浓碱溶液中铜阳极产物的阴极还原行为研究I: Cu(I)产物的阴极还原

采用特定的电势扫描程序测出了浓碱溶液中Cu(I)阳极产物的多重还原电流峰。根据各峰之间转化或竞争的关系, 提出了亚铜氧化物的吸附成相和溶解沉淀两种途径共存的形成机理。为确定各阴极峰的归属, 本文采用了将阴极电流峰与XRD和XPS特征峰进行半定量对比的方法。     

浓碱溶液中铜阳极产物的阴极还原行为研究 Ⅰ. Cu(Ⅰ)产物的阴极还原

采用特定的电势扫描程序测出了浓碱溶液中Cu(Ⅰ)阳极产物的多重还原电流峰.根据各峰之间转化或竞争的关系,提出了亚铜氧化物的吸附成相和溶解沉淀两种途径共存的形成机理.为确定各阴极峰的归属,本文采用了将阴极电流峰与XRD和XPS特征峰进行半定量对比的方法.     

浓碱溶液中铜阳极产物的阴极还原行为研究：Ⅱ,Cu（Ⅱ）产物的阴极还原

采用恒电热氧化－动电势或恒电流还原法研究了铜在浓碱深液中二次氧化产物的阴极还原 行为，共分辨分７个阴极电流峰或相应的多个阴极是民势平阶，对各阴极峰的归属进行了指认，并探讨了铜阳极二次氧化反应历程。     

硫化亚铁阴极的电极过程机理

应用循环伏安法研究了硫化亚铁阴极的电极过程机理 ,电极反应过程伴随着难溶硫化亚铁的形成与溶解 ,该电极过程受欧姆电阻控制 .根据循环伏安曲线峰电流和峰电位与扫描速度平方根成线性关系 ,提出了电极过程的欧姆电阻控制模型 ,导出峰电位和峰电流与扫描速度之间的关系式 ,理论分析与实验结果一致 .     

锂-硫化铜电池及其阴极行为的研究

本文研究了Li/CuS电池的一般放电行为,着重探讨了阴极放电反应,根据电池温度系数,X射线衍射试验,电池电动势与放电深度等试验数据,认为电池的阴极反应是锂在正极上进行电化学嵌入反应,从硫化铜阴极的循环伏安试来看,Li/CuS电池有可能成为二次电池.     

生物样品中砷的阴极溶出伏安法测定

提出了用阴极溶出伏安法测定生物样品中痕量砷 ;砷 (Ⅲ )在HCl-CuCl介质中产生一灵敏的溶出峰 ,峰电位位于 -0.804V ,砷含量在10×10 -9～500×10 -9(w)范围内与峰电流成正比 ;研究了酸度、CuCl浓度和起始电位对峰电流的影响 ;该法用于奶牛饲料和猪肾中砷的测定 ,分析结果令人满意     

SbO+离子的阴极还原

三价锑常用作锌粉置换法除去硫酸锌电解液中钻杂质的活化剂。在此过程中三价锑本身也被还原。置换反应本质上是一个电化学过程。因此,研究三价锑的阴极还原行为是有意义的。关于三价锑的阴极还原,Koval等研究了酒石酸盐溶液中Sb(Ⅲ)的电沉积。Tomlinson曾指出,在高电流密度下电解时,阴极上会析出锑化氢(SbH_3)。吴浩青等在研究酸性溶液中锑电极的电化学行为时,也曾指出了SbH_3的生成。本文采用旋转电极上的动电位扫描、旋转环盘电极以及交流阻抗技术研究硫酸钠溶液中SbO~+离子的阴极还原过程。     

储氢合金阴极电还原葡萄糖制备山犁醇

混合稀土储氢合金具有的吸氢性能,可以以氢化物的形式可逆吸放氢,并在适当的条件下以高活性原子氢的形式释放所储存的氢;经活化的混合稀土储氢合金表面偏析形成的富镍层具有良好的催化氢化能力。利用稀土系储氢合金RENi3.9Co0.59Mn0.28Al0.22为阴极,恒电流电解法还原葡萄糖制备山梨醇,采用正交设计法优选得出电解条件：阴极液为0.4mol/L葡萄糖溶液,40℃,pH＝12,电流密度为0.5A/dm^2。在该条件下取得了675的电流效率和80％的还原产率;探讨了储氢合金阴极对葡萄糖电化学还原反应机理。     

