一种有效的制备聚乙二醇修饰氧化石墨烯的方法

为提高氧化石墨烯(GO)的生物相容性从而扩展其在高性能生物材料制备中的应用,采用甲苯-2,4-二异氰酸酯作为桥联剂,制备了四臂星型聚乙二醇修饰氧化石墨烯(GO-TDI-sPEG),该产物在水中仍然可以稳定分散.采用傅里叶红外光谱(FTIR)、拉曼光谱(Raman)、X-射线衍射(XRD)、原子力显微镜(AFM)、透射电子显微镜(TEM)和热重分析(TGA)对接枝产物进行表征.产物在2861 cm-1和1093 cm-1处出现的特征红外吸收表明sPEG已接枝到GO上.产物的Raman光谱中D模与G模信号变弱,且ID/IG值变化不大,说明sPEG改性后的氧化石墨物理结构没有发生变化.XRD曲线上产物衍射峰消失,表明经聚合物修饰后氧化石墨被完全剥离.TGA数据表明原始GO在约160℃开始发生热失重,经修饰后,大约在260℃开始热失重,热稳定性增加了约100℃.由TEM图片可以观察到GO及改性石墨烯产物剥离程度较高,且片上分布有较多聚合物点.且AFM图片显示GO的平均厚度大约为0.85 nm,接上聚合物后部分厚度增加到约1.2 nm.     

氧化石墨烯改性ZnO/CeO2复合纳米材料的制备及其紫外屏蔽性能研究

以六水硝酸锌、六水硝酸铈、氧化石墨烯为原料,采用溶胶凝胶法制备了氧化石墨烯(GO)改性ZnO/CeO_2复合纳米紫外屏蔽剂。采用X射线衍射(XRD)、扫描电镜(SEM)、傅立叶变换红外光谱(FTIR)、紫外可见分光光度计(UV-Vis)等测试手段对产物的结构、组成及形貌进行表征,研究了氧化铈与氧化锌摩尔比、GO投入量、屏蔽剂用量以及pH值对复合纳米材料紫外屏蔽性能的影响,探索了氧化石墨烯改性ZnO/CeO_2复合纳米的最佳制备条件。结果表明:氧化石墨烯改性ZnO/CeO_2复合纳米材料中GO、CeO_2、ZnO的平均粒径分别为8. 3、15. 4、37. 5 nm。当pH 6. 0、氧化铈与氧化锌摩尔比为4∶1、GO投入量为2. 0g、屏蔽剂用量为0. 06 g/L时,紫外屏蔽性能强弱顺序为:氧化石墨烯改性ZnO/CeO_2复合纳米材料 GOZnO/CeO_2复合纳米材料 CeO_2 ZnO。     

石墨烯/三聚氰胺甲醛树脂的层状自组装及性能

以三聚氰胺(MA)和甲醛为原料,添加氧化石墨烯(GO),通过原位聚合法制备了环境友好的石墨烯/三聚氰胺甲醛树脂(GE/MF)纳米导电复合材料.采用傅里叶变换红外光谱(FTIR)、拉曼光谱(Raman)、X-射线衍射(XRD)及场发射扫描电子显微镜(FESEM)分析了复合材料的结构和形貌.通过高阻仪和热重分析仪研究了石墨烯对三聚氰胺甲醛树脂导电性和热稳定性的影响,并检测了其甲醛含量.结果表明,超声剥离之后的GO与三聚氰胺甲醛树脂自组装形成了"三明治"夹层结构的复合材料,在GO被还原成GE的同时,大大降低了产品中游离甲醛含量,提高了复合材料的导电性和热稳定性.     

硅烷功能化石墨烯/硅树脂纳米复合材料的制备与表征

先用乙烯基三甲氧基硅烷(A-171)和二甲肼改性并还原氧化石墨烯(GO),制备A-171功能化的石墨烯(FG).研究结果表明A-171与GO上的羟基发生了反应,以共价键连接到了石墨烯的表面;FG能在四氢呋喃中均匀分散并且剥离成厚度约为0.9 nm的单一片层,其干燥后表面呈褶皱状.然后将FG与双组分硅树脂用溶液共混法制备了FG/硅树脂纳米复合材料.运用X射线衍射、扫描电子显微镜、动态热机械分析、拉伸试验等手段分析了复合材料的形态与性能,结果表明,与未处理过的石墨烯相比,FG在复合材料中有更好的分散和更强的界面作用.含0.5 wt%FG的复合材料的拉伸强度较硅树脂提高了87.7%,玻璃化温度提高了23.9℃,失重5%时的温度也提高了20.1℃.     

