铂-氧化铈/聚苯胺/聚砜复合膜电极的制备及对甲醇的电催化氧化

采用电化学聚合法制备了掺杂CeO2纳米粒子的聚苯胺(PAN)/聚砜(PSF)复合膜电极,在其上电沉积铂粒子,制得了铂-氧化铈/聚苯胺/聚砜的复合膜修饰电极。 复合膜的形貌和化学组分通过冷场发射扫描电子显微镜（Cold FE-SEM）和能量散射X射线谱（EDS）进行了表征,用循环伏安法和电化学交流阻抗法考察了复合膜电极对甲醇的电催化氧化性能。 结果表明,复合膜的双层多孔结构使铂粒子与CeO2粒子在复合膜内层的多孔聚苯胺上均匀沉积,粒子平均尺寸约为80 nm;CeO2为铂质量的7%时,铂-氧化铈/聚苯胺/聚砜复合膜修饰电极对甲醇有很好的电催化氧化性能和高的稳定性。     

Study on the Impedance Characteristic and Electrocatalytic Activity of Platinum‐Modified Polyaniline Film

The composite electrode of platinum‐modified polyaniline film is formed in 0.5 M H₂SO₄ + 3 mM H₂PtCl₆ solution by cyclic potential or constant potential deposition of platinum particles in polyaniline film. To make a comparison, the polyaniline film with the same initial thickness and structure is also treated with the cyclic potential or constant potential polarization in 0.5 M H₂SO₄ solution. The electrochemical impedance spectroscopy (EIS) of the composite electrode of platinum‐modified polyaniline film is studied in sulfuric acid solution and compared with the EIS of the polyaniline film without platinum dispersion. The results show that the different modes of potential polarization affect greatly the nature and distribution of the platinum particles, instead of the structure of the polyaniline film (matrix). The electrode reaction kinetics and mass transport process parameters involving charge transfer resistance (R_ct), double layer capacitance (C_dl), constant phase elements (CPE) and Warburg impedance in platinum substrate/platinum‐modified polyaniline film/solution interface are discussed on the basis of the interpretation of the characteristic impedance spectra and connected to the electrocatalytic activity on the oxidation of methanol molecules.     

聚苯胺/聚砜复合材料的制备及其超级电容性能

通过化学聚合法,制备出盐酸掺杂聚苯胺（PANI）,将其与聚砜（PSF）溶液混合,定量滴加到玻碳电极上制得PANI/PSF复合膜电极。 采用扫描电子显微镜、红外光谱以及X射线衍射对其结构和形貌进行表征。 根据循环伏安曲线、恒电流充放电曲线和电化学阻抗,研究了其作为电极的超级电容性能。 结果表明,多孔结构的PANI/PSF复合材料具有良好的电容性能,其比电容可达到497 F/g,并且该超级电容器具有较小的内阻和较好的循环稳定性。     

Characterization of stainless steel electrode modified by a thin film of polyaniline containing pt particles and its electrocatalytic activity for methanol oxidation

The catalytic behavior of stainless steel (SS) electrode modified by a thin film of polyaniline (PANI) containing platinum particles was studied for electrooxidation of methanol and compared with a platinated Pt/PANI electrode in acidic aqueous solution. Cyclic voltammetry (CV), chronoamperometry, CO stripping techniques were used to investigate electrochemical properties and electrocatalytic activity of SS/PANI/Pt and Pt/PANI/Pt electrodes. The morphology and particle size of Pt catalysts were characterized by Transmission Electron Microscopy (TEM) measurement. The effects of various parameters such as thickness of polymer film, medium temperature and stability of the modified electrodes on methanol oxidation were also investigated. The results indicated that the modified SS electrode exhibited a considerably high electrocatalytic activity on the methanol oxidation as well as the modified Pt electrode.     

The carbon nanotubes-polyaniline composites and their effect on catalytic properties of deposited catalysts

Composites of functionalized single-wall carbon nanotubes and polyaniline are deposited onto electrodes by in situ electrochemical polymerization. Their electrochemical behavior and differential capacitance are studied by cyclic voltammetry, electrochemical impedance spectroscopy, and chronovoltamperometry. The differential capacitance of the composite electrode exceeds that of pure polyaniline film deposited onto electrode, which can be explained by the nanotubes’ loosening effect on the polyaniline structure. The composite-electrode capacitance is as large as 1000 F g⁻¹ or higher. Thus obtained composite films were used as a support for deposited platinum-ruthenium catalyst. The Pt-Ru structure and catalytic properties in the methanol oxidation reaction are studied. It is shown that the specific current of methanol oxidation at Pt-Ru is larger by a factor of 7–15 than those measured when pure polyaniline, pure carbon nanotubes, or standard Vulcan XC-72 carbon black are used as supports. It is found that the catalytic activity is the same for all studied supports, provided the current is reduced to the unit of Pt-Ru true surface area. Thus, the observed large catalytic effect is associated with the structure and high dispersivity of the electrodeposited metals incorporated to the single-wall carbon nanotubes-polyaniline composite.     

