离子液体中吡咯的电化学聚合及性质研究

以1-丁基-3-甲基咪唑六氟磷酸盐离子液体作为溶剂和支持电解质,分别在铂电极和导电玻璃电极上电化学聚合得到了聚吡咯,聚合过程中发现,在离子液体中聚合的循环伏安图,其电流的变化和传统有机溶剂中的不同,通过交流阻抗技术研究了修饰电极的电化学性质,采用在线紫外、拉曼、红外谱对聚吡咯进行了光谱表征,得到了聚吡咯的特征峰,采用扫描电镜研究了聚合物的形貌。最后将修饰电极应用到了对对苯二酚的催化反应当中,显示了一定的催化作用。     

Synthesis of new TCH/Ni‐based nanocomposite supported on SBA‐15 and its catalytic application for preparation of benzimidazole and perimidine derivatives

A stable nickel‐decorated SBA‐15 nanocomposite (Ni/TCH@SBA‐15) was synthesized through surface modification of silica nanoparticles with 3‐chloropropyltriethoxysilane (CPTES) and thiocarbohydrazide (TCH) followed by metal–ligand coordination with Ni (II). The structure of this organometallic nanocomposite was characterized by Fourier transform‐infrared, field emission‐scanning electron microscopy, EDAX, transmission electron microscopy, atomic absorption spectroscopy and N₂ adsorption–desorption (Brunauer–Emmett–Teller) techniques. The catalytic performance of Ni/TCH@SBA‐15 (NNTS‐15) was determined for the synthesis of 2‐aryl‐substituted benzimidazoles and 2,3‐dihydroperimidines. The excellent yields within shorter reaction times, simplicity of catalytic methods, non‐toxicity and clean reactions, mild reaction conditions and easy work‐up procedure are the important merits of these synthetic protocols. Moreover, the Ni (II) bonded to the SBA‐15 surface was stable under the catalytic reaction conditions resulting in its efficient recycling and reuse.     

Application of Al2O3 in the electrosynthesis of polypyrrole with fuzzy morphology—Microtentacle

Polypyrrole (PPy) thin films were electrochemically polymerized onto the electrode surface. In this study alumina was used as the template and PPy film was prepared by electrochemical polymerization using Al/Al₂O₃ as the working electrode. Surface morphology of PPy was investigated by scanning electron microscopy (SEM) and the results revealed that the application of the template resulted in PPy with fantastic surface morphology which was called microtentacle and the length of the tentacle could reach 15 µm. The morphology can evidently increase the roughness, thus the surface area of the electrode substrate, and provide an intimate contact with the surrounding brain tissue compared to the hard, stiff metal surface. Relationship between PPy morphology and electrochemical polymerization parameters, such as polymerization time, was investigated. The study provided a fundamental method to prepare a PPy‐modified electrode with high surface area. Potential application of the study is proposed. Copyright © 2007 John Wiley & Sons, Ltd.     

Synthesis and Characterization of Polyaniline/Mesoporous SBA‐15 Nanocomposite

Mesoporous silica SBA‐15 with conducting polyaniline inside the pore channels was synthesized and nanocomposite formation was confirmed by means of X‐ray diffraction, transmission electron microscopy and via an N₂ adsorption isotherm. The nanocomposite was subsequently used as a dispersed phase in electrorheological (ER) fluids, and the ER effect has been demonstrated for the first time using a rotational rheometer with high voltage generator.     

