扫描探针显微镜在石墨烯研究中的应用

石墨烯是近年来材料、电子和纳米科学中的热门研究课题之一。石墨烯独特的二维结构和原子尺度的平整性使其特别适合利用扫描探针显微镜进行深入研究。利用扫描探针显微镜可以对石墨烯样品的表面的电学、力学和光学等性质进行细致的表征;同时,还可以对石墨烯进行精细的纳米尺度微加工。本文以各种扫描探针显微镜为基础,综述了扫描探针显微镜在石墨烯研究中起到的重要的表征和加工作用。同时,还详细介绍了石墨烯表面研究中的最新进展,并对扫描探针显微镜在石墨烯研究中所具有的潜力进行了探讨。     

石墨烯的氧化与抗菌特性

氧化石墨烯(GO)的抗菌机制(破坏细菌结构、氧化应激和阻断细菌传输)只从宏观角度论述了 GO整体结构对细菌的作用,但未能说明表面官能团对抗菌的贡献.在不同气氛(N2或O2)下退火对石墨烯进行表面官能团修饰,得到表面官能团组成不同的氮气处理石墨烯(NTG)、氧气处理石墨烯(OTG).平板菌落计数法抗菌测试表明,OTG有更...     

氧化石墨烯的制备还原及应用进展

随着石墨烯产业的蓬勃发展,氧化石墨烯作为制备工程化应用石墨烯的中间体产物而备受关注.同时由于其自身优异的物理化学性质,使其在各大领域均有前所未有的新兴应用.作者针对国内外氧化石墨烯的各种结构模型、制备方法、性质和相关应用,以及氧化石墨烯的还原进行了总结与概述.在对比各种方法的基础上,作者提出了氧化剂和还原剂的选择是反应的关键要素,归纳了选择的基本原则.最后,指出氧化石墨烯制备和还原研究中还需解决的问题,并对其发展和影响做出了评价和展望.     

石墨烯在电子器件研究中的应用

石墨烯是近年来逐步发展起来的新型电子材料,具有导电性好、电子迁移率高、比表面积大、导热率高、弹性好等优点,石墨烯的开发和应用已成为纳米材料、生物、化学以及电子信息等多个领域的研究热点。围绕近年来石墨烯在电子器件中的应用研究,本文主要对其在生化传感器、高速器件、太阳能电池、储能器件、柔性器件5个热点方向中的部分研究成果进行综述。     

石墨烯在显示技术中的应用及专利分布状况

近年来,石墨烯作为一种全新的材料受到各国政府、企业和科研机构的广泛关注,有关石墨烯的制备和应用技术也得到了长足的发展。基于石墨烯的优良性质,其可以用于制造显示屏等显示器件,以取代传统的透明导电氧化物(TCO)显示器件。本文介绍了石墨烯在显示技术中的应用情况以及专利分布状况。     

单层石墨烯在空气中的热稳定性研究

采用化学气相沉积方法制备了高质量的大面积单层石墨烯,利用拉曼光谱、X射线光电子能谱和原子力显微镜对在空气中热处理前后的石墨烯进行了表征,研究了单层石墨烯在空气中的热稳定性。结果表明,在空气中热处理后,石墨烯的缺陷明显增加,晶粒发生细化,其主要是由于热处理后石墨烯会发生轻微的氧化,表面形成C O及C—OH键。另外,由于石墨烯与衬底的结合形态有所变化,使得热处理后石墨烯表面更趋平整。     

石墨烯基材料的能带调控技术研究进展

石墨烯具有一系列特殊的物理和化学性质,因而近年来受到人们的极大关注.然而目前石墨烯在光电子领域的应用尚不广泛,其主要原因是由石墨烯的半金属性决定的,所以将石墨烯由半金属转变为半导体就成为人们关注的一个焦点问题.我们针对石墨烯能带调制问题开展了系统的石墨烯基材料与器件的制备研究,开发了单层、双层石墨烯的CVD制备技术、氧化石墨烯的\     

氧化石墨烯/液晶弹性体复合膜的性能研究

近年来,氧化石墨烯/液晶弹性体复合膜凭借其稳定高效的光热性能,受到科学家的广泛关注。但目前研究者大多重点关注其光热响应行为及使用场景,并未系统研究外界刺激的强弱和复合膜自身的尺寸大小对其响应性能的影响。本文采用旋涂的方法在制备的具有固定取向的液晶薄膜上涂覆一层氧化石墨烯,制备了具有不同液晶分子取向的氧化石墨烯/液晶弹性复合膜,可以实现红外光和温度的双重刺激响应,并对其进行了响应性能和形变规律的表征和分析。实验结果表明,氧化石墨烯/液晶弹性体复合膜是一种红外-热响应型的复合膜,该复合膜由于裁剪方向的不同,会呈现2种不同的形变规律,以此为基础,研究了不同强度外场刺激下复合膜的响应特性,以及复合膜自身尺寸的不同对复合膜响应特性产生的影响。发现1型复合膜的响应性能主要受宽度影响,2型复合膜的响应性能主要受长度影响,为氧化石墨烯/液晶弹性体复合膜的应用提供了基础。使用该复合膜制备了仿生光热驱动器,证明了其在生物仿生领域的潜力。     

