镍纳米线电极的电化学氧化还原行为及其对乙醇的电化学氧化催化作用

镍电极;电池;电催化;镍纳米线电极的电化学氧化还原行为及其对乙醇的电化学氧化催化作用     

氧化还原蛋白质在模拟生物膜修饰电极上的直接电化学

评述了氧化还原蛋白在模拟生物膜这种新型的化学修饰电极上的直接电化学研究的进展。对蛋白质在表面活性剂薄膜电极和多层复合薄膜电极上的电化学行为、模拟生物膜的超分子结构以及蛋白质在该类薄膜修饰电极上对不同底物的电催化性质进行了较详细的介绍。     

硫氰酸盐电化学氧化的动力学复杂性

本文利用多种电化学方法研究了多晶电极上硫氰酸盐电化学氧化的动力学和机理,观察到电流和电位振荡。循环伏安测量表明氧化动力学分为二步过程。除了振荡现象,系统也展示双稳态,利用时间电位扰动,氧化反应可在高电位和低电位稳态之间转换,而且强烈吸附的惰性离子也可诱导从振荡转化为稳态。     

二氧化硫的电化学氧化过程：Ⅱ.SO2在贵金属电极上的氧化机理

采用计时电位法、计时电流法和稳态极化曲线法研究了ＳＯ＿２在Ａｕ和Ｒｕ两种不同类型贵金属催化剂上的氧化过程，提出了ＳＯ＿２在这两类电极上的氧化机理。     

三维电极电化学反应器对有机废水的降解研究

本文提出一种基于三维电极电化学反应器处理有机废水的新技术 ,结果表明 :该反应器能有效地去除苯胺 ,但其去除率受外加电压、溶液中Fe2 +的浓度、pH值及处理时间 (t)的影响较大 .该项技术处理有机废水效果明显 ,主要是基于电致过氧化氢 ,在Fe2 +存在情况下迅速生成对有机物有很强氧化作用的羟基自由基 .通过ESR法测出了在该电化学反应器处理废水过程中产生的羟基自由基     

新型Ti/TiOxHy/Sb-SnO2电极上苯胺电化学氧化反应

苯胺是一种重要的化工原料,广泛应用于印染、制药、造纸、橡胶等领域.随着化工行业的迅速发展,苯胺的需求量越来越大.然而,苯胺毒性高,大量使用势必造成水体中苯胺浓度的升高,给人类健康及生态环境造成危害.因此,急需一种高效、洁净、经济的方法处理含苯胺废水.电化学氧化法比较新颖,相比传统废水处理方法,它具有高效、简单、清洁等优点,因此被应用于很多废水处理当中,但过多的能耗限制了其进一步广泛应用.阳极作为电化学氧化技术的核心部件,直接影响到电化学氧化反应性能.因此开发出一种高效、经济的阳极材料很有必要.此外,对苯胺降解条件的优化也同样重要.关于苯胺电化学氧化,已有的研究包括Pt电极、PbO2电极和石墨电极等阳极材料.比较而言, Ti/Sb-SnO2电极具有制备工艺简单,析氧过电位较高,材料廉价和电催化性能较强等优点.然而,它的稳定性仍有待提高.因此本文制备了一种高稳定性的Ti/TiOxHy/Sb-SnO2电极,并用于处理苯胺废水.较为系统地研究了电流密度、苯胺初始浓度、pH、NaCl投加量及反应器类型对苯胺电催化氧化性能的影响,同时采用扫描电镜(SEM)、X射线衍射(XRD)和电化学测试对该电极进行了表征,并应用紫外-可见光谱、化学需氧量、电流效率及能耗对不同参数进行评定和优化. SEM及XRD结果表明, Ti/TiOxHy/Sb-SnO2电极涂层覆盖比较完全、紧实,未出现裂缝的发生,因而有利于提高电极稳定性.循环伏安测试结果表明,此电极具备较高的析氧过电位(2.0 V vs Ag/AgCl)及电化学孔隙度(76.31%),因此有利于电极催化性能的提高.苯胺电化学氧化实验结果发现,该反应符合准一级动力学模型,且高电流密度、酸性环境、适当NaCl投加量(0.2 wt%)更有利于苯胺的降解.另外, Ti/TiOxHy/Sb-SnO2电极在三维反应器中对苯胺的处理效果要远远好于在二维反应器中.可以看出, Ti/TiOxHy/Sb-SnO2电极具有较好的处理苯胺性能,可为苯胺废水处理的应用提供了一定的理论指导.     