基于氧化石墨烯的锂硫电池用聚乙烯隔膜的改性

通过简单刮涂法制备了氧化石墨烯(GO)涂覆改性的聚乙烯(PE)隔膜,并分析研究了GO的氧化程度对隔膜电学性能的影响。采用X射线光电子能谱分析(XPS)、扫描电子显微镜(SEM)、充放电实验、多硫化物透过性测试和交流阻抗等方法对GO及其改性隔膜的结构和性能进行了研究。结果表明:GO改性隔膜可以抑制锂硫电池的"穿梭效应";并且既具有较高的氧化程度,又具有较高的导电性的GO-4改性隔膜的电学性能最优;引入该隔膜的锂硫电池在0.2C条件下,首圈放电比容量为900.0mA·h/g,高于未改性PE隔膜的763.2mA·h/g。     

氧化石墨烯/聚电解质层层自组装制备单价离子选择性膜

采用层层自组装法在改性聚丙烯腈(PAN)膜表面交替沉积聚乙烯亚胺(PEI)和聚丙烯酸-氧化石墨烯(PAA-GO)混合液,制得了单价离子选择性复合膜。X射线衍射(XRD)测试结果表明成功合成了氧化石墨烯(GO)并在复合膜中均匀分散。扫描电镜(SEM)观察结果证实了多层聚电解质PEI/PAA-GO成功地组装在基膜上,并用紫外-可见(UV-Vis)光谱进一步证实了组装过程的均匀性和连续性。接触角和性能测试表明加入GO后,复合膜的亲水性和单价阳离子的选择性明显增大。这种高通量、高选择性的防污复合膜在分离和水的软化方面有很好的应用前景。     

氧化石墨烯/ZnO光催化剂制备及其降解抗生素性能

采用共沉淀法合成氧化石墨烯(GO)/ZnO片层复合光催化剂。通过傅里叶变换红外光谱、X射线衍射、扫描电子显微镜及紫外-可见漫反射光谱对复合光催化剂的结构和形貌进行表征。实验结果表明,ZnO颗粒附着在片层GO表面,复合光催化剂在可见光区的吸收强度增大。当可见光照射180 min,GO的加入量为12 mg时,GO/ZnO(GZ-3)样品对环丙沙星、氧氟沙星和诺氟沙星的降解率分别达到85.9%、85.5%和90.1%,均高于纯ZnO光催化剂。经过3次循环实验后复合光催化剂仍具有较高的光降解活性。机理分析表明,GO/ZnO复合光催化剂具有高的光催化活性的原因是GO提高了光催化剂对抗生素的吸附,并有效促进了电子的传输。     

磷酸化黄原胶/氧化石墨烯的合成及其对铀的选择性吸附

以氧化石墨烯(GO)为基体,黄原胶(XG)为交联剂,磷酸(P)为修饰剂制备了磷酸功能化黄原胶/氧化石墨烯凝胶(P-XG/GO),并应用于铀的选择性吸附。扫描电子显微镜(SEM)、X射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)、Zeta电势分析等技术表明GO的交联和磷酸化成功。系统研究了溶液pH值、铀初始浓度、吸附时间和温度等因素的影响,得到了适宜吸附条件。吸附数据用Langmuir等温线模型拟合良好,最大吸附能力为495.05 mg/g。与准一级动力学模型相比,准二级动力学模型更好地拟合了吸附过程。     

功能型单层石墨烯的热剥离法制备及其超电容性能

以氧化石墨(GO)作为前驱体,在两种不同热剥离温度下制备了两类功能型单层石墨烯.其中第一类功能型单层石墨烯通过在较低温度及空气气氛下热剥离GO制备;第二类功能型单层石墨烯通过在氮气保护下高温热剥离GO得到;利用氮气吸附-脱附方法测定了两类样品的比表面积,利用电化学测试方法分析了其超电容性能.结果表明,通过低温热剥离的方式即可以有效剥离GO;两类样品均具有较高的BET比表面积.低温热剥离GO所制备的功能型单层石墨烯在2 mol/L KOH体系中的最大比电容值约为220 F/g;而通过高温热剥离GO所制备的功能型单层石墨烯虽然同样具有较高的BET比表面积,但其最大比电容值下降至约150 F/g.这表明通过低温热剥离GO所制备的功能型单层石墨烯具有更优异的超电容性能.     

