模板法制备聚苯胺空心微球材料及其电化学性能

运用模板法,以聚苯乙烯(PS)胶体粒子为微球核,使苯胺单体吸附于PS胶体粒子表面,然后利用原位的化学氧化聚合,制备出聚苯乙烯/聚苯胺(PS/PANI)核壳材料.然后再将PS微球核溶解,最终得到PANl空心微球材料.采用傅立叶变换红外光谱、扫描电子显微镜对所得材料进行成分和形貌的分析.利用循环伏安法、恒流充放电测试法和循...     

接枝聚合聚苯胺/CeO2-COOH复合材料的性能及聚合机制

对二氧化铈(CeO2)进行羧基化改性得到羧基化二氧化铈(CeO2-COOH),并与苯胺(An)接枝聚合得到核壳结构聚苯胺/二氧化铈复合材料(PANI/CeO2-COOH)。采用红外光谱、X射线光电子能谱、X射线衍射、热重分析、扫描电子显微镜及旋转圆盘电化学测试技术分析材料的结构及性能。结果表明,CeO2-COOH的CeIII/CeIV的比值接近1,具有较高的表面氧空位;PANI/CeO2-COOH中PANI接枝效果较好,而且与纯PANI结构相同;CeO2-COOH与PANI之间通过价键接枝形成的PANI/CeO2-COOH复合材料起始分解温度在228℃左右,且在200~600℃内的分解速率较慢,表现出较好的热稳定性;在1mol/LH2SO4中对电极进行循环伏安和恒电流充放电测试,PANI/CeO2-COOH复合材料电极不仅具有良好的峰对称性和最高阳极峰电流,而且还具有较好的电容性能,当电流密度为0.5A/g时,比电容达到149.5F/g。     

Preparation, characterization and photocatalytic activity of TiO2/polyaniline core-shell nanocomposite

Polyaniline (PANI) as a promising conducting polymer has been used to prepare polyaniline/TiO₂ (PANI/TiO₂) nanocomposite with core-shell structure as photocatalyst. Titanium dioxide (TiO₂) nanoparticles with an average crystal size of 21?nm were encapsulated by PANI via the in situ polymerization of aniline on the surface of TiO₂ nanoparticles. FT?CIR, UV-Vis-NIR, XRD, SEM and TEM techniques were used to characterize the PANI/TiO₂ core-shell nanocomposite. Photocatalytic activity of PANI/TiO₂ nanocomposite was investigated under both UV and visible light irradiations and compared with unmodified TiO₂ nanoparticles. Results indicated deposition of PANI on the surface of TiO₂ nanoparticles which improved the photocatalytic activity of pristine TiO₂ nanoparticles.     

Gold/palladium and silver/palladium colloids as novel metallic substrates for surface-enhanced Raman scattering

New surface-enhanced Raman scattering (SERS) substrates, composed of gold or silver colloidal nanoparticles doped with palladium, were prepared. These novel colloids are stable and maintain a satisfactory SERS efficiency, even after long aging. The interest in doping the coinage metal nanoparticles with palladium is due to the well-known catalytic activity of this metal. Transmission electron microscopy (TEM) and ultraviolet-visible absorption spectroscopy were used to characterize the shape and size of the metal particles. It was found that these bimetallic colloidal nanoparticles have a core-shell structure, with gold or silver coated with palladium clusters.     

Gold/boron core-shell nanocables synthesized from gold-boron eutectic droplets

Metal/semiconductor core-shell coaxial nanocables are promising building blocks for nanoelectronic devices while in situ growth of these nanocables remains challenging due to the distinctly different synthesis temperature ranges required for metals and semiconductors. To overcome this difficulty, we have developed a vapor-liquid-solid and oxide-assisted bimodal competition growth strategy for in situ metal/semiconductor core-shell nanocable growth. Using this process, gold/boron core-shell nanocables were obtained. A core-shell Au-B/BO(x) eutectic droplet formed via hydrogen gas-assisted rapid cooling was found critical for initiation of the nanocable growth. In addition, the large difference in the boron nanowire growth rates in the vapor-liquid-solid and oxide-assisted mechanisms facilitates the layered growth in the nanocables. The compatibility of this method with the vapor-liquid-solid process applied widely for semiconductor nanowire growth allows in situ connection of metal/semiconductor nanocables with semiconductor nanowires.     

