甲醇在Pt-Sn/Pb电极上的氧化行为——Ⅰ.电极催化特性的研究

采用欠电位沉积法,以铅电极作基体制备了负载型Pt-Sn双金属催化电极。应用循环伏安法和电位阶跃法研究了各种因素对该电极的催化活性和稳定性的影响,并应用XPS和AES技术分析了该电极的表面物性。该电极对酸性介质中的甲醇氧化反应显示出高于Pt-Sn/Pt电极的催化活性和稳定性。     

盐酸伪麻黄碱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

盐酸伪麻黄碱;碳纳米管修饰电极;电催化氧化;电化学动力学     

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。     

甲醇在Pt-Sn/Pb电极上的氧化行为 Ⅱ.氧化反应动力学特征的研究

在甲醇燃料电池体系中,已确信甲醇会在铂电极上形成强吸附的中间物种:(1)这一吸附中间物种可与从水中得到的氧发生反应:(2)(3)为研究反应机理,采用过各种实验手段分析B_(ad(?))。本工作采用旋转园盘电极的电化学实验方法研究了甲醇氧化反应过程的中间物种,并求取反应过程的动力学参数以探讨氧化反应的机理,进而分析了双金属催化剂的作用机理。     

纳米金修饰玻碳电极对鸟嘌呤的催化氧化

采用电化学沉积法制备了纳米金修饰玻碳电极,并用循环伏安法和电化学阻抗法进行了表征,以此建立了一种直接测定鸟嘌呤的电分析方法。在磷酸盐缓冲溶液(pH 6.0)中,研究了鸟嘌呤在纳米金修饰电极上的电化学行为,实验结果表明,纳米金修饰电极可以增强鸟嘌呤在电极表面的吸附,并加快鸟嘌呤在电极表面的电子传输,使其电化学信号明显增大,检测灵敏度大大提高,该修饰电极对鸟嘌呤表现出良好的电催化性能。在优化实验条件下对鸟嘌呤进行测定,方法的线性范围为8.0×10-7~6.0×10-5mol/L,检出限为1.0×10-8mol/L,在鸟嘌呤浓度为1.0×10-5mol/L时测得RSD(n=10)为2.5%。     

一氧化氮在Nafion—钴席夫碱膜修饰电极上的电催化氧化及其测定

将一种杂环席夫碱N,N′－2,6－二乙酰吡啶缩双苯胺和Nafion修饰在铂电极上,然后与钴（Ⅱ）反应,得到Nafion－钴席夫碱膜修饰电极。实验结果表明,该修饰电极具有良好的机械、化学和电化学稳定性,对生物分子一氧化氮的电化学氧化有显著的催化作用。以1.5次微分线性扫描伏安法测定一氧化氮,当浓度在2.8×10     

苯在旋转圆盘电极上的氧化过程动力学

Ｃｌａｒｋ等［１］研究苯阳极氧化过程,认为二氧化铅是最合适的电极,苯是二级反应,苯在阳极上首先氧化为产物对苯二醌,产物可进一步氧化成马来酸,直至氧化成二氧化碳．但Ｉｔｏ［２］等研究表明苯阳极氧化还有一个并行反应：苯直接氧化为马来酸．Ｆｌｅｓｚａｒ和Ｐ...     

聚苯胺薄膜修饰电极对抗坏血酸的电催化氧化

本文表明聚苯胺(PAn)薄膜修饰电极对水溶液中的抗坏血酸(AH_2)在较宽的pH范围和较宽的浓度范围内均有良好的电催化氧化作用, 为EC平行催化过程。利用旋转圆盘电极(RDE)进行了催化过程动力学分析, 求出了催化反应动力学参数。在抗坏血酸浓度10~(-2)～10~(-6) mol·L~(-1)范围内, 催化峰电流与AH_2浓度均成良好的线性关系, 且PAn薄膜修饰电极具有很好的稳定性, 有应用分析抗坏血酸的意义。     

过渡金属酞菁配合物化学修饰电极的研究：Ⅳ对抗坏血酸的电催化氧化

用化学吸附法首次制备了FE(Ⅱ)、Co(Ⅱ)、Ni(Ⅱ)和Cu(Ⅱ)的3,3′,3′′,3′′′-四硝基酞菁配合物化学修饰电极(ML CME),用循环伏安法(CV)研究了它们对抗坏血酸(AH_2)的电催化氧化.与未修饰玻碳电极(GC)相比,AH_2在ML CME(GC基体)上的氧化峰电位(Epa)负移150mV左右,氧比峰电流(Ipa)明显增大.各ML CME对AH_2的电催化氧化活性均有很高的稳定性.AH_2在ML CME上的氧化峰电流和AH_2的浓度之间有着良好的线性关系.     

