Controllable synthesis, magnetism and solubility enhancement of graphene nanosheets/magnetite hybrid material by covalent bonding

Hybrids of Fe(3)O(4) nanoparticles and surface-modified graphene nanosheets (GNs) were synthesized by a two-step process. First, graphene nanosheets were modified by SOCl(2) and 4-aminophenoxyphthalonitrile to introduce nitrile groups on their surface. Second, the nitrile groups of surface-modified graphene nanosheets were reacted with ferric ions on the surface of Fe(3)O(4) with the help of relatively high boiling point solvent ethylene glycol to form a GNs/Fe(3)O(4) hybrid. The covalent attachment of Fe(3)O(4) nanoparticles on the graphene nanosheet surface was confirmed by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy-dispersive X-ray spectrometer (EDS) and scanning electron microscopy (SEM). TEM and HRTEM observations indicated that the sizes of the nanoparticles and their coverage density on GNs could be easily controlled by changing the concentration of the precursor and the weight ratio to GNs. Magnetic measurements showed that magnetization of the hybrid materials is strongly influenced by the reaction conditions. Chemically bonded by phthalocyanine, the solubility of as-synthesized GNs/Fe(3)O(4) hybrid materials was greatly enhanced, which was believed to have potential for applications in the fields of composites, wastewater treatment and biomaterials.     

聚苯胺/H2W2O7层状复合材料的制备研究

以层状钨基氧化物(H2W2O7)为无机主体, 用正庚胺改性后的正庚胺/H2W2O7复合物(HTT)为中间体, 通过离子交换、层间O2引发聚合等步骤成功制备了聚苯胺/H2W2O7层状复合材料(PANI/H2W2O7). X射线衍射、扫描电子显微镜、红外光谱及差热分析结果表明: 聚苯胺分子已成功地嵌入H2W2O7层间, 层状结构没被破坏, 层间距变至1.19 nm; 聚苯胺的嵌入还大大提高了材料的热稳定性. 讨论了无机主体与有机客体之间的相互作用、聚苯胺在层间的排布形式及苯胺和聚苯胺插入层间的反应机理.     

Controllable synthesis of organic-inorganic hybrid MoOx/polyaniline nanowires and nanotubes

A novel chemical oxidative polymerization approach has been proposed for the controllable preparation of organic-inorganic hybrid MoO(x)/polyaniline (PANI) nanocomposites based on the nanowire precursor of Mo(3)O(10)(C(6)H(8)N)(2)·2H(2)O with sub-nanometer periodic structures. The nanotubes, nanowires, and rambutan-like nanoparticles of MoO(x)/PANI were successfully obtained through simply modulating the pH values to 2.5-3.5, ≈2.0 and ≈1.0, respectively. Through systematic physicochemical characterization, such as scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and so forth, the composition and structure of MoO(x)/PANI hybrid nanocomposites are well confirmed. It is found that the nanowire morphology of the precursor is the key to achieve the one-dimensional (1D) structures of final products. A new polymerization-dissolution mechanism is proposed to explain the formation of such products with different morphologies, in which the match between polymerization and dissolution processes of the precursor plays the important role. This approach will find a new way to controllably prepare various organic-inorganic hybrid 1D nanomaterials especially for polymer-hybrid nanostructures.     

石墨烯载Pt纳米粒子的原位还原制备及氧还原电催化性能

采用改进的化学氧化还原法(Hummers法)氧化鳞片石墨, 再超声振荡剥离得到氧化石墨烯(GO)水溶液. 通过聚二烯丙基二甲基氯化铵(PDDA)分子对GO表面功能化, 由于带正电荷的PDDA分子功能化的GO与带负电荷的^2-离子间的静电作用, 使Pt离子组装到GO表面, 再通过原位还原被束缚的Pt离子, 同时GO被还原成石墨烯片(GNs), 得Pt/PDDA-GNs催化剂. 相对空白GNs负载的Pt纳米粒子和商业化Pt/C(JM), Pt/PDDA-GNs催化剂有较高的氧还原活性和稳定性. 前者可归因于Pt颗粒尺寸细小和分散度较高, 后者是由于PDDA分子与Pt原子间的电子作用及对Pt颗粒的钉扎作用, 从而减缓了Pt的氧化和迁移.     

