石墨烯及其复合材料在锂硫电池中抑制穿梭效应的应用进展

硫锂电池具有比能高达1675 mAh g?1、价格低廉、环保等优点,是一种具有良好应用前景的二次电池.但由于放电过程中多硫化物溶解产生的穿梭效应、硫的绝缘和硫电极的体积膨胀等原因导致锂硫电池的循环稳定性还不能满足工业化要求.石墨烯具有优异的导电性、超大的比表面积、良好的机械柔韧性和热化学稳定性,因此石墨烯及其衍生物成为...     

Ag/石墨烯复合材料的制备及其对邻氨基苯甲酸甲酯的SERS效应

以还原的氧化石墨烯(r-GO)为前驱物,采用紫外光照还原和水合肼还原两个不同的合成过程,简单制得了没有有机分子存在的Ag沉积r-GO纳米复合材料,其中被还原的Ag呈颗粒状沉积在r-GO片层表面。由于紫外光照还原反应速率较慢,制得的Ag颗粒分散性相对较好,尺寸分布较窄,粒径主要处在25~80 nm间;而用水合肼还原,因反应速率较快,获得的Ag颗粒团聚较严重,尺寸分布较宽,粒径主要处在20~130 nm间。在此基础上,以一种香料邻氨基苯甲酸甲酯为标记分子,在波长为785 nm激光激发下,对获得的一系列含Ag复合材料进行了表面增强Raman散射光谱(SERS)测试,结果表明,它们具有非常高的SERS效应,增强因子在108附近,其中,用水合肼还原制得的复合材料SERS效应更加明显。     

石墨烯负载氧化铁在电磁屏蔽中的应用研究

研究了石墨烯负载氧化铁的制备工艺条件和电磁性能,并对石墨烯负载氧化铁复合材料的电磁屏蔽性能进行了测试,结果表明,石墨烯负载氧化铁后,磁性能获得提升,复合粒子材料具有较好的电磁屏蔽性能。     

氧化石墨烯还原制备石墨烯的方法研究

以天然鳞片石墨为原料,对Hummers法制备的氧化石墨烯,分别采用氢碘酸、葡萄糖、乙二胺、氢氧化钠进行化学还原,同时对比用快速热处理制备石墨烯。利用傅立叶红外光谱（FT—IR）、拉曼光谱（Raman）、扫描电子显微镜（SEM）对所得产物进行了比较分析。结果表明：对Hummers法制备的氧化石墨烯还原,葡萄糖的还原效果比较好;通过热处理可有效地将氧化石墨烯的含氧官能团还原,是一种高效、可行的方法。     

高性能石墨烯电磁屏蔽材料的研究进展

近年来,电磁干扰及电磁兼容问题日益加剧,严重危害军民领域仪器、仪表等电子设备的安全运行,亟待开发出新型高性能电磁屏蔽材料。石墨烯是一种新型的二维碳纳米结构材料,具有优异的物理与化学性能,为柔性、轻薄、服役性能好的电磁屏蔽材料设计提供了新的解决方案。从电磁屏蔽的基本原理出发,介绍了电磁波屏蔽和损耗的机理及能量转化方式。进一步对石墨烯电磁屏蔽材料进行了系统地分类与归纳,综述了近年来石墨烯电磁屏蔽材料的屏蔽效能和研究进展,对石墨烯电磁屏蔽材料面临的挑战和发展前景进行了展望。     

氧化石墨烯的制备及电化学性质研究

采用改进Hummers法来制备氧化石墨烯;通过循环伏安法、单电位阶跃计时电流法、塔菲尔曲线研究分散在DMF中的氧化石墨烯在Pt电极上的电化学性质,研究表明氧化石墨烯在Pt电极上电化学反应是一步不可逆的反应,并且此过程是受扩散控制;通过循环伏安法求得电荷传递系数α为0.03348。通过塔菲尔曲线可计算得交换电流密度i0为1.007×10-4 A/cm2。氧化石墨烯在Pt电极上成核机理的研究表明,氧化石墨烯在Pt电极上是按三维模式扩散控制下连续成核的。     

