微圆盘电极上耦合一级均相反应的稳态电流

在电极表面反应物浓度均匀的近似假设下, 得到了微圆盘电极上暂态可逆反应的一般解. 然后利用该一般解得到了微圆盘电极上耦合一级均相反应的可逆电极反应CE、EC、EC′和ECE 的稳态电流计算公式.     

气体电极反应动力学的薄膜旋转圆盘电极方法研究

薄膜旋转圆盘电极方法是一种常用的评价气体物质在纳米电催化剂上的反应活性的方法,但是在数据分析过程中经常忽视了气体反应物在催化剂层中到活性位点的传质可能对估算的反应动力学参数的影响.本文以氧电极反应为例,使用薄膜旋转圆盘电极研究了不同担载量Pt/C电极的氧还原活性.实验结果表明,根据Koutecky-Levich方程求算相同电位下的"表观动力学电流密度"(对Pt活性面积归一化的mA/cm2Pt)或比质量电流(mA/μg Pt)随Pt担载量的减小而增大,说明在估算动力学电流时不能忽略O2在催化剂层中的扩散传质,而气体在催化剂层中的传质与催化剂层的结构、厚度、纳米催化剂的分散度等密切相关.建议在使用薄膜旋转圆盘电极方法来研究纳米催化剂气体电极反应活性时,首先系统考察担载量、分散度与催化剂层厚的影响,然后根据不同担载量催化剂归一化后的动力学电流密度(或比质量电流)-电势曲线是否重合来验证得到的是否是真实的动力学电流,从而得到更为准确的评价结果.     

非均相电解Mn^2＋的电极过程动力学研究

选择Ｐｂ－Ｓｂ－Ａｓ合金为研究电极，通过阳极极化曲线确定了非均相电解氧化Ｍｎ６２＋电极过程机理，即为在阳极上存在液相和固相两个反应；并确定了４０％Ｈ２ＳＯ４介质中Ｍｎ／Ｍｎ体系的条件电极电势为０．８８６Ｖ。采用旋转圆盘电极研究得到在非均相电解ＭｎＳＯ４过程中电极过程控制步骤为电荷传递－浓度极化混合控制步骤，并确定了电极反应的动力学参数。     

利用K-L方程估算旋转圆盘电极体系反应动力学电流的误差来源分析

旋转圆盘电极（RDE）体系主要用于低溶解度反应物的电极过程动力学研究. 在利用RDE技术研究不可逆电极反应动力学时,人们常利用Koutecky-Levich方程排除传质的影响,从总电流估算反应的动力学电流. 由于K-L方程是建立在系统满足稳态扩散模型的基础上,实际运用时如果体系偏离稳态扩散,就有可能对估算的动力学参数造成很大误差. 本文以氧气在多晶铂电极上的还原反应为例系统地估算了不同氧气浓度与电极转速下的误差,结果表明低氧气浓度与低圆盘转速的情况不满足稳态扩散条件,若此时仍根据K-L方程利用外推法进行分析,误差可达30%. 因此作者建议,在RDE体系中利用K-L方程估算动力学参数时,最好忽略低浓度与低转速下的数据,直接使用较高浓度与较高转速下的数据进行计算与分析.     

化学修饰电极的研究XVIII,四苯基钴卟啉化学修饰玻碳电极的热处理及其对氧的催化还原

本文研究四苯基钴卟啉化学修饰玻碳电极的热处理,经热处理的这种电极[(PCo/GC)h]具有对氧催化还原的异常高的稳定性和活性.在纯O2饱和的0.05mol.L^-^1H2SO4溶液中经循环伏安(CV)扫描3000次(100mV/s),其催化活性未见明显降低.研究了热处理温度(500-1000℃)对(PCo/GC)h电极电催化性能的影响.用紫外可见光谱对热处理产物的结构进行了分析.用CV法及旋转圆盘电极研究了O2在(PCo/GC)h电极上电催化反应动力学,测定了速率常数.在该电极上O2的还原反应为二电子还原成H2O2的不可逆过程.     

