扫描电化学显微镜原位表征pH值对核电蒸汽发生器合金腐蚀行为的影响(英文)

用扫描电化学显微镜(SECM)和电化学阻抗谱(EIS)原位表征了溶液pH值对核电蒸汽发生器800合金溶液中的腐蚀行为的影响.实验结果表明:在酸性氯化钠溶液中,SECM探针渐进曲线为正反馈,表明800合金为活化阳极溶解,腐蚀电位下的EIS图呈现完整的单容抗弧特征;而在中性或者碱性溶液中,SECM探针渐进曲线为负反馈,表明800合金为自钝化,不同阳极电位下的EIS图均呈现不完整的容抗弧特征,但随着阳极极化电位的增加,EIS谱容抗弧半径减小,表明钝化膜的耐蚀性下降;SECM二维扫描图像结果显示探针电流增加,表明电极表面活性增加,即钝化膜的溶解速度增加.而在中性或者碱性溶液中的SECM二维图像中均可观察到若干活性点,这可能与晶界或者金属夹杂物等有关.     

海洋微生物对316不锈钢的电化学腐蚀行为

采用自腐蚀电位、电化学极化曲线、电化学阻抗谱技术研究了316不锈钢在无菌培养基介质和海水微生物接种培养有菌培养基介质中不同周期的腐蚀行为．结果表明,316不锈钢电极在有菌介质中比在无菌介质中的腐蚀电流密度大,腐蚀电位负移,微生物加速了不锈钢的腐蚀速度．随着浸泡时间的增加,有菌介质中的不锈钢电极极化电阻值逐渐减小,表明了海洋微生物的附着和繁殖加速了316不锈钢的腐蚀速率,降低了其在海洋环境中的耐蚀性．     

锈层下碳钢和耐候钢的微区和宏观腐蚀电化学行为

采用扫描电化学显微镜(SECM), 辅以极化曲线和电化学阻抗谱(EIS), 并结合SEM和XRD研究了耐候钢和碳钢在干湿交替环境下的腐蚀行为, 包括微区阳极溶解过程和阴极还原行为、 宏观腐蚀过程和微观结构及组成等. SECM测试结果表明, 锈层下碳钢和耐候钢的腐蚀过程都受阳极控制, 锈层的存在促进氧的还原. 宏观和微区电化学测试结果均表明, 在实验周期内, 初期形成的锈层降低了Fe阳极溶解速率, 从而提高碳钢和耐候钢的耐蚀性能, 后期形成的锈层由于其组成和结构特征的变化, 2种钢的腐蚀速率增加; 同时耐候钢的腐蚀速率较碳钢大, 且氧还原也较碳钢强, 有利于锈层的形成, 从而有利于长期的防护, 但是耐候钢的锈层在短期内并没有很好的保护性. 锈层不够致密, 呈疏松多孔状, 其组成主要有晶态的γ-FeOOH, Fe₃O₄和γ-Fe₂O₃等, 相同的干湿循环条件制备的耐候钢锈层较碳钢厚.     

扫描电化学微探针的发展及其在局部腐蚀研究中的应用

简要概述当前国内外具有空间分辨能力的扫描微探针技术及其在腐蚀研究中的应用,包括扫描微电极技术(SMET)、扫描电化学显微镜(SECM)、原子力显微镜(AFM)、扫描Kelvin探针技术(SKP)等,其中SMET、SECM、SKP及局部交流阻抗技术可直接测定腐蚀电极表面或界面电化学不均一性的分布图像,而原子力显微镜技术则是通过分子间作用力从纳米尺寸测量腐蚀过程表面形貌的变化.文中侧重介绍作者近年先后建立的具有微米空间分辨度的电化学微探针技术,并利用各种扫描探针技术研究金属/溶液界面电化学不均一性及其局部腐蚀过程.研究表明,空间分辨电化学方法的发展及应用,加深了人们对金属表面和金属/溶液界面电化学不均一性,特别是金属局部腐蚀发生、发展及过程机理的认识.     

