Preparation of glass carbon electrode modified with nanocrystalline nickel-decorated carbon nanotubes and electrocatalytic oxidation of methanol in alkaline solution

Nanocrystalline nickel with an average diameter of about 16 nm and a face-centered cubic (fcc) structure was uniformly attached to the surface of carbon nanotubes (CNT) by wet chemistry. The sample was characterized by X-ray powder diffraction and transmission electron microscopy (TEM). A glass carbon electrode modified with nickel-modified multi-wall carbon nanotubes (MWCNTs-Ni/GCE) was prepared. The electrochemical behavior of the MWCNTs-Ni/GCE and the electrocatalytic oxidation of methanol at the MWCNTs-Ni/GCE were investigated by cyclic voltammetry in 1.0 mol/L NaOH solution. The cyclic voltammograms showed that the electron transfer between β-Ni(OH)₂ and β-NiOOH is mainly a diffusion-controlled quasireversible process, and that the electrode has high catalytic activity for the electrooxidation of methanol in alkaline medium, revealing its potential application in alkaline rechargeable batteries and fuel cells. __________ Translated from Chinese Journal of Applied Chemistry, 2007, 24(5): 503–506 [译自: 应用化学]     

氢氧化镍薄膜修饰玻碳电极的制备及其对L-赖氨酸氧化的电催化活性

采用恒电位沉积方法将氢氧化镍沉积到玻碳电极表面,得到稳定性高、催化活性好的氢氧化镍薄膜修饰玻碳电极;分析了影响薄膜形成过程的关键因素,确定了最佳薄膜制备方案;与此同时,将薄膜修饰玻碳电极用于生物样品L-赖氨酸的氧化测定,并探讨了其催化作用机理.结果表明,所制备的氢氧化镍薄膜修饰玻碳电极表面发生电化学反应[Ni(OH)2→NiOOH],从而促进电极表面的电子转移,实现对L-赖氨酸的电催化作用.当L-赖氨酸的浓度在1.0×10-4～4.0×10-7 mol/L范围内时,相应氧化峰电流与浓度呈线性关系,检出限达4.0×10-7 mol/L;据此可方便地制备稳定性好且灵敏度高的电流型传感器.     

Application of multi-walled carbon nanotubes modified carbon ionic liquid electrode for electrocatalytic oxidation of dopamine

A simple, sensitive, and reliable method based on a multi-walled carbon nanotubes (MWNTs) modified carbon ionic liquid electrode (CILE) has been successfully developed for determination of dopamine (DA) in the presence of ascorbic acid (AA). The acid-treated MWNTs with carboxylic acid functional groups could promote the electron-transfer reaction of DA and inhibit the voltammetric response of AA. Due to the good performance of the ionic liquid, the electrochemical response of DA on the MWNTs/CILE was better than that of other MWNTs modified electrodes. Under the optimum conditions a linear calibration plot was obtained in the range 5.0×10(-8) to 2.0×10(-4) mol L(-1) and the detection limit was 1.0×10(-8) mol L(-1).     

百里香酚在聚甲苯胺蓝/多壁碳纳米管修饰电极上的电催化氧化动力学研究

采用电聚合、滴涂及多层修饰方法制备了4种修饰电极,百里香酚在几种修饰电极上均是不可逆电氧化反应,其中聚甲苯胺蓝/多壁碳纳米管修饰电极的电催化效果最佳,过电位降低了111mV,氧化峰电流增大了5倍。在pH为7.69的PBS溶液中,百里香酚在聚甲苯胺蓝/多壁碳纳米管修饰电极上是电子转移数和质子数均为1的扩散控制不可逆电氧化过程,扩散系数D=4.8470×10-4cm2/s,电极有效面积A=0.0383cm2。氧化峰电流ip与浓度c在9.0×10-6～5.0×10-4mol/L范围内呈良好的线性关系:ip(A)=-3.781×10-5-0.0491c(mol/L),相关系数R=-0.9958,样品测定回收率为96.88%～101.50%。     

Novel nano-zeolite modified carbon paste electrode for electrocatalytic oxidation of methanol

Abstract  

Methanol is used as a fuel in the direct methanol fuel cell. Direct oxidation of methanol encounters large overvoltages at most unmodified electrode surfaces. The development of new procedures for electrocatalytic oxidation of methanol to decrease this overvoltage is therefore very desirable. In this paper, we report a new zeolite-modified carbon paste electrode based on Ni-ZSM-5 for methanol electrooxidation. Nanocrystallites of ZSM-5 (Si/Al of 50) with average particle size of 58 nm were synthesized using clear solutions at low temperature (90 °C) under atmospheric pressure. Ni(II) ions were incorporated into the zeolite by immersion of the modified carbon paste electrode with synthesized zeolite in a 1.0 M nickel chloride solution. Cyclic voltammetry showed that by using nano-sized zeolite, the oxidation current increased compared with that of micron-sized zeolite crystallites.     