Ionic liquid–graphene hybrid nanosheets-based electrochemical sensor for sensitive detection of methyl parathion

In this work, ionic liquid–graphene nanosheets (IL–GNs) were synthesised and used as an enhanced material for sensitive detection of methyl parathion (MP) by electrochemical method. IL–GNs were characterised by UV–Vis spectroscopy, transmission electron microscopy (TEM), X-ray photo-electron spectroscopy (XPS), Fourier transform Infrared (FT-IR) spectroscopy and Raman spectroscopy, which confirmed that IL was successfully covered on the surface of GNs. Significantly, due to the coupling of excellent properties of GNs and IL, the IL–GNs-modified glassy carbon electrode (IL–GNs/GCE) showed higher signals for MP response than the GNs/GCE and bare GCE. At the IL–GNs/GCE, the peak currents increase linearly with the concentration of MP in the range of 5.3 ng/mL to 2.6 μg/mL with the detection limit of 1.1 ng/mL, which was better than other enzyme-based and enzymeless sensors. The IL–GNs-based electrochemical sensor was also successfully demonstrated for the detection of water sample with satisfactory results. Furthermore, the proposed electrochemical sensor exhibited satisfied stability and reproducibility. The simple sensing platform can be extended to detect other organophosphate pesticide.     

Pt微粒修饰纳米纤维聚苯胺电极对甲醇氧化电催化

以脉冲电流法制备的纳米纤维状聚苯胺(PANI)为Pt催化剂载体，用它制备了甲醇阳极氧化的催化电极Pt/（nano-fibular PANI）.研究结果表明, Pt/（nano-fibular PANI）电极对甲醇氧化具有很好的电催化活性,并有协同催化作用.在相同的Pt载量条件下， Pt/（nano-fibular PANI）电极比Pt微粒修饰的颗粒状聚苯胺电极Pt/(granular PANI)具有更好的电催化活性.此外， Pt的电沉积修饰方法同样影响Pt/（nano-fibular PANI）电极对甲醇氧化的催化活性.脉冲电流法沉积Pt形成的复合电极较循环伏安法电沉积得到的Pt复合电极具有更优异的催化活性.     

自支撑三维功能化石墨烯/聚苯胺电极材料的制备及超级电容性能

采用水热法制备了三维石墨烯(3D-G),并以十八胺(ODA)为接枝剂对部分还原的氧化石墨烯进行氨基化处理,再利用原位聚合法在氨基化石墨烯表面生长聚苯胺,制备了十八胺功能化石墨烯/聚苯胺(G-ODA/PANI).对材料进行了结构表征、电化学性能分析和材料结构的比电容贡献分析.结果显示,电极材料的电容贡献大部分体现为材料的表面电容,G-ODA/PANI电极片在1 A/g电流密度时的比电容最高可达1080 F/g,是未功能化石墨烯/聚苯胺电极材料(G/PANI)的2.57倍,且循环稳定性也有很大的提高,循环10000周后的比容量保持率为90.8%,比G/PANI高9.6%.     

Single-layered graphene oxide nanosheet/polyaniline hybrids fabricated through direct molecular exfoliation

In this study, we used direct molecular exfoliation for the rapid, facile, large-scale fabrication of single-layered graphene oxide nanosheets (GOSs). Using macromolecular polyaniline (PANI) as a layered space enlarger, we readily and rapidly synthesized individual GOSs at room temperature through the in situ polymerization of aniline on the 2D GOS platform. The chemically modified GOS platelets formed unique 2D-layered GOS/PANI hybrids, with the PANI nanorods embedded between the GO interlayers and extended over the GO surface. X-ray diffraction revealed that intergallery expansion occurred in the GO basal spacing after the PANI nanorods had anchored and grown onto the surface of the GO layer. Transparent folding GOSs were, therefore, observed in transmission electron microscopy images. GOS/PANI nanohybrids possessing high conductivities and large work functions have the potential for application as electrode materials in optoelectronic devices. Our dispersion/exfoliation methodology is a facile means of preparing individual GOS platelets with high throughput, potentially expanding the applicability of nanographene oxide materials.     

