Electrode Reaction Mechanisms

Electrode Reactions Are Chemical Reactions That Occur At The Electrode-Electrolyte Interface In An Electrolytic Cell. They Occur As A Result Of The Application Of A Voltage (An Electrical Current) To Electrodes Immersed In A Solvent Filled With Electrically Charged Ions, Thus Creating An Electrochemical Gradient Between The Two Electrodes. The Electrode Reaction Mechanisms Are Governed By A Set Of Chemical And Electrochemical Processes. When A Voltage Is Applied Across The Two Electrodes The Electrons Are Drawn Towards The Positively Charged Electrode (Anode), Whereas The Negatively Charged Ions (Anions) Move Towards The Negatively Charged Electrode (Cathode). The Electrode Reaction Can Be Described As A Redox Process, Where The Electron Transfer From The Anode To The Cathode Is Accompanied By A Stoichiometric Exchange Of Cations. The Initial Electrode Reaction Is Followed By A Series Of Secondary Reactions, Which May Be Either Secondary Electron Transfer, Chemical Interactions, Or Forms Of Complex Electron Transfer. The Rate At Which The Electrode Reaction Takes Place Depends On The Thermodynamic Equilibrium Of The Reaction And The Kinetics (Mechanism) Of The Reaction. Kinetically, Electrode Reactions Are Typically Divided Into Two Categories: Diffusion Controlled Electrode Reactions And Butler-Volmer Electrode Reactions. Diffusion-Controlled Electrode Reactions Are Those In Which Rate Of The Reaction Is Limited By The Rate Of Mass Transport Of Solute Species. The Reaction Rate Is Proportional To The Concentration Of Solute Species, And Is Determined By The Kinetic Energy Of The Reactants. Butler-Volmer Electrode Reactions Are Those In Which The Rate Of The Reaction Is Limited By The Rate Of Electron Transfer Across The Electrode-Electrolyte Interface. In These Reactions, The Reaction Rate Is Determined By The Voltage Applied Between The Electrodes. In Conclusion, Electrode Reactions Involve A Set Of Electrochemical And Chemical Processes That Take Place When An Electrical Current Is Applied Across Two Electrodes Immersed In A Solvent Filled With Electrically Charged Ions. The Rate Of The Reaction Is Determined By The Thermodynamic Equilibrium Of The Reaction And The Kinetics Of The Reaction, Which May Be Either Diffusion-Controlled Or Butler-Volmer.