Hybrid Au-CdSe and Ag-CdSe nanoflowers and core-shell nanocrystals via one-pot heterogeneous nucleation and growth

A general approach, based on heterogeneous nucleation and growth of CdSe nanostructures on Au or Ag nanocrystals, for the synthesis of Au-CdSe and Ag-CdSe hybrid nanostructures is developed. The new approach provides a versatile one-pot route for the synthesis of hybrid nanoflowers consisting of a gold or silver core and multipod CdSe rods or an intact CdSe shell with controlled thickness, depending on the nucleation and growth parameters. At lower growth temperatures such as 150 °C, the CdSe clusters are adsorbed on the surface of the metal cores in their surface defects, then multiple arms and branches form, resulting in nanoflower-shaped hybrid structures. Increasing the size of the metal core through the choice of the reducing and capping agents results in an improvement of the interface between the metal and CdSe domains, producing core-shell structures. The growth temperature appears to be the most important factor determining the nature of the interface between the metal and CdSe domains. At relatively high temperatures such as 300 °C, the formation of large, faceted Au cores creates preferential growth sites for the CdSe nanocrystalline shell, thus resulting in well-defined Au-CdSe core-shell structures with large interfaces between the Au and CdSe domains. The present approach is expected to foster systematic studies of the electronic structures and optical properties of the metal-semiconductor hybrid materials for potential applications in photovoltaic and nanoelectronic devices.     

Preparation of controllable core-shell gold nanoparticles and its application in detection of silver ions

We report a novel shell technique to prepare controllable core-shell nanoparticles. In this technique, the shell is formed when the core reacts with metal ions and Na(2)S(2)O(3) and the size of the core and thickness of the shell can be controlled. Transmission electron microscopy and X-ray diffraction reveal that the shell consists of insoluble complex salts comprising Au(2)S, AuAgS, and Ag(3)AuS(2). The resulting core-shell nanoparticles obtained at different reaction stages demonstrate that the formation of Au(2)S, AuAgS, and Ag(3)AuS(2) shell proceeds from the outside. The morphological evolution of the particles changes significantly with reaction time demonstrating that formation of the shell results from diffusion in the solid shell. The core-shell nanoparticles produced by this technique can be used as nanosensors to detect Ag(+) in aqueous media with high selectivity and sensitivity. The excellent selectivity for Ag(+) is demonstrated by comparing the response to other metal ions. In addition, our evaluation indicates that gold nanorods offer higher sensitivity than gold nanospheres.     

Study on the infrared property of polyaniline/multi-wall carbon nanotube composite

Composites of polyaniline (PANI) and multi-wall carbon nanotube (MWNT) were synthesized by in situ polymerization with different MWNT content. The composites were characterized by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The SEM photos indicated that a mass of MWNT was enchased into PANI matrix when the content of MWNT was low. With the MWNT content increases, the surface of MWNT was covered with PANI and formed the core-shell structure. From the FT-IR spectroscopy of the composites, it can be confirmed that there was interaction between PANI and multi-wall carbon nanotube. The composites had better thermal stability than pure PANI. Infrared emission property of the composites was analyzed by an IR-II infrared emissivity instrument and an infrared camera. It was found that infrared emission of the composites was lower than pure PANI in all wavelength range and infrared emissivity value was related to the content of MWNT in the composites.     