β‐Cyclodextrin‐Platinum Nanoparticles/Graphene Nanohybrids: Enhanced Sensitivity for Electrochemical Detection of Naphthol Isomers

Naphthol isomers, including α‐naphthol (α‐NAP) and β‐naphthol (β‐NAP), are used widely in various fields and are harmful to the environment and human health. The qualitative and quantitative determination of naphthol isomers is therefore of great significance. Herein, β‐cyclodextrin (β‐CD)‐platinum nanoparticles (Pt NPs)/graphene nanosheets (GNs) nanohybrids (β‐CD‐PtNPs/GNs) were prepared for the first time using a simple wet chemical method and characterized by atomic force microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and electrochemical methods, and then applied successfully in the ultrasensitive electrochemical detection of naphthol isomers. The results show that the oxidation peak currents of naphthol isomers obtained at the glassy carbon (GC) electrode modified with β‐CD‐PtNPs/GNs are much higher than those at the β‐CD/GNs/GC, PtNPs/GNs/GC, GNs/GC, and bare GC electrodes. Additionally, compared with other electrochemical sensors developed previously, the proposed electrode results in improved detection limits of about one order of magnitude for α‐NAP (0.23 nM ) and three orders of magnitude for β ‐NAP (0.37 nM ).     

Nd2Fe14B/PANI磁粉的合成、表征及氧传递作用

经球磨和原位聚合法合成了Nd₂Fe₁₄B/PANI磁粉,采用X射线衍射（XRD）、傅里叶变换红外（FTIR）光谱、扫描电镜（SEM）、振动样品磁强计（VSM）对样品进行了表征,用电化学三电极体系和锌空电池考察了Nd₂Fe₁₄B/PANI材料在氧传递中的作用.结果表明:Nd₂Fe₁₄B/PANI是一维片状纳米材料,电导率0.54 S·cm^-1,内禀矫顽力和剩余磁化强度为149.57 kA·m^-1、20.27A·m²·kg^-1;Nd₂Fe₁₄B/PANI负载密度为0.40 mg·cm^-2时,磁性电极的双电层电容增大,传荷电阻减小,磁性锌空电池的极化电流较大;负载密度为3.60 mg·cm^-2时,磁性电极的双电层电容减小,传荷电阻增大,磁性锌空电池的极化电流较小.Nd₂Fe₁₄B/PANI负载密度小于0.89 mg·cm^-2时,微磁场促进氧的传质,提高锌空电池的放电性能;高于3.56 mg·cm^-2时,微磁场抑制氧的传质,降低锌空电池的放电性能;Nd₂Fe₁₄B/PANI中的PANI提高锌空电池的放电性能.     

Chemical polymerization of aniline on a poly(styrene sulfonic acid) membrane: Controlling the polymerization site using different oxidants

Poly(styrene sulfonic acid) membranes (Neosepta CMX, Tokuyama Corp.) have been modified by in situ polymerization of aniline. (NH4)2S2O8, FeCl3, H2O2, and KIO3 were used as oxidizing agents, and two different modification methods (single-step versus two-step) were studied. The composite membranes were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, elemental analysis, electrodialysis, ion-exchange capacity, and conductivity measurements. Our results demonstrate that it is possible to control the polymerization site of aniline which in turn affects the membrane selectivity properties. Hence, composite membranes having a very thin and homogeneous surface polyaniline layer lead to a very low transport of Zn 2+ without increasing significantly the resistance to H+ conductivity. On the other hand, membranes containing about the same quantity of PANI but inside the membrane do not block the transport of Zn 2+.     

Synthesis and Electrochemical Investigation of Tetra Amino Cobalt (II) Phthalocyanine Functionalized Polyaniline Nanofiber for the Selective Detection of Dopamine

A new electrochemical sensing platform based on tetra‐amino cobalt (II) phthalocyanine (TACoPc) ingrained polyaniline (PANI) nanofiber composite (TACoPc/PANI hybrid) has been developed for the selective detection of dopamine. The uniform fibrous network of PANI/TACoPc hybrid was synthesized by a one‐step oxidative polymerization at room temperature. The synthesized nanocomposite was characterized using field emission scanning electron microscopy (FESEM), energy dispersive X‐ray (EDX), fourier transmission infrared spectroscopy (FTIR), raman spectroscopy, X‐ray diffraction (XRD) and UV‐Visible spectroscopy. The electrochemical behavior of the TACoPc/PANI hybrid material was studied by using different electrochemical techniques, including cyclic voltammetry (CV) and chronoamperometry in 0.1 M phosphate buffer solution (PBS) of pH 7 by modifying the glassy carbon electrode (GCE). Due to the synergistic impact of PANI and TACoPc, the suggested altered electrode provided superior catalytic performance for dopamine even in the presence of ascorbic acid. It exhibited a linear reaction with a high sensitivity of 1.212 μA/μM cm^?2 and a low detection limit of 0.064 μM over the 20–200 μM concentration range in 0.1 M PBS. One of the commonly faced problems of interference of ascorbic acid and uric acid in the electrochemical detection of dopamine was completely excluded from this modified electrode which led to an increase in the catalytic activity of the material for the detection of dopamine in the presence of ascorbic acid.     