新型磁性氧化石墨烯的制备及其载药性能

通过氧化超声剥离法制备出氧化石墨烯(GO),并通过原位化学共沉淀法将其与Fe_3O4复合,得到一系列组分质量比(m_(G/F))不同的磁性氧化石墨烯复合物(GO@Fe_3O_4).用X射线粉末衍射(XRD)、拉曼光谱(Raman)、傅里叶红外光谱(FTIR)、扫描电子显微镜(SEM)和振动样品磁强计(VSM)表征了复合物的组成、微观结构和形貌及磁性能.结果表明,复合物中Fe_3O_4纳米粒子包覆在GO的表面,且两组分之间存在一定的相互作用.进一步研究表明,复合物对抗癌药物—阿霉素(DOX)的吸附行为符合二级动力学模型;正交试验结果表明,温度、DOX浓度和溶液pH都会影响复合物的载药性能,其中DOX浓度的影响最大,而溶液p H最小.此外,复合物对DOX的释放性能受溶液p H的影响较大,当pH5.8时,复合物的累积释放率最高,且重复利用率较理想.     

改进液相氧化还原法制备高性能氢气吸附用石墨烯

以液相氧化还原法为基础,并在分散剂十二烷基苯磺酸钠(SDBS)作用下制备得到高质量石墨烯,有效避免了在此过程中石墨烯大量团聚的现象.采用X射线衍射(XRD)、拉曼光谱(RS)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和原子力显微镜(AFM)等分析手段对石墨烯样品进行了表征.XRD结果体现了石墨、氧化石墨和石墨烯晶型结构的区别;SEM和TEM结果显示石墨烯呈网格状,表面平整,缺陷少;AFM分析表明样品中单层石墨烯厚度约为1.3 nm,同时也存在少许双层结构.BET测试法得到石墨烯的比表面积高达1206 m2·g-1,考察了石墨烯在高压条件下对H2的吸附性能.通过对方法改进前后所制备的石墨烯样品进行比较,结果表明,十二烷基苯磺酸钠的加入有效地减小了石墨烯的大量团聚,且得到了高质量的石墨烯.在25和55℃条件下,高质量石墨烯对氢气的吸附量分别达到1.7％(w)和1.1％(w),比之前研究结果有了很大提高.     

Morphology and isothermal crystallization of graphene oxide reinforced biodegradable poly(butylene succinate)

Graphene oxide (GO) was incorporated into poly(butylene succinate) (PBS) via a solution coagulation method to fabricate PBS/GO nanocomposites. Scanning electron microscope and transmission electron microscope observations indicated that GO with exfoliated lamella dispersed in PBS uniformly and showed good interfacial adhesion with the PBS matrix. Differential scanning calorimetry analysis suggested that the crystallization ability of PBS first increased and then decreased with increase in GO content, due to the competitive nucleating effect and confined space effect with addition of exfoliated GO. Isothermal crystallization kinetics investigation showed that the overall crystallization rate of PBS first increased and then decreased with increasing GO content while the crystallization mechanism remained unchanged. Polarized optical microscopy analysis indicated that GO worked as an effective nucleating agent for PBS. X-ray diffraction characterization suggested that incorporation of GO did not change the crystal structure of PBS. Both tensile testing and dynamic mechanical analysis witnessed the reinforcement in mechanical performance of PBS by incorporation of GO.     

Chitin/graphene oxide composite films with enhanced mechanical properties prepared in NaOH/urea aqueous solution

Chitin/graphene oxide (GO) composite films with excellent mechanical properties were prepared in NaOH/urea solution using a freezing/thawing method. The structure, thermal stability and mechanical properties of the composite films were investigated. Use of an atomic force microscope and transmission electron microscopy indicated that GO was successfully exfoliated to a single layer by ultrasonication. The results revealed that GO nanosheets were homogeneously dispersed and embedded in the chitin matrix. Due to the strong interactions between GO and the chitin matrix, the tensile strength and elongation at break of the composite film possessing 1.64 wt% GO were significantly improved by 98.7 and 114.5 %, respectively, compared with pure chitin film.     

Functionalization of Graphene Oxide with 3‐Mercaptopropyltrimethoxysilane and Its Electrocatalytic Activity in Aqueous Medium

In this work, a highly dispersed graphene oxide (GO) was successfully functionalized with 3‐mercaptopropyltrimethoxysilane (MPTS) molecule by silanization method. The chemically generated GO and MPTS functionalized GO (MPTS‐GO) were structurally characterized by thermogravimetric analysis (TGA), X‐ray diffraction analysis (XRD), scanning electron microscope (SEM), energy dispersive X‐ray (EDAX), fourier transform infrared spectroscopy (FT‐IR) and ultraviolet visible spectroscopy (UV‐Vis) techniques. The MPTS‐GO is highly suspensable in water. The thermal and conductivity results for MPTS‐GO are significantly increased compared to GO. Moreover, glassy carbon electrode modified with MPTS‐GO hybrid (MPTS‐GO/GCE) was prepared by casting of the MPTS‐GO solution on GCE. The MPTS‐GO/GCE showed an excellent electrocatalytic activity towards methionine (Met). This was understood from the observed less positive oxidation potential and higher oxidation current when compared to bare GC electrode. The MPTS‐GO has excellent electrocatalytic activity, making it an ideal candidate for sensor applications.     