多肽聚合物对氧化石墨烯材料稳定性的研究

为进一步提高氧化石墨烯在水溶剂中的稳定性,文中采用多肽聚合物对氧化石墨烯进行表面改性。傅里叶红外变换光谱和热重分析表明,两者可以通过非共价键的方式进行复合。然后,用紫外可见光吸收光谱法测定分散液浓度,表征氧化石墨烯分散液的稳定情况,并探索多肽聚合物修饰氧化石墨烯时的最佳添加量,在此基础上又探索了多肽聚合物对氧化石墨烯在水溶剂中长期稳定性的影响。实验结果表明,在氧化石墨烯浓度为1 mg/mL的条件下,当加入的多肽聚合物与氧化石墨烯的质量比为3:100时,可以有效避免氧化石墨烯片层的再次团聚,经多肽聚合物修饰过的氧化石墨烯在水溶剂中表现出良好的稳定性,且经过8周静止后也没有明显的沉淀产生。     

Effect of characteristic properties of graphene oxide on reduced graphene oxide/Si schottky diodes performance

We investigated the effect of the size of graphene oxide (GO) sheets made with two different types of GO solution on the performance of Si-based solar cells. Large-sized reduced GO (rGO) with an in-plane crystalline diameter of 3.42 nm has smaller defect sites and thus the Si/rGO Schottky junction solar cell shows a lower leakage current than the solar cell with small-sized rGO (i.e. an in-plane crystalline diameter of 3.03 nm). Enhanced open-circuit voltage (V_oc) and improved short-circuit current (J_sc) are observed for the solar cell with large-sized rGO due to the increased work function and Schottky barrier height at the Si and rGO junction. In other words, an increased built-in potential and a wider depletion region of the solar cell with large-sized rGO contribute to the increased carrier absorption and generation. These findings indicate that (i) rGO acts as a good transparent conducting layer and hole-transporting layer, and (ii) the control of rGO size in Si/rGO Schottky junction solar cell is important to improve the performance.     

石墨烯及石墨烯场效应管的辐照效应研究进展

石墨烯由于高迁移率、高导热性、柔韧性好和机械强度高等优异性能使其成为构筑新型纳米电子器件的重要材料,已成为电子信息、生物医学、显示等领域的研究热点。当石墨烯材料及其电子器件放置于含有辐照因素的场景中时,会因为与高能光子和带电粒子等相互作用而改变晶格结构或积累电荷,使石墨烯材料及电子器件的性能发生变化。本文主要综述了典型辐照因素对石墨烯及器件的主要效应及研究进展,旨在总结不同辐照在石墨烯及其电子器件中引发的物理效应,归纳其微观-宏观性质变化,为加深石墨烯材料及器件的辐照效应的理解,推动其在辐照场景中的实际应用奠定基础。     

Palladium-decorated zinc sulfide/reduced graphene oxide nanocomposites for enhanced visible light-driven photodegradation of indigo carmine

The removal of toxic organic pollutants from wastewater using reduced graphene oxide (rGO) based photocatalysts has dominated recent scientific research. As a result numerous nanomaterials have been studied and used for wastewater remediation. ZnS has been widely studied due to its versatile application in photocatalysis. This study presents the synthesis of a series of Pd-decorated ZnS/rGO nanocomposites by a coprecipitation method. The materials were characterized using Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM)–EDS, UV/visible spectrophotometry, and BET surface area analysis. Indigo carmine (IC) dye (20 ppm) was chosen as a model for organic pollutants and was used to evaluate the photocatalytic performance of the Pd–ZnS/rGO nanocomposites under simulated solar light with varying concentrations of Pd in the host material. Pd–ZnS/rGO showed significant visible light induced photocatalytic activity towards the degradation of IC. Highest photocatalytic activity was observed for the 1.0% Pd–ZnS/rGO sample (k=2.19×10⁻² min⁻¹).     

