Electrochemical fabrication of polyaniline films containing gold nanoparticles deposited on titanium electrode for electro-oxidation of ascorbic acid

Polyaniline films prepared on titanium were employed as substrate for the electrodeposition of gold. The modified electrode was used as anode for the electro-oxidation of ascorbic acid. The electrochemical behavior and electro-catalytic activity of Au/PAni/Ti electrode were characterized by cyclic voltammetry. The morphology of the polyaniline film and gold coating on PAni/Ti electrode were characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) techniques, respectively. Results indicated that gold nanoparticles were homogeneously dispersed on the surface of polyaniline film. The electro-oxidation of ascorbic acid is found to proceed more facile on Au/PAni/Ti electrode than on bare gold electrode. The irreversible oxidation current of ascorbic acid exhibits a linear dependence on the ascorbic acid concentration in the range of 1–5 mM.     

An easy route to prepare carbon black-silver hybrid catalysts for electro-catalytic oxidation of hydrazine

Carbon black-silver hybrid catalysts were easily synthesized by a mixing method of acid-oxidized carbon black and the colloidal dispersion of silver nanoparticles. The silver colloidal dispersion was pre-synthesized by a chemical reduction of silver nitrate by dimethyl sulfoxide in the presence of trisodium citrate dihydrate as capping agents. In the mixing method, approx. 6.0 nm diameters of silver nanoparticles with face-centered cubic crystal structures are highly dispersed on the acid-oxidized carbon blacks due to the surface reactivity resulting from the enhancement of oxygen-containing functional groups. The hybrid catalysts were examined for electro-catalytic activity towards oxidation of hydrazine. The results clearly show that the carbon black-silver hybrid catalysts are highly active for electro-catalytic oxidation of hydrazine.     

Titanium and platinum modified titanium electrodes as catalysts for methanol electro-oxidation

Electro-oxidation of methanol was studied on titanium and platinum modified titanium electrodes (Pt/Ti). Platinum was electro-deposited on Ti by potentiostatic and galvanostatic techniques. Electrodes prepared by the galvanostatic technique showed enhanced catalytic activity towards methanol oxidation in NaOH solution compared to those prepared by the potentiostatic method. Scanning electron microscopy and energy dispersive X-ray analysis were used to characterize the surface morphology and percent composition of Pt to Ti on the electrode surface. The catalytic activity of Pt/Ti electrode is much higher than that of Pt/Pt, bulk Ti and of pure Pt, in addition to minimizing the poisoning effect. In 3.0 M NaOH and in the presence of 2.0 M MeOH, the oxidation peak current density value of methanol after the 50th cycles reached 99.4% of its value at the first cycle for electrodes prepared by the galvanostatic method compared to 94.7% for electrodes prepared by the potentiostatic method. Polarizing the modified electrode at the hydrogen evolution potential region for a certain time was found to enhance the catalytic oxidation of methanol, while the presence of thick Ti-oxide as well as Ti-hydride inhibited the process.     

Application of titanium oxide nanotube films containing gold nanoparticles for the electroanalytical determination of ascorbic acid

Au/TiO₂/Ti electrodes have been prepared by galvanic deposition of gold particles on TiO₂ nanotube substrates. Titanium oxide nanotubes are fabricated by anodizing titanium foil in a Dimethyl Sulfoxide electrolyte containing fluoride. The scanning electron microscopy results indicated that gold particles are homogeneously deposited on the surface of TiO₂ nanotubes. The TiO₂ layers consist of individual tubes of about 40-80 nm diameters. The electro-catalytic behavior of Au/TiO₂/Ti and flat gold electrodes for the ascorbic acid electro-oxidation was studied by cyclic voltammetry. The results showed that the flat gold electrode is not suitable for the oxidation of ascorbic acid. However, the Au/TiO₂/Ti electrodes are shown to possess catalytic activity toward the oxidation reaction. Catalytic oxidation peak current showed a linear dependence on the ascorbic acid concentration and a linear calibration curve is obtained in the concentration range of 1-5 mM of ascorbic acid. Also, determination of ascorbic acid in real samples was evaluated. The obtained results were found to be satisfactory. Finally the effects of interference on the detection of ascorbic acid were investigated.     