载铂微粒的聚苯胺薄膜电极对甲醇的电催化氧化

用电化学方法制备的载有金属铂微粒的聚苯胺（ＰＡｎ）膜电极对甲醇在硫酸中的电化学氧化具有很高的催化活性。电极材料中的铂微粒是沿着聚苯胺的纤维分布的，而且主要沉积在ＰＡｎ膜的表面。     

Investigation and comparison of the electrochemical behavior of some organic and biological molecules at various conducting polymer electrodes

Electrodes modified by the electrodepozition of conducting organic polymers such as poly(3-methylthiophene)(PMT), polypyrrole (PPY) and polyaniline (PAN) were used as chemical sensors for voltammetric analysis and flow injection detection of some organic and biological molecules. The electrochemical behaviors of catechol, ascorbic acid, hydroquinone, dopamine, epinephrine, acetaminophen and p-aminophenol were examined by differential pulse voltammetry. The electrochemical behavior of these molecules at different electrodes was compared and the effects on behavior of electrolyte type and its pH and the film thickness were systematically examined. The results showed that the proposed modified surface catalyzes the oxidation of these compounds. Electrocatalytic 'efficiency' decreases in order of poly-3-methylthiophene, polypyrrole and polyaniline. Voltammetric peak positions were affected by the nature of the electrolyte and its pH. Also, the effect of increasing film thickness was to observe increased peak heights. Polymer coated electrodes were also used in an amperometric detector for flow injection analysis of most of the these compounds. The responses of the polymer electrode were 5-15 times larger as compared with those of bare platinum. PMT showed improved performance as an amperometric detector for flow injection analysis systems over other types of polymer electrodes. Detection limits as low as 10(-8)-10(-9) M were achieved using the PMT, compared with 10(-6)-10(-8) M using platinum electrodes. In the flow injection analysis, with increasing molecular weight of analyte molecules was to observe decreased peak heights.     

杂多酸修饰的电极对于甲醇电氧化的促进作用

采用杂多酸修饰光滑铂电极,研究其对甲醇电催化氧化的作用,发现与未修饰光滑铂电极相比,分别经磷钨酸和硅钨酸修饰的电极上甲醇电催化氧化速率明显增加.     

Electrocatalytic oxidation of methanol onto platinum particles decorated nanostructured poly (1,5-diaminonaphthalene) film

In this work, platinum particles decorated nanostructured poly (1,5-diaminonaphthalene) modified glassy carbon electrode (Pt/Nano-PDAN/MGCE) is prepared. The composite catalysts are characterized by scanning electron microscopy, energy dispersive spectroscopy, and electrochemical methods. The electrochemical methanol oxidation reaction is studied at the surface of this modified electrode. At same Pt loading, the Pt/Nano-PDAN/MGCE can act as higher efficient catalyst for methanol oxidation than that Pt/MGCE. Then, the influence of some parameters such as potential scan rates, switching potential, and methanol concentration on its oxidation as well as long-term stability of the modified electrode have studied by electrochemical methods. Also, ability of the modified electrode toward electrocatalytic oxidation of formaldehyde as an intermediate in methanol oxidation has been investigated.     

Composite electrodes consisting Pt nano-particles and poly (aminophenols) film on pre-treated aluminum substrate as electrocatalysts for methanol oxidation

