Massless Electronic Excitations in Graphene Near Coulomb Impurities

Journal of Experimental and Theoretical Physics - We study low-energy massless electronic excitations in a graphene monolayer near a pointlike Coulomb impurity. We assume that such excitations are...     

氧化石墨烯纳米剪裁方法

石墨烯纳米剪裁先进方法的研究对于基于石墨烯的电子和光学设备非常重要。本文利用模板法制作反蛋白石结构,并借助反蛋白石纳米网结构,利用光催化还原氧化石墨烯,对氧化石墨烯进行纳米剪裁,形成具有纳米尺度的石墨烯。对还原后的氧化石墨烯表面进行扫描电子显微镜表征和红外光谱表征,并研究剪裁后石墨烯的电学性质。实验表明,反应时间、胶粒大小都会对剪裁后氧化石墨烯的周期和颈宽有影响,进而影响还原后氧化石墨烯的电学性质。利用纳米网状结构对石墨烯进行纳米剪裁是一种可行的方法,通过控制模板尺寸和反应条件可以控制裁剪后的性质。     

氧化锌中中性氮杂质第一性原理研究

以第一性原理计算为基础,研究了氧化锌中中性氮杂质的原子和电子结构、缺陷形成能等．根据计算结果,氮杂质为深受主,因此对氧化锌的p型导电性没有贡献．在各种中性氮杂质中,替代氧位的氮有最低的形成能和最浅的受主能级,在富氧条件下替代锌位的氮的形成能次之．氮间隙在四面体位置不稳定,会自动弛豫到kick-out结构．尽管氮可能会占据八面体间隙位置,但由于形成能过高因此其浓度会较低．同时还讨论了各种掺杂情形下的电荷密度分布,得到了自洽的结果.     

氧化石墨烯膜各向异性热传输特性研究

氧化石墨烯膜是一类新型的层状材料。本文报道了氧化石墨烯膜的面内和垂直于面方向的热扩散率和热导率,发现垂直于面方向的热导率比面内热导率低一个数量级,展示了明显的各向异性特征。氧化石墨烯膜的导热系数远低于单层石墨烯的导热系数,其原因主要是由于氧化石墨烯膜间的接触热租和氧化石墨烯膜本身导热系数较低造成的。     

Magnetic Neutron Scattering in Reduced Graphene Oxide

JETP Letters - The scale of magnetic correlations in materials based on reduced graphene oxide (RGO) has been estimated for the first time using the method of small-angle scattering of polarized...     

Science and Engineering of Graphene Oxide

Functional and synthesis diversity of graphene oxide (GO) has led to various fundamental and applied scientific explorations. GO can be viewed as an in‐plane, hybrid 2D lattice consisting of sp2 and sp3 carbon regions. Engineering the type and distribution of sp3 regions can tune the physical properties of resultant GO. This article reviews the development in the field of GO since the 19th century, with a thorough discussion on its status after the discovery of graphene in last decade. Detailed structure, optical properties, electrochemical behavior, and its viability for biological applications are discussed from both a scientific and technological perspective and a future outlook for GO research is presented.     

Unique Morphology in Polylactide/Graphene Oxide Nanocomposites

Polylactide (PLA)/graphene oxide (GO) nanocomposites with different GO loadings were prepared by solution blending using tetrahydrofuran (THF) as solvent. The morphologies of the nanocomposites in the cast films and in subsequently isothermally crystallized samples were investigated separately. According to polarized optical microscopy images of the composites after isothermal crystallization, it was deduced that GO had nucleation effects on the crystallization of PLA and led to the size of spherulites decreasing and the number of spherulites increasing. However, by virtue of SEM, unique microsphere morphologies were found in the cast films of the PLA/GO composites. It was found that the features of this kind of microsphere were not influenced by the compositions but by the evaporation rate of the solvent during the preparation of the cast films. A faster evaporation rate of solvent resulted in smaller size of the microspheres. Based on DSC and FTIR results, it was proposed that the forming of this kind of microsphere was related to hydrogen bonds being formed between PLA and GO. The unique microsphere morphology is suggested to provide a new method to prepare PLA microsphere-based scaffolds.     

Optical and Electrical Properties of Graphene Oxide

Optics and Spectroscopy - The Raman spectra and the temperature dependence of the electrical resistance of graphene oxide in the process of continuous heating and cooling in an argon atmosphere in...     

Functionalization of Graphene Oxide and its Biomedical Applications

Graphene oxide (GO) offers interesting physicochemical and biological properties for biomedicine due to its versatility, biocompatibility, small size, large surface area, and its ability to interact with biological cells and tissues. GO is a two-dimensional material of exceptional strength, unique optical, physical, mechanical, and electronic properties. Ease of functionalization and high antibacterial activity are two major properties identified with GO. Due to its excellent aqueous processability, amphiphilicity, surface functionalization capability, surface enhanced Raman scattering (SERS), and fluorescence quenching ability, GO chemically exfoliated from oxidized graphite is considered a promising material for biological applications. In addition, due to π-π* transitions, a low energy is required for electron movement, a property important in Biosensor and Bioimaging applications of GO. In this article, we present an overview of current advances in GO applications in biomedicine and discuss future perspectives. We conclude that GO is going to play a vital role in Biomedical applications in the near future.     

Spectral and Kinetic Studies of Photochromic Systems Based on Graphene and Graphene Oxide Nanostructures

Optics and Spectroscopy - A comparative spectral and kinetic study of the reactions of thiol-substituted molecules of diarylethene and spirooxazine with graphene nanoparticles and graphene oxide...     

