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。     

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化学阻抗谱（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C（d1）、质子扩散系数D及活性物质位于半径γ0等的改变，电极的不同行电状态以及多孔镍电极中的传质过程对镍电极阻抗谱的影响．理论模型较好地解释了一些实验结果．     

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。     

纳米TiO2膜电极的电化学阻抗谱

纳米TiO2膜电极的电化学阻抗谱;纳米TiO2膜;电化学阻抗谱;催化电极;异相氧化还原电对     

电催化界面和反应的电化学阻抗谱研究：经典永不褪色

本文章综述了电催化领域电化学阻抗谱（EIS）的相关研究. 首先概述了从二十世纪初到现在这一专业领域的发展历史. 然后介绍了电催化阻抗理论的几个里程碑. 其中,着重介绍了目前分析电催化EIS数据的主流模型——Dolin-Ershler模型. 之后,具体讨论了铂金单晶的双电层电容,特别是围绕这一基础课题的实验和理论上的挑战. 我们质疑采用Dolin-Ershler模型获取稀溶液中双电层电容的合理性. 因为在稀溶液中,双电层效应使得双电层电容具有频散特性,因而双电层电容的低频部分在分析过程中可能被遗失了. 未来,我们期待看到新的实验去证明或反驳一个最近的理论预测,即铂电极在氧化物生成电位区域中具有非单调表面电荷关系和负双电层电容.     

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。     

普鲁士蓝膜修饰电极的电化学阻抗谱

测量了应用电化学方法制备的不同厚度的普鲁士蓝膜修饰电极的循环伏安行为与电化学阻抗谱.由所得到的循环伏安图讨论了普鲁士蓝修饰膜的氧化还原过程,并对相关的Nyquist图进行了解析,提出了相应的等效电路.在此基础上计算出较薄膜中普鲁士蓝/普鲁士白电化学反应的表观速率常数和表观扩散系数,讨论了膜厚度对电荷扩散的影响.当膜相对较薄时,电极过程主要由动力学过程控制;当膜达到一定厚度时,电荷在膜中的扩散速率受到限制,电极过程由动力学过程和电荷扩散过程共同控制,证实了文献报导的普鲁士蓝膜修饰电极为多层空间分布电荷传递模型.     

宏观均相多孔电极电化学阻抗谱基础

电化学阻抗谱可用于诊断多孔电极内电荷转移反应,即界面电荷集聚和电荷传导,以及反应物质输运。本文采用复相量方法,在同态假设条件下,重新推演多孔电极阻抗谱模型,厘清传统多孔电极阻抗谱模型中的模糊性表述。(1) 定义多孔电极表征输入参数,包括电极基体电子电导率σ₁ 、电解质离子电导率σ₂、界面电荷传递电导率g_ct、单位面积界面电容C、固相扩散系数D、速度常数k、电极厚度d、特征孔深L_p 和单位体积表面积S_c;(2) 解析阻抗谱特征输出参数,包括场扩散常数K,特征频率ω₀、ω₁、ω₂、ω₃和 ω_max,它们分别相关于界面传导反应、有限场扩散、氧化还原反应、孔内扩散和最小特征孔尺寸,以及分别对应于从传导到扩散和从扩散到饱和的转折频率f_k1 和f_k2;(3) 当参数X和Z同时变化时(X = σ₁和Z = d,S_c,L_p,C,g_ct,D,k),通过阻抗谱特征参数的演变规律,分析了电荷转移反应中X和Ζ参数耦合竞争;(4)为深入分析电荷转移反应中参数X和Z的耦合竞争,引入了分叉频率f_XZ和f_ZX 。f_XZ和f_ZX所处位置可以用于表征参数X和Z影响电荷转移反应的深度和广度。当分叉频率f_XZ和f_ZX不存在时,表明电荷转移反应中参数X和Z在全频率范围内存在耦合竞争。总之,借助于特征频率和分叉频率,本文一方面研究了动力学参数和微观结构参数对多孔电极中电荷转移反应的影响,另一方面分析谱图的变化及其背后的阻抗谱特征演化规律。本文研究结果可为阻抗谱的系统仿真和辨识提供理论基础,可为多孔电极内电荷转移反应的竞争分析提供技术支撑,还可为电化学储能系统的优化设计提供诊断工具。     