微圆盘电极技术测定表面化学微加工时的约束刻蚀剂浓度分布

利用微圆盘电极技术, 测定了KBr、L-胱氨酸和硫酸组成的刻蚀溶液体系中Pt电极表面电化学氧化产生的刻蚀剂Br2浓度分布, 为约束刻蚀剂层技术(CELT)中刻蚀体系的选择和优化提供更直观的依据. GaAs表面CELT微加工实验证明了用微圆盘电极测得的表面刻蚀剂的浓度分布趋势与微加工实验所得到的结果一致     

微电极对多步电极反应(EE反应)稳态过程的研究

本文推导了微盘及微球电极上EE反应的一般稳态电流表达式; 对ErEr,EqEr, EiEr, ErEq, ErEi, EiEi及EqEq各反应机理进行了详细讨论; 并以亚硫酰氯的还原反应为特例进行了研究及动力学常数的测定。     

卟啉化合物的电催化行为IV.载在石墨上经热处理的四(对甲氧基苯基)卟啉钴对胱氨酸还原的电催化作用

应用循环伏安法及带环的旋转圆盘电极(RRDE)在2mol.dm^-^3HCl溶液中研究了经热处理的四(对甲氧基苯基)卟啉钴(Co-TMPP)对胱氨酸还原反应的电催化作用.在循环伏安曲线上出现明显的氧化还原电流峰,表明Co-TMPP对胱氨酸还原有很好的电催化活性.在Co-TMPP/石墨电极上的还原反应为不可逆的简单电荷传递反应,其控制步骤的电子数为1.在极化电位较正时(-0.35~-0.45V)为电化学控制,在电位较负时(<-0.45V)为电化学及扩散混合控制.根据实验结果计算了动力学参数并初步讨论了反应机理.应用薄层盘环电极及聚四氟己烯粘结膜电极分别测定了胱氨酸还原反应的电流效率.实验结果表明,经热处理的Co-TMPP能提高胱氨酸还原反应的电流效率.     

2，3—二氨基吩嗪的薄层光谱电化学研究

研究了2，3—二氨基吩嗪(DAP)在金圆盘电极、金超微电极上的循环伏安行为 和在金网栅电极上的薄层循环伏安行为．在pH2．0的B—R缓冲溶液中的2，3—二氨 基吩嗪在金圆盘电极上为准可逆氧还过程；以超微电极法求得了2，3—二氨基吩嗪 在pH2．0的B—R缓冲溶液中的扩散系数，由耗竭性库仑电解和循环伏安法求得其电 极反应电子转移数和H+反应级数均为2，实验说明参与电极反应的H+也为2，并用循 环伏安法求得其标准电极反应速率常数．采用紫外—可见薄层光谱电化学方法测得 2，3—二氨基吩嗪的克式量电位和电子转移数，与电化学实验结果一致；双电位阶 跃—计时吸收紫外—可见薄层光谱电化学实验说明，2，3—二氨基吩嗪电还原无随 后化学反应，其在电极上经历了H+eH+e的两步一电子过程，生成产物2，3—二氨基 -5，10-二氢吩嗪．     

氢钼青铜对铂催化氧还原反应的促进作用

采用循环伏安法在玻碳电极上和硫酸溶液中电沉积制备出铂催化剂(Pt)及铂-氢钼青铜复合催化剂(Pt-HxMoO3), 用旋转圆盘电极研究并比较了它们对硫酸溶液中氧还原反应的催化活性. 研究结果表明, HxMoO3能明显地提高Pt对氧还原反应的电催化活性. 通过对静态电极上氧还原的峰电流与扫描速度的关系以及旋转圆盘电极上氧还原电流与旋转速度的关系的分析发现, HxMoO3提高了铂电极氧还原反应电荷传递步骤的传递系数, 因此加快了氧还原的动力学过程.     

