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Showing posts from July, 2024

Spectroelectrochemistry: Bridging Electrochemical Insights with Optical Spectroscopy

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Traditional electrochemical methods are crucial for observing reactions at electrodes but face several limitations: Capacitance currents: Each time the electrode is polarized, it acts like a small capacitor, creating extra current that can interfere with the measurement data. Lack of Specificity: Unless the electrode is specifically functionalized, reactions at the electrode-water interface are often not selective, leading to unwanted side reactions or adsorption processes, complicating the interpretation of results. Electrode Geometry:  Variations in electrode size and surface roughness impact the shape of the voltammogram, changing the mass transport profile and electrical capacitances. Identifying Unknown Species:   Electrochemical methods are not suitable to identify unknown species that may form as intermediate or product in redox reactions. To address these limitations, researchers often turn to spectroelectrochemistry (SEC),  a technique that integrates elec...

Understanding cyclic voltammetry: Electron Transfer Mechanism

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Cyclic voltammetry (CV) is a widely used electrochemical technique for analyzing the charge transfer of a redox-active specie during a linearly cycled potential sweep. It provides valuable information about interfacial processes, redox thermodynamics, diffusion coefficients, electrode surface properties, and charge-transfer kinetics. However, despite its popularity, CV is often misunderstood due to the simultaneous occurrence of multiple processes, complicating the interpretation of voltammograms. Let's consider the following redox reaction: Fe2+kfkbFe3+ The rate of this reaction can be described phenomenologically as: r=kf[Fe2+]kb[Fe3+] In the classical chemical kinetics, the kinetic constant depends exponentially with temperature according to the Arrhenius equation: k=Aexp(EaRT) This equation tells us that the...