Composites of poly(L‐lactide‐trimethylene carbonate‐glycolide) and surface modified SBA‐15 as bone repair material

This work aims to develop novel composites from a poly(L ‐lactide‐co‐trimethylene carbonate‐co‐glycolide) (PLTG) terpolymer and mesoporous silica (SBA‐15) nanofillers surface modified by post‐synthetic functionalization. SBA‐15 first reacts with a silane coupling agent, γ‐aminopropyl‐trimethoxysilane to introduce ammonium group. PLLA chains were then grafted on the surface of SBA‐15 through ammonium initiated ring‐opening polymerization of L ‐lactide. Composites were prepared via solution mixing of PLTG terpolymer and surface modified SBA‐15. The structures and properties of pure SBA‐15, γ‐aminopropyl‐trimethoxysilane modified SBA‐15 (H₂N‐SBA‐15), PLLA modified SBA‐15 (PLLA‐NH‐SBA‐15), and PLTG/PLLA‐NH‐SBA‐15 composites were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, X‐ray diffraction, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, transmission electron microscopy, N₂ adsorption‐desorption, differential scanning calorimetry, contact angle measurement, and mechanical testing. The results demonstrated that PLLA chains were successfully grafted onto the surface of SBA‐15 with grafting amounts up to 16 wt.%. The PLTG/PLLA‐NH‐SBA‐15 composites exhibit good mechanical properties. The tensile strength, Young's modulus, and elongation at break of the composite containing 5 wt.% of PLLA‐NH‐SBA‐15 were 39.9 MPa, 1.3 GPa, and 273.6%, respectively, which were all higher than those of neat PLTG or of the composite containing 5 wt.% of pure SBA‐15. Cytocompatibility tests showed that the composites present very low cytotoxicity.     

Influence of Pore Structure on Catalytic Properties of Mesoporous Silica-supported Co-B Amorphous Alloys in Hydrogenation of Cinnamaldehyde to Cinnamyl Alcohol

Co‐B amorphous alloy catalysts supported on three kinds of mesoporous silica (common SiO₂, MCM‐41 and SBA‐15) have been systematically studied focusing on the effect of pore structure on the catalytic properties in liquid‐phase hydrogenation of cinnamaldehyde to cinnamyl alcohol (CMO). Structural characterization of a series of different catalysts was performed by means of N₂ adsorption, X‐ray diffraction, transmission electron microscopy, hydrogen chemisorption, and X‐ray photoelectron spectroscopy. Various characterizations revealed that the pore structure of supports profoundly influenced the particle size, location and dispersion degree of Co‐B amorphous alloys. Co‐B/SBA‐15 was found more active and selective to CMO than either Co‐B/SiO₂ or Co‐B/MCM‐41. The superior catalytic activity could be attributed to the higher active surface area, because most of Co‐B nanoparticles in Co‐B/SBA‐15 were located in the ordered pore channels of SBA‐15 rather than on the external surface as found in Co‐B/SiO₂ and Co‐B/MCM‐41. Meanwhile, the geometrical confinement effect of the ordered mesoporous structure of SBA‐15 was considered to be responsible for the enhanced selectivity to CMO on Co‐B/SBA‐15, inhibiting the further hydrogenation of CMO to hydrocinnamyl alcohol.     

Polypyrrole/hexagonally ordered silica nanocomposite as a novel fiber coating for solid-phase microextraction

A highly porous fiber coated polypyrrole/hexagonally ordered silica (PPy/SBA15) materials were prepared for solid-phase microextraction (SPME). The PPy/SBA15 nanocomposite was synthesized by an in situ polymerization technique. The resulting material was characterized by the scanning electron microscopy, thermogravimetric analysis and differential thermal analysis. The prepared nanomaterial was immobilized onto a stainless steel wire for fabrication of the SPME fiber. The fiber was evaluated for the extraction of some polycyclic aromatic hydrocarbons (PAHs) from aqueous sample solutions in combination with gas chromatography-mass spectrometry (GC-MS). A one at-the-time optimization strategy was applied for optimizing the important extraction parameters such as extraction temperature, extraction time, ionic strength, stirring rate, desorption time and desorption temperature. In optimum conditions (extraction temperature 70°C, extraction time 20 min, ionic strength 20% (WV(-1)), stirring rate 500 rpm, desorption temperature 270°C, desorption time 5 min) the repeatability for one fiber (n=3), expressed as relative standard deviation (R.S.D. %), was between 5.0% and 9.3% for the tested compounds. The quantitation limit for the studied compounds were between 13.3 and 66.6 pg mL(-1). The life span and stability of the PPy/SBA15 fiber are good, and it can be used more than 50 times at 260°C without any significant change in sorption properties. The developed method offers the advantage of being simple to use, with shorter analysis times, lower cost of equipment, thermal stability of fiber and high relative recovery in comparison to conventional methods of analysis.     

