Attenuated total reflection Fourier transform infrared spectra of faceted diamonds

In this work, the contributions of cationic and elemental gold on roughened gold substrates to surface-enhanced Raman scattering (SERS) of polypyrrole (PPy) films were first investigated. First, a gold substrate was roughened by a triangular wave oxidation-reduction cycle (ORC) in an aqueous solution containing 0.1 M KCl. Then, the roughened gold substrate was further reduced by applying a cathodic potential for a fixed time to control the quantity of unreduced cationic Au on the roughened Au substrate. The result indicates that the content of cationic Au is responsible for the improved SERS of PPy electrodeposited on this roughened Au substrate. This phenomenon can be attributed to the interfacial charge transfer from PPy to the roughened Au substrate by the aid of cationic Au.     

Characteristics of polypyrrole electrodeposited onto roughened substrates composed of gold–silver bimetallic nanoparticles

In this work, the characteristics of polypyrrole (PPy) films electrodeposited onto an electrochemically roughened gold substrate with bimetallic silver and gold nanoparticles were first investigated. First, a silver substrate was roughened by a triangular‐wave oxidation–reduction cycle (ORC) in an aqueous solution containing 0.1 M HCl. Subsequently, a gold substrate was roughened by a similar ORC treatment in this used solution. The results revealed that the surface of the roughened gold substrate demonstrated two different kinds of deposition domains because of the modification of silver nanoparticles. Encouragingly, some novel characteristics of PPy deposited onto this substrate were observed, in comparison with those on the roughened gold substrate without the modification of silver nanoparticles. They included a denser and more compact surface morphology, higher oxidation degree, increased conductivity, and improved surface‐enhanced Raman scattering. Furthermore, the nucleation and growth mechanism for PPy electropolymerization on this silver‐modified roughened gold substrate was distinguishable from that on the unmodified one. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2724–2731, 2006     

Characteristics of Cl‐ and Au‐Containing Nanocomplex and Its Effect on the Following Electrodeposition of Polypyrrole

In this study, polypyrrole (PPy) films were electrochemically deposited on gold substrates roughened by a triangular‐wave oxidation‐reduction cycle (ORC) with different anodic and cathodic vertexes in an aqueous solution containing 0.1 N NaCl. In ORC treatment, the Cl‐ and Au‐containing nanocomplex was formed on the surface of gold. The results indicate that the crystalline orientation and diameter of Au are significantly different before and after ORC treatment. Also the redox behavior in ORC, surface morphology formed and depth profile of Cl in the nanocomplex are influenced by the anodic and cathodic vertexes used in roughening Au. The roughened Au demonstrates an electrocatalytic activity for pyrrole polymerization. Correspondingly, the characteristics of PPy films electrodeposited on these roughened Au substrates are notable. They include the surface‐enhanced Raman scattering (SERS) effect shown, a higher conductivity obtained and an increase in oxidation level demonstrated.     

Strategy for obtaining improved surface-enhanced Raman scattering by combining electrochemical and plasmas technologies

In this work, surface-enhanced Raman scattering (SERS)-active gold substrates were first developed by combining the technologies of oxidation–reduction cycles (ORCs) and plasmas treatments in roughening metal substrates. First, a gold substrate was treated by argon plasmas. Then the treated gold substrate was further roughened by triangular-wave ORCs in an aqueous solution containing 0.1 M HCl. Encouragingly, the SERS of Rhodamine 6G (R6G) adsorbed on this roughened gold substrate modified by argon plasmas pretreatment exhibits a higher intensity by 10-fold of magnitude and a better resolution, as compared with the SERS of R6G adsorbed on an unmodified roughened gold substrate. Meanwhile, the probing concentration of R6G adsorbed on the modified substrate can be reduced by one order. It was also found that the pretreatment of argon plasmas demonstrates a positive effect on the (2 2 0) face of Au partly changing into the (1 1 1) face with the lowest surface energy after the ORCs roughening, which is contributive to the improved SERS observed.     

