Potentials of electrochemical reactions and nature of singularities in electrode polarization dependences

摘要

The conditions of transition of the electrochemical polarization mode to a faradaic process are studied on the metal electrode within the framework of the microscopic approach when the value of polarization potential reaches the threshold value of the potential of the electrochemical reaction. It is suggested that the elementary act of electron transfer between the metal and redox electrolyte occurs at the interface under polarization bringing the local electron level of the reagent to the Fermi level of electrons of the metal. Discharge through the Helmholtz layer limited by electrons occurs due to resonance "lightening" of the potential barrier between the metal and localized redox state of the reagent. Estimates are obtained for the values of threshold potential and exchange current of the faradaic process. A method is suggested for consideration of the elementary act of the electrochemical reaction on the basis of the Hamiltonian describing the microscopic mechanism of Fermi edge singularities. Application of the known solutions allows the appearance of threshold singularities of polarization dependences in electrochemistry to be explained.