微量钪添加对Al-Cu合金时效析出及电化学腐蚀行为的影响

采用透射电子显微镜及三维原子探针观察及统计分析研究了0.3%(质量分数)Sc添加对Al-2.5%Cu合金时效析出行为的影响,采用电化学分析方法对比了Sc添加前后合金的电化学腐蚀行为,藉此建立了时效析出第二相与电化学腐蚀性能之间的关联并阐明了Sc的微合金化作用。研究结果表明:Sc的加入显著影响了Al-Cu合金中θ’-Al2Cu的析出,使得析出相密度增加尺寸减小,同时由于Sc原子在析出相/基体界面的偏聚降低了界面能,从而影响了合金的电化学腐蚀行为,使得含Sc合金的耐蚀性明显优于纯Al-Cu合金。结果可以为耐腐蚀、高性能Al-Cu合金的微合金化材料设计提供参考。     

化学镀镍磷合金在浓NaOH溶液中的电化学腐蚀行为

微观结构;腐蚀电化学;化学镀镍磷合金在浓NaOH溶液中的电化学腐蚀行为     

基于扫描电化学显微镜的微生物电化学研究进展

微生物是自然界中广泛存在的生命体,它们通过呼吸代谢转化碳水化合物并产生能量的过程与电子转移密切相关,在元素的生物地球化学循环与物质能量转化过程中发挥着关键作用.因此,微生物电化学的原理及其应用近年来备受关注.电化学及其联用技术能够从电子转移层面揭示微生物/非生物界面物质和能量转化机制,是直接、有效的分析手段.其中,扫描...     

铜的腐蚀电化学行为及应用综合实验设计

以纯铜为研究对象,采用开路电位、动电位极化曲线和交流阻抗谱（EIS）等电化学方法和扫描电镜（SEM/EDS）技术研究了铜在模拟海水中的腐蚀电化学行为和机理。本实验涉及电解质溶液、原电池和电解池的相关知识,同时还涉及表面形貌及成分分析等相关知识,并将这些知识应用于金属腐蚀研究中,综合性较强,可作为大学本科生二年级或研究生一年级的综合实验教学内容。     

覆铜板在NaCl溶液中的腐蚀电化学行为

应用线性极化、循环伏安(CV)及电化学阻抗谱(EIS)等电化学方法对覆铜板(CCL)和纯铜的腐蚀电化学行为进行了研究和比较. 结果表明, 覆铜板的耐蚀性弱于纯铜, 其阳极溶解过程与纯铜有所不同; 在较低电位下, CCL 以铜的氯化络合物的形式溶解, CuCl-2的扩散为该过程的控制步骤; 随着电位的升高, 腐蚀产物CuCl在电极表面形成疏松多孔的膜, Cl-在膜中的传输成为溶解过程的控制步骤. 电极表面CuCl 膜的消长过程是产生感抗弧的主要原因.     

水性环氧铝粉涂层/碳钢体系的腐蚀电化学行为

应用电化学阻抗谱(EIS)和扫描振动电极技术(SVET)研究了碳钢基体上含人造缺陷的水性环氧铝粉涂层浸泡在3.5%NaCl溶液中的腐蚀电化学行为.结果表明,浸泡初期,涂层缺陷处为阳极活性区,涂层阻抗随时间延长逐渐降低,活性区逐渐扩展;之后,由于腐蚀产物的自修复作用使整个涂层/金属界面电化学反应活性降低,导致涂层阻抗快速增加.浸泡后期,由于腐蚀介质渗入到涂层/基体界面,出现了更多的阳极活性区,涂层产生破坏剥离.     

ITO基底上ZnO薄膜的制备以及刻蚀图形的扫描电化学显微镜表征

在氧化铟锡(ITO)导电玻璃的衬底上,利用直接电沉积方法制备了ZnO纳米线或ZnO薄膜.然后利用存储有HCI刻蚀剂的琼脂糖微图案印章对其进行了化学刻蚀以形成不同的图形.利用扫描电子显微镜(SEM)、X射线衍射(XRD)和扫描电化学显微镜(SECM)分别对ITO衬底上的ZnO薄膜的结构、形貌和电化学性质进行表征.     