石墨-五氯化锑层间化合物在有机电介质溶液中的电化学行为和结构研究

通过测定循环伏安曲线研究了石墨-SbCl5在1MLiClO4-PC(碳酸丙二醇酯)溶液中的电化学行为.I.II级石墨-SbCl5的还原电流峰出现在2.75～2.35V,氧化电流峰在2.85～3.05V(相对于Li/Li[+]).III级和IV级的相应电位区间与上相同,但其峰值较小,且曲线较为平缓,III级石墨-SbCl5的方波恒电流充放电表明,在500μA/cm[2]下,Li的插入量x(x=Li/C36SbCl5)在0.3以内,电极具有良好的可逆性,根据库仑滴定数据,放电前后X射线衍射图谱与电镜衍射花样的变化,初步认为I.II混合级石墨-SbCl5放电时的阴极反应是锂插入和形成新的层间化合物LiC24SbCl5的两个过程。     

苯亚甲基丙二腈在汞阴极上的还原反应

本文应用了多种电化学方法(循环伏安法,微分脉冲极谱法等)及UV光谱,GC-MS手段研究了苯亚甲基丙二腈(BDMN)在汞阴极上的还原过程.在0.03mol.L^-1四乙基溴化铵(TEAB),50%二氧六环-水介质中BDMN还原的微分脉冲极谱图上有两个峰,第一个峰是此分子中的双键还原,生成苄基丙二腈引起的,峰电位在-0.98V(vs.SCE).第二个峰的峰电位在-1.55V(vs.SCE),此峰是BDMN的水解产物苯甲醛还原为苯甲醇产生的.BDMN的整个电极反应为ECEC过程.此处,对BDMN及二氧六环在汞电极上的吸附现象也进行了研究.     

Stripping voltammetric determination of traces of peptides and proteins containing disulphide linkages

Stripping voltammetry has been investigated for the determination of traces of ribonuclease, somatostatin, oxytocin, felypressin, insulin and oxidized glutathione at concentrations down to 1.5 × 10^?9 M. Repeated cyclic potential scans with an initial cathodic scan were used after accumulation at +0.1 to –0.3 V vs. Ag/AgCl at a hanging mercury drop electrode. In presence of excess of copper(II) ion, the first two compounds yield a well-defined peak couple at ?0.5 to ?0.6 V, with cathodic and anodic peaks of equal height, the accumulated product being adsorbed in both its oxidized and reduced state. Oxytocin and felypressin first yield two unresolved cathodic peaks, one of which disappears in the second scan cycle. Oxidized glutathione yields a large cathodic peak but a small anodic peak because of desorption in the reduced state. Excess of copper(II) is reduced during the accumulation, so that the electrode is actually copper amalgam. The peaks obtained with copper(II) present are considered to be due to redox reactions of copper complexes formed with the cysteine parts of the molecules. These peaks are suitable for quantitative purposes; calibration equations are given. Without copper(II), the substances show stripping responses of different complexity and magnitude. Insulin gives usable stripping peaks only without copper ions.     

Cyclic voltammetric studies on gallium film electrodes in alkaline media

Using cyclic voltammetric techniques the electrochemical behaviour of gallium in alkali media has been investigated. Three anodic peaks, one cathodic peak, and a secondary anodic peak—an observation hitherto unreported—are obtained. Detailed analyses of these various stages of oxidation and reduction based on their peak potential and peak current characteristics have revealed the nature of the underlying electrochemical reactions.     

Cyclic voltammetric studies of the redox behavior of iron(III)-vitamin B6 complex at carbon paste electrode

Electrochemical redox behavior of Fe-vit B₆ complex is investigated in HEPES buffer in the pH range 5.1–13.1 using cyclic voltammetry. Well-defined anodic and cathodic peaks are observed in the voltammograms at pH 13.1. At pH 8.0, only one cathodic peak and at pH 5.1, only one anodic peak are found. At all the pH values, the peak potential separation is much higher than that of a reversible electrochemical reaction. The peak current ratio (i _pa/i _pc) is less than unity and decreases with the scan rate. Published in Russian in Elektrokhimiya, 2006, Vol. 42, No. 6, pp. 691–697. The text was submitted by the authors in English.     

Electrochemical Study of Catechol in the Presence of Dibuthylamine and Diethylamine in Aqueous Media: Part 1. Electrochemical Investigation

Electrochemical oxidation of catechol has been studied in the presence of secondary amines as nucleophiles in aqueous solution with various pH values using cyclic voltammetry and differential pulse voltammetry. Cyclic voltammetry of catechol in pure buffered solution (2.00 pH<9.00) shows one anodic and corresponding cathodic peak which relates to the transformation of catechol to corresponding o‐benzoquinone and vice versa within a quasi‐reversible two electron transfer process. Also, a little amount of o‐benzoquinone undergoes polymerization reaction. Cyclic voltammogram of catechol in the presence of nucleophilic amines, show one anodic peak in the first scan of potential but on the reverse scan the corresponding cathodic peak disappear and new peak is observed at less positive potential. In the second scan of potential also a new anodic peak is observed. On the other hand at high concentration of amines the redox peak attributable to formed polymer disappear showing that in this condition the polymerization reaction occurs at non‐measurable extent. On the basis of these observations we propose an ECE mechanism for the electrochemical oxidation of catechol in the presence of secondary amines.     

