Synthesis and characterization of polypyrrole by cyclic voltammetry at different scan rate and its use in electrochemical reduction of the simulant of nerve agents

In this study, polypyrrole (pPy) was in-situ electrosynthesized on gold electrode surface using four different scan rate variations such as 5, 10, 25 and 50 mV/s with the help of cyclic voltammetry. Scanning electron microscopy (SEM) characterization revealed a scan rate dependent surface morphology for the pPy modified electrodes. The surface functional groups and elemental composition of the modified electrodes were deduced using Raman spectroscopy and energy dispersive X-ray spectroscopy (EDS), respectively. These pPy modified electrodes were utilized to study the electrochemical behavior of the nerve agents’ simulant dimethyl methyl phosphonate (DMMP) in aqueous medium. These modified electrodes exhibited electrochemical parameters with DMMP depending on the scan rate used for the in-situ synthesis of pPy conducting polymer.     

Preparation of Au/ polypyrrole composite nanoparticles and study of their electrocatalytical reduction to oxygen with (without) lacasse

The colloids of Au/polypyrrole (AuPPy) composite nanoparticles were prepared by oxidizing pyrrole monomer with HAuCl₄ in a cetyltrimethylammonium bromide (CTAB) solution. Scanning electron microscopy (SEM) suggests the AuPPy nanoparticles in the form of regular spheres, approximately 200 nm in diameter. The resulting colloid of AuPPy composite nanoparticles strongly adheres to the surface of Au electrodes and exhibits better electrocatalytical reduction of oxygen than bare Au electrodes. It means that the complex procedures of centrifuge and wash are avoided. Also, no linker molecules are needed and the immobilization of nanoparticles is achieved easily in a single-step procedure. The experimental parameters were optimized with regard to the concentration of pyrrole and HAuCl₄. The direct electron transfer of laccase is observed after it is immobilized on AuPPy modified electrodes by glutaraldehyde. With the help of mediator 2,2′-azino-bis-(3-ethylbenzothiazoline-sulfonic acid) (ABTS), laccase electrode gives an electrocatalytical reduction wave of oxygen at least at 0.8 V. This material is an excellent choice for the design of metal nanoparticle modified electrodes or biosensors     

Effects of compaction pressure on the electrochemical properties of Mm0.3Ml0.7Ni3.55Co0.75Mn0.4Al0.3 metal hydride electrodes

In this work, the negative electrodes of the nickel-metal hydride rechargeable batteries were prepared at different compaction pressures. The maximum discharge capacities and cycle stabilities of the electrodes were measured by means of electrochemical method. The crystal structures and surface morphologies of the alloys were intensively studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM) combined with energy-dispersive spectrometry (EDS), respectively. Based on these observations, the effects of compaction pressure on the electrochemical properties of the electrodes were systematically investigated. The results showed that the electrode prepared at a compaction pressure of 25 MPa exhibited the best discharge capacity and better cycle stability.     

Electrochemical polymerization of pyrrole in BMIMPF6 ionic liquid and its electrochemical response to dopamine in the presence of ascorbic acid

Polypyrrole (PPy) film modified glassy carbon (GC) electrode was prepared by electrochemical polymerization in 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF₆) room temperature ionic liquid. The PPy film obtained in ionic liquid adhered on the electrode surface well and the properties of the PPy film have been characterized via UV–vis spectra and scanning electron microscopy (SEM). The electrochemical response of the PPy modified electrodes toward ascorbic acid (AA) and dopamine (DA) was investigated by differential pulse voltammetry (DPV). Well separated anodic peaks were observed at PPy electrode with peak separation (ΔE) of 200 mV at pH 6.2. Compared with PPy electrode prepared in aqueous solution, DA has a higher oxidation currents at the modified electrode prepared in ionic liquid. The oxidation peak potentials and currents were affected by the pH valuation and the film thicknesses.     

Erratum to “Mimicking photosynthesis: covalent [60]fullerene-based donor–acceptor ensembles” [Synth. Met. 147 (2004) 57–61]

Polypyrrole (PPy) nanowire modified electrode was prepared and its electrocatalytic behavior towards nitrate reduction was characterized_. The electrode surfaces were investigated by scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX). The electrocatalytic activity of modified graphite electrode was compared with graphite, copper (Cu) and platinum (Pt) electrode. The nitrite concentration produced at PPy modified electrode is lower than that at any other electrodes, and its changing tendency is opposite to any other electrodes. The PPy nanowire modified electrodes were further modified by electrodeposition of Cu. The results show that the produced nitrite concentration gets higher with the increase of Cu content. The primary experimental results show that the modified electrode has promise use in the remove of nitrate from water.     