电化学氧化法去除苯酚研究

利用氯碱厂报废的DSA电极电解苯酚,结果显示:此电极对一定浓度的苯酚溶液有较好的去除效果.按影响电解效果各主要因素进行筛选,最佳实验条件为:电流密度30mA/cm2,pH10,支持电解质浓度10mg/L,苯酚浓度10mg/L.电解2h后,CODcr的去除率为66.7%,吸光度去除率为90%.     

硫代硫酸盐在铂电极上的电化学氧化行为

用循环伏安法测定了硫代硫酸盐在铂电极上的电化学氧化行为, 结果表明, 其电化学氧化行为与体系的pH和扫描速度密切相关. 当pH为5~6时, 硫代硫酸盐的循环伏安曲线出现三个氧化峰, 峰电位分别在0.05 V、0.58 V和1.02 V附近, 随pH值升高和扫描速度的降低, 0.05 V附近的氧化峰逐渐变得明显, 同时各氧化峰的峰电位与扫描速度的对数, 峰电流与扫描速度的平方根均成很好的线性关系；当pH为8~9时, 硫代硫酸盐的循环伏安曲线出现三个明显的氧化峰, 峰电位分别在0.05 V、0.91 V和1.22 V附近. 随扫描速度降低, 循环伏安曲线出现交叉, 体系呈现明显的电化学振荡行为；但当pH=10时, 1.22 V附近的氧化峰消失. 硫代硫酸盐的电化学氧化行为非常复杂, 电化学氧化机制随体系pH的变化而变化.     

苯酚的电化学氧化及测定

本文研究了在硼砂介质中，苯酚及其衍生物 的电化学行为，利用苯酚在－０．５Ｖ吸附富集，再进行氧化溶出，建立了测定苯酚的新方法。     

发泡镍电极电化学还原嘌呤中间体

由三维发泡镍电极H2SO4电解质和阳离子交换膜,组成隔膜式三维发泡镍电解循环装置.利用该装置将3-甲基-4-亚氨基-5-异亚硝基脲嗪(NAU)电还原为3-甲基-4,5-二氨基脲嗪(DAU).比较发泡镍阴极的电流密度,测定不同pH条件下的反应电位.结果表明,发泡镍电极的电流密度比平板镍高77.3%～86.7%,电流效率平均90.3%,NAU还原转化率平均98.4%,电还原能耗平均2.92kWh/kg.恒电流电还原过程出现峰电位,继续延长电还原时间则有副反应产生.分别以传统铁粉还原和电还原的DAU完成下游嘌呤产品的合成,证明电还原产品收率不低于铁粉还原.     

甲酸Pt电极电化学氧化体系中时间自组织导致的可利用功耗失

在电极化学反应步骤为控制步骤的条件下,对甲酸阳极氧化体系中出现的电化学振荡的阈值及跨越阈值后状态演化的极限环路径进行了系统动力学计算.同时,根据非平衡电极过程的耗散-涨落理论,进一步对跨越振荡阈值前后的临界区与电化学震荡区的极化曲线及功耗谱进行了随机热力学分析计算.研究结果表明,跨越临界区后单位电化学反应功耗谱出现突降...     

Simple System for Oxidation of Alcohols in Aqueous Solution

A simple and mild system for conversion of primary and secondary alcohols to corresponding aldehydes and ketones has been developed using aqueous sodium dichloroiodate at room temperature in water. This novel application of aqueous sodium dichloroiodate gives high yield and offers a number of advantages in terms of safety and ease of use in comparison to other methods that often employ toxic and hazardous solvents and materials.     

混合超级电容器AC/LiMn2O4体系的电化学性能

对AC/LiMnO4体系混合电容器进行研究,以活性炭(AC)为负极材料,尖晶石结构的LiMn2O4为正极材料,Li2SO4为电解液。该体系的原理与锂离子电池很相似,从本质上说属于一种特殊的锂离子电池。改变正负极的质量配比,根据其电化学性能确定了该体系最佳的正负极质量配比。对不同电解液浓度的电容器进行不同电流密度充放电测试,发现电解液浓度增加,会使容量和大电流性能得到明显改善,极化电阻的增大会大大降低放电电压平台。实验表明该体系具有较高的能量密度和功率密度,同时保持了良好的循环性能。     