Electrocatalytic Oxidation of Dopamine at Sol‐Gel Carbon Composite Electrode Chemically Modified with Copper Hexacyanoferrate

An organic‐inorganic composite electrode was prepared by the sol‐gel method. For this purpose the carbon composite electrode (CCE) was modified with copper hexacyanoferrate (CuHCF). The CuHCF‐CCE was prepared by two methods. In one method CCE was prepared in one step and in another method the electrode was prepared in a two‐step process. The electrochemical behavior of the CuHCF modified electrode was studied by cyclic voltammetry; the modified electrode shows a pair of peaks with a surface‐confined characteristic in a 0.1 M phosphate buffer (pH 7) with K⁺ cation, as a supporting electrolyte. The CuHCF‐CCE showed electrocatalytic activity toward oxidation of Dopamine (DA). The kinetics of the catalytic reaction was investigated by using chronoamperometry. The average value of the rate constant for catalytic reaction and the diffusion coefficient were calculated. At a 0.85 V potential under hydrodynamic conditions (stirred solution), the oxidation current is proportional to the dopamine concentration, and the calibration plot was linear over the concentration range of 5‐85 μM.     

Electrocatalytic Characteristics of Hydrazine and Hydroxylamine Oxidation at Coumestan Modified Carbon Paste Electrode

A coumestan derivative modified carbon paste electrode (CMCPE) was used as a sensitive electrochemical sensor for determination of electrocatalytic of hydrazine and hydroxylamine. The mechanism of electrocatalytic oxidation of both hydrazine and hydroxylamine using CMCPE was investigated by cyclic voltammetry and polarization studies. The kinetic parameters such as the electron transfer coefficient, α, heterogeneous rate constant, k′, and exchange current density, j₀, for oxidation of hydrazine and hydroxylamine at the CMCPE surface were determined using cyclic voltammetry. Further more, the linear dynamic range, sensitivity and limit of detection for hydrazine and hydroxylamine detections were evaluated using differential pulse voltammetry.     

Electrocatalytic Oxidation of Sulfite on a Cobalt Pentacyanonitrosylferrate Film Modified Glassy Carbon Electrode

The electrocatalytic oxidation of sulfite has been studied on the cobalt pentacyanonitrosylferrate modified glassy carbon electrode (CoPCNF). The CoPCNF films on the glassy carbon electrodes show an excellent electrocatalytic activity toward the oxidation of sulfite in 0.5 M KNO₃. The kinetics of the catalytic reaction was investigated by using cyclic voltammetry, rotating disk electrode (RDE) voltammetry and chronoamperometry. The average value of the rate constant, K, for the catalytic reaction and the diffusion coefficient, D, were evaluated by different approaches for sulfite and found to be 2.9×10² M^?1s^?1 and 4.6×10^?6 cm²s^?1, respectively. At a fixed potential under hydrodynamic conditions (stirred solutions), the oxidation current is proportional to the sulfite concentration and the calibration plot was linear over the concentration range 5×10^?6–1×10^?4 M. The detection limit of the method is 3×10^?6 M., low enough for the trace sulfite determination.     

石墨烯修饰玻碳电极对多巴胺的电催化氧化

通过3-巯丙基三乙氧基硅烷(METMS)将氧化石墨烯(GO)固载到玻碳电极(GCE)表面, 用电化学方法还原GO制备石墨烯修饰玻碳电极(rGO-METMS-GCE). 利用傅里叶变换红外光谱(FTIR)、 拉曼光谱(Raman)、 扫描电子显微镜(SEM)和原子力显微镜(AFM)等技术对GO和rGO-METMS-GCE的结构和表面形貌进行表征. 采用循环伏安(CV)和差分脉冲溶出伏安(DPV)法研究了rGO-METMS-GCE对多巴胺(DA)的电催化氧化性能及反应机理. 结果表明, 与裸GCE相比, DA在rGO-METMS-GCE电极上的氧化还原峰电流(i_pa和i_pc) 增大4倍, 氧化峰电位负移106 mV, 氧化峰与还原峰电位差(ΔE_p)从202 mV降低至66 mV, DA电化学氧化可逆性明显改善, 表明rGO-METMS-GCE对DA电化学氧化具有显著电催化作用. DA在rGO-METMS-GCE上的反应机理为单电子转移过程.     

苯二酚在聚吡咯膜修饰电极上的催化反应

儿茶酚等有机化合物是人体内的电活性物质，直接参予人体内的各种生理过程．有关这类物质的电化学行为一直是生物化学和化学领域的重要研究课题之一．但这些物质在固体电极上的电极反应迟缓，过电位高，检测比较困难．利用化学修饰电极可以对这类物质的电极反应进行催化，可制成各种电流式传感器[1]，特别是聚合物膜修饰电极传感器有催化效率高、稳定性好等优点问，是目前电化学传感器研究中的一个主要方面．聚毗咯膜（PPy）修饰电极自从出现以来已得到了广泛的应用，在电分析化学领域更具有稳定性好，制备条件简便等优点．一些在固体电极…     

Electrocatalytic Oxidation and Determination of Sulfite with a Novel Copper‐Cobalt Hexacyanoferrate Modified Carbon Paste Electrode

The electrocatalytic oxidation of sulfite has been studied at a stable electroactive thin film of copper‐cobalt hexacyanoferrate (CuCoHCF) hybrid electrodeposited on a carbon paste electrode (ECMCPE). A linear range of 5 μM to 5 mM of sulfite, with an experimental detection limit of 1 μM, was obtained using the cyclic voltammetric method. The oxidation of sulfite showed no significant fouling effect on the modified electrode surface at sulfite concentrations below 5 mM. The proposed modified electrode exhibited several attractive features, including simple preparation, fast response, good stability and repeatability, and could be applied to sulfite determination in real samples.     