氮化硼/石墨烯共混对环氧树脂复合材料导热性和形状记忆效应的影响

采用不同摩尔比的熔融氢氧化钠和氢氧化钾剥离六方氮化硼。分别利用原子力显微镜、扫描电子显微镜和透射电子显微镜观察剥离效果发现,氢氧化钠和氢氧化钾摩尔比为2∶1时,氮化硼被剥离成4个原子层的氮化硼纳米片,剥离效果较好。为了提高环氧树脂的导热性,研究了不同质量比的氮化硼纳米片(BNNS)和石墨烯(Gr)混合物对其导热性能的影响。实验结果表明,BNNS和Gr混合物对环氧树脂导热性的影响优于单一的BNNS和Gr。当m(BNNS)∶m(Gr)=1∶4时,环氧树脂的导热系数最高,从纯环氧树脂的0.22 W/(m·K)增加到0.42 W/(m·K)。同时,该混合物还改善了环氧树脂的形状记忆效果,当m(BNNS)∶m(Gr)=1∶4时,复合材料的形状回复率可达到100%;70℃时,纯环氧树脂的形状回复时间为30 s,复合材料的形状回复时间缩短为4 s。     

润滑油中石墨烯分散方法研究现状

因石墨烯具有自润滑和自修复性能,在润滑油领域引起了大家的研究兴趣。应用在润滑油中时,石墨烯的分散性是难点之一,也是提升润滑性能的前提条件。应用于石墨烯分散的方法有物理、化学两种,物理分散包括机械、超声、球磨分散,化学分散包括表面改性、元素掺杂、纳米复合等。总结了近年来国内外润滑油中石墨烯均匀分散方法的研究进展和成果,并简要分析了相关机理。     

石墨烯纳米片超声分散的研究

为获得分散均匀无污染、不团聚的的石墨烯纳米片,通过超声处理技术分散已团聚的石墨烯纳米片并研究了主要影响因素——超声功率和超声时间在分散过程中对石墨烯纳米片分散效果和结构的影响。利用场发射电子显微镜、透射电子显微镜、傅里叶变换红外光谱、X射线光电子能谱、拉曼光谱、原子力显微镜对超声分散后的石墨烯纳米片的形貌、尺寸和结构进行表征与分析。结果表明,延长超声时间或增加超声功率可以显著提高石墨烯纳米片的分散效果,但相应的也一定程度降低了石墨烯纳米片的尺寸,生成大量的边缘型缺陷,尤其当功率过大或时间过长时甚至会生成空位缺陷。当超声功率960 W,超声时间4 h时石墨烯纳米片的分散效果最好,且破碎程度相对较低。     

轻质石墨烯基电磁屏蔽材料的研究进展EI北大核心CSCD

随着先进电子科学技术的迅速发展,电磁辐射造成的电磁污染、电磁干扰、泄密等问题已经成为电子、航天、航空、信息、通信等领域关注的重要问题,本文基于电磁屏蔽的基本理论与石墨烯的主要制备方法,针对不同的应用场合,综述了石墨烯基块体电磁屏蔽材料、泡沫电磁屏蔽材料、柔性薄层电磁屏蔽材料、高温电磁屏蔽材料4大类轻质电磁屏蔽材料的研究进展。同时,概述了石墨烯基电磁屏蔽材料的主要设计思路和制备方法,讨论了电磁屏蔽材料中的基本科学问题。基于应用发展的需求,分析了未来新型电磁屏蔽材料的发展方向和趋势,为发展设计新一代轻质高性能电磁屏蔽材料及结构提出了新的构想。     

Strain-Controlled Valley Polarization in a Graphene Under the Modulation of a Realistic Magnetic Field

Journal of Superconductivity and Novel Magnetism - Valley polarization is one basic concept in valleytronic device applications. However, the coexistence of this scenario in graphene under the...     

Intensity Modulation Produced by Crossed Electric and Magnetic Field Electron Image Deflection Systems

It was found that intensity fringes were produced in a crossed electric and magnetic field electron image deflection system. The origin of these fringes is discussed.     