Direct evidence of chemical effect of surface-enhanced Raman scattering observed on electrochemically prepared rough gold substrates

In this study, polypyrrole (PPy) films were electrochemically deposited on gold substrates roughened by an electrochemical triangular-wave oxidation-reduction cycles (ORC) in an aqueous solution containing 0.1N KCl. Then the substrates were heated from 25 to 50 °C and the corresponding SERS performances of PPy were observed in situ. The results indicate that the SERS enhancement capabilities of substrates are gradually raised from 25 °C to a maximum at 40 °C and monotonically decreased from 40 to 50 °C. These SERS enhancement capabilities ascribed to the charge transfers from PPy to Au, which are responsible for the chemical effects of SERS mechanisms, are successfully observed via SERS and high resolution X-ray photoelectron spectroscopy (HRXPS) analyses. The variation in content of the oxidized PPy peak of the double peaks in the range of 1000-1150 cm⁻¹ in SERS spectrum obtained on an Au substrate at different temperatures is consistent with its corresponding variation in the SERS intensity of PPy. The variation in content of the oxidized nitrogen of PPy deposited on an Au substrate at different temperatures revealed from an HRXPS analysis also confirms this consistence.     

Temperature effect of electrochemically roughened gold substrates on polymerization electrocatalysis of polypyrrole

In this work, electrochemical methods were used to prepare complexes with Au and Cl species on bulk Au substrates. Then the electrochemically roughened Au substrates were further heat-treated at different temperatures. The effect of temperatures used in heat treatments between 25 and 100 °C on electrocatalytical polymerization of polypyrrole (PPy) formed on the prepared gold substrates was first investigated. The result indicates that the optimally electrocatalytical capability of the heat-treated Au substrate for PPy polymerization is at 75 °C. Moreover, the autopolymerized PPy on the roughened Au substrate treated at 75 °C demonstrates the highest oxidation level and oxidation degree of 0.32 and 0.50, respectively. Primary results indicate that complexes with positively charged Au act as oxidants, and perchlorate and chloride ions act as dopants for the oxidation-polymerization of PPy.     

Electropolymerization of DBSA‐doped polypyrrole films on PTFE via an electroless copper interlayer

We report on the electroless deposition of thin films of copper on poly(tetrafluoroethylene) (PTFE) and their use as substrates for electropolymerization of polypyrrole. Argon plasma‐treated PTFE films were modified by silanization using N‐[3(trimethoxysilyl)propyl]diethylenetriamine (TMS). The TMS‐modified PTFE films were subsequently activated by PdCl₂ for the electroless deposition of copper. The omission of the commonly used SnCl₂ sensitization step represents a significant process enhancement with environmental and cost benefits. The surface composition of the substrate (before and after surface treatments) and overlayer films was studied using high‐resolution x‐ray photoelectron spectroscopy. A combination of time‐of‐flight secondary ion mass spectrometry and water contact‐angle measurements was also used to study the PTFE surface after argon plasma treatment. The Cu/PTFE films were used as substrates for subsequent pyrrole electropolymerization in aqueous dodecylbenzene sulphonic acid (DBSA) solution. The DBSA‐doped polypyrrole overlayers were successfully deposited on the Cu/PTFE surface using a constant applied potential of 1.5 V. The resulting material exhibited a doping level of 39%, determined using chemical component analysis of the N 1s photoelectron peak. Copyright © 2003 John Wiley & Sons, Ltd.     

