原位聚合法制备PANI/RGO导电复合材料的性能

采用原位聚合法制备聚苯胺(PANI)、PANI/氧化石墨烯(GO)复合材料和PANI/还原氧化石墨烯(RGO)复合材料。利用四探针测试仪、X射线衍射(XRD)仪、傅立叶变换红外光谱(FTIR)仪、热重(TG)分析仪和扫描电子显微镜(SEM)等对PANI及PANI/GO复合材料和PANI/RGO复合材料进行表征。电导率测试结果表明,当加入GO质量分数为50%时,先还原后聚合法制得PANI/RGO复合材料的导电率可达9.916 S/cm,RGO能有效提高复合材料的导电性;XRD和FTIR分析结果表明,GO和RGO都能较好分散在PANI中;TG分析结果表明,将GO还原为RGO后在小于250℃时能有效提高复合材料的热稳定性。通过原位聚合法能将GO和RGO较好分散在PANI中,形成较好的插层型复合材料,尤其是先还原后聚合法制得的PANI/RGO复合材料具有较好的导电性和热稳定性。     

聚苯胺/氧化石墨烯接枝复合材料的制备及电容性能研究

利用化学氧化法原位聚合制备了聚苯胺(PANI)/氧化石墨烯(GO)接枝复合材料。透射电子显微镜表明,PANI纳米颗粒均匀地分布在GO的表面;通过UV-vis光谱证实了GO和PANI之间存在着强烈的相互作用;充放电测试表明,PANI/GO纳米复合材料具有良好的电荷储存特性,最高比电容可达575 F/g。由于与GO之间的化学结合作用,PANI的充放电循环稳定性得到明显提高。     

石墨烯/热塑性聚氨酯薄膜的制备及性能

采用热还原的方法由氧化石墨烯(GO)制备得到还原石墨烯(RGO),并将两种石墨烯与热塑性聚氨酯(TPU)复合制得纳米复合材料薄膜。进而考察了两种纳米复合材料薄膜的导电、导热及力学性能。结果表明:在TPU中加入GO能够得到高导热、低导电的纳米复合材料,而加入RGO则得到高导热、高导电的纳米复合材料;同时,GO和RGO的加入,均能显著提高TPU的拉伸强度和模量。     

高电活性石墨烯/聚苯胺纳米复合材料的制备和表征

采用了一种简单有效地方法制备了高电活性的石墨烯/聚苯胺复合材料。首先,将苯胺在氧化石墨烯（GO）的水性分散液中氧化聚合,制备了氧化石墨烯/聚苯胺（GO/PANI）,再将GO/PANI与水合肼反应,制得还原-氧化石墨烯/聚苯胺（R（GO/PANI））。利用透射电子显微镜（TEM）,热失重分析（TGA）和循环伏安法（CV）对GO/PANI和R（GO/PANI的形貌,热稳定性和电化学性能进行了分析研究。结果表明,GO表面存PANI,且R（GO/PANI）的热稳定性和电活性都明显高于GO/PANI。     

用一步法原位制备氢化丁腈橡胶/还原氧化石墨烯纳米复合材料

将氢化丁腈橡胶(HNBR)与石墨烯二维纳米材料(GO)共混以提高其导电和导热性能,采用乳液一步法还原制备了HNBR/还原氧化石墨烯(RGO)纳米复合材料。结果表明,丁腈橡胶(NBR)乳液中分子链的碳碳双键和GO经水合肼/过氧化氢/硫酸铜催化体系产生的活性中心二酰亚胺被同时进行加氢和还原,这在改善HNBR性能的同时简化了RGO纳米复合材料的制备工艺,制备过程没有毒性大的有机溶剂。HNBR/RGO纳米复合材料的氢化度为61%,I_D/I_G为1. 36,说明NBR/GO中分子链双键和GO经一步法得到还原。采用一步法可将RGO在HNBR基质中均匀分散。HNBR/RGO纳米复合材料的力学性能和热性能因RGO的存在得以大幅度改善。     