Electrocatalytic Oxidation of Methanol on a Nickel‐Porphyrin IX Complex Modified Glassy Carbon Electrode in Alkaline Medium

Electrocatalytic oxidation of methanol on a glassy carbon disc electrode modified with Ni(II)‐hematoporphyrin IX, complex and conditioned by potential recycling in a limited range (between 100 and 600 mV vs. SCE) in 0.10 M NaOH solution, abbreviated as NiOHPME(A), was studied by cyclic voltammetry in alkaline medium. The results were compared with those obtained for a NiO modified glassy carbon electrode, NiOME, prepared in similar conditions. The findings show that the NiOHP film at NiOHPME(A) behaves as an efficient electrocatalyst for the oxidation of methanol in alkaline medium via Ni(III) species with the cross‐exchange reaction occurring throughout the layer at a low concentration of methanol and for a thin film of modifier. A plausible mechanism was proposed for catalytic oxidation of methanol at NiOHP modified electrode. Moreover, the effects of various parameters such as the scan rate, methanol concentration, thickness of NiOHP film and the real surface area of modified electrode on the oxidation of methanol were investigated. Finally, it has been shown that the NiOHPME(A) has a long‐term stability toward the oxidation of methanol.     

Al Electrode Modified by Au Atoms as a Novel Electrode for Electrocatalytic Oxidation of Thiosulfate

An aluminum electrode modified with gold atoms was introduced as a novel electrode. Gold atoms were deposited both chemically and electrochemically onto the aluminum electrode to make an aluminum/gold (Al/Au) modified electrode (ME). The experimental results showed that the Al/Au modified electrode prepared by chemical deposition, exhibits much more current than the electrochemical deposition method. The electrochemical behavior of the Al/Au modified electrode was studied by cyclic voltammometry. This modified electrode showed two pairs of peaks, a₁c₁ and a₂c₂, with surface‐confined characteristics in a 0.5 M phosphate buffer. The dependence of E_pa of the second peak (a₂c₂) on pH shows a Nernestian behavior with a slope of 55 mV per unit pH. The effect of different supporting electrolytes, solution's pH and different scan rates on electrochemical behavior of Al/Au modified electrode was studied. Au deposited electrochemically on a Pt electrode (Pt/Au) was also used as another modified electrode. A comparative study of electrochemical behavior of bare Al, Pt/Au and Al/Au modified electrodes showed that both Pt/Au and Al/Au electrodes have the ability of electrocatalytic oxidation of S₂O₃^2?, but the electrocatalytic oxidation on the latter was better than the former. The kinetics of the catalytic reaction was investigated by using cyclic voltammetry and chronoamperometry techniques. The average value of the rate constant for the catalytic reaction and the diffusion coefficient were evaluated by means of chronoamperometry technique.     

Electrocatalytic Oxidation of Estrogenic Phenolic Compounds at a Nickel‐Modified Glassy Carbon Electrode

This paper demonstrates for the first time, successful electrocatalytic oxidation of electroactive estrogenic phenolic compounds (EPCs) at a nickel‐modified glassy carbon electrode (Ni‐GCE). The electrode was evaluated in terms of electrocatalytic activity, sensitivity, linear dynamic range, limit of detection, and response stability. In comparison to bare glassy carbon electrode, current amplification was observed for EPCs at Ni‐GCE, for example, for a 40 µM estrone at Ni‐GCE was amplified by a factor of 1224. The Ni‐GCE gave good figures of merit with no evidence of electrode fouling. As an example, the limit of detection (S/N=3) for 17β‐estradiol was 100 nM and the response precision (n=5) was 3.4 %.     

CO在铂修饰的氧化钛电极上电催化氧化行为的研究

通过阴极还原-阳极氧化法制备了Pt—TiO2／Ti电极,研究了CO在该电极上的电化学行为和电极制备条件对CO电催化氧化的影响．结果表明,与Pt电极相比．CO在Pt—TiO2／Ti电极上的氧化峰峰电位负移了100mV,并且表现出较好的稳定性．通过XPS技术对Pt—TiO2／Ti电极进行了表征．发现Pt以金属形式存在,Ti以TiO2形式存在．Pt—TiO2／Ti电极能抗CO中毒的原因可能是因为TiO2的掺杂使引起催化剂中毒的桥式吸附的CO物种在复合催化剂上的吸附率较低所致．