Polypyrrole on self-assembled monolayers of a pyrrolyl lipoic acid derivative—electrosynthesis and polymer film characterization

The electropolymerization of pyrrole on gold modified by a self-assembled monolayer (SAM) of a pyrrolyl lipoic acid derivative was investigated in detail and the results compared to those obtained on bare substrates. Both under potentiostatic and potentiodynamic control, a slight blocking action of the underlying SAM could be observed for the initial stages of polymer growth but thereafter the electrochemical features were similar to those collected for polypyrrole (PPy) deposition on bare gold. The morphology and structure of PPy films formed on the SAMs were characterized by atomic force microscopy and X-ray diffraction, which revealed that those polymer properties are much more influenced by the electrochemical mode of preparation, than by the underlying SAMs. While, when compared to PPy on bare gold, no effect has been detected on thin layers deposited at constant potential, surface areas with rather irregular morphology, as well as a small but beneficial influence in inducing order on the first few layers of the polymer film, have been observed on similar films formed by cyclic voltammetry. The typical globular morphology of PPy has always been observed for relatively thick layers in which the redox behavior, analyzed by in situ AFM, showed an increase in volume of the polymer nodules upon reduction, largely due to the SAM reorganization induced by the applied potential.     

Trace molecules detectable by surface-enhanced Raman scattering based on newly developed Ag and Au nanoparticles-containing substrates

In this work, Ag and Au nanoparticles-containing substrates were first developed for obtaining a stronger surface-enhanced Raman scattering (SERS) intensity of Rhodamine 6G (R6G) and reducing the limit of detection (LOD) of trace molecules. First, the optimum electrochemically roughening conditions employed on Ag substrates for obtaining strongest SERS of R6G were investigated. Then the optimally roughened Ag substrates were incubated in the prepared Cl- and Au-containing solutions for different couples of minutes to undergo the galvanic replacement reactions. Encouragingly, the SERS of R6G adsorbed on this roughened Ag substrate modified by the replacement of Ag with Au for 5 min exhibits a higher intensity by 8-fold of magnitude, as compared with the SERS of R6G adsorbed on an unmodified roughened Ag substrate. Moreover, the practical LOD of R6G can be reduced by one order of magnitude from 1 ppq to 0.1 ppq. Further investigations indicate that the compositions of complexes formed on the substrates demonstrate decided effects on the improved SERS.     

Effects of electrolytes used in roughening gold substrates by oxidation–reduction cycles on surface-enhanced Raman scattering

In this work, the effects of electrolytes used in roughening gold substrates by electrochemical methods on surface-enhanced Raman scattering (SERS) were first investigated. First, gold substrates were roughened by triangular-wave oxidation–reduction cycles (ORC) in aqueous solutions containing different kinds of 0.1 M electrolytes. Then Rhodamine 6G (R6G) was used as Raman probe to examine this effect of electrolytes used on the SERS observed. The result indicates that the highest intensity of SERS of R6G was obtained on the roughened Au substrate prepared in 0.1 M NaCl, which was less used in the literature. Meanwhile, it was also found that the rougher surface morphology observed, which is contributive to the higher SERS obtained, is corresponding to the smaller cathodic peak area shown in the cyclic voltammograms for roughening the Au substrate.     

金属基底上吡咯光电化学聚合的研究

近年来,国内外对聚吡咯已进行广泛的研究,主要内容包括:电化学聚合,机理与结构表征,电化学氧化还原性质,聚吡咯的化学修饰。最近报导了半导体上吡咯的光电化学聚合。我们在低于吡咯电聚合电位下观察到聚吡咯的Raman讯号。本文研究在中性溶液中金属基底上吡咯的光电化学聚合,以及光源波长、强度和介质等因素的影响。     

Flexible and wearable graphene/polypyrrole fibers towards multifunctional actuator applications

Novel electrochemical fiber actuators based on graphene fiber/polypyrrole (GF/PPy) asymmetric structures have been prepared by a facile controlled electropolymerization of pyrrole (Py) on the GF. The fiber actuator is of high flexibility and durability, and can be further devised to fabricate multi-armed tweezers and net actuators.     