含Mn中间层钛基二氧化锡电催化电极的性能

采用高温热氧化方法制备了含Mn中间层的钛基二氧化锡电催化电极Ti/Mn/SnO2.采用SEM、EDX以及XPS等检测方法对电极表面涂层的形貌、元素组成及元素化学态进行了分析,研究了所制备Ti/Mn/SnO2电极电催化氧化降解苯酚的性能.结果表明,Mn中间层的引入降低了电极对苯酚的电催化降解活性,使电极的使用稳定性大为提高.含Mn中间层的存在,可防止电化学反应过程中析出的氧向基体的扩散,离子对Mn2 /Mn4 与Sn2 /Sn4 的存在改变了SnO2电极表面催化剂的组成和结构,导致电极性能变化.     

铁氰化物掺杂聚苯胺复合材料的制备和表征

以ITO导电玻璃为工作电极,在三电极系统中,采用循环伏安法制得聚苯胺薄膜,聚苯胺/铁氰化铜(CuHCF),聚苯胺/铁氰化钴(CoHCF),聚苯胺/铁氰化铈(CeHCF)复合材料。通过利用C-V、SEM、EDS、XRD、FT-IR等方法对导电复合物进行表征和性能研究。实验结果表明,制备复合物的最佳电解液浓度为0.02mol/L苯胺+0.002mol/L金属离子+0.01mol/L铁氰化钾+0.5mol/L H2SO4;聚苯胺与铁氰化物很好地键合在一起,聚苯胺/铁氰化钴复合材料的电化学性有进一步的提高,具有纳米粒子特性和独特的片状粒子结构;而聚苯胺/铁氰化铜和聚苯胺/铁氰化铈的电化学性能高于聚苯胺本体,粒子间有较大的空穴现象。     

钛基银镍电极在碱性溶液中对乙醇氧化的电催化活性

以硝酸银、硫酸镍和水合肼为原料,以钛为基体,采用水热法首先合成了钛基银电极（Ag／Ti）,再以此电极为基体,采用水热法合成了银基镍电极（Ni／Ag／Ti）。SEM图像表明,金属镍以纳米球状形式沉积于银表面。利用循环伏安（CV）和恒电位阶跃（CA）等电化学方法,研究了在Ni／Ag／Ti电极和Ni／Ti电极上,乙醇在1MNaOH溶液中的电化学氧化行为。结果表明,Ni／Ag／Ti电极对乙醇的电化学氧化表现出更高的电流密度（87mA／cm^-2）。     

Synthesis of multi-walled carbon nanotube supported nickel catalysts by hydrazine reduction and their electrocatalytic activity on ethanol electro-oxidation

Multi-walled carbon nanotube (MWCNT) supported nickel (Ni) catalysts were chemically synthesized via a hydrazine reduction process with addition of cetyltrimethylammonium bromide (CTAB) as a special additive. As evidenced by field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and high-revolution transmission electron microscope (HR-TEM), the Ni nanoparticles (NPs) deposited on the sidewalls of MWCNTs were found to be face-centric cubic (fcc) crystal structure, and dispersed homogenously with a sharp particle size distribution centered at around 20 nm of diameter. Electro-oxidation of ethanol on MWCNT/Ni catalysts was investigated by cyclic voltammetry (CV) measurement. The MWCNT/Ni catalysts showed excellent electro-catalytic activity for the oxidation of ethanol in alkaline solution.     