石墨烯携载无机纳米粒子的制备及拉曼性能研究

通过原位复合的方法,在石墨烯片层间掺杂纳米银颗粒,制备出石墨烯/银纳米杂化材料(RGO/Ag)。利用紫外吸收光谱、傅里叶红外光谱、透射电子显微镜(TEM)、XRD、拉曼光谱等对氧化石墨烯(GO)、还原氧化石墨烯(RGO)和石墨烯/银纳米杂化材料(RGO/Ag)进行表征。发现复合材料中的银对石墨烯/银材料有拉曼增强作用,结合TEM对这种增强作用进行研究,发现银颗粒的团聚对这种增强作用有减弱作用。     

石墨烯携载无机纳米粒子的制备及拉曼性能研究

通过原位复合的方法,在石墨烯片层间掺杂纳米银颗粒,制备出石墨烯/银纳米杂化材料(RGO/Ag)。利用紫外吸收光谱、傅里叶红外光谱、透射电子显微镜(TEM)、XRD、拉曼光谱等对氧化石墨烯(GO)、还原氧化石墨烯(RGO)和石墨烯/银纳米杂化材料(RGO/Ag)进行表征。发现复合材料中的银对石墨烯/银材料有拉曼增强作用,结合TEM对这种增强作用进行研究,发现银颗粒的团聚对这种增强作用有减弱作用。     

PANI/煤基石墨烯宏观体复合材料的制备及其电化学性能

以太西无烟煤为原料,采用催化热处理、改良Hummers氧化等方法,制备煤基氧化石墨烯（CGO）,进而以CGO和聚苯胺（PANI）为前驱体,采用水热自组装法,制备得到PANI/石墨烯宏观体复合材料（3D-PCG）。采用FT-IR、XRD、Raman、SEM和TEM等技术,研究了材料的组成、结构和形貌,考察了3D-PCG的电化学性能。结果表明,PANI以纳米棒状形态均匀镶嵌在煤基石墨烯宏观体（3D-CG）的网状结构中;当PANI与CGO质量比为1：2时,3D-PCG的电化学性能优于PANI和3D-CG,其比电容可达663 F·g^-1。     

NiFe_2O_4@TiO_2/RGO光催化剂的制备及催化性能研究

采用水热法成功制备了NiFe_2O_4@TiO_2/RGO纳米复合材料,考察了氧化石墨烯(GO)掺杂量对复合材料晶型、形貌、磁性能、热性能和光吸收性能的影响,并研究了复合材料对甲基橙的光催化降解性能,探讨了降解机理。结果表明,随着GO掺杂量的增加,NiFe_2O_4@TiO_2/RGO的比饱和磁化强度逐渐下降,但依然展示出超顺磁性;掺杂10%GO的NiFe_2O_4@TiO_2/RGO纳米复合材料具有优异的光吸收性能,紫外光照射90 min,其对甲基橙的脱色率达到98%。NiFe_2O_4@TiO_2/RGO纳米复合材料是性能优异的可回收光催化剂。     

RGO/BaTiO_3复合材料的制备与性能研究

采用改进的Hummer法制备氧化石墨烯(GO),以乙二醇为还原剂将GO还原得到RGO(Reduced graphene oxide),并通过物理共混法制备RGO/BaTiO3复合材料。采用扫描电镜、X射线衍射、傅里叶红外、介电性能测试仪等对其表面形貌、微观结构、介电性能进行了表征。结果表明,乙二醇为还原剂成功实现了GO的还原,且还原后的RGO有效提高了RGO/BaTiO3复合材料的介电性能。当RGO质量分数为0. 5%～0. 8%时,复合材料的介电常数高达140以上,比纯BaTiO3材料提高约1. 75倍,且介电损耗控制在0. 2～0. 45之间。     

In-situ polymerization and characteristic properties of the waterborne poly(siloxanes-urethane)s nanocomposites containing graphene