电感耦合等离子体质谱法测定高纯氧化钕中稀土杂质的研究

本文报导了高纯氧化钕中Ｙ、Ｌａ、Ｃｅ、Ｐｒ、Ｓｍ、Ｅｕ、Ｇｄ、Ｅｒ、Ｔｍ、Ｙｂ、Ｌｕ等１１中稀土杂质的电感耦合等离子体质谱测定方法。选择了仪器最佳操作参数，研究了质谱干扰和基体效应，采用Ｔ１内标可基本克服基体效应。方法检出限为０．０１９－０．０９５ｎｇ／ｍＬ，加标回收率为８１．８％－１０３．３％。     

高纯Tb_4O_7中稀土杂质的ICP－MS法测定

本文报导了高纯氧化铽中Ｌａ、Ｃｅ、Ｐｒ、Ｎｄ、Ｓｍ、Ｅｕ、Ｇｄ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ、Ｙｂ、Ｙ等１３种稀土杂质的电感耦合等离子体质谱测定方法。选择了仪器最佳操作参数，考察了质谱干扰和基体效应，选用Ⅰ作内标可基本克服基体效应，方法检出限为０．０１３－０．１１ｎｇ／ｍＬ，加标回收率为８７％－１０３％，重复精度（ｎ＝７）为２．２％－５．５％。方法快速、灵敏、准确。     

Multifunctional Hybrids Based on 2D Fluorinated Graphene Oxide and Superparamagnetic Iron Oxide Nanoparticles

Carbon‐based nanomaterials have garnered a lot of attention in the research of yesteryear. Here this study reports a composite based on fluorinated graphene oxide—a multifunctional subsidiary of graphene; and iron oxide nanoparticles as a contrast agent for magnetic resonance imaging (MRI). Extensive structural and functional characterization is carried out to understand composite behavior toward biotoxicity and its performance as a contrast agent. The electron withdrawing fluorine group decreases the charge transfer to iron oxide increasing the magnetic saturation of the composite thus enhancing the contrast. The interaction of paramagnetic and superparamagnetic systems yields a superior contrast agent for MRI and fluorescent imaging.     

Effect of Oxide Content of Graphene Oxide Membrane on Remarkable Adsorption for Calcium Ions

Graphene oxide membranes(GOMs), as one of the most promising novel materials, have gained great interest in the field of adsorption. However, the oxygen content of graphene oxide is directly related to its adsorption properties, such as suspension stability, adsorption capacity, and reusability of GOMs. Here, a series of reduced GOMs with oxygen content from 28% to 12% were conveniently prepared by the thermally reduced and the corresponding interlayer spacing of these membranes changed from 8.0 ? to 3.7 ?. These prepared GOMs have remarkable Ca~(2+) adsorption capacity, which increases with the oxygen content or interlayer spacing of GOMs.Importantly, the max adsorption capacity of the mass ratio between adsorbed Ca~(2+)and pristine GOMs can reach up to 0.481 g/g, which is about one order of magnitude higher than the adsorption capacity of activated sludge,magnetic Fe_3 O_4, functionalized silica, zeolite molecular sieve, and other reported previously. Moreover, GOMs show excellent stability and the Ca~(2+) can be easily desorbed by water, so that the GOMs can be reused. Our previous theoretical analysis suggests that this remarkable adsorption is attributable to the strong interactions between Ca~(2+) and GO sheets, including the ion- interactions between Ca~(2+) and aromatic graphitic rings as well as the electrostatic interaction between Ca~(2+) and oxygen-containing groups.     

氧化石墨烯如何猝灭罗丹明6G的荧光

考察了水相溶液中氧化石墨烯对罗丹明6G的高效荧光猝灭．借助稳态及时间分辨荧光光谱测量,结合对该二元体系线性吸收谱变化的细致分析,澄清了相关荧光猝灭机理,即动态猝灭与静态猝灭的联合猝灭机制．提出在静态猝灭过程中罗丹明6G与氧化石墨烯所形成的可能的基态复合物,并进一步讨论了二者之间的光致电子转移过程．     

Features of the Temperature Dependence of Graphene Oxide Resistivity

The Raman spectra and the temperature dependence of the resistivity of graphene oxide grown upon continuous heating and cooling on a glass substrate is studied in air in the temperature interval of 300–550 K. It is established that the intensity of the D-peak falls relative to the G-peak, the maximum of which shifts toward lower frequencies in Raman spectra. Partial removal of oxygen-containing functional groups is accompanied by a reduction in resistivity from 5.6 × 10⁹ to 5.4 × 10⁹ Ω. In the temperature intervals of 300–350 K and 300–375 K, the resistivity is constant upon graphene oxide heating and cooling, respectively.     

高温还原氧化石墨烯膜及其导热性能

采用氧化还原法制备了结构致密且具有较高柔韧性的石墨烯薄膜,探究了薄膜经过较高退火温度还原后结构变化,并通过T型稳态法测量了其热导率,研究了还原温度对薄膜热导率和力学性能的影响。结果表明,高温还原有助于氧化石墨烯中含氧官能团的去除和sp2杂化碳晶格的恢复,并且温度越高还原效果越好。当还原温度高达2800℃时,在200~350 K温度范围内石墨烯膜的热导率在336.9~436 W·m^-1·K^-1之间,伴随着温度的升高,热导率有先增大后减小的趋势。