钛基Co中间层SnO2电催化电极的制备及性能研究

为提高钛基二氧化锡电极的稳定性,设计并制备了含Co中间层的钛基二氧化锡电催化电极Ti/Co/SnO2,以苯酚为目标有机物,考察了所制备Ti/Co/SnO2电极电催化氧化降解苯酚的性能,并采用SEM、EDX以及XPS等检测方法分析了Ti/Co/SnO2电极表面的形貌、元素组成及元素化学态.研究结果表明,含有中间层的Ti/Co/SnO2电极其使用寿命较不含中间层的钛基二氧化锡电极Ti/SnO2大幅度提高,但其对苯酚的电催化降解活性有所下降,氧化还原电对Co2 /Co3 的存在是所制备Ti/Co/SnO2电极稳定性及电催化活性改变的主要原因.     

Ni-Co/Ti催化剂制备及其对葡萄糖的电催化氧化

采用水热法制备了一种新型多孔镍钴修饰钛电极(Ni-Co/Ti)。利用循环伏安、电位阶跃等电化学技术研究了碱性溶液中Ni-Co/Ti电极对葡萄糖氧化的电催化活性。双电位阶跃分析表明,葡萄糖在该体系中的扩散系数为6.50×10-6cm2/s,葡萄糖在Ni-Co/Ti电极电化学氧化反应速率常数为3.57×104cm3/(mol.s)。实验表明,Ni-Co/Ti电极对葡萄糖氧化具有优异的电催化活性。     

聚苯胺/TiO2复合纳米膜电极的制备及其光电性能

采用原位化学氧化法,在酸性TiO2溶胶中未加分散剂制备了聚苯胺修饰的TiO2稳定溶胶,并以涂刮法在柔性导电塑料薄膜上成膜。利用FT-IR、XRD、TEM、选区电子衍射、紫外-可见光谱、光电流-电压曲线对所制备的复合溶胶及复合膜进行了表征。结果表明TiO2与聚苯胺之间实现了结构上的复合,聚苯胺的引入改善了TiO2膜对太阳光的利用率,提高了TiO2膜的光电响应性能。这种用复合溶胶制备聚苯胺/TiO2复合膜的方式扩大了成膜基底的范围。     

CTAB assisted immobilization of RuO2 nanoparticles on graphene oxide for electrochemical sensing of hydrazine

A novel method has been presented to modify glassy carbon electrode (GCE) with graphene oxide (GO) nanocomposite without introducing any electrode binder such as chitosan and Nafion. First, modify GCE with RuO₂ nanoparticles which have been dispersed in cetyltrimethyl ammonium bromide (CTAB) aqueous solution. Then, highly adhesive RuO₂/CTAB/GO nanocomposite membrane formed on GCE by immersing RuO₂/CTAB modified GCE in GO suspension. CTAB plays significant roles not only in the preparation of the nanocomposite but also in the immobilization of nanocomposite on GCE surface. First, CTAB was used as the dispersant of RuO₂ nanoparticles. Second, CTAB acted as the molecular linker to bind RuO₂ nanoparticles on graphene sheets. Third, CTAB formed CTAB/GO nanocomposite which is highly adhesive on the surface of electrodes such as GCE and ITO (indium tin oxide). The obtained RuO₂/CTAB/GO/GCE shows excellent electrocatalytic ability towards the oxidation of hydrazine. The oxidation of hydrazine on RuO₂/CTAB/GO/GCE is an adsorption-controlled process and the oxidation current is linear with the concentration of hydrazine in the range of 1 × 10^?5～1 × 10^?3 M with a detection limit of 2.3 × 10^?6 M. The application of this sensor in the sensing of hydrazine in real water samples confirmed its reliability and accuracy.     

Fabrication of self-assembled polyaniline films by doping-induced deposition

The ultrathin films of polyaniline (PAni)/poly (styrenesulfonic acid)(PSSA) were fabricated via a novel self-assembling process by alternately immersing the substrates into dilute PAni solution in N-methylpyrrolidinone (NMP) and the aqueous solution of PSSA. The process was characterized by UV–Vis absorption spectroscopy. It was found that the oxidation state of polyaniline in single monolayers was dependent on the thickness of the film. The self-assembling mechanism was based on the acid-base reaction between PAni and PSSA. The thickness of the films can be easily manipulated at nanometer scale by controlling the solution chemistry and recycling times. The resulting films are uniform and adhere strongly to the substrates.     