Poypyrrole/molybdenum trioxide/graphene nanoribbon ternary nanocomposite with enhanced capacitive performance as an electrode for supercapacitor

A polypyrrole/molybdenum trioxide/graphene nanoribbon (PPy/MoO₃/GNR) ternary nanocomposite was successfully synthesized via an in situ method. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses show that MoO₃ was successfully combined with the GNRs. The one-dimensional morphology was observed using field emission scanning electron microscopy and transmission electron microscopy. The electrochemical tests show that the PPy/MoO₃/GNR ternary nanocomposite exhibits the highest specific capacitance (844 F g^?1) among the investigated materials and exhibits good cycling stability for 1000 cycles. These results collectively demonstrate that the combination of each component can efficiently increase the specific capacitance and cycling stability. As such, the method reported herein represents a promising approach for fabricating supercapacitor electrode materials.     

Bismuth‐Containing SBA‐15 Mesoporous Silica Catalysts for Solvent‐Free Liquid‐Phase Oxidation of Cyclohexane by Molecular Oxygen

Bismuth (Bi)‐containing SBA‐15 mesoporous silica catalysts, Bi/SBA‐15, with different Bi loadings were synthesized by a direct hydrothermal method. The materials were characterized in detail by various techniques. Powder‐X‐ray‐diffraction (PXRD), N₂‐adsorption/desorption, and transmission‐electron‐microscopic (TEM) analyses revealed that the well‐ordered hexagonal structure of SBA‐15 is maintained after Bi incorporation. Diffuse‐reflectance UV/VIS, Raman, and X‐ray photoelectron spectroscopy (XPS) showed that the incorporated Bi‐atoms are highly dispersed, most of them entering the internal surface of SBA‐15. The new, very stable catalysts were found to be highly efficient for the oxidation of cyclohexane in a solvent‐free system, molecular oxygen (O₂) being used as oxidant.     

Electrochemistry of Nitrogen‐Doped Carbon Nanotubes (CNx) with Different Nitrogen Content and Its Application in Simultaneous Determination of Dihydroxybenzene Isomers

The bamboo‐shaped nitrogen‐doped carbon nanotubes (CN_x) with different nitrogen content were synthesized using Fe‐containing SBA‐15 molecular sieve as catalyst with thermal decomposition. The CN_x nanotubes prepared were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X‐ray diffraction (XRD) and Raman spectroscopy. The results suggest that there are a larger amount of defective sites on CN_x nanotubes surfaces due to the nitrogen doping and CN_x nanotube with higher nitrogen content possesses lower graphitic ordering in the framework. Furthermore the effects of nitrogen content on the electrochemistry of CN_x modified electrodes were investigated by cyclic voltammetry (CV). CN_x modified electrodes exhibit better electrocatalytic activities to the oxidation of hydroquinone. Moreover CN_x with lower nitrogen content is in favor of the electron transfer between dihydroxybenzene and electrode surface, while CN_x with higher nitrogen content possesses high surface adsorptive ability. CN_x modified electrodes can be applied to determine dihydroxybenzene isomers directly and simultaneously by linear sweep voltammetry technique without previous separation.     

Direct Electrochemistry and Electrocatalysis of Myoglobin Immobilized on Graphene‐CTAB‐Ionic Liquid Nanocomposite Film

This paper describes the direct electrochemistry and electrocatalysis of myoglobin immobilized on graphene‐cetylramethylammonium bromide (CTAB)‐ionic liquid nanocomposite film on a glassy carbon electrode. The nanocomposite was characterized by transmission electron microscopy, scanning electron microscopy, X‐ray photoelectron spectroscopy, and electrochemistry. It was found that the high surface area of graphene was helpful for immobilizing more proteins and the nanocomposite film could provide a favorable microenvironment for MB to retain its native structure and activity and to achieve reversible direct electron transfer reaction at an electrode. The ionic liquid may play dual roles here: it keeps the protein's activity and improves stability of the nanocomposite film; it also serves as a binder between protein and electrode, therefore, enhancing the electron transfer between the protein and the electrode. The nanocomposite films also exhibit good stability and catalytic activities for the electrocatalytic reduction of H₂O₂.     