稀土Ce掺杂Ti/Sb-SnO2电极的电化学性能及应用

采用热分解法制备Ti/Sb-SnO2电极和Ti/Sb-SnO2/Ce电极,采用扫描电子显微镜(SEM)、X射线衍射(XRD)仪和电化学实验技术对电极的表面形貌、物相组成和电化学性能进行表征。结果表明:Ti/Sb-SnO2电极表面形成了SnO2晶胞,经稀土Ce改性后SnO2晶粒明显细化,SnO2衍射峰强度变强且峰形宽化。Ti/Sb-SnO2/Ce电极峰电流值最大、表面稳定性增强和催化活性明显提高。在最佳工艺条件下,Ti、Ti/Sb-SnO2和Ti/Sb-SnO2/Ce电极对橙黄G目标污染物的去除率分别为46.6%、61.9%和94.9%,且降解过程均符合一级反应动力学模型,速率常数分别为0.0289、0.0633、0.1971min-1,Ti/Sb-SnO2/Ce电极的速率常数分别是Ti/Sb-SnO2电极的3倍,Ti电极的7倍,表明在电极表面涂层中掺杂稀土元素Ce可有效提高电极的性能。     

Simultaneous immobilization of cobalt tetrasulfonated phthalocyanine during electropolymerization of pyrrole in presence of surfactants: a study of film morphology and its conductivity

An attempt was made to electrochemically immobilize tetrasulfonated phthalocyanine (CoTsPc) into polypyrrole in presence of three types of surfactants (cationic, anionic, and neutral) during the polymerization of pyrrole in an aqueous solution with different potential regions. The surface characteristics of anodically/cathodically prepared electrodes with cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and Triton X-100 were investigated using the scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) measurements. The SEM and XPS measurements revealed the position and orientation of CoTsPc and surfactant, respectively, in the prepared films. The film conductivity was deduced from AC impedance and its conductivity values were found to be very low when compared to the literature results. The decrease of film conductivity in presence of the surfactant and CoTsPc could be associated with the fewer amounts of counter ions in the film and also the absence of conjugation for electron hopping within the film.     

Photoelectrochemical characteristics of AB5-type hydrogen storage alloy modified with SrTiO3 photocatalyst

Perovskite-type SrTiO3 powders were prepared by using strontium acetate, tetrabutyl titanate and sodium hydroxide via direct hydrolysis-precipitatlon process. AB5-type hydrogen storage alloy（HSA） electrodes modified with SrTiO3 powders were prepared and the photoelectrochemical characteristics of the as-prepared electrodes were investigated. The results of cyclic voltammograph show that the current of reduction peak increases remarkably under the light irradiation. The obvious photochargeable properties are obtained for the hydrogen storage alloys modified with Perovskite-type SrTiO3 powders. During photocharging process, the potential of the electrode shifts quickly to negative direction and a potential plateau occurs. HSA electrode modified with SrTiO3 powders prepared by direct hydrolysis-precipitation process gives the higher potential of about -0.90 V（vs Hg/HgO） under the light irradiation. SEM observation discloses that a large amount of microcracks occur on the surface of the electrode after photocharging process, which is caused by the formation of hydride in the bulk of electrode.     

溶胶凝胶法制备Sb掺杂Ti/SnO2 电极及其电催化性能

采用溶胶凝胶法制备了Sb掺杂Ti/SnO2电极,通过XRD,SEM,EDS及电化学测试、氧化物总量测试、加速寿命测试等技术手段,研究了Sb的掺杂对电极结构、形貌、电催化性能、使用寿命的影响。结果表明:Sb的掺入能有效改善电极的表面晶体结构和形貌,降低电极的苯酚氧化电位和液界电阻,提高电极的电催化效率;当制备的溶胶中锡锑比为9∶1时,制得的电极表面形貌平整、致密,稳定性和电催化效果最好。     

Li Doped Bismuth Oxide Nanorods for Electrochemical Detection of Tartaric Acid

A modified glassy carbon electrode (GCE) on Li doped Bi oxide nanorods has been prepared to study the electrochemical responses of tartaric acid. Electrochemical impedance spectroscopy shows that Li doped Bi oxide nanorods have high electron transfer ability between the electrolyte and the modified GCE. Two pairs of cyclic voltammogram peaks are located at–0.49, +0.04 V (cvp1 and cvp1′) and +0.68,–0.39 V (cvp2 and cvp2′), respectively. The linear range is 0.001–2 mM, and the detection limit is 0.69 and 0.77 μM for cvp1 and cvp2, respectively. The modified GCE on Li doped Bi oxide nanorods shows a wide linear range, a low detection limit, good repeatability and stability.     