Sb掺杂钛基SnO2电极的制备、表征及其电催化性能研究

采用电沉积 热氧化法制备了含有中间层的Sb掺杂钛基SnO2 电催化电极(Ti/SnO2),采用SEM、EDX以及 XRD 等检测方法对所制备电极的表面形貌、元素组成及结构进行分析,并以苯酚为目标有机物,研究所制备电极对有机污染物的电催化降解能力。研究结果表明所制备 Ti/SnO2 电极可在较短时间内将苯酚彻底降解,其较大的真实表面积以及电极中间层的存在是所制备电极性能提高的重要原因。阳极极化曲线扫描(LSV)的分析结果表明所制备的 Ti/SnO2电极具有较高的阳极析氧电位,有利于有机物的阳极氧化降解。     

Electro-catalytic degradation of phenol on several metal-oxide anodes

Three kinds of Ti-based multilayer metal-oxide electrode, including Ti/SnO(2)+Sb(2)O(3)/PbO(2), Ti/SnO(2)+Sb(2)O(3)/MnO(x) and Ti/SnO(2)+Sb(2)O(3)/RuO(2)+PbO(2) electrodes, were prepared by thermal decomposition, and SnO(2)+Sb(2)O(3) coatings were produced with a polymeric precursor method (PPM). The conversion of phenol was carried out with these electrodes as anodes under galvanostatic control. Samples during the electrolyses were characterized with UV-vis spectra and chromatography, and chemical oxygen demand (COD) and instantaneous current efficiency (ICE) for phenol degradation were also determined. The results show that phenol can be oxidized and degraded for all of the three anodes, and the oxidation reactions of phenol follow first-order kinetics, but there are considerable differences in the effectiveness and performance of electro-catalytic degradation. Phenol can be degraded relatively fast on the Ti/SnO(2)+Sb(2)O(3)/PbO(2) anode and the degradation rate of phenol is slower with the Ti/SnO(2)+Sb(2)O(3)/MnO(x) electrode, and the slowest with the Ti/SnO(2)+Sb(2)O(3)/RuO(2)+PbO(2) electrode, whose apparent rate constants are 2.49 x 10(-2), 1.42 x 10(-2) and 9.76 x 10(-3) min(-1), respectively. The rates of electro-catalytic degradation relate to oxygen evolution potential, and the higher the oxygen evolution potential, the better the performance of electro-catalytic degradation. The potential for oxygen evolution at the Ti/SnO(2)+Sb(2)O(3)/PbO(2) anode is highest, then Ti/SnO(2)+Sb(2)O(3)/MnO(x), following Ti/SnO(2)+Sb(2)O(3)/RuO(2)+PbO(2). The accelerated life tests at 60 degrees C and in 1.0 mol L(-1) aqueous H(2)SO(4) with an anodic current density of 4.0 Acm(-2) show that the service life is prolonged when the SnO(2)+Sb(2)O(3) interlayer coating are inserted between Ti substrate and active layers.     

Electrochemical Behavior of CoSb3-based Electrodes Using Binary PAni/PVDF Binder

The polyaniline （PAni）/polyvinylidene fluoride （PVDF） hybrid was served as a novel binder for CoSb3-based alloy electrode. The effect of PAni content on the electrochemical performances of the alloy electrode was investigated. It was found that the CoSb3 electrode using the binary PAni/PVDF binder exhibits higher reversible capacity than that using the single PVDF binder, especially in the initial cycles. As a result, the PAni/PVDF hybrid could be a promising binder for the alloy electrode.     