铁卟啉修饰电极催化氧化测定儿茶酚类化合物

将铁卟啉氯化－５，１０，１５，２０－四－（－３－甲氧基－４－羟基苯基）卟啉铁（ＴＭＨＰＰ·ＦｅＣｌ）修饰在玻碳电极表面，制备成对儿茶酚类化合物具有高的响应的ＴＭＨＰＰ·ＦｅＣｌ修饰电极。该电极对多巴胺、肾上腺素等儿茶酚类化合物在各自的响应区间内有良好的线性关系，电极具有灵敏度高、响应快、稳定性好等特点。电极响应时间小于１０ｓ，儿茶酚类检测浓度在１０（－６）ｍｏｌ／Ｌ数量级。     

Oxidation of Tyrosine Photoinduced by Pterin in Aqueous Solution

Pterins, heterocyclic compounds widespread in biological systems, accumulate in the skin of patients suffering from vitiligo, a chronic depigmentation disorder. Pterins have been previously identified as good photosensitizers under UV‐A irradiation. In this work, we have investigated the ability of pterin (Ptr), the parent compound of oxidized pterins, to photosensitize the oxidation of tyrosine (Tyr) in aqueous solutions. Tyr is an important target in the study of the photodynamic effects of UV‐A radiation because it is oxidized by singlet oxygen (¹O₂) and plays a key role in polymerization and cross‐linking of proteins. Steady UV‐A irradiation of solutions containing Ptr and Tyr led to the consumption of Tyr and dissolved O₂, whereas the Ptr concentration remained unchanged. Concomitantly, hydrogen peroxide (H₂O₂) was produced. By combining different analytical techniques, we could establish that the mechanism of the photosensitized process involves an electron transfer from Tyr to the triplet excited state of Ptr. Mass spectrometry, chromatography and fluorescence were used to analyze the photoproducts. In particular, oxygenated and dimeric compounds were identified.     

Kinetics of Polyol Oxidation by Ozone in Aqueous Solutions

Spectrophotometry is applied to study the oxidation of ethylene glycol, triethylene glycol, glycerol, etriol, pentaerithritol and mannitol by ozone in aqueous solutions at 277–304 K. Rate constants and activation parameters of the reaction are measured. It is proposed that the oxidation of these alcohols by ozone occurs via the same mechanism. The formation of an intermediate complex is a rate-limiting step in the case of diols; the decomposition of the complex is a rate-limiting step for tri- to hexatomic alcohols.     

Modifying Electrode Properties of Carbon-Fiber Materials by Electrolysis in Aqueous Solutions

The possibility of applying electrolysis in aqueous solution for the modification of electrode properties of carbon-fiber materials (CFM) is examined. It is shown that the cathodic and anodic polarization of CFM in solutions of acids and alkalis alters the state of the surface of fibers that constitute CFM, which is manifested in a change of the CFM electrode potential. The possibility of changing the CFM electroconductivity by an electrode treatment is demonstrated. This makes it possible to design electrodes with electroconductivity that varies over the electrode's thickness. The latter is of importance for both developing non-isoelectroconducting three-dimensional electrodes with a rigid matrix and comprehending operation principles of carbon-fiber electrodes. The obtained experimental data conform to the calculated dependences, specifically, profiles of electroconductivity and polarization over the electrode thickness are similar.     

血红素修饰电极电催化氧化测定儿茶酚类化合物

采用循环伏安法将血红素修猸于玻碳电极表面，制备出对儿茶酚类化合物具有电催化氧化作用的血红素修饰电极（Ｈｅｍｅ／ＧＣ）。该电极上的催化氧化峰电流与邻苯二酚、多巴胺、肾上腺素等儿茶酚类化合物的浓度在各自响应的范围内有良好的线性关系，检测下限为４￣８×１０＾－８ｍｏｌ／Ｌ。用于多巴胺和肾上腺素药物针剂的测定结果令人满意，回收率９８￣１０２％。     

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.     

光电催化氧化甲醇电极

直接甲醇燃料电池 (DMFC)可直接利用甲醇 ,无须中间转化装置 ,具有系统结构简单、体积能量密度高、燃料补充方便等优点 .从提高电流密度和稳定催化剂本征活性这两方面来看 ,DMFC需要解决的关键问题是使甲醇直接氧化的阳极材料 .近年来有关此类阳极材料的制备与催化性能的研究报道日益增多 [1,2 ] ,但都是单纯地从光催化或电催化的角度出发 .本文提出一种利用 Ti O2 为光催化剂 ,Pt- Ru为电催化剂 ,试图将光催化与电催化反应发生于一体 ,使甲醇能得到联合的催化氧化作用 ;同时为了能进一步增加Ti O2 的光催化氧化能力 ,改变 Ti O2 - n…