2-羟基-1,4-萘醌的电化学氧化还原机理研究

利用现场红外光谱电化学方法、 红外光谱循环伏吸法(CVA)和导数循环伏吸法(DCVA)研究了2-羟基-1,4-萘醌(2-HNQ)在乙腈溶剂中的电子转移机理. 在扫描范围为0.2~-1.8 V时, 2-HNQ的循环伏安(CV)图中有2对氧化还原峰. 在扫描范围为1.0~-2.0 V时, CV图在更正的电位下会出现1个氧化峰. 通过分析循环伏安扫描过程中1656, 1495, 1549和1325 cm^-1等峰的变化, 观察到整个电化学过程中存在2种中间状态, 去质子化醌(Q-O^-)还原生成的自由基二价阴离子会继续发生电化学反应, 即Q-O^-的还原遵循电化学-电化学反应机理(EE机理). 红外分析结果表明, 2-HNQ的电化学过程中存在较强的氢键作用.     

ALSV investigation of the phase composition of electrolytic Cu + Sn alloys

Anodic linear sweep voltammograms (ALSVs) have been recorded for thin layers of Cu + Sn alloys electrochemically deposited on graphite from a pyrophosphate bath. Three characteristic peaks were found. The first peak, appearing in the ALSVs of all samples, could be ascribed both to pure Cu (in the deposit obtained at low cathodic polarization) and to the η-Cu₆Sn₅ phase, while one of the other two peaks appearing only in the samples obtained at low cathodic polarization should reflect the presence of the -Cu₃Sn phase. The other peak, appearing only in the samples obtained at high cathodic polarization, is likely to reflect the presence of the tin-rich β-solid solution. The phase composition, in terms of the content of different phases, was determined as a function of the thickness of the alloy as well as of the deposition potential.     

An insight into Faradaic phenomena in activated carbon investigated by means of the microelectrode technique

Cyclic voltammetry was performed on activated carbon particles in a microelectrode setup to investigate the behaviour of an activated carbon with oxygen functionalities. Quinoid type redox peaks were clearly seen in the potential region around −0.5 V vs. Hg/HgO. After polarization below −0.4 V, an anodic peak confirms previous studies using a pristine carbon, but in the present work much higher in intensity. In addition, a corresponding cathodic peak, not previously reported, was also found. The appearance of this pair of peaks in a functionalized carbon may be connected to reversible hydrogen adsorption together with Faradaic reactions involving oxygenated functional groups.     

聚苯胺颗粒电极的制备与其电化学行为

采用循环伏安法,以含苯胺(An)的硫酸溶液为电解质,采用循环伏安技术在Pt微盘电极上得到随机、不连续沉积的聚苯胺(PAn)微颗粒和PAn膜.实验结果表明:H2SO4浓度、苯胺浓度、电位扫描上限和扫速对电化学合成随机、不连续沉积的PAn微颗粒具有重要影响.不连续随机沉积的PAn微颗粒电极与PAn膜电极在锂离子(Li-ion)电池电解质溶液中的行为有明显差异,不连续随机沉积的PAn微颗粒电极可以清楚地得到氧化还原电流峰,而PAn膜电极无法形成清晰的氧化还原电流峰.采用较缓慢扫描速度更有利于形成良好"结晶"的不连续PAn颗粒电极,该种电极可以同时具有高比能量和可逆性能.     

Voltammetric determination of hydroquinone on a mechanically renewed graphite-epoxy electrode in developing photographic solutions

Effect of various components of developing photographic solutions on parameters of electro-oxidation-reduction peaks of hydroquinone in neutral and acid supporting solutions on a graphite-epoxy composite electrode with surface mechanically renewed directly in solution prior to each polarization cycle was studied. A procedure is suggested for voltammetric determination of the content of hydroquinone from the cathodic peak in a freshly prepared developing photographic solution and from the anodic peak in a solution allowed to stay upon preparation for 1 day and more.     

Cathodic Stripping Determination of Water in Organic Solvents

A cathodic stripping voltammetry (CSV) method has been developed to determine water content in organic solvents based on electrooxidation of a gold electrode in the presence of water to form gold oxides upon anodic polarizations. Following cathodic potential scan, a sharp reductive stripping peak of gold oxides is generated and the magnitude of the peak current is related to the water content in the organic solvents. The method has been applied for determination of water in four commonly used water miscible organic solvents, acetonitrile, tetrahydrofuran, acetone and glacial acetic acid, with limits of detection of 60, 10, 40 and 10 ppm, respectively.