粉末多孔镍电极电化学阻抗谱及其数学模型

镍电极反应动力学在大多情况下是受固态质子扩散过程控制的，以此为出发点建立了具有明确物理意义的镍电极电阻抗谱（ＥＩＳ）的数学模型，并以该模型为基础，讨论了一些模型参数如双电层电容Ｃｄ１，质子扩散系数Ｄ及活性物质粒子半径ｒ０等改变，电极的不同荷电状态及多孔镍电极中的传质过程对镍电阻阻抗谱的影响，理论模型较好地解释了一些实验结果。     

玻碳电极界面的阻抗谱数学表达及定量分析

玻碳电极（GCE）是各类电化学传感器常用的基础电极,其界面特征直接影响检测性能。本文详细考察了电极体系的电化学过程,针对GCE传感界面,探讨了一个等效电路中电解质电阻、电荷输运电阻、扩散阻抗、电化学（氧化/还原）反应阻抗、表面吸附阻抗和双电层电容等电学元件的物理意义,并给出了对应的数学模型。通过改变模型中5个参数值,模拟了不同状态下的阻抗谱,分析了电极系统各参数对GCE阻抗谱的贡献规律。最后,采用该数学模型对裸GCE和修饰GCE在铁氰化钾溶液中的阻抗谱进行分析,拟合结果与实验数据吻合度高;基于拟合获得参数,定量对比分析了修饰前后电极表面的特征变化。     

光谱椭圆法对Ni（OH）_2／NiOOH电化学性质的研究

用现场光谱椭圆偏振技术和电化学实验方法研究了Ｎｉ（ＯＨ）＿２／ＮｉＯＯＨ体系中的电化学反应．拟合椭圆偏振光谱的实验数据确定了阴、阳极过程中镍电极上表面膜的转化模型,结果表明：在镍表面上离子注入钻之后,表面膜转化模型基本保持不变,但Ｎｉ（ＯＨ）＿２／ＮｉＯＯＨ间电化学反应的性质受到明显影响．     

嵌入化合物电极的电化学阻抗谱: 模型与理论模拟

建立了单个嵌入化合物颗粒、混合颗粒、厚度均匀多孔电极层以及非均匀、多层多孔电极层的理论模型,模拟得了了上述模型的相对应电化学阻抗谱（EIS）特征.结果表明,单个颗粒和混合颗粒表现出相似的阻抗谱特征,均由高频区域内与锂离子通过固体电解质相界面（SEI）膜过程相关的R_SEI‖C_SRI半圆,与电荷传递过程相关的R_ct‖C_dl半圆以及锂离子在固体颗粒内部的扩散相关的斜线三部分组成.对于非均匀、多层多孔嵌入电极而言,一个个新奇的现象就是在阻抗谱中会出现三个半圆,影响第三个半圆现现并形成的因素主要为电极中的颗粒尺寸分布以及电极层的厚度分布,也就是说电极片中出现不同尺寸分布的颗粒以及形成薄厚两种电极层的时候,容易导致阻抗谱中出现第三个半圆.     

头孢噻肟钠的极谱伏安行为及其单扫描示波极谱法测定

以多种电化学手段研究了头孢噻肟钠的极谱伏安行为，在磷酸盐缓冲溶液中，头孢噻肟钠产生了一个不可逆吸附不原波，其峰电位为－０．７７Ｖ（ｖｓ．ＳＣＥ）。有二个电子和一个质子参与了电极反应。电极反应速率常数Ｋｓ为９．０×１０＾－６ｃｍ．ｓ＾－１。     

铜在低电导溶液中扩散机理的研究

双水内冷发电机空芯铜导线的腐蚀问题直接影响到火电厂发电机的安全经济运行．其腐蚀体系为纯铜和低电导水溶液（pH＝7．3，空气饱和，电导率＜10μS·cm－1）．我们已经用交流阻抗法对该体系进行了一些研究．由于该体系溶液电导率低，在交流阻抗谱的高频区出现高频半圆；低频区为一条文于实轴Z约45°的直线（不加缓蚀剂时）．如果在该体系中MABTA、MBT等缓蚀剂，低频区直线变为半圆．所以，低频区的阻抗代表了电极表面的特征，而高频区（如10k～100kHz范围）半圆是由于参比回路（包括参比电极、盐桥、鲁金毛细管等）中存在太大的电阻…     

镍纳米线电极的交流阻抗研究

用交流阻抗法研究了一种新型电极－镍纳米线电极在碱性溶液中的电化学行为,给出了相应的等效电路和拟合效果。实验结果表明,外加电位对电极表面化学反应速度和类型有显著影响。在外加电位不高时,Ni（Ⅱ）氧化成Ni(Ⅲ)的电化学过程随着电位的升高而明显加速;当外加电位高于0．40V以后,电极表面同时发生电化学析氧反应。相同条件下,镍纳米线电极的表面电化学反应速度远远高于镍块体电极。     