Electrochemically platinum plated aluminum (Al/Pt) was used as an electrode substrate for the electropolymerization of aminophenols and fabrication of composite electrodes based on platinum nano-particles. The poly(o-aminophenol) (PoAP), poly(m-aminophenol) (PmAP), and poly(p-aminophenol) (PpAP) were synthesized on the Al/Pt electrode, and further modification was performed by deposition of platinum nano-particles onto polymer matrixes. The electrochemical and morphological characteristic of the composed electrodes were carried out by cyclic voltammetry and scanning electron microscopy, respectively. The electrocatalytic oxidation of methanol on the composite electrodes was studied by cyclic voltammetry in 0.1 M sulfuric acid as supporting electrolyte. It was found that the Al/Pt/PoAP electrode incorporated Pt nano-particles (Al/Pt/PoAP/Pt) exhibits a higher electrocatalytic activity for the oxidation of methanol than the Al/Pt/PmAP/Pt and Al/Pt/PpAP/Pt electrodes. On the other hand, a higher catalytic current for methanol oxidation was found on the Al/Pt/PoAP/Pt electrode in comparison to bulk Pt and Al–Pt (Al with 0.2 mg cm⁻² of Pt particles) electrodes. The effects of various parameters such as thickness of the polymer film, concentration of the monomer, Pt loading method and the Pt amounts, concentration of the methanol, and the medium temperature were studied on the electrooxidation of methanol. The long-term stability of the modified electrode has also been investigated.     

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.     

Oscillatory electrocatalytic oxidation of methanol on an Ni(OH)2 film electrode

A film of Ni(OH)₂ deposited cathodically on a roughened nickel substrate consists of even nanoparticles, which were characterized by atomic-force microscopy (AFM). The mechanism of potential oscillations in the electrocatalytic oxidation of methanol on this film electrode in alkaline medium was studied in situ by means of Raman spectroscopy in combination with electrochemical measurements. The redox change of the nickel hydroxide film, the concentration distribution of methanol in the diffusion layer, and the oxidation products of methanol were characterized in situ by time-resolved, spatial-resolved, and potential-dependent Raman spectroscopy, respectively. Electrochemical reactions, i.e. methanol oxidation and periodic oxygen evolution, coupling with alternately predominant diffusion and convection mass transfer of methanol, account for the potential oscillations that occur during oxidation of methanol above its limiting diffusion current. This mechanism is totally different from that of methanol oxidation on platinum electrodes, for which surface steps, i.e. formation and removal of CO_ad, are essential.This work is dedicated to Professor Gyorgy Horanyi on the occasion of his 70th birthday in recognition of his numerous contributions to field of electrochemical oscillations and electrocatalysis at Ni-hydroxide electrodes.     

铂粒子修饰单壁碳纳米管/聚苯胺复合膜对甲醛的电催化氧化

在溶有单壁碳纳米管(SWNTs)的苯胺溶液中, 通过电化学共聚合法成功制备了单壁碳纳米管(SWNT)/聚苯胺(PANI)复合膜. 用电沉积法将铂沉积到SWNT/PANI复合膜上. 样品的成分和形貌分别用XRD和SEM表征. 四探针和电化学交流阻抗的研究表明被PANI包裹的SWNTs整齐地排列在复合膜中, 从而提高了复合膜的电导率, 促进了电荷转移. 循环伏安(CV)说明Pt修饰的SWNT/PANI复合膜对于甲醛氧化具有良好的电催化活性及稳定性. 研究结果表明SWNT/PANI复合膜是一种非常好的催化剂载体, 有着广泛的应用前景.     

碳纳米管/聚苯胺/铁氰化镍复合膜的电化学共聚制备与电容性能

采用循环伏安一步共聚法在碳纳米管修饰的铂基体上制备了电活性碳纳米管/聚苯胺/铁氰化镍(CNTs/PANI/NiHCF)复合膜.用傅立叶变换红外(FT-IR)光谱、X射线能谱仪(EDS)和扫描电镜(SEM)研究了复合膜组成及其表面形貌,并用循环伏安(CV)、恒电流充放电和电化学阻抗(EIS)等测试了复合膜的循环稳定性与电化学容量性能.研究表明:CNTs/PANI/NiHCF复合膜为三维多孔有序的网络状结构,PANI和NiHCF以纳米颗粒形式存在并沿CNTs均匀分布;在电流密度为2mA.cm-2时,CNTs/PANI/NiHCF复合膜的比容量高达262.28F.g-1,比能量为29.51Wh.kg-1,电流密度为10mA.cm-2时比功率可达10228.61W.kg-1;在2000次循环充放电过程中,复合膜的电容量仅衰减19.92%,电荷充放电效率一直保持在99%以上.CNTs/PANI/NiHCF有机-无机杂化膜具有良好的功率特性和快速充放电能力,是一种优异的超级电容器材料.     