Analytical characterization of poly(pyrrole-3-carboxylic acid) films electrosynthesised on Pt, Ti and Ti/Al/V substrates

With the aim of developing a polymeric multilayer film for application in advanced biomaterials, as a first step poly(pyrrole-3-carboxylic acid) films (abbreviated as PPy-3-carbox) were electropolymerised from pyrrole-3-carboxylic acid solutions by cyclic voltammetry and chronoamperometry on platinum, titanium and Ti90Al6V4 substrates and characterised both electrochemically (cyclic voltammetry) and spectroscopically (X-Ray Photoelectron Spectroscopy, XPS). Electrochemical experiments showed that the potential range adopted for electropolymerization affects the polymer electroactivity, by analogy with unsubstituted polypyrrole. The combination of conventional and chemical derivation-XPS provided information on PPy-3-carbox surface structure, showing no significant difference between films grown on different substrates and an increase of the COOH groups amount (one group over three pyrrole rings, as an average) with respect to unsubstituted polypyrrole (PPy), as expected. Finally, a preliminary Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) investigation was performed in order to get further information on the polymer structure and electroactivity.     

基于静电吸附作用制备PPy/CNTs复合材料

通过添加十二烷基苯磺酸钠(SDBS), 在碳纳米管(CNTs)表面引入具有静电吸附作用的基团, 使吡咯单体附着于CNTs表面, 然后发生化学原位聚合, 得到了由片状聚吡咯(PPy)包覆CNTs所构成的PPy/CNTs复合材料, 开辟了一条易于工业化生产制备PPy/CNTs复合材料的途径. 所得材料和CNTs借助傅立叶变换红外光谱、扫描电子显微镜、透射电子显微镜等设备进行了成分和形貌的表征; 并将所得材料组装成电化学超级电容器, 进行了电化学性能测试. 研究结果表明, 加入SDBS后, 吡咯单体能很好地吸附于CNTs表面; CNTs的应用细化了PPy的颗粒, 改善了PPy的导电性能和机械性能, 使PPy/CNTs复合材料呈现出多孔状; 其电化学容量达到101.1 F·g-1(有机电解液), 是同样制备条件下所得纯PPy电化学容量(19.0 F·g-1)的5倍多, 约是所用纯CNTs电化学容量(25.0 F·g-1)的4倍.     

金与银电极表面甘氨酸分子吸附作用的SERS光谱研究

本文利用表面增强拉曼光谱(SERS)技术研究了甘氨酸在金与银基底表面的吸附作用特征。研究表明甘氨酸分子以COO-的不对称形式吸附于金电极表面,且NH2也是其可能的吸附位点;而在银电极表面,则主要是通过COO-的对称形式而吸附。在此基础上,进一步研究了电极电位与溶液酸碱性对吸附于粗糙化银电极表面甘氨酸分子吸附作用的影响。研究结果表明,甘氨酸分子中去质子化羧基的吸附作用受电位影响较小,而电位对-NH3+吸附作用的影响程度较大。另一方面,溶液pH值对银电极表面的甘氨酸分子吸附行为的影响也较为显著。随着溶液酸性减小羧基倾向于相对于电极表面平行吸附。这是由于随着溶液碱性增大氨基质子化程度的减小,有利于氨基在银电极表面吸附。这将改变分子的吸附构型使其更接近于电极表面。这些变化主要出现在pH值大于10的条件下。     

Synthesis and Characterization of Conductive Polypyrrole/Montmorillonite Nanocomposites via One-pot Emulsion Polymerization

A series of electrically conductive polypyrrole/clay nanocomposites were synthesized in this work by using one-pot emulsion oxidative polymerization of pyrrole in the presence of unmodified clay and using DBSNa as the surfactant. The effect of surfactant on the morphological and electrical properties of PPy also were investigated and discussed in some extent. Electrical conductivity of the samples was measured by using samples in which the conductive materials was sandwiched between two Ni electrodes at room temperature. PPy/MMT nanocomposites were characterized by using XRD, TEM, TGA and DSC means of investigation. Intercalated structures were determined for the nanocomposites as confirmed by XRD and TEM studies. Electrical conductivity of the nanocomposites was measured to be dependent to the clay content, and the methods of preparation. Measurement also showed that polymerization of pyrrole monomers pre-intercalated between the clay gallery spaces of the clay led to higher conductivity for the nanocomposite in the same level of clay content. Thermal property measurements showed a lower thermal decomposition rate for the PPy/MMT nanocomposites with respect to the PPy.     