聚苯胺/ZnFe_2O_4纳米复合物的制备与表征

以Fe(NO3)3·9H2O和Zn(NO3)2·6H2O为原料,采用改进的柠檬酸盐前驱物法合成了片状ZnFe2O4,进一步通过原位聚合反应得到了聚苯胺(PANI)/ZnFe2O4纳米复合物。利用X射线粉末衍射、扫描电子显微镜、透射电子显微镜、红外光谱以及荧光光谱等测试技术对其进行了表征。实验结果表明,通过原位聚合反应PANI沉积在片状ZnFe2O4表面。X射线粉末衍射和红外光谱进一步证实了PANI/ZnFe2O4纳米复合物的生成。ZnFe2O4的引入提高了PANI的荧光发光性能和热稳定性。     

Amperometric determination of xanthine in fish meat by zinc oxide nanoparticle/chitosan/multiwalled carbon nanotube/polyaniline composite film bound xanthine oxidase

Xanthine oxidase (XOD) was immobilized on a composite film of zinc oxide nanoparticle/chitosan/carboxylated multiwalled carbon nanotube/polyaniline (ZnO-NP/CHIT/c-MWCNT/PANI) electrodeposited over the surface of a platinum (Pt) electrode. A xanthine biosensor was fabricated using XOD/ZnO-NP/CHIT/c-MWCNT/PANI/Pt as working electrode, Ag/AgCl as reference electrode and Pt wire as auxiliary electrode connected through a potentiostat. The ZnO-NPs were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), and the enzyme electrode was characterized by cyclic voltammetry, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and electrochemical impedance spectroscopy (EIS). The biosensor showed optimum response within 4 s at 0.5 V potential, pH 7.0, 35 °C and linear range 0.1-100 μM with a detection limit of 0.1 μM. The enzyme electrode was employed for determination of xanthine in fish meat during storage. The electrode lost 30% of its initial activity after 80 uses over one month, when stored at 4 °C.     

Ternary Ag/Polyaniline/Au nanocomposites: Preparation,characterization and electrochemical properties

Ternary Ag/Polyaniline/Au nanocomposites were synthesized successfully by immobilizing of Au nanoparticles (NPs) on the surface of Ag/Polyaniline (PANI) nanocomposites. Ag/PANI nanocomposites were prepared via in situ chemical polymerization of aniline in the presence of 4-aminothiophenol (4-ATP) capped silver colloidal NPs. Then, uniform gold (Au) NPs were assembled on the surface of resulted Ag/PANI nanocomposites through electrostatic interaction to get Ag/Polyaniline/Au nanocomposites. The nanocomposites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), ultraviolet visible spectroscopy (UV-Vis), thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR). Moreover, Ag/PANI/Au nanocomposites were immobilized on the surface of a glassy carbon electrode and showed enhanced electrocatalytic activity for the reduction of H₂O₂ compared with Ag/PANI.     

Nonenzymatic amperometric sensor of hydrogen peroxide and glucose based on Pt nanoparticles/ordered mesoporous carbon nanocomposite

A simple and facile synthetic method to incorporate Pt nanoparticles inside the mesopores of ordered mesoporous carbons (OMCs) is reported. The Pt/OMCs nanocomposite was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and nitrogen adsorption-desorption. The results show that the incorporation of Pt nanoparticles inside the pores of OMCs does not change the highly ordered two-dimensional hexagonal mesostructure of OMCs matrix. Nonenzymatic amperometric sensor of hydrogen peroxide and glucose based on the Pt/OMCs nanocomposite-modified glassy carbon (GC) electrode is developed. Compared with the original OMCs-modified electrode, the Pt/OMCs-modified electrode displays improved current response towards hydrogen peroxide and gives linear range from 2 to 4212 μM. At an applied potential of −0.08 V, the Pt/OMCs nanocomposite gives linearity in the range of 0.5-4.5 mM glucose in neutral buffered saline solution. This glucose sensor also exhibits good ability of anti-interference to electroactive molecules. The combination the unique properties of Pt nanoparticles and the ordered mesostructure of OMCs matrix guarantees the enhanced response for hydrogen peroxide and glucose.     