In this study, graphene oxide (GO) was chemically reduced into reduced GO (RGO) by using hydrazine and a series of waterborne RGO/poly(siloxane-urethane) (SWPU) nanocomposites with various amounts of RGO were synthesized through in-situ polymerization. Siloxane units were incorporated into the nanocomposites to cause the cross-linking reaction in polyurethane (PU) units. Changes in the structure of the nanocomposites were examined through X-ray diffractometry (XRD). The results revealed two broad peaks at 2θ?=?10° and 20°, indicating the existence of short-range ordering in the hard domains. The relative intensities of the two XRD peaks varied with the RGO content orderly. Additionally, thermogravimetric analysis, dynamic mechanical analysis, tensile testing, hardness measurement, and thermal conductivity analysis were conducted to investigate the thermal and mechanical properties of the nanocomposites. The results suggest that the thermal decomposition temperature (Td), dynamic glass transition temperature (Tgd), tensile strength, and Young’s modulus were at their optimal levels with 0.3 wt% of RGO, and an RGO amount greater than 0.3 wt% weakened the thermal and mechanical properties of the nanocomposites. The surface morphology of the nanocomposites was determined using a scanning electron microscope, atomic-force microscope and contact angle meter. The results suggest that surface roughness and contact angle increased considerably with RGO content. In addition, the electrical and thermal conductivities of the nanocomposites increased with increasing RGO content.     

Characterization and performance of dodecyl amine functionalized graphene oxide and dodecyl amine functionalized graphene/high‐density polyethylene nanocomposites: A comparative study

Dodecyl amine (DA) functionalized graphene oxide(DA‐GO) and dodecyl amine functionalized reduced graphene oxide (DA‐RGO) were produced by using amidation reaction and chemical reduction, then two kinds of well dispersed DA‐GO/high‐density polyethylene (HDPE) and DA‐RGO/HDPE nanocomposites were prepared by solution mixing method and hot‐pressing process. Thermogravimetric, X‐ray photoelectron spectroscopy, Fourier transforms infrared spectroscopy, X‐ray diffractions, and Raman spectroscopy analyses showed that DA was successfully grafted onto the graphene oxide surface by uncleophilic substitution and the amidation reaction, which increased the intragallery spacing of graphite oxide, resulting in the uniform dispersion of DA‐GO and DA‐RGO in the nonpolar xylene solvent. Morphological analysis of nanocomposites showed that both DA‐GO and DA‐RGO were homogeneously dispersed in HDPE matrix and formed strong interfacial interaction. Although the crystallinity, dynamic mechanical, gas barrier, and thermal stability properties of HDPE were significantly improved by addition of small amount of DA‐GO or DA‐RGO, the performance comparison of DA‐GO/HDPE and DA‐RGO/HDPE nanocomposites indicated that the reduction of DA‐GO was not necessary because the interfacial adhesion and aspect ratio of graphene sheets had hardly changed after reduction, which resulting in almost the same properties between DA‐GO/HDPE and DA‐RGO/HDPE nanocomposites. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39803.     

Strategically designed reduced graphene oxide based magnetic responsive nanocatalysts for the attenuation of recalcitrant pollutants

The present work attempts to capture the augmentation in the catalytic activity of ferrite (MFe₂O₄) nanoparticles by employing reduced graphene oxide (RGO) as its solid support that not only provides space for dispersion but also increases the catalytically active sites of nanoferrites. MFe₂O₄/xRGO (M = Co, Ni and x = 0, 10, 20, 30, 40 wt% GO) were prepared via facile hydrothermal method and their physical characteristics were probed by FT-IR, XRD, FE-SEM, HR-TEM, VSM and BET analysis. Furthermore, the fabricated samples were explored as versatile catalysts for the remediation of hazardous environmental pollutants via oxidation of a cationic dye, an anionic dye and an antibiotic; and reduction of 2-, 3- and 4-nitrophenol. The catalytic behavior of MFe₂O₄/xRGO was found to be dependent on presence of RGO as solid support as well as on the amount of GO added. The synergistic interaction between dispersed ferrite nanoparticles and RGO sheet was the reason behind the superior catalytic activity of RGO supported nanoferrites in comparison with pure nanoferrites, whereas the increase in specific surface area accounted for augmented activity with increased GO content. High reaction rates were observed even in the absence of light irradiation using MFe₂O₄/RGO nanocomposites for oxidation reactions. However, for the reduction of nitrophenols, the introduction of RGO resulted in the transformation of inactive CoFe₂O₄ into highly active catalysts. Also, the usage of just 2 mol% of RGO supported nanoferrites gave astonishing reduction rates. Moreover, the nanocomposites manifested excellent recyclability furthering the humanitarian cause to remove environmental pollutants.     