修饰的多壁碳纳米管糊电极用于生物与制药样品中苄丙酮香豆素电催化氧化和测定

采用一种简单灵敏的方法开发了在多壁碳纳米管修饰的ZnCrFeO4糊电极(MWCNTs/ZnCrFeO4/CPE)表面测定苄丙酮香豆素的新型传感器.运用循环伏安法、差示脉冲伏安法、计时电流法和电化学阻抗谱考察了该化学修饰电极上苄丙酮香豆素的电化学性能.结果表明,MWCNTs/ZnCrFeO4/CPE电极对苄丙酮香豆素氧化表现出较高的电催化活性,在pH=4时,产生峰值氧化电流约0.97 vs Ag/AgCl参比电极.当苄丙酮香豆素浓度在0.02-920.0 μmol/L范围内,该峰电流与其呈线性关系,检测极限(3σ)为0.003 μmol/L.另外,运用差示脉冲伏安法测定了MWCNTs/ZnCrFeO/CPE电极上苄丙酮香豆素的催化反应速率常数和扩散系数.     

聚邻苯二胺修饰玻碳电极的制备及电催化性能

在磷酸盐缓冲溶液中研究了邻苯二胺在玻碳电极表面的聚合过程,探讨了各氧化还原峰的变化机理,用扫描电镜表征了聚邻苯二胺膜的形态结构。发现制备的聚邻苯二胺膜修饰电极对H2O2有显著的电催化还原特性,线性回归方程为:Δipa(μA)=-1.63 1.07cH2O2(mmol.L-1)(R=0.9947,n=19),线性范围为:5.89×10-2mmol.L-1~44.4 mmol.L-1,检出限为:0.02 mmol.L-1(3S/k),这对与产生H2O2的氧化酶相结合制备出响应各种底物的电化学生物传感器非常重要。考察了制备条件对膜电极电催化还原活性的影响,发现只有在弱酸条件下制备的膜电极才有较高的电催化活性。探讨了影响膜电极电催化还原灵敏度的因素,并考察了膜电极的稳定性。     

磺胺在碳纳米管修饰玻碳电极上的电化学行为

磺胺类抗菌药是一类允许在饲料中添加的兽用广谱抗菌药.它被广泛用于治疗家畜呼吸道、消化道细菌感染、猪萎缩性鼻炎、禽霍乱、伤寒等疾病[1].停药期用药或用药不当将导致动物食品中抗菌药残留超标.人们长期食用含磺胺类抗菌药残留超标的动物产品,将导致肝肾损伤和体内耐药菌株产生,危害到人们的身体健康和疾病治疗.     

苦参碱在多壁碳纳米管修饰玻碳电极上的电催化氧化及其电分析方法

研究了苦参碱(Matrine, MT) 在多壁碳纳米管修饰玻碳电极(MWCNT/GCE)上的电化学行为. 与GCE相比, MT在MWCNT/GCE上峰电位负移120 mV, 峰电流增大约2.5倍, 表明MWCNT/GCE对MT的电化学氧化具有良好的催化作用. 同时测定并计算了MT在MWCNT/GCE上的电极过程动力学参数: 电子转移系数α、电极反应速率常数ks、扩散系数D. 运用差分脉冲伏安法对苦参碱样品含量进行测定, 相对标准偏差为0.12%～2.9%, 加标回收率为98.4%～99.0%. 该方法可用于MT的电化学定量测定.     

二苯氨基碳酰肼在多壁碳纳米管修饰电极上的电催化氧化及电化学动力学研究

肼及其衍生物被广泛应用于医药,农药,水处理,军事,航天,光稳定剂以及化工生产助剂等诸多领域。因此对肼及其衍生物的研究有着极其重要的意义。二苯氨基碳酰肼(二苯氨基脲,又名二苯卡巴肼,D iphenyl Carbazide,DPC)广泛用于重金属离子的检测分析[1-4]。但是,目前关于DPC的电化学     

Electrochemical and electrocatalytic behaviors of poly(ferrocenylsilane)/DNA modified glass carbon electrode

Poly(ferrocenylsilane) (PFS), composed of electroactive ferrocene units existing in the polymer main chain, was directly dropped on the DNA modified glassy carbon electrode (GCE). The electrochemical and electrocatalytic behaviors of PFS/DNA/GCE were investigated in detail. Cyclic voltammograms of the PFS/DNA/GCE showed two pairs of reversible redox peaks, indicating a stepwise oxidation of the electroactive units. It was found that DNA film played a key role in immobilizing the PFS and facilitating the electron transfer between electroactive units of PFS and the GCE surface. Moreover, the PFS/DNA/GCE showed a good electrocatalytic ability to the oxidization of ascorbic acid (AA), suggesting it had the potential application as a new type of sensor to detect AA.     