锆系Laves相储氢合金电极的性能研究

Ｚｒ（Ｖ０．２Ｍｎ０．２Ｍｏ０．０６Ｎｉ０．５４）２．４合金经ＨＦ溶液处理后，合金表面由富Ｚｒ和富Ｍｎ层转变成富Ｎｉ层，从而使电极初期活化周期明显缩短，电极表面氢吸附性能改善。表面反应电阻减小。本文探讨了上述电极表面反应机理，即表面Ｎｉ的催化、氢吸附和氢转移机理，对阻抗谱进行拟合，给出了相应的电极反应等效电路。     

自组装金电极的电化学测试及其FTIR和AFM分析

利用交流阻抗谱测试了自组装免疫电极的抗原响应特性，对生物电极解离过程的机理进行了研究，用傅里叶变换红外反射光谱（FTIR）和原子力显微镜（AFM）对电化学实验过程进行了直观观测和定量分析。     

电化学阻抗谱法测定固态聚合物电解质的本体电阻

采用电化学阻抗谱法,对阻抗谱中的聚合物电解质本体电阻（Rb）与膜厚（L）的关系和固体聚合物电解质/惰性电极间的界面阻抗随直流电压的变化趋势进行了研究.结果表明,阻抗谱中聚合物电解质本体电阻（Rb）含有一定的阻塞电极/聚合物电解质间的界面阻抗;由于界面双电层电容的变化,在直流电压0.15～3 V范围内,界面阻抗随电压的增大而减小.     

A novel titanium-supported nickel electrocatalyst for cyclohexanol oxidation in alkaline solutions

A novel titanium-supported nickel electrode (Ni/Ti) is fabricated by a simple hydrothermal process using hydrazine hydrate as a reduction agent. Its electrocatalytic activity towards cyclohexanol oxidation has been investigated by cyclic voltammetry (CV), chronoamperometry (CA), quasi-steady state polarization and electrochemical impedance spectroscopy (EIS). Effects of various parameters such as potential scan rate and cyclohexanol concentration on the electro-oxidation of cyclohexanol are investigated. Results show that the Ni/Ti electrode behaves as an efficient catalyst for the electro-oxidation of cyclohexanol in basic media and its electrocatalytic activity towards cyclohexanol oxidation is higher than a nickel oxyhydroxide modified nickel electrode (NOMN). It is confirmed that during the anodic potential sweep the electro-oxidation of cyclohexanol follows the formation of NiOOH on the electrode surface and is then catalysed by NiOOH. The rate-determining step for cyclohexanol oxidation is the reaction between the high oxidation state nickel (Ni³⁺) and the adsorbed cyclohexanol on the surface of the Ni/Ti.     

Determination of ionic conductivity and its impact on proton diffusion model for nickel hydroxide

The ionic conductivity is an important but previously ignored aspect for the nickel hydroxide used in alkaline batteries. With a specially designed device, the ionic conductivity is determined for single beads of spherical nickel hydroxide in KOH solutions. The apparent ionic conductivity is found on the order of 10(-3)-10(-2) S cm-1 in 6 M KOH and to change with the conductivity of the solution in which the bead is immersed. The ionic conductivity of the bead can be mainly attributed to the electrolyte absorbed in the bead. On the basis of these findings, the dual structure model for proton diffusion in spherical nickel hydroxide is refined by specifying nanoparticles to be the component showing a large apparent proton diffusion coefficient (on the order of 10(-7) cm2 s-1). This refined model is able to interpret the main features of the diffusion coefficients reported in the literature, including the unusually large scattering (up to 6 orders of magnitude) and inconsistency in the dependence of proton diffusion coefficient on the state of the charge. Besides, this refined model is supported by the influence of bulk KOH concentration on chronoamperometry and transmission electron microscopy observations.     