Electrochemically Prepared Three‐dimensional Porous Nitrogen‐doped Graphene Modified Electrode for Non‐enzymatic Detection of Hydrogen Peroxide

A facile and green electrochemical method for the fabrication of three‐dimensional porous nitrogen‐doped graphene (3DNG) modified electrode was reported. This method embraces two consecutive steps: First, 3D graphene/polypyrrole (ERGO/PPy) composite was prepared by electrochemical co‐deposition of graphene and polypyrrole on a gold foil. Subsequently, the ERGO/PPy composite modified gold electrode was annealed at high temperature. Thus 3DNG modified electrode was obtained. Scanning electron microscopy (SEM), X‐ray photoelectron spectroscopy (XPS) and Raman spectroscopy were used to characterize the structure and morphology of the electrode. The electrode exhibits excellent electroanalytical performance for the reduction of hydrogen peroxide (H₂O₂). By linear sweep voltammetric measurement, the cathodic peak current was linearly proportional to H₂O₂ concentration in the range from 0.6 μM to 2.1 mM with a sensitivity of 1.0 μA μM⁻¹ cm⁻². The detection limit was ascertained to be 0.3 μM. The anti‐interference ability, reproducibility and stability of the electrode were carried out and the electrode was applied to the detection of H₂O₂ in serum sample with recoveries from 98.4 % to 103.2 %.     

Detection of Thiols by o‐Quinone Nanocomposite Modified Electrodes

A chemically modified glassy carbon (GC) electrode was developed as an amperometric sensor for detection of biological thiols. The electrode was modified by inclusion of co‐enzyme pyrroloquinoline quinone (PQQ) and a co‐catalyst of oxidized single wall carbon nanotubes (Ox‐SWNT) into a gold polypyrrole (Au‐PPy) nanocomposite matrix. The electrode (PQQ/Ox‐SWNT/Au‐PPy/GC) was characterized using scanning electron microscopy and cyclic voltammetry. Optimal conditions for the PQQ/Ox‐SWNT/Au‐PPy/GC electrode were determined and then utilized for the amperometric detection of L‐cysteine, N‐acetyl‐L‐cysteine, L‐penicillamine and D, L‐glutathione. The electrochemical response for each thiol in pH 3.2 citrate phosphate buffer at +450 mV (vs. Ag/AgCl) was found to be linear with limit of detections (LOD, S/N=3) ranging from 0.50 µM for L‐penicillamine to 1.55 µM for D, L‐glutathione with sensitivities of 30.2 nA/µM and 3.6 nA/µM respectively. The electrode design is simple and easy to construct using a minimum amount of co‐enzyme and co‐catalyst, resulting in detection methods with very good stability and improved sensitivity for thiol detection.     

Adsorption of aqueous Hg (II) by a novel poly(aniline‐co‐o‐aminophenol)/mesoporous silica SBA‐15 composite

A novel poly(aniline‐co‐o‐aminophenol) (PAOA)/mesoporous silica SBA‐15 nanocomposite was synthesized and investigated for adsorption of Hg (II) from aqueous solutions of wide pH range. A chemical oxidation method was employed for polymerization of aniline and o‐aminophenol on an ordered SBA‐15 template to obtain a significantly enlarged BET surface area of the adsorbent. Efficiency study revealed that the PAOA/SBA‐15 could reach a maximum Hg (II) adsorption capacity of over 400 mg/g. Kinetic study showed that the Hg (II) adsorption by the PAOA/SBA‐15 fitted a pseudo‐second‐order kinetic model, indicating that the mercury adsorption process was predominantly controlled by chemical process. The results of this study also proved that the adsorbed Hg (II) could be effectively desorbed from the PAOA/SBA‐15 in 0.1M HCl and 5% sulfocarbonide solutions. Associated adsorption mechanism was also investigated by means of Fourier transform infrared (FTIR) and X‐ray photoelectron spectroscopy (XPS) techniques. Copyright © 2010 John Wiley & Sons, Ltd.     