肾上腺素电化学氧化的交流阻抗研究

肾上腺素是人体内的重要激素,为单胺类物质属儿茶酚胺系列.肾上腺素的生物合成中间产物多巴胺是脑神经递质,它们都具有很强的生理活性.七十年代以来,神经递质的在体(in vivo)电化学测定已有大量研究,而有关电化学氧化机理的研究报导却不多.对该类物质的电化学氧化机理进行研究,不仅有助于其在体电化学测定研究,也有助于揭示它在生理条件下的氧化机制.我们曾对肾上腺素在硫酸介质中,玻碳电极上的循环伏安特性进行过研究.结果表明,其循环伏安谱仅呈现出一对氧化-还原峰(E_(1/2):0.146mV);氧化峰和还原峰的谱形较为尖锐、对称性亦较强;其蜂电流与电势扫描速度v 成正比,而不是扩散物质的能斯特波中所表现出的那种v~(1/2)关系,即其谱图具有法拉第吸附/脱附的特征.在此基础上,本文对肾上腺素在该体系中的交流阻抗特性进行了研究,测得有关电极过程的一些动力学参数,初步推断了其电化学氧化的反应机理。     

液/液界面的电化学阻抗谱测量Ⅰ: 四电极系统中各类界面阻抗的分析

本文系统地研究了将阻抗谱技术应用于液/液界面电化学领域时所出现的问题。提出了四电极系统中液/液界面交流阻抗的表达式。从理论上分析了电解池参数和仪器输入参数对所得交流阻抗曲线的影响。     

Electrical probing of endothelial cell behaviour on a fibronectin/polystyrene/thiol/gold electrode by Faradaic electrochemical impedance spectroscopy (EIS)

The electrochemical impedance spectroscopy (EIS) technique has been shown to be an effective tool for monitoring endothelial cell behaviour on a multilayer functionalised gold electrode. Polystyrene, a reproducible model substrate, is deposited as a thin layer on a thiol functionalised gold electrode. Fibronectin, a protein promoting endothelial cell adhesion, is then adsorbed on the polystyrene surface. The different steps of this multilayer assembly are characterized by Faradaic impedance. The charge transfer resistance and the capacitance for the total layer are modified at each step according to the electrical properties of each layer. This gives the endothelial cells' electrical state in terms of its resistive and capacitive properties. In this study, the endothelial cell layer presents a specific charge transfer resistance equal to 1.55 kOmega cm(2) with no large defects in the cell layer, and a specific capacitance equal to few microF cm(-2) explained by the existence of pseudopods. These electrical properties are correlated to the endothelial cell viability, adhesion and cytoskeleton organization.     

Electrochemical impedance spectroscopy analysis of chalcopyrite CuFeS2 electrodes

A chalcopyrite CuFeS₂ electrode obtained from the “El Teniente” mine has been studied by Electrochemical Impedance Spectroscopy (EIS) in an alkaline solution for different oxidation potentials. The experimental results can be interpreted from a Randles equivalent circuit, V_dc<0.4 V vs. saturated calomel electrode (SCE), and a surface layer model for V_dc>0.4 V vs. SCE. From these results, the variation with the d.c. applied potentials of charge transfer electrical resistance of the redox reaction, the double layer capacitance and other characteristic parameters are considered.     

Sweat Based-multiplexed Detection of NPY-Cortisol for Disease Diagnostics and Stress Management

Cortisol and Neuropeptide Y(NPY) are chronobiological markers of stress. Non-invasive tracking of these two biomolecules can provide great insight into an individual's physiological and neurological wellbeing. This work presents the development of a platform that tracks the two biomarkers in ultra-low volumes (5 μL) of sweat using electrochemical impedance spectroscopy (EIS). The sensing platform was able to detect both molecules in their relevant physiological ranges (8.16–141.7 ng/mL and 50–200 pg/mL respectively) with good sensitivity and specificity. This platform is envisioned to aid in the monitoring of pathophysiologies of stress-based disorders.     

有机涂层失效过程的电化学阻抗和电位分布响应特征

结合使用电化学阻抗谱(EIS)和扫描Kelvin探针(SKP)技术研究了在质量分数为3.5%的NaCl溶液中的铁基有机涂层劣化过程特征. 结果表明, 根据EIS和SKP的响应特征, 可将涂层劣化过程分为3个主要阶段: (Ⅰ) 涂层渗水阶段. 此时, 涂层渗水阶段的EIS阻抗持续减小, 但保持单容抗弧特征, SKP特征是电位持续降低, 但分布保持均匀; (Ⅱ) 基底金属腐蚀发生阶段. 此时, EIS阻抗快速下降, 并产生第二时间常数; SKP特征为表面电位差增大; (Ⅲ) 基底金属腐蚀发展与涂层失效阶段. 此时, EIS出现扩散尾, SKP电位差保持较大数值. 实验结果表明, 在研究有机涂层劣化过程中, EIS和SKP的结合使用能够互相补充完善, 获得涂层劣化过程中更为准确\, 可靠的变化信息.     