Microwave irradiation synthesis and characterization of RGO‐AgNPs/polystyrene nanocomposites

Polystyrene and reduced graphene oxide/silver (PSTY/RGO/AgNPs) nanocomposites were prepared via an in situ bulk polymerization method using two different preparation techniques. In the first approach, a mixture of silver nitrate, hydrazine hydrate, and polystyrene containing graphene oxide (PSTY/GO) were reduced by microwave irradiation (MWI) to obtain R‐(PSTY‐GO)/AgNPs nanocomposites. In the second approach, a mixture of the (RGO/AgNPs) nanocomposite, which was produced via MWI, and STY monomers were polymerized using an in situ bulk polymerization method to obtain PSTY‐RGO/AgNPs nanocomposites. The two nanocomposites were compared and characterized by Fourier transform infrared spectroscopy, X‐ray diffraction, X‐ray photoelectron spectroscopy, high‐resolution transmission electron microscopy, Differential scanning calorimetry, and thermogravimetric analysis. The results indicate that the nanocomposites obtained using the first approach, which involved MWI, exhibited a better morphology and dispersion with enhanced thermal stability compared to the nanocomposites prepared without MWI. POLYM. COMPOS., 35:2318–2323, 2014. © 2014 Society of Plastics Engineers     

Dielectric and dye adsorption properties of luminescent-superparamagnetic MFe2O4 (M = Mn,Mg)/reduced graphene oxide composites

MFe₂O₄ (M = Mn, Mg)/reduced graphene oxide (MFe₂O₄/RGO) nanocomposites were synthesized through a simple and novel pressure cooker assisted solvothermal method. The nanocomposites were characterized using x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV–Vis absorption and photoluminescence spectroscopy, transmission electron microscopy (TEM) and x-ray photoelectron spectroscopy (XPS). The optical analyses showed that, the MFe₂O₄/RGO materials have good photoluminescence (PL) with excitation dependent PL properties while magnetic characterization indicated that, the as-synthesized MFe₂O₄/RGO nanocomposites exhibits superparamagnetic behavior. Dielectric spectroscopy analysis showed enhanced dielectric constant, dielectric loss and AC conductivity for MFe₂O₄/RGO, compared to graphite oxide (GO). The study on methyl blue (MB) dye adsorption revealed that, the as-prepared nanocomposites have strong and recyclable adsorption for MB.     

In situ green synthesis of Ag nanoparticles on graphene oxide/TiO2 nanocomposite and their catalytic activity for the reduction of 4-nitrophenol,congo red and methylene blue

The Ag/RGO/TiO₂ nanocomposite was synthesized through an environmentally benign, simple, cost efficient, surfactant-free and green method using Euphorbia helioscopia L. leaf extract as a stabilizing and reducing agent. The E. helioscopia L. leaf extract was used for the reduction of Ag⁺ ions and GO to Ag NPs and RGO, respectively. The GO/TiO₂ and Ag/RGO/TiO₂ nanocomposites were characterized by FT-IR, UV–vis, TEM, XRD, SEM, EDS and ICP techniques. The Ag/RGO/TiO₂ nanocomposite was highly active for the reduction of 4-nitrophenol (4-NP), congo red (CR) and methylene blue (MB) in aqueous media at an ambient temperature. The Ag/RGO/TiO₂ nanocomposite was easily separated and recovered from the reaction mixture by centrifugation and reused for several cycles without any significant loss of catalytic activity.     

Influence of graphene-based compounds on the mechanical toughness and thermal stability of polypropylene

A study of the improvement of the mechanical and thermal properties of nanocomposites prepared with polypropylene (PP) and different graphene samples [graphene oxide (GO), reduced GO (RGO), and commercial graphene (G)] is presented. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy characterization were applied to the graphene samples. The nanocomposites were characterized by thermogravimetric analysis, XRD, differential scanning calorimetry, transmission electron microscopy (TEM), tensile, and impact resistance tests. PP/RGO nanocomposites showed significant improvement in mechanical and thermal properties. Sample PP/RGO-0.75 resulted in an increment in Young's modulus (51%), tensile strength (24%), and elongation at break (15%). This is attributed to a good dispersion state, a higher crystallinity percentage, and a good interfacial adhesion between PP and RGO. Sample PP/RGO-0.50 exhibited an increase of 197 °C in the temperature at which a loss in weight of 5% occurred, compared to that for pure PP. The height of stacked layers calculated by XRD measurements was similar to the value observed by TEM. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48258.     