用磷钨杂多酸-聚吡咯-氧化铝薄膜修饰玻碳电极测定废水中的对苯二酚

利用草酸电解液一步阳极氧化法在高纯铝表面制得纳米孔阳极氧化铝(AAO)薄膜;随后通过纳米孔阳极氧化铝模板电聚合,将磷钨杂多酸(PW12)掺杂吡咯(Py)溶液修饰到玻碳电极(GCE)表面,制得高灵敏的纳米微粒修饰电极(PW12-PPy/AGCE);研究了PW12-PPy/AGCE的伏安行为,考察了其影响因素;并将该电极应用于废水中对苯二酚的测定.结果表明,所制备的PW12-PPy/AGCE可以用于测定废水中的对苯二酚.     

Organic–inorganic polypyrrole‐surface modified SiO2 hybrid nanocomposites: a facile and green synthetic approach

Organic–inorganic hybrid nanocomposites composed of conductive polypyrrole (PPy) and surface modified silica (SiO₂) were successfully prepared through an in situ chemical oxidative polymerization in supercritical carbon dioxide (scCO₂). SiO₂ nanoparticles were surface modified using 3‐methacryloxypropyltrimethoxysilane (MPTMS) in order to disperse well in the medium. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) showed that the SiO₂ nanoparticles were encapsulated into the polymer. UV‐visible spectra of the diluted colloidal dispersions of PPy/SiO₂ hybrid nanocomposites were similar to those of PPy system. Fourier transform infrared spectroscopy (FT‐IR) suggested the strong interaction between PPy and SiO₂. Surface characterizations of nanocomposites were described by X‐ray photoelectron spectroscopy (XPS). The nanocomposites synthesized in scCO₂ have been shown to possess higher electrical conductivity and thermal stability. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis,characterization, and properties of monodispersed magnetite coated multi‐walled carbon nanotube/polypyrrole nanocomposites synthesized by in‐situ chemical oxidative polymerization

This study describes the preparation of a nanocomposites fabricated from monodispersed 4‐nm iron oxide (Fe₃O₄) coated on the surface of carboxylic acid containing multi‐walled carbon nanotube (c‐MWCNT) and polypyrrole (PPy) by in situ chemical oxidative polymerization. High‐resolution transmission electron microscopy images and X‐ray diffraction (XRD) data indicate that the resulting Fe₃O₄ nanoparticles synthesized using the thermal decomposition are close to spherical dots with a particle size about 4 ± 0.2 nm. The resulting nanoparticles were further mixed with c‐MWCNT in an aqueous solution containing with anionic surfactant sodium bis(2‐ethylhexyl) sulfosuccinate to form one‐dimensional Fe₃O₄ coated c‐MWCNT template for further preparation of nanocomposite. Structural and morphological analysis using field‐emission scanning electron microscopy, high‐resolution transmission electron microscopy, and XRD showed that the fabricated Fe₃O₄ coated c‐MWCNT/PPy nanocomposites are one‐dimensional core (Fe₃O₄ coated c‐MWCNT)‐shell (PPy) structures. The conductivities of these Fe₃O₄ coated c‐MWCNT/PPy nanocomposites are about four times higher than those of pure PPy matrix. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 727–733, 2008     

A MgO Nanoparticles Composite Matrix‐Based Electrochemical Biosensor for Hydrogen Peroxide with High Sensitivity