Surface structure and catalytic activity of electrodeposited Ni-Fe-Co-Mo alloy electrode by partially leaching Mo and Fe

1 Introduction The chlorine alkaline industry and the production of hydrogen by electrolyzing water have disadvantages of high cost and energy consumption, so it is especially important to study and develop a high catalytic activity and good stability el…     

铝掺杂改性钛基PbO2电极性能研究

采用阳极电沉积技术制备了金属铝掺杂改性的Ti/PbO₂电极,通过表面粗糙度测量仪,扫描电镜,X射线衍射仪、线性极化扫描和交流阻抗谱电化学测试和加速寿命试验对铝掺杂引起PbO₂涂层电极的物理化学特性的影响进行分析,并对铝掺杂改性的Ti/PbO₂电极对苯酚模拟废水电催化氧化降解行为进行考察。结果表明,Al₃₊添加可使得Ti/PbO₂电极涂层结晶细化、沉积均匀致密,表面粗糙度明显降低,结瘤缺陷改善;铝掺杂改性的Ti/PbO₂析氧电位升高,电荷传递及催化性能提高,但呈非单调变化,其中添加3mM Al₃₊制备电极的析氧电位最高可达到2.09V,导电性优异,电催化性能最佳,电化学稳定性高,其强化寿命可达到460h,比未改性电极寿命提高了100h。铝掺杂改性的Ti/PbO₂电极对苯酚模拟废水具有良好的电化学氧化降解能力,180min处理后苯酚去除率最高可达到93.6%,COD去除率最大可达到73.6%。     

Preparation and characterization of electroless Ni-P-Fe3O4 composite coatings and evaluation of its high temperature oxidation behaviour

Ni-P coatings modified with synthetic magnetite were prepared by electroless technique from a Ni-P plating bath containing magnetite powder. The coatings morphology was studied by means of scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS). The corrosion resistance at room temperature of the Ni-P films modified with magnetite was evaluated by means of electrochemical impedance spectroscopy (EIS), where the composite films exhibited a better behaviour. The films resistance to high temperature oxidation was evaluated by cyclic oxidation tests, SEM/EDS and X-ray diffraction analysis (XRD), where the coating with iron oxides appears to be more protective.     

Low temperature brazing of components of radioelectronic equipment with a focused light beam

The objective of this study was an evaluation of the influence of the type of coating on the working life of electrodes when spot welding interstitial free steels with heat immersion coatings of the Zn pure (GI) and Zn–Fe alloy (GA) types. To do so, the electrode life was determined and the behaviour of the Zn of the coating evaluated on the contact plate/electrode surface during its working life, using ESM/EDS. As a result, it was confirmed that the working life of electrodes when welding GA steel was much higher than with GI steel. The electrode life was shown to be dependent on the fusion point of the coating. With the GI steel, part of the zinc layer moves to the edge of the electrode/plate contact at the start of the working life of the electrode. With the GA steel, Zn displacement was not confirmed throughout the whole working life of the electrode, due to the high-fusion point of the coating.     

离子液体[Emim]BF4改性二氧化铅电极的制备与表征

采用电沉积法制备了离子液体[Emim]BF₄改性PbO₂电极. 通过电化学氧化降解苯酚实验对电极催化性能进行了考察, 发现苯酚模拟废水的COD去除率符合一级反应动力学, [Emim]BF₄改性PbO₂电极的速率常数为0.00739 min_-1, 明显高于未改性PbO₂电极的速率常数0.00383 min_-1. 通过扫描电镜(SEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)对电极表面结构进行表征. 结果显示, 在加有离子液体[Emim]BF₄的电积溶液中沉积得到的钛基PbO₂涂层表面致密规整、结晶度高、晶格氧含量高. 通过莫特-肖特基(Mott-Schottky)曲线、稳态极化和线性扫描伏安法(LSV)考察了电极的电化学性质. 稳态极化实验表明改性电极的析氧过电位相比未改性电极有明显提高, 对莫特-肖特基曲线的分析表明, 改性电极表面氧空位含量相比未改性电极有很大降低. 通过与未改性电极结构和电化学性质的对比研究, 得出改性电极催化活性的提高主要是由于其氧空位含量较低, 从而降低了氧化物电极表面发生羟基自由基(?OH)向晶格氧(O_lat)转移的发生率.     

