Graphene Oxide (GO) as Stabilizer for Preparing Chirally Helical Polyacetylene/GO Hybrid Microspheres via Suspension Polymerization

Hybrid materials consisting of polymers and graphene are gathering ever‐growing interest. This article reports a novel methodology for preparing chirally helical polyacetylene/graphene hybrid microspheres (MPs) via suspension polymerization in which graphene oxide (GO) or alkynylated GO (M GO) serves as a sole stabilizer. Such polymerizations show remarkable advantages in circumventing the difficulties in usual suspension polymerizations and especially in directly providing clean hybrid MPs. Scanning electron microscopy (SEM), Raman spectra, and electron dispersive spectroscopy indicate that graphene sheets cover the MPs through physical interaction (GO) or covalent bonds (M GO). The hybrid MPs are also characterized by Fourier‐transform infrared spectroscopy (FT‐IR), X‐ray photoelectron spectroscopy, and thermogravimetric analysis. Circular dichroism spectra demonstrate that the polymer chains constituting the MPs adopt predominantly one‐handed helices, endowing the MPs with intriguing optical activity. The established strategy opens a new approach for preparing hybrid MPs constructed by acetylenic polymers and GO.     

Photovoltaic properties of graphene oxide sheets beaded with ZnO nanoparticles

A hybrid material of graphene oxide (GO) sheets beaded with ZnO nanoparticles was prepared. The material extends over a few hundred square nanometers, in which the ZnO nanoparticles (average diameter (∼5 nm)) are dispersed evenly on the GO sheet. Both the surface photovoltage or surface photocurrent intensity for the material are much stronger than for pure ZnO nanoparticles, meaning that the free charge carriers can effectively be transferred from ZnO nanoparticles to GO sheets, which can serve as a probe to monitor the electron transfer from excited ZnO to GO. Anchoring ZnO nanoparticles on two dimensional carbon nanostructures such as GO can pave a way towards the design of ordered nanostructure assemblies that can harvest light energy efficiently.     

Date Fruits-Assisted Synthesis and Biocompatibility Assessment of Nickel Oxide Nanoparticles Anchored onto Graphene Sheets for Biomedical Applications

Nanographene- and graphene-based nanohybrids have garnered attention in the biomedical community owing to their biocompatibility, excellent aqueous processability, ease of cellular uptake, facile surface functionalization, and thermal and electrical conductivities. NiO nanoparticle-graphene nanohybrid (G-NiO) was synthesized by first depositing Ni(OH)₂ onto the surface of graphene oxide (GO) sheets. The Ni(OH)₂-GO hybrids were then reduced to G-NiO using date palm syrup at 85 °C. The prepared G-NiO nanohybrids were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy, and energy-dispersive X-ray spectroscopy (EDX). The NiO nanoparticles, with a diameter of approximately 20–30 nm, were uniformly dispersed over the surface of the graphene sheets. The G-NiO hybrids exhibit biocompatibility in human mesenchymal stem cells (hMSCs) up to 100 μg/mL. The nanohybrids do not cause any significant changes in cellular and nuclear morphologies in hMSCs. The as-synthesized nanohybrids show excellent biocompatibility and could be a promising material for biomedical applications.     

Preparation of Nanoscrolls by Rolling up Graphene Oxide–Polydopamine–Au Sheets using Lyophilization Method

Graphene oxide–polydopamine–Au (GO–PDA–Au) nanoscrolls were prepared by rolling up GO–PDA–Au sheets through a simple lyophilization method. The structure of GO–PDA–Au nanoscrolls and GO–PDA–Au sheets were compared by powder X‐ray diffraction, Raman spectra, transmission electron microscopy, and scanning electron microscopy. The results demonstrated that the heterogeneous GO–PDA–Au nanoscrolls were synthesized successfully. Polydopamine (PDA) attached at the surface of GO sheets served as binding reagents to anchor and disperse Au nanoparticles (NPs). The electrocatalytic activity of methanol with GO–PDA–Au nanoscrolls and GO–PDA–Au sheets as electrodes were conducted. Compared to GO–PDA–Au sheets, GO–PDA–Au nanoscrolls showed better electrocatalytic activity and electrochemical stability owing to their scrolled structure. This article provides a simple and effective method to prepare GO nanoscrolls containing metal NPs that broadens the applications of the graphene‐based materials in optical, magnetic, and catalytic fields.     