A novel horseradish peroxidase (HRP) electrochemical biosensor based on a MgO nanoparticles (nano‐MgO)‐chitosan (chit) composite matrix was developed. The morphology of nano‐MgO‐chit nanocomposite was examined by scanning electron microscopy (SEM). The interaction between nano‐MgO‐chit nanocomposite matrix and enzyme was characterized with UV‐vis spectra. This proposed composite material combined the advantages of inorganic nanoparticles and organic polymer chit. The HRP immobilized in the nanocomposite matrix displayed excellent electrocatalytic activity to the reduction of H₂O₂ in the presence of hydroquinone as a mediator. The effects of the experimental variables such as solution pH and the working potential were investigated using steady‐state amperometry. The present biosensor (HRP‐modified electrode) had a fast response towards H₂O₂ (less than 10 s), and excellent linear relationships were obtained in the concentration range of 0.1–1300 μM, with a detection limit of 0.05 μM (S/N=3). Moreover, the stability and reproducibility of this biosensor were evaluated with satisfactory results.     

Fabrication of Au‐Nanoparticle/TiO2‐Nanotubes Electrodes Using Electrochemical Methods and Their Application for Electrocatalytic Oxidation of Hydroquinone

Gold nanoparticle (Au‐NPs)‐Titanium oxide nanotube (TiO₂‐NTs) electrodes are prepared by using galvanic deposition of gold nanoparticles on TiO₂‐NTs electrodes as support. Scanning electron microscopy and energy‐dispersive X‐ray spectroscopy results indicate that nanotubular TiO₂ layers consist of individual tubes of about 60–90 nm diameters and gold nanoparticles are well‐dispersed on the surface of TiO₂‐NTs support. The electrooxidation of hydroquinone of Au‐NPs/TiO₂‐NTs electrodes is investigated by different electrochemical methods. Au‐NPs/TiO₂‐NTs electrode can be used repeatedly and exhibits stable electrocatalytic activity for the hydroquinone oxidation. Also, determination of hydroquinone in skin cream using this electrode was evaluated. Results were found to be satisfactory and no matrix effects are observed during the determination of hydroquinone content of the “skin cream” samples.     

N‐heterocyclic carbene–palladium(II) complex supported on magnetic mesoporous silica for Heck cross‐coupling reaction

Magnetic mesoporous silica was prepared via embedding magnetite nanoparticles between channels of mesoporous silica (SBA‐15). The prepared composite (Fe₃O₄@SiO₂‐SBA) was then reacted with 3‐chloropropyltriethoxysilane, sodium imidazolide and 2‐bromopyridine to give 3‐(pyridin‐2‐yl)‐1H‐imidazol‐3‐iumpropyl‐functionalized Fe₃O₄@SiO₂‐SBA as a supported pincer ligand for Pd(II). The functionalized magnetic mesoporous silica was further reacted with [PdCl₂(SMe₂)₂] to produce a supported N‐heterocyclic carbene–Pd(II) complex. The obtained catalyst was characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, energy‐dispersive X‐ray analysis, vibrating sample magnetometry, Brunauer–Emmett–Teller surface area measurement and X‐ray diffraction. The amount of the loaded complex was 80.3 mg g^?1, as calculated through thermogravimetric analysis. The formation of the ordered mesoporous structure of SBA‐15 was confirmed using low‐angle X‐ray diffraction and transmission electron microscopy. Also, X‐ray photoelectron spectroscopy confirmed the presence of the Pd(II) complex on the magnetic support. The prepared magnetic catalyst was then effectively used in the coupling reaction of olefins with aryl halides, i.e. the Heck reaction, in the presence of a base. The reaction parameters, such as solvent, base, temperature, amount of catalyst and reactant ratio, were optimized by choosing the coupling reaction of 1‐bromonaphthalene and styrene as a model Heck reaction. N‐Methylpyrrolidone as solvent, 0.25 mol% catalyst, K₂CO₃ as base, reaction temperature of 120°C and ultrasonication of the catalyst for 10 min before use provided the best conditions for the Heck cross‐coupling reaction. The best results were observed for aryl bromides and iodides while aryl chlorides were found to be less reactive. The catalyst exhibited noticeable stability and reusability.