氢电极反应绝对电极电位的表达式

本文将量子电化学热活化理论的氢电极反应的电子传递条件式在紧密双电层中展开,得到该电极反应的绝对电极电位表达式。     

Polyaniline‐Modified Silver and Binary Silver‐Cobalt Catalysts for Oxygen Reduction Reaction

Novel dendrite‐like silver particles were electrodeposited on Ti substrates from a supporting electrolyte‐free 30 mmol L^?1 Ag(NH₃)₂⁺ solution, to synthesize the den‐Ag/Ti electrode. Binary Ag_xCo_y/Ti electrodes with different Ag:Co atomic ratios were further obtained by electrodeposition of Co particles on the den‐Ag/Ti electrode. Polyaniline (PANI) modified den‐Ag/Ti and Ag_xCo_y/Ti electrodes, PANI(n)‐den‐Ag/Ti and PANI(n)‐Ag_xCo_y/Ti, were also obtained by cyclic voltammetry at different numbers of cycles (n) in acidic and alkaline solutions containing aniline, respectively. All these electrodes exhibit high electroactivity for oxygen reduction reaction (ORR) in alkaline solution and their electroactivities follow the order: PANI(15)‐Ag₃₁Co₆₉/Ti>Ag₃₁Co₆₉/Ti>PANI(20)‐den‐Ag/Ti>den‐Ag/Ti. Among them, PANI(15)‐Ag₃₁Co₆₉/Ti displays the highest electrocatalytic activity for ORR with a much positive onset potential of 0 V (vs. Ag/AgCl) and a high ORR current density of 1.2 mA cm^?2 at ?0.12 V (vs. Ag/AgCl). The electrocatalysts are electrochemically insensitive to methanol and ethanol oxidation, and, as cathode electrocatalysts of direct alcohol fuel cells, can resist poisoning by the possible alcohol crossover from the anode.     

Some notes on the impedance method for mechanistic studies of electrode reactions

Conditions for obtaining high precision impedance data on electrochemical metal/electrolyte interfaces are discussed and some results pertaining to several electrode reactions presented. The importance of the dropping mercury electrode is stressed. Published in Elektrokhimiya in Russian, 2009, vol. 45, No. 1, pp. 28–31. Dedicated to Professor B.V. Ershler on the occasion of the Centenary of his birth. The text was submitted by author in English.     

Study on the electroreduction of In(III) ions at gold from acidic bromide solutions by the rotating ring-disc electrode technique

The mechanism of the indium electrodeposition on gold from acidic KBr solutions has been investigated by means of the rotating ring-disc electrode technique. The measurements showed that the overall electrode reaction In(III) + 3 e In consists of two successive charge transfer steps, i.e. In(III) + 2 e In(I) and In(I) + e In, with soluble monovalent indium as an intermediate. The current efficiency for In(I) generation under steady-state conditions is 100% in the case of low disc current densities. The disproportionation of In(I) in the bulk of solution occurs in slightly acidified solutions,pH=2, in addition to the In(I) electrochemical reduction. Based on the ring current transients, it was established that the two-electron transfer step is preceded by the formation of a thin passive film of indium metal.

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Untersuchung der elektrochemischen Reduktion von In(III)-Ionen an Gold in sauren Bromidlösungen mit der rotierenden Ring-Scheiben-Elektrode

Zusammenfassung Mit Hilfe der rotierenden Ring-Scheiben-Elektrode wurde der Mechanismus der kathodischen Abscheidung von Indium auf Gold in sauren KBr-Lösungen untersucht. Aus den Messungen folgt, daß die Bruttoreaktion In(III) + 3e In über zwei aufeinanderfolgende Durchtrittsreaktionen, In(III) + 2 e In(I) und In(I) + e In, mit löslichem einwertigem Indium als Zwischenprodukt abläuft. Bei kleinen Stromdichten werden die In(I)-Ionen mit 100%iger Stromausbeute erzeugt. In schwächer sauren Lösungen (pH=2) konnte außer der elektrochemischen Reduktion von In(I) zusätzlich dessen Disproportionierung innerhalb der Lösung ermittelt werden. Auf Grund der Ringstrom-Zeit-Kurven wurde auch festgestellt, daß die Bildung von einer dünnen In-Metallschicht, die ein passives Verhalten aufweist, dem Zweielektronenübergang vorangegangen ist.