Activated carbon/graphene composites with high-rate performance as electrode materials for electrochemical capacitors

Glucose-derived activated carbon (GAC)/reduced graphene oxide (RGO) composites are prepared by pre-carbonization of the precursors (aqueous mixture of glucose and graphene oxide) and KOH activation of the pyrolysis products. The effect of the mass ratio of graphene oxide (GO) in the precursor on the electrochemical performance of GAC/RGO composites as electrode materials for electrochemical capacitors is investigated. It is found that the thermally reduced graphene oxide sheets serves as a wrinkled carrier to support the activated carbon particles after activation. The pore size distribution and surface area are depended on the mass ratio of GO. Besides, the rate capability of GAC is improved by the introduction of GO in the precursor. The highest specific capacitance of 334 F g^?1 is achieved for the GAC/RGO composite prepared from the precursor with a GO mass ratio of 3 %.     

Two step hydrothermal synthesis of flowerbud-like magnetite/graphene oxide hybrid with high-performance microwave absorption

A novel flowerbud-like magnetite/graphene oxide (GO) hybrid was synthesized from facile two-step hydrothermal process by using FeCl₃ as iron source, ethylene glycol as the reducing agent, and graphene oxide as template. The magnetite nanoparticles with the diameters of 70–80 nm were attached onto the surface of graphene oxide through the two-step self-assembly process which enhanced the magnetic properties of the hybrids. The final flowerbud-like magnetite/graphene oxide hybrid emerged with the saturated magnetization of ~84.5 emu g^–1. More importantly, owing to the combined contribution of enhanced dielectric and magnetic properties, the maximum microwave absorption of as-prepared magnetite/GO hybrid reached 30 dB with a thickness of 4 mm. Besides, the absorption bandwidth with a reflection loss above 23 dB ranged from 6.0 to 11.5 GHz.     

Highly Porous Hydroxyapatite/Graphene Oxide/Chitosan Beads as an Efficient Adsorbent for Dyes and Heavy Metal Ions Removal

Dye and heavy metal contaminants are mainly aquatic pollutants. Although many materials and methods have been developed to remove these pollutants from water, effective and cheap materials and methods are still challenging. In this study, highly porous hydroxyapatite/graphene oxide/chitosan beads (HGC) were prepared by a facile one-step method and investigated as efficient adsorbents. The prepared beads showed a high porosity and low bulk density. SEM images indicated that the hydroxyapatite (HA) nanoparticles and graphene oxide (GO) nanosheets were well dispersed on the CTS matrix. FT-IR spectra confirmed good incorporation of the three components. The adsorption behavior of the obtained beads to methylene blue (MB) and copper ions was investigated, including the effect of the contact time, pH medium, dye/metal ion initial concentration, and recycle ability. The HGC beads showed rapid adsorption, high capacity, and easy separation and reused due to the porous characteristics of GO sheets and HA nanoparticles as well as the rich negative charges of the chitosan (CTS) matrix. The maximum sorption capacities of the HGC beads were 99.00 and 256.41 mg g⁻¹ for MB and copper ions removal, respectively.     

Preparation of an Anti-Aggregation Silica/Zinc/Graphene Oxide Nanocomposite with Enhanced Adsorption Capacity

Nanomaterials play a significant role in adsorption treatment of dye wastewater, but irreversible aggregation of nanoparticles poses a significant problem. In this work, nanomesoporous zinc-doped silicate (NMSZ) was prepared by an in situ method. To prevent agglomeration, NMSZ was covalently bonded to graphene oxide (GO) sheets to form a nano-silica/zinc/graphene oxide composite (GO-NMSZ), aimed at removal of cationic dye methylene blue (MB). For comparison, undoped mesoporous silica (MS) was also synthesized and modified to obtain a silica/graphene oxide composite (GO-MS). The materials were characterized by powder XRD, SEM, FTIR spectroscopy, TEM, nitrogen sorption, and X-ray photoelectron spectroscopy (XPS). Preservation of the oxygen-containing groups of GO in the composites led to higher adsorption capacities. The best GO-NMSZ composite exhibited an enhanced adsorption capacity of 100.4 mg g⁻¹ for MB compared to those of undoped GO-MS (80.1 mg g⁻¹) and nongrafted NMSZ (55.7 mg g⁻¹). The nonselective character of GO-NMSZ is demonstrated by effective adsorption of anionic dye Congo red (127.4 mg g⁻¹) and neutral dye isatin (289.0 mg g⁻¹). The adsorption kinetics, adsorption isotherms, and a thermodynamic study suggested that MB adsorption occurs by chemisorption and is endothermic in nature.     