Synthesis and Characterization of a Novel Graphene Oxide/titanium Dioxide Solvent-free Nanofluid

A novel graphene oxide/titanium dioxide(GO/TiO_2) solvent-free nanofluid was firstly synthesized by employing GO, which was in-situ deposited by TiO_2 as the core and(3-Glycidyloxypropyl) trime thoxysilane(KH560) and polyetheramine-M2070 as the shell. The morphology and structure of GO/TiO_2 nanofluid were verified by Transmission electron microscopy(TEM), X-ray diffraction(XRD) analysis, Fourier transform infrared spectroscopy(FTIR), X-ray photoelectron spectroscopy(XPS) and UV-vis absorption spectra. These studies confirmed that TiO_2 has been deposited onto GO with good dispersion, and the organic shell has been grafted onto the core successfully. Thermo gravimetric analysis(TGA) and viscosity analysis indicated that this nanoparticle hybrid material presented a liquid state without solvent at room temperature, and has great fluidity and thermal stability. The solubility investigation of GO/TiO_2 nanofluid revealed its excellent amphiphilicity and the potential as the functional nanocomposites.     

Electrochemical studies of few-layered graphene as an anode material for Li ion batteries

Few-layered graphene (FLG) with specific surface area of only ~8.2 m² g^?1 was synthesized from graphene oxide (GO) using microwave-assisted exfoliation. GO was prepared using modified Hummers method. Few-layered nature of the exfoliated material was confirmed by electron microscopy, X-ray and electron diffraction, and Raman spectroscopy. Coin cells were fabricated using FLG as an anode and lithium metal as a counter electrode. The cells were tested using cyclic voltammetry and galvanostatic cycling techniques. FLG showed reversible capacity values of ~400 and ~250 mAh g^?1 at current rates of 0.1 and 1 C, respectively. Columbic efficiency was more than 98 % while cycle to cycle capacity fading was less than 2 %. Maximum discharge or charging capacity was below 0.3 V, a preferable characteristic for achieving ideal anodic behavior.     

水溶液体系中氧化石墨烯的γ射线辐射还原

石墨烯是一种碳原子以二维蜂窝状晶格结构构成的单片层材料,由于其具有优异的电传导性、力学性能和热传导性近年来受到广泛关注.本文采用γ射线辐射技术分别处理水溶液和对苯二胺(PPD)水溶液中的氧化石墨烯(GO),得到辐照还原氧化石墨烯(RGO)和胺基化修饰的还原氧化石墨烯(RGON).通过傅里叶变换红外(FTIR)光谱、X射线光电子能谱(XPS)、拉曼(Raman)光谱、X射线衍射(XRD)和热失重分析(TGA)等表征分析产物的化学结构和元素组成;通过四探针测试仪和接触角测量仪研究产物的导电性能和亲水性.实验结果表明,在水溶液及PPD水溶液中γ射线辐射均可高效还原GO,还原后得到的RGO和RGON电导率均显著增大.PPD的胺基在辐射还原过程中还可以修饰到石墨烯的表面,因此RGON的亲水性比RGO好,但胺基的存在会干扰石墨烯表面π电子的传导,导致其电导率下降.     

Enhanced enantioselective oxidation of olefins catalyzed by Mn-porphyrin immobilized on graphene oxide

An efficient enantioselective heterogeneous catalyst, GO-[Mn(TPyP)tart], was prepared by covalent attachment of Mn(III) complex of H₂TPyP via the propyl linkage to graphene oxide (GO) nanosheet and using chiral tartrate counter ion. The catalyst was characterized by Fourier transform infrared (FT-IR), diffuse reflectance ultraviolet–visible (DR UV–Vis) spectroscopy, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman and thermogravimetric analysis (TGA). The graphene-supported Mn-porphyrin showed higher activity for the enantioselective epoxidation of unfunctionalized olefins with molecular oxygen in the presence of isobutyraldehyde. It could be recovered easily and reused in asymmetric oxidation of styrene precursor in a five-step sequence without any considerable loss of its catalytic activity and selectivity. The obtained optically epoxide selectivities were achieved in 86% to 100%.