阻抗谱定量分析金属/有机涂层界面粘接力

采用传输线类型的CR电路解析阻抗谱得到离散的电容参数,它们随离散特征频率变化的线性区间斜率与有机涂层/金属界面的瞬时脱层速率有关,不受缺陷位置腐蚀产物的影响,重现性好.建立了阻抗谱与粘结力的定量关系和数据处理方法,并进行了验证,说明了精度较高的原因.用硅烷直接预处理,或者磷化、热浸锌后再处理,会明显影响A3钢与环氧粉末涂层之间的粘结力.     

土壤中钢铁表面防护层缺陷的电化学检测

基于电化学阻抗谱技术建立了实验室检测钢铁表面防护层破损与剥离的电化学方法。提出了在一定频率范围内以电极阻抗幅值比Ｋ的变化关系作为防护层缺陷状态的表征。用此方法测定了土壤中阴极保护的表面涂覆不同状态石油沥青防护层的Ａ３钢模拟度片,得到了较为满意的结果。     

操作条件对DMFC阴极电化学阻抗谱参数的影响

通过降低阴极催化剂载量强化了阴极氧还原反应的电化学极化, 测量了不同操作条件下直接甲醇燃料电池(DMFC)的极化曲线和交流阻抗谱,并提出了改进的等效电路模型LR(CR)(QR(LR))用以分析温度、空气流量和甲醇流量对DMFC阴极电化学反应和传质极化过程的影响. 研究结果表明, 提高工作温度会导致更多的甲醇渗透到阴极, 加大阴极氧气还原反应的电荷转移电阻; 只有采用大的空气流量,才会有效地防止水淹, 加大氧气向催化剂层的传质, 促进阴极反应的进行; 适当提高甲醇的流量可以促进阳极和阴极电化学反应的进行, 但是过高的甲醇流速可能会降低电极表面的温度, 加剧甲醇的渗透.     

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.     

A High Sensitive,Reproducible and Disposable Immunosensor for Analysis of SOX2

In this study, an ITO (indium tin oxide) based biosensor was constructed to detect SOX2. SOX2 helps the regulation of cell pluripotency and is closely related to early embryonic development, neural and sexual differentiation. SOX2 is amplified and overexpressed in some malignant tumors such as squamous cell, lung, prostate, breast, esophageal cell, colon, ovarian, glioblastoma, pancreatic cancer, gastric cancer, head and neck squamous cell carcinoma. To generate a hydroxylated clean electrode surface, ITO electrodes were treated with NH₄OH/H₂O₂/H₂O. Later, ITO‐PET electrode surfaces were modified with 3‐glycidoxypropyl trimethoxysilane (3‐GOPS). Then, Anti‐SOX2 was covalently immobilized onto the electrode surfaces. 3‐GOPS concentration, Anti‐SOX2 concentration and incubation time, SOX2 incubation time were optimized. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were utilized in order to follow up the immobilization processes and the optimization steps of the biosensor. To characterize the analytical properties of constructed immunosensor; linear range, repeatability, reproducibility and regeneration studies were investigated. The linear range of the immunosensor was detected as 0.625 pg/mL–62.5 pg/mL. Square wave voltammetry technique was also applied to the biosensor. Storage life of the biosensor was determined for identifying the possible usability of the biosensor in clinical field. Finally, the designed biosensor was applied to the real human serum samples. The results obtained with the presented biosensor were also compared with ELISA results.     

Investigation of Active and Inactivated Yeast Cells by Scanning Electrochemical Impedance Microscopy

Scanning electrochemical microscopy (SECM), electrochemical impedance spectroscopy (EIS) and scanning electrochemical impedance microscopy (SEIM) were used to investigate electrochemical activity of active and inactivated yeast Saccharomyces cerevisiae cells. SEIM experiment was performed using a unique electrochemical impedance spectrometer with a fast Fourier transform (FFT‐EIS) function, which enabled simultaneously perturb/evaluate electrochemical system at 50 frequencies. This allowed very quick observing the differences between impedance spectra, which were taken every few seconds. Therefore, we were able to apply SEIM for relatively fast determination of electrochemical impedance dependence on the distance between ultramicroelectrode (UME) and surface modified by immobilized yeast cells. It was determined that electrochemical activity and ‘breathing’ (a consumption of dissolved oxygen) of yeast can be electrochemically observed when the distance between UME and surface of yeast cells is in the range from 0 μm to 25 μm. Therefore, 25 μm is the maximum distance suitable for efficient investigation of yeast cell activity when experiments are performed in FFT‐SEIM mode. Charge transfer resistance of active and inactivated yeast cells was determined using EIS. It was calculated that charge transfer resistance of active yeast cells is 1.5 times lower than that of inactivated yeast cells. Lipophilic vitamin K₃ (Vit‐K₃) and hydrophilic vitamin K₁ (Vit‐K₁) were mixtured and used as redox mediators for charge transfer from yeast cells.