Facile fabrication of self-assembled PMMA/graphene oxide composite particles and their electroresponsive properties

Core–shell-structured poly(methyl methacrylate) (PMMA)/graphene oxide (GO) composite particles were prepared using a facile process, in which GO was adsorbed spontaneously onto a microspherical PMMA surface when hydrophobic microspheres were dispersed in deionized (DI) water stabilized by amphiphilic GO under ultrasonication. The fabricated composite was characterized by SEM, TEM, FT-IR, and thermogravimetric analysis. Results showed that the particle surface could be wrapped with GO without the need for surfactants. In addition, electrorheological behavior of the chain-forming process of the PMMA/GO composite particles was observed by optical microscopy under an applied electric field. Both shear stress and shear viscosity related to the strength of the applied electric field were measured using a rotational rheometer. The proposed Cho–Choi–Jhon model was used to describe their ER performances for the entire shear rate region. Moreover, the response of the shear stress to an imposed square voltage at a fixed shear rate was also examined.     

Free‐standing Graphene/Poly(methylene blue)/AgNPs Composite Paper for Electrochemical Sensing of NADH

Highly flexible graphene/poly(methylene blue)/AgNPs composite paper was successfully prepared for amperometric biosensing of NADH. For this purpose, a dispersion including graphene oxide (GO), methylene blue (MB) and silver nanoparticles (AgNPs) was prepared and GO/MB/AgNPs paper was acquired by vacuum‐filtration of this dispersion through a suitable membrane. After peeling it off from membrane, it was transformed to rGO/MB/AgNPs paper by performing reduction with hydriodic acid. In a three‐electrode cell, which is containing 0.1 M phosphate buffer solution (pH: 9.0), rGO/MB/AgNPs paper was used as working electrode and rGO/poly(MB)/AgNPs composite paper was generated by surface‐confined electropolymerization of MB using successive cyclic voltammetry approach in a suitable potential window. Characterization of this composite paper was carried out by using scanning electron microscopy, scanning tunneling microscopy, X‐ray photoelectron spectroscopy, powder X‐ray diffraction spectroscopy, Raman spectroscopy, four‐point probe conductivity measurement and cyclic voltammetry techniques. Flexible rGO/poly(MB)/AgNPs composite paper has demonstrated high sensitivity, wide linear range and low detection limit for amperometric quantification of NADH.     

磁性壳聚糖/Fe3O4/氧化石墨烯吸附剂的制备及其多染料吸附性能

为了提高壳聚糖的多染料吸附性能并使其便于固液分离,采用共沉淀法制备了壳聚糖、磁铁矿纳米颗粒、氧化石墨烯复合磁性吸附剂(CS/Fe₃O₄/GO)。系统的结构表征显示,CS包覆的Fe₃O₄磁性纳米颗粒均匀地分布在GO的表面。CS/Fe₃O₄/GO具有高达42.5 emu·g-1的室温铁磁性,因此可在外加磁场中实现高效固液分离。研究表明,CS/Fe₃O₄/GO对亚甲基蓝(MB)、甲基橙(MO)和刚果红(CR)等多种染料具有良好的吸附性能,溶液的pH、初始浓度和吸附时间对其多染料吸附性能具有显著影响。在最佳条件下,CS/Fe₃O₄/GO对MB、MO和CR的吸附量分别达到210.6、258.6和308.9 mg·g-1。CS/Fe₃O₄/GO具有优异的循环利用性能,经5次循环后仍能保留90%以上的原始吸附量。采用吸附等温线和吸附动力学对...     

Preparation of a novel Fe3O4/graphene oxide hybrid for adsorptive removal of methylene blue from water

In this work, a novel Fe₃O₄/graphene oxide (GO) hybrid was prepared and its removal ability of cationic methylene blue dye from water was investigated. To improve the dispersability of Fe₃O₄/GO hybrid in water, GO was first modified by polyethylene glycol (PEG) via a click approach before deposition of Fe₃O₄ nanoparticles onto its surface. The successful modification of GO surface and the deposition of Fe₃O₄ nanoparticles were confirmed by transmission electron microscopy directly. The saturation magnetization of the resultant Fe₃O₄/GO hybrid is 7.8 eum/g. The adsorption capacities of Fe₃O₄/GO hybrid for methylene blue at 35 and 60°C were as high as 96.05 and 120.05 mg/g, respectively. Moreover, the Langmuir, Freundlich, and Temkin models are used to investigate the isothermal adsorption behavior of Fe₃O₄/GO hybrid.     