Development of a Temperature-pulse Enhanced Electrochemical Glucose Biosensor and Characterization of its Stability via Scanning Electrochemical Microscopy

Glucose oxidase (GOx) is an enzyme frequently used in glucose biosensors. As increased temperatures can enhance the performance of electrochemical sensors, we investigated the impact of temperature pulses on GOx that was drop-coated on flattened Pt microwires. The wires were heated by an alternating current. The sensitivity towards glucose and the temperature stability of GOx was investigated by amperometry. An up to 22-fold increase of sensitivity was observed. Spatially resolved enzyme activity changes were investigated via scanning electrochemical microscopy. The application of short (<100 ms) heat pulses was associated with less thermal inactivation of the immobilized GOx than long-term heating.     

Progress in Scanning Electrochemical Microscopy by Coupling with Electrochemical Impedance and Quartz Crystal Microbalance

Scanning electrochemical microscopy (SECM) is a powerful technique for performing quantitative measurements at a local scale. This paper covers the development of combinations of SECM with electrochemical impedance spectroscopy (EIS) and electrochemical quartz crystal microbalance (EQCM). Basic aspects are described and potential applications reported by several research groups are covered. The unique advantages of the coupled techniques—with additional information being obtained from each coupling—are also discussed.     

Determination of Paracetamol in Presence of Ascorbic Acid in Pharmaceutical Products by Scanning Electrochemical Microscopy

The selective amperometric determination of paracetamol in pharmaceutical formulations containing ascorbate was achieved by removing the interfering species in the diffusion layer created between a platinum substrate and a disc microelectrode in a Scanning Electrochemical Microscopy (SECM) configuration, while the target analyte was kept unconsumed. After complete depletion of ascorbate, paracetamol was detected at the SECM tip in a free‐interference solution zone. The influence of the substrate potential and the gap distance on the efficiency of ascorbate removal was systematically examined. The effectiveness of the device towards the determination of paracetamol in pharmaceutical samples was evaluated and under optimal conditions the results obtained agreed well with the labeled value.     

Fabrication of Active Horseradish Peroxidase Micropatterns with a High Resolution by Scanning Electrochemical Microscopy

We used a new reactive species OH^? to fabricate active horseradish peroxidase (HRP) micropatterns with a high resolution by scanning electrochemical microscopy (SECM) coupled with a carbon fiber disk electrode as the SECM tip. In this method, except for active HRP micropatterns predesigned other regions on a HRP‐immobilized substrate were deactivated by OH^? generated at the tip held at ?1.7 V in 1.0 mol/L KCl containing 2.0×10^?3 mol/L benzoquinone (BQ) (pH 8.0). The feedback mode of SECM with a tip potential of ?0.2 V was used to characterize the active HRP micropatterns in 1.0 mol/L KCl containing 2.0×10^?3 mol/L BQ and 2.0×10^?3 mol/L H₂O₂.     

Impacts of Forced Convection Generated via High Precision Stirring on Scanning Electrochemical Microscopy Experiments in Feedback Mode

In this study, the effects of forced convection on scanning electrochemical microscopy (SECM) experiments in feedback mode using ferrocenemethanol as redox mediator are presented. Forced convection, which enhances the mass transfer inside the system, was generated via an electrical high precision stirrer integrated into the SECM setup. A thin‐film interdigitated array electrode serving as model substrate was investigated with probe scan curves in z‐direction and SECM imaging in constant height mode utilizing ultramicroelectrodes (UME) with diameters (d_probe) of 25 μm and 12.5 μm. It was found that forced convection increased the overall current during SECM imaging without distorting distinctive features of the imaged structure when working with a 25 μm UME at substrate‐to‐tip distances of 14 μm and 11 μm. Furthermore, the electrochemical contrast was improved under hydrodynamic conditions for a substrate‐to‐tip distance of 11 μm and scan rates of 5 μm s^?1, 10 μm s^?1, 20 μm s^?1 and 40 μm s^?1. When further decreasing the gap between the UME and the substrate to 9 μm almost no effects of the forced convection were observed. Consequently, for a 25 μm UME, forced convection led to higher currents and improved performance during SECM experiments in feedback mode at substrate‐to‐tip distances of 14 μm and 11 μm, whereas no effects were observed for a 12.5 μm UME at a distance of 8 μm.     