Electrocatalytic activity of silver modified gold film for glucose oxidation and its potential application to fuel cells

The electrocatalytic activity of the submonolayer silver modified gold film electrodes for the glucose oxidation in alkaline solution and the influences of the electrode size, the glucose concentration and the supporting electrolyte concentration on the reaction were investigated using cyclic voltammetry. The performance of a fuel cell utilizing the glucose oxidation was also evaluated. Gold film electrodes of large size were prepared by evaporating gold onto micas. The submonolayer modification of gold electrodes by silver underpotential deposition resulted in about 0.1 V negative shift in peak potential and a little larger current in the glucose oxidation, and the peak current obtained was proportional to the electrode size and the glucose concentration. The oxidation peak was also affected by the supporting electrolyte, showing a positive shift in potential and a drop in current if a certain concentration of sodium hydroxide was not reached. The catalytic activity of the silver modified gold film electrodes was stable, and a certain power of electricity was obtained with a glucose–air fuel cell.     

表层稀土掺杂PbO_2电极及对苯酚电催化氧化性能研究

以钛电极为基体,用热分解法制备Sn-Sb中间层,电沉积方法制备稀土La掺杂PbO2电极,优化了制备改性PbO2电极的电沉积温度、电沉积时间及稀土掺杂量。以苯酚废水为目标有机物,借助于苯酚去除情况分析电极的电催化氧化能力;分析了电极结构与电催化特性之间的关系。采用SEM、EDX和XRD分析了制备电极的表面形貌、元素组成、晶体结构。实验结果表明:电沉积液温度50℃,电沉积2 h,稀土镧掺杂量4∶1的PbO2电极降解苯酚电催化性能有明显改善,其去除率达到90.9%。     

A new coral structure TiO2/Ti film electrode applied to photoelectrocatalytic degradation of Reactive Brilliant Red

A novel structure TiO₂/Ti film was prepared on a titanium matrix using anodic oxidation technique and applied to degrade Reactive Brilliant Red (RBR) dye in simulative textile effluents. The film was characterized by Field-Emission Scanning Electron Microscope (FE-SEM), Laser Micro-Raman Spectrometer (LMRS), UV–vis spectrophotometer (UVS) and Photoelectrocatalytic (PEC) experiment. The results show that the surface morphology of the film is coral structure, and the crystal structure of the film is anatase. The absorbency of the coral structure TiO₂/Ti film is 87–93% in the UV light region, and 77–87% in the visible light region. PEC experiment indicates that the photocurrent density of the coral structure TiO₂/Ti film electrode achieves 160 μA/cm². The color and Chemical Oxygen Demand (COD) removal efficiencies of RBR achieve 73% and 60% in 1 h, respectively. These are 16% and 58% higher than those of nanotube TiO₂/Ti film electrode. These were attributed to that these electrodes with different surface morphologies exhibit distinct surface areas and light absorption rate.     

Role of iron oxide impurities in electrocatalysis by multiwall carbon nanotubes: An investigation using a novel magnetically modified ITO electrodes

The role of iron oxide impurities in the electrocatalytic properties of multiwall carbon nanotubes (MWCNTs) prepared by catalytic chemical vapour decomposition method (CCVD) is studied in detail. A novel magnetically modified electrodes have been developed by which MWCNTs were immobilized on indium-tin oxide (ITO) electrodes, without any chemical binders. The electro-catalytic oxidation of dopamine, and reduction of hydrogen peroxide have been studied by cyclic voltammetry on magnetically modified electrodes with (i) MWCNTs with occluded iron oxide impurities (Fe-MWCNTs), (ii) MWCNTs grown on iron oxide nanoparticle particulate films (Io-MWCNTs) and (iii) pristine iron oxide nanoparticle particulate film (Io-NPs). A shift towards less positive potentials for the oxidation of dopamine was observed which is in the order of Fe-MWCNTs < Io-MWCNTs < Io-NPs. Similarly, trend towards less negative potentials for the reduction of hydrogen peroxide was observed. Thus, the electrocatalytic activities displayed by MWCNTs have been attributed to the iron oxide impurities associated with it. The systematic variation was related to the nature of interaction of iron oxide nanoparticles with MWCNT surface.