Sensitive determination of the endocrine disruptor bisphenol A at ultrathin film based on nanostructured hybrid material SiO<Subscript>2</Subscript>/GO/AgNP

In this work, we described an electrochemical sensor using a nanocomposite based on graphene oxide (GO), silver nanoparticles (AgNP), and disordered mesoporous silica (SiO₂), which was used for the determination of bisphenol A in water samples. Initially, the hybrid material SiO₂/GO was synthesized via sol-gel process, subsequently decorated with AgNP with an approximate 20 nm particle size prepared directly on the surface of the SiO₂/GO using N, N-dimethylformamide (DMF) as an agent reducer. A glassy carbon electrode was modified with SiO₂/GO/AgNP and used in developing a sensitive electrochemical sensor for the determination of bisphenol A in phosphate buffer 0.1 mol L^?1 (pH 7.0). The detection limit was 45.2 nmol L^?1 with a linear response range between 1.0 × 10^?7 and 2.6 × 10^?6 mol L^?1 and a sensitivity of 1.27 × 10^?7 A mol^?1 L. Finally, the optimized electrochemical sensor was used for the quantitation of endocrine interfering in natural waters.     

High stability silver nanoparticles–graphene/poly(ionic liquid)-based chemoresistive sensors for volatile organic compounds’ detection

Hybrids of silver nanoparticle-decorated reduced graphene oxide (Ag-RGO) have been prepared with the use of poly(ionic liquid) (PIL) as a versatile capping agent to develop volatile organic compound (VOC) sensors. The hybrid materials of Ag-RGO/PIL were assembled into three-dimensional-laminated nanostructures, where spherical Ag nanoparticles with diameters between 50 and 300 nm were homogeneously distributed on the graphene sheets and interspaced between them. Ag-RGO/PIL sensors were fabricated by spray layer-by-layer technique and used to detect a set of polar (methanol, ethanol, methyl acetate, acetone and water) and non-polar (chloroform, dichlorobenzene, toluene and styrene) organic vapours. Much higher sensitivity and discriminability were obtained for polar vapours although non-polar ones could also be detected. In comparison with either simple reduced graphene oxide or carbon nanotubes (CNT) functionalised by PIL, the hybrid Ag-RGO/PIL-based sensors showed superior performances in terms of sensitivity, selectivity, stability and high reliability. For example, a signal-to-noise ratio up to 168 was obtained for 1 ppm of methanol and signals drift between two experiments spaced out in the time of 3 months was less than 3 %. It is expected that by extrapolation, a limit of detection at the parts per billion level can be reached. These results are promising to design e-noses based on high stability chemoresistive sensors for emerging applications such as anticipated diagnostic of food degradation or diseases by the analysis of VOC, some of them being in this case considered as biomarkers.     

High solar-light photocatalytic activity of using Cu3Se2/rGO nanocomposites synthesized by a green co-precipitation method

Current work presents a facile, cost-effective, and green method to synthesize copper selenide nanostructures and copper selenide/graphene nanocomposites. The products were synthesized by a co-precipitation method by glycine amino acid as a green surfactant and graphene oxide (GO) sheets as a graphene source. X-ray diffraction patterns (XRD) of the products indicated that the products were Cu₂Se₃ with tetragonal phase. Fourier transform infrared (FTIR) spectroscopy and the XRD patterns indicated that the GO sheets were changed into reduced GO (rGO) during the synthesis process. Scanning and transmission electron microscopy (SEM and TEM) images showed the nanoparticles (NPs) that were decorated on rGO sheets had the significantly smaller size in compared to the pristine NPs. UV-vis results revealed that, the absorption peak of the products were in the visible region with a band-gap value between 1.85 eV and 1.95 eV. Finally, the products were applied as photocatalytic materials to remove Methylene Blue (MB) dye under solar-light and visible-light irradiation conditions. It was observed; the rGO had a significant role in enhancing the photocatalytic performance of the products and Cu₂Se₃/rGO (15%) could degrade more than 91% and 73% of MB only during 1 h under solar-light and visible-light sources, respectively.     

Wrapping Nanocellulose Nets around Graphene Oxide Sheets

Constructing advanced functional nanomaterials with pre‐designed organized morphologies from low‐dimension synthetic and biological components is challenging. Herein, we report an efficient and universal amphiphilicity‐driven assembly strategy to construct “hairy” flexible hybrid nanosheets with a 1D cellulose nanofibers (CNFs) net conformally wrapped around 2D graphene oxide (GO) monolayers. This interface‐driven bio‐synthetic assembly is facilitated by tailoring the surface chemistry of flexible GO sheets, resulting in individual sheets tightly surrounded by dense conformal nanocellulose network. The mechanical stability of the products far exceeds the compressive instability limits of both individual components. Additionally, the CNF network significantly enhances the wetting ability of initial hydrophobic reduced GO nanosheets, allowing fast water transport combined with high filtration efficiency.     