In-Situ Electrodeposition of Rhodium nanoparticles Anchored on Reduced Graphene Oxide nanosheets as an Efficient Oxygen Reduction Electrocatalyst

A simple, versatile, and cost-effective one-pot electrochemical deposition is used to fabricate rhodium (Rh) nanoparticles decorated surface of reduced graphene oxide (rGO) functionalized glassy carbon electrode (GCE) for oxygen reduction reaction (ORR) in alkaline media. The chemical and physical structure of the sample is probed via transmission electron microscopy, rotating disk electrode (RDE), X-ray photoelectron spectroscopy, linear sweep voltammetry, and Raman spectroscopy. The synergistic effects between the unique properties of Rh nanoparticles and rGO creates such innovative hybrid that exhibits a catalytic activity comparable to that of the commercial platinum electrocatalyst (Pt/C). As a result, the as-electrodeposited Rh@rGO hybrid exhibits outstanding ORR activity in alkaline media, as evidenced by a larger diffusion-limited current, greater positive onset potential, much better stability and methanol tolerance than Pt/C under the same conditions.     

Graphene–Pt nanocomposite for nonenzymatic detection of hydrogen peroxide with enhanced sensitivity

A sensitive hydrogen peroxide (H₂O₂) sensor was fabricated based on graphene–Pt (GN–Pt) nanocomposite. The GN–Pt was synthesized by photochemical reduction of K₂PtCl₄ on GNs, and characterized by atomic force microscope (AFM), transmission electron microscope (TEM), and energy-dispersive X-ray spectroscopy (EDS). Electrochemical investigations indicated that the GN–Pt exhibited a high peak current and low overpotential towards the reduction of H₂O₂. The GN–Pt modified glass carbon electrode displayed a wide linear range (2–710 μM), low limit of detection (0.5 μM) and good selectivity for detection of H₂O₂ with a much higher sensitivity than that of Pt nanoparticles or graphene modified electrode.     

Au nanoparticles and polyaniline coated resin beads for simultaneous catalytic oxidation of glucose and colorimetric detection of the product

In this letter, we report the synthesis of Au nanoparticles (NPs) and polyaniline (PANI) on the same cation-exchange resin beads and demonstrate their use in catalyzing the oxidation of glucose to gluconic acid by Au NPs and simultaneously in detecting the formation of the acid by the color change of PANI. The synthesis was carried out by exchanging the cations of the resins with HAuCl4 and anilinuium chloride and then reducing the metal ions by NaBH4 to produce Au NPs followed by polymerization of aniline using H2O2. The green emeraldine salt form of PANI thus obtained was treated with NaOH to be converted to blue emeraldine base before use. The deposition of Au NPs was confirmed by a change in color of the bead, visible spectroscopy, X-ray diffraction, and scanning electron microscopic measurements. On the other hand, the presence of PANI was confirmed by Fourier transform infrared (FTIR) and ultraviolet-visible (UV-vis) spectroscopy. The formation of gluconic acid from glucose was confirmed by FTIR spectroscopy. We could detect the presence of glucose of a minimum 1.0 mM concentration in water, using the present method. Our experimental observations demonstrate the possibility of the incorporation of multifunctional components on the surfaces of resins for carrying out a chemical reaction as well as detection of the product.     

Nonenzymatic sensing of glucose at neutral pH values using a glassy carbon electrode modified with graphene nanosheets and Pt-Pd bimetallic nanocubes

We report on a nonenzymatic method for the determination of glucose using an electrode covered with graphene nanosheets (GNs) modified with Pt-Pd nanocubes (PtPdNCs). The latter were prepared on GNs by using N,N-dimethylformamide as a bifunctional solvent for the reduction of both metallic precursors and graphene oxide, and for confining the growth of PtPdNCs on the surface. The modified electrode displays strong and sensitive current response to the electrooxidation of glucose, notably at pH 7. The sensitivities increase in the order of Pt₁Pd₅NCs< Pt₁Pd₃NCs< Pt₅Pd₁NCs< Pt₃Pd₁NCs< Pt₁Pd₁NCs. At an applied potential of +0.25 V, the electrode responds linearly (R?=?0.9987) to glucose in up to 24.5 mM concentration, with a sensitivity of 1.4 μA cm^?2 M^?1. The sensor is not poisoned by chloride, and not interfered by ascorbic acid, uric acid and p-acetamidophenol under normal physiological conditions. The modified electrode also displays a wide linear range, good stability and fast amperometric response, thereby indicating the potential of the bimetallic materials for nonenzymatic sensing of glucose.