扫描电化学显微镜用于研究生物膜微环境的电子传递

生物电化学系统(BESs)的核心是生物膜在电极/溶液界面的电子传递反应,研究生物膜微区环境中的电子传递有助于阐明微生物的胞外电子传递(EET)机制,从而有针对性地提高BESs中的电子转移效率。微生物的EET机制包括直接电子传递和间接电子传递,由于生物膜组成复杂,含有多种分泌物、胞外聚合物等,常规电化学方法只能从生物膜宏观层面研究EET机制,无法有效区分这两种电子传递途径的贡献。本文采用电化学循环伏安方法研究了电子穿梭体二茂铁甲醇(FcMeOH)与希瓦氏菌(Shewanella)相互作用的界面过程;基于扫描电化学显微技术构建了穿透模式,通过微电极介导FcMeOH与Shewanella反应,收集仅来自间接电子传递途径产生的电流,同时测定了Shewanella在电极/溶液界面的氧化还原性质和空间分布。本论文将电化学扫描探针显微技术应用于EET的研究,从物理化学角度揭示微生物在代谢过程中与外界的电子传输机制。     

5083铝合金在海水中的腐蚀电化学行为及活性氯影响研究

采用动电位极化、循环极化和全浸腐蚀试验方法,研究了5083铝合金在静止海水中的腐蚀电化学性能以及活性氯的影响.结果表明,在本文设置的防污活性氯浓度范围(0.2～0.5mg/L)内,活性氯对铝合金的阴极和阳极电化学极化以及腐蚀行为没有明显影响,并可提高铝合金的耐点蚀能力,海水的pH值对铝合金的腐蚀具有显著的影响.该研究为海水中5083铝合金的防腐防污提供了依据.     

Application of AC impedance techniques to Scanning Electrochemical Microscopy

Fundamental aspects of alternating current Scanning Electrochemical Microscopy (AC-SECM) have been studied. In particular, the flow of AC currents in the cell and simplified equivalent circuit diagrams are discussed. In the case of conductive substrates, the local (1^st and 2^nd order) impedance characteristic of the substrate is presented as a function of DC potential. 3-D imaging of mixed substrates (containing both conductive and non-conductive areas) was performed in the supporting electrolyte alone, without an added redox mediator.Dedicated to Professor Zbigniew Galus on the occasion of his 70^th birthday.     

Study on Electrocatalytic Activity of Platinum for Hydrogen Oxidation in Acidic Solution by Scanning Electrochemical Microscopy

The electrocatalytic activity of platinum for hydrogen oxidation in 0.01 M H₂SO₄ + 0.1 MNa₂SO₄ solution has been investigated by scanning electrochemical microscopy (SECM) technique. The cyclic voltammogram (CV), approach curve, area scan imaging and chronoamperometric methods have been used. The results indicate that the imaging capability of the SECM feedback mode can be used more efficiently to visually identify materials' electrocatalytic activity, compared with the approach curve method for identification of the conductive or insulating nature of a surface. The SECM imaging method has demonstrated the effects of Pt substrate potential on the electrocatalytic oxidation of hydrogen under a constant tip potential. It is found that the more positive the Pt substrate potential, the lower the electrocatalytic activity of the Pt. Furthermore, the chronoamperometric results support the variation of the electrocatalytic activity with the Pt substrate potential as well.