石墨烯/银复合薄膜的制备及表征

采用静电自组装技术,通过交替沉积聚(二烯丙基二甲基氯化铵)(PDDA)(或硝酸银)和氧化石墨烯,制备氧化石墨烯/PDDA薄膜和氧化石墨烯/硝酸银复合薄膜。然后在600℃下通入氩气和氢气进行气氛还原得到石墨烯薄膜和石墨烯/银复合薄膜。采用AFM、SEM、XPS、UV-Vis以及四探针电阻仪等对薄膜结构及性质进行表征。结果表明,通过静电自组装法可以获得生长均匀的薄膜。对比于相同自组装次数的石墨烯薄膜,石墨烯/银复合薄膜具有更好的透光性和更低的薄膜方块电阻。在λ=500 nm时,四层石墨烯/银复合薄膜的透过率为85%左右,而石墨烯薄膜的透过率为72%左右;石墨烯薄膜的方阻为161.39 kΩ.□-1,而石墨烯/银复合薄膜的方阻为99.11 kΩ.□-1。     

Preparation of ZnO/GO composite material with highly photocatalytic performance via an improved two-step method

ZnO/graphene oxide(ZnO/GO) composite material,in which ZnO nanoparticles were densely coated on the GO nanosheets,was successfully prepared by an improved two-step method and characterized by IR, XRD,TEM,and UV-vis techniques.The improved photocatalytic property of the ZnO/GO composite material,evaluated by the photocatalytic degradation of methyl orange(MO) under UV irradiation,is ascribed to the intimate contact between ZnO and GO,the enhanced adsorption of MO,the quick electron transfer from excited ZnO particles to GO sheets and the activation of MO molecules viaπ-πinteraction between MO and GO.     

Reduced graphene oxide as capturer of dyes and electrons during photocatalysis: surface wrapping and capture promoted efficiency

To elucidate the roles of graphene in photoelectric events and mass transfer during photocatalytic process is important for engineering graphene-semiconductor hybrid photocatalyst. Here, we demonstrated reduced graphene oxide (RGO) capturing dyes and photoinduced electrons during photocatalytic degradation of organic dyes in water. It captures dyes from water through adsorption and desorption irreversible hysteresis, and captures photoinduced electrons from semiconductor through surface junction. The RGO was attached to the surface of TiO(2) in the form of surface wrapping. After one-step photocatalytic reduction of graphene oxide (GO) and TiO(2) in ethanol-water solvent under UV irradiation, the RGO wrapped TiO(2) hybrid (graphene-w-TiO(2)) photocatalyst was obtained. Using visible absorption spectroscopy, we also demonstrated these captured dyes were degraded during photocatalysis. The photocatalytic test showed the RGO significantly improved the photocatalytic activity of this hybrid photocatalyst.     

磁性壳聚糖/Fe3O4/氧化石墨烯吸附剂的制备及其多染料吸附性能

为了提高壳聚糖的多染料吸附性能并使其便于固液分离,采用共沉淀法制备了壳聚糖、磁铁矿纳米颗粒、氧化石墨烯复合磁性吸附剂(CS/Fe₃O₄/GO)。系统的结构表征显示,CS包覆的Fe₃O₄磁性纳米颗粒均匀地分布在GO的表面。CS/Fe₃O₄/GO具有高达42.5 emu·g^-1的室温铁磁性,因此可在外加磁场中实现高效固液分离。研究表明,CS/Fe₃O₄/GO对亚甲基蓝(MB)、甲基橙(MO)和刚果红(CR)等多种染料具有良好的吸附性能,溶液的pH、初始浓度和吸附时间对其多染料吸附性能具有显著影响。在最佳条件下,CS/Fe₃O₄/GO对MB、MO和CR的吸附量分别达到210.6、258.6和308.9 mg·g^-1。CS/Fe₃O₄/GO具有优异的循环利用性能,经5次循环后仍能保留90%以上的原始吸附量。采用吸附等温线和吸附动力学对CS/Fe₃O₄/GO的多染料吸附性能进行了拟合分析,并详细讨论了其吸附机理。