贮氢电极电化学阻抗谱及其数学模型

从分析贮氢电极的放电过程着手，建立了具有明显物理意义贮氢电极电化学阻抗谱的数学模型，以该数学模型为基础，讨论了与电极材料性质和电极荷电状态相联系的一些参数。     

Electrochemical behaviors of novel electroactive Au nanoparticles protected by self-assembled monolayers

There has been substantial recent interest in studying monolayer-protected gold clusters (MPCs) owing to their diverse applications. The present work is an electrochemical study of novel gold nanoparticles covered with a monolayer of mercapto-dodecanol ended chloro-dicyano-quinone (HS-C12O-CDQ), which was adsorbed on the electrode (CDQ-MPCs film). Our findings reveal a redox behavior for CDQ-MPCs film similar to the solution electrochemistry of dichloro-dicyano-quinone. Furthermore, a diffusion-like mechanism was found for electron transfer, which may have occurred due to proton diffusion towards or outwards the electrode through the film casted. Chronoamperometry confirmed diffusion behavior of the ET process. Finally, EIS was used to find the rate constant of ET process for the redox reaction that occurred and the contribution of MPCs in total interfacial capacitance.     

Proton diffusion determination and dual structure model for nickel hydroxide based on potential step measurements on single spherical beads

Potential step measurement is carried out on single beads of spherical nickel hydroxide to determine the proton diffusion coefficient (D) and concentration of the effective proton vacancies (C). The semi-infinite diffusion equation for the initial stage and the finite diffusion equation for the long-term of the current response to potential step are used for deducing the D and C values. The diffusion coefficients deduced from short and long-term current responses are in the order of magnitude 10(-7) and 10(-10) cm2 s(-1), respectively. The sum of the effective proton vacancy concentrations associated with the two D values comes out to be equal within experimental error to the effective proton vacancy concentration converted from the released electricity during discharge. A dual structure model is proposed to interpret the above-mentioned findings, featuring densely packed grains within which proton diffusion is slow and an inter-grain matrix where proton diffusion is fast. With this model the huge difference (about 6 orders of magnitude) in D values reported in the literature as well as the controversy of the dependence of diffusion coefficient on the state of charge can be largely rationalized. This dual structure model is supported by SEM and AFM observations.     

钡添加剂对二次碱性锌电极性能的影响

采用直接化学合成法制备以钡作添加剂的二次碱性锌电极活性物质,样品的表面形貌及其晶态结构由SEM和XRD表征,并以循环伏安、充放电循环及电化学阻抗谱测定样品的电化学性能.实验表明,锌电极因Ba的添加而生成一种化学式为BaZn(OH)4·xH2O的锌酸钡,改善了电极的电化学性能.此外发现,Zn电极的电化学阻抗谱含有一个对应于电极表面放电产物覆盖率的时间常数.     

旋转玻碳电极上二茂铁的电化学阻抗行为及其与DNA的相互作用

应用旋转圆盘电极和电化学阻抗法研究了二茂铁在Tris-NaC l(pH=7.2)缓冲溶液中于旋转玻碳电极上的电化学阻抗行为及其与DNA的相互作用.结果表明,二茂铁于旋转电极的伏安曲线呈现明显的极限电流平阶,而其交流阻抗谱则出现两个电容弧.二茂铁与DNA的作用,若受扩散过程控制则其极限扩散电流随DNA浓度增大而减小,而在电化学控制过程中则表现为电化学反应电阻随DNA浓度增大而增大.根据旋转圆盘电极和电化学阻抗谱测试,表明由这两种方法数据拟合求得的二茂铁条件电位速率常数能够很好地相互吻合,但如存在DNA时,则其条件电位速率常数有一定程度的减小.     

不同阳极电位下铝青铜的电化学阻抗谱研究

应用电化学阻抗谱(EIS)方法研究了铝青铜的腐蚀溶解机制.结果表明,在活性溶解区,铝青铜以氯化络合物的形式溶解,并且CuCl2的扩散是该溶解过程的控制步骤;而在过渡区,铝青铜的EIS谱出现第2个容抗弧,这是由于CuCl络合物和氧化腐蚀产物在电极表面沉积成膜所致;在极限电流区,腐蚀产物膜产生破损点,导致电极表面快速溶解,产生严重的点蚀,这就是在该区域极化电位下EIS出现感抗弧的原因.     

钴的添加形式对氢氧化镍电极性能的影响

研究了钴元素分别以Co ,CoO ,Co +CoO三种形式作为添加剂并分别以与Ni(OH) 2 用机械混合的方式添加到电极活性物质中时对镍电极性能的影响 ,用循环伏安法和电化学交流阻抗法对实验结果进行分析 .结果表明 :对于机械混合的添加方式 ,Co ,CoO和Co +CoO三种形式的钴添加剂均可在一定程度上改善镍电极的性能 .其中 ,当钴以CoO的形式添加时镍电极的性能最好 .这是因为三种形式的添加剂均在一定程度上改善了活性物质Ni(OH) 2 的结构、增强了电极中质子的传输能力 ,从而提高了镍电极反应的可逆性 ,强化了镍电极的析氧极化 ,并提高了镍电极的充电效率 ,其中CoO的作用效果最明显 .