Ti02光催化核壳材料的研究进展

TiO<,2>核壳材料作为光催化剂具有活性高、稳定性强、普适性广、应用前景广阔等优点而引起了人们广泛的兴趣.综述了近年来TiO<,2>核壳材料用作光催化剂的最新研究成果,主要包括TiO<,2>与金属、半导体、磁性材料等复合所得核壳材料及TiO<,2>自身组成核壳材料在光催化领域的应用,指出TiO<,2>与金属、半导体复合或离子掺杂等所得核壳材料都不同程度地提高了其催化性能;与磁性材料复合时虽然易于分离但是活性不理想;当以TiO<,2>为核时,通过控制合成条件可以制备出孔径不同的TiO<,2>壳层,该类核壳材料可以选择性地降解有机物.最后指出深入探讨TiO<,2>核壳材料光催化机理、开发易回收高效TiO<,2>催化剂及寻找简易制备TiO<,2>核壳材料的方法是未来TiO<,2>核壳材料研究的重要方向.     

Fabrication and characterization of poly(N-isopropyl acrylamide)-gold nanoshell structures

Novel core-shell structures were presented here which consist of Poly(N-isopropyl acrylamide) (PNIPAM) microspheres as cores and gold as shells. The fabrication of these structures was convenient because the modifications to PNIPAM or gold nanoparticles (GNPs) were omitted. GNPs were attached to the surface of PNIPAM microspheres by means of electrostatic adsorption, and then acted as seeds to grow quickly into complete shells by optimizing the pH of the HAuCl4 solution to control the growth rate of gold nanoshells (GNSs). These structures combine the thermo-responsive behavior of PNIPAM microspheres with optical property of GNSs, and the localized surface plasmon resonance (LSPR) of the GNSs can be changed by adjusting the temperature of the PNIPAM microspheres which make them have great prospects for drug release. Their good biological stability in bovine serum albumin (BSA) and the LSPR located near 700 nm are expected for optical biosensors and optical analysis of whole-blood.     

Fe(3)O(4)@Au/polyaniline multifunctional nanocomposites: their preparation and optical, electrical and magnetic properties

Fe(3)O(4)@Au/polyaniline (PANI) nanocomposites were fabricated by in situ polymerization in the presence of mercaptocarboxylic acid. The mercaptocarboxylic acid was used to introduce hydrogen bonding and/or electrostatic interaction; it acts as a template in the formation of Fe(3)O(4)@Au/PANI nanorods. The morphology and structure of the resulting nanocomposites were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy, x-ray diffraction and x-ray energy dispersion spectroscopy (EDS). It was found that the nanocomposites were rod-like with an average diameter of 153?nm, and they exhibited a core-shell structure. A UV-visible spectrometer, semiconductor parameter analyzer and vibrating sample magnetometer (VSM) were used to characterize the optical, electrical and magnetic properties of the Fe(3)O(4)@Au/PANI nanocomposites. It was interesting to find that these properties are dependent on the molar ratio of Au to Fe(3)O(4) when the molar ratio of Fe(3)O(4)@Au to PANI is fixed. The magnetic property of the Fe(3)O(4)@Au/PANI nanocomposite is very close to superparamagnetic behavior.     

Preparation of Au-loaded niobate nanosheets and their plasmon-driven photochemical reaction

Niobate nanosheets prepared by exfoliation of layered hexaniobate K₄Nb₆O₁₇ were sequentially decorated with two noble metal nanoparticles, gold and silver, through two-step photochemical reactions. First, cationic bis(ethylenediamine)gold(III) ions were electrostatically adsorbed on the anionic niobate nanosheets, and reduced to gold nanoparticles by UV excitation of the photocatalytically active niobate nanosheets. Then, the surface plasmon band of the photodeposited gold nanoparticles was excited with visible light, by which the silver cations introduced to the system together with citrate anions were reduced to silver nanoparticles. Spectroscopic and transmission electron microscopic observations indicated the formation of morphologically different silver nanoparticles, for example nanorods and core-shell particles.     

One-pot synthesis of (Au nanorod)-(metal sulfide) core-shell nanostructures with enhanced gas-sensing property

(Au nanorod)-(metal sulfide) core-shell structures are synthesized by employing Au nanorods as the starting reactants and metal thiobenzoates as the metal sulfide precursors in the presence of Ag(+) ions. The gas-sensing property of the prepared (Au nanorod)-CdS sensor exhibit a significantly enhanced response and higher sensitivity in comparison with a CdS sensor.     