Calculation of Electric Arc in Longitudinal Magnetic Field

A steady-state three-dimensional mathematical model is used to calculate an electric arc in an external longitudinal magnetic field. A helical shape of arc is obtained in the case of a certain correlation between the external parameters being regulated. The possibility of using the mathematical model for numerical analysis of helical arcs is demonstrated.     

Hybrid Reduced Graphene Oxide with Special Magnetoresistance for Wireless Magnetic Field Sensor

Very few materials show large magnetoresistance(MR)under a low magnetic field at room temperature,which causes the barrier to the development of magnetic field sensors for detecting low-level electromagnetic radiation in real-time.Here,a hybrid reduced graphene oxide(rGO)-based magnetic field sensor is produced by in situ deposition of FeCo nanoparticles(NPs)on reduced graphene oxide(rGO).Special quantum magnetoresistance(MR)of the hybrid rGO is observed,which unveils that Abrikosov's quantum model for layered materials can occur in hybrid rGO;meanwhile,the MR value can be tunable by adjusting the particle density of FeCo NPs on rGO nanosheets.Very high MR value up to 21.02±5.74%at 10 kOe at room temperature is achieved,and the average increasing rate of resistance per kOe is up to 0.9282ΩkOe^-1.In this paper,we demonstrate that the hybrid rGO-based magnetic field sensor can be embedded in a wireless system for real-time detection of low-level electromagnetic radiation caused by a working mobile phone.We believe that the two-dimensional nanomaterials with controllable MR can be integrated with a wireless system for the future connected society.     

Orientational Effect of the In-Plane Magnetic Field on the FFLO Modulation in Layered Superconductors

We present the analysis of the Fulde–Ferrell–Larkin–Ovchinnikov phase in an s-wave superconducting layered system in parallel magnetic field. We show that in the close vicinity of the tricritical point in the system with elliptical Fermi surface the orbital effect pins the FFLO modulation vector perpendicular to the applied magnetic field. At low temperatures, the FFLO modulation can acquire different directions.     

磁场结合气调包装对葡萄保鲜效果的研究

用不同强度的磁场对葡萄进行处理,并结合气调包装,对其失重率、可溶性固形物、VC含量、可滴定酸含量、呼吸强度和葡萄硬度等进行了对比研究。结果表明:强度为1 A的磁场处理的葡萄失重率明显降低,VC含量、可滴定酸含量和呼吸强度明显提高,但与对照组相比,可溶性固形物含量变化不明显。     

Phase Transitions in Liquid Crystal Doped with Magnetic Particles of Different Shapes in Combined Electric and Magnetic Fields

We have studied the influence of electric and magnetic fields on the orientational structure of ferronematics based on a thermotropic nematic 4-trans-4 \(^{\prime }\) -n-hexylcyclohexyl-isothiocyanato-benzene (6CHBT). The 6CHBT liquid crystal has been dissolved in phenyl isothiocyanate and doped with rod-like or chain-like magnetic particles. In such a mixture, the phase transition from an isotropic to a nematic phase is via a droplet state, i.e., coexistence of nematic and isotropic phases. The obtained results showed that a combination of the electric and magnetic fields can change the character of a phase transition from the isotropic to the nematic phase via the droplet state in such systems. Moreover, magneto-dielectric measurements of structural transitions showed the magnetic field induced a shift of the phase transition temperature from the isotropic to the droplet state.     

Graphene Field Effect Transistors with Mica as Gate Dielectric Layers

Chemical vapor deposited monolayer graphene is transferred onto atomically flat and ultra‐thin muscovite mica to study the transport characteristics of graphene with a test structure of mica‐based graphene field effect transistor (GFET). The transfer curve of the 24 nm mica‐based GFET shows an effective carrier mobility of 2748 cm²/Vs and a transconductance of 3.36 μS, a factor of 2 and 7 larger than those values obtained from 40 nm SiO₂ based GFET, respectively. The results demonstrate that mica is an excellent gate dielectric material due to its high dielectric constant, high dielectric strength, and atomically flat surface.