Polyaniline/poly(vinyl alcohol) (PAN/PVA) composite films: the synergy of film structural stiffening, redox amplification, and mobile species compositional dynamics

In this work, we report an unexpected but significant improvement of the redox behavior of conducting polyaniline (PAN) films by trapping intrinsically nonconducting poly(vinyl alcohol) (PVA) in the matrix of the polymer acting as stiffening and/or cross-linking agents. Film structural stiffening of PAN/PVA inclusion was studied in relation to film compositional dynamics. PAN and PAN/PVA composite films were potentiodynamically deposited using high-frequency electrochemical quartz crystal microbalance under electrochemical potentiodynamic control. From the simultaneously obtained measurements of nanogravimetric and cyclic voltammetric data, it has been found that the presence of PVA in the deposition solution increased the rate of PAN film growth as a function of PVA concentration. Characterization of the resultant composite films in monomer-free acidic electrolyte solutions showed significantly enhanced redox behavior of PAN/PVA composite films (with different PVA contents) compared to pure PAN by a factor of ～2–4. For the study of structure–composition relationships of composite polymer films, fluxes of instantaneous mobile species dynamics (ion/solvent) as a function of film redox conversion and potential cycling were correlated with film structural stiffening and the observed unusual redox enhancement of PAN/PVA composite films. Using various experimental timescales, we were able to resolve bound (associated with ion transfer) and free solvent compositional dynamics (associated with thermodynamic activity balance).     

电催化甲酸氧化中钯微粒与聚苯胺的相互作用

采用电化学、ＸＰＳ和拉曼光谱研究钯微粒修饰聚苯胺（ＰＡＮ（Ｐｄ）电极对甲酸氧化的电催化行为。由于钯与ＰＡＮ的相互作用，钯微粒在所研究的电位区间可稳定地固定于ＰＡＮ中，且甲酸在钯上的氧化明显地抑制ＰＡＮ的氧化降解，使ＰＡＮ（Ｐｄ）电极电催化甲酸氧化反应具有高的稳定性和活性。     

Electrocatalytic oxidation of methanol on Ni modified polyaniline electrode in alkaline medium

Electrolytically deposited Ni on polyaniline film covered carbon paste electrode (Ni/PANI/CPE) was used as anode for the electrooxidation of methanol in alkaline medium. The electrochemical behavior and electrocatalytic activity of the electrode were studied using cyclic voltammetry, impedance spectroscopy, chronomethods, and polarization studies. The morphology and composition of the modified film were obtained using scanning electron microscope and energy dispersive X-ray analysis techniques. The electrooxidation of methanol in NaOH was found to be more efficient on Ni/PANI/CPE than on bare Ni, electrodeposited Ni on Pt, Ni on glassy carbon, and Ni on CPE substrates. Partial chemical displacement of dispersed Ni on PANI with Pt or Pd further improved its performance towards methanol oxidation.     

Synthesis and Properties of Composite Polyaniline–Nafion Films on Platinum

Information on the synthesis of a polyaniline film on platinum covered with a Nafion film is obtained. The effect of electrochemical conditions on the synthesis is studied. The relationship between these conditions and properties of obtained composite polyaniline–Nafion films is revealed. It is established that on platinum covered with a Nafion film in certain electrochemical conditions in a polyaniline solution there occurs the formation of a composite polyaniline–Nafion film. The polyaniline in the film mainly retains its individual properties. It is demonstrated that the mechanism of the synthesis of polyaniline in the composite film substantially differs from that in the case of the formation of a film on platinum.     

Polymer films on electrodes: Part II. Film structure and mechanism of electron transfer with electrodeposited poly(vinylferrocene)

The structure and properties of electrodeposited poly(vinylferrocene) (PVF) films on platinum electrodes (PVF/Pt) were examined by electron microscopy, X-ray photoelectron spectroscopy, various electrochemical techniques and measurements of the film resistance. The data were consistent with a mechanism in which the polymer films are permeable to dis-solved reactants. A theoretical treatment of this situation for chronoamperometry is presented. The oxidation and reduction of a variety of dissolved reactants with redox potentials far removed from that of the PVF/PVF⁺ system at PVF/Pt occurred by diffusion of the electroactive species through the polymer film and subsequent reaction at the platinum surface.     

Formation Optimization and Electrocatalytic Properties of Platinum-Modified Polyaniline Films

The electrocatalytic properties of platinum particles incorporated into polyaniline films are investigated for oxidation of methanol in sulfuric acid electrolyte. It is found that the oxidation of methanol depends greatly on the nature of both polyaniline matrix and platinum particles which can be optimized by the electrochemical formation conditions, such as cycle numbers, deposition mode, and rotation rate.