羰基铁粉/聚甲基丙烯酸甲酯/聚苯胺复合吸波剂的制备与性能

以苯胺(ANI)、羰基铁粉(CIP)和甲基丙烯酸甲脂(MMA)等为原料,采用化学氧化法和原位复合技术制备了掺杂态聚苯胺(PANI)、羰基铁粉/聚甲基丙烯酸甲脂(CIP/PMMA)和羰基铁粉/聚甲基丙烯酸甲脂/聚苯胺(CIP/PMMA/PANI)吸波剂,用XRD、SEM、TEM表征了吸波剂的结构与形貌,通过矢量网络分析仪测定吸波剂的电磁参数表明CIP/PMMA/PANI复合吸波剂既有电损耗又有磁损耗。在2～18 GHz频段内,材料厚度为1.0 mm时,计算出其最小反射率达-11.26 dB,反射率小于-10 dB的带宽为9.2 GHz、小于-8 dB的带宽达14 GHz,计算结果表明该复合吸波剂具有良好的宽频吸波性能。      

Bipolar Resistive Switching of Single Gold-in-Ga(2)O(3) Nanowire

We have fabricated single nanowire chips on gold-in-Ga(2)O(3) core-shell nanowires using the electron-beam lithography techniques and realized bipolar resistive switching characteristics having invariable set and reset voltages. We attribute the unique property of invariance to the built-in conduction path of gold core. This invariance allows us to fabricate many resistive switching cells with the same operating voltage by simple depositing repetitive metal electrodes along a single nanowire. Other characteristics of these core-shell resistive switching nanowires include comparable driving electric field with other thin film and nanowire devices and a remarkable on/off ratio more than 3 orders of magnitude at a low driving voltage of 2 V. A smaller but still impressive on/off ratio of 10 can be obtained at an even lower bias of 0.2 V. These characteristics of gold-in-Ga(2)O(3) core-shell nanowires make fabrication of future high-density resistive memory devices possible.     

A thin PANI and carrageenan–gold nanoparticle film on a flexible gold electrode as a conductive and low-cost platform for sensing in a physiological environment

In this work, we report the production of a layer-by-layer (LbL) film of gold nanoparticles stabilized with carrageenan (carr-AuNPs) interspersed with a conductive polyaniline (PANI) layer. Conventionally, PANI has poor electroactivity in physiological buffers, limiting its using in electrochemical biosensors. The films were prepared on low cost and easy to manufacture flexible gold electrodes (FEAu). Two adsorption sequences were tested for production of the films—PANI/carr-AuNP and carr-AuNP/PANI. The gold nanoparticle size and colloidal stability were characterized. The films were characterized by cyclic voltammetry, UV–visible spectroscopy and atomic force microscopy. The results showed the synergistic effects of the carr-AuNPs (120 nm) and PANI, which improved both the electrochemical response and the stability of the conductive polymer in physiological medium by three times. The presence of the carr-AuNPs in the film caused a significant increase in roughness of the FEAu-modified electrode compared to that of an unmodified electrode, resulting in an increased active electrode area. Studies of film growth by UV–Vis spectroscopy indicated that the deposition mechanisms of both films involved an auto-regulating adsorption process, with the same amount of material adsorbed in each coating step. The PANI/carr-AUNP film showed considerable improvement in stability and conductivity compared to PANI-only films in the physiological environment, which confers advantages for use as a biosensor.     

Synthesis of multi-walled carbon nanotube/silica nanoparticle/polystyrene microsphere/polyaniline based hybrids for EMI shielding application