Polypyrrole stretchable actuators

Here, we report a simple way to prepare stretchable polypyrrole (PPy)‐based actuator materials that can be operated over a wide dynamic strain range and generate useable actuation displacements and pressures. The stretchable actuators were prepared as a laminated composite of PPy and a gold‐coated roughened rubber sheet. By manipulating the corrugated surface of the rubber substrate, the stretchability of PPy was greatly improved. Gold‐coated rubbers could be stretched to 30% without significant change in electrical resistance. The corrugated PPy/gold/rubber laminates successfully showed ～1% of actuation strain even when prestretched to 24%. The actuation strains were smaller than for similar free‐standing PPy films and a detailed analysis of the effects of corrugation and of the rubber substrate are presented to predict actuation strain under various prestretch strains. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013     

Electrochemical preparation of effective and low cost catalyst for electrooxidation of ethanol

A nanocatalyst coating was prepared at surface of a glassy carbon electrode by electropolymerization of pyrrole by cycling the electrode potential between ?0.8 and 0.8 V (vs. Ag/AgCl). Then, polypyrrole film was potentiostatically coated with platinum nanoparticles at constant potential of ?0.2 V (vs. Ag/AgCl). The resulting electrode was denoted as GCE/PPy/Pt. This modified electrode was characterized by IR, SEM, TEM and EDX. The electrocatalytic oxidation of ethanol at the GCE/PPy/Pt has been investigated using cyclic voltammetric and chronoamperometric methods. The effects of various parameters on electrocatalytic oxidation of the ethanol, such as the thickness of PPy film, the amount of platinum nanoparticles, ethanol concentration, potential scan rate and working potential limit in anodic direction, were investigated. The kinetic of the ethanol oxidation is discussed on the GCE/PPy/Pt. The stability and reproducibility of this modified electrode were also studied.     

Electrochemical Deposition of Gold Metal Particles into 3‐Dimensional Polypyrrole Film Deposited on a Highly Oriented Pyrolytic Graphite

Electrochemical techniques and lateral friction microscopy (LFM) are exploited to characterize the deposition of gold metal particles onto the 3‐dimensional (3‐D) polypyrrole (PPy) film deposited on 2‐dimensional (2‐D) highly oriented pyrolytic graphite (HOPG) substrate surface in an aqueous solution involving 0.01 M pyrrole and 0.1 M LiClO₄? 3H₂O. Cyclic voltammetry is utilized to find the gold deposition potential onto the PPy film from 0.001 M KAu(CN)₂/KOH solution. The gold deposition potential is found to be in the range of ?1.2 V to ?1.4 V. Chronoamperometry is used to find out the nucleation and growth mechanism of gold metal particles onto PPy film. When the PPy film is thin, the mechanism follows the 3‐D instantaneous and moved towards 3‐D progressive as the film thickness increases. Considering the high resistance of thick PPy film and insulating and compact nature of the film at more cathodic potentials, it is suggested that the gold nuclei are formed first on the HOPG substrate surface, move to the PPy film surface and then distributed inside the PPy matrix. Since the friction of gold and the PPy film is different, the LFM is found to be an effective tool to see the distribution of gold particles in the domain boundaries of the PPy film.     

纳米级微带金电极上葡萄糖氧化酶的固定.性质及应用

实现了葡萄糖氧化酶以及葡萄糖氧化酶和电子传递媒体Fe(CN)^3^-~6同时在纳米级微带电极上的固定,用红外光谱和循环伏安对GOD/PPy微电极进行了表征, 研究了微带金电极上聚吡咯恒电位形成过程的动力学及葡萄糖氧化酶对其动力学过程的影响,探讨了微酶电极GOD/Fe(CN)^3^-~6/PPy对葡萄糖氧化的催化作用, 考察了PPy膜厚度和溶液中氧的存在对GOD/Fe(CN)^3^-~6/PPy微电极测定葡萄糖的影响.