Thermal,electrical, and dielectric properties of reduced graphene oxide–polyaniline nanotubes hybrid nanocomposites synthesized by in situ reduction and varying graphene oxide concentration

In this study, reduced graphene oxide (RGO) has been introduced as conductive filler within polyaniline (PAni) nanotubes (PAniNTs) by in situ chemical reduction method to enhance the properties of PAniNTs. The effect of varied concentration of in situ reduced GO on the structural, thermal, electrical, and dielectric properties of RGO–PAniNTs nanocomposites have been investigated by high resolution transmission electron microscope, X‐ray diffraction, Fourier transform infrared, thermogravimetric analysis, I–V characteristics, and impedance analyzer. The enhanced thermal stability of the nanocomposites has been analyzed from the derivative thermogravimetric curves in terms of onset and rapid decomposition temperature. The transport mechanisms have been studied by fitting the nonlinear I–V characteristics to the Kaiser model. The dielectric relaxation phenomena have been investigated by permittivity and modulus formalisms. Characteristic relaxation frequency of RGO–PAniNTs nanocomposites shifts toward higher frequency with increasing RGO concentration indicating a distribution in conductivity relaxation. The distribution of relaxation time has been studied by fitting the imaginary modulus spectra of the nanocomposites to Bergman modified KWW function. The ac conductivity spectra are fitted to the Jonscher's power law equation and enhanced conductivity value of 1.26 × 10⁻³ S cm⁻¹ is obtained for 40 wt % of RGO compared to 1.22 × 10⁻⁴ S cm⁻¹ for PAniNTs. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45883.     

One pot preparation of reduced graphene oxide (RGO) or Au (Ag) nanoparticle-RGO hybrids using chitosan as a reducing and stabilizing agent and their use in methanol electrooxidation

An environment-friendly approach to synthesizing reduced graphene oxide (RGO) was developed by using chitosan (CS) as both a reducing and a stabilizing agent. Factors that affect the reduction of graphene oxide (GO), such as the ratio of CS/GO, pH and temperature, were explored to obtain optimum reaction conditions. The RGO was characterized with UV visible absorption spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction spectroscopy, thermo-gravimetric analysis, and X-ray photoelectron spectroscopy and transmission electron microscopy. Analysis shows that CS macromolecules can efficiently reduce GO at a comparatively low temperature and their adsorption onto the RGO nanosheets allows a stable RGO aqueous dispersion to be formed. Since CS is a natural, nontoxic and biodegradable macromolecule, this approach provides a new green method for GO reduction that would facilitate the large scale production of RGO, which has great value for graphene applications. Moreover, CS can reduce GO and AgNO₃ (or HAuCl₄) in one pot to obtain Ag nanoparticle-RGO hybrids or Au nanoparticle-RGO hybrids that exhibit good electrochemical activity.     

Synthesis of butterfly-like BiVO4/RGO nanocomposites and their photocatalytic activities

A simple and high efficient method was proposed for the synthesis of uniform three dimensional(3D) BiVO_4/reduced graphene oxide(RGO) nanocomposite photocatalyst by adopting the microwave assistant and using Bi(NO_3)_3·5H_2O, graphene oxide(GO) and NH_4VO_3 as precursor. The as-obtained composites were well characterized with the aid of various techniques to study the morphology, structure, composition, optimal and electrical property. In the as-obtained composites, the GO sheets were fully reduced into RGO, and monoclinic structure BiVO_4 crystallized completely into butterfly-like BiVO_4 lamellas and well bonded with the RGO lamellas. The length and the width of the butterfly-like BiVO_4 particle were about 1.5 μm, and the thickness of the flake was about 20 nm. Photocatalytic performances of BiVO_4/RGO composite and pure BiVO_4 particle have been evaluated by investigating the reduction of Cr(Ⅵ) ion-contained wastewater under simulated solar light irradiation, where the BiVO_4/RGO composite displayed enhanced photocatalytic activity. It is found that the pseudo-first-order rate constants(k) for the photocatalytic reduction of Cr(VI) by BiVO_4/RGO composite was about 4 times as high as that of the pure BiVO_4. The present work suggested that the combination of BiVO_4 and RGO displayed a remarkable synergistic effect, which led to enhanced photo-catalytic activity on Cr(Ⅵ) reduction.