Novel polystyrene microsphere (PSMS)-based PSMS/Si and polystyrene/silica nanoparticle/multi-walled carbon nanotube (PS/Si/MWCNT) nanocomposite has been prepared using in situ sol-gel and chemical amalgamation methods. Aniline monomer was introduced by in situ route to form PSMS/PANI, PSMS/PANI/Si and PSMS/PANI/Si/MWCNT nanocomposite. FESEM of nanocomposite indicated core-shell spherical and tubular morphology. Glass transition temperature (T_g) and maximum decomposition temperature (T_max) of PSMS/PANI/Si/MWCNT nanocomposite were found as 295°C and 524°C, respectively, which were higher than the PSMS/PANI (T_g = 245°C; T_max = 387°C) and PSMS/PANI/Si (T_g = 257°C; T_max = 388°C) nanocomposite. For nanocomposite dispersion, tetrahydrofuran was studied as fine solvent. XRD depicted amorphous nature of PSMS/Si and PSMS/PANI/Si; however MWCNT reduced amorphous character of PSMS/PANI/Si/MWCNT. Electromagnetic interference (EMI) shielding effectiveness improved from 0.1 dB (PSMS) to 12.3 dB (PSMS/PANI/Si) to 24.5 dB (PSMS/PANI/Si/MWCNT). The increase in EMI shielding effectiveness was also observed with variation in log of conductivity from ?14 mho m^?1 (PSMA) to 1.17 mho m^?1 (PSMS/PANI/Si/MWCNT).     

聚苯胺包覆CoFe类普鲁士蓝复合材料的超电容性能

制备了聚苯胺包覆CoFe类普鲁士蓝纳米立方（CoFePBA@PANI）复合材料,采用XRD、FTIR、SEM和TEM对CoFePBA@PANI复合材料的结构和形貌进行表征,利用循环伏安法（CV）、恒电流充放电法及交流阻抗法（EIS）对CoFePBA@PANI复合材料的电化学性能进行了考察。结果表明:通过植酸的配位作用促使苯胺在具有面心立方结构的CoFePBA表面发生聚合反应,形成了具有核-壳结构的CoFePBA@PANI复合材料。系统地研究了PANI的含量对CoFePBA@PANI复合材料电化学性能的影响,CoFePBA@PANI复合材料在0.5 mol/L Na₂SO₄和H₂SO₄的混合酸性介质中,在1 A/g电流密度下,比电容值达到401.2 F/g,电流密度增大至10 A/g时,比电容仍能保持在367.3 F/g。      

Large-scale preparation of polyaniline nanospheres anchored with thiol-stabilized gold nanoparticles

Reported herein is the preparation of a new nanostructured composite consisting of PANI(SH) (where PANI(SH) is poly(aniline-co-4-aminothio phenol)) and gold nanoparticles (AuNPs)) via "seed"-induced bulk polymerization. The PANI(SH)-AuNPs composite was designated as PANI(SH)-Au-NS(P). The composite was characterized in terms of its morphology and structural, thermal, and electrochemical properties. The field emission scanning electron microscopy (FESEM) image of PANI(SH)-Au-NS(P) revealed the presence of PANI(SH) nanospheres (sizes: approximately 150-250 nm) with finely distributed AuNPs (approximately 10 nm). The usefulness of PANI(SH)-Au-NS(P) as an electrocatalyst towards the oxidation of methanol was tested.     

Electrochemical DNA biosensor based on conducting polyaniline nanotube array

Most of the recent developments in ultrasensitive detection of nucleic acid are based on the gold nanoparticles and carbon nanotubes as a medium of signal amplification. Here, we present an ultrasensitive electrochemical nucleic acid biosensor using the conducting polyaniline (PANI) nanotube array as the signal enhancement element. The PANI nanotube array of a highly organized structure was fabricated under a well-controlled nanoscale dimension on the graphite electrode using a thin nanoporous layer as a template, and 21-mer oligonucleotide probes were immobilized on these PANI nanotubes. In comparison with gold nanoparticle- or carbon nanotube-based DNA biosensors, our PANI nanotube array-based DNA biosensor could achieve similar sensitivity without catalytic enhancement, purification, or end-opening processing. The electrochemical results showed that the conducting PANI nanotube array had a signal enhancement capability, allowing the DNA biosensor to readily detect the target oligonucleotide at a concentration as low as 1.0 fM (approximately 300 zmol of target molecules). In addition, this biosensor demonstrated good capability of differentiating the perfect matched target oligonucleotide from one-nucleotide mismatched oligonucleotides even at a concentration of 37.59 fM. This detection specificity indicates that this biosensor could be applied to single-nucleotide polymorphism analysis and single-mutation detection.