Rapid microwave-assisted synthesis of silver decorated-reduced graphene oxide nanoparticles with enhanced photocatalytic activity under visible light

A facile, fast, and scalable microwave irradiation (MWI) method for the synthesis of Ag nanoparticles (Ag NPs) dispersed on graphene sheets has been developed. The reduction of graphene oxide takes place in ethanol solution within 2 min of MWI without any additional reducing agent or complicated treatment. The morphology and microstructure of the as-prepared hybrid were characterized by Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) images. The result showed the Ag NPs with an average size of 5–10 nm decorated on the rGO sheets. X-ray powder diffraction (XRD) determined that the crystallographic structure of Ag is face-centered cubic and there was a strong interaction between Ag NPs and rGO sheets. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) showed that GO had been reduced to rGO in our hybrid. Moreover, visible photocatalytic activity of the rGO–Ag nanocomposites was tested using Rhodamine B (RhB) as the model contaminant. This result indicates that rGO–Ag nanocomposites display distinctly enhanced photocatalytic activities. The investigation gave a promise to the development of original yet highly efficient graphene-based photocatalysts that utilize visible light as an energy source.     

N-type polymeric organic flash memory device: Effect of reduced graphene oxide floating gate

In this paper, n type nonvolatile memory devices were fabricated by implanting a bilayer (rGO sheets/Au NP) floating gates, using n-type polymer semiconductor, poly {[N, N′ bis (2octyldodecyl) - naphthalene-1, 4, 5, 8 - bis (dicarboximide)-2,6-diyl] – alt - 5,5′ - (2, 2′ bithiophene)} [P(NDI2OD-T2)n]. In the developed organic field effect transistor memory devices, electrons are trapped/detrapped in rGO sheet/Au NP's nano-floating gates by controlling the charge carrier density in the active layer through back gate bias control. The devices showed interesting non-volatile memory properties with a large memory window of ∼34 V, a programming-reading-erasing cycling endurance of 103 times and most importantly, an improved retention time characteristics estimated by extrapolation (longer than the technological requirement of commercial memory devices (>10 years)). This approach provides a great potential for fabricating high-performances organic nano-floating gate memory devices and opens up a new way for the development of next-generation non-volatile memory devices.     

螺原体超微形态的电镜研究

应用透射电镜对从患＂爬蜂病＂的蜜蜂体内分离到的螺原体（Spiroplasma meilliferum CH-1）在不同生长繁殖时期的超微形态结构进行观察和比较,并在低渗条件下对螺原体的细胞骨架结构进行研究。结果表明：螺原体在四个不同的生长时期呈现不同的形态学特征,尤以在对数生长期形态最为多样,除典型的螺旋特征外,还有串珠、出芽和分枝等结构,提示螺原体可能通过二分裂、多分裂、缢缩、出芽等多种方式繁殖。此外,本文在低渗条件下观察到螺原体菌体胞质内的微丝和微管样细胞骨架结构,为进一步研究螺原体的运动模式提供了重要技术途径。     

Electron-beam-induced reduced graphene oxide as an alternative hole-transporting interfacial layer for high-performance and reliable polymer solar cells

We demonstrate an eco-friendly, simple, and cost-effective method for manufacturing reduced graphene oxide (GO) induced with electron-beam irradiation, and we investigate the feasibility of the electron-beam-induced reduced GO (ERGO) as a hole-transporting interfacial layer in polymer solar cells (PSCs). In addition, the chemical composition, conductivity, work-function, and morphology of ERGOs with various absorbed doses were systematically investigated. The analytical results revealed that the reduced GO (RGO) was successfully prepared using electron-beam irradiation, and the electrical conductivity of ERGO was increased (up to 18.3 S/cm) with increasing the amount of absorbed dose. The PSCs with the ERGO as a hole-transporting interfacial layer exhibited comparable cell performance (3.52 ± 0.08% of power conversion efficiency) to that of the conventional PSCs with the poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), and they had better stability than the PEDOT:PSS-based PSCs. From the results, we confirmed that electron-beam irradiation is an effective approach to prepare the RGO, and the ERGO was preferable to the PEDOT:PSS for high-performance and stable PSCs.     

Modulation of charge transport properties of reduced graphene oxide by submonolayer physisorption of an organic dye

We have examined the effect of submonolayer coverage of 1-pyrene butyric acid on charge carrier transport in reduced graphene oxide. We have modeled the interaction of 1-pyrene butyric acid molecules with graphene and determined the amount of charge transfer at the interface between the two materials. The effect of 1-pyrene butyric acid as electron acceptor was determined by transfer characteristics measurements on thin film transistors for thick layers. By using time-resolved photocurrent measurements we were able to detect a reduction of electron mobility in reduced graphene oxide for coverage as low as 0.08%.