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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...
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Exploring Cyclic Voltammetry: Unraveling the Dynamics of Chemical Reactions Coupled with Electron Transfer

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In many cases, electrochecial systems are more complex than a simple interfacial electron transfer and may involve coupled chemical reactions. The presence of homogeneous chemical reactions in conjuction with the electrode process can significantly impact the electrochemical response of the system. In this blog, we will explore the scenario where a homogeneous first-order reaction is followed by an interfacial electron transfer, as described by the following sequence reactions: A⇌kfkbB+e− B+H+→k1BH Here k 1   is the homogeneous rate constant, and the species BH is considered electroinactive within the potential region under study. Additionally, we assume that the proton concentration is much higher than that of species B , allowing the homogeneous reaction to be approximated as a first-order reaction. Examples of this type of mechanism ...
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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...
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