state electronics. 相似文献
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A stable aqueous dispersion (5 mg ml?1) of graphene was synthesized by a simple protocol based on three-step reduction of graphene oxide (GO) dispersion synthesized using the modified version of Hummers and Offeman method. Reduction of GO was carried out using sodium borohydride, hydrazine hydrate and dimethyl hydrazine as reducing agents. The chemically synthesized graphene was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–visible absorption spectroscopy, Fourier transform infrared (FTIR) and Raman spectroscopy, thermogravimetric analysis (TGA), optical microscopy. The stability of aqueous dispersions of graphene was confirmed through zeta potential measurements and the negative zeta potentials of 55–60 mV were obtained indicating the high stability of aqueous graphene dispersions. 相似文献