在多晶电极上的伪单晶电化学:可视化上的颗粒和颗粒边界的活性,用于Fe2+/Fe3+氧化还原反应
Barak D B Aaronson1, Chang-Hui Chen, Hongjiao Li
1Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK.
Journal of the American Chemical Society
|February 15, 2013
概括
扫描电化学细胞显微镜 (SECCM) 和电子反射散射 (EBSD) 揭示了电极表面结构如何影响电化学反应. 这项技术在聚晶金电极上绘制单个粒度和粒度边界的活动图.
科学领域:
- 电化学 电化学 电化学
- 材料科学 材料科学 材料科学
- 表面科学是一门学科.
背景情况:
- 电极表面结构显著影响电化学反应速率和机制.
- 在复杂,异质的表面上探测局部电化学仍然是一个挑战.
- 具有固有的结构异质性的多晶电极被广泛使用.
研究的目的:
- 为了证明扫描电化学细胞显微镜 (SECCM) 与电子反射散射衍射 (EBSD) 结合,在多晶电极上进行高分辨率的电化学测量.
- 为了将局部表面结构与单个粒度和粒度边界的电化学活性相关联.
- 为了研究不同晶体学方向的金表面上的Fe(2+/3+) 对的电化学行为.
主要方法:
- 使用高空间分辨率的SECCM进行局部电化学测量.
- 使用EBSD进行详细的表面结构和结晶学方向分析.
- 在多晶电极的单颗粒上进行"伪单晶"电化学测量.
主要成果:
- 对于Fe2+/3+) 对,观察到局部表面结构和电化学活性之间的强烈相关性.
- 在具有显著 (101) 导向贡献的白金颗粒上发现了较高的电化学活性,而不是在化物介质中具有 (001) 和 (111) 贡献的白金颗粒.
- 在硫酸盐介质中,在单个颗粒之间观察到微小的活性变化,但在Fe2+) 氧化过程中在颗粒边界检测到显著增强的活性.
结论:
- SECCM-EBSD是一种有效的方法,用于将多晶电极上的局部表面结构与电化学活性相关联.
- 单个粒的特定晶体学定位会影响电化学活性,这与单晶研究一致.
- 聚晶金电极上的粒度边界可以显著增强电化学活性,特别对宏观尺度行为作出贡献.
相关概念视频
Electrodeposition
Electrodeposition is a technique used to separate an analyte from interferents by electrochemical processes. Here, the analyte is a metal ion that can be deposited on an electrode immersed in the sample solution. The electrochemical setup consists of an anode and a cathode. When an electric current is applied to the setup, oxidation occurs at the anode. At the cathode, which consists of a large metal surface, metal ions undergo reduction and deposit onto the surface.
Electrodeposition can...
Electrodeposition can...
Ladder Diagrams: Redox Equilibria
Ladder diagrams are useful tools for understanding redox equilibrium reactions, especially the effects of concentration changes on the electrochemical potential of the reaction. The vertical axis in the redox ladder diagrams represents the electrochemical potential, E. The area of predominance is demarcated using the Nernst equation.
Consider the Fe3+/Fe2+ half-reaction, which has a standard-state potential of +0.771 V. At potentials more positive than +0.771 V, Fe3+ predominates, whereas Fe2+...
Consider the Fe3+/Fe2+ half-reaction, which has a standard-state potential of +0.771 V. At potentials more positive than +0.771 V, Fe3+ predominates, whereas Fe2+...
Electrogravimetric Analysis: Overview
Electrogravimetric analysis measures the weight of an analyte deposited electrolytically onto a suitable working electrode. This method involves applying a potential to a pre-weighed electrode submerged in a solution, which results in the desired substance being deposited through reduction at the cathode or oxidation at the anode. The electrode's weight is recorded after deposition, and the difference in weight gives the analyte's weight in the solution.
To test the completeness of the...
To test the completeness of the...
Standard Electrode Potentials
On comparing the reactivity of silver and lead, it is observed that the two ionic species, Ag+ (aq) and Pb2+ (aq), show a difference in their redox reactivity towards copper: the silver ion undergoes spontaneous reduction, while the lead ion does not. This relative redox activity can be easily quantified in electrochemical cells by a property called cell potential. This property is commonly known as cell voltage in electrochemistry, and it is a measure of the energy which accompanies the charge...
Voltammetric Techniques: Cyclic Voltammetry
Cyclic voltammetry (CV) is an electrochemical technique used to investigate the redox properties of a chemical species. It involves measuring the current response of an electrochemical cell as a function of the applied potential. The setup for cyclic voltammetry typically consists of a working electrode, a reference electrode, and a counter electrode—all immersed in an electrolyte solution. The working electrode is where the redox reaction of interest occurs, while the reference electrode...
Interfacial Electrochemical Methods: Overview
Interfacial electrochemical methods focus on the phenomena occurring at the boundary between an electrode and a solution, as opposed to bulk methods that concentrate on the solution's overall properties. These interfacial methods are classified as either static or dynamic based on the presence of a nonzero current in the electrochemical cell and the consistency of analyte concentrations. Static methods, such as potentiometry, measure the cell's potential without any significant current passing...