     

Effect of oxygen vacancies in anodic titanium oxide films on the kinetics of the oxygen electrode reaction

The effect of oxygen vacancies in the anodic oxide film on passive titanium on the kinetics of the oxygen electrode reaction has been studied by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Oxide films of different donor density were prepared galvanostatically at various current densities until a potential of 20.0 V_SHE was achieved. The semiconductive properties of the oxide films were characterized using EIS and Mott-Schottky analysis, and the thickness was measured using ellipsometry. The film thickness was found to be almost constant at ∼44.7 ± 2.0 nm, but Mott-Schottky analysis of the measured high frequency interracial capacitance showed that the donor (oxygen vacancy) density in the n-type passive film decreased sharply with increasing oxide film formation rate (current density). Passive titanium surfaces covering a wide range of donor density were used as substrates for ascertaining relationships between the rates of oxygen reduction/evolution and the donor density. These studies show that the rates of both reactions are higher for passive films having higher donor densities. Possible explanations include enhancement of the conductivity of the film due to the vacancies facilitating charge transfer and the surface oxygen vacancies acting as catalytic sites for the reactions. The possible involvement of surface oxygen vacancies in the oxygen electrode reaction was explored by determining the kinetic order of the OER with respect to the donor concentration. The kinetic orders were found to be greater than zero, indicating that oxygen vacancies are involved as electrocatalytic reaction centers in both the oxygen evolution and reduction reactions. This paper was submitted in honor of the many contributions to electrochemistry that have been made by Professor Boris Grafov. The article is published in the original.     

辅酶Ⅰ电化学配位反应机理的紫外光谱电化学研究

用薄层池原位紫外光谱电化学法研究了辅酶Ⅰ(NAD)在银电极上的电化学配位反应机理。实验结果表明：NAD能与溶出的银离子生成配合物，该配合物的配位反应是一种可逆过程，用光谱电化学的Nernst图解分析获得银离子与NAD配合物的主要存在形式是［Ag(NAD)₂］⁺，银离子是与NAD分子的腺嘌呤基团形成配合物的。配合物的银离子与银电极表面发生异相电子交换反应，该电化学反应是受吸附控制的准可逆电极过程。     

高分子微球在电化学领域的应用

本文综述了近几年来高分子微球在电化学领域应用的研究进展。分别介绍了电场作用下微球悬浮液反射光谱的变化,包覆导电聚合物高分子微球的振荡电流和循环伏安特征和二茂铁基高分子微球电极反应的粒径效应,并对各类微球悬浮液的电化学行为及电极反应模型进行阐述。综述表明高分子微球电化学具有广阔的应用前景。     

Electrochemical Systems Based on Sol-Gel Silica Matrix Impregnated with Organic Solvent

Two electrochemical systems based on sol-gel silica matrix impregnated with organic solvent were prepared and studied. The first one is composed of tetramethylorthosilicate based material filled with ferrocene solution in polar solvent: propylene carbonate. Electrodes are immersed in this solid electrolyte during all stages of sol-gel process. Despite of the lack of the extra added salt, by using ultramicroelectrode, undistorted electrochemical signal corresponding to the electrooxidation of the ferrocene was obtained. Its diffusion coefficient within the sol-gel matrix depends on the time elapsed after gelation and it is not much below that in salt solution in the same solvent. The second system is based on graphite dispersion in hydrophobic sol-gel silicate matrix. This material was filled with mixture of liquid butylferrocene and hexadecane. After immersion in aqueous salt solution it serves as working electrode. The electrochemical signal corresponding to the electrooxidation of the butylferrocene within organic phase was obtained. Probably the electrode process occurs at three phase (carbon/organic phase/aqueous phase) junction and it is accompanied by anion transfer through the liquid-liquid interface.