芦丁修饰电极的电化学特性及其催化性能

研究了芦丁修饰玻碳电极的制备及其电化学性质,探讨了电极反应的机理为ECE过程。研究了它对抗坏血酸和KMnO4的电催化作用:在pH6.0的磷酸盐缓冲溶液(PBS)中,此修饰电极对抗坏血酸有良好的催化氧化作用,而对KMnO4有良好的催化还原作用。     

苯甲酰肼在多壁碳纳米管修饰玻碳电极上的电催化氧化及其电化学动力学性质

研究了苯甲酰肼(BH)在MWCNT/GCE上的电化学行为。实验结果表明,BH在GCE上的直接电化学氧化十分迟缓,无氧化峰出现,但在MWCNT/GCE上BH在0.20 V处出现了一个不可逆氧化峰,且峰电流大幅度增大,表明MWCNT/GCE对BH电化学氧化具有良好的催化作用。同时用计时库仑法(Chro-nocoulometry,CC)和计时电流法(Chronoamperometry,CA)测定了电极过程动力学参数:扩散系数D=8.73×10-5cm2.s-1,电子转移系数α=0.85,电极反应速率常数kf=1.45×10-3s-1。稳态电流-时间实验结果表明,电流响应信号随其浓度成比例增长,响应时间小于6 s,最低响应浓度为1×10-6mol/L。该方法可用于BH电化学定量测定。     

Voltammetric oxidation and determination of cinnarizine at glassy carbon electrode modified with multi-walled carbon nanotubes

We discovered a novel method to prepare a protein-based hydrogel, that is, a “Three-Dimensional Nanostructured Protein Hydrogel (3D NPH)”, which is composed of protein–polymer hybrid nanoparticles. In this study, we propose a novel protein microarray whose 3D NPH spots were prepared by dispensing a small volume of the solution of protein–polymer mixture on a substrate. The dispensed solution had a short time for cross-linking before its drying-up and the resulting 3D NPH had loosely cross-linked, thin spongy structure. Therefore, the reaction ratio between ligands and analytes was drastically improved in this system compared with the large volume system for Surface Plasmon Resonance (SPR) protein microarray.     

Electrochemical properties and electro-aggregation of silver carbonate sol on polycrystalline platinum electrode and its electrocatalytic activity towards glyphosate oxidation

This communication shows that colloidal suspensions of silver carbonate behave in a way which is new in voltammetric experience. Electrochemical signals typical of nucleation processes were observed during the electro-aggregation of silver carbonate on a platinum electrode. Modified electrodes, obtained by means of electro-aggregation of silver carbonate particles, showed catalytic activity towards the electrochemical oxidation of glyphosate, avoiding in this way typical passivation processes.     

Sensitive voltammetric determination of paracetamol by poly (4-vinylpyridine)/multiwalled carbon nanotubes modified glassy carbon electrode

A novel glassy carbon electrode (GCE) modified with a composite film of poly (4-vinylpyridine) (P4VP) and multiwalled carbon nanotubes (P4VP/MWCNT GCE) was used for the voltammetric determination of paracetamol (PCT). This novel electrode displayed a combined effect of P4VP and MWCNT on the electro-oxidation of PCT in a solution of phosphate buffer at pH 7. Hence, conducting properties of P4VP along with the remarkable physical properties of MWCNTs might have combined effects in enhancing the kinetics of PCT oxidation. The P4VP/MWCNT GCE has also demonstrated excellent electrochemical activity toward PCT oxidation compared to that with bare GCE and MWCNT GCE. The anodic peak currents of PCT on the P4VP/MWCNT GCE were about 300 fold higher than that of the non-modified electrodes. By applying differential pulse voltammetry technique under optimized experimental conditions, a good linear ratio of oxidation peak currents and concentrations of PCT over the range of 0.02–450 μM with a limit of detection of 1.69 nM were achieved. This novel electrode was stable for more than 60 days and reproducible responses were obtained at 99% of the initial current of PCT without any influence of physiologically common interferences such as ascorbic acid and uric acid. The application of this electrode to determine PCT in tablets and urine samples was proposed.     

Reduced graphene sheets modified glassy carbon electrode for electrocatalytic oxidation of hydrazine in alkaline media

This paper describes the electrochemical properties of reduced graphene sheets (RGSs) for the electrocatalytic properties towards the hydrazine oxidation in alkaline media. The RGSs have been produced in high yield by a soft chemistry route involving graphite oxidation, ultrasonic exfoliation, and chemical reduction. The RGSs possess excellent electrocatalytic activity towards the hydrazine oxidation. In our opinion, RGSs are a potential electrode material for direct hydrazine fuel cells and electrochemical sensors for hydrazine detection.