在LiCl-KCl-CeCl3熔盐中铝电极上欠电位沉积制备Al-Ce合金

在843K LiCl-KCl-CeCl3熔盐中活性铝电极上,研究了Ce(III)离子的电化学行为和欠电位沉积Al-Ce合金。对比循环伏安曲线发现,在Al电极上Ce(III)/Ce反应的氧化还原电势比在Mo惰性电极上更正;开路计时电位在金属铝和铈的沉积平台之间出现两个平台,这表明Ce(III)在Al活性电极上可以生成两种金属间化合物。以上结果在电化学机理上说明Ce(III)离子可以在Al电极上欠电位沉积形成金属间化合物。在该实验条件下通过恒电位电解,在Al电极上得到了Al-Ce合金,验证了理论分析的结果。经XRD表征,证实了形成AlCe和AlCe3两种合金;经SEM和EDS表征,证明了铈分布在Al电极表面厚度均一的合金镀层中（厚度28?m）。 关键词：LiCl-KCl熔盐;欠电位沉积;铝电极;Al-Ce合金     

Effects of sputtering conditions on electrochemical behavior and physical properties of Ni-Mo alloy electrode

1 Introduction Many transition metal alloys with binary and ternary compositions have been studied as hydrogen evolution reaction electrodes in water electrolysis[1- 6]. The activity of such metal alloys for the hydrogen evolution reaction depends on at l…     

(Cu,S)-ZnO纳米材料光电化学性能的研究

摘 要: 采用水热法制备纯ZnO、Cu-ZnO、S-ZnO及(Cu,S)-ZnO纳米粒。通过X-射线衍射仪(XRD)和扫描电子显微镜(SEM)对其晶型结构和表面形貌进行表征分析。利用电化学工作站测定其电化学性能。此外,以亚甲基兰溶液模拟废水,研究其光电催化性能。结果表明,掺杂剂的加入并没有改变其晶体结构,但晶粒尺寸明显变小,表面积增大,表面分布较为均匀。掺杂后,电极的电催化活性明显提高。其中,(Cu,S)-ZnO纳米粒的电化学性能最好,对亚甲基兰溶液的降解率最高,可达87.69%。     

Nano-diamond/Ni复合电刷镀层的组织形貌的研究

以45#钢为基体,制备了普通镍镀层和nano-diamond/Ni复合刷镀层,采用扫描电镜、能谱仪、X射线衍射仪和金相显微镜等设备对比研究了两种镀层的组织形貌。金相显微镜和扫描电镜分析结果表明,与普通镍镀层相比,nano-diamond/Ni复合刷镀层的表面更加平整、致密,组织更加细化;nano-dia-mond/Ni复合刷镀层表面呈典型的"菜花头"形状,弥散分布的纳米金刚石被镍包裹。能谱仪分析结果表明,nano-diamond/Ni复合刷镀层中纳米颗粒特征元素C的质量分数为7.37%。X射线衍射分析结果表明,随着纳米金刚石加入量的增加,镀层表面晶粒尺寸逐渐减小。     

Electro-catalytic degradation properties of Ti/SnO<Subscript>2</Subscript>–Sb electrodes doped with different rare earths

Ti/SnO₂–Sb electrode has a good effect on the removal of organic pollutants. But its short service life limits its large-scale application in industry. Electro-catalytic degradation performances and service life of the electrode can be significantly improved by doping rare earth (RE) ions into the oxide coating of Ti/SnO₂–Sb electrode. Ti/SnO₂–Sb electrodes doped with different RE elements (Ce, Dy, La, and Eu) were prepared by the thermal decomposition method at 550 °C. Electro-catalytic degradation performances of electrodes doped with different RE elements were evaluated by linear sweep voltammetry (LSV) and Tafel curves. During the electrolysis, the conversion of p-nitrophenol was performed with these electrodes as anodes under galvanostatic control. The structures and morphologies of the surface coating of the electrodes were characterized by scanning electron microscope (SEM). The results demonstrate that the electro-catalytic degradation performances of Ti/SnO₂–Sb electrodes are improved to different levels by doping different RE ions. Improved Ti/SnO₂–Sb electrodes by the introduction of different RE have higher oxygen evolution potential, better electro